xref: /external/mdnsresponder/mDNSCore/mDNS.c

/* -*- Mode: C; tab-width: 4 -*-
 *
 * Copyright (c) 2002-2006 Apple Computer, Inc. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * This code is completely 100% portable C. It does not depend on any external header files
 * from outside the mDNS project -- all the types it expects to find are defined right here.
 *
 * The previous point is very important: This file does not depend on any external
 * header files. It should compile on *any* platform that has a C compiler, without
 * making *any* assumptions about availability of so-called "standard" C functions,
 * routines, or types (which may or may not be present on any given platform).

 * Formatting notes:
 * This code follows the "Whitesmiths style" C indentation rules. Plenty of discussion
 * on C indentation can be found on the web, such as <http://www.kafejo.com/komp/1tbs.htm>,
 * but for the sake of brevity here I will say just this: Curly braces are not syntactially
 * part of an "if" statement; they are the beginning and ending markers of a compound statement;
 * therefore common sense dictates that if they are part of a compound statement then they
 * should be indented to the same level as everything else in that compound statement.
 * Indenting curly braces at the same level as the "if" implies that curly braces are
 * part of the "if", which is false. (This is as misleading as people who write "char* x,y;"
 * thinking that variables x and y are both of type "char*" -- and anyone who doesn't
 * understand why variable y is not of type "char*" just proves the point that poor code
 * layout leads people to unfortunate misunderstandings about how the C language really works.)
 */

#include "DNSCommon.h"                  // Defines general DNS untility routines
#include "uDNS.h"						// Defines entry points into unicast-specific routines

// Disable certain benign warnings with Microsoft compilers
#if(defined(_MSC_VER))
	// Disable "conditional expression is constant" warning for debug macros.
	// Otherwise, this generates warnings for the perfectly natural construct "while(1)"
	// If someone knows a variant way of writing "while(1)" that doesn't generate warning messages, please let us know
	#pragma warning(disable:4127)

	// Disable "assignment within conditional expression".
	// Other compilers understand the convention that if you place the assignment expression within an extra pair
	// of parentheses, this signals to the compiler that you really intended an assignment and no warning is necessary.
	// The Microsoft compiler doesn't understand this convention, so in the absense of any other way to signal
	// to the compiler that the assignment is intentional, we have to just turn this warning off completely.
	#pragma warning(disable:4706)
#endif

#if APPLE_OSX_mDNSResponder

#include <WebFilterDNS/WebFilterDNS.h>

#if ! NO_WCF
WCFConnection *WCFConnectionNew(void) __attribute__((weak_import));
void WCFConnectionDealloc(WCFConnection* c) __attribute__((weak_import));

// Do we really need to define a macro for "if"?
#define CHECK_WCF_FUNCTION(X) if (X)
#endif // ! NO_WCF

#else

#define NO_WCF 1
#endif // APPLE_OSX_mDNSResponder

// Forward declarations
mDNSlocal void BeginSleepProcessing(mDNS *const m);
mDNSlocal void RetrySPSRegistrations(mDNS *const m);
mDNSlocal void SendWakeup(mDNS *const m, mDNSInterfaceID InterfaceID, mDNSEthAddr *EthAddr, mDNSOpaque48 *password);
mDNSlocal mDNSBool CacheRecordRmvEventsForQuestion(mDNS *const m, DNSQuestion *q);
mDNSlocal mDNSBool LocalRecordRmvEventsForQuestion(mDNS *const m, DNSQuestion *q);
mDNSlocal void mDNS_PurgeBeforeResolve(mDNS *const m, DNSQuestion *q);

// ***************************************************************************
#if COMPILER_LIKES_PRAGMA_MARK
#pragma mark - Program Constants
#endif

#define NO_HINFO 1


// Any records bigger than this are considered 'large' records
#define SmallRecordLimit 1024

#define kMaxUpdateCredits 10
#define kUpdateCreditRefreshInterval (mDNSPlatformOneSecond * 6)

mDNSexport const char *const mDNS_DomainTypeNames[] =
	{
	 "b._dns-sd._udp.",		// Browse
	"db._dns-sd._udp.",		// Default Browse
	"lb._dns-sd._udp.",		// Automatic Browse
	 "r._dns-sd._udp.",		// Registration
	"dr._dns-sd._udp."		// Default Registration
	};

#ifdef UNICAST_DISABLED
#define uDNS_IsActiveQuery(q, u) mDNSfalse
#endif

// ***************************************************************************
#if COMPILER_LIKES_PRAGMA_MARK
#pragma mark -
#pragma mark - General Utility Functions
#endif

// If there is a authoritative LocalOnly record that answers questions of type A, AAAA and CNAME
// this returns true. Main use is to handle /etc/hosts records.
#define LORecordAnswersAddressType(rr) ((rr)->ARType == AuthRecordLocalOnly && \
									(rr)->resrec.RecordType & kDNSRecordTypeUniqueMask && \
									((rr)->resrec.rrtype == kDNSType_A || (rr)->resrec.rrtype == kDNSType_AAAA || \
									(rr)->resrec.rrtype == kDNSType_CNAME))

#define FollowCNAME(q, rr, AddRecord)	(AddRecord && (q)->qtype != kDNSType_CNAME && \
										(rr)->RecordType != kDNSRecordTypePacketNegative && \
										(rr)->rrtype == kDNSType_CNAME)

mDNSlocal void SetNextQueryStopTime(mDNS *const m, const DNSQuestion *const q)
	{
	if (m->mDNS_busy != m->mDNS_reentrancy+1)
		LogMsg("SetNextQueryTime: Lock not held! mDNS_busy (%ld) mDNS_reentrancy (%ld)", m->mDNS_busy, m->mDNS_reentrancy);

#if ForceAlerts
	if (m->mDNS_busy != m->mDNS_reentrancy+1) *(long*)0 = 0;
#endif

	if (m->NextScheduledStopTime - q->StopTime > 0)
		m->NextScheduledStopTime = q->StopTime;
	}

mDNSexport void SetNextQueryTime(mDNS *const m, const DNSQuestion *const q)
	{
	if (m->mDNS_busy != m->mDNS_reentrancy+1)
		LogMsg("SetNextQueryTime: Lock not held! mDNS_busy (%ld) mDNS_reentrancy (%ld)", m->mDNS_busy, m->mDNS_reentrancy);

#if ForceAlerts
	if (m->mDNS_busy != m->mDNS_reentrancy+1) *(long*)0 = 0;
#endif

	if (ActiveQuestion(q))
		{
		// Depending on whether this is a multicast or unicast question we want to set either:
		// m->NextScheduledQuery = NextQSendTime(q) or
		// m->NextuDNSEvent      = NextQSendTime(q)
		mDNSs32 *const timer = mDNSOpaque16IsZero(q->TargetQID) ? &m->NextScheduledQuery : &m->NextuDNSEvent;
		if (*timer - NextQSendTime(q) > 0)
			*timer = NextQSendTime(q);
		}
	}

mDNSlocal void ReleaseAuthEntity(AuthHash *r, AuthEntity *e)
	{
#if APPLE_OSX_mDNSResponder && MACOSX_MDNS_MALLOC_DEBUGGING >= 1
	unsigned int i;
	for (i=0; i<sizeof(*e); i++) ((char*)e)[i] = 0xFF;
#endif
	e->next = r->rrauth_free;
	r->rrauth_free = e;
	r->rrauth_totalused--;
	}

mDNSlocal void ReleaseAuthGroup(AuthHash *r, AuthGroup **cp)
	{
	AuthEntity *e = (AuthEntity *)(*cp);
	LogMsg("ReleaseAuthGroup:  Releasing AuthGroup %##s", (*cp)->name->c);
	if ((*cp)->rrauth_tail != &(*cp)->members)
		LogMsg("ERROR: (*cp)->members == mDNSNULL but (*cp)->rrauth_tail != &(*cp)->members)");
	if ((*cp)->name != (domainname*)((*cp)->namestorage)) mDNSPlatformMemFree((*cp)->name);
	(*cp)->name = mDNSNULL;
	*cp = (*cp)->next;			// Cut record from list
	ReleaseAuthEntity(r, e);
	}

mDNSlocal AuthEntity *GetAuthEntity(AuthHash *r, const AuthGroup *const PreserveAG)
	{
	AuthEntity *e = mDNSNULL;

	if (r->rrauth_lock) { LogMsg("GetFreeCacheRR ERROR! Cache already locked!"); return(mDNSNULL); }
	r->rrauth_lock = 1;

	if (!r->rrauth_free)
		{
		// We allocate just one AuthEntity at a time because we need to be able
		// free them all individually which normally happens when we parse /etc/hosts into
		// AuthHash where we add the "new" entries and discard (free) the already added
		// entries. If we allocate as chunks, we can't free them individually.
		AuthEntity *storage = mDNSPlatformMemAllocate(sizeof(AuthEntity));
		storage->next = mDNSNULL;
		r->rrauth_free = storage;
		}

	// If we still have no free records, recycle all the records we can.
	// Enumerating the entire auth is moderately expensive, so when we do it, we reclaim all the records we can in one pass.
	if (!r->rrauth_free)
		{
		mDNSu32 oldtotalused = r->rrauth_totalused;
		mDNSu32 slot;
		for (slot = 0; slot < AUTH_HASH_SLOTS; slot++)
			{
			AuthGroup **cp = &r->rrauth_hash[slot];
			while (*cp)
				{
				if ((*cp)->members || (*cp)==PreserveAG) cp=&(*cp)->next;
				else ReleaseAuthGroup(r, cp);
				}
			}
		LogInfo("GetAuthEntity: Recycled %d records to reduce auth cache from %d to %d",
			oldtotalused - r->rrauth_totalused, oldtotalused, r->rrauth_totalused);
		}

	if (r->rrauth_free)	// If there are records in the free list, take one
		{
		e = r->rrauth_free;
		r->rrauth_free = e->next;
		if (++r->rrauth_totalused >= r->rrauth_report)
			{
			LogInfo("RR Auth now using %ld objects", r->rrauth_totalused);
			if      (r->rrauth_report <  100) r->rrauth_report += 10;
			else if (r->rrauth_report < 1000) r->rrauth_report += 100;
			else                               r->rrauth_report += 1000;
			}
		mDNSPlatformMemZero(e, sizeof(*e));
		}

	r->rrauth_lock = 0;

	return(e);
	}

mDNSexport AuthGroup *AuthGroupForName(AuthHash *r, const mDNSu32 slot, const mDNSu32 namehash, const domainname *const name)
	{
	AuthGroup *ag;
	for (ag = r->rrauth_hash[slot]; ag; ag=ag->next)
		if (ag->namehash == namehash && SameDomainName(ag->name, name))
			break;
	return(ag);
	}

mDNSexport AuthGroup *AuthGroupForRecord(AuthHash *r, const mDNSu32 slot, const ResourceRecord *const rr)
	{
	return(AuthGroupForName(r, slot, rr->namehash, rr->name));
	}

mDNSlocal AuthGroup *GetAuthGroup(AuthHash *r, const mDNSu32 slot, const ResourceRecord *const rr)
	{
	mDNSu16 namelen = DomainNameLength(rr->name);
	AuthGroup *ag = (AuthGroup*)GetAuthEntity(r, mDNSNULL);
	if (!ag) { LogMsg("GetAuthGroup: Failed to allocate memory for %##s", rr->name->c); return(mDNSNULL); }
	ag->next         = r->rrauth_hash[slot];
	ag->namehash     = rr->namehash;
	ag->members      = mDNSNULL;
	ag->rrauth_tail  = &ag->members;
	ag->name         = (domainname*)ag->namestorage;
	ag->NewLocalOnlyRecords = mDNSNULL;
	if (namelen > InlineCacheGroupNameSize) ag->name = mDNSPlatformMemAllocate(namelen);
	if (!ag->name)
		{
		LogMsg("GetAuthGroup: Failed to allocate name storage for %##s", rr->name->c);
		ReleaseAuthEntity(r, (AuthEntity*)ag);
		return(mDNSNULL);
		}
	AssignDomainName(ag->name, rr->name);

	if (AuthGroupForRecord(r, slot, rr)) LogMsg("GetAuthGroup: Already have AuthGroup for %##s", rr->name->c);
	r->rrauth_hash[slot] = ag;
	if (AuthGroupForRecord(r, slot, rr) != ag) LogMsg("GetAuthGroup: Not finding AuthGroup for %##s", rr->name->c);

	return(ag);
	}

// Returns the AuthGroup in which the AuthRecord was inserted
mDNSexport AuthGroup *InsertAuthRecord(mDNS *const m, AuthHash *r, AuthRecord *rr)
	{
	AuthGroup *ag;
	const mDNSu32 slot = AuthHashSlot(rr->resrec.name);
	ag = AuthGroupForRecord(r, slot, &rr->resrec);
	if (!ag) ag = GetAuthGroup(r, slot, &rr->resrec);	// If we don't have a AuthGroup for this name, make one now
	if (ag)
		{
		LogInfo("InsertAuthRecord: inserting auth record %s from table", ARDisplayString(m, rr));
		*(ag->rrauth_tail) = rr;				// Append this record to tail of cache slot list
		ag->rrauth_tail = &(rr->next);			// Advance tail pointer
		}
	return ag;
	}

mDNSexport AuthGroup *RemoveAuthRecord(mDNS *const m, AuthHash *r, AuthRecord *rr)
	{
	AuthGroup *a;
	AuthGroup **ag = &a;
	AuthRecord **rp;
	const mDNSu32 slot = AuthHashSlot(rr->resrec.name);

	a = AuthGroupForRecord(r, slot, &rr->resrec);
	if (!a) { LogMsg("RemoveAuthRecord: ERROR!! AuthGroup not found for %s", ARDisplayString(m, rr)); return mDNSNULL; }
	rp = &(*ag)->members;
	while (*rp)
		{
		if (*rp != rr)
			rp=&(*rp)->next;
		else
			{
			// We don't break here, so that we can set the tail below without tracking "prev" pointers

			LogInfo("RemoveAuthRecord: removing auth record %s from table", ARDisplayString(m, rr));
			*rp = (*rp)->next;			// Cut record from list
			}
		}
	// TBD: If there are no more members, release authgroup ?
	(*ag)->rrauth_tail = rp;
	return a;
	}

mDNSexport CacheGroup *CacheGroupForName(const mDNS *const m, const mDNSu32 slot, const mDNSu32 namehash, const domainname *const name)
	{
	CacheGroup *cg;
	for (cg = m->rrcache_hash[slot]; cg; cg=cg->next)
		if (cg->namehash == namehash && SameDomainName(cg->name, name))
			break;
	return(cg);
	}

mDNSlocal CacheGroup *CacheGroupForRecord(const mDNS *const m, const mDNSu32 slot, const ResourceRecord *const rr)
	{
	return(CacheGroupForName(m, slot, rr->namehash, rr->name));
	}

mDNSexport mDNSBool mDNS_AddressIsLocalSubnet(mDNS *const m, const mDNSInterfaceID InterfaceID, const mDNSAddr *addr)
	{
	NetworkInterfaceInfo *intf;

	if (addr->type == mDNSAddrType_IPv4)
		{
		// Normally we resist touching the NotAnInteger fields, but here we're doing tricky bitwise masking so we make an exception
		if (mDNSv4AddressIsLinkLocal(&addr->ip.v4)) return(mDNStrue);
		for (intf = m->HostInterfaces; intf; intf = intf->next)
			if (intf->ip.type == addr->type && intf->InterfaceID == InterfaceID && intf->McastTxRx)
				if (((intf->ip.ip.v4.NotAnInteger ^ addr->ip.v4.NotAnInteger) & intf->mask.ip.v4.NotAnInteger) == 0)
					return(mDNStrue);
		}

	if (addr->type == mDNSAddrType_IPv6)
		{
		if (mDNSv6AddressIsLinkLocal(&addr->ip.v6)) return(mDNStrue);
		for (intf = m->HostInterfaces; intf; intf = intf->next)
			if (intf->ip.type == addr->type && intf->InterfaceID == InterfaceID && intf->McastTxRx)
				if ((((intf->ip.ip.v6.l[0] ^ addr->ip.v6.l[0]) & intf->mask.ip.v6.l[0]) == 0) &&
					(((intf->ip.ip.v6.l[1] ^ addr->ip.v6.l[1]) & intf->mask.ip.v6.l[1]) == 0) &&
					(((intf->ip.ip.v6.l[2] ^ addr->ip.v6.l[2]) & intf->mask.ip.v6.l[2]) == 0) &&
					(((intf->ip.ip.v6.l[3] ^ addr->ip.v6.l[3]) & intf->mask.ip.v6.l[3]) == 0))
						return(mDNStrue);
		}

	return(mDNSfalse);
	}

mDNSlocal NetworkInterfaceInfo *FirstInterfaceForID(mDNS *const m, const mDNSInterfaceID InterfaceID)
	{
	NetworkInterfaceInfo *intf = m->HostInterfaces;
	while (intf && intf->InterfaceID != InterfaceID) intf = intf->next;
	return(intf);
	}

mDNSexport char *InterfaceNameForID(mDNS *const m, const mDNSInterfaceID InterfaceID)
	{
	NetworkInterfaceInfo *intf = FirstInterfaceForID(m, InterfaceID);
	return(intf ? intf->ifname : mDNSNULL);
	}

// Caller should hold the lock
mDNSlocal void GenerateNegativeResponse(mDNS *const m)
	{
	DNSQuestion *q;
	if (!m->CurrentQuestion) { LogMsg("GenerateNegativeResponse: ERROR!! CurrentQuestion not set"); return; }
	q = m->CurrentQuestion;
	LogInfo("GenerateNegativeResponse: Generating negative response for question %##s (%s)", q->qname.c, DNSTypeName(q->qtype));

	MakeNegativeCacheRecord(m, &m->rec.r, &q->qname, q->qnamehash, q->qtype, q->qclass, 60, mDNSInterface_Any, mDNSNULL);
	AnswerCurrentQuestionWithResourceRecord(m, &m->rec.r, QC_addnocache);
	if (m->CurrentQuestion == q) { q->ThisQInterval = 0; }				// Deactivate this question
	// Don't touch the question after this
	m->rec.r.resrec.RecordType = 0;		// Clear RecordType to show we're not still using it
	}

mDNSlocal void AnswerQuestionByFollowingCNAME(mDNS *const m, DNSQuestion *q, ResourceRecord *rr)
	{
	const mDNSBool selfref = SameDomainName(&q->qname, &rr->rdata->u.name);
	if (q->CNAMEReferrals >= 10 || selfref)
		LogMsg("AnswerQuestionByFollowingCNAME: %p %##s (%s) NOT following CNAME referral %d%s for %s",
			q, q->qname.c, DNSTypeName(q->qtype), q->CNAMEReferrals, selfref ? " (Self-Referential)" : "", RRDisplayString(m, rr));
	else
		{
		const mDNSu32 c = q->CNAMEReferrals + 1;		// Stash a copy of the new q->CNAMEReferrals value

		// The SameDomainName check above is to ignore bogus CNAME records that point right back at
		// themselves. Without that check we can get into a case where we have two duplicate questions,
		// A and B, and when we stop question A, UpdateQuestionDuplicates copies the value of CNAMEReferrals
		// from A to B, and then A is re-appended to the end of the list as a duplicate of B (because
		// the target name is still the same), and then when we stop question B, UpdateQuestionDuplicates
		// copies the B's value of CNAMEReferrals back to A, and we end up not incrementing CNAMEReferrals
		// for either of them. This is not a problem for CNAME loops of two or more records because in
		// those cases the newly re-appended question A has a different target name and therefore cannot be
		// a duplicate of any other question ('B') which was itself a duplicate of the previous question A.

		// Right now we just stop and re-use the existing query. If we really wanted to be 100% perfect,
		// and track CNAMEs coming and going, we should really create a subordinate query here,
		// which we would subsequently cancel and retract if the CNAME referral record were removed.
		// In reality this is such a corner case we'll ignore it until someone actually needs it.

		LogInfo("AnswerQuestionByFollowingCNAME: %p %##s (%s) following CNAME referral %d for %s",
			q, q->qname.c, DNSTypeName(q->qtype), q->CNAMEReferrals, RRDisplayString(m, rr));

		mDNS_StopQuery_internal(m, q);								// Stop old query
		AssignDomainName(&q->qname, &rr->rdata->u.name);			// Update qname
		q->qnamehash = DomainNameHashValue(&q->qname);				// and namehash
		// If a unicast query results in a CNAME that points to a .local, we need to re-try
		// this as unicast. Setting the mDNSInterface_Unicast tells mDNS_StartQuery_internal
		// to try this as unicast query even though it is a .local name
		if (!mDNSOpaque16IsZero(q->TargetQID) && IsLocalDomain(&q->qname))
			{
			LogInfo("AnswerQuestionByFollowingCNAME: Resolving a .local CNAME %p %##s (%s) Record %s",
				q, q->qname.c, DNSTypeName(q->qtype), RRDisplayString(m, rr));
			q->InterfaceID = mDNSInterface_Unicast;
			}
		mDNS_StartQuery_internal(m, q);								// start new query
		// Record how many times we've done this. We need to do this *after* mDNS_StartQuery_internal,
		// because mDNS_StartQuery_internal re-initializes CNAMEReferrals to zero
		q->CNAMEReferrals = c;
		}
	}

// For a single given DNSQuestion pointed to by CurrentQuestion, deliver an add/remove result for the single given AuthRecord
// Note: All the callers should use the m->CurrentQuestion to see if the question is still valid or not
mDNSlocal void AnswerLocalQuestionWithLocalAuthRecord(mDNS *const m, AuthRecord *rr, QC_result AddRecord)
	{
	DNSQuestion *q = m->CurrentQuestion;
	mDNSBool followcname;

	if (!q)
		{
		LogMsg("AnswerLocalQuestionWithLocalAuthRecord: ERROR!! CurrentQuestion NULL while answering with %s", ARDisplayString(m, rr));
		return;
		}

	followcname = FollowCNAME(q, &rr->resrec, AddRecord);

	// We should not be delivering results for record types Unregistered, Deregistering, and (unverified) Unique
	if (!(rr->resrec.RecordType & kDNSRecordTypeActiveMask))
		{
		LogMsg("AnswerLocalQuestionWithLocalAuthRecord: *NOT* delivering %s event for local record type %X %s",
			AddRecord ? "Add" : "Rmv", rr->resrec.RecordType, ARDisplayString(m, rr));
		return;
		}

	// Indicate that we've given at least one positive answer for this record, so we should be prepared to send a goodbye for it
	if (AddRecord) rr->AnsweredLocalQ = mDNStrue;
	mDNS_DropLockBeforeCallback();		// Allow client to legally make mDNS API calls from the callback
	if (q->QuestionCallback && !q->NoAnswer)
		{
		q->CurrentAnswers += AddRecord ? 1 : -1;
 		if (LORecordAnswersAddressType(rr))
			{
			if (!followcname || q->ReturnIntermed)
				{
				// Don't send this packet on the wire as we answered from /etc/hosts
				q->ThisQInterval = 0;
				q->LOAddressAnswers += AddRecord ? 1 : -1;
				q->QuestionCallback(m, q, &rr->resrec, AddRecord);
				}
			mDNS_ReclaimLockAfterCallback();	// Decrement mDNS_reentrancy to block mDNS API calls again
			// The callback above could have caused the question to stop. Detect that
			// using m->CurrentQuestion
			if (followcname && m->CurrentQuestion == q)
				AnswerQuestionByFollowingCNAME(m, q, &rr->resrec);
			return;
			}
		else
			q->QuestionCallback(m, q, &rr->resrec, AddRecord);
		}
	mDNS_ReclaimLockAfterCallback();	// Decrement mDNS_reentrancy to block mDNS API calls again
	}

mDNSlocal void AnswerInterfaceAnyQuestionsWithLocalAuthRecord(mDNS *const m, AuthRecord *rr, QC_result AddRecord)
 	{
 	if (m->CurrentQuestion)
 		LogMsg("AnswerInterfaceAnyQuestionsWithLocalAuthRecord: ERROR m->CurrentQuestion already set: %##s (%s)",
 			m->CurrentQuestion->qname.c, DNSTypeName(m->CurrentQuestion->qtype));
 	m->CurrentQuestion = m->Questions;
 	while (m->CurrentQuestion && m->CurrentQuestion != m->NewQuestions)
 		{
		mDNSBool answered;
 		DNSQuestion *q = m->CurrentQuestion;
		if (RRAny(rr))
			answered = ResourceRecordAnswersQuestion(&rr->resrec, q);
		else
			answered = LocalOnlyRecordAnswersQuestion(rr, q);
 		if (answered)
 			AnswerLocalQuestionWithLocalAuthRecord(m, rr, AddRecord);		// MUST NOT dereference q again
		if (m->CurrentQuestion == q)	// If m->CurrentQuestion was not auto-advanced, do it ourselves now
			m->CurrentQuestion = q->next;
 		}
 	m->CurrentQuestion = mDNSNULL;
 	}

// When a new local AuthRecord is created or deleted, AnswerAllLocalQuestionsWithLocalAuthRecord()
// delivers the appropriate add/remove events to listening questions:
// 1. It runs though all our LocalOnlyQuestions delivering answers as appropriate,
//    stopping if it reaches a NewLocalOnlyQuestion -- brand-new questions are handled by AnswerNewLocalOnlyQuestion().
// 2. If the AuthRecord is marked mDNSInterface_LocalOnly or mDNSInterface_P2P, then it also runs though
//    our main question list, delivering answers to mDNSInterface_Any questions as appropriate,
//    stopping if it reaches a NewQuestion -- brand-new questions are handled by AnswerNewQuestion().
//
// AnswerAllLocalQuestionsWithLocalAuthRecord is used by the m->NewLocalRecords loop in mDNS_Execute(),
// and by mDNS_Deregister_internal()

mDNSlocal void AnswerAllLocalQuestionsWithLocalAuthRecord(mDNS *const m, AuthRecord *rr, QC_result AddRecord)
	{
	if (m->CurrentQuestion)
		LogMsg("AnswerAllLocalQuestionsWithLocalAuthRecord ERROR m->CurrentQuestion already set: %##s (%s)",
			m->CurrentQuestion->qname.c, DNSTypeName(m->CurrentQuestion->qtype));

	m->CurrentQuestion = m->LocalOnlyQuestions;
	while (m->CurrentQuestion && m->CurrentQuestion != m->NewLocalOnlyQuestions)
		{
		mDNSBool answered;
		DNSQuestion *q = m->CurrentQuestion;
		// We are called with both LocalOnly/P2P record or a regular AuthRecord
		if (RRAny(rr))
			answered = ResourceRecordAnswersQuestion(&rr->resrec, q);
		else
			answered = LocalOnlyRecordAnswersQuestion(rr, q);
		if (answered)
			AnswerLocalQuestionWithLocalAuthRecord(m, rr, AddRecord);			// MUST NOT dereference q again
		if (m->CurrentQuestion == q)	// If m->CurrentQuestion was not auto-advanced, do it ourselves now
			m->CurrentQuestion = q->next;
		}

	m->CurrentQuestion = mDNSNULL;

	// If this AuthRecord is marked LocalOnly or P2P, then we want to deliver it to all local 'mDNSInterface_Any' questions
	if (rr->ARType == AuthRecordLocalOnly || rr->ARType == AuthRecordP2P)
		AnswerInterfaceAnyQuestionsWithLocalAuthRecord(m, rr, AddRecord);

	}

// ***************************************************************************
#if COMPILER_LIKES_PRAGMA_MARK
#pragma mark -
#pragma mark - Resource Record Utility Functions
#endif

#define RRTypeIsAddressType(T) ((T) == kDNSType_A || (T) == kDNSType_AAAA)

#define ResourceRecordIsValidAnswer(RR) ( ((RR)->             resrec.RecordType & kDNSRecordTypeActiveMask)  && \
		((RR)->Additional1 == mDNSNULL || ((RR)->Additional1->resrec.RecordType & kDNSRecordTypeActiveMask)) && \
		((RR)->Additional2 == mDNSNULL || ((RR)->Additional2->resrec.RecordType & kDNSRecordTypeActiveMask)) && \
		((RR)->DependentOn == mDNSNULL || ((RR)->DependentOn->resrec.RecordType & kDNSRecordTypeActiveMask))  )

#define ResourceRecordIsValidInterfaceAnswer(RR, INTID) \
	(ResourceRecordIsValidAnswer(RR) && \
	((RR)->resrec.InterfaceID == mDNSInterface_Any || (RR)->resrec.InterfaceID == (INTID)))

#define DefaultProbeCountForTypeUnique ((mDNSu8)3)
#define DefaultProbeCountForRecordType(X)      ((X) == kDNSRecordTypeUnique ? DefaultProbeCountForTypeUnique : (mDNSu8)0)

#define InitialAnnounceCount ((mDNSu8)8)

// For goodbye packets we set the count to 3, and for wakeups we set it to 18
// (which will be up to 15 wakeup attempts over the course of 30 seconds,
// and then if the machine fails to wake, 3 goodbye packets).
#define GoodbyeCount ((mDNSu8)3)
#define WakeupCount ((mDNSu8)18)

// Number of wakeups we send if WakeOnResolve is set in the question
#define InitialWakeOnResolveCount ((mDNSu8)3)

// Note that the announce intervals use exponential backoff, doubling each time. The probe intervals do not.
// This means that because the announce interval is doubled after sending the first packet, the first
// observed on-the-wire inter-packet interval between announcements is actually one second.
// The half-second value here may be thought of as a conceptual (non-existent) half-second delay *before* the first packet is sent.
#define DefaultProbeIntervalForTypeUnique (mDNSPlatformOneSecond/4)
#define DefaultAnnounceIntervalForTypeShared (mDNSPlatformOneSecond/2)
#define DefaultAnnounceIntervalForTypeUnique (mDNSPlatformOneSecond/2)

#define DefaultAPIntervalForRecordType(X)  ((X) & kDNSRecordTypeActiveSharedMask ? DefaultAnnounceIntervalForTypeShared : \
											(X) & kDNSRecordTypeUnique           ? DefaultProbeIntervalForTypeUnique    : \
											(X) & kDNSRecordTypeActiveUniqueMask ? DefaultAnnounceIntervalForTypeUnique : 0)

#define TimeToAnnounceThisRecord(RR,time) ((RR)->AnnounceCount && (time) - ((RR)->LastAPTime + (RR)->ThisAPInterval) >= 0)
#define TimeToSendThisRecord(RR,time) ((TimeToAnnounceThisRecord(RR,time) || (RR)->ImmedAnswer) && ResourceRecordIsValidAnswer(RR))
#define TicksTTL(RR) ((mDNSs32)(RR)->resrec.rroriginalttl * mDNSPlatformOneSecond)
#define RRExpireTime(RR) ((RR)->TimeRcvd + TicksTTL(RR))

#define MaxUnansweredQueries 4

// SameResourceRecordSignature returns true if two resources records have the same name, type, and class, and may be sent
// (or were received) on the same interface (i.e. if *both* records specify an interface, then it has to match).
// TTL and rdata may differ.
// This is used for cache flush management:
// When sending a unique record, all other records matching "SameResourceRecordSignature" must also be sent
// When receiving a unique record, all old cache records matching "SameResourceRecordSignature" are flushed

// SameResourceRecordNameClassInterface is functionally the same as SameResourceRecordSignature, except rrtype does not have to match

#define SameResourceRecordSignature(A,B) (A)->resrec.rrtype == (B)->resrec.rrtype && SameResourceRecordNameClassInterface((A),(B))

mDNSlocal mDNSBool SameResourceRecordNameClassInterface(const AuthRecord *const r1, const AuthRecord *const r2)
	{
	if (!r1) { LogMsg("SameResourceRecordSignature ERROR: r1 is NULL"); return(mDNSfalse); }
	if (!r2) { LogMsg("SameResourceRecordSignature ERROR: r2 is NULL"); return(mDNSfalse); }
	if (r1->resrec.InterfaceID &&
		r2->resrec.InterfaceID &&
		r1->resrec.InterfaceID != r2->resrec.InterfaceID) return(mDNSfalse);
	return(mDNSBool)(
		r1->resrec.rrclass  == r2->resrec.rrclass &&
		r1->resrec.namehash == r2->resrec.namehash &&
		SameDomainName(r1->resrec.name, r2->resrec.name));
	}

// PacketRRMatchesSignature behaves as SameResourceRecordSignature, except that types may differ if our
// authoratative record is unique (as opposed to shared). For unique records, we are supposed to have
// complete ownership of *all* types for this name, so *any* record type with the same name is a conflict.
// In addition, when probing we send our questions with the wildcard type kDNSQType_ANY,
// so a response of any type should match, even if it is not actually the type the client plans to use.

// For now, to make it easier to avoid false conflicts, we treat SPS Proxy records like shared records,
// and require the rrtypes to match for the rdata to be considered potentially conflicting
mDNSlocal mDNSBool PacketRRMatchesSignature(const CacheRecord *const pktrr, const AuthRecord *const authrr)
	{
	if (!pktrr)  { LogMsg("PacketRRMatchesSignature ERROR: pktrr is NULL"); return(mDNSfalse); }
	if (!authrr) { LogMsg("PacketRRMatchesSignature ERROR: authrr is NULL"); return(mDNSfalse); }
	if (pktrr->resrec.InterfaceID &&
		authrr->resrec.InterfaceID &&
		pktrr->resrec.InterfaceID != authrr->resrec.InterfaceID) return(mDNSfalse);
	if (!(authrr->resrec.RecordType & kDNSRecordTypeUniqueMask) || authrr->WakeUp.HMAC.l[0])
		if (pktrr->resrec.rrtype != authrr->resrec.rrtype) return(mDNSfalse);
	return(mDNSBool)(
		pktrr->resrec.rrclass == authrr->resrec.rrclass &&
		pktrr->resrec.namehash == authrr->resrec.namehash &&
		SameDomainName(pktrr->resrec.name, authrr->resrec.name));
	}

// CacheRecord *ka is the CacheRecord from the known answer list in the query.
// This is the information that the requester believes to be correct.
// AuthRecord *rr is the answer we are proposing to give, if not suppressed.
// This is the information that we believe to be correct.
// We've already determined that we plan to give this answer on this interface
// (either the record is non-specific, or it is specific to this interface)
// so now we just need to check the name, type, class, rdata and TTL.
mDNSlocal mDNSBool ShouldSuppressKnownAnswer(const CacheRecord *const ka, const AuthRecord *const rr)
	{
	// If RR signature is different, or data is different, then don't suppress our answer
	if (!IdenticalResourceRecord(&ka->resrec, &rr->resrec)) return(mDNSfalse);

	// If the requester's indicated TTL is less than half the real TTL,
	// we need to give our answer before the requester's copy expires.
	// If the requester's indicated TTL is at least half the real TTL,
	// then we can suppress our answer this time.
	// If the requester's indicated TTL is greater than the TTL we believe,
	// then that's okay, and we don't need to do anything about it.
	// (If two responders on the network are offering the same information,
	// that's okay, and if they are offering the information with different TTLs,
	// the one offering the lower TTL should defer to the one offering the higher TTL.)
	return(mDNSBool)(ka->resrec.rroriginalttl >= rr->resrec.rroriginalttl / 2);
	}

mDNSlocal void SetNextAnnounceProbeTime(mDNS *const m, const AuthRecord *const rr)
	{
	if (rr->resrec.RecordType == kDNSRecordTypeUnique)
		{
		if ((rr->LastAPTime + rr->ThisAPInterval) - m->timenow > mDNSPlatformOneSecond * 10)
			{
			LogMsg("SetNextAnnounceProbeTime: ProbeCount %d Next in %d %s", rr->ProbeCount, (rr->LastAPTime + rr->ThisAPInterval) - m->timenow, ARDisplayString(m, rr));
			LogMsg("SetNextAnnounceProbeTime: m->SuppressProbes %d m->timenow %d diff %d", m->SuppressProbes, m->timenow, m->SuppressProbes - m->timenow);
			}
		if (m->NextScheduledProbe - (rr->LastAPTime + rr->ThisAPInterval) >= 0)
			m->NextScheduledProbe = (rr->LastAPTime + rr->ThisAPInterval);
		// Some defensive code:
		// If (rr->LastAPTime + rr->ThisAPInterval) happens to be far in the past, we don't want to allow
		// NextScheduledProbe to be set excessively in the past, because that can cause bad things to happen.
		// See: <rdar://problem/7795434> mDNS: Sometimes advertising stops working and record interval is set to zero
		if (m->NextScheduledProbe - m->timenow < 0)
			m->NextScheduledProbe = m->timenow;
		}
	else if (rr->AnnounceCount && (ResourceRecordIsValidAnswer(rr) || rr->resrec.RecordType == kDNSRecordTypeDeregistering))
		{
		if (m->NextScheduledResponse - (rr->LastAPTime + rr->ThisAPInterval) >= 0)
			m->NextScheduledResponse = (rr->LastAPTime + rr->ThisAPInterval);
		}
	}

mDNSlocal void InitializeLastAPTime(mDNS *const m, AuthRecord *const rr)
	{
	// For reverse-mapping Sleep Proxy PTR records, probe interval is one second
	rr->ThisAPInterval = rr->AddressProxy.type ? mDNSPlatformOneSecond : DefaultAPIntervalForRecordType(rr->resrec.RecordType);

	// * If this is a record type that's going to probe, then we use the m->SuppressProbes time.
	// * Otherwise, if it's not going to probe, but m->SuppressProbes is set because we have other
	//   records that are going to probe, then we delay its first announcement so that it will
	//   go out synchronized with the first announcement for the other records that *are* probing.
	//   This is a minor performance tweak that helps keep groups of related records synchronized together.
	//   The addition of "interval / 2" is to make sure that, in the event that any of the probes are
	//   delayed by a few milliseconds, this announcement does not inadvertently go out *before* the probing is complete.
	//   When the probing is complete and those records begin to announce, these records will also be picked up and accelerated,
	//   because they will meet the criterion of being at least half-way to their scheduled announcement time.
	// * If it's not going to probe and m->SuppressProbes is not already set then we should announce immediately.

	if (rr->ProbeCount)
		{
		// If we have no probe suppression time set, or it is in the past, set it now
		if (m->SuppressProbes == 0 || m->SuppressProbes - m->timenow < 0)
			{
			// To allow us to aggregate probes when a group of services are registered together,
			// the first probe is delayed 1/4 second. This means the common-case behaviour is:
			// 1/4 second wait; probe
			// 1/4 second wait; probe
			// 1/4 second wait; probe
			// 1/4 second wait; announce (i.e. service is normally announced exactly one second after being registered)
			m->SuppressProbes = NonZeroTime(m->timenow + DefaultProbeIntervalForTypeUnique/2 + mDNSRandom(DefaultProbeIntervalForTypeUnique/2));

			// If we already have a *probe* scheduled to go out sooner, then use that time to get better aggregation
			if (m->SuppressProbes - m->NextScheduledProbe >= 0)
				m->SuppressProbes = NonZeroTime(m->NextScheduledProbe);
			if (m->SuppressProbes - m->timenow < 0)		// Make sure we don't set m->SuppressProbes excessively in the past
				m->SuppressProbes = m->timenow;

			// If we already have a *query* scheduled to go out sooner, then use that time to get better aggregation
			if (m->SuppressProbes - m->NextScheduledQuery >= 0)
				m->SuppressProbes = NonZeroTime(m->NextScheduledQuery);
			if (m->SuppressProbes - m->timenow < 0)		// Make sure we don't set m->SuppressProbes excessively in the past
				m->SuppressProbes = m->timenow;

			// except... don't expect to be able to send before the m->SuppressSending timer fires
			if (m->SuppressSending && m->SuppressProbes - m->SuppressSending < 0)
				m->SuppressProbes = NonZeroTime(m->SuppressSending);

			if (m->SuppressProbes - m->timenow > mDNSPlatformOneSecond * 8)
				{
				LogMsg("InitializeLastAPTime ERROR m->SuppressProbes %d m->NextScheduledProbe %d m->NextScheduledQuery %d m->SuppressSending %d %d",
					m->SuppressProbes     - m->timenow,
					m->NextScheduledProbe - m->timenow,
					m->NextScheduledQuery - m->timenow,
					m->SuppressSending,
					m->SuppressSending    - m->timenow);
				m->SuppressProbes = NonZeroTime(m->timenow + DefaultProbeIntervalForTypeUnique/2 + mDNSRandom(DefaultProbeIntervalForTypeUnique/2));
				}
			}
		rr->LastAPTime = m->SuppressProbes - rr->ThisAPInterval;
		}
	else if (m->SuppressProbes && m->SuppressProbes - m->timenow >= 0)
		rr->LastAPTime = m->SuppressProbes - rr->ThisAPInterval + DefaultProbeIntervalForTypeUnique * DefaultProbeCountForTypeUnique + rr->ThisAPInterval / 2;
	else
		rr->LastAPTime = m->timenow - rr->ThisAPInterval;

	// For reverse-mapping Sleep Proxy PTR records we don't want to start probing instantly -- we
	// wait one second to give the client a chance to go to sleep, and then start our ARP/NDP probing.
	// After three probes one second apart with no answer, we conclude the client is now sleeping
	// and we can begin broadcasting our announcements to take over ownership of that IP address.
	// If we don't wait for the client to go to sleep, then when the client sees our ARP Announcements there's a risk
	// (depending on the OS and networking stack it's using) that it might interpret it as a conflict and change its IP address.
	if (rr->AddressProxy.type) rr->LastAPTime = m->timenow;

	// Unsolicited Neighbor Advertisements (RFC 2461 Section 7.2.6) give us fast address cache updating,
	// but some older IPv6 clients get confused by them, so for now we don't send them. Without Unsolicited
	// Neighbor Advertisements we have to rely on Neighbor Unreachability Detection instead, which is slower.
	// Given this, we'll do our best to wake for existing IPv6 connections, but we don't want to encourage
	// new ones for sleeping clients, so we'll we send deletions for our SPS clients' AAAA records.
	if (m->KnownBugs & mDNS_KnownBug_LimitedIPv6)
		if (rr->WakeUp.HMAC.l[0] && rr->resrec.rrtype == kDNSType_AAAA)
			rr->LastAPTime = m->timenow - rr->ThisAPInterval + mDNSPlatformOneSecond * 10;

	// Set LastMCTime to now, to inhibit multicast responses
	// (no need to send additional multicast responses when we're announcing anyway)
	rr->LastMCTime      = m->timenow;
	rr->LastMCInterface = mDNSInterfaceMark;

	SetNextAnnounceProbeTime(m, rr);
	}

mDNSlocal const domainname *SetUnicastTargetToHostName(mDNS *const m, AuthRecord *rr)
	{
	const domainname *target;
	if (rr->AutoTarget)
		{
		// For autotunnel services pointing at our IPv6 ULA we don't need or want a NAT mapping, but for all other
		// advertised services referencing our uDNS hostname, we want NAT mappings automatically created as appropriate,
		// with the port number in our advertised SRV record automatically tracking the external mapped port.
		DomainAuthInfo *AuthInfo = GetAuthInfoForName_internal(m, rr->resrec.name);
		if (!AuthInfo || !AuthInfo->AutoTunnel) rr->AutoTarget = Target_AutoHostAndNATMAP;
		}

	target = GetServiceTarget(m, rr);
	if (!target || target->c[0] == 0)
		{
		// defer registration until we've got a target
		LogInfo("SetUnicastTargetToHostName No target for %s", ARDisplayString(m, rr));
		rr->state = regState_NoTarget;
		return mDNSNULL;
		}
	else
		{
		LogInfo("SetUnicastTargetToHostName target %##s for resource record %s", target->c, ARDisplayString(m,rr));
		return target;
		}
	}

// Right now this only applies to mDNS (.local) services where the target host is always m->MulticastHostname
// Eventually we should unify this with GetServiceTarget() in uDNS.c
mDNSlocal void SetTargetToHostName(mDNS *const m, AuthRecord *const rr)
	{
	domainname *const target = GetRRDomainNameTarget(&rr->resrec);
	const domainname *newname = &m->MulticastHostname;

	if (!target) LogInfo("SetTargetToHostName: Don't know how to set the target of rrtype %s", DNSTypeName(rr->resrec.rrtype));

	if (!(rr->ForceMCast || rr->ARType == AuthRecordLocalOnly || rr->ARType == AuthRecordP2P || IsLocalDomain(&rr->namestorage)))
		{
		const domainname *const n = SetUnicastTargetToHostName(m, rr);
		if (n) newname = n;
		else { target->c[0] = 0; SetNewRData(&rr->resrec, mDNSNULL, 0); return; }
		}

	if (target && SameDomainName(target, newname))
		debugf("SetTargetToHostName: Target of %##s is already %##s", rr->resrec.name->c, target->c);

	if (target && !SameDomainName(target, newname))
		{
		AssignDomainName(target, newname);
		SetNewRData(&rr->resrec, mDNSNULL, 0);		// Update rdlength, rdestimate, rdatahash

		// If we're in the middle of probing this record, we need to start again,
		// because changing its rdata may change the outcome of the tie-breaker.
		// (If the record type is kDNSRecordTypeUnique (unconfirmed unique) then DefaultProbeCountForRecordType is non-zero.)
		rr->ProbeCount     = DefaultProbeCountForRecordType(rr->resrec.RecordType);

		// If we've announced this record, we really should send a goodbye packet for the old rdata before
		// changing to the new rdata. However, in practice, we only do SetTargetToHostName for unique records,
		// so when we announce them we'll set the kDNSClass_UniqueRRSet and clear any stale data that way.
		if (rr->RequireGoodbye && rr->resrec.RecordType == kDNSRecordTypeShared)
			debugf("Have announced shared record %##s (%s) at least once: should have sent a goodbye packet before updating",
				rr->resrec.name->c, DNSTypeName(rr->resrec.rrtype));

		rr->AnnounceCount  = InitialAnnounceCount;
		rr->RequireGoodbye = mDNSfalse;
		InitializeLastAPTime(m, rr);
		}
	}

mDNSlocal void AcknowledgeRecord(mDNS *const m, AuthRecord *const rr)
	{
	if (rr->RecordCallback)
		{
		// CAUTION: MUST NOT do anything more with rr after calling rr->Callback(), because the client's callback function
		// is allowed to do anything, including starting/stopping queries, registering/deregistering records, etc.
		rr->Acknowledged = mDNStrue;
		mDNS_DropLockBeforeCallback();		// Allow client to legally make mDNS API calls from the callback
		rr->RecordCallback(m, rr, mStatus_NoError);
		mDNS_ReclaimLockAfterCallback();	// Decrement mDNS_reentrancy to block mDNS API calls again
		}
	}

mDNSexport void ActivateUnicastRegistration(mDNS *const m, AuthRecord *const rr)
	{
	// Make sure that we don't activate the SRV record and associated service records, if it is in
	// NoTarget state. First time when a service is being instantiated, SRV record may be in NoTarget state.
	// We should not activate any of the other reords (PTR, TXT) that are part of the service. When
	// the target becomes available, the records will be reregistered.
	if (rr->resrec.rrtype != kDNSType_SRV)
		{
		AuthRecord *srvRR = mDNSNULL;
		if (rr->resrec.rrtype == kDNSType_PTR)
			srvRR = rr->Additional1;
		else if (rr->resrec.rrtype == kDNSType_TXT)
			srvRR = rr->DependentOn;
		if (srvRR)
			{
			if (srvRR->resrec.rrtype != kDNSType_SRV)
				{
				LogMsg("ActivateUnicastRegistration: ERROR!! Resource record %s wrong, expecting SRV type", ARDisplayString(m, srvRR));
				}
			else
				{
				LogInfo("ActivateUnicastRegistration: Found Service Record %s in state %d for %##s (%s)",
					ARDisplayString(m, srvRR), srvRR->state, rr->resrec.name->c, DNSTypeName(rr->resrec.rrtype));
				rr->state = srvRR->state;
				}
			}
		}

	if (rr->state == regState_NoTarget)
		{
		LogInfo("ActivateUnicastRegistration record %s in regState_NoTarget, not activating", ARDisplayString(m, rr));
		return;
		}
	// When we wake up from sleep, we call ActivateUnicastRegistration. It is possible that just before we went to sleep,
	// the service/record was being deregistered. In that case, we should not try to register again. For the cases where
	// the records are deregistered due to e.g., no target for the SRV record, we would have returned from above if it
	// was already in NoTarget state. If it was in the process of deregistration but did not complete fully before we went
	// to sleep, then it is okay to start in Pending state as we will go back to NoTarget state if we don't have a target.
	if (rr->resrec.RecordType == kDNSRecordTypeDeregistering)
		{
		LogInfo("ActivateUnicastRegistration: Resource record %s, current state %d, moving to DeregPending", ARDisplayString(m, rr), rr->state);
		rr->state = regState_DeregPending;
		}
	else
		{
		LogInfo("ActivateUnicastRegistration: Resource record %s, current state %d, moving to Pending", ARDisplayString(m, rr), rr->state);
		rr->state = regState_Pending;
		}
	rr->ProbeCount     = 0;
	rr->AnnounceCount  = 0;
	rr->ThisAPInterval = INIT_RECORD_REG_INTERVAL;
	rr->LastAPTime     = m->timenow - rr->ThisAPInterval;
	rr->expire         = 0;	// Forget about all the leases, start fresh
	rr->uselease       = mDNStrue;
	rr->updateid       = zeroID;
	rr->SRVChanged     = mDNSfalse;
	rr->updateError    = mStatus_NoError;
	// RestartRecordGetZoneData calls this function whenever a new interface gets registered with core.
	// The records might already be registered with the server and hence could have NAT state.
	if (rr->NATinfo.clientContext)
		{
		mDNS_StopNATOperation_internal(m, &rr->NATinfo);
		rr->NATinfo.clientContext = mDNSNULL;
		}
	if (rr->nta) { CancelGetZoneData(m, rr->nta); rr->nta = mDNSNULL; }
	if (rr->tcp) { DisposeTCPConn(rr->tcp);       rr->tcp = mDNSNULL; }
	if (m->NextuDNSEvent - (rr->LastAPTime + rr->ThisAPInterval) >= 0)
		m->NextuDNSEvent = (rr->LastAPTime + rr->ThisAPInterval);
	}

// Two records qualify to be local duplicates if:
// (a) the RecordTypes are the same, or
// (b) one is Unique and the other Verified
// (c) either is in the process of deregistering
#define RecordLDT(A,B) ((A)->resrec.RecordType == (B)->resrec.RecordType || \
	((A)->resrec.RecordType | (B)->resrec.RecordType) == (kDNSRecordTypeUnique | kDNSRecordTypeVerified) || \
	((A)->resrec.RecordType == kDNSRecordTypeDeregistering || (B)->resrec.RecordType == kDNSRecordTypeDeregistering))

#define RecordIsLocalDuplicate(A,B) \
	((A)->resrec.InterfaceID == (B)->resrec.InterfaceID && RecordLDT((A),(B)) && IdenticalResourceRecord(&(A)->resrec, &(B)->resrec))

mDNSlocal AuthRecord *CheckAuthIdenticalRecord(AuthHash *r, AuthRecord *rr)
	{
	AuthGroup *a;
	AuthGroup **ag = &a;
	AuthRecord **rp;
	const mDNSu32 slot = AuthHashSlot(rr->resrec.name);

	a = AuthGroupForRecord(r, slot, &rr->resrec);
	if (!a) return mDNSNULL;
	rp = &(*ag)->members;
	while (*rp)
		{
		if (!RecordIsLocalDuplicate(*rp, rr))
			rp=&(*rp)->next;
		else
			{
			if ((*rp)->resrec.RecordType == kDNSRecordTypeDeregistering)
				{
				(*rp)->AnnounceCount = 0;
				rp=&(*rp)->next;
				}
			else return *rp;
			}
		}
	return (mDNSNULL);
	}

mDNSlocal mDNSBool CheckAuthRecordConflict(AuthHash *r, AuthRecord *rr)
	{
	AuthGroup *a;
	AuthGroup **ag = &a;
	AuthRecord **rp;
	const mDNSu32 slot = AuthHashSlot(rr->resrec.name);

	a = AuthGroupForRecord(r, slot, &rr->resrec);
	if (!a) return mDNSfalse;
	rp = &(*ag)->members;
	while (*rp)
		{
		const AuthRecord *s1 = rr->RRSet ? rr->RRSet : rr;
		const AuthRecord *s2 = (*rp)->RRSet ? (*rp)->RRSet : *rp;
		if (s1 != s2 && SameResourceRecordSignature((*rp), rr) && !IdenticalSameNameRecord(&(*rp)->resrec, &rr->resrec))
			return mDNStrue;
		else
			rp=&(*rp)->next;
		}
	return (mDNSfalse);
	}

// checks to see if "rr" is already present
mDNSlocal AuthRecord *CheckAuthSameRecord(AuthHash *r, AuthRecord *rr)
	{
	AuthGroup *a;
	AuthGroup **ag = &a;
	AuthRecord **rp;
	const mDNSu32 slot = AuthHashSlot(rr->resrec.name);

	a = AuthGroupForRecord(r, slot, &rr->resrec);
	if (!a) return mDNSNULL;
	rp = &(*ag)->members;
	while (*rp)
		{
		if (*rp != rr)
			rp=&(*rp)->next;
		else
			{
			return *rp;
			}
		}
	return (mDNSNULL);
	}

// Exported so uDNS.c can call this
mDNSexport mStatus mDNS_Register_internal(mDNS *const m, AuthRecord *const rr)
	{
	domainname *target = GetRRDomainNameTarget(&rr->resrec);
	AuthRecord *r;
	AuthRecord **p = &m->ResourceRecords;
	AuthRecord **d = &m->DuplicateRecords;

	if ((mDNSs32)rr->resrec.rroriginalttl <= 0)
		{ LogMsg("mDNS_Register_internal: TTL %X should be 1 - 0x7FFFFFFF %s", rr->resrec.rroriginalttl, ARDisplayString(m, rr)); return(mStatus_BadParamErr); }

	if (!rr->resrec.RecordType)
		{ LogMsg("mDNS_Register_internal: RecordType must be non-zero %s", ARDisplayString(m, rr)); return(mStatus_BadParamErr); }

	if (m->ShutdownTime)
		{ LogMsg("mDNS_Register_internal: Shutting down, can't register %s", ARDisplayString(m, rr)); return(mStatus_ServiceNotRunning); }

	if (m->DivertMulticastAdvertisements && !AuthRecord_uDNS(rr))
		{
		mDNSInterfaceID previousID = rr->resrec.InterfaceID;
		if (rr->resrec.InterfaceID == mDNSInterface_Any || rr->resrec.InterfaceID == mDNSInterface_P2P)
			{
			rr->resrec.InterfaceID = mDNSInterface_LocalOnly;
			rr->ARType = AuthRecordLocalOnly;
			}
		if (rr->resrec.InterfaceID != mDNSInterface_LocalOnly)
			{
			NetworkInterfaceInfo *intf = FirstInterfaceForID(m, rr->resrec.InterfaceID);
			if (intf && !intf->Advertise){ rr->resrec.InterfaceID = mDNSInterface_LocalOnly; rr->ARType = AuthRecordLocalOnly; }
			}
		if (rr->resrec.InterfaceID != previousID)
			LogInfo("mDNS_Register_internal: Diverting record to local-only %s", ARDisplayString(m, rr));
		}

	if (RRLocalOnly(rr))
		{
		if (CheckAuthSameRecord(&m->rrauth, rr))
			{
			LogMsg("mDNS_Register_internal: ERROR!! Tried to register LocalOnly AuthRecord %p %##s (%s) that's already in the list",
				rr, rr->resrec.name->c, DNSTypeName(rr->resrec.rrtype));
			return(mStatus_AlreadyRegistered);
			}
		}
	else
		{
		while (*p && *p != rr) p=&(*p)->next;
		if (*p)
			{
			LogMsg("mDNS_Register_internal: ERROR!! Tried to register AuthRecord %p %##s (%s) that's already in the list",
				rr, rr->resrec.name->c, DNSTypeName(rr->resrec.rrtype));
			return(mStatus_AlreadyRegistered);
			}
		}

	while (*d && *d != rr) d=&(*d)->next;
	if (*d)
		{
		LogMsg("mDNS_Register_internal: ERROR!! Tried to register AuthRecord %p %##s (%s) that's already in the Duplicate list",
				rr, rr->resrec.name->c, DNSTypeName(rr->resrec.rrtype));
		return(mStatus_AlreadyRegistered);
		}

	if (rr->DependentOn)
		{
		if (rr->resrec.RecordType == kDNSRecordTypeUnique)
			rr->resrec.RecordType =  kDNSRecordTypeVerified;
		else
			{
			LogMsg("mDNS_Register_internal: ERROR! %##s (%s): rr->DependentOn && RecordType != kDNSRecordTypeUnique",
				rr->resrec.name->c, DNSTypeName(rr->resrec.rrtype));
			return(mStatus_Invalid);
			}
		if (!(rr->DependentOn->resrec.RecordType & (kDNSRecordTypeUnique | kDNSRecordTypeVerified | kDNSRecordTypeKnownUnique)))
			{
			LogMsg("mDNS_Register_internal: ERROR! %##s (%s): rr->DependentOn->RecordType bad type %X",
				rr->resrec.name->c, DNSTypeName(rr->resrec.rrtype), rr->DependentOn->resrec.RecordType);
			return(mStatus_Invalid);
			}
		}

	// If this resource record is referencing a specific interface, make sure it exists.
	// Skip checks for LocalOnly and P2P as they are not valid InterfaceIDs. Also, for scoped
	// entries in /etc/hosts skip that check as that interface may not be valid at this time.
	if (rr->resrec.InterfaceID && rr->ARType != AuthRecordLocalOnly && rr->ARType != AuthRecordP2P)
		{
		NetworkInterfaceInfo *intf = FirstInterfaceForID(m, rr->resrec.InterfaceID);
		if (!intf)
			{
			debugf("mDNS_Register_internal: Bogus InterfaceID %p in resource record", rr->resrec.InterfaceID);
			return(mStatus_BadReferenceErr);
			}
		}

	rr->next = mDNSNULL;

	// Field Group 1: The actual information pertaining to this resource record
	// Set up by client prior to call

	// Field Group 2: Persistent metadata for Authoritative Records
//	rr->Additional1       = set to mDNSNULL  in mDNS_SetupResourceRecord; may be overridden by client
//	rr->Additional2       = set to mDNSNULL  in mDNS_SetupResourceRecord; may be overridden by client
//	rr->DependentOn       = set to mDNSNULL  in mDNS_SetupResourceRecord; may be overridden by client
//	rr->RRSet             = set to mDNSNULL  in mDNS_SetupResourceRecord; may be overridden by client
//	rr->Callback          = already set      in mDNS_SetupResourceRecord
//	rr->Context           = already set      in mDNS_SetupResourceRecord
//	rr->RecordType        = already set      in mDNS_SetupResourceRecord
//	rr->HostTarget        = set to mDNSfalse in mDNS_SetupResourceRecord; may be overridden by client
//	rr->AllowRemoteQuery  = set to mDNSfalse in mDNS_SetupResourceRecord; may be overridden by client
	// Make sure target is not uninitialized data, or we may crash writing debugging log messages
	if (rr->AutoTarget && target) target->c[0] = 0;

	// Field Group 3: Transient state for Authoritative Records
	rr->Acknowledged      = mDNSfalse;
	rr->ProbeCount        = DefaultProbeCountForRecordType(rr->resrec.RecordType);
	rr->AnnounceCount     = InitialAnnounceCount;
	rr->RequireGoodbye    = mDNSfalse;
	rr->AnsweredLocalQ    = mDNSfalse;
	rr->IncludeInProbe    = mDNSfalse;
	rr->ImmedUnicast      = mDNSfalse;
	rr->SendNSECNow       = mDNSNULL;
	rr->ImmedAnswer       = mDNSNULL;
	rr->ImmedAdditional   = mDNSNULL;
	rr->SendRNow          = mDNSNULL;
	rr->v4Requester       = zerov4Addr;
	rr->v6Requester       = zerov6Addr;
	rr->NextResponse      = mDNSNULL;
	rr->NR_AnswerTo       = mDNSNULL;
	rr->NR_AdditionalTo   = mDNSNULL;
	if (!rr->AutoTarget) InitializeLastAPTime(m, rr);
//	rr->LastAPTime        = Set for us in InitializeLastAPTime()
//	rr->LastMCTime        = Set for us in InitializeLastAPTime()
//	rr->LastMCInterface   = Set for us in InitializeLastAPTime()
	rr->NewRData          = mDNSNULL;
	rr->newrdlength       = 0;
	rr->UpdateCallback    = mDNSNULL;
	rr->UpdateCredits     = kMaxUpdateCredits;
	rr->NextUpdateCredit  = 0;
	rr->UpdateBlocked     = 0;

	// For records we're holding as proxy (except reverse-mapping PTR records) two announcements is sufficient
	if (rr->WakeUp.HMAC.l[0] && !rr->AddressProxy.type) rr->AnnounceCount = 2;

	// Field Group 4: Transient uDNS state for Authoritative Records
	rr->state             = regState_Zero;
	rr->uselease          = 0;
	rr->expire            = 0;
	rr->Private           = 0;
	rr->updateid          = zeroID;
	rr->zone              = rr->resrec.name;
	rr->nta               = mDNSNULL;
	rr->tcp               = mDNSNULL;
	rr->OrigRData         = 0;
	rr->OrigRDLen         = 0;
	rr->InFlightRData     = 0;
	rr->InFlightRDLen     = 0;
	rr->QueuedRData       = 0;
	rr->QueuedRDLen       = 0;
	//mDNSPlatformMemZero(&rr->NATinfo, sizeof(rr->NATinfo));
	// We should be recording the actual internal port for this service record here. Once we initiate our NAT mapping
	// request we'll subsequently overwrite srv.port with the allocated external NAT port -- potentially multiple
	// times with different values if the external NAT port changes during the lifetime of the service registration.
	//if (rr->resrec.rrtype == kDNSType_SRV) rr->NATinfo.IntPort = rr->resrec.rdata->u.srv.port;

//	rr->resrec.interface         = already set in mDNS_SetupResourceRecord
//	rr->resrec.name->c           = MUST be set by client
//	rr->resrec.rrtype            = already set in mDNS_SetupResourceRecord
//	rr->resrec.rrclass           = already set in mDNS_SetupResourceRecord
//	rr->resrec.rroriginalttl     = already set in mDNS_SetupResourceRecord
//	rr->resrec.rdata             = MUST be set by client, unless record type is CNAME or PTR and rr->HostTarget is set

	// BIND named (name daemon) doesn't allow TXT records with zero-length rdata. This is strictly speaking correct,
	// since RFC 1035 specifies a TXT record as "One or more <character-string>s", not "Zero or more <character-string>s".
	// Since some legacy apps try to create zero-length TXT records, we'll silently correct it here.
	if (rr->resrec.rrtype == kDNSType_TXT && rr->resrec.rdlength == 0) { rr->resrec.rdlength = 1; rr->resrec.rdata->u.txt.c[0] = 0; }

	if (rr->AutoTarget)
		{
		SetTargetToHostName(m, rr);	// Also sets rdlength and rdestimate for us, and calls InitializeLastAPTime();
#ifndef UNICAST_DISABLED
		// If we have no target record yet, SetTargetToHostName will set rr->state == regState_NoTarget
		// In this case we leave the record half-formed in the list, and later we'll remove it from the list and re-add it properly.
		if (rr->state == regState_NoTarget)
			{
			// Initialize the target so that we don't crash while logging etc.
			domainname *tar = GetRRDomainNameTarget(&rr->resrec);
			if (tar) tar->c[0] = 0;
			LogInfo("mDNS_Register_internal: record %s in NoTarget state", ARDisplayString(m, rr));
			}
#endif
		}
	else
		{
		rr->resrec.rdlength   = GetRDLength(&rr->resrec, mDNSfalse);
		rr->resrec.rdestimate = GetRDLength(&rr->resrec, mDNStrue);
		}

	if (!ValidateDomainName(rr->resrec.name))
		{ LogMsg("Attempt to register record with invalid name: %s", ARDisplayString(m, rr)); return(mStatus_Invalid); }

	// Don't do this until *after* we've set rr->resrec.rdlength
	if (!ValidateRData(rr->resrec.rrtype, rr->resrec.rdlength, rr->resrec.rdata))
		{ LogMsg("Attempt to register record with invalid rdata: %s", ARDisplayString(m, rr)); return(mStatus_Invalid); }

	rr->resrec.namehash   = DomainNameHashValue(rr->resrec.name);
	rr->resrec.rdatahash  = target ? DomainNameHashValue(target) : RDataHashValue(&rr->resrec);

	if (RRLocalOnly(rr))
		{
		// If this is supposed to be unique, make sure we don't have any name conflicts.
		// If we found a conflict, we may still want to insert the record in the list but mark it appropriately
		// (kDNSRecordTypeDeregistering) so that we deliver RMV events to the application. But this causes more
		// complications and not clear whether there are any benefits. See rdar:9304275 for details.
		// Hence, just bail out.
		if (rr->resrec.RecordType & kDNSRecordTypeUniqueMask)
			{
			if (CheckAuthRecordConflict(&m->rrauth, rr))
				{
				LogInfo("mDNS_Register_internal: Name conflict %s (%p), InterfaceID %p", ARDisplayString(m, rr), rr, rr->resrec.InterfaceID);
				return mStatus_NameConflict;
				}
			}
		}

	// For uDNS records, we don't support duplicate checks at this time.
#ifndef UNICAST_DISABLED
	if (AuthRecord_uDNS(rr))
		{
		if (!m->NewLocalRecords) m->NewLocalRecords = rr;
		// When we called SetTargetToHostName, it may have caused mDNS_Register_internal to be re-entered, appending new
		// records to the list, so we now need to update p to advance to the new end to the list before appending our new record.
		// Note that for AutoTunnel this should never happen, but this check makes the code future-proof.
		while (*p) p=&(*p)->next;
		*p = rr;
		if (rr->resrec.RecordType == kDNSRecordTypeUnique) rr->resrec.RecordType = kDNSRecordTypeVerified;
		rr->ProbeCount    = 0;
		rr->AnnounceCount = 0;
		if (rr->state != regState_NoTarget) ActivateUnicastRegistration(m, rr);
		return(mStatus_NoError);			// <--- Note: For unicast records, code currently bails out at this point
		}
#endif

	// Now that we've finished building our new record, make sure it's not identical to one we already have
	if (RRLocalOnly(rr))
		{
		rr->ProbeCount    = 0;
		rr->AnnounceCount = 0;
		r = CheckAuthIdenticalRecord(&m->rrauth, rr);
		}
	else
		{
		for (r = m->ResourceRecords; r; r=r->next)
			if (RecordIsLocalDuplicate(r, rr))
				{
				if (r->resrec.RecordType == kDNSRecordTypeDeregistering) r->AnnounceCount = 0;
				else break;
				}
		}

	if (r)
		{
		debugf("mDNS_Register_internal:Adding to duplicate list %s", ARDisplayString(m,rr));
		*d = rr;
		// If the previous copy of this record is already verified unique,
		// then indicate that we should move this record promptly to kDNSRecordTypeUnique state.
		// Setting ProbeCount to zero will cause SendQueries() to advance this record to
		// kDNSRecordTypeVerified state and call the client callback at the next appropriate time.
		if (rr->resrec.RecordType == kDNSRecordTypeUnique && r->resrec.RecordType == kDNSRecordTypeVerified)
			rr->ProbeCount = 0;
		}
	else
		{
		debugf("mDNS_Register_internal: Adding to active record list %s", ARDisplayString(m,rr));
		if (RRLocalOnly(rr))
			{
			AuthGroup *ag;
			ag = InsertAuthRecord(m, &m->rrauth, rr);
			if (ag && !ag->NewLocalOnlyRecords) {
				m->NewLocalOnlyRecords = mDNStrue;
				ag->NewLocalOnlyRecords = rr;
			}
			// No probing for LocalOnly records, Acknowledge them right away
			if (rr->resrec.RecordType == kDNSRecordTypeUnique) rr->resrec.RecordType = kDNSRecordTypeVerified;
			AcknowledgeRecord(m, rr);
			return(mStatus_NoError);
			}
		else
			{
			if (!m->NewLocalRecords) m->NewLocalRecords = rr;
			*p = rr;
			}
		}

	if (!AuthRecord_uDNS(rr))	// This check is superfluous, given that for unicast records we (currently) bail out above
		{
		// For records that are not going to probe, acknowledge them right away
		if (rr->resrec.RecordType != kDNSRecordTypeUnique && rr->resrec.RecordType != kDNSRecordTypeDeregistering)
			AcknowledgeRecord(m, rr);

		// Adding a record may affect whether or not we should sleep
		mDNS_UpdateAllowSleep(m);
		}

	return(mStatus_NoError);
	}

mDNSlocal void RecordProbeFailure(mDNS *const m, const AuthRecord *const rr)
	{
	m->ProbeFailTime = m->timenow;
	m->NumFailedProbes++;
	// If we've had fifteen or more probe failures, rate-limit to one every five seconds.
	// If a bunch of hosts have all been configured with the same name, then they'll all
	// conflict and run through the same series of names: name-2, name-3, name-4, etc.,
	// up to name-10. After that they'll start adding random increments in the range 1-100,
	// so they're more likely to branch out in the available namespace and settle on a set of
	// unique names quickly. If after five more tries the host is still conflicting, then we
	// may have a serious problem, so we start rate-limiting so we don't melt down the network.
	if (m->NumFailedProbes >= 15)
		{
		m->SuppressProbes = NonZeroTime(m->timenow + mDNSPlatformOneSecond * 5);
		LogMsg("Excessive name conflicts (%lu) for %##s (%s); rate limiting in effect",
			m->NumFailedProbes, rr->resrec.name->c, DNSTypeName(rr->resrec.rrtype));
		}
	}

mDNSlocal void CompleteRDataUpdate(mDNS *const m, AuthRecord *const rr)
	{
	RData *OldRData = rr->resrec.rdata;
	mDNSu16 OldRDLen = rr->resrec.rdlength;
	SetNewRData(&rr->resrec, rr->NewRData, rr->newrdlength);	// Update our rdata
	rr->NewRData = mDNSNULL;									// Clear the NewRData pointer ...
	if (rr->UpdateCallback)
		rr->UpdateCallback(m, rr, OldRData, OldRDLen);			// ... and let the client know
	}

// Note: mDNS_Deregister_internal can call a user callback, which may change the record list and/or question list.
// Any code walking either list must use the CurrentQuestion and/or CurrentRecord mechanism to protect against this.
// Exported so uDNS.c can call this
mDNSexport mStatus mDNS_Deregister_internal(mDNS *const m, AuthRecord *const rr, mDNS_Dereg_type drt)
	{
	AuthRecord *r2;
	mDNSu8 RecordType = rr->resrec.RecordType;
	AuthRecord **p = &m->ResourceRecords;	// Find this record in our list of active records
	mDNSBool dupList = mDNSfalse;

	if (RRLocalOnly(rr))
		{
		AuthGroup *a;
		AuthGroup **ag = &a;
		AuthRecord **rp;
		const mDNSu32 slot = AuthHashSlot(rr->resrec.name);

		a = AuthGroupForRecord(&m->rrauth, slot, &rr->resrec);
		if (!a) return mDNSfalse;
		rp = &(*ag)->members;
		while (*rp && *rp != rr) rp=&(*rp)->next;
		p = rp;
		}
	else
		{
		while (*p && *p != rr) p=&(*p)->next;
		}

	if (*p)
		{
		// We found our record on the main list. See if there are any duplicates that need special handling.
		if (drt == mDNS_Dereg_conflict)		// If this was a conflict, see that all duplicates get the same treatment
			{
			// Scan for duplicates of rr, and mark them for deregistration at the end of this routine, after we've finished
			// deregistering rr. We need to do this scan *before* we give the client the chance to free and reuse the rr memory.
			for (r2 = m->DuplicateRecords; r2; r2=r2->next) if (RecordIsLocalDuplicate(r2, rr)) r2->ProbeCount = 0xFF;
			}
		else
			{
			// Before we delete the record (and potentially send a goodbye packet)
			// first see if we have a record on the duplicate list ready to take over from it.
			AuthRecord **d = &m->DuplicateRecords;
			while (*d && !RecordIsLocalDuplicate(*d, rr)) d=&(*d)->next;
			if (*d)
				{
				AuthRecord *dup = *d;
				debugf("mDNS_Register_internal: Duplicate record %p taking over from %p %##s (%s)",
					dup, rr, rr->resrec.name->c, DNSTypeName(rr->resrec.rrtype));
				*d        = dup->next;		// Cut replacement record from DuplicateRecords list
				if (RRLocalOnly(rr))
					{
					dup->next = mDNSNULL;
					if (!InsertAuthRecord(m, &m->rrauth, dup)) LogMsg("mDNS_Deregister_internal: ERROR!! cannot insert %s", ARDisplayString(m, dup));
					}
				else
					{
					dup->next = rr->next;		// And then...
					rr->next  = dup;			// ... splice it in right after the record we're about to delete
					}
				dup->resrec.RecordType        = rr->resrec.RecordType;
				dup->ProbeCount      = rr->ProbeCount;
				dup->AnnounceCount   = rr->AnnounceCount;
				dup->RequireGoodbye  = rr->RequireGoodbye;
				dup->AnsweredLocalQ  = rr->AnsweredLocalQ;
				dup->ImmedAnswer     = rr->ImmedAnswer;
				dup->ImmedUnicast    = rr->ImmedUnicast;
				dup->ImmedAdditional = rr->ImmedAdditional;
				dup->v4Requester     = rr->v4Requester;
				dup->v6Requester     = rr->v6Requester;
				dup->ThisAPInterval  = rr->ThisAPInterval;
				dup->LastAPTime      = rr->LastAPTime;
				dup->LastMCTime      = rr->LastMCTime;
				dup->LastMCInterface = rr->LastMCInterface;
				dup->Private         = rr->Private;
				dup->state           = rr->state;
				rr->RequireGoodbye = mDNSfalse;
				rr->AnsweredLocalQ = mDNSfalse;
				}
			}
		}
	else
		{
		// We didn't find our record on the main list; try the DuplicateRecords list instead.
		p = &m->DuplicateRecords;
		while (*p && *p != rr) p=&(*p)->next;
		// If we found our record on the duplicate list, then make sure we don't send a goodbye for it
		if (*p) { rr->RequireGoodbye = mDNSfalse; dupList = mDNStrue; }
		if (*p) debugf("mDNS_Deregister_internal: Deleting DuplicateRecord %p %##s (%s)",
			rr, rr->resrec.name->c, DNSTypeName(rr->resrec.rrtype));
		}

	if (!*p)
		{
		// No need to log an error message if we already know this is a potentially repeated deregistration
		if (drt != mDNS_Dereg_repeat)
			LogMsg("mDNS_Deregister_internal: Record %p not found in list %s", rr, ARDisplayString(m,rr));
		return(mStatus_BadReferenceErr);
		}

	// If this is a shared record and we've announced it at least once,
	// we need to retract that announcement before we delete the record

	// If this is a record (including mDNSInterface_LocalOnly records) for which we've given local-only answers then
	// it's tempting to just do "AnswerAllLocalQuestionsWithLocalAuthRecord(m, rr, mDNSfalse)" here, but that would not not be safe.
	// The AnswerAllLocalQuestionsWithLocalAuthRecord routine walks the question list invoking client callbacks, using the "m->CurrentQuestion"
	// mechanism to cope with the client callback modifying the question list while that's happening.
	// However, mDNS_Deregister could have been called from a client callback (e.g. from the domain enumeration callback FoundDomain)
	// which means that the "m->CurrentQuestion" mechanism is already in use to protect that list, so we can't use it twice.
	// More generally, if we invoke callbacks from within a client callback, then those callbacks could deregister other
	// records, thereby invoking yet more callbacks, without limit.
	// The solution is to defer delivering the "Remove" events until mDNS_Execute time, just like we do for sending
	// actual goodbye packets.

#ifndef UNICAST_DISABLED
	if (AuthRecord_uDNS(rr))
		{
		if (rr->RequireGoodbye)
			{
			if (rr->tcp) { DisposeTCPConn(rr->tcp); rr->tcp = mDNSNULL; }
			rr->resrec.RecordType    = kDNSRecordTypeDeregistering;
			m->LocalRemoveEvents     = mDNStrue;
			uDNS_DeregisterRecord(m, rr);
			// At this point unconditionally we bail out
			// Either uDNS_DeregisterRecord will have completed synchronously, and called CompleteDeregistration,
			// which calls us back here with RequireGoodbye set to false, or it will have initiated the deregistration
			// process and will complete asynchronously. Either way we don't need to do anything more here.
			return(mStatus_NoError);
			}
		// Sometimes the records don't complete proper deregistration i.e., don't wait for a response
		// from the server. In that case, if the records have been part of a group update, clear the
		// state here. Some recors e.g., AutoTunnel gets reused without ever being completely initialized
		rr->updateid = zeroID;

		// We defer cleaning up NAT state only after sending goodbyes. This is important because
		// RecordRegistrationGotZoneData guards against creating NAT state if clientContext is non-NULL.
		// This happens today when we turn on/off interface where we get multiple network transitions
		// and RestartRecordGetZoneData triggers re-registration of the resource records even though
		// they may be in Registered state which causes NAT information to be setup multiple times. Defering
		// the cleanup here keeps clientContext non-NULL and hence prevents that. Note that cleaning up
		// NAT state here takes care of the case where we did not send goodbyes at all.
		if (rr->NATinfo.clientContext)
			{
			mDNS_StopNATOperation_internal(m, &rr->NATinfo);
			rr->NATinfo.clientContext = mDNSNULL;
			}
		if (rr->nta) { CancelGetZoneData(m, rr->nta); rr->nta = mDNSNULL; }
		if (rr->tcp) { DisposeTCPConn(rr->tcp);       rr->tcp = mDNSNULL; }
		}
#endif // UNICAST_DISABLED

	if      (RecordType == kDNSRecordTypeUnregistered)
		LogMsg("mDNS_Deregister_internal: %s already marked kDNSRecordTypeUnregistered", ARDisplayString(m, rr));
	else if (RecordType == kDNSRecordTypeDeregistering)
		{
		LogMsg("mDNS_Deregister_internal: %s already marked kDNSRecordTypeDeregistering", ARDisplayString(m, rr));
		return(mStatus_BadReferenceErr);
		}

	// <rdar://problem/7457925> Local-only questions don't get remove events for unique records
	// We may want to consider changing this code so that we generate local-only question "rmv"
	// events (and maybe goodbye packets too) for unique records as well as for shared records
	// Note: If we change the logic for this "if" statement, need to ensure that the code in
	// CompleteDeregistration() sets the appropriate state variables to gaurantee that "else"
	// clause will execute here and the record will be cut from the list.
	if (rr->WakeUp.HMAC.l[0] ||
		(RecordType == kDNSRecordTypeShared && (rr->RequireGoodbye || rr->AnsweredLocalQ)))
		{
		verbosedebugf("mDNS_Deregister_internal: Starting deregistration for %s", ARDisplayString(m, rr));
		rr->resrec.RecordType    = kDNSRecordTypeDeregistering;
		rr->resrec.rroriginalttl = 0;
		rr->AnnounceCount        = rr->WakeUp.HMAC.l[0] ? WakeupCount : (drt == mDNS_Dereg_rapid) ? 1 : GoodbyeCount;
		rr->ThisAPInterval       = mDNSPlatformOneSecond * 2;
		rr->LastAPTime           = m->timenow - rr->ThisAPInterval;
		m->LocalRemoveEvents     = mDNStrue;
		if (m->NextScheduledResponse - (m->timenow + mDNSPlatformOneSecond/10) >= 0)
			m->NextScheduledResponse = (m->timenow + mDNSPlatformOneSecond/10);
		}
	else
		{
		if (!dupList && RRLocalOnly(rr))
			{
			AuthGroup *ag = RemoveAuthRecord(m, &m->rrauth, rr);
			if (ag->NewLocalOnlyRecords == rr) ag->NewLocalOnlyRecords = rr->next;
			}
		else
			{
			*p = rr->next;					// Cut this record from the list
			if (m->NewLocalRecords == rr) m->NewLocalRecords = rr->next;
			}
		// If someone is about to look at this, bump the pointer forward
		if (m->CurrentRecord   == rr) m->CurrentRecord   = rr->next;
		rr->next = mDNSNULL;

		// Should we generate local remove events here?
		// i.e. something like:
		// if (rr->AnsweredLocalQ) { AnswerAllLocalQuestionsWithLocalAuthRecord(m, rr, mDNSfalse); rr->AnsweredLocalQ = mDNSfalse; }

		verbosedebugf("mDNS_Deregister_internal: Deleting record for %s", ARDisplayString(m, rr));
		rr->resrec.RecordType = kDNSRecordTypeUnregistered;

		if ((drt == mDNS_Dereg_conflict || drt == mDNS_Dereg_repeat) && RecordType == kDNSRecordTypeShared)
			debugf("mDNS_Deregister_internal: Cannot have a conflict on a shared record! %##s (%s)",
				rr->resrec.name->c, DNSTypeName(rr->resrec.rrtype));

		// If we have an update queued up which never executed, give the client a chance to free that memory
		if (rr->NewRData) CompleteRDataUpdate(m, rr);	// Update our rdata, clear the NewRData pointer, and return memory to the client


		// CAUTION: MUST NOT do anything more with rr after calling rr->Callback(), because the client's callback function
		// is allowed to do anything, including starting/stopping queries, registering/deregistering records, etc.
		// In this case the likely client action to the mStatus_MemFree message is to free the memory,
		// so any attempt to touch rr after this is likely to lead to a crash.
		if (drt != mDNS_Dereg_conflict)
			{
			mDNS_DropLockBeforeCallback();		// Allow client to legally make mDNS API calls from the callback
			LogInfo("mDNS_Deregister_internal: mStatus_MemFree for %s", ARDisplayString(m, rr));
			if (rr->RecordCallback)
				rr->RecordCallback(m, rr, mStatus_MemFree);			// MUST NOT touch rr after this
			mDNS_ReclaimLockAfterCallback();	// Decrement mDNS_reentrancy to block mDNS API calls again
			}
		else
			{
			RecordProbeFailure(m, rr);
			mDNS_DropLockBeforeCallback();		// Allow client to legally make mDNS API calls from the callback
			if (rr->RecordCallback)
				rr->RecordCallback(m, rr, mStatus_NameConflict);	// MUST NOT touch rr after this
			mDNS_ReclaimLockAfterCallback();	// Decrement mDNS_reentrancy to block mDNS API calls again
			// Now that we've finished deregistering rr, check our DuplicateRecords list for any that we marked previously.
			// Note that with all the client callbacks going on, by the time we get here all the
			// records we marked may have been explicitly deregistered by the client anyway.
			r2 = m->DuplicateRecords;
			while (r2)
				{
				if (r2->ProbeCount != 0xFF) r2 = r2->next;
				else { mDNS_Deregister_internal(m, r2, mDNS_Dereg_conflict); r2 = m->DuplicateRecords; }
				}
			}
		}
	mDNS_UpdateAllowSleep(m);
	return(mStatus_NoError);
	}

// ***************************************************************************
#if COMPILER_LIKES_PRAGMA_MARK
#pragma mark -
#pragma mark - Packet Sending Functions
#endif

mDNSlocal void AddRecordToResponseList(AuthRecord ***nrpp, AuthRecord *rr, AuthRecord *add)
	{
	if (rr->NextResponse == mDNSNULL && *nrpp != &rr->NextResponse)
		{
		**nrpp = rr;
		// NR_AdditionalTo must point to a record with NR_AnswerTo set (and not NR_AdditionalTo)
		// If 'add' does not meet this requirement, then follow its NR_AdditionalTo pointer to a record that does
		// The referenced record will definitely be acceptable (by recursive application of this rule)
		if (add && add->NR_AdditionalTo) add = add->NR_AdditionalTo;
		rr->NR_AdditionalTo = add;
		*nrpp = &rr->NextResponse;
		}
	debugf("AddRecordToResponseList: %##s (%s) already in list", rr->resrec.name->c, DNSTypeName(rr->resrec.rrtype));
	}

mDNSlocal void AddAdditionalsToResponseList(mDNS *const m, AuthRecord *ResponseRecords, AuthRecord ***nrpp, const mDNSInterfaceID InterfaceID)
	{
	AuthRecord  *rr, *rr2;
	for (rr=ResponseRecords; rr; rr=rr->NextResponse)			// For each record we plan to put
		{
		// (Note: This is an "if", not a "while". If we add a record, we'll find it again
		// later in the "for" loop, and we will follow further "additional" links then.)
		if (rr->Additional1 && ResourceRecordIsValidInterfaceAnswer(rr->Additional1, InterfaceID))
			AddRecordToResponseList(nrpp, rr->Additional1, rr);

		if (rr->Additional2 && ResourceRecordIsValidInterfaceAnswer(rr->Additional2, InterfaceID))
			AddRecordToResponseList(nrpp, rr->Additional2, rr);

		// For SRV records, automatically add the Address record(s) for the target host
		if (rr->resrec.rrtype == kDNSType_SRV)
			{
			for (rr2=m->ResourceRecords; rr2; rr2=rr2->next)					// Scan list of resource records
				if (RRTypeIsAddressType(rr2->resrec.rrtype) &&					// For all address records (A/AAAA) ...
					ResourceRecordIsValidInterfaceAnswer(rr2, InterfaceID) &&	// ... which are valid for answer ...
					rr->resrec.rdatahash == rr2->resrec.namehash &&			// ... whose name is the name of the SRV target
					SameDomainName(&rr->resrec.rdata->u.srv.target, rr2->resrec.name))
					AddRecordToResponseList(nrpp, rr2, rr);
			}
		else if (RRTypeIsAddressType(rr->resrec.rrtype))	// For A or AAAA, put counterpart as additional
			{
			for (rr2=m->ResourceRecords; rr2; rr2=rr2->next)					// Scan list of resource records
				if (RRTypeIsAddressType(rr2->resrec.rrtype) &&					// For all address records (A/AAAA) ...
					ResourceRecordIsValidInterfaceAnswer(rr2, InterfaceID) &&	// ... which are valid for answer ...
					rr->resrec.namehash == rr2->resrec.namehash &&				// ... and have the same name
					SameDomainName(rr->resrec.name, rr2->resrec.name))
					AddRecordToResponseList(nrpp, rr2, rr);
			}
		else if (rr->resrec.rrtype == kDNSType_PTR)			// For service PTR, see if we want to add DeviceInfo record
			{
			if (ResourceRecordIsValidInterfaceAnswer(&m->DeviceInfo, InterfaceID) &&
				SameDomainLabel(rr->resrec.rdata->u.name.c, m->DeviceInfo.resrec.name->c))
				AddRecordToResponseList(nrpp, &m->DeviceInfo, rr);
			}
		}
	}

mDNSlocal void SendDelayedUnicastResponse(mDNS *const m, const mDNSAddr *const dest, const mDNSInterfaceID InterfaceID)
	{
	AuthRecord *rr;
	AuthRecord  *ResponseRecords = mDNSNULL;
	AuthRecord **nrp             = &ResponseRecords;
	NetworkInterfaceInfo *intf = FirstInterfaceForID(m, InterfaceID);

	// Make a list of all our records that need to be unicast to this destination
	for (rr = m->ResourceRecords; rr; rr=rr->next)
		{
		// If we find we can no longer unicast this answer, clear ImmedUnicast
		if (rr->ImmedAnswer == mDNSInterfaceMark               ||
			mDNSSameIPv4Address(rr->v4Requester, onesIPv4Addr) ||
			mDNSSameIPv6Address(rr->v6Requester, onesIPv6Addr)  )
			rr->ImmedUnicast = mDNSfalse;

		if (rr->ImmedUnicast && rr->ImmedAnswer == InterfaceID)
			{
			if ((dest->type == mDNSAddrType_IPv4 && mDNSSameIPv4Address(rr->v4Requester, dest->ip.v4)) ||
				(dest->type == mDNSAddrType_IPv6 && mDNSSameIPv6Address(rr->v6Requester, dest->ip.v6)))
				{
				rr->ImmedAnswer  = mDNSNULL;				// Clear the state fields
				rr->ImmedUnicast = mDNSfalse;
				rr->v4Requester  = zerov4Addr;
				rr->v6Requester  = zerov6Addr;

				// Only sent records registered for P2P over P2P interfaces
				if (intf && !mDNSPlatformValidRecordForInterface(rr, intf))
					{
					LogInfo("SendDelayedUnicastResponse: Not sending %s, on %s", ARDisplayString(m, rr), InterfaceNameForID(m, InterfaceID));
					continue;
					}

				if (rr->NextResponse == mDNSNULL && nrp != &rr->NextResponse)	// rr->NR_AnswerTo
					{ rr->NR_AnswerTo = (mDNSu8*)~0; *nrp = rr; nrp = &rr->NextResponse; }
				}
			}
		}

	AddAdditionalsToResponseList(m, ResponseRecords, &nrp, InterfaceID);

	while (ResponseRecords)
		{
		mDNSu8 *responseptr = m->omsg.data;
		mDNSu8 *newptr;
		InitializeDNSMessage(&m->omsg.h, zeroID, ResponseFlags);

		// Put answers in the packet
		while (ResponseRecords && ResponseRecords->NR_AnswerTo)
			{
			rr = ResponseRecords;
			if (rr->resrec.RecordType & kDNSRecordTypeUniqueMask)
				rr->resrec.rrclass |= kDNSClass_UniqueRRSet;		// Temporarily set the cache flush bit so PutResourceRecord will set it
			newptr = PutResourceRecord(&m->omsg, responseptr, &m->omsg.h.numAnswers, &rr->resrec);
			rr->resrec.rrclass &= ~kDNSClass_UniqueRRSet;			// Make sure to clear cache flush bit back to normal state
			if (!newptr && m->omsg.h.numAnswers) break;	// If packet full, send it now
			if (newptr) responseptr = newptr;
			ResponseRecords = rr->NextResponse;
			rr->NextResponse    = mDNSNULL;
			rr->NR_AnswerTo     = mDNSNULL;
			rr->NR_AdditionalTo = mDNSNULL;
			rr->RequireGoodbye  = mDNStrue;
			}

		// Add additionals, if there's space
		while (ResponseRecords && !ResponseRecords->NR_AnswerTo)
			{
			rr = ResponseRecords;
			if (rr->resrec.RecordType & kDNSRecordTypeUniqueMask)
				rr->resrec.rrclass |= kDNSClass_UniqueRRSet;		// Temporarily set the cache flush bit so PutResourceRecord will set it
			newptr = PutResourceRecord(&m->omsg, responseptr, &m->omsg.h.numAdditionals, &rr->resrec);
			rr->resrec.rrclass &= ~kDNSClass_UniqueRRSet;			// Make sure to clear cache flush bit back to normal state

			if (newptr) responseptr = newptr;
			if (newptr && m->omsg.h.numAnswers) rr->RequireGoodbye = mDNStrue;
			else if (rr->resrec.RecordType & kDNSRecordTypeUniqueMask) rr->ImmedAnswer = mDNSInterfaceMark;
			ResponseRecords = rr->NextResponse;
			rr->NextResponse    = mDNSNULL;
			rr->NR_AnswerTo     = mDNSNULL;
			rr->NR_AdditionalTo = mDNSNULL;
			}

		if (m->omsg.h.numAnswers)
			mDNSSendDNSMessage(m, &m->omsg, responseptr, InterfaceID, mDNSNULL, dest, MulticastDNSPort, mDNSNULL, mDNSNULL);
		}
	}

// CompleteDeregistration guarantees that on exit the record will have been cut from the m->ResourceRecords list
// and the client's mStatus_MemFree callback will have been invoked
mDNSexport void CompleteDeregistration(mDNS *const m, AuthRecord *rr)
	{
	LogInfo("CompleteDeregistration: called for Resource record %s", ARDisplayString(m, rr));
	// Clearing rr->RequireGoodbye signals mDNS_Deregister_internal() that
	// it should go ahead and immediately dispose of this registration
	rr->resrec.RecordType = kDNSRecordTypeShared;
	rr->RequireGoodbye    = mDNSfalse;
	rr->WakeUp.HMAC       = zeroEthAddr;
	if (rr->AnsweredLocalQ) { AnswerAllLocalQuestionsWithLocalAuthRecord(m, rr, mDNSfalse); rr->AnsweredLocalQ = mDNSfalse; }
	mDNS_Deregister_internal(m, rr, mDNS_Dereg_normal);		// Don't touch rr after this
	}

// DiscardDeregistrations is used on shutdown and sleep to discard (forcibly and immediately)
// any deregistering records that remain in the m->ResourceRecords list.
// DiscardDeregistrations calls mDNS_Deregister_internal which can call a user callback,
// which may change the record list and/or question list.
// Any code walking either list must use the CurrentQuestion and/or CurrentRecord mechanism to protect against this.
mDNSlocal void DiscardDeregistrations(mDNS *const m)
	{
	if (m->CurrentRecord)
		LogMsg("DiscardDeregistrations ERROR m->CurrentRecord already set %s", ARDisplayString(m, m->CurrentRecord));
	m->CurrentRecord = m->ResourceRecords;

	while (m->CurrentRecord)
		{
		AuthRecord *rr = m->CurrentRecord;
		if (!AuthRecord_uDNS(rr) && rr->resrec.RecordType == kDNSRecordTypeDeregistering)
			CompleteDeregistration(m, rr);		// Don't touch rr after this
		else
			m->CurrentRecord = rr->next;
		}
	}

mDNSlocal mStatus GetLabelDecimalValue(const mDNSu8 *const src, mDNSu8 *dst)
	{
	int i, val = 0;
	if (src[0] < 1 || src[0] > 3) return(mStatus_Invalid);
	for (i=1; i<=src[0]; i++)
		{
		if (src[i] < '0' || src[i] > '9') return(mStatus_Invalid);
		val = val * 10 + src[i] - '0';
		}
	if (val > 255) return(mStatus_Invalid);
	*dst = (mDNSu8)val;
	return(mStatus_NoError);
	}

mDNSlocal mStatus GetIPv4FromName(mDNSAddr *const a, const domainname *const name)
	{
	int skip = CountLabels(name) - 6;
	if (skip < 0) { LogMsg("GetIPFromName: Need six labels in IPv4 reverse mapping name %##s", name); return mStatus_Invalid; }
	if (GetLabelDecimalValue(SkipLeadingLabels(name, skip+3)->c, &a->ip.v4.b[0]) ||
		GetLabelDecimalValue(SkipLeadingLabels(name, skip+2)->c, &a->ip.v4.b[1]) ||
		GetLabelDecimalValue(SkipLeadingLabels(name, skip+1)->c, &a->ip.v4.b[2]) ||
		GetLabelDecimalValue(SkipLeadingLabels(name, skip+0)->c, &a->ip.v4.b[3])) return mStatus_Invalid;
	a->type = mDNSAddrType_IPv4;
	return(mStatus_NoError);
	}

#define HexVal(X) ( ((X) >= '0' && (X) <= '9') ? ((X) - '0'     ) :   \
					((X) >= 'A' && (X) <= 'F') ? ((X) - 'A' + 10) :   \
					((X) >= 'a' && (X) <= 'f') ? ((X) - 'a' + 10) : -1)

mDNSlocal mStatus GetIPv6FromName(mDNSAddr *const a, const domainname *const name)
	{
	int i, h, l;
	const domainname *n;

	int skip = CountLabels(name) - 34;
	if (skip < 0) { LogMsg("GetIPFromName: Need 34 labels in IPv6 reverse mapping name %##s", name); return mStatus_Invalid; }

	n = SkipLeadingLabels(name, skip);
	for (i=0; i<16; i++)
		{
		if (n->c[0] != 1) return mStatus_Invalid;
		l = HexVal(n->c[1]);
		n = (const domainname *)(n->c + 2);

		if (n->c[0] != 1) return mStatus_Invalid;
		h = HexVal(n->c[1]);
		n = (const domainname *)(n->c + 2);

		if (l<0 || h<0) return mStatus_Invalid;
		a->ip.v6.b[15-i] = (mDNSu8)((h << 4) | l);
		}

	a->type = mDNSAddrType_IPv6;
	return(mStatus_NoError);
	}

mDNSlocal mDNSs32 ReverseMapDomainType(const domainname *const name)
	{
	int skip = CountLabels(name) - 2;
	if (skip >= 0)
		{
		const domainname *suffix = SkipLeadingLabels(name, skip);
		if (SameDomainName(suffix, (const domainname*)"\x7" "in-addr" "\x4" "arpa")) return mDNSAddrType_IPv4;
		if (SameDomainName(suffix, (const domainname*)"\x3" "ip6"     "\x4" "arpa")) return mDNSAddrType_IPv6;
		}
	return(mDNSAddrType_None);
	}

mDNSlocal void SendARP(mDNS *const m, const mDNSu8 op, const AuthRecord *const rr,
	const mDNSv4Addr *const spa, const mDNSEthAddr *const tha, const mDNSv4Addr *const tpa, const mDNSEthAddr *const dst)
	{
	int i;
	mDNSu8 *ptr = m->omsg.data;
	NetworkInterfaceInfo *intf = FirstInterfaceForID(m, rr->resrec.InterfaceID);
	if (!intf) { LogMsg("SendARP: No interface with InterfaceID %p found %s", rr->resrec.InterfaceID, ARDisplayString(m,rr)); return; }

	// 0x00 Destination address
	for (i=0; i<6; i++) *ptr++ = dst->b[i];

	// 0x06 Source address (Note: Since we don't currently set the BIOCSHDRCMPLT option, BPF will fill in the real interface address for us)
	for (i=0; i<6; i++) *ptr++ = intf->MAC.b[0];

	// 0x0C ARP Ethertype (0x0806)
	*ptr++ = 0x08; *ptr++ = 0x06;

	// 0x0E ARP header
	*ptr++ = 0x00; *ptr++ = 0x01;	// Hardware address space; Ethernet = 1
	*ptr++ = 0x08; *ptr++ = 0x00;	// Protocol address space; IP = 0x0800
	*ptr++ = 6;						// Hardware address length
	*ptr++ = 4;						// Protocol address length
	*ptr++ = 0x00; *ptr++ = op;		// opcode; Request = 1, Response = 2

	// 0x16 Sender hardware address (our MAC address)
	for (i=0; i<6; i++) *ptr++ = intf->MAC.b[i];

	// 0x1C Sender protocol address
	for (i=0; i<4; i++) *ptr++ = spa->b[i];

	// 0x20 Target hardware address
	for (i=0; i<6; i++) *ptr++ = tha->b[i];

	// 0x26 Target protocol address
	for (i=0; i<4; i++) *ptr++ = tpa->b[i];

	// 0x2A Total ARP Packet length 42 bytes
	mDNSPlatformSendRawPacket(m->omsg.data, ptr, rr->resrec.InterfaceID);
	}

mDNSlocal mDNSu16 CheckSum(const void *const data, mDNSs32 length, mDNSu32 sum)
	{
	const mDNSu16 *ptr = data;
	while (length > 0) { length -= 2; sum += *ptr++; }
	sum = (sum & 0xFFFF) + (sum >> 16);
	sum = (sum & 0xFFFF) + (sum >> 16);
	return(sum != 0xFFFF ? sum : 0);
	}

mDNSlocal mDNSu16 IPv6CheckSum(const mDNSv6Addr *const src, const mDNSv6Addr *const dst, const mDNSu8 protocol, const void *const data, const mDNSu32 length)
	{
	IPv6PseudoHeader ph;
	ph.src = *src;
	ph.dst = *dst;
	ph.len.b[0] = length >> 24;
	ph.len.b[1] = length >> 16;
	ph.len.b[2] = length >> 8;
	ph.len.b[3] = length;
	ph.pro.b[0] = 0;
	ph.pro.b[1] = 0;
	ph.pro.b[2] = 0;
	ph.pro.b[3] = protocol;
	return CheckSum(&ph, sizeof(ph), CheckSum(data, length, 0));
	}

mDNSlocal void SendNDP(mDNS *const m, const mDNSu8 op, const mDNSu8 flags, const AuthRecord *const rr,
	const mDNSv6Addr *const spa, const mDNSEthAddr *const tha, const mDNSv6Addr *const tpa, const mDNSEthAddr *const dst)
	{
	int i;
	mDNSOpaque16 checksum;
	mDNSu8 *ptr = m->omsg.data;
	// Some recipient hosts seem to ignore Neighbor Solicitations if the IPv6-layer destination address is not the
	// appropriate IPv6 solicited node multicast address, so we use that IPv6-layer destination address, even though
	// at the Ethernet-layer we unicast the packet to the intended target, to avoid wasting network bandwidth.
	const mDNSv6Addr mc = { { 0xFF,0x02,0x00,0x00, 0,0,0,0, 0,0,0,1, 0xFF,tpa->b[0xD],tpa->b[0xE],tpa->b[0xF] } };
	const mDNSv6Addr *const v6dst = (op == NDP_Sol) ? &mc : tpa;
	NetworkInterfaceInfo *intf = FirstInterfaceForID(m, rr->resrec.InterfaceID);
	if (!intf) { LogMsg("SendNDP: No interface with InterfaceID %p found %s", rr->resrec.InterfaceID, ARDisplayString(m,rr)); return; }

	// 0x00 Destination address
	for (i=0; i<6; i++) *ptr++ = dst->b[i];
	// Right now we only send Neighbor Solicitations to verify whether the host we're proxying for has gone to sleep yet.
	// Since we know who we're looking for, we send it via Ethernet-layer unicast, rather than bothering every host on the
	// link with a pointless link-layer multicast.
	// Should we want to send traditional Neighbor Solicitations in the future, where we really don't know in advance what
	// Ethernet-layer address we're looking for, we'll need to send to the appropriate Ethernet-layer multicast address:
	// *ptr++ = 0x33;
	// *ptr++ = 0x33;
	// *ptr++ = 0xFF;
	// *ptr++ = tpa->b[0xD];
	// *ptr++ = tpa->b[0xE];
	// *ptr++ = tpa->b[0xF];

	// 0x06 Source address (Note: Since we don't currently set the BIOCSHDRCMPLT option, BPF will fill in the real interface address for us)
	for (i=0; i<6; i++) *ptr++ = (tha ? *tha : intf->MAC).b[i];

	// 0x0C IPv6 Ethertype (0x86DD)
	*ptr++ = 0x86; *ptr++ = 0xDD;

	// 0x0E IPv6 header
	*ptr++ = 0x60; *ptr++ = 0x00; *ptr++ = 0x00; *ptr++ = 0x00;		// Version, Traffic Class, Flow Label
	*ptr++ = 0x00; *ptr++ = 0x20;									// Length
	*ptr++ = 0x3A;													// Protocol == ICMPv6
	*ptr++ = 0xFF;													// Hop Limit

	// 0x16 Sender IPv6 address
	for (i=0; i<16; i++) *ptr++ = spa->b[i];

	// 0x26 Destination IPv6 address
	for (i=0; i<16; i++) *ptr++ = v6dst->b[i];

	// 0x36 NDP header
	*ptr++ = op;					// 0x87 == Neighbor Solicitation, 0x88 == Neighbor Advertisement
	*ptr++ = 0x00;					// Code
	*ptr++ = 0x00; *ptr++ = 0x00;	// Checksum placeholder (0x38, 0x39)
	*ptr++ = flags;
	*ptr++ = 0x00; *ptr++ = 0x00; *ptr++ = 0x00;

	if (op == NDP_Sol)	// Neighbor Solicitation. The NDP "target" is the address we seek.
		{
		// 0x3E NDP target.
		for (i=0; i<16; i++) *ptr++ = tpa->b[i];
		// 0x4E Source Link-layer Address
		// <http://www.ietf.org/rfc/rfc2461.txt>
		// MUST NOT be included when the source IP address is the unspecified address.
		// Otherwise, on link layers that have addresses this option MUST be included
		// in multicast solicitations and SHOULD be included in unicast solicitations.
		if (!mDNSIPv6AddressIsZero(*spa))
			{
			*ptr++ = NDP_SrcLL;	// Option Type 1 == Source Link-layer Address
			*ptr++ = 0x01;		// Option length 1 (in units of 8 octets)
			for (i=0; i<6; i++) *ptr++ = (tha ? *tha : intf->MAC).b[i];
			}
		}
	else			// Neighbor Advertisement. The NDP "target" is the address we're giving information about.
		{
		// 0x3E NDP target.
		for (i=0; i<16; i++) *ptr++ = spa->b[i];
		// 0x4E Target Link-layer Address
		*ptr++ = NDP_TgtLL;	// Option Type 2 == Target Link-layer Address
		*ptr++ = 0x01;		// Option length 1 (in units of 8 octets)
		for (i=0; i<6; i++) *ptr++ = (tha ? *tha : intf->MAC).b[i];
		}

	// 0x4E or 0x56 Total NDP Packet length 78 or 86 bytes
	m->omsg.data[0x13] = ptr - &m->omsg.data[0x36];		// Compute actual length
	checksum.NotAnInteger = ~IPv6CheckSum(spa, v6dst, 0x3A, &m->omsg.data[0x36], m->omsg.data[0x13]);
	m->omsg.data[0x38] = checksum.b[0];
	m->omsg.data[0x39] = checksum.b[1];

	mDNSPlatformSendRawPacket(m->omsg.data, ptr, rr->resrec.InterfaceID);
	}

mDNSlocal void SetupOwnerOpt(const mDNS *const m, const NetworkInterfaceInfo *const intf, rdataOPT *const owner)
	{
	owner->u.owner.vers     = 0;
	owner->u.owner.seq      = m->SleepSeqNum;
	owner->u.owner.HMAC     = m->PrimaryMAC;
	owner->u.owner.IMAC     = intf->MAC;
	owner->u.owner.password = zeroEthAddr;

	// Don't try to compute the optlen until *after* we've set up the data fields
	// Right now the DNSOpt_Owner_Space macro does not depend on the owner->u.owner being set up correctly, but in the future it might
	owner->opt              = kDNSOpt_Owner;
	owner->optlen           = DNSOpt_Owner_Space(&m->PrimaryMAC, &intf->MAC) - 4;
	}

mDNSlocal void GrantUpdateCredit(AuthRecord *rr)
	{
	if (++rr->UpdateCredits >= kMaxUpdateCredits) rr->NextUpdateCredit = 0;
	else rr->NextUpdateCredit = NonZeroTime(rr->NextUpdateCredit + kUpdateCreditRefreshInterval);
	}

// Note about acceleration of announcements to facilitate automatic coalescing of
// multiple independent threads of announcements into a single synchronized thread:
// The announcements in the packet may be at different stages of maturity;
// One-second interval, two-second interval, four-second interval, and so on.
// After we've put in all the announcements that are due, we then consider
// whether there are other nearly-due announcements that are worth accelerating.
// To be eligible for acceleration, a record MUST NOT be older (further along
// its timeline) than the most mature record we've already put in the packet.
// In other words, younger records can have their timelines accelerated to catch up
// with their elder bretheren; this narrows the age gap and helps them eventually get in sync.
// Older records cannot have their timelines accelerated; this would just widen
// the gap between them and their younger bretheren and get them even more out of sync.

// Note: SendResponses calls mDNS_Deregister_internal which can call a user callback, which may change
// the record list and/or question list.
// Any code walking either list must use the CurrentQuestion and/or CurrentRecord mechanism to protect against this.
mDNSlocal void SendResponses(mDNS *const m)
	{
	int pktcount = 0;
	AuthRecord *rr, *r2;
	mDNSs32 maxExistingAnnounceInterval = 0;
	const NetworkInterfaceInfo *intf = GetFirstActiveInterface(m->HostInterfaces);

	m->NextScheduledResponse = m->timenow + 0x78000000;

	if (m->SleepState == SleepState_Transferring) RetrySPSRegistrations(m);

	for (rr = m->ResourceRecords; rr; rr=rr->next)
		if (rr->ImmedUnicast)
			{
			mDNSAddr v4 = { mDNSAddrType_IPv4, {{{0}}} };
			mDNSAddr v6 = { mDNSAddrType_IPv6, {{{0}}} };
			v4.ip.v4 = rr->v4Requester;
			v6.ip.v6 = rr->v6Requester;
			if (!mDNSIPv4AddressIsZero(rr->v4Requester)) SendDelayedUnicastResponse(m, &v4, rr->ImmedAnswer);
			if (!mDNSIPv6AddressIsZero(rr->v6Requester)) SendDelayedUnicastResponse(m, &v6, rr->ImmedAnswer);
			if (rr->ImmedUnicast)
				{
				LogMsg("SendResponses: ERROR: rr->ImmedUnicast still set: %s", ARDisplayString(m, rr));
				rr->ImmedUnicast = mDNSfalse;
				}
			}

	// ***
	// *** 1. Setup: Set the SendRNow and ImmedAnswer fields to indicate which interface(s) the records need to be sent on
	// ***

	// Run through our list of records, and decide which ones we're going to announce on all interfaces
	for (rr = m->ResourceRecords; rr; rr=rr->next)
		{
		while (rr->NextUpdateCredit && m->timenow - rr->NextUpdateCredit >= 0) GrantUpdateCredit(rr);
		if (TimeToAnnounceThisRecord(rr, m->timenow))
			{
			if (rr->resrec.RecordType == kDNSRecordTypeDeregistering)
				{
				if (!rr->WakeUp.HMAC.l[0])
					{
					if (rr->AnnounceCount) rr->ImmedAnswer = mDNSInterfaceMark;		// Send goodbye packet on all interfaces
					}
				else
					{
					LogSPS("SendResponses: Sending wakeup %2d for %.6a %s", rr->AnnounceCount-3, &rr->WakeUp.IMAC, ARDisplayString(m, rr));
					SendWakeup(m, rr->resrec.InterfaceID, &rr->WakeUp.IMAC, &rr->WakeUp.password);
					for (r2 = rr; r2; r2=r2->next)
						if (r2->AnnounceCount && r2->resrec.InterfaceID == rr->resrec.InterfaceID && mDNSSameEthAddress(&r2->WakeUp.IMAC, &rr->WakeUp.IMAC))
							{
							// For now we only want to send a single Unsolicited Neighbor Advertisement restoring the address to the original
							// owner, because these packets can cause some IPv6 stacks to falsely conclude that there's an address conflict.
							if (r2->AddressProxy.type == mDNSAddrType_IPv6 && r2->AnnounceCount == WakeupCount)
								{
								LogSPS("NDP Announcement %2d Releasing traffic for H-MAC %.6a I-MAC %.6a %s",
									r2->AnnounceCount-3, &r2->WakeUp.HMAC, &r2->WakeUp.IMAC, ARDisplayString(m,r2));
								SendNDP(m, NDP_Adv, NDP_Override, r2, &r2->AddressProxy.ip.v6, &r2->WakeUp.IMAC, &AllHosts_v6, &AllHosts_v6_Eth);
								}
							r2->LastAPTime = m->timenow;
							// After 15 wakeups without success (maybe host has left the network) send three goodbyes instead
							if (--r2->AnnounceCount <= GoodbyeCount) r2->WakeUp.HMAC = zeroEthAddr;
							}
					}
				}
			else if (ResourceRecordIsValidAnswer(rr))
				{
				if (rr->AddressProxy.type)
					{
					rr->AnnounceCount--;
					rr->ThisAPInterval *= 2;
					rr->LastAPTime = m->timenow;
					if (rr->AddressProxy.type == mDNSAddrType_IPv4)
						{
						LogSPS("ARP Announcement %2d Capturing traffic for H-MAC %.6a I-MAC %.6a %s",
							rr->AnnounceCount, &rr->WakeUp.HMAC, &rr->WakeUp.IMAC, ARDisplayString(m,rr));
						SendARP(m, 1, rr, &rr->AddressProxy.ip.v4, &zeroEthAddr, &rr->AddressProxy.ip.v4, &onesEthAddr);
						}
					else if (rr->AddressProxy.type == mDNSAddrType_IPv6)
						{
						LogSPS("NDP Announcement %2d Capturing traffic for H-MAC %.6a I-MAC %.6a %s",
							rr->AnnounceCount, &rr->WakeUp.HMAC, &rr->WakeUp.IMAC, ARDisplayString(m,rr));
						SendNDP(m, NDP_Adv, NDP_Override, rr, &rr->AddressProxy.ip.v6, mDNSNULL, &AllHosts_v6, &AllHosts_v6_Eth);
						}
					}
				else
					{
					rr->ImmedAnswer = mDNSInterfaceMark;		// Send on all interfaces
					if (maxExistingAnnounceInterval < rr->ThisAPInterval)
						maxExistingAnnounceInterval = rr->ThisAPInterval;
					if (rr->UpdateBlocked) rr->UpdateBlocked = 0;
					}
				}
			}
		}

	// Any interface-specific records we're going to send are marked as being sent on all appropriate interfaces (which is just one)
	// Eligible records that are more than half-way to their announcement time are accelerated
	for (rr = m->ResourceRecords; rr; rr=rr->next)
		if ((rr->resrec.InterfaceID && rr->ImmedAnswer) ||
			(rr->ThisAPInterval <= maxExistingAnnounceInterval &&
			TimeToAnnounceThisRecord(rr, m->timenow + rr->ThisAPInterval/2) &&
			!rr->AddressProxy.type && 					// Don't include ARP Annoucements when considering which records to accelerate
			ResourceRecordIsValidAnswer(rr)))
			rr->ImmedAnswer = mDNSInterfaceMark;		// Send on all interfaces

	// When sending SRV records (particularly when announcing a new service) automatically add related Address record(s) as additionals
	// Note: Currently all address records are interface-specific, so it's safe to set ImmedAdditional to their InterfaceID,
	// which will be non-null. If by some chance there is an address record that's not interface-specific (should never happen)
	// then all that means is that it won't get sent -- which would not be the end of the world.
	for (rr = m->ResourceRecords; rr; rr=rr->next)
		{
		if (rr->ImmedAnswer && rr->resrec.rrtype == kDNSType_SRV)
			for (r2=m->ResourceRecords; r2; r2=r2->next)				// Scan list of resource records
				if (RRTypeIsAddressType(r2->resrec.rrtype) &&			// For all address records (A/AAAA) ...
					ResourceRecordIsValidAnswer(r2) &&					// ... which are valid for answer ...
					rr->LastMCTime - r2->LastMCTime >= 0 &&				// ... which we have not sent recently ...
					rr->resrec.rdatahash == r2->resrec.namehash &&		// ... whose name is the name of the SRV target
					SameDomainName(&rr->resrec.rdata->u.srv.target, r2->resrec.name) &&
					(rr->ImmedAnswer == mDNSInterfaceMark || rr->ImmedAnswer == r2->resrec.InterfaceID))
					r2->ImmedAdditional = r2->resrec.InterfaceID;		// ... then mark this address record for sending too
		// We also make sure we send the DeviceInfo TXT record too, if necessary
		// We check for RecordType == kDNSRecordTypeShared because we don't want to tag the
		// DeviceInfo TXT record onto a goodbye packet (RecordType == kDNSRecordTypeDeregistering).
		if (rr->ImmedAnswer && rr->resrec.RecordType == kDNSRecordTypeShared && rr->resrec.rrtype == kDNSType_PTR)
			if (ResourceRecordIsValidAnswer(&m->DeviceInfo) && SameDomainLabel(rr->resrec.rdata->u.name.c, m->DeviceInfo.resrec.name->c))
				{
				if (!m->DeviceInfo.ImmedAnswer) m->DeviceInfo.ImmedAnswer = rr->ImmedAnswer;
				else                            m->DeviceInfo.ImmedAnswer = mDNSInterfaceMark;
				}
		}

	// If there's a record which is supposed to be unique that we're going to send, then make sure that we give
	// the whole RRSet as an atomic unit. That means that if we have any other records with the same name/type/class
	// then we need to mark them for sending too. Otherwise, if we set the kDNSClass_UniqueRRSet bit on a
	// record, then other RRSet members that have not been sent recently will get flushed out of client caches.
	// -- If a record is marked to be sent on a certain interface, make sure the whole set is marked to be sent on that interface
	// -- If any record is marked to be sent on all interfaces, make sure the whole set is marked to be sent on all interfaces
	for (rr = m->ResourceRecords; rr; rr=rr->next)
		if (rr->resrec.RecordType & kDNSRecordTypeUniqueMask)
			{
			if (rr->ImmedAnswer)			// If we're sending this as answer, see that its whole RRSet is similarly marked
				{
				for (r2 = m->ResourceRecords; r2; r2=r2->next)
					if (ResourceRecordIsValidAnswer(r2))
						if (r2->ImmedAnswer != mDNSInterfaceMark &&
							r2->ImmedAnswer != rr->ImmedAnswer && SameResourceRecordSignature(r2, rr))
							r2->ImmedAnswer = !r2->ImmedAnswer ? rr->ImmedAnswer : mDNSInterfaceMark;
				}
			else if (rr->ImmedAdditional)	// If we're sending this as additional, see that its whole RRSet is similarly marked
				{
				for (r2 = m->ResourceRecords; r2; r2=r2->next)
					if (ResourceRecordIsValidAnswer(r2))
						if (r2->ImmedAdditional != rr->ImmedAdditional && SameResourceRecordSignature(r2, rr))
							r2->ImmedAdditional = rr->ImmedAdditional;
				}
			}

	// Now set SendRNow state appropriately
	for (rr = m->ResourceRecords; rr; rr=rr->next)
		{
		if (rr->ImmedAnswer == mDNSInterfaceMark)		// Sending this record on all appropriate interfaces
			{
			rr->SendRNow = !intf ? mDNSNULL : (rr->resrec.InterfaceID) ? rr->resrec.InterfaceID : intf->InterfaceID;
			rr->ImmedAdditional = mDNSNULL;				// No need to send as additional if sending as answer
			rr->LastMCTime      = m->timenow;
			rr->LastMCInterface = rr->ImmedAnswer;
			// If we're announcing this record, and it's at least half-way to its ordained time, then consider this announcement done
			if (TimeToAnnounceThisRecord(rr, m->timenow + rr->ThisAPInterval/2))
				{
				rr->AnnounceCount--;
				if (rr->resrec.RecordType != kDNSRecordTypeDeregistering)
					rr->ThisAPInterval *= 2;
				rr->LastAPTime = m->timenow;
				debugf("Announcing %##s (%s) %d", rr->resrec.name->c, DNSTypeName(rr->resrec.rrtype), rr->AnnounceCount);
				}
			}
		else if (rr->ImmedAnswer)						// Else, just respond to a single query on single interface:
			{
			rr->SendRNow        = rr->ImmedAnswer;		// Just respond on that interface
			rr->ImmedAdditional = mDNSNULL;				// No need to send as additional too
			rr->LastMCTime      = m->timenow;
			rr->LastMCInterface = rr->ImmedAnswer;
			}
		SetNextAnnounceProbeTime(m, rr);
		//if (rr->SendRNow) LogMsg("%-15.4a %s", &rr->v4Requester, ARDisplayString(m, rr));
		}

	// ***
	// *** 2. Loop through interface list, sending records as appropriate
	// ***

	while (intf)
		{
		const int OwnerRecordSpace = (m->AnnounceOwner && intf->MAC.l[0]) ? DNSOpt_Header_Space + DNSOpt_Owner_Space(&m->PrimaryMAC, &intf->MAC) : 0;
		int numDereg    = 0;
		int numAnnounce = 0;
		int numAnswer   = 0;
		mDNSu8 *responseptr = m->omsg.data;
		mDNSu8 *newptr;
		InitializeDNSMessage(&m->omsg.h, zeroID, ResponseFlags);

		// First Pass. Look for:
		// 1. Deregistering records that need to send their goodbye packet
		// 2. Updated records that need to retract their old data
		// 3. Answers and announcements we need to send
		for (rr = m->ResourceRecords; rr; rr=rr->next)
			{

			// Skip this interface if the record InterfaceID is *Any and the record is not
			// appropriate for the interface type.
			if ((rr->SendRNow == intf->InterfaceID) &&
				((rr->resrec.InterfaceID == mDNSInterface_Any) && !mDNSPlatformValidRecordForInterface(rr, intf)))
				{
					LogInfo("SendResponses: Not sending %s, on %s", ARDisplayString(m, rr), InterfaceNameForID(m, rr->SendRNow));
					rr->SendRNow = GetNextActiveInterfaceID(intf);
				}
			else if (rr->SendRNow == intf->InterfaceID)
				{
				RData  *OldRData    = rr->resrec.rdata;
				mDNSu16 oldrdlength = rr->resrec.rdlength;
				mDNSu8 active = (mDNSu8)
					(rr->resrec.RecordType != kDNSRecordTypeDeregistering &&
					(m->SleepState != SleepState_Sleeping || intf->SPSAddr[0].type || intf->SPSAddr[1].type || intf->SPSAddr[2].type));
				newptr = mDNSNULL;
				if (rr->NewRData && active)
					{
					// See if we should send a courtesy "goodbye" for the old data before we replace it.
					if (ResourceRecordIsValidAnswer(rr) && rr->resrec.RecordType == kDNSRecordTypeShared && rr->RequireGoodbye)
						{
						newptr = PutRR_OS_TTL(responseptr, &m->omsg.h.numAnswers, &rr->resrec, 0);
						if (newptr) { responseptr = newptr; numDereg++; rr->RequireGoodbye = mDNSfalse; }
						else continue; // If this packet is already too full to hold the goodbye for this record, skip it for now and we'll retry later
						}
					SetNewRData(&rr->resrec, rr->NewRData, rr->newrdlength);
					}

				if (rr->resrec.RecordType & kDNSRecordTypeUniqueMask)
					rr->resrec.rrclass |= kDNSClass_UniqueRRSet;		// Temporarily set the cache flush bit so PutResourceRecord will set it
				newptr = PutRR_OS_TTL(responseptr, &m->omsg.h.numAnswers, &rr->resrec, active ? rr->resrec.rroriginalttl : 0);
				rr->resrec.rrclass &= ~kDNSClass_UniqueRRSet;			// Make sure to clear cache flush bit back to normal state
				if (newptr)
					{
					responseptr = newptr;
					rr->RequireGoodbye = active;
					if (rr->resrec.RecordType == kDNSRecordTypeDeregistering) numDereg++;
					else if (rr->LastAPTime == m->timenow) numAnnounce++; else numAnswer++;
					}

				if (rr->NewRData && active)
					SetNewRData(&rr->resrec, OldRData, oldrdlength);

				// The first time through (pktcount==0), if this record is verified unique
				// (i.e. typically A, AAAA, SRV, TXT and reverse-mapping PTR), set the flag to add an NSEC too.
				if (!pktcount && active && (rr->resrec.RecordType & kDNSRecordTypeActiveUniqueMask) && !rr->SendNSECNow)
					rr->SendNSECNow = mDNSInterfaceMark;

				if (newptr)		// If succeeded in sending, advance to next interface
					{
					// If sending on all interfaces, go to next interface; else we're finished now
					if (rr->ImmedAnswer == mDNSInterfaceMark && rr->resrec.InterfaceID == mDNSInterface_Any)
						rr->SendRNow = GetNextActiveInterfaceID(intf);
					else
						rr->SendRNow = mDNSNULL;
					}
				}
			}

		// Second Pass. Add additional records, if there's space.
		newptr = responseptr;
		for (rr = m->ResourceRecords; rr; rr=rr->next)
			if (rr->ImmedAdditional == intf->InterfaceID)
				if (ResourceRecordIsValidAnswer(rr))
					{
					// If we have at least one answer already in the packet, then plan to add additionals too
					mDNSBool SendAdditional = (m->omsg.h.numAnswers > 0);

					// If we're not planning to send any additionals, but this record is a unique one, then
					// make sure we haven't already sent any other members of its RRSet -- if we have, then they
					// will have had the cache flush bit set, so now we need to finish the job and send the rest.
					if (!SendAdditional && (rr->resrec.RecordType & kDNSRecordTypeUniqueMask))
						{
						const AuthRecord *a;
						for (a = m->ResourceRecords; a; a=a->next)
							if (a->LastMCTime      == m->timenow &&
								a->LastMCInterface == intf->InterfaceID &&
								SameResourceRecordSignature(a, rr)) { SendAdditional = mDNStrue; break; }
						}
					if (!SendAdditional)					// If we don't want to send this after all,
						rr->ImmedAdditional = mDNSNULL;		// then cancel its ImmedAdditional field
					else if (newptr)						// Else, try to add it if we can
						{
						// The first time through (pktcount==0), if this record is verified unique
						// (i.e. typically A, AAAA, SRV, TXT and reverse-mapping PTR), set the flag to add an NSEC too.
						if (!pktcount && (rr->resrec.RecordType & kDNSRecordTypeActiveUniqueMask) && !rr->SendNSECNow)
							rr->SendNSECNow = mDNSInterfaceMark;

						if (rr->resrec.RecordType & kDNSRecordTypeUniqueMask)
							rr->resrec.rrclass |= kDNSClass_UniqueRRSet;	// Temporarily set the cache flush bit so PutResourceRecord will set it
						newptr = PutRR_OS(newptr, &m->omsg.h.numAdditionals, &rr->resrec);
						rr->resrec.rrclass &= ~kDNSClass_UniqueRRSet;		// Make sure to clear cache flush bit back to normal state
						if (newptr)
							{
							responseptr = newptr;
							rr->ImmedAdditional = mDNSNULL;
							rr->RequireGoodbye = mDNStrue;
							// If we successfully put this additional record in the packet, we record LastMCTime & LastMCInterface.
							// This matters particularly in the case where we have more than one IPv6 (or IPv4) address, because otherwise,
							// when we see our own multicast with the cache flush bit set, if we haven't set LastMCTime, then we'll get
							// all concerned and re-announce our record again to make sure it doesn't get flushed from peer caches.
							rr->LastMCTime      = m->timenow;
							rr->LastMCInterface = intf->InterfaceID;
							}
						}
					}

		// Third Pass. Add NSEC records, if there's space.
		// When we're generating an NSEC record in response to a specify query for that type
		// (recognized by rr->SendNSECNow == intf->InterfaceID) we should really put the NSEC in the Answer Section,
		// not Additional Section, but for now it's easier to handle both cases in this Additional Section loop here.
		for (rr = m->ResourceRecords; rr; rr=rr->next)
			if (rr->SendNSECNow == mDNSInterfaceMark || rr->SendNSECNow == intf->InterfaceID)
				{
				AuthRecord nsec;
				mDNS_SetupResourceRecord(&nsec, mDNSNULL, mDNSInterface_Any, kDNSType_NSEC, rr->resrec.rroriginalttl, kDNSRecordTypeUnique, AuthRecordAny, mDNSNULL, mDNSNULL);
				nsec.resrec.rrclass |= kDNSClass_UniqueRRSet;
				AssignDomainName(&nsec.namestorage, rr->resrec.name);
				mDNSPlatformMemZero(nsec.rdatastorage.u.nsec.bitmap, sizeof(nsec.rdatastorage.u.nsec.bitmap));
				for (r2 = m->ResourceRecords; r2; r2=r2->next)
					if (ResourceRecordIsValidAnswer(r2) && SameResourceRecordNameClassInterface(r2, rr))
						{
						if (r2->resrec.rrtype >= kDNSQType_ANY) { LogMsg("Can't create NSEC for record %s", ARDisplayString(m, r2)); break; }
						else nsec.rdatastorage.u.nsec.bitmap[r2->resrec.rrtype >> 3] |= 128 >> (r2->resrec.rrtype & 7);
						}
				newptr = responseptr;
				if (!r2)	// If we successfully built our NSEC record, add it to the packet now
					{
					newptr = PutRR_OS(responseptr, &m->omsg.h.numAdditionals, &nsec.resrec);
					if (newptr) responseptr = newptr;
					}

				// If we successfully put the NSEC record, clear the SendNSECNow flag
				// If we consider this NSEC optional, then we unconditionally clear the SendNSECNow flag, even if we fail to put this additional record
				if (newptr || rr->SendNSECNow == mDNSInterfaceMark)
					{
					rr->SendNSECNow = mDNSNULL;
					// Run through remainder of list clearing SendNSECNow flag for all other records which would generate the same NSEC
					for (r2 = rr->next; r2; r2=r2->next)
						if (SameResourceRecordNameClassInterface(r2, rr))
							if (r2->SendNSECNow == mDNSInterfaceMark || r2->SendNSECNow == intf->InterfaceID)
								r2->SendNSECNow = mDNSNULL;
					}
				}

		if (m->omsg.h.numAnswers || m->omsg.h.numAdditionals)
			{
			// If we have data to send, add OWNER option if necessary, then send packet

			if (OwnerRecordSpace)
				{
				AuthRecord opt;
				mDNS_SetupResourceRecord(&opt, mDNSNULL, mDNSInterface_Any, kDNSType_OPT, kStandardTTL, kDNSRecordTypeKnownUnique, AuthRecordAny, mDNSNULL, mDNSNULL);
				opt.resrec.rrclass    = NormalMaxDNSMessageData;
				opt.resrec.rdlength   = sizeof(rdataOPT);	// One option in this OPT record
				opt.resrec.rdestimate = sizeof(rdataOPT);
				SetupOwnerOpt(m, intf, &opt.resrec.rdata->u.opt[0]);
				newptr = PutResourceRecord(&m->omsg, responseptr, &m->omsg.h.numAdditionals, &opt.resrec);
				if (newptr) { responseptr = newptr; LogSPS("SendResponses put   %s", ARDisplayString(m, &opt)); }
				else if (m->omsg.h.numAnswers + m->omsg.h.numAuthorities + m->omsg.h.numAdditionals == 1)
					LogSPS("SendResponses: No space in packet for Owner OPT record (%d/%d/%d/%d) %s",
						m->omsg.h.numQuestions, m->omsg.h.numAnswers, m->omsg.h.numAuthorities, m->omsg.h.numAdditionals, ARDisplayString(m, &opt));
				else
					LogMsg("SendResponses: How did we fail to have space for Owner OPT record (%d/%d/%d/%d) %s",
						m->omsg.h.numQuestions, m->omsg.h.numAnswers, m->omsg.h.numAuthorities, m->omsg.h.numAdditionals, ARDisplayString(m, &opt));
				}

			debugf("SendResponses: Sending %d Deregistration%s, %d Announcement%s, %d Answer%s, %d Additional%s on %p",
				numDereg,                 numDereg                 == 1 ? "" : "s",
				numAnnounce,              numAnnounce              == 1 ? "" : "s",
				numAnswer,                numAnswer                == 1 ? "" : "s",
				m->omsg.h.numAdditionals, m->omsg.h.numAdditionals == 1 ? "" : "s", intf->InterfaceID);

			if (intf->IPv4Available) mDNSSendDNSMessage(m, &m->omsg, responseptr, intf->InterfaceID, mDNSNULL, &AllDNSLinkGroup_v4, MulticastDNSPort, mDNSNULL, mDNSNULL);
			if (intf->IPv6Available) mDNSSendDNSMessage(m, &m->omsg, responseptr, intf->InterfaceID, mDNSNULL, &AllDNSLinkGroup_v6, MulticastDNSPort, mDNSNULL, mDNSNULL);
			if (!m->SuppressSending) m->SuppressSending = NonZeroTime(m->timenow + (mDNSPlatformOneSecond+9)/10);
			if (++pktcount >= 1000) { LogMsg("SendResponses exceeded loop limit %d: giving up", pktcount); break; }
			// There might be more things to send on this interface, so go around one more time and try again.
			}
		else	// Nothing more to send on this interface; go to next
			{
			const NetworkInterfaceInfo *next = GetFirstActiveInterface(intf->next);
			#if MDNS_DEBUGMSGS && 0
			const char *const msg = next ? "SendResponses: Nothing more on %p; moving to %p" : "SendResponses: Nothing more on %p";
			debugf(msg, intf, next);
			#endif
			intf = next;
			pktcount = 0;		// When we move to a new interface, reset packet count back to zero -- NSEC generation logic uses it
			}
		}

	// ***
	// *** 3. Cleanup: Now that everything is sent, call client callback functions, and reset state variables
	// ***

	if (m->CurrentRecord)
		LogMsg("SendResponses ERROR m->CurrentRecord already set %s", ARDisplayString(m, m->CurrentRecord));
	m->CurrentRecord = m->ResourceRecords;
	while (m->CurrentRecord)
		{
		rr = m->CurrentRecord;
		m->CurrentRecord = rr->next;

		if (rr->SendRNow)
			{
			if (rr->ARType != AuthRecordLocalOnly && rr->ARType != AuthRecordP2P)
				LogMsg("SendResponses: No active interface %p to send: %p %02X %s", rr->SendRNow, rr->resrec.InterfaceID, rr->resrec.RecordType, ARDisplayString(m, rr));
			rr->SendRNow = mDNSNULL;
			}

		if (rr->ImmedAnswer || rr->resrec.RecordType == kDNSRecordTypeDeregistering)
			{
			if (rr->NewRData) CompleteRDataUpdate(m, rr);	// Update our rdata, clear the NewRData pointer, and return memory to the client

			if (rr->resrec.RecordType == kDNSRecordTypeDeregistering && rr->AnnounceCount == 0)
				{
				// For Unicast, when we get the response from the server, we will call CompleteDeregistration
				if (!AuthRecord_uDNS(rr)) CompleteDeregistration(m, rr);		// Don't touch rr after this
				}
			else
				{
				rr->ImmedAnswer  = mDNSNULL;
				rr->ImmedUnicast = mDNSfalse;
				rr->v4Requester  = zerov4Addr;
				rr->v6Requester  = zerov6Addr;
				}
			}
		}
	verbosedebugf("SendResponses: Next in %ld ticks", m->NextScheduledResponse - m->timenow);
	}

// Calling CheckCacheExpiration() is an expensive operation because it has to look at the entire cache,
// so we want to be lazy about how frequently we do it.
// 1. If a cache record is currently referenced by *no* active questions,
//    then we don't mind expiring it up to a minute late (who will know?)
// 2. Else, if a cache record is due for some of its final expiration queries,
//    we'll allow them to be late by up to 2% of the TTL
// 3. Else, if a cache record has completed all its final expiration queries without success,
//    and is expiring, and had an original TTL more than ten seconds, we'll allow it to be one second late
// 4. Else, it is expiring and had an original TTL of ten seconds or less (includes explicit goodbye packets),
//    so allow at most 1/10 second lateness
// 5. For records with rroriginalttl set to zero, that means we really want to delete them immediately
//    (we have a new record with DelayDelivery set, waiting for the old record to go away before we can notify clients).
#define CacheCheckGracePeriod(RR) (                                                   \
	((RR)->CRActiveQuestion == mDNSNULL            ) ? (60 * mDNSPlatformOneSecond) : \
	((RR)->UnansweredQueries < MaxUnansweredQueries) ? (TicksTTL(rr)/50)            : \
	((RR)->resrec.rroriginalttl > 10               ) ? (mDNSPlatformOneSecond)      : \
	((RR)->resrec.rroriginalttl > 0                ) ? (mDNSPlatformOneSecond/10)   : 0)

#define NextCacheCheckEvent(RR) ((RR)->NextRequiredQuery + CacheCheckGracePeriod(RR))

mDNSexport void ScheduleNextCacheCheckTime(mDNS *const m, const mDNSu32 slot, const mDNSs32 event)
	{
	if (m->rrcache_nextcheck[slot] - event > 0)
		m->rrcache_nextcheck[slot] = event;
	if (m->NextCacheCheck          - event > 0)
		m->NextCacheCheck          = event;
	}

// Note: MUST call SetNextCacheCheckTimeForRecord any time we change:
// rr->TimeRcvd
// rr->resrec.rroriginalttl
// rr->UnansweredQueries
// rr->CRActiveQuestion
mDNSlocal void SetNextCacheCheckTimeForRecord(mDNS *const m, CacheRecord *const rr)
	{
	rr->NextRequiredQuery = RRExpireTime(rr);

	// If we have an active question, then see if we want to schedule a refresher query for this record.
	// Usually we expect to do four queries, at 80-82%, 85-87%, 90-92% and then 95-97% of the TTL.
	if (rr->CRActiveQuestion && rr->UnansweredQueries < MaxUnansweredQueries)
		{
		rr->NextRequiredQuery -= TicksTTL(rr)/20 * (MaxUnansweredQueries - rr->UnansweredQueries);
		rr->NextRequiredQuery += mDNSRandom((mDNSu32)TicksTTL(rr)/50);
		verbosedebugf("SetNextCacheCheckTimeForRecord: NextRequiredQuery in %ld sec CacheCheckGracePeriod %d ticks for %s",
			(rr->NextRequiredQuery - m->timenow) / mDNSPlatformOneSecond, CacheCheckGracePeriod(rr), CRDisplayString(m,rr));
		}

	ScheduleNextCacheCheckTime(m, HashSlot(rr->resrec.name), NextCacheCheckEvent(rr));
	}

#define kMinimumReconfirmTime                     ((mDNSu32)mDNSPlatformOneSecond *  5)
#define kDefaultReconfirmTimeForWake              ((mDNSu32)mDNSPlatformOneSecond *  5)
#define kDefaultReconfirmTimeForNoAnswer          ((mDNSu32)mDNSPlatformOneSecond *  5)
#define kDefaultReconfirmTimeForFlappingInterface ((mDNSu32)mDNSPlatformOneSecond * 30)

mDNSlocal mStatus mDNS_Reconfirm_internal(mDNS *const m, CacheRecord *const rr, mDNSu32 interval)
	{
	if (interval < kMinimumReconfirmTime)
		interval = kMinimumReconfirmTime;
	if (interval > 0x10000000)	// Make sure interval doesn't overflow when we multiply by four below
		interval = 0x10000000;

	// If the expected expiration time for this record is more than interval+33%, then accelerate its expiration
	if (RRExpireTime(rr) - m->timenow > (mDNSs32)((interval * 4) / 3))
		{
		// Add a 33% random amount to the interval, to avoid synchronization between multiple hosts
		// For all the reconfirmations in a given batch, we want to use the same random value
		// so that the reconfirmation questions can be grouped into a single query packet
		if (!m->RandomReconfirmDelay) m->RandomReconfirmDelay = 1 + mDNSRandom(0x3FFFFFFF);
		interval += m->RandomReconfirmDelay % ((interval/3) + 1);
		rr->TimeRcvd          = m->timenow - (mDNSs32)interval * 3;
		rr->resrec.rroriginalttl     = (interval * 4 + mDNSPlatformOneSecond - 1) / mDNSPlatformOneSecond;
		SetNextCacheCheckTimeForRecord(m, rr);
		}
	debugf("mDNS_Reconfirm_internal:%6ld ticks to go for %s %p",
		RRExpireTime(rr) - m->timenow, CRDisplayString(m, rr), rr->CRActiveQuestion);
	return(mStatus_NoError);
	}

#define MaxQuestionInterval         (3600 * mDNSPlatformOneSecond)

// BuildQuestion puts a question into a DNS Query packet and if successful, updates the value of queryptr.
// It also appends to the list of known answer records that need to be included,
// and updates the forcast for the size of the known answer section.
mDNSlocal mDNSBool BuildQuestion(mDNS *const m, DNSMessage *query, mDNSu8 **queryptr, DNSQuestion *q,
	CacheRecord ***kalistptrptr, mDNSu32 *answerforecast)
	{
	mDNSBool ucast = (q->LargeAnswers || q->RequestUnicast) && m->CanReceiveUnicastOn5353;
	mDNSu16 ucbit = (mDNSu16)(ucast ? kDNSQClass_UnicastResponse : 0);
	const mDNSu8 *const limit = query->data + NormalMaxDNSMessageData;
	mDNSu8 *newptr = putQuestion(query, *queryptr, limit - *answerforecast, &q->qname, q->qtype, (mDNSu16)(q->qclass | ucbit));
	if (!newptr)
		{
		debugf("BuildQuestion: No more space in this packet for question %##s (%s)", q->qname.c, DNSTypeName(q->qtype));
		return(mDNSfalse);
		}
	else
		{
		mDNSu32 forecast = *answerforecast;
		const mDNSu32 slot = HashSlot(&q->qname);
		const CacheGroup *const cg = CacheGroupForName(m, slot, q->qnamehash, &q->qname);
		CacheRecord *rr;
		CacheRecord **ka = *kalistptrptr;	// Make a working copy of the pointer we're going to update

		for (rr = cg ? cg->members : mDNSNULL; rr; rr=rr->next)				// If we have a resource record in our cache,
			if (rr->resrec.InterfaceID == q->SendQNow &&					// received on this interface
				!(rr->resrec.RecordType & kDNSRecordTypeUniqueMask) &&		// which is a shared (i.e. not unique) record type
				rr->NextInKAList == mDNSNULL && ka != &rr->NextInKAList &&	// which is not already in the known answer list
				rr->resrec.rdlength <= SmallRecordLimit &&					// which is small enough to sensibly fit in the packet
				SameNameRecordAnswersQuestion(&rr->resrec, q) &&			// which answers our question
				rr->TimeRcvd + TicksTTL(rr)/2 - m->timenow >				// and its half-way-to-expiry time is at least 1 second away
												mDNSPlatformOneSecond)		// (also ensures we never include goodbye records with TTL=1)
				{
				// We don't want to include unique records in the Known Answer section. The Known Answer section
				// is intended to suppress floods of shared-record replies from many other devices on the network.
				// That concept really does not apply to unique records, and indeed if we do send a query for
				// which we have a unique record already in our cache, then including that unique record as a
				// Known Answer, so as to suppress the only answer we were expecting to get, makes little sense.

				*ka = rr;	// Link this record into our known answer chain
				ka = &rr->NextInKAList;
				// We forecast: compressed name (2) type (2) class (2) TTL (4) rdlength (2) rdata (n)
				forecast += 12 + rr->resrec.rdestimate;
				// If we're trying to put more than one question in this packet, and it doesn't fit
				// then undo that last question and try again next time
				if (query->h.numQuestions > 1 && newptr + forecast >= limit)
					{
					debugf("BuildQuestion: Retracting question %##s (%s) new forecast total %d",
						q->qname.c, DNSTypeName(q->qtype), newptr + forecast - query->data);
					query->h.numQuestions--;
					ka = *kalistptrptr;		// Go back to where we started and retract these answer records
					while (*ka) { CacheRecord *c = *ka; *ka = mDNSNULL; ka = &c->NextInKAList; }
					return(mDNSfalse);		// Return false, so we'll try again in the next packet
					}
				}

		// Success! Update our state pointers, increment UnansweredQueries as appropriate, and return
		*queryptr        = newptr;				// Update the packet pointer
		*answerforecast  = forecast;			// Update the forecast
		*kalistptrptr    = ka;					// Update the known answer list pointer
		if (ucast) q->ExpectUnicastResp = NonZeroTime(m->timenow);

		for (rr = cg ? cg->members : mDNSNULL; rr; rr=rr->next)				// For every resource record in our cache,
			if (rr->resrec.InterfaceID == q->SendQNow &&					// received on this interface
				rr->NextInKAList == mDNSNULL && ka != &rr->NextInKAList &&	// which is not in the known answer list
				SameNameRecordAnswersQuestion(&rr->resrec, q))				// which answers our question
					{
					rr->UnansweredQueries++;								// indicate that we're expecting a response
					rr->LastUnansweredTime = m->timenow;
					SetNextCacheCheckTimeForRecord(m, rr);
					}

		return(mDNStrue);
		}
	}

// When we have a query looking for a specified name, but there appear to be no answers with
// that name, ReconfirmAntecedents() is called with depth=0 to start the reconfirmation process
// for any records in our cache that reference the given name (e.g. PTR and SRV records).
// For any such cache record we find, we also recursively call ReconfirmAntecedents() for *its* name.
// We increment depth each time we recurse, to guard against possible infinite loops, with a limit of 5.
// A typical reconfirmation scenario might go like this:
// Depth 0: Name "myhost.local" has no address records
// Depth 1: SRV "My Service._example._tcp.local." refers to "myhost.local"; may be stale
// Depth 2: PTR "_example._tcp.local." refers to "My Service"; may be stale
// Depth 3: PTR "_services._dns-sd._udp.local." refers to "_example._tcp.local."; may be stale
// Currently depths 4 and 5 are not expected to occur; if we did get to depth 5 we'd reconfim any records we
// found referring to the given name, but not recursively descend any further reconfirm *their* antecedents.
mDNSlocal void ReconfirmAntecedents(mDNS *const m, const domainname *const name, const mDNSu32 namehash, const int depth)
	{
	mDNSu32 slot;
	CacheGroup *cg;
	CacheRecord *cr;
	debugf("ReconfirmAntecedents (depth=%d) for %##s", depth, name->c);
	FORALL_CACHERECORDS(slot, cg, cr)
		{
		domainname *crtarget = GetRRDomainNameTarget(&cr->resrec);
		if (crtarget && cr->resrec.rdatahash == namehash && SameDomainName(crtarget, name))
			{
			LogInfo("ReconfirmAntecedents: Reconfirming (depth=%d) %s", depth, CRDisplayString(m, cr));
			mDNS_Reconfirm_internal(m, cr, kDefaultReconfirmTimeForNoAnswer);
			if (depth < 5) ReconfirmAntecedents(m, cr->resrec.name, cr->resrec.namehash, depth+1);
			}
		}
	}

// If we get no answer for a AAAA query, then before doing an automatic implicit ReconfirmAntecedents
// we check if we have an address record for the same name. If we do have an IPv4 address for a given
// name but not an IPv6 address, that's okay (it just means the device doesn't do IPv6) so the failure
// to get a AAAA response is not grounds to doubt the PTR/SRV chain that lead us to that name.
mDNSlocal const CacheRecord *CacheHasAddressTypeForName(mDNS *const m, const domainname *const name, const mDNSu32 namehash)
	{
	CacheGroup *const cg = CacheGroupForName(m, HashSlot(name), namehash, name);
	const CacheRecord *cr = cg ? cg->members : mDNSNULL;
	while (cr && !RRTypeIsAddressType(cr->resrec.rrtype)) cr=cr->next;
	return(cr);
	}

mDNSlocal const CacheRecord *FindSPSInCache1(mDNS *const m, const DNSQuestion *const q, const CacheRecord *const c0, const CacheRecord *const c1)
	{
	CacheGroup *const cg = CacheGroupForName(m, HashSlot(&q->qname), q->qnamehash, &q->qname);
	const CacheRecord *cr, *bestcr = mDNSNULL;
	mDNSu32 bestmetric = 1000000;
	for (cr = cg ? cg->members : mDNSNULL; cr; cr=cr->next)
		if (cr->resrec.rrtype == kDNSType_PTR && cr->resrec.rdlength >= 6)						// If record is PTR type, with long enough name,
			if (cr != c0 && cr != c1)															// that's not one we've seen before,
				if (SameNameRecordAnswersQuestion(&cr->resrec, q))								// and answers our browse query,
					if (!IdenticalSameNameRecord(&cr->resrec, &m->SPSRecords.RR_PTR.resrec))	// and is not our own advertised service...
						{
						mDNSu32 metric = SPSMetric(cr->resrec.rdata->u.name.c);
						if (bestmetric > metric) { bestmetric = metric; bestcr = cr; }
						}
	return(bestcr);
	}

// Finds the three best Sleep Proxies we currently have in our cache
mDNSexport void FindSPSInCache(mDNS *const m, const DNSQuestion *const q, const CacheRecord *sps[3])
	{
	sps[0] =                      FindSPSInCache1(m, q, mDNSNULL, mDNSNULL);
	sps[1] = !sps[0] ? mDNSNULL : FindSPSInCache1(m, q, sps[0],   mDNSNULL);
	sps[2] = !sps[1] ? mDNSNULL : FindSPSInCache1(m, q, sps[0],   sps[1]);
	}

// Only DupSuppressInfos newer than the specified 'time' are allowed to remain active
mDNSlocal void ExpireDupSuppressInfo(DupSuppressInfo ds[DupSuppressInfoSize], mDNSs32 time)
	{
	int i;
	for (i=0; i<DupSuppressInfoSize; i++) if (ds[i].Time - time < 0) ds[i].InterfaceID = mDNSNULL;
	}

mDNSlocal void ExpireDupSuppressInfoOnInterface(DupSuppressInfo ds[DupSuppressInfoSize], mDNSs32 time, mDNSInterfaceID InterfaceID)
	{
	int i;
	for (i=0; i<DupSuppressInfoSize; i++) if (ds[i].InterfaceID == InterfaceID && ds[i].Time - time < 0) ds[i].InterfaceID = mDNSNULL;
	}

mDNSlocal mDNSBool SuppressOnThisInterface(const DupSuppressInfo ds[DupSuppressInfoSize], const NetworkInterfaceInfo * const intf)
	{
	int i;
	mDNSBool v4 = !intf->IPv4Available;		// If this interface doesn't do v4, we don't need to find a v4 duplicate of this query
	mDNSBool v6 = !intf->IPv6Available;		// If this interface doesn't do v6, we don't need to find a v6 duplicate of this query
	for (i=0; i<DupSuppressInfoSize; i++)
		if (ds[i].InterfaceID == intf->InterfaceID)
			{
			if      (ds[i].Type == mDNSAddrType_IPv4) v4 = mDNStrue;
			else if (ds[i].Type == mDNSAddrType_IPv6) v6 = mDNStrue;
			if (v4 && v6) return(mDNStrue);
			}
	return(mDNSfalse);
	}

mDNSlocal int RecordDupSuppressInfo(DupSuppressInfo ds[DupSuppressInfoSize], mDNSs32 Time, mDNSInterfaceID InterfaceID, mDNSs32 Type)
	{
	int i, j;

	// See if we have this one in our list somewhere already
	for (i=0; i<DupSuppressInfoSize; i++) if (ds[i].InterfaceID == InterfaceID && ds[i].Type == Type) break;

	// If not, find a slot we can re-use
	if (i >= DupSuppressInfoSize)
		{
		i = 0;
		for (j=1; j<DupSuppressInfoSize && ds[i].InterfaceID; j++)
			if (!ds[j].InterfaceID || ds[j].Time - ds[i].Time < 0)
				i = j;
		}

	// Record the info about this query we saw
	ds[i].Time        = Time;
	ds[i].InterfaceID = InterfaceID;
	ds[i].Type        = Type;

	return(i);
	}

mDNSlocal void mDNSSendWakeOnResolve(mDNS *const m, DNSQuestion *q)
	{
	int len, i, cnt;
	mDNSInterfaceID InterfaceID = q->InterfaceID;
	domainname *d = &q->qname;

	// We can't send magic packets without knowing which interface to send it on.
	if (InterfaceID == mDNSInterface_Any || InterfaceID == mDNSInterface_LocalOnly || InterfaceID == mDNSInterface_P2P)
		{
		LogMsg("mDNSSendWakeOnResolve: ERROR!! Invalid InterfaceID %p for question %##s", InterfaceID, q->qname.c);
		return;
		}

	// Split MAC@IPAddress and pass them separately
	len = d->c[0];
	i = 1;
	cnt = 0;
	for (i = 1; i < len; i++)
		{
		if (d->c[i] == '@')
			{
			char EthAddr[18];	// ethernet adddress : 12 bytes + 5 ":" + 1 NULL byte
			char IPAddr[47];    // Max IP address len: 46 bytes (IPv6) + 1 NULL byte
			if (cnt != 5)
				{
				LogMsg("mDNSSendWakeOnResolve: ERROR!! Malformed Ethernet address %##s, cnt %d", q->qname.c, cnt);
				return;
				}
			if ((i - 1) > (int) (sizeof(EthAddr) - 1))
				{
				LogMsg("mDNSSendWakeOnResolve: ERROR!! Malformed Ethernet address %##s, length %d", q->qname.c, i - 1);
				return;
				}
			if ((len - i) > (int)(sizeof(IPAddr) - 1))
				{
				LogMsg("mDNSSendWakeOnResolve: ERROR!! Malformed IP address %##s, length %d", q->qname.c, len - i);
				return;
				}
			mDNSPlatformMemCopy(EthAddr, &d->c[1], i - 1);
			EthAddr[i - 1] = 0;
			mDNSPlatformMemCopy(IPAddr, &d->c[i + 1], len - i);
			IPAddr[len - i] = 0;
			mDNSPlatformSendWakeupPacket(m, InterfaceID, EthAddr, IPAddr, InitialWakeOnResolveCount - q->WakeOnResolveCount);
			return;
			}
		else if (d->c[i] == ':')
			cnt++;
		}
	LogMsg("mDNSSendWakeOnResolve: ERROR!! Malformed WakeOnResolve name %##s", q->qname.c);
	}


mDNSlocal mDNSBool AccelerateThisQuery(mDNS *const m, DNSQuestion *q)
	{
	// If more than 90% of the way to the query time, we should unconditionally accelerate it
	if (TimeToSendThisQuestion(q, m->timenow + q->ThisQInterval/10))
		return(mDNStrue);

	// If half-way to next scheduled query time, only accelerate if it will add less than 512 bytes to the packet
	if (TimeToSendThisQuestion(q, m->timenow + q->ThisQInterval/2))
		{
		// We forecast: qname (n) type (2) class (2)
		mDNSu32 forecast = (mDNSu32)DomainNameLength(&q->qname) + 4;
		const mDNSu32 slot = HashSlot(&q->qname);
		const CacheGroup *const cg = CacheGroupForName(m, slot, q->qnamehash, &q->qname);
		const CacheRecord *rr;
		for (rr = cg ? cg->members : mDNSNULL; rr; rr=rr->next)				// If we have a resource record in our cache,
			if (rr->resrec.rdlength <= SmallRecordLimit &&					// which is small enough to sensibly fit in the packet
				SameNameRecordAnswersQuestion(&rr->resrec, q) &&			// which answers our question
				rr->TimeRcvd + TicksTTL(rr)/2 - m->timenow >= 0 &&			// and it is less than half-way to expiry
				rr->NextRequiredQuery - (m->timenow + q->ThisQInterval) > 0)// and we'll ask at least once again before NextRequiredQuery
				{
				// We forecast: compressed name (2) type (2) class (2) TTL (4) rdlength (2) rdata (n)
				forecast += 12 + rr->resrec.rdestimate;
				if (forecast >= 512) return(mDNSfalse);	// If this would add 512 bytes or more to the packet, don't accelerate
				}
		return(mDNStrue);
		}

	return(mDNSfalse);
	}

// How Standard Queries are generated:
// 1. The Question Section contains the question
// 2. The Additional Section contains answers we already know, to suppress duplicate responses

// How Probe Queries are generated:
// 1. The Question Section contains queries for the name we intend to use, with QType=ANY because
// if some other host is already using *any* records with this name, we want to know about it.
// 2. The Authority Section contains the proposed values we intend to use for one or more
// of our records with that name (analogous to the Update section of DNS Update packets)
// because if some other host is probing at the same time, we each want to know what the other is
// planning, in order to apply the tie-breaking rule to see who gets to use the name and who doesn't.

mDNSlocal void SendQueries(mDNS *const m)
	{
	mDNSu32 slot;
	CacheGroup *cg;
	CacheRecord *cr;
	AuthRecord *ar;
	int pktcount = 0;
	DNSQuestion *q;
	// For explanation of maxExistingQuestionInterval logic, see comments for maxExistingAnnounceInterval
	mDNSs32 maxExistingQuestionInterval = 0;
	const NetworkInterfaceInfo *intf = GetFirstActiveInterface(m->HostInterfaces);
	CacheRecord *KnownAnswerList = mDNSNULL;

	// 1. If time for a query, work out what we need to do

	// We're expecting to send a query anyway, so see if any expiring cache records are close enough
	// to their NextRequiredQuery to be worth batching them together with this one
	FORALL_CACHERECORDS(slot, cg, cr)
		if (cr->CRActiveQuestion && cr->UnansweredQueries < MaxUnansweredQueries)
			if (m->timenow + TicksTTL(cr)/50 - cr->NextRequiredQuery >= 0)
				{
				debugf("Sending %d%% cache expiration query for %s", 80 + 5 * cr->UnansweredQueries, CRDisplayString(m, cr));
				q = cr->CRActiveQuestion;
				ExpireDupSuppressInfoOnInterface(q->DupSuppress, m->timenow - TicksTTL(cr)/20, cr->resrec.InterfaceID);
				// For uDNS queries (TargetQID non-zero) we adjust LastQTime,
				// and bump UnansweredQueries so that we don't spin trying to send the same cache expiration query repeatedly
				if      (q->Target.type)                        q->SendQNow = mDNSInterfaceMark;	// If targeted query, mark it
				else if (!mDNSOpaque16IsZero(q->TargetQID))     { q->LastQTime = m->timenow - q->ThisQInterval; cr->UnansweredQueries++; }
				else if (q->SendQNow == mDNSNULL)               q->SendQNow = cr->resrec.InterfaceID;
				else if (q->SendQNow != cr->resrec.InterfaceID) q->SendQNow = mDNSInterfaceMark;
				}

	// Scan our list of questions to see which:
	//     *WideArea*  queries need to be sent
	//     *unicast*   queries need to be sent
	//     *multicast* queries we're definitely going to send
	if (m->CurrentQuestion)
		LogMsg("SendQueries ERROR m->CurrentQuestion already set: %##s (%s)", m->CurrentQuestion->qname.c, DNSTypeName(m->CurrentQuestion->qtype));
	m->CurrentQuestion = m->Questions;
	while (m->CurrentQuestion && m->CurrentQuestion != m->NewQuestions)
		{
		q = m->CurrentQuestion;
		if (q->Target.type && (q->SendQNow || TimeToSendThisQuestion(q, m->timenow)))
			{
			mDNSu8       *qptr        = m->omsg.data;
			const mDNSu8 *const limit = m->omsg.data + sizeof(m->omsg.data);

			// If we fail to get a new on-demand socket (should only happen cases of the most extreme resource exhaustion), we'll try again next time
			if (!q->LocalSocket) q->LocalSocket = mDNSPlatformUDPSocket(m, zeroIPPort);
			if (q->LocalSocket)
				{
				InitializeDNSMessage(&m->omsg.h, q->TargetQID, QueryFlags);
				qptr = putQuestion(&m->omsg, qptr, limit, &q->qname, q->qtype, q->qclass);
				mDNSSendDNSMessage(m, &m->omsg, qptr, mDNSInterface_Any, q->LocalSocket, &q->Target, q->TargetPort, mDNSNULL, mDNSNULL);
				q->ThisQInterval    *= QuestionIntervalStep;
				}
			if (q->ThisQInterval > MaxQuestionInterval)
				q->ThisQInterval = MaxQuestionInterval;
			q->LastQTime         = m->timenow;
			q->LastQTxTime       = m->timenow;
			q->RecentAnswerPkts  = 0;
			q->SendQNow          = mDNSNULL;
			q->ExpectUnicastResp = NonZeroTime(m->timenow);
			}
		else if (mDNSOpaque16IsZero(q->TargetQID) && !q->Target.type && TimeToSendThisQuestion(q, m->timenow))
			{
			//LogInfo("Time to send %##s (%s) %d", q->qname.c, DNSTypeName(q->qtype), m->timenow - NextQSendTime(q));
			q->SendQNow = mDNSInterfaceMark;		// Mark this question for sending on all interfaces
			if (maxExistingQuestionInterval < q->ThisQInterval)
				maxExistingQuestionInterval = q->ThisQInterval;
			}
		// If m->CurrentQuestion wasn't modified out from under us, advance it now
		// We can't do this at the start of the loop because uDNS_CheckCurrentQuestion() depends on having
		// m->CurrentQuestion point to the right question
		if (q == m->CurrentQuestion) m->CurrentQuestion = m->CurrentQuestion->next;
		}
	while (m->CurrentQuestion)
		{
		LogInfo("SendQueries question loop 1: Skipping NewQuestion %##s (%s)", m->CurrentQuestion->qname.c, DNSTypeName(m->CurrentQuestion->qtype));
		m->CurrentQuestion = m->CurrentQuestion->next;
		}
	m->CurrentQuestion = mDNSNULL;

	// Scan our list of questions
	// (a) to see if there are any more that are worth accelerating, and
	// (b) to update the state variables for *all* the questions we're going to send
	// Note: Don't set NextScheduledQuery until here, because uDNS_CheckCurrentQuestion in the loop above can add new questions to the list,
	// which causes NextScheduledQuery to get (incorrectly) set to m->timenow. Setting it here is the right place, because the very
	// next thing we do is scan the list and call SetNextQueryTime() for every question we find, so we know we end up with the right value.
	m->NextScheduledQuery = m->timenow + 0x78000000;
	for (q = m->Questions; q && q != m->NewQuestions; q=q->next)
		{
		if (mDNSOpaque16IsZero(q->TargetQID) && (q->SendQNow ||
			(!q->Target.type && ActiveQuestion(q) && q->ThisQInterval <= maxExistingQuestionInterval && AccelerateThisQuery(m,q))))
			{
			// If at least halfway to next query time, advance to next interval
			// If less than halfway to next query time, then
			// treat this as logically a repeat of the last transmission, without advancing the interval
			if (m->timenow - (q->LastQTime + (q->ThisQInterval/2)) >= 0)
				{
				//LogInfo("Accelerating %##s (%s) %d", q->qname.c, DNSTypeName(q->qtype), m->timenow - NextQSendTime(q));
				q->SendQNow = mDNSInterfaceMark;	// Mark this question for sending on all interfaces
				debugf("SendQueries: %##s (%s) next interval %d seconds RequestUnicast = %d",
					q->qname.c, DNSTypeName(q->qtype), q->ThisQInterval / InitialQuestionInterval, q->RequestUnicast);
				q->ThisQInterval *= QuestionIntervalStep;
				if (q->ThisQInterval > MaxQuestionInterval)
					q->ThisQInterval = MaxQuestionInterval;
				else if (q->CurrentAnswers == 0 && q->ThisQInterval == InitialQuestionInterval * QuestionIntervalStep3 && !q->RequestUnicast &&
						!(RRTypeIsAddressType(q->qtype) && CacheHasAddressTypeForName(m, &q->qname, q->qnamehash)))
					{
					// Generally don't need to log this.
					// It's not especially noteworthy if a query finds no results -- this usually happens for domain
					// enumeration queries in the LL subdomain (e.g. "db._dns-sd._udp.0.0.254.169.in-addr.arpa")
					// and when there simply happen to be no instances of the service the client is looking
					// for (e.g. iTunes is set to look for RAOP devices, and the current network has none).
					debugf("SendQueries: Zero current answers for %##s (%s); will reconfirm antecedents",
						q->qname.c, DNSTypeName(q->qtype));
					// Sending third query, and no answers yet; time to begin doubting the source
					ReconfirmAntecedents(m, &q->qname, q->qnamehash, 0);
					}
				}

			// Mark for sending. (If no active interfaces, then don't even try.)
			q->SendOnAll = (q->SendQNow == mDNSInterfaceMark);
			if (q->SendOnAll)
				{
				q->SendQNow  = !intf ? mDNSNULL : (q->InterfaceID) ? q->InterfaceID : intf->InterfaceID;
				q->LastQTime = m->timenow;
				}

			// If we recorded a duplicate suppression for this question less than half an interval ago,
			// then we consider it recent enough that we don't need to do an identical query ourselves.
			ExpireDupSuppressInfo(q->DupSuppress, m->timenow - q->ThisQInterval/2);

			q->LastQTxTime      = m->timenow;
			q->RecentAnswerPkts = 0;
			if (q->RequestUnicast) q->RequestUnicast--;
			}
		// For all questions (not just the ones we're sending) check what the next scheduled event will be
		// We don't need to consider NewQuestions here because for those we'll set m->NextScheduledQuery in AnswerNewQuestion
		SetNextQueryTime(m,q);
		}

	// 2. Scan our authoritative RR list to see what probes we might need to send

	m->NextScheduledProbe = m->timenow + 0x78000000;

	if (m->CurrentRecord)
		LogMsg("SendQueries ERROR m->CurrentRecord already set %s", ARDisplayString(m, m->CurrentRecord));
	m->CurrentRecord = m->ResourceRecords;
	while (m->CurrentRecord)
		{
		ar = m->CurrentRecord;
		m->CurrentRecord = ar->next;
		if (!AuthRecord_uDNS(ar) && ar->resrec.RecordType == kDNSRecordTypeUnique)	// For all records that are still probing...
			{
			// 1. If it's not reached its probe time, just make sure we update m->NextScheduledProbe correctly
			if (m->timenow - (ar->LastAPTime + ar->ThisAPInterval) < 0)
				{
				SetNextAnnounceProbeTime(m, ar);
				}
			// 2. else, if it has reached its probe time, mark it for sending and then update m->NextScheduledProbe correctly
			else if (ar->ProbeCount)
				{
				if (ar->AddressProxy.type == mDNSAddrType_IPv4)
					{
					LogSPS("SendQueries ARP Probe %d %s %s", ar->ProbeCount, InterfaceNameForID(m, ar->resrec.InterfaceID), ARDisplayString(m,ar));
					SendARP(m, 1, ar, &zerov4Addr, &zeroEthAddr, &ar->AddressProxy.ip.v4, &ar->WakeUp.IMAC);
					}
				else if (ar->AddressProxy.type == mDNSAddrType_IPv6)
					{
					LogSPS("SendQueries NDP Probe %d %s %s", ar->ProbeCount, InterfaceNameForID(m, ar->resrec.InterfaceID), ARDisplayString(m,ar));
					// IPv6 source = zero
					// No target hardware address
					// IPv6 target address is address we're probing
					// Ethernet destination address is Ethernet interface address of the Sleep Proxy client we're probing
					SendNDP(m, NDP_Sol, 0, ar, &zerov6Addr, mDNSNULL, &ar->AddressProxy.ip.v6, &ar->WakeUp.IMAC);
					}
				// Mark for sending. (If no active interfaces, then don't even try.)
				ar->SendRNow   = (!intf || ar->WakeUp.HMAC.l[0]) ? mDNSNULL : ar->resrec.InterfaceID ? ar->resrec.InterfaceID : intf->InterfaceID;
				ar->LastAPTime = m->timenow;
				// When we have a late conflict that resets a record to probing state we use a special marker value greater
				// than DefaultProbeCountForTypeUnique. Here we detect that state and reset ar->ProbeCount back to the right value.
				if (ar->ProbeCount > DefaultProbeCountForTypeUnique)
					ar->ProbeCount = DefaultProbeCountForTypeUnique;
				ar->ProbeCount--;
				SetNextAnnounceProbeTime(m, ar);
				if (ar->ProbeCount == 0)
					{
					// If this is the last probe for this record, then see if we have any matching records
					// on our duplicate list which should similarly have their ProbeCount cleared to zero...
					AuthRecord *r2;
					for (r2 = m->DuplicateRecords; r2; r2=r2->next)
						if (r2->resrec.RecordType == kDNSRecordTypeUnique && RecordIsLocalDuplicate(r2, ar))
							r2->ProbeCount = 0;
					// ... then acknowledge this record to the client.
					// We do this optimistically, just as we're about to send the third probe.
					// This helps clients that both advertise and browse, and want to filter themselves
					// from the browse results list, because it helps ensure that the registration
					// confirmation will be delivered 1/4 second *before* the browse "add" event.
					// A potential downside is that we could deliver a registration confirmation and then find out
					// moments later that there's a name conflict, but applications have to be prepared to handle
					// late conflicts anyway (e.g. on connection of network cable, etc.), so this is nothing new.
					if (!ar->Acknowledged) AcknowledgeRecord(m, ar);
					}
				}
			// else, if it has now finished probing, move it to state Verified,
			// and update m->NextScheduledResponse so it will be announced
			else
				{
				if (!ar->Acknowledged) AcknowledgeRecord(m, ar);	// Defensive, just in case it got missed somehow
				ar->resrec.RecordType     = kDNSRecordTypeVerified;
				ar->ThisAPInterval = DefaultAnnounceIntervalForTypeUnique;
				ar->LastAPTime     = m->timenow - DefaultAnnounceIntervalForTypeUnique;
				SetNextAnnounceProbeTime(m, ar);
				}
			}
		}
	m->CurrentRecord = m->DuplicateRecords;
	while (m->CurrentRecord)
		{
		ar = m->CurrentRecord;
		m->CurrentRecord = ar->next;
		if (ar->resrec.RecordType == kDNSRecordTypeUnique && ar->ProbeCount == 0 && !ar->Acknowledged)
			AcknowledgeRecord(m, ar);
		}

	// 3. Now we know which queries and probes we're sending,
	// go through our interface list sending the appropriate queries on each interface
	while (intf)
		{
		const int OwnerRecordSpace = (m->AnnounceOwner && intf->MAC.l[0]) ? DNSOpt_Header_Space + DNSOpt_Owner_Space(&m->PrimaryMAC, &intf->MAC) : 0;
		mDNSu8 *queryptr = m->omsg.data;
		InitializeDNSMessage(&m->omsg.h, zeroID, QueryFlags);
		if (KnownAnswerList) verbosedebugf("SendQueries:   KnownAnswerList set... Will continue from previous packet");
		if (!KnownAnswerList)
			{
			// Start a new known-answer list
			CacheRecord **kalistptr = &KnownAnswerList;
			mDNSu32 answerforecast = OwnerRecordSpace;		// We start by assuming we'll need at least enough space to put the Owner Option

			// Put query questions in this packet
			for (q = m->Questions; q && q != m->NewQuestions; q=q->next)
				{
				if (mDNSOpaque16IsZero(q->TargetQID) && (q->SendQNow == intf->InterfaceID))
					{
					debugf("SendQueries: %s question for %##s (%s) at %d forecast total %d",
						SuppressOnThisInterface(q->DupSuppress, intf) ? "Suppressing" : "Putting    ",
						q->qname.c, DNSTypeName(q->qtype), queryptr - m->omsg.data, queryptr + answerforecast - m->omsg.data);

					// If we're suppressing this question, or we successfully put it, update its SendQNow state
					if (SuppressOnThisInterface(q->DupSuppress, intf) ||
						BuildQuestion(m, &m->omsg, &queryptr, q, &kalistptr, &answerforecast))
						{
						q->SendQNow = (q->InterfaceID || !q->SendOnAll) ? mDNSNULL : GetNextActiveInterfaceID(intf);
						if (q->WakeOnResolveCount)
							{
							mDNSSendWakeOnResolve(m, q);
							q->WakeOnResolveCount--;
							}
						}
					}
				}

			// Put probe questions in this packet
			for (ar = m->ResourceRecords; ar; ar=ar->next)
				if (ar->SendRNow == intf->InterfaceID)
					{
					mDNSBool ucast = (ar->ProbeCount >= DefaultProbeCountForTypeUnique-1) && m->CanReceiveUnicastOn5353;
					mDNSu16 ucbit = (mDNSu16)(ucast ? kDNSQClass_UnicastResponse : 0);
					const mDNSu8 *const limit = m->omsg.data + (m->omsg.h.numQuestions ? NormalMaxDNSMessageData : AbsoluteMaxDNSMessageData);
					// We forecast: compressed name (2) type (2) class (2) TTL (4) rdlength (2) rdata (n)
					mDNSu32 forecast = answerforecast + 12 + ar->resrec.rdestimate;
					mDNSu8 *newptr = putQuestion(&m->omsg, queryptr, limit - forecast, ar->resrec.name, kDNSQType_ANY, (mDNSu16)(ar->resrec.rrclass | ucbit));
					if (newptr)
						{
						queryptr       = newptr;
						answerforecast = forecast;
						ar->SendRNow = (ar->resrec.InterfaceID) ? mDNSNULL : GetNextActiveInterfaceID(intf);
						ar->IncludeInProbe = mDNStrue;
						verbosedebugf("SendQueries:   Put Question %##s (%s) probecount %d",
							ar->resrec.name->c, DNSTypeName(ar->resrec.rrtype), ar->ProbeCount);
						}
					}
			}

		// Put our known answer list (either new one from this question or questions, or remainder of old one from last time)
		while (KnownAnswerList)
			{
			CacheRecord *ka = KnownAnswerList;
			mDNSu32 SecsSinceRcvd = ((mDNSu32)(m->timenow - ka->TimeRcvd)) / mDNSPlatformOneSecond;
			mDNSu8 *newptr = PutResourceRecordTTLWithLimit(&m->omsg, queryptr, &m->omsg.h.numAnswers,
				&ka->resrec, ka->resrec.rroriginalttl - SecsSinceRcvd, m->omsg.data + NormalMaxDNSMessageData - OwnerRecordSpace);
			if (newptr)
				{
				verbosedebugf("SendQueries:   Put %##s (%s) at %d - %d",
					ka->resrec.name->c, DNSTypeName(ka->resrec.rrtype), queryptr - m->omsg.data, newptr - m->omsg.data);
				queryptr = newptr;
				KnownAnswerList = ka->NextInKAList;
				ka->NextInKAList = mDNSNULL;
				}
			else
				{
				// If we ran out of space and we have more than one question in the packet, that's an error --
				// we shouldn't have put more than one question if there was a risk of us running out of space.
				if (m->omsg.h.numQuestions > 1)
					LogMsg("SendQueries:   Put %d answers; No more space for known answers", m->omsg.h.numAnswers);
				m->omsg.h.flags.b[0] |= kDNSFlag0_TC;
				break;
				}
			}

		for (ar = m->ResourceRecords; ar; ar=ar->next)
			if (ar->IncludeInProbe)
				{
				mDNSu8 *newptr = PutResourceRecord(&m->omsg, queryptr, &m->omsg.h.numAuthorities, &ar->resrec);
				ar->IncludeInProbe = mDNSfalse;
				if (newptr) queryptr = newptr;
				else LogMsg("SendQueries:   How did we fail to have space for the Update record %s", ARDisplayString(m,ar));
				}

		if (queryptr > m->omsg.data)
			{
			if (OwnerRecordSpace)
				{
				AuthRecord opt;
				mDNS_SetupResourceRecord(&opt, mDNSNULL, mDNSInterface_Any, kDNSType_OPT, kStandardTTL, kDNSRecordTypeKnownUnique, AuthRecordAny, mDNSNULL, mDNSNULL);
				opt.resrec.rrclass    = NormalMaxDNSMessageData;
				opt.resrec.rdlength   = sizeof(rdataOPT);	// One option in this OPT record
				opt.resrec.rdestimate = sizeof(rdataOPT);
				SetupOwnerOpt(m, intf, &opt.resrec.rdata->u.opt[0]);
				LogSPS("SendQueries putting %s", ARDisplayString(m, &opt));
				queryptr = PutResourceRecordTTLWithLimit(&m->omsg, queryptr, &m->omsg.h.numAdditionals,
					&opt.resrec, opt.resrec.rroriginalttl, m->omsg.data + AbsoluteMaxDNSMessageData);
				if (!queryptr)
					LogMsg("SendQueries: How did we fail to have space for the OPT record (%d/%d/%d/%d) %s",
						m->omsg.h.numQuestions, m->omsg.h.numAnswers, m->omsg.h.numAuthorities, m->omsg.h.numAdditionals, ARDisplayString(m, &opt));
				if (queryptr > m->omsg.data + NormalMaxDNSMessageData)
					if (m->omsg.h.numQuestions != 1 || m->omsg.h.numAnswers != 0 || m->omsg.h.numAuthorities != 1 || m->omsg.h.numAdditionals != 1)
						LogMsg("SendQueries: Why did we generate oversized packet with OPT record %p %p %p (%d/%d/%d/%d) %s",
							m->omsg.data, m->omsg.data + NormalMaxDNSMessageData, queryptr,
							m->omsg.h.numQuestions, m->omsg.h.numAnswers, m->omsg.h.numAuthorities, m->omsg.h.numAdditionals, ARDisplayString(m, &opt));
				}

			if ((m->omsg.h.flags.b[0] & kDNSFlag0_TC) && m->omsg.h.numQuestions > 1)
				LogMsg("SendQueries: Should not have more than one question (%d) in a truncated packet", m->omsg.h.numQuestions);
			debugf("SendQueries:   Sending %d Question%s %d Answer%s %d Update%s on %p",
				m->omsg.h.numQuestions,   m->omsg.h.numQuestions   == 1 ? "" : "s",
				m->omsg.h.numAnswers,     m->omsg.h.numAnswers     == 1 ? "" : "s",
				m->omsg.h.numAuthorities, m->omsg.h.numAuthorities == 1 ? "" : "s", intf->InterfaceID);
			if (intf->IPv4Available) mDNSSendDNSMessage(m, &m->omsg, queryptr, intf->InterfaceID, mDNSNULL, &AllDNSLinkGroup_v4, MulticastDNSPort, mDNSNULL, mDNSNULL);
			if (intf->IPv6Available) mDNSSendDNSMessage(m, &m->omsg, queryptr, intf->InterfaceID, mDNSNULL, &AllDNSLinkGroup_v6, MulticastDNSPort, mDNSNULL, mDNSNULL);
			if (!m->SuppressSending) m->SuppressSending = NonZeroTime(m->timenow + (mDNSPlatformOneSecond+9)/10);
			if (++pktcount >= 1000)
				{ LogMsg("SendQueries exceeded loop limit %d: giving up", pktcount); break; }
			// There might be more records left in the known answer list, or more questions to send
			// on this interface, so go around one more time and try again.
			}
		else	// Nothing more to send on this interface; go to next
			{
			const NetworkInterfaceInfo *next = GetFirstActiveInterface(intf->next);
			#if MDNS_DEBUGMSGS && 0
			const char *const msg = next ? "SendQueries:   Nothing more on %p; moving to %p" : "SendQueries:   Nothing more on %p";
			debugf(msg, intf, next);
			#endif
			intf = next;
			}
		}

	// 4. Final housekeeping

	// 4a. Debugging check: Make sure we announced all our records
	for (ar = m->ResourceRecords; ar; ar=ar->next)
		if (ar->SendRNow)
			{
			if (ar->ARType != AuthRecordLocalOnly && ar->ARType != AuthRecordP2P)
				LogMsg("SendQueries: No active interface %p to send probe: %p %s", ar->SendRNow, ar->resrec.InterfaceID, ARDisplayString(m, ar));
			ar->SendRNow = mDNSNULL;
			}

	// 4b. When we have lingering cache records that we're keeping around for a few seconds in the hope
	// that their interface which went away might come back again, the logic will want to send queries
	// for those records, but we can't because their interface isn't here any more, so to keep the
	// state machine ticking over we just pretend we did so.
	// If the interface does not come back in time, the cache record will expire naturally
	FORALL_CACHERECORDS(slot, cg, cr)
		if (cr->CRActiveQuestion && cr->UnansweredQueries < MaxUnansweredQueries)
			if (m->timenow + TicksTTL(cr)/50 - cr->NextRequiredQuery >= 0)
				{
				cr->UnansweredQueries++;
				cr->CRActiveQuestion->SendQNow = mDNSNULL;
				SetNextCacheCheckTimeForRecord(m, cr);
				}

	// 4c. Debugging check: Make sure we sent all our planned questions
	// Do this AFTER the lingering cache records check above, because that will prevent spurious warnings for questions
	// we legitimately couldn't send because the interface is no longer available
	for (q = m->Questions; q; q=q->next)
		if (q->SendQNow)
			{
			DNSQuestion *x;
			for (x = m->NewQuestions; x; x=x->next) if (x == q) break;	// Check if this question is a NewQuestion
			LogMsg("SendQueries: No active interface %p to send %s question: %p %##s (%s)", q->SendQNow, x ? "new" : "old", q->InterfaceID, q->qname.c, DNSTypeName(q->qtype));
			q->SendQNow = mDNSNULL;
			}
	}

mDNSlocal void SendWakeup(mDNS *const m, mDNSInterfaceID InterfaceID, mDNSEthAddr *EthAddr, mDNSOpaque48 *password)
	{
	int i, j;
	mDNSu8 *ptr = m->omsg.data;
	NetworkInterfaceInfo *intf = FirstInterfaceForID(m, InterfaceID);
	if (!intf) { LogMsg("SendARP: No interface with InterfaceID %p found", InterfaceID); return; }

	// 0x00 Destination address
	for (i=0; i<6; i++) *ptr++ = EthAddr->b[i];

	// 0x06 Source address (Note: Since we don't currently set the BIOCSHDRCMPLT option, BPF will fill in the real interface address for us)
	for (i=0; i<6; i++) *ptr++ = intf->MAC.b[0];

	// 0x0C Ethertype (0x0842)
	*ptr++ = 0x08;
	*ptr++ = 0x42;

	// 0x0E Wakeup sync sequence
	for (i=0; i<6; i++) *ptr++ = 0xFF;

	// 0x14 Wakeup data
	for (j=0; j<16; j++) for (i=0; i<6; i++) *ptr++ = EthAddr->b[i];

	// 0x74 Password
	for (i=0; i<6; i++) *ptr++ = password->b[i];

	mDNSPlatformSendRawPacket(m->omsg.data, ptr, InterfaceID);

	// For Ethernet switches that don't flood-foward packets with unknown unicast destination MAC addresses,
	// broadcast is the only reliable way to get a wakeup packet to the intended target machine.
	// For 802.11 WPA networks, where a sleeping target machine may have missed a broadcast/multicast
	// key rotation, unicast is the only way to get a wakeup packet to the intended target machine.
	// So, we send one of each, unicast first, then broadcast second.
	for (i=0; i<6; i++) m->omsg.data[i] = 0xFF;
	mDNSPlatformSendRawPacket(m->omsg.data, ptr, InterfaceID);
	}

// ***************************************************************************
#if COMPILER_LIKES_PRAGMA_MARK
#pragma mark -
#pragma mark - RR List Management & Task Management
#endif

// Note: AnswerCurrentQuestionWithResourceRecord can call a user callback, which may change the record list and/or question list.
// Any code walking either list must use the m->CurrentQuestion (and possibly m->CurrentRecord) mechanism to protect against this.
// In fact, to enforce this, the routine will *only* answer the question currently pointed to by m->CurrentQuestion,
// which will be auto-advanced (possibly to NULL) if the client callback cancels the question.
mDNSexport void AnswerCurrentQuestionWithResourceRecord(mDNS *const m, CacheRecord *const rr, const QC_result AddRecord)
	{
	DNSQuestion *const q = m->CurrentQuestion;
	mDNSBool followcname = FollowCNAME(q, &rr->resrec, AddRecord);

	verbosedebugf("AnswerCurrentQuestionWithResourceRecord:%4lu %s TTL %d %s",
		q->CurrentAnswers, AddRecord ? "Add" : "Rmv", rr->resrec.rroriginalttl, CRDisplayString(m, rr));

	// Normally we don't send out the unicast query if we have answered using our local only auth records e.g., /etc/hosts.
	// But if the query for "A" record has a local answer but query for "AAAA" record has no local answer, we might
	// send the AAAA query out which will come back with CNAME and will also answer the "A" query. To prevent that,
	// we check to see if that query already has a unique local answer.
	if (q->LOAddressAnswers)
		{
		LogInfo("AnswerCurrentQuestionWithResourceRecord: Question %p %##s (%s) not answering with record %s due to "
			"LOAddressAnswers %d", q, q->qname.c, DNSTypeName(q->qtype), ARDisplayString(m, rr),
			q->LOAddressAnswers);
		return;
		}

	if (QuerySuppressed(q))
		{
		// If the query is suppressed, then we don't want to answer from the cache. But if this query is
		// supposed to time out, we still want to callback the clients. We do this only for TimeoutQuestions
		// that are timing out, which we know are answered with Negative cache record when timing out.
		if (!q->TimeoutQuestion || rr->resrec.RecordType != kDNSRecordTypePacketNegative || (m->timenow - q->StopTime < 0))
			return;
		}

	// Note: Use caution here. In the case of records with rr->DelayDelivery set, AnswerCurrentQuestionWithResourceRecord(... mDNStrue)
	// may be called twice, once when the record is received, and again when it's time to notify local clients.
	// If any counters or similar are added here, care must be taken to ensure that they are not double-incremented by this.

	rr->LastUsed = m->timenow;
	if (AddRecord == QC_add && !q->DuplicateOf && rr->CRActiveQuestion != q)
		{
		if (!rr->CRActiveQuestion) m->rrcache_active++;	// If not previously active, increment rrcache_active count
		debugf("AnswerCurrentQuestionWithResourceRecord: Updating CRActiveQuestion from %p to %p for cache record %s, CurrentAnswer %d",
			rr->CRActiveQuestion, q, CRDisplayString(m,rr), q->CurrentAnswers);
		rr->CRActiveQuestion = q;						// We know q is non-null
		SetNextCacheCheckTimeForRecord(m, rr);
		}

	// If this is:
	// (a) a no-cache add, where we've already done at least one 'QM' query, or
	// (b) a normal add, where we have at least one unique-type answer,
	// then there's no need to keep polling the network.
	// (If we have an answer in the cache, then we'll automatically ask again in time to stop it expiring.)
	// We do this for mDNS questions and uDNS one-shot questions, but not for
	// uDNS LongLived questions, because that would mess up our LLQ lease renewal timing.
	if ((AddRecord == QC_addnocache && !q->RequestUnicast) ||
		(AddRecord == QC_add && (q->ExpectUnique || (rr->resrec.RecordType & kDNSRecordTypePacketUniqueMask))))
		if (ActiveQuestion(q) && (mDNSOpaque16IsZero(q->TargetQID) || !q->LongLived))
			{
			q->LastQTime        = m->timenow;
			q->LastQTxTime      = m->timenow;
			q->RecentAnswerPkts = 0;
			q->ThisQInterval    = MaxQuestionInterval;
			q->RequestUnicast   = mDNSfalse;
			debugf("AnswerCurrentQuestionWithResourceRecord: Set MaxQuestionInterval for %##s (%s)", q->qname.c, DNSTypeName(q->qtype));
			}

	if (rr->DelayDelivery) return;		// We'll come back later when CacheRecordDeferredAdd() calls us

	// Only deliver negative answers if client has explicitly requested them
	if (rr->resrec.RecordType == kDNSRecordTypePacketNegative || (q->qtype != kDNSType_NSEC && RRAssertsNonexistence(&rr->resrec, q->qtype)))
		if (!AddRecord || !q->ReturnIntermed) return;

	// For CNAME results to non-CNAME questions, only inform the client if they explicitly requested that
	if (q->QuestionCallback && !q->NoAnswer && (!followcname || q->ReturnIntermed))
		{
		mDNS_DropLockBeforeCallback();		// Allow client (and us) to legally make mDNS API calls
		if (q->qtype != kDNSType_NSEC && RRAssertsNonexistence(&rr->resrec, q->qtype))
			{
			CacheRecord neg;
			MakeNegativeCacheRecord(m, &neg, &q->qname, q->qnamehash, q->qtype, q->qclass, 1, rr->resrec.InterfaceID, q->qDNSServer);
			q->QuestionCallback(m, q, &neg.resrec, AddRecord);
			}
		else
			q->QuestionCallback(m, q, &rr->resrec, AddRecord);
		mDNS_ReclaimLockAfterCallback();	// Decrement mDNS_reentrancy to block mDNS API calls again
		}
	// Note: Proceed with caution here because client callback function is allowed to do anything,
	// including starting/stopping queries, registering/deregistering records, etc.

	if (followcname && m->CurrentQuestion == q)
		AnswerQuestionByFollowingCNAME(m, q, &rr->resrec);
	}

// New Questions are answered through AnswerNewQuestion. But there may not have been any
// matching cache records for the questions when it is called. There are two possibilities.
//
// 1) There are no cache records
// 2) There are cache records but the DNSServers between question and cache record don't match.
//
// In the case of (1), where there are no cache records and later we add them when we get a response,
// CacheRecordAdd/CacheRecordDeferredAdd will take care of adding the cache and delivering the ADD
// events to the application. If we already have a cache entry, then no ADD events are delivered
// unless the RDATA has changed
//
// In the case of (2) where we had the cache records and did not answer because of the DNSServer mismatch,
// we need to answer them whenever we change the DNSServer.  But we can't do it at the instant the DNSServer
// changes because when we do the callback, the question can get deleted and the calling function would not
// know how to handle it. So, we run this function from mDNS_Execute to handle DNSServer changes on the
// question

mDNSlocal void AnswerQuestionsForDNSServerChanges(mDNS *const m)
	{
	DNSQuestion *q;
	DNSQuestion *qnext;
	CacheRecord *rr;
	mDNSu32 slot;
	CacheGroup *cg;

	if (m->CurrentQuestion)
		LogMsg("AnswerQuestionsForDNSServerChanges: ERROR m->CurrentQuestion already set: %##s (%s)",
				m->CurrentQuestion->qname.c, DNSTypeName(m->CurrentQuestion->qtype));

	for (q = m->Questions; q && q != m->NewQuestions; q = qnext)
		{
		qnext = q->next;

		// multicast or DNSServers did not change.
		if (mDNSOpaque16IsZero(q->TargetQID)) continue;
		if (!q->deliverAddEvents) continue;

		// We are going to look through the cache for this question since it changed
		// its DNSserver last time. Reset it so that we don't call them again. Calling
		// them again will deliver duplicate events to the application
		q->deliverAddEvents = mDNSfalse;
		if (QuerySuppressed(q)) continue;
		m->CurrentQuestion = q;
		slot = HashSlot(&q->qname);
		cg = CacheGroupForName(m, slot, q->qnamehash, &q->qname);
		for (rr = cg ? cg->members : mDNSNULL; rr; rr=rr->next)
			{
			if (SameNameRecordAnswersQuestion(&rr->resrec, q))
				{
				LogInfo("AnswerQuestionsForDNSServerChanges: Calling AnswerCurrentQuestionWithResourceRecord for question %p %##s using resource record %s",
					q, q->qname.c, CRDisplayString(m, rr));
				// When this question penalizes a DNS server and has no more DNS servers to pick, we normally
				// deliver a negative cache response and suspend the question for 60 seconds (see uDNS_CheckCurrentQuestion).
				// But sometimes we may already find the negative cache entry and deliver that here as the process
				// of changing DNS servers. When the cache entry is about to expire, we will resend the question and
				// that time, we need to make sure that we have a valid DNS server. Otherwise, we will deliver
				// a negative cache response without trying the server.
				if (!q->qDNSServer && !q->DuplicateOf && rr->resrec.RecordType == kDNSRecordTypePacketNegative)
					{
					DNSQuestion *qptr;
					SetValidDNSServers(m, q);
					q->qDNSServer = GetServerForQuestion(m, q);
					for (qptr = q->next ; qptr; qptr = qptr->next)
						if (qptr->DuplicateOf == q) { qptr->validDNSServers = q->validDNSServers; qptr->qDNSServer = q->qDNSServer; }
					}
				q->CurrentAnswers++;
				if (rr->resrec.rdlength > SmallRecordLimit) q->LargeAnswers++;
				if (rr->resrec.RecordType & kDNSRecordTypePacketUniqueMask) q->UniqueAnswers++;
				AnswerCurrentQuestionWithResourceRecord(m, rr, QC_add);
				if (m->CurrentQuestion != q) break;		// If callback deleted q, then we're finished here
				}
			}
		}
		m->CurrentQuestion = mDNSNULL;
	}

mDNSlocal void CacheRecordDeferredAdd(mDNS *const m, CacheRecord *rr)
	{
	rr->DelayDelivery = 0;
	if (m->CurrentQuestion)
		LogMsg("CacheRecordDeferredAdd ERROR m->CurrentQuestion already set: %##s (%s)",
			m->CurrentQuestion->qname.c, DNSTypeName(m->CurrentQuestion->qtype));
	m->CurrentQuestion = m->Questions;
	while (m->CurrentQuestion && m->CurrentQuestion != m->NewQuestions)
		{
		DNSQuestion *q = m->CurrentQuestion;
		if (ResourceRecordAnswersQuestion(&rr->resrec, q))
			AnswerCurrentQuestionWithResourceRecord(m, rr, QC_add);
		if (m->CurrentQuestion == q)	// If m->CurrentQuestion was not auto-advanced, do it ourselves now
			m->CurrentQuestion = q->next;
		}
	m->CurrentQuestion = mDNSNULL;
	}

mDNSlocal mDNSs32 CheckForSoonToExpireRecords(mDNS *const m, const domainname *const name, const mDNSu32 namehash, const mDNSu32 slot)
	{
	const mDNSs32 threshhold = m->timenow + mDNSPlatformOneSecond;	// See if there are any records expiring within one second
	const mDNSs32 start      = m->timenow - 0x10000000;
	mDNSs32 delay = start;
	CacheGroup *cg = CacheGroupForName(m, slot, namehash, name);
	const CacheRecord *rr;
	for (rr = cg ? cg->members : mDNSNULL; rr; rr=rr->next)
		if (threshhold - RRExpireTime(rr) >= 0)		// If we have records about to expire within a second
			if (delay - RRExpireTime(rr) < 0)		// then delay until after they've been deleted
				delay = RRExpireTime(rr);
	if (delay - start > 0) return(NonZeroTime(delay));
	else return(0);
	}

// CacheRecordAdd is only called from CreateNewCacheEntry, *never* directly as a result of a client API call.
// If new questions are created as a result of invoking client callbacks, they will be added to
// the end of the question list, and m->NewQuestions will be set to indicate the first new question.
// rr is a new CacheRecord just received into our cache
// (kDNSRecordTypePacketAns/PacketAnsUnique/PacketAdd/PacketAddUnique).
// Note: CacheRecordAdd calls AnswerCurrentQuestionWithResourceRecord which can call a user callback,
// which may change the record list and/or question list.
// Any code walking either list must use the CurrentQuestion and/or CurrentRecord mechanism to protect against this.
mDNSlocal void CacheRecordAdd(mDNS *const m, CacheRecord *rr)
	{
	DNSQuestion *q;

	// We stop when we get to NewQuestions -- if we increment their CurrentAnswers/LargeAnswers/UniqueAnswers
	// counters here we'll end up double-incrementing them when we do it again in AnswerNewQuestion().
	for (q = m->Questions; q && q != m->NewQuestions; q=q->next)
		{
		if (ResourceRecordAnswersQuestion(&rr->resrec, q))
			{
			// If this question is one that's actively sending queries, and it's received ten answers within one
			// second of sending the last query packet, then that indicates some radical network topology change,
			// so reset its exponential backoff back to the start. We must be at least at the eight-second interval
			// to do this. If we're at the four-second interval, or less, there's not much benefit accelerating
			// because we will anyway send another query within a few seconds. The first reset query is sent out
			// randomized over the next four seconds to reduce possible synchronization between machines.
			if (q->LastAnswerPktNum != m->PktNum)
				{
				q->LastAnswerPktNum = m->PktNum;
				if (mDNSOpaque16IsZero(q->TargetQID) && ActiveQuestion(q) && ++q->RecentAnswerPkts >= 10 &&
					q->ThisQInterval > InitialQuestionInterval * QuestionIntervalStep3 && m->timenow - q->LastQTxTime < mDNSPlatformOneSecond)
					{
					LogMsg("CacheRecordAdd: %##s (%s) got immediate answer burst (%d); restarting exponential backoff sequence (%d)",
						q->qname.c, DNSTypeName(q->qtype), q->RecentAnswerPkts, q->ThisQInterval);
					q->LastQTime      = m->timenow - InitialQuestionInterval + (mDNSs32)mDNSRandom((mDNSu32)mDNSPlatformOneSecond*4);
					q->ThisQInterval  = InitialQuestionInterval;
					SetNextQueryTime(m,q);
					}
				}
			verbosedebugf("CacheRecordAdd %p %##s (%s) %lu %#a:%d question %p", rr, rr->resrec.name->c,
				DNSTypeName(rr->resrec.rrtype), rr->resrec.rroriginalttl, rr->resrec.rDNSServer ?
				&rr->resrec.rDNSServer->addr : mDNSNULL, mDNSVal16(rr->resrec.rDNSServer ?
				rr->resrec.rDNSServer->port : zeroIPPort), q);
			q->CurrentAnswers++;
			q->unansweredQueries = 0;
			if (rr->resrec.rdlength > SmallRecordLimit) q->LargeAnswers++;
			if (rr->resrec.RecordType & kDNSRecordTypePacketUniqueMask) q->UniqueAnswers++;
			if (q->CurrentAnswers > 4000)
				{
				static int msgcount = 0;
				if (msgcount++ < 10)
					LogMsg("CacheRecordAdd: %##s (%s) has %d answers; shedding records to resist DOS attack",
						q->qname.c, DNSTypeName(q->qtype), q->CurrentAnswers);
				rr->resrec.rroriginalttl = 0;
				rr->UnansweredQueries = MaxUnansweredQueries;
				}
			}
		}

	if (!rr->DelayDelivery)
		{
		if (m->CurrentQuestion)
			LogMsg("CacheRecordAdd ERROR m->CurrentQuestion already set: %##s (%s)", m->CurrentQuestion->qname.c, DNSTypeName(m->CurrentQuestion->qtype));
		m->CurrentQuestion = m->Questions;
		while (m->CurrentQuestion && m->CurrentQuestion != m->NewQuestions)
			{
			q = m->CurrentQuestion;
			if (ResourceRecordAnswersQuestion(&rr->resrec, q))
				AnswerCurrentQuestionWithResourceRecord(m, rr, QC_add);
			if (m->CurrentQuestion == q)	// If m->CurrentQuestion was not auto-advanced, do it ourselves now
				m->CurrentQuestion = q->next;
			}
		m->CurrentQuestion = mDNSNULL;
		}

	SetNextCacheCheckTimeForRecord(m, rr);
	}

// NoCacheAnswer is only called from mDNSCoreReceiveResponse, *never* directly as a result of a client API call.
// If new questions are created as a result of invoking client callbacks, they will be added to
// the end of the question list, and m->NewQuestions will be set to indicate the first new question.
// rr is a new CacheRecord just received from the wire (kDNSRecordTypePacketAns/AnsUnique/Add/AddUnique)
// but we don't have any place to cache it. We'll deliver question 'add' events now, but we won't have any
// way to deliver 'remove' events in future, nor will we be able to include this in known-answer lists,
// so we immediately bump ThisQInterval up to MaxQuestionInterval to avoid pounding the network.
// Note: NoCacheAnswer calls AnswerCurrentQuestionWithResourceRecord which can call a user callback,
// which may change the record list and/or question list.
// Any code walking either list must use the CurrentQuestion and/or CurrentRecord mechanism to protect against this.
mDNSlocal void NoCacheAnswer(mDNS *const m, CacheRecord *rr)
	{
	LogMsg("No cache space: Delivering non-cached result for %##s", m->rec.r.resrec.name->c);
	if (m->CurrentQuestion)
		LogMsg("NoCacheAnswer ERROR m->CurrentQuestion already set: %##s (%s)", m->CurrentQuestion->qname.c, DNSTypeName(m->CurrentQuestion->qtype));
	m->CurrentQuestion = m->Questions;
	// We do this for *all* questions, not stopping when we get to m->NewQuestions,
	// since we're not caching the record and we'll get no opportunity to do this later
	while (m->CurrentQuestion)
		{
		DNSQuestion *q = m->CurrentQuestion;
		if (ResourceRecordAnswersQuestion(&rr->resrec, q))
			AnswerCurrentQuestionWithResourceRecord(m, rr, QC_addnocache);	// QC_addnocache means "don't expect remove events for this"
		if (m->CurrentQuestion == q)	// If m->CurrentQuestion was not auto-advanced, do it ourselves now
			m->CurrentQuestion = q->next;
		}
	m->CurrentQuestion = mDNSNULL;
	}

// CacheRecordRmv is only called from CheckCacheExpiration, which is called from mDNS_Execute.
// Note that CacheRecordRmv is *only* called for records that are referenced by at least one active question.
// If new questions are created as a result of invoking client callbacks, they will be added to
// the end of the question list, and m->NewQuestions will be set to indicate the first new question.
// rr is an existing cache CacheRecord that just expired and is being deleted
// (kDNSRecordTypePacketAns/PacketAnsUnique/PacketAdd/PacketAddUnique).
// Note: CacheRecordRmv calls AnswerCurrentQuestionWithResourceRecord which can call a user callback,
// which may change the record list and/or question list.
// Any code walking either list must use the CurrentQuestion and/or CurrentRecord mechanism to protect against this.
mDNSlocal void CacheRecordRmv(mDNS *const m, CacheRecord *rr)
	{
	if (m->CurrentQuestion)
		LogMsg("CacheRecordRmv ERROR m->CurrentQuestion already set: %##s (%s)",
			m->CurrentQuestion->qname.c, DNSTypeName(m->CurrentQuestion->qtype));
	m->CurrentQuestion = m->Questions;

	// We stop when we get to NewQuestions -- for new questions their CurrentAnswers/LargeAnswers/UniqueAnswers counters
	// will all still be zero because we haven't yet gone through the cache counting how many answers we have for them.
	while (m->CurrentQuestion && m->CurrentQuestion != m->NewQuestions)
		{
		DNSQuestion *q = m->CurrentQuestion;
		// When a question enters suppressed state, we generate RMV events and generate a negative
		// response. A cache may be present that answers this question e.g., cache entry generated
		// before the question became suppressed. We need to skip the suppressed questions here as
		// the RMV event has already been generated.
		if (!QuerySuppressed(q) && ResourceRecordAnswersQuestion(&rr->resrec, q))
			{
			verbosedebugf("CacheRecordRmv %p %s", rr, CRDisplayString(m, rr));
			q->FlappingInterface1 = mDNSNULL;
			q->FlappingInterface2 = mDNSNULL;

			// When a question changes DNS server, it is marked with deliverAddEvents if we find any
			// cache entry corresponding to the new DNS server. Before we deliver the ADD event, the
			// cache entry may be removed in which case CurrentAnswers can be zero.
			if (q->deliverAddEvents && !q->CurrentAnswers)
				{
				LogInfo("CacheRecordRmv: Question %p %##s (%s) deliverAddEvents set, DNSServer %#a:%d",
					q, q->qname.c, DNSTypeName(q->qtype), q->qDNSServer ? &q->qDNSServer->addr : mDNSNULL,
					mDNSVal16(q->qDNSServer ? q->qDNSServer->port : zeroIPPort));
				m->CurrentQuestion = q->next;
				continue;
				}
			if (q->CurrentAnswers == 0)
				LogMsg("CacheRecordRmv ERROR!!: How can CurrentAnswers already be zero for %p %##s (%s) DNSServer %#a:%d",
					q, q->qname.c, DNSTypeName(q->qtype), q->qDNSServer ? &q->qDNSServer->addr : mDNSNULL,
					mDNSVal16(q->qDNSServer ? q->qDNSServer->port : zeroIPPort));
			else
				{
				q->CurrentAnswers--;
				if (rr->resrec.rdlength > SmallRecordLimit) q->LargeAnswers--;
				if (rr->resrec.RecordType & kDNSRecordTypePacketUniqueMask) q->UniqueAnswers--;
				}
			if (rr->resrec.rdata->MaxRDLength) // Never generate "remove" events for negative results
				{
				if (q->CurrentAnswers == 0)
					{
					LogInfo("CacheRecordRmv: Last answer for %##s (%s) expired from cache; will reconfirm antecedents",
						q->qname.c, DNSTypeName(q->qtype));
					ReconfirmAntecedents(m, &q->qname, q->qnamehash, 0);
					}
				AnswerCurrentQuestionWithResourceRecord(m, rr, QC_rmv);
				}
			}
		if (m->CurrentQuestion == q)	// If m->CurrentQuestion was not auto-advanced, do it ourselves now
			m->CurrentQuestion = q->next;
		}
	m->CurrentQuestion = mDNSNULL;
	}

mDNSlocal void ReleaseCacheEntity(mDNS *const m, CacheEntity *e)
	{
#if APPLE_OSX_mDNSResponder && MACOSX_MDNS_MALLOC_DEBUGGING >= 1
	unsigned int i;
	for (i=0; i<sizeof(*e); i++) ((char*)e)[i] = 0xFF;
#endif
	e->next = m->rrcache_free;
	m->rrcache_free = e;
	m->rrcache_totalused--;
	}

mDNSlocal void ReleaseCacheGroup(mDNS *const m, CacheGroup **cp)
	{
	CacheEntity *e = (CacheEntity *)(*cp);
	//LogMsg("ReleaseCacheGroup:  Releasing CacheGroup for %p, %##s", (*cp)->name->c, (*cp)->name->c);
	if ((*cp)->rrcache_tail != &(*cp)->members)
		LogMsg("ERROR: (*cp)->members == mDNSNULL but (*cp)->rrcache_tail != &(*cp)->members)");
	//if ((*cp)->name != (domainname*)((*cp)->namestorage))
	//	LogMsg("ReleaseCacheGroup: %##s, %p %p", (*cp)->name->c, (*cp)->name, (domainname*)((*cp)->namestorage));
	if ((*cp)->name != (domainname*)((*cp)->namestorage)) mDNSPlatformMemFree((*cp)->name);
	(*cp)->name = mDNSNULL;
	*cp = (*cp)->next;			// Cut record from list
	ReleaseCacheEntity(m, e);
	}

mDNSlocal void ReleaseCacheRecord(mDNS *const m, CacheRecord *r)
	{
	//LogMsg("ReleaseCacheRecord: Releasing %s", CRDisplayString(m, r));
	if (r->resrec.rdata && r->resrec.rdata != (RData*)&r->smallrdatastorage) mDNSPlatformMemFree(r->resrec.rdata);
	r->resrec.rdata = mDNSNULL;
	ReleaseCacheEntity(m, (CacheEntity *)r);
	}

// Note: We want to be careful that we deliver all the CacheRecordRmv calls before delivering
// CacheRecordDeferredAdd calls. The in-order nature of the cache lists ensures that all
// callbacks for old records are delivered before callbacks for newer records.
mDNSlocal void CheckCacheExpiration(mDNS *const m, const mDNSu32 slot, CacheGroup *const cg)
	{
	CacheRecord **rp = &cg->members;

	if (m->lock_rrcache) { LogMsg("CheckCacheExpiration ERROR! Cache already locked!"); return; }
	m->lock_rrcache = 1;

	while (*rp)
		{
		CacheRecord *const rr = *rp;
		mDNSs32 event = RRExpireTime(rr);
		if (m->timenow - event >= 0)	// If expired, delete it
			{
			*rp = rr->next;				// Cut it from the list
			verbosedebugf("CheckCacheExpiration: Deleting%7d %7d %p %s",
				m->timenow - rr->TimeRcvd, rr->resrec.rroriginalttl, rr->CRActiveQuestion, CRDisplayString(m, rr));
			if (rr->CRActiveQuestion)	// If this record has one or more active questions, tell them it's going away
				{
				DNSQuestion *q = rr->CRActiveQuestion;
				// When a cache record is about to expire, we expect to do four queries at 80-82%, 85-87%, 90-92% and
				// then 95-97% of the TTL. If the DNS server does not respond, then we will remove the cache entry
				// before we pick a new DNS server. As the question interval is set to MaxQuestionInterval, we may
				// not send out a query anytime soon. Hence, we need to reset the question interval. If this is
				// a normal deferred ADD case, then AnswerCurrentQuestionWithResourceRecord will reset it to
				// MaxQuestionInterval. If we have inactive questions referring to negative cache entries,
				// don't ressurect them as they will deliver duplicate "No such Record" ADD events
				if (!mDNSOpaque16IsZero(q->TargetQID) && !q->LongLived && ActiveQuestion(q))
					{
					q->ThisQInterval = InitialQuestionInterval;
					q->LastQTime     = m->timenow - q->ThisQInterval;
					SetNextQueryTime(m, q);
					}
				CacheRecordRmv(m, rr);
				m->rrcache_active--;
				}
			ReleaseCacheRecord(m, rr);
			}
		else							// else, not expired; see if we need to query
			{
			// If waiting to delay delivery, do nothing until then
			if (rr->DelayDelivery && rr->DelayDelivery - m->timenow > 0)
				event = rr->DelayDelivery;
			else
				{
				if (rr->DelayDelivery) CacheRecordDeferredAdd(m, rr);
				if (rr->CRActiveQuestion && rr->UnansweredQueries < MaxUnansweredQueries)
					{
					if (m->timenow - rr->NextRequiredQuery < 0)		// If not yet time for next query
						event = NextCacheCheckEvent(rr);			// then just record when we want the next query
					else											// else trigger our question to go out now
						{
						// Set NextScheduledQuery to timenow so that SendQueries() will run.
						// SendQueries() will see that we have records close to expiration, and send FEQs for them.
						m->NextScheduledQuery = m->timenow;
						// After sending the query we'll increment UnansweredQueries and call SetNextCacheCheckTimeForRecord(),
						// which will correctly update m->NextCacheCheck for us.
						event = m->timenow + 0x3FFFFFFF;
						}
					}
				}
			verbosedebugf("CheckCacheExpiration:%6d %5d %s",
				(event - m->timenow) / mDNSPlatformOneSecond, CacheCheckGracePeriod(rr), CRDisplayString(m, rr));
			if (m->rrcache_nextcheck[slot] - event > 0)
				m->rrcache_nextcheck[slot] = event;
			rp = &rr->next;
			}
		}
	if (cg->rrcache_tail != rp) verbosedebugf("CheckCacheExpiration: Updating CacheGroup tail from %p to %p", cg->rrcache_tail, rp);
	cg->rrcache_tail = rp;
	m->lock_rrcache = 0;
	}

mDNSlocal void AnswerNewQuestion(mDNS *const m)
	{
	mDNSBool ShouldQueryImmediately = mDNStrue;
	DNSQuestion *const q = m->NewQuestions;		// Grab the question we're going to answer
	mDNSu32 slot = HashSlot(&q->qname);
	CacheGroup *const cg = CacheGroupForName(m, slot, q->qnamehash, &q->qname);
	AuthRecord *lr;
	AuthGroup *ag;
	mDNSBool AnsweredFromCache = mDNSfalse;

	verbosedebugf("AnswerNewQuestion: Answering %##s (%s)", q->qname.c, DNSTypeName(q->qtype));

	if (cg) CheckCacheExpiration(m, slot, cg);
	if (m->NewQuestions != q) { LogInfo("AnswerNewQuestion: Question deleted while doing CheckCacheExpiration"); goto exit; }
	m->NewQuestions = q->next;
	// Advance NewQuestions to the next *after* calling CheckCacheExpiration, because if we advance it first
	// then CheckCacheExpiration may give this question add/remove callbacks, and it's not yet ready for that.
	//
	// Also, CheckCacheExpiration() calls CacheRecordDeferredAdd() and CacheRecordRmv(), which invoke
	// client callbacks, which may delete their own or any other question. Our mechanism for detecting
	// whether our current m->NewQuestions question got deleted by one of these callbacks is to store the
	// value of m->NewQuestions in 'q' before calling CheckCacheExpiration(), and then verify afterwards
	// that they're still the same. If m->NewQuestions has changed (because mDNS_StopQuery_internal
	// advanced it), that means the question was deleted, so we no longer need to worry about answering
	// it (and indeed 'q' is now a dangling pointer, so dereferencing it at all would be bad, and the
	// values we computed for slot and cg are now stale and relate to a question that no longer exists).
	//
	// We can't use the usual m->CurrentQuestion mechanism for this because  CacheRecordDeferredAdd() and
	// CacheRecordRmv() both use that themselves when walking the list of (non-new) questions generating callbacks.
	// Fortunately mDNS_StopQuery_internal auto-advances both m->CurrentQuestion *AND* m->NewQuestions when
	// deleting a question, so luckily we have an easy alternative way of detecting if our question got deleted.

	if (m->lock_rrcache) LogMsg("AnswerNewQuestion ERROR! Cache already locked!");
	// This should be safe, because calling the client's question callback may cause the
	// question list to be modified, but should not ever cause the rrcache list to be modified.
	// If the client's question callback deletes the question, then m->CurrentQuestion will
	// be advanced, and we'll exit out of the loop
	m->lock_rrcache = 1;
	if (m->CurrentQuestion)
		LogMsg("AnswerNewQuestion ERROR m->CurrentQuestion already set: %##s (%s)",
			m->CurrentQuestion->qname.c, DNSTypeName(m->CurrentQuestion->qtype));
	m->CurrentQuestion = q;		// Indicate which question we're answering, so we'll know if it gets deleted

	if (q->NoAnswer == NoAnswer_Fail)
		{
		LogMsg("AnswerNewQuestion: NoAnswer_Fail %##s (%s)", q->qname.c, DNSTypeName(q->qtype));
		MakeNegativeCacheRecord(m, &m->rec.r, &q->qname, q->qnamehash, q->qtype, q->qclass, 60, mDNSInterface_Any, q->qDNSServer);
		q->NoAnswer = NoAnswer_Normal;		// Temporarily turn off answer suppression
		AnswerCurrentQuestionWithResourceRecord(m, &m->rec.r, QC_addnocache);
		// Don't touch the question if it has been stopped already
		if (m->CurrentQuestion == q) q->NoAnswer = NoAnswer_Fail;		// Restore NoAnswer state
		m->rec.r.resrec.RecordType = 0;		// Clear RecordType to show we're not still using it
		}
	if (m->CurrentQuestion != q) { LogInfo("AnswerNewQuestion: Question deleted while generating NoAnswer_Fail response"); goto exit; }

	// See if we want to tell it about LocalOnly records
	if (m->CurrentRecord)
		LogMsg("AnswerNewQuestion ERROR m->CurrentRecord already set %s", ARDisplayString(m, m->CurrentRecord));
	slot = AuthHashSlot(&q->qname);
	ag = AuthGroupForName(&m->rrauth, slot, q->qnamehash, &q->qname);
	if (ag)
		{
		m->CurrentRecord = ag->members;
		while (m->CurrentRecord && m->CurrentRecord != ag->NewLocalOnlyRecords)
			{
			AuthRecord *rr = m->CurrentRecord;
			m->CurrentRecord = rr->next;
			//
			// If the question is mDNSInterface_LocalOnly, all records local to the machine should be used
			// to answer the query. This is handled in AnswerNewLocalOnlyQuestion.
			//
			// We handle mDNSInterface_Any and scoped questions here. See LocalOnlyRecordAnswersQuestion for more
			// details on how we handle this case. For P2P we just handle "Interface_Any" questions. For LocalOnly
			// we handle both mDNSInterface_Any and scoped questions.

			if (rr->ARType == AuthRecordLocalOnly || (rr->ARType == AuthRecordP2P && q->InterfaceID == mDNSInterface_Any))
				if (LocalOnlyRecordAnswersQuestion(rr, q))
					{
					AnswerLocalQuestionWithLocalAuthRecord(m, rr, mDNStrue);
					if (m->CurrentQuestion != q) break;		// If callback deleted q, then we're finished here
					}
			}
		}
	m->CurrentRecord = mDNSNULL;

	if (m->CurrentQuestion != q) { LogInfo("AnswerNewQuestion: Question deleted while while giving LocalOnly record answers"); goto exit; }

	if (q->LOAddressAnswers)
		{
		LogInfo("AnswerNewQuestion: Question %p %##s (%s) answered using local auth records LOAddressAnswers %d",
			q, q->qname.c, DNSTypeName(q->qtype), q->LOAddressAnswers);
		goto exit;
		}

	// Before we go check the cache and ship this query on the wire, we have to be sure that there are
	// no local records that could possibly answer this question. As we did not check the NewLocalRecords, we
	// need to just peek at them to see whether it will answer this question. If it would answer, pretend
	// that we answered. AnswerAllLocalQuestionsWithLocalAuthRecord will answer shortly. This happens normally
	// when we add new /etc/hosts entries and restart the question. It is a new question and also a new record.
	if (ag)
		{
		lr = ag->NewLocalOnlyRecords;
		while (lr)
			{
			if (LORecordAnswersAddressType(lr) && LocalOnlyRecordAnswersQuestion(lr, q))
				{
				LogInfo("AnswerNewQuestion: Question %p %##s (%s) will be answered using new local auth records "
					" LOAddressAnswers %d", q, q->qname.c, DNSTypeName(q->qtype), q->LOAddressAnswers);
				goto exit;
				}
			lr = lr->next;
			}
		}


	// If we are not supposed to answer this question, generate a negative response.
	// Temporarily suspend the SuppressQuery so that AnswerCurrentQuestionWithResourceRecord can answer the question
	if (QuerySuppressed(q)) { q->SuppressQuery = mDNSfalse; GenerateNegativeResponse(m); q->SuppressQuery = mDNStrue; }
	else
		{
		CacheRecord *rr;
		for (rr = cg ? cg->members : mDNSNULL; rr; rr=rr->next)
			if (SameNameRecordAnswersQuestion(&rr->resrec, q))
				{
				// SecsSinceRcvd is whole number of elapsed seconds, rounded down
				mDNSu32 SecsSinceRcvd = ((mDNSu32)(m->timenow - rr->TimeRcvd)) / mDNSPlatformOneSecond;
				if (rr->resrec.rroriginalttl <= SecsSinceRcvd)
					{
					LogMsg("AnswerNewQuestion: How is rr->resrec.rroriginalttl %lu <= SecsSinceRcvd %lu for %s %d %d",
						rr->resrec.rroriginalttl, SecsSinceRcvd, CRDisplayString(m, rr), m->timenow, rr->TimeRcvd);
					continue;	// Go to next one in loop
					}

				// If this record set is marked unique, then that means we can reasonably assume we have the whole set
				// -- we don't need to rush out on the network and query immediately to see if there are more answers out there
				if ((rr->resrec.RecordType & kDNSRecordTypePacketUniqueMask) || (q->ExpectUnique))
					ShouldQueryImmediately = mDNSfalse;
				q->CurrentAnswers++;
				if (rr->resrec.rdlength > SmallRecordLimit) q->LargeAnswers++;
				if (rr->resrec.RecordType & kDNSRecordTypePacketUniqueMask) q->UniqueAnswers++;
				AnsweredFromCache = mDNStrue;
				AnswerCurrentQuestionWithResourceRecord(m, rr, QC_add);
				if (m->CurrentQuestion != q) break;		// If callback deleted q, then we're finished here
				}
			else if (RRTypeIsAddressType(rr->resrec.rrtype) && RRTypeIsAddressType(q->qtype))
				ShouldQueryImmediately = mDNSfalse;
		}
	// We don't use LogInfo for this "Question deleted" message because it happens so routinely that
	// it's not remotely remarkable, and therefore unlikely to be of much help tracking down bugs.
	if (m->CurrentQuestion != q) { debugf("AnswerNewQuestion: Question deleted while giving cache answers"); goto exit; }

	// Neither a local record nor a cache entry could answer this question. If this question need to be retried
	// with search domains, generate a negative response which will now retry after appending search domains.
	// If the query was suppressed above, we already generated a negative response. When it gets unsuppressed,
	// we will retry with search domains.
	if (!QuerySuppressed(q) && !AnsweredFromCache && q->RetryWithSearchDomains)
		{
		LogInfo("AnswerNewQuestion: Generating response for retrying with search domains %##s (%s)", q->qname.c, DNSTypeName(q->qtype));
		GenerateNegativeResponse(m);
		}

	if (m->CurrentQuestion != q) { debugf("AnswerNewQuestion: Question deleted while giving negative answer"); goto exit; }

	// Note: When a query gets suppressed or retried with search domains, we de-activate the question.
	// Hence we don't execute the following block of code for those cases.
	if (ShouldQueryImmediately && ActiveQuestion(q))
		{
		debugf("AnswerNewQuestion: ShouldQueryImmediately %##s (%s)", q->qname.c, DNSTypeName(q->qtype));
		q->ThisQInterval  = InitialQuestionInterval;
		q->LastQTime      = m->timenow - q->ThisQInterval;
		if (mDNSOpaque16IsZero(q->TargetQID))		// For mDNS, spread packets to avoid a burst of simultaneous queries
			{
			// Compute random delay in the range 1-6 seconds, then divide by 50 to get 20-120ms
			if (!m->RandomQueryDelay)
				m->RandomQueryDelay = (mDNSPlatformOneSecond + mDNSRandom(mDNSPlatformOneSecond*5) - 1) / 50 + 1;
			q->LastQTime += m->RandomQueryDelay;
			}
		}

	// IN ALL CASES make sure that m->NextScheduledQuery is set appropriately.
	// In cases where m->NewQuestions->DelayAnswering is set, we may have delayed generating our
	// answers for this question until *after* its scheduled transmission time, in which case
	// m->NextScheduledQuery may now be set to 'never', and in that case -- even though we're *not* doing
	// ShouldQueryImmediately -- we still need to make sure we set m->NextScheduledQuery correctly.
	SetNextQueryTime(m,q);

exit:
	m->CurrentQuestion = mDNSNULL;
	m->lock_rrcache = 0;
	}

// When a NewLocalOnlyQuestion is created, AnswerNewLocalOnlyQuestion runs though our ResourceRecords delivering any
// appropriate answers, stopping if it reaches a NewLocalOnlyRecord -- these will be handled by AnswerAllLocalQuestionsWithLocalAuthRecord
mDNSlocal void AnswerNewLocalOnlyQuestion(mDNS *const m)
	{
	mDNSu32 slot;
	AuthGroup *ag;
	DNSQuestion *q = m->NewLocalOnlyQuestions;		// Grab the question we're going to answer
	m->NewLocalOnlyQuestions = q->next;				// Advance NewLocalOnlyQuestions to the next (if any)

	debugf("AnswerNewLocalOnlyQuestion: Answering %##s (%s)", q->qname.c, DNSTypeName(q->qtype));

	if (m->CurrentQuestion)
		LogMsg("AnswerNewLocalOnlyQuestion ERROR m->CurrentQuestion already set: %##s (%s)",
			m->CurrentQuestion->qname.c, DNSTypeName(m->CurrentQuestion->qtype));
	m->CurrentQuestion = q;		// Indicate which question we're answering, so we'll know if it gets deleted

	if (m->CurrentRecord)
		LogMsg("AnswerNewLocalOnlyQuestion ERROR m->CurrentRecord already set %s", ARDisplayString(m, m->CurrentRecord));

	// 1. First walk the LocalOnly records answering the LocalOnly question
	// 2. As LocalOnly questions should also be answered by any other Auth records local to the machine,
	//    walk the ResourceRecords list delivering the answers
	slot = AuthHashSlot(&q->qname);
	ag = AuthGroupForName(&m->rrauth, slot, q->qnamehash, &q->qname);
	if (ag)
		{
		m->CurrentRecord = ag->members;
		while (m->CurrentRecord && m->CurrentRecord != ag->NewLocalOnlyRecords)
			{
			AuthRecord *rr = m->CurrentRecord;
			m->CurrentRecord = rr->next;
			if (LocalOnlyRecordAnswersQuestion(rr, q))
				{
				AnswerLocalQuestionWithLocalAuthRecord(m, rr, mDNStrue);
				if (m->CurrentQuestion != q) break;		// If callback deleted q, then we're finished here
				}
			}
		}

	if (m->CurrentQuestion == q)
		{
		m->CurrentRecord = m->ResourceRecords;

		while (m->CurrentRecord && m->CurrentRecord != m->NewLocalRecords)
			{
			AuthRecord *rr = m->CurrentRecord;
			m->CurrentRecord = rr->next;
			if (ResourceRecordAnswersQuestion(&rr->resrec, q))
				{
				AnswerLocalQuestionWithLocalAuthRecord(m, rr, mDNStrue);
				if (m->CurrentQuestion != q) break;		// If callback deleted q, then we're finished here
				}
			}
		}

	m->CurrentQuestion = mDNSNULL;
	m->CurrentRecord   = mDNSNULL;
	}

mDNSlocal CacheEntity *GetCacheEntity(mDNS *const m, const CacheGroup *const PreserveCG)
	{
	CacheEntity *e = mDNSNULL;

	if (m->lock_rrcache) { LogMsg("GetFreeCacheRR ERROR! Cache already locked!"); return(mDNSNULL); }
	m->lock_rrcache = 1;

	// If we have no free records, ask the client layer to give us some more memory
	if (!m->rrcache_free && m->MainCallback)
		{
		if (m->rrcache_totalused != m->rrcache_size)
			LogMsg("GetFreeCacheRR: count mismatch: m->rrcache_totalused %lu != m->rrcache_size %lu",
				m->rrcache_totalused, m->rrcache_size);

		// We don't want to be vulnerable to a malicious attacker flooding us with an infinite
		// number of bogus records so that we keep growing our cache until the machine runs out of memory.
		// To guard against this, if our cache grows above 512kB (approx 3168 records at 164 bytes each),
		// and we're actively using less than 1/32 of that cache, then we purge all the unused records
		// and recycle them, instead of allocating more memory.
		if (m->rrcache_size > 5000 && m->rrcache_size / 32 > m->rrcache_active)
			LogInfo("Possible denial-of-service attack in progress: m->rrcache_size %lu; m->rrcache_active %lu",
				m->rrcache_size, m->rrcache_active);
		else
			{
			mDNS_DropLockBeforeCallback();		// Allow client to legally make mDNS API calls from the callback
			m->MainCallback(m, mStatus_GrowCache);
			mDNS_ReclaimLockAfterCallback();	// Decrement mDNS_reentrancy to block mDNS API calls again
			}
		}

	// If we still have no free records, recycle all the records we can.
	// Enumerating the entire cache is moderately expensive, so when we do it, we reclaim all the records we can in one pass.
	if (!m->rrcache_free)
		{
		mDNSu32 oldtotalused = m->rrcache_totalused;
		mDNSu32 slot;
		for (slot = 0; slot < CACHE_HASH_SLOTS; slot++)
			{
			CacheGroup **cp = &m->rrcache_hash[slot];
			while (*cp)
				{
				CacheRecord **rp = &(*cp)->members;
				while (*rp)
					{
					// Records that answer still-active questions are not candidates for recycling
					// Records that are currently linked into the CacheFlushRecords list may not be recycled, or we'll crash
					if ((*rp)->CRActiveQuestion || (*rp)->NextInCFList)
						rp=&(*rp)->next;
					else
						{
						CacheRecord *rr = *rp;
						*rp = (*rp)->next;			// Cut record from list
						ReleaseCacheRecord(m, rr);
						}
					}
				if ((*cp)->rrcache_tail != rp)
					verbosedebugf("GetFreeCacheRR: Updating rrcache_tail[%lu] from %p to %p", slot, (*cp)->rrcache_tail, rp);
				(*cp)->rrcache_tail = rp;
				if ((*cp)->members || (*cp)==PreserveCG) cp=&(*cp)->next;
				else ReleaseCacheGroup(m, cp);
				}
			}
		LogInfo("GetCacheEntity recycled %d records to reduce cache from %d to %d",
			oldtotalused - m->rrcache_totalused, oldtotalused, m->rrcache_totalused);
		}

	if (m->rrcache_free)	// If there are records in the free list, take one
		{
		e = m->rrcache_free;
		m->rrcache_free = e->next;
		if (++m->rrcache_totalused >= m->rrcache_report)
			{
			LogInfo("RR Cache now using %ld objects", m->rrcache_totalused);
			if      (m->rrcache_report <  100) m->rrcache_report += 10;
			else if (m->rrcache_report < 1000) m->rrcache_report += 100;
			else                               m->rrcache_report += 1000;
			}
		mDNSPlatformMemZero(e, sizeof(*e));
		}

	m->lock_rrcache = 0;

	return(e);
	}

mDNSlocal CacheRecord *GetCacheRecord(mDNS *const m, CacheGroup *cg, mDNSu16 RDLength)
	{
	CacheRecord *r = (CacheRecord *)GetCacheEntity(m, cg);
	if (r)
		{
		r->resrec.rdata = (RData*)&r->smallrdatastorage;	// By default, assume we're usually going to be using local storage
		if (RDLength > InlineCacheRDSize)			// If RDLength is too big, allocate extra storage
			{
			r->resrec.rdata = (RData*)mDNSPlatformMemAllocate(sizeofRDataHeader + RDLength);
			if (r->resrec.rdata) r->resrec.rdata->MaxRDLength = r->resrec.rdlength = RDLength;
			else { ReleaseCacheEntity(m, (CacheEntity*)r); r = mDNSNULL; }
			}
		}
	return(r);
	}

mDNSlocal CacheGroup *GetCacheGroup(mDNS *const m, const mDNSu32 slot, const ResourceRecord *const rr)
	{
	mDNSu16 namelen = DomainNameLength(rr->name);
	CacheGroup *cg = (CacheGroup*)GetCacheEntity(m, mDNSNULL);
	if (!cg) { LogMsg("GetCacheGroup: Failed to allocate memory for %##s", rr->name->c); return(mDNSNULL); }
	cg->next         = m->rrcache_hash[slot];
	cg->namehash     = rr->namehash;
	cg->members      = mDNSNULL;
	cg->rrcache_tail = &cg->members;
	cg->name         = (domainname*)cg->namestorage;
	//LogMsg("GetCacheGroup: %-10s %d-byte cache name %##s",
	//	(namelen > InlineCacheGroupNameSize) ? "Allocating" : "Inline", namelen, rr->name->c);
	if (namelen > InlineCacheGroupNameSize) cg->name = mDNSPlatformMemAllocate(namelen);
	if (!cg->name)
		{
		LogMsg("GetCacheGroup: Failed to allocate name storage for %##s", rr->name->c);
		ReleaseCacheEntity(m, (CacheEntity*)cg);
		return(mDNSNULL);
		}
	AssignDomainName(cg->name, rr->name);

	if (CacheGroupForRecord(m, slot, rr)) LogMsg("GetCacheGroup: Already have CacheGroup for %##s", rr->name->c);
	m->rrcache_hash[slot] = cg;
	if (CacheGroupForRecord(m, slot, rr) != cg) LogMsg("GetCacheGroup: Not finding CacheGroup for %##s", rr->name->c);

	return(cg);
	}

mDNSexport void mDNS_PurgeCacheResourceRecord(mDNS *const m, CacheRecord *rr)
	{
	if (m->mDNS_busy != m->mDNS_reentrancy+1)
		LogMsg("mDNS_PurgeCacheResourceRecord: Lock not held! mDNS_busy (%ld) mDNS_reentrancy (%ld)", m->mDNS_busy, m->mDNS_reentrancy);
	// Make sure we mark this record as thoroughly expired -- we don't ever want to give
	// a positive answer using an expired record (e.g. from an interface that has gone away).
	// We don't want to clear CRActiveQuestion here, because that would leave the record subject to
	// summary deletion without giving the proper callback to any questions that are monitoring it.
	// By setting UnansweredQueries to MaxUnansweredQueries we ensure it won't trigger any further expiration queries.
	rr->TimeRcvd          = m->timenow - mDNSPlatformOneSecond * 60;
	rr->UnansweredQueries = MaxUnansweredQueries;
	rr->resrec.rroriginalttl     = 0;
	SetNextCacheCheckTimeForRecord(m, rr);
	}

mDNSexport mDNSs32 mDNS_TimeNow(const mDNS *const m)
	{
	mDNSs32 time;
	mDNSPlatformLock(m);
	if (m->mDNS_busy)
		{
		LogMsg("mDNS_TimeNow called while holding mDNS lock. This is incorrect. Code protected by lock should just use m->timenow.");
		if (!m->timenow) LogMsg("mDNS_TimeNow: m->mDNS_busy is %ld but m->timenow not set", m->mDNS_busy);
		}

	if (m->timenow) time = m->timenow;
	else            time = mDNS_TimeNow_NoLock(m);
	mDNSPlatformUnlock(m);
	return(time);
	}

// To avoid pointless CPU thrash, we use SetSPSProxyListChanged(X) to record the last interface that
// had its Sleep Proxy client list change, and defer to actual BPF reconfiguration to mDNS_Execute().
// (GetNextScheduledEvent() returns "now" when m->SPSProxyListChanged is set)
#define SetSPSProxyListChanged(X) do { \
	if (m->SPSProxyListChanged && m->SPSProxyListChanged != (X)) mDNSPlatformUpdateProxyList(m, m->SPSProxyListChanged); \
	m->SPSProxyListChanged = (X); } while(0)

// Called from mDNS_Execute() to expire stale proxy records
mDNSlocal void CheckProxyRecords(mDNS *const m, AuthRecord *list)
	{
	m->CurrentRecord = list;
	while (m->CurrentRecord)
		{
		AuthRecord *rr = m->CurrentRecord;
		if (rr->resrec.RecordType != kDNSRecordTypeDeregistering && rr->WakeUp.HMAC.l[0])
			{
			// If m->SPSSocket is NULL that means we're not acting as a sleep proxy any more,
			// so we need to cease proxying for *all* records we may have, expired or not.
			if (m->SPSSocket && m->timenow - rr->TimeExpire < 0)	// If proxy record not expired yet, update m->NextScheduledSPS
				{
				if (m->NextScheduledSPS - rr->TimeExpire > 0)
					m->NextScheduledSPS = rr->TimeExpire;
				}
			else													// else proxy record expired, so remove it
				{
				LogSPS("CheckProxyRecords: Removing %d H-MAC %.6a I-MAC %.6a %d %s",
					m->ProxyRecords, &rr->WakeUp.HMAC, &rr->WakeUp.IMAC, rr->WakeUp.seq, ARDisplayString(m, rr));
				SetSPSProxyListChanged(rr->resrec.InterfaceID);
				mDNS_Deregister_internal(m, rr, mDNS_Dereg_normal);
				// Don't touch rr after this -- memory may have been free'd
				}
			}
		// Mustn't advance m->CurrentRecord until *after* mDNS_Deregister_internal, because
		// new records could have been added to the end of the list as a result of that call.
		if (m->CurrentRecord == rr) // If m->CurrentRecord was not advanced for us, do it now
			m->CurrentRecord = rr->next;
		}
	}

mDNSlocal void CheckRmvEventsForLocalRecords(mDNS *const m)
	{
	while (m->CurrentRecord)
		{
		AuthRecord *rr = m->CurrentRecord;
		if (rr->AnsweredLocalQ && rr->resrec.RecordType == kDNSRecordTypeDeregistering)
			{
			debugf("CheckRmvEventsForLocalRecords: Generating local RMV events for %s", ARDisplayString(m, rr));
			rr->resrec.RecordType = kDNSRecordTypeShared;
			AnswerAllLocalQuestionsWithLocalAuthRecord(m, rr, mDNSfalse);
			if (m->CurrentRecord == rr)	// If rr still exists in list, restore its state now
				{
				rr->resrec.RecordType = kDNSRecordTypeDeregistering;
				rr->AnsweredLocalQ = mDNSfalse;
				// SendResponses normally calls CompleteDeregistration after sending goodbyes.
				// For LocalOnly records, we don't do that and hence we need to do that here.
				if (RRLocalOnly(rr)) CompleteDeregistration(m, rr);
				}
			}
		if (m->CurrentRecord == rr)		// If m->CurrentRecord was not auto-advanced, do it ourselves now
			m->CurrentRecord = rr->next;
		}
	}

mDNSlocal void TimeoutQuestions(mDNS *const m)
	{
	m->NextScheduledStopTime = m->timenow + 0x3FFFFFFF;
	if (m->CurrentQuestion)
		LogMsg("TimeoutQuestions ERROR m->CurrentQuestion already set: %##s (%s)", m->CurrentQuestion->qname.c,
			DNSTypeName(m->CurrentQuestion->qtype));
	m->CurrentQuestion = m->Questions;
	while (m->CurrentQuestion)
		{
		DNSQuestion *const q = m->CurrentQuestion;
		if (q->StopTime)
			{
			if (m->timenow - q->StopTime >= 0)
				{
				LogInfo("TimeoutQuestions: question %##s timed out, time %d", q->qname.c, m->timenow - q->StopTime);
				GenerateNegativeResponse(m);
				if (m->CurrentQuestion == q) q->StopTime = 0;
				}
			else
				{
				if (m->NextScheduledStopTime - q->StopTime > 0)
					m->NextScheduledStopTime = q->StopTime;
				}
			}
		// If m->CurrentQuestion wasn't modified out from under us, advance it now
		// We can't do this at the start of the loop because GenerateNegativeResponse
		// depends on having m->CurrentQuestion point to the right question
		if (m->CurrentQuestion == q)
			m->CurrentQuestion = q->next;
		}
	m->CurrentQuestion = mDNSNULL;
	}

mDNSexport mDNSs32 mDNS_Execute(mDNS *const m)
	{
	mDNS_Lock(m);	// Must grab lock before trying to read m->timenow

	if (m->timenow - m->NextScheduledEvent >= 0)
		{
		int i;
		AuthRecord *head, *tail;
		mDNSu32 slot;
		AuthGroup *ag;

		verbosedebugf("mDNS_Execute");

		if (m->CurrentQuestion)
			LogMsg("mDNS_Execute: ERROR m->CurrentQuestion already set: %##s (%s)",
				m->CurrentQuestion->qname.c, DNSTypeName(m->CurrentQuestion->qtype));

		if (m->CurrentRecord)
			LogMsg("mDNS_Execute: ERROR m->CurrentRecord already set: %s", ARDisplayString(m, m->CurrentRecord));

		// 1. If we're past the probe suppression time, we can clear it
		if (m->SuppressProbes && m->timenow - m->SuppressProbes >= 0) m->SuppressProbes = 0;

		// 2. If it's been more than ten seconds since the last probe failure, we can clear the counter
		if (m->NumFailedProbes && m->timenow - m->ProbeFailTime >= mDNSPlatformOneSecond * 10) m->NumFailedProbes = 0;

		// 3. Purge our cache of stale old records
		if (m->rrcache_size && m->timenow - m->NextCacheCheck >= 0)
			{
			mDNSu32 numchecked = 0;
			m->NextCacheCheck = m->timenow + 0x3FFFFFFF;
			for (slot = 0; slot < CACHE_HASH_SLOTS; slot++)
				{
				if (m->timenow - m->rrcache_nextcheck[slot] >= 0)
					{
					CacheGroup **cp = &m->rrcache_hash[slot];
					m->rrcache_nextcheck[slot] = m->timenow + 0x3FFFFFFF;
					while (*cp)
						{
						debugf("m->NextCacheCheck %4d Slot %3d %##s", numchecked, slot, *cp ? (*cp)->name : (domainname*)"\x04NULL");
						numchecked++;
						CheckCacheExpiration(m, slot, *cp);
						if ((*cp)->members) cp=&(*cp)->next;
						else ReleaseCacheGroup(m, cp);
						}
					}
				// Even if we didn't need to actually check this slot yet, still need to
				// factor its nextcheck time into our overall NextCacheCheck value
				if (m->NextCacheCheck - m->rrcache_nextcheck[slot] > 0)
					m->NextCacheCheck = m->rrcache_nextcheck[slot];
				}
			debugf("m->NextCacheCheck %4d checked, next in %d", numchecked, m->NextCacheCheck - m->timenow);
			}

		if (m->timenow - m->NextScheduledSPS >= 0)
			{
			m->NextScheduledSPS = m->timenow + 0x3FFFFFFF;
			CheckProxyRecords(m, m->DuplicateRecords);	// Clear m->DuplicateRecords first, then m->ResourceRecords
			CheckProxyRecords(m, m->ResourceRecords);
			}

		SetSPSProxyListChanged(mDNSNULL);		// Perform any deferred BPF reconfiguration now

		// Clear AnnounceOwner if necessary. (Do this *before* SendQueries() and SendResponses().)
		if (m->AnnounceOwner && m->timenow - m->AnnounceOwner >= 0) m->AnnounceOwner = 0;

		if (m->DelaySleep && m->timenow - m->DelaySleep >= 0)
			{
			m->DelaySleep = 0;
			if (m->SleepState == SleepState_Transferring)
				{
				LogSPS("Re-sleep delay passed; now checking for Sleep Proxy Servers");
				BeginSleepProcessing(m);
				}
			}

		// 4. See if we can answer any of our new local questions from the cache
		for (i=0; m->NewQuestions && i<1000; i++)
			{
			if (m->NewQuestions->DelayAnswering && m->timenow - m->NewQuestions->DelayAnswering < 0) break;
			AnswerNewQuestion(m);
			}
		if (i >= 1000) LogMsg("mDNS_Execute: AnswerNewQuestion exceeded loop limit");

		// Make sure we deliver *all* local RMV events, and clear the corresponding rr->AnsweredLocalQ flags, *before*
		// we begin generating *any* new ADD events in the m->NewLocalOnlyQuestions and m->NewLocalRecords loops below.
		for (i=0; i<1000 && m->LocalRemoveEvents; i++)
			{
			m->LocalRemoveEvents = mDNSfalse;
			m->CurrentRecord = m->ResourceRecords;
			CheckRmvEventsForLocalRecords(m);
			// Walk the LocalOnly records and deliver the RMV events
			for (slot = 0; slot < AUTH_HASH_SLOTS; slot++)
				for (ag = m->rrauth.rrauth_hash[slot]; ag; ag = ag->next)
					{
					m->CurrentRecord = ag->members;
					if (m->CurrentRecord) CheckRmvEventsForLocalRecords(m);
					}
			}

		if (i >= 1000) LogMsg("mDNS_Execute: m->LocalRemoveEvents exceeded loop limit");

		for (i=0; m->NewLocalOnlyQuestions && i<1000; i++) AnswerNewLocalOnlyQuestion(m);
		if (i >= 1000) LogMsg("mDNS_Execute: AnswerNewLocalOnlyQuestion exceeded loop limit");

		head = tail = mDNSNULL;
		for (i=0; i<1000 && m->NewLocalRecords && m->NewLocalRecords != head; i++)
			{
			AuthRecord *rr = m->NewLocalRecords;
			m->NewLocalRecords = m->NewLocalRecords->next;
			if (LocalRecordReady(rr))
				{
				debugf("mDNS_Execute: Delivering Add event with LocalAuthRecord %s", ARDisplayString(m, rr));
				AnswerAllLocalQuestionsWithLocalAuthRecord(m, rr, mDNStrue);
				}
			else if (!rr->next)
				{
				// If we have just one record that is not ready, we don't have to unlink and
				// reinsert. As the NewLocalRecords will be NULL for this case, the loop will
				// terminate and set the NewLocalRecords to rr.
				debugf("mDNS_Execute: Just one LocalAuthRecord %s, breaking out of the loop early", ARDisplayString(m, rr));
				if (head != mDNSNULL || m->NewLocalRecords != mDNSNULL)
					LogMsg("mDNS_Execute: ERROR!!: head %p, NewLocalRecords %p", head, m->NewLocalRecords);

				head = rr;
				}
			else
				{
				AuthRecord **p = &m->ResourceRecords;	// Find this record in our list of active records
				debugf("mDNS_Execute: Skipping LocalAuthRecord %s", ARDisplayString(m, rr));
				// if this is the first record we are skipping, move to the end of the list.
				// if we have already skipped records before, append it at the end.
				while (*p && *p != rr) p=&(*p)->next;
				if (*p) *p = rr->next;					// Cut this record from the list
				else { LogMsg("mDNS_Execute: ERROR!! Cannot find record %s in ResourceRecords list", ARDisplayString(m, rr)); break; }
				if (!head)
					{
					while (*p) p=&(*p)->next;
					*p = rr;
					head = tail = rr;
					}
				else
					{
					tail->next = rr;
					tail = rr;
					}
				rr->next = mDNSNULL;
				}
			}
		m->NewLocalRecords = head;
		debugf("mDNS_Execute: Setting NewLocalRecords to %s", (head ? ARDisplayString(m, head) : "NULL"));

		if (i >= 1000) LogMsg("mDNS_Execute: m->NewLocalRecords exceeded loop limit");

		// Check to see if we have any new LocalOnly/P2P records to examine for delivering
		// to our local questions
		if (m->NewLocalOnlyRecords)
			{
			m->NewLocalOnlyRecords = mDNSfalse;
			for (slot = 0; slot < AUTH_HASH_SLOTS; slot++)
				for (ag = m->rrauth.rrauth_hash[slot]; ag; ag = ag->next)
					{
					for (i=0; i<100 && ag->NewLocalOnlyRecords; i++)
						{
						AuthRecord *rr = ag->NewLocalOnlyRecords;
						ag->NewLocalOnlyRecords = ag->NewLocalOnlyRecords->next;
						// LocalOnly records should always be ready as they never probe
						if (LocalRecordReady(rr))
							{
							debugf("mDNS_Execute: Delivering Add event with LocalAuthRecord %s", ARDisplayString(m, rr));
							AnswerAllLocalQuestionsWithLocalAuthRecord(m, rr, mDNStrue);
							}
						else LogMsg("mDNS_Execute: LocalOnlyRecord %s not ready", ARDisplayString(m, rr));
						}
					// We limit about 100 per AuthGroup that can be serviced at a time
					if (i >= 100) LogMsg("mDNS_Execute: ag->NewLocalOnlyRecords exceeded loop limit");
					}
			}

		// 5. Some questions may have picked a new DNS server and the cache may answer these questions now.
		AnswerQuestionsForDNSServerChanges(m);

		// 6. See what packets we need to send
		if (m->mDNSPlatformStatus != mStatus_NoError || (m->SleepState == SleepState_Sleeping))
			DiscardDeregistrations(m);
		if (m->mDNSPlatformStatus == mStatus_NoError && (m->SuppressSending == 0 || m->timenow - m->SuppressSending >= 0))
			{
			// If the platform code is ready, and we're not suppressing packet generation right now
			// then send our responses, probes, and questions.
			// We check the cache first, because there might be records close to expiring that trigger questions to refresh them.
			// We send queries next, because there might be final-stage probes that complete their probing here, causing
			// them to advance to announcing state, and we want those to be included in any announcements we send out.
			// Finally, we send responses, including the previously mentioned records that just completed probing.
			m->SuppressSending = 0;

			// 7. Send Query packets. This may cause some probing records to advance to announcing state
			if (m->timenow - m->NextScheduledQuery >= 0 || m->timenow - m->NextScheduledProbe >= 0) SendQueries(m);
			if (m->timenow - m->NextScheduledQuery >= 0)
				{
				DNSQuestion *q;
				LogMsg("mDNS_Execute: SendQueries didn't send all its queries (%d - %d = %d) will try again in one second",
					m->timenow, m->NextScheduledQuery, m->timenow - m->NextScheduledQuery);
				m->NextScheduledQuery = m->timenow + mDNSPlatformOneSecond;
				for (q = m->Questions; q && q != m->NewQuestions; q=q->next)
					if (ActiveQuestion(q) && m->timenow - NextQSendTime(q) >= 0)
						LogMsg("mDNS_Execute: SendQueries didn't send %##s (%s)", q->qname.c, DNSTypeName(q->qtype));
				}
			if (m->timenow - m->NextScheduledProbe >= 0)
				{
				LogMsg("mDNS_Execute: SendQueries didn't send all its probes (%d - %d = %d) will try again in one second",
					m->timenow, m->NextScheduledProbe, m->timenow - m->NextScheduledProbe);
				m->NextScheduledProbe = m->timenow + mDNSPlatformOneSecond;
				}

			// 8. Send Response packets, including probing records just advanced to announcing state
			if (m->timenow - m->NextScheduledResponse >= 0) SendResponses(m);
			if (m->timenow - m->NextScheduledResponse >= 0)
				{
				LogMsg("mDNS_Execute: SendResponses didn't send all its responses; will try again in one second");
				m->NextScheduledResponse = m->timenow + mDNSPlatformOneSecond;
				}
			}

		// Clear RandomDelay values, ready to pick a new different value next time
		m->RandomQueryDelay     = 0;
		m->RandomReconfirmDelay = 0;

		if (m->NextScheduledStopTime && m->timenow - m->NextScheduledStopTime >= 0) TimeoutQuestions(m);
#ifndef UNICAST_DISABLED
		if (m->NextSRVUpdate && m->timenow - m->NextSRVUpdate >= 0) UpdateAllSRVRecords(m);
		if (m->timenow - m->NextScheduledNATOp >= 0) CheckNATMappings(m);
		if (m->timenow - m->NextuDNSEvent >= 0) uDNS_Tasks(m);
#endif
		}

	// Note about multi-threaded systems:
	// On a multi-threaded system, some other thread could run right after the mDNS_Unlock(),
	// performing mDNS API operations that change our next scheduled event time.
	//
	// On multi-threaded systems (like the current Windows implementation) that have a single main thread
	// calling mDNS_Execute() (and other threads allowed to call mDNS API routines) it is the responsibility
	// of the mDNSPlatformUnlock() routine to signal some kind of stateful condition variable that will
	// signal whatever blocking primitive the main thread is using, so that it will wake up and execute one
	// more iteration of its loop, and immediately call mDNS_Execute() again. The signal has to be stateful
	// in the sense that if the main thread has not yet entered its blocking primitive, then as soon as it
	// does, the state of the signal will be noticed, causing the blocking primitive to return immediately
	// without blocking. This avoids the race condition between the signal from the other thread arriving
	// just *before* or just *after* the main thread enters the blocking primitive.
	//
	// On multi-threaded systems (like the current Mac OS 9 implementation) that are entirely timer-driven,
	// with no main mDNS_Execute() thread, it is the responsibility of the mDNSPlatformUnlock() routine to
	// set the timer according to the m->NextScheduledEvent value, and then when the timer fires, the timer
	// callback function should call mDNS_Execute() (and ignore the return value, which may already be stale
	// by the time it gets to the timer callback function).

	mDNS_Unlock(m);		// Calling mDNS_Unlock is what gives m->NextScheduledEvent its new value
	return(m->NextScheduledEvent);
	}

mDNSlocal void SuspendLLQs(mDNS *m)
	{
	DNSQuestion *q;
	for (q = m->Questions; q; q = q->next)
		if (ActiveQuestion(q) && !mDNSOpaque16IsZero(q->TargetQID) && q->LongLived && q->state == LLQ_Established)
			{ q->ReqLease = 0; sendLLQRefresh(m, q); }
	}

mDNSlocal mDNSBool QuestionHasLocalAnswers(mDNS *const m, DNSQuestion *q)
	{
	AuthRecord *rr;
	mDNSu32 slot;
	AuthGroup *ag;

	slot = AuthHashSlot(&q->qname);
	ag = AuthGroupForName(&m->rrauth, slot, q->qnamehash, &q->qname);
	if (ag)
		{
		for (rr = ag->members; rr; rr=rr->next)
			// Filter the /etc/hosts records - LocalOnly, Unique, A/AAAA/CNAME
			if (LORecordAnswersAddressType(rr) && LocalOnlyRecordAnswersQuestion(rr, q))
				{
				LogInfo("QuestionHasLocalAnswers: Question %p %##s (%s) has local answer %s", q, q->qname.c, DNSTypeName(q->qtype), ARDisplayString(m, rr));
				return mDNStrue;
				}
		}
	return mDNSfalse;
	}

// ActivateUnicastQuery() is called from three places:
// 1. When a new question is created
// 2. On wake from sleep
// 3. When the DNS configuration changes
// In case 1 we don't want to mess with our established ThisQInterval and LastQTime (ScheduleImmediately is false)
// In cases 2 and 3 we do want to cause the question to be resent immediately (ScheduleImmediately is true)
mDNSlocal void ActivateUnicastQuery(mDNS *const m, DNSQuestion *const question, mDNSBool ScheduleImmediately)
	{
	// For now this AutoTunnel stuff is specific to Mac OS X.
	// In the future, if there's demand, we may see if we can abstract it out cleanly into the platform layer
#if APPLE_OSX_mDNSResponder
	// Even though BTMM client tunnels are only useful for AAAA queries, we need to treat v4 and v6 queries equally.
	// Otherwise we can get the situation where the A query completes really fast (with an NXDOMAIN result) and the
	// caller then gives up waiting for the AAAA result while we're still in the process of setting up the tunnel.
	// To level the playing field, we block both A and AAAA queries while tunnel setup is in progress, and then
	// returns results for both at the same time. If we are looking for the _autotunnel6 record, then skip this logic
	// as this would trigger looking up _autotunnel6._autotunnel6 and end up failing the original query.

	if (RRTypeIsAddressType(question->qtype) && PrivateQuery(question) &&
		!SameDomainLabel(question->qname.c, (const mDNSu8 *)"\x0c_autotunnel6")&& question->QuestionCallback != AutoTunnelCallback)
		{
		question->NoAnswer = NoAnswer_Suspended;
		AddNewClientTunnel(m, question);
		return;
		}
#endif // APPLE_OSX_mDNSResponder

	if (!question->DuplicateOf)
		{
		debugf("ActivateUnicastQuery: %##s %s%s%s",
			question->qname.c, DNSTypeName(question->qtype), PrivateQuery(question) ? " (Private)" : "", ScheduleImmediately ? " ScheduleImmediately" : "");
		question->CNAMEReferrals = 0;
		if (question->nta) { CancelGetZoneData(m, question->nta); question->nta = mDNSNULL; }
		if (question->LongLived)
			{
			question->state = LLQ_InitialRequest;
			question->id = zeroOpaque64;
			question->servPort = zeroIPPort;
			if (question->tcp) { DisposeTCPConn(question->tcp); question->tcp = mDNSNULL; }
			}
		// If the question has local answers, then we don't want answers from outside
		if (ScheduleImmediately && !QuestionHasLocalAnswers(m, question))
			{
			question->ThisQInterval = InitialQuestionInterval;
			question->LastQTime     = m->timenow - question->ThisQInterval;
			SetNextQueryTime(m, question);
			}
		}
	}

// Caller should hold the lock
mDNSexport void mDNSCoreRestartAddressQueries(mDNS *const m, mDNSBool SearchDomainsChanged, FlushCache flushCacheRecords,
	CallbackBeforeStartQuery BeforeStartCallback, void *context)
	{
	DNSQuestion *q;
	DNSQuestion *restart = mDNSNULL;

	if (!m->mDNS_busy) LogMsg("mDNSCoreRestartAddressQueries: ERROR!! Lock not held");

	// 1. Flush the cache records
	if (flushCacheRecords) flushCacheRecords(m);

	// 2. Even though we may have purged the cache records above, before it can generate RMV event
	// we are going to stop the question. Hence we need to deliver the RMV event before we
	// stop the question.
	//
	// CurrentQuestion is used by RmvEventsForQuestion below. While delivering RMV events, the
	// application callback can potentially stop the current question (detected by CurrentQuestion) or
	// *any* other question which could be the next one that we may process here. RestartQuestion
	// points to the "next" question which will be automatically advanced in mDNS_StopQuery_internal
	// if the "next" question is stopped while the CurrentQuestion is stopped

	if (m->RestartQuestion)
		LogMsg("mDNSCoreRestartAddressQueries: ERROR!! m->RestartQuestion already set: %##s (%s)",
			m->RestartQuestion->qname.c, DNSTypeName(m->RestartQuestion->qtype));

	m->RestartQuestion = m->Questions;
	while (m->RestartQuestion)
		{
		q = m->RestartQuestion;
		m->RestartQuestion = q->next;
		// GetZoneData questions are referenced by other questions (original query that started the GetZoneData
		// question)  through their "nta" pointer. Normally when the original query stops, it stops the
		// GetZoneData question and also frees the memory (See CancelGetZoneData). If we stop the GetZoneData
		// question followed by the original query that refers to this GetZoneData question, we will end up
		// freeing the GetZoneData question and then start the "freed" question at the end.

		if (IsGetZoneDataQuestion(q))
			{
			DNSQuestion *refq = q->next;
			LogInfo("mDNSCoreRestartAddressQueries: Skipping GetZoneDataQuestion %p %##s (%s)", q, q->qname.c, DNSTypeName(q->qtype));
			// debug stuff, we just try to find the referencing question and don't do much with it
			while (refq)
				{
				if (q == &refq->nta->question)
					{
					LogInfo("mDNSCoreRestartAddressQueries: Question %p %##s (%s) referring to GetZoneDataQuestion %p, not stopping", refq, refq->qname.c, DNSTypeName(refq->qtype), q);
					}
				refq = refq->next;
				}
			continue;
			}

		// This function is called when /etc/hosts changes and that could affect A, AAAA and CNAME queries
		if (q->qtype != kDNSType_A && q->qtype != kDNSType_AAAA && q->qtype != kDNSType_CNAME) continue;

		// If the search domains did not change, then we restart all the queries. Otherwise, only
		// for queries for which we "might" have appended search domains ("might" because we may
		// find results before we apply search domains even though AppendSearchDomains is set to 1)
		if (!SearchDomainsChanged || q->AppendSearchDomains)
			{
			// NOTE: CacheRecordRmvEventsForQuestion will not generate RMV events for queries that have non-zero
			// LOAddressAnswers. Hence it is important that we call CacheRecordRmvEventsForQuestion before
			// LocalRecordRmvEventsForQuestion (which decrements LOAddressAnswers). Let us say that
			// /etc/hosts has an A Record for web.apple.com. Any queries for web.apple.com will be answered locally.
			// But this can't prevent a CNAME/AAAA query to not to be sent on the wire. When it is sent on the wire,
			// it could create cache entries. When we are restarting queries, we can't deliver the cache RMV events
			// for the original query using these cache entries as ADDs were never delivered using these cache
			// entries and hence this order is needed.

			// If the query is suppressed, the RMV events won't be delivered
			if (!CacheRecordRmvEventsForQuestion(m, q)) { LogInfo("mDNSCoreRestartAddressQueries: Question deleted while delivering Cache Record RMV events"); continue; }

			// SuppressQuery status does not affect questions that are answered using local records
			if (!LocalRecordRmvEventsForQuestion(m, q)) { LogInfo("mDNSCoreRestartAddressQueries: Question deleted while delivering Local Record RMV events"); continue; }

			LogInfo("mDNSCoreRestartAddressQueries: Stop question %p %##s (%s), AppendSearchDomains %d, qnameOrig %p", q,
				q->qname.c, DNSTypeName(q->qtype), q->AppendSearchDomains, q->qnameOrig);
			mDNS_StopQuery_internal(m, q);
			// Reset state so that it looks like it was in the beginning i.e it should look at /etc/hosts, cache
			// and then search domains should be appended. At the beginning, qnameOrig was NULL.
			if (q->qnameOrig)
				{
				LogInfo("mDNSCoreRestartAddressQueries: qnameOrig %##s", q->qnameOrig);
				AssignDomainName(&q->qname, q->qnameOrig);
				mDNSPlatformMemFree(q->qnameOrig);
				q->qnameOrig = mDNSNULL;
				q->RetryWithSearchDomains = ApplySearchDomainsFirst(q) ? 1 : 0;
				}
			q->SearchListIndex = 0;
			q->next = restart;
			restart = q;
			}
		}

	// 3. Callback before we start the query
	if (BeforeStartCallback) BeforeStartCallback(m, context);

	// 4. Restart all the stopped queries
	while (restart)
		{
		q = restart;
		restart = restart->next;
		q->next = mDNSNULL;
		LogInfo("mDNSCoreRestartAddressQueries: Start question %p %##s (%s)", q, q->qname.c, DNSTypeName(q->qtype));
		mDNS_StartQuery_internal(m, q);
		}
	}

mDNSexport void mDNSCoreRestartQueries(mDNS *const m)
	{
	DNSQuestion *q;

#ifndef UNICAST_DISABLED
	// Retrigger all our uDNS questions
	if (m->CurrentQuestion)
		LogMsg("mDNSCoreRestartQueries: ERROR m->CurrentQuestion already set: %##s (%s)",
			m->CurrentQuestion->qname.c, DNSTypeName(m->CurrentQuestion->qtype));
	m->CurrentQuestion = m->Questions;
	while (m->CurrentQuestion)
		{
		q = m->CurrentQuestion;
		m->CurrentQuestion = m->CurrentQuestion->next;
		if (!mDNSOpaque16IsZero(q->TargetQID) && ActiveQuestion(q)) ActivateUnicastQuery(m, q, mDNStrue);
		}
#endif

	// Retrigger all our mDNS questions
	for (q = m->Questions; q; q=q->next)				// Scan our list of questions
		if (mDNSOpaque16IsZero(q->TargetQID) && ActiveQuestion(q))
			{
			q->ThisQInterval    = InitialQuestionInterval;	// MUST be > zero for an active question
			q->RequestUnicast   = 2;						// Set to 2 because is decremented once *before* we check it
			q->LastQTime        = m->timenow - q->ThisQInterval;
			q->RecentAnswerPkts = 0;
			ExpireDupSuppressInfo(q->DupSuppress, m->timenow);
			m->NextScheduledQuery = m->timenow;
			}
	}

// ***************************************************************************
#if COMPILER_LIKES_PRAGMA_MARK
#pragma mark -
#pragma mark - Power Management (Sleep/Wake)
#endif

mDNSexport void mDNS_UpdateAllowSleep(mDNS *const m)
	{
#ifndef IDLESLEEPCONTROL_DISABLED
	mDNSBool allowSleep = mDNStrue;
	char     reason[128];

	reason[0] = 0;

	if (m->SystemSleepOnlyIfWakeOnLAN)
		{
		// Don't sleep if we are a proxy for any services
		if (m->ProxyRecords)
			{
			allowSleep = mDNSfalse;
			mDNS_snprintf(reason, sizeof(reason), "sleep proxy for %d records", m->ProxyRecords);
			LogInfo("Sleep disabled because we are proxying %d records", m->ProxyRecords);
			}

		if (allowSleep && mDNSCoreHaveAdvertisedMulticastServices(m))
			{
			// Scan the list of active interfaces
			NetworkInterfaceInfo *intf;
			for (intf = GetFirstActiveInterface(m->HostInterfaces); intf; intf = GetFirstActiveInterface(intf->next))
				{
				if (intf->McastTxRx && !intf->Loopback)
					{
					// Disallow sleep if this interface doesn't support NetWake
					if (!intf->NetWake)
						{
						allowSleep = mDNSfalse;
						mDNS_snprintf(reason, sizeof(reason), "%s does not support NetWake", intf->ifname);
						LogInfo("Sleep disabled because %s does not support NetWake", intf->ifname);
						break;
						}

					// Disallow sleep if there is no sleep proxy server
					if (FindSPSInCache1(m, &intf->NetWakeBrowse, mDNSNULL, mDNSNULL) == mDNSNULL)
						{
						allowSleep = mDNSfalse;
						mDNS_snprintf(reason, sizeof(reason), "%s does not support NetWake", intf->ifname);
						LogInfo("Sleep disabled because %s has no sleep proxy", intf->ifname);
						break;
						}
					}
				}
			}
		}

	// Call the platform code to enable/disable sleep
	mDNSPlatformSetAllowSleep(m, allowSleep, reason);
#endif /* !defined(IDLESLEEPCONTROL_DISABLED) */
	}

mDNSlocal void SendSPSRegistrationForOwner(mDNS *const m, NetworkInterfaceInfo *const intf, const mDNSOpaque16 id, const OwnerOptData *const owner)
	{
	const int optspace = DNSOpt_Header_Space + DNSOpt_LeaseData_Space + DNSOpt_Owner_Space(&m->PrimaryMAC, &intf->MAC);
	const int sps = intf->NextSPSAttempt / 3;
	AuthRecord *rr;

	if (!intf->SPSAddr[sps].type)
		{
		intf->NextSPSAttemptTime = m->timenow + mDNSPlatformOneSecond;
		if (m->NextScheduledSPRetry - intf->NextSPSAttemptTime > 0)
			m->NextScheduledSPRetry = intf->NextSPSAttemptTime;
		LogSPS("SendSPSRegistration: %s SPS %d (%d) %##s not yet resolved", intf->ifname, intf->NextSPSAttempt, sps, intf->NetWakeResolve[sps].qname.c);
		goto exit;
		}

	// Mark our mDNS records (not unicast records) for transfer to SPS
	if (mDNSOpaque16IsZero(id))
		for (rr = m->ResourceRecords; rr; rr=rr->next)
			if (rr->resrec.RecordType > kDNSRecordTypeDeregistering)
				if (rr->resrec.InterfaceID == intf->InterfaceID || (!rr->resrec.InterfaceID && (rr->ForceMCast || IsLocalDomain(rr->resrec.name))))
					if (mDNSPlatformMemSame(owner, &rr->WakeUp, sizeof(*owner)))
						rr->SendRNow = mDNSInterfaceMark;	// mark it now

	while (1)
		{
		mDNSu8 *p = m->omsg.data;
		// To comply with RFC 2782, PutResourceRecord suppresses name compression for SRV records in unicast updates.
		// For now we follow that same logic for SPS registrations too.
		// If we decide to compress SRV records in SPS registrations in the future, we can achieve that by creating our
		// initial DNSMessage with h.flags set to zero, and then update it to UpdateReqFlags right before sending the packet.
		InitializeDNSMessage(&m->omsg.h, mDNSOpaque16IsZero(id) ? mDNS_NewMessageID(m) : id, UpdateReqFlags);

		for (rr = m->ResourceRecords; rr; rr=rr->next)
			if (rr->SendRNow || (!mDNSOpaque16IsZero(id) && !AuthRecord_uDNS(rr) && mDNSSameOpaque16(rr->updateid, id) && m->timenow - (rr->LastAPTime + rr->ThisAPInterval) >= 0))
				if (mDNSPlatformMemSame(owner, &rr->WakeUp, sizeof(*owner)))
					{
					mDNSu8 *newptr;
					const mDNSu8 *const limit = m->omsg.data + (m->omsg.h.mDNS_numUpdates ? NormalMaxDNSMessageData : AbsoluteMaxDNSMessageData) - optspace;
					if (rr->resrec.RecordType & kDNSRecordTypeUniqueMask)
						rr->resrec.rrclass |= kDNSClass_UniqueRRSet;	// Temporarily set the 'unique' bit so PutResourceRecord will set it
					newptr = PutResourceRecordTTLWithLimit(&m->omsg, p, &m->omsg.h.mDNS_numUpdates, &rr->resrec, rr->resrec.rroriginalttl, limit);
					rr->resrec.rrclass &= ~kDNSClass_UniqueRRSet;		// Make sure to clear 'unique' bit back to normal state
					if (!newptr)
						LogSPS("SendSPSRegistration put %s FAILED %d/%d %s", intf->ifname, p - m->omsg.data, limit - m->omsg.data, ARDisplayString(m, rr));
					else
						{
						LogSPS("SendSPSRegistration put %s %s", intf->ifname, ARDisplayString(m, rr));
						rr->SendRNow       = mDNSNULL;
						rr->ThisAPInterval = mDNSPlatformOneSecond;
						rr->LastAPTime     = m->timenow;
						rr->updateid       = m->omsg.h.id;
						if (m->NextScheduledResponse - (rr->LastAPTime + rr->ThisAPInterval) >= 0)
							m->NextScheduledResponse = (rr->LastAPTime + rr->ThisAPInterval);
						p = newptr;
						}
					}

		if (!m->omsg.h.mDNS_numUpdates) break;
		else
			{
			AuthRecord opt;
			mDNS_SetupResourceRecord(&opt, mDNSNULL, mDNSInterface_Any, kDNSType_OPT, kStandardTTL, kDNSRecordTypeKnownUnique, AuthRecordAny, mDNSNULL, mDNSNULL);
			opt.resrec.rrclass    = NormalMaxDNSMessageData;
			opt.resrec.rdlength   = sizeof(rdataOPT) * 2;	// Two options in this OPT record
			opt.resrec.rdestimate = sizeof(rdataOPT) * 2;
			opt.resrec.rdata->u.opt[0].opt           = kDNSOpt_Lease;
			opt.resrec.rdata->u.opt[0].optlen        = DNSOpt_LeaseData_Space - 4;
			opt.resrec.rdata->u.opt[0].u.updatelease = DEFAULT_UPDATE_LEASE;
			if (!owner->HMAC.l[0])											// If no owner data,
				SetupOwnerOpt(m, intf, &opt.resrec.rdata->u.opt[1]);		// use our own interface information
			else															// otherwise, use the owner data we were given
				{
				opt.resrec.rdata->u.opt[1].u.owner = *owner;
				opt.resrec.rdata->u.opt[1].opt     = kDNSOpt_Owner;
				opt.resrec.rdata->u.opt[1].optlen  = DNSOpt_Owner_Space(&owner->HMAC, &owner->IMAC) - 4;
				}
			LogSPS("SendSPSRegistration put %s %s", intf->ifname, ARDisplayString(m, &opt));
			p = PutResourceRecordTTLWithLimit(&m->omsg, p, &m->omsg.h.numAdditionals, &opt.resrec, opt.resrec.rroriginalttl, m->omsg.data + AbsoluteMaxDNSMessageData);
			if (!p)
				LogMsg("SendSPSRegistration: Failed to put OPT record (%d updates) %s", m->omsg.h.mDNS_numUpdates, ARDisplayString(m, &opt));
			else
				{
				mStatus err;

				LogSPS("SendSPSRegistration: Sending Update %s %d (%d) id %5d with %d records %d bytes to %#a:%d", intf->ifname, intf->NextSPSAttempt, sps,
					mDNSVal16(m->omsg.h.id), m->omsg.h.mDNS_numUpdates, p - m->omsg.data, &intf->SPSAddr[sps], mDNSVal16(intf->SPSPort[sps]));
				// if (intf->NextSPSAttempt < 5) m->omsg.h.flags = zeroID;	// For simulating packet loss
				err = mDNSSendDNSMessage(m, &m->omsg, p, intf->InterfaceID, mDNSNULL, &intf->SPSAddr[sps], intf->SPSPort[sps], mDNSNULL, mDNSNULL);
				if (err) LogSPS("SendSPSRegistration: mDNSSendDNSMessage err %d", err);
				if (err && intf->SPSAddr[sps].type == mDNSAddrType_IPv6 && intf->NetWakeResolve[sps].ThisQInterval == -1)
					{
					LogSPS("SendSPSRegistration %d %##s failed to send to IPv6 address; will try IPv4 instead", sps, intf->NetWakeResolve[sps].qname.c);
					intf->NetWakeResolve[sps].qtype = kDNSType_A;
					mDNS_StartQuery_internal(m, &intf->NetWakeResolve[sps]);
					return;
					}
				}
			}
		}

	intf->NextSPSAttemptTime = m->timenow + mDNSPlatformOneSecond * 10;		// If successful, update NextSPSAttemptTime

exit:
	if (mDNSOpaque16IsZero(id) && intf->NextSPSAttempt < 8) intf->NextSPSAttempt++;
	}

mDNSlocal mDNSBool RecordIsFirstOccurrenceOfOwner(mDNS *const m, const AuthRecord *const rr)
	{
	AuthRecord *ar;
	for (ar = m->ResourceRecords; ar && ar != rr; ar=ar->next)
		if (mDNSPlatformMemSame(&rr->WakeUp, &ar->WakeUp, sizeof(rr->WakeUp))) return mDNSfalse;
	return mDNStrue;
	}

mDNSlocal void SendSPSRegistration(mDNS *const m, NetworkInterfaceInfo *const intf, const mDNSOpaque16 id)
	{
	AuthRecord *ar;
	OwnerOptData owner = zeroOwner;

	SendSPSRegistrationForOwner(m, intf, id, &owner);

	for (ar = m->ResourceRecords; ar; ar=ar->next)
		{
		if (!mDNSPlatformMemSame(&owner, &ar->WakeUp, sizeof(owner)) && RecordIsFirstOccurrenceOfOwner(m, ar))
			{
			owner = ar->WakeUp;
			SendSPSRegistrationForOwner(m, intf, id, &owner);
			}
		}
	}

// RetrySPSRegistrations is called from SendResponses, with the lock held
mDNSlocal void RetrySPSRegistrations(mDNS *const m)
	{
	AuthRecord *rr;
	NetworkInterfaceInfo *intf;

	// First make sure none of our interfaces' NextSPSAttemptTimes are inadvertently set to m->timenow + mDNSPlatformOneSecond * 10
	for (intf = GetFirstActiveInterface(m->HostInterfaces); intf; intf = GetFirstActiveInterface(intf->next))
		if (intf->NextSPSAttempt && intf->NextSPSAttemptTime == m->timenow + mDNSPlatformOneSecond * 10)
			intf->NextSPSAttemptTime++;

	// Retry any record registrations that are due
	for (rr = m->ResourceRecords; rr; rr=rr->next)
		if (!AuthRecord_uDNS(rr) && !mDNSOpaque16IsZero(rr->updateid) && m->timenow - (rr->LastAPTime + rr->ThisAPInterval) >= 0)
			for (intf = GetFirstActiveInterface(m->HostInterfaces); intf; intf = GetFirstActiveInterface(intf->next))
				if (!rr->resrec.InterfaceID || rr->resrec.InterfaceID == intf->InterfaceID)
					{
					LogSPS("RetrySPSRegistrations: %s", ARDisplayString(m, rr));
					SendSPSRegistration(m, intf, rr->updateid);
					}

	// For interfaces where we did an SPS registration attempt, increment intf->NextSPSAttempt
	for (intf = GetFirstActiveInterface(m->HostInterfaces); intf; intf = GetFirstActiveInterface(intf->next))
		if (intf->NextSPSAttempt && intf->NextSPSAttemptTime == m->timenow + mDNSPlatformOneSecond * 10 && intf->NextSPSAttempt < 8)
			intf->NextSPSAttempt++;
	}

mDNSlocal void NetWakeResolve(mDNS *const m, DNSQuestion *question, const ResourceRecord *const answer, QC_result AddRecord)
	{
	NetworkInterfaceInfo *intf = (NetworkInterfaceInfo *)question->QuestionContext;
	int sps = (int)(question - intf->NetWakeResolve);
	(void)m;			// Unused
	LogSPS("NetWakeResolve: SPS: %d Add: %d %s", sps, AddRecord, RRDisplayString(m, answer));

	if (!AddRecord) return;												// Don't care about REMOVE events
	if (answer->rrtype != question->qtype) return;						// Don't care about CNAMEs

	// if (answer->rrtype == kDNSType_AAAA && sps == 0) return;	// To test failing to resolve sleep proxy's address

	if (answer->rrtype == kDNSType_SRV)
		{
		// 1. Got the SRV record; now look up the target host's IPv6 link-local address
		mDNS_StopQuery(m, question);
		intf->SPSPort[sps] = answer->rdata->u.srv.port;
		AssignDomainName(&question->qname, &answer->rdata->u.srv.target);
		question->qtype = kDNSType_AAAA;
		mDNS_StartQuery(m, question);
		}
	else if (answer->rrtype == kDNSType_AAAA && answer->rdlength == sizeof(mDNSv6Addr) && mDNSv6AddressIsLinkLocal(&answer->rdata->u.ipv6))
		{
		// 2. Got the target host's IPv6 link-local address; record address and initiate an SPS registration if appropriate
		mDNS_StopQuery(m, question);
		question->ThisQInterval = -1;
		intf->SPSAddr[sps].type = mDNSAddrType_IPv6;
		intf->SPSAddr[sps].ip.v6 = answer->rdata->u.ipv6;
		mDNS_Lock(m);
		if (sps == intf->NextSPSAttempt/3) SendSPSRegistration(m, intf, zeroID);	// If we're ready for this result, use it now
		mDNS_Unlock(m);
		}
	else if (answer->rrtype == kDNSType_AAAA && answer->rdlength == 0)
		{
		// 3. Got negative response -- target host apparently has IPv6 disabled -- so try looking up the target host's IPv4 address(es) instead
		mDNS_StopQuery(m, question);
		LogSPS("NetWakeResolve: SPS %d %##s has no IPv6 address, will try IPv4 instead", sps, question->qname.c);
		question->qtype = kDNSType_A;
		mDNS_StartQuery(m, question);
		}
	else if (answer->rrtype == kDNSType_A && answer->rdlength == sizeof(mDNSv4Addr))
		{
		// 4. Got an IPv4 address for the target host; record address and initiate an SPS registration if appropriate
		mDNS_StopQuery(m, question);
		question->ThisQInterval = -1;
		intf->SPSAddr[sps].type = mDNSAddrType_IPv4;
		intf->SPSAddr[sps].ip.v4 = answer->rdata->u.ipv4;
		mDNS_Lock(m);
		if (sps == intf->NextSPSAttempt/3) SendSPSRegistration(m, intf, zeroID);	// If we're ready for this result, use it now
		mDNS_Unlock(m);
		}
	}

mDNSexport mDNSBool mDNSCoreHaveAdvertisedMulticastServices(mDNS *const m)
	{
	AuthRecord *rr;
	for (rr = m->ResourceRecords; rr; rr=rr->next)
		if (rr->resrec.rrtype == kDNSType_SRV && !AuthRecord_uDNS(rr) && !mDNSSameIPPort(rr->resrec.rdata->u.srv.port, DiscardPort))
			return mDNStrue;
	return mDNSfalse;
	}

mDNSlocal void SendSleepGoodbyes(mDNS *const m)
	{
	AuthRecord *rr;
	m->SleepState = SleepState_Sleeping;

#ifndef UNICAST_DISABLED
	SleepRecordRegistrations(m);	// If we have no SPS, need to deregister our uDNS records
#endif /* UNICAST_DISABLED */

	// Mark all the records we need to deregister and send them
	for (rr = m->ResourceRecords; rr; rr=rr->next)
		if (rr->resrec.RecordType == kDNSRecordTypeShared && rr->RequireGoodbye)
			rr->ImmedAnswer = mDNSInterfaceMark;
	SendResponses(m);
	}

// BeginSleepProcessing is called, with the lock held, from either mDNS_Execute or mDNSCoreMachineSleep
mDNSlocal void BeginSleepProcessing(mDNS *const m)
	{
	mDNSBool SendGoodbyes = mDNStrue;
	const CacheRecord *sps[3] = { mDNSNULL };

	m->NextScheduledSPRetry = m->timenow;

	if      (!m->SystemWakeOnLANEnabled)                  LogSPS("BeginSleepProcessing: m->SystemWakeOnLANEnabled is false");
	else if (!mDNSCoreHaveAdvertisedMulticastServices(m)) LogSPS("BeginSleepProcessing: No advertised services");
	else	// If we have at least one advertised service
		{
		NetworkInterfaceInfo *intf;
		for (intf = GetFirstActiveInterface(m->HostInterfaces); intf; intf = GetFirstActiveInterface(intf->next))
			{
			if (!intf->NetWake) LogSPS("BeginSleepProcessing: %-6s not capable of magic packet wakeup", intf->ifname);
#if APPLE_OSX_mDNSResponder
			else if (ActivateLocalProxy(m, intf->ifname) == mStatus_NoError)
				{
				SendGoodbyes = mDNSfalse;
				LogSPS("BeginSleepProcessing: %-6s using local proxy", intf->ifname);
				// This will leave m->SleepState set to SleepState_Transferring,
				// which is okay because with no outstanding resolves, or updates in flight,
				// mDNSCoreReadyForSleep() will conclude correctly that all the updates have already completed
				}
#endif // APPLE_OSX_mDNSResponder
			else
				{
				FindSPSInCache(m, &intf->NetWakeBrowse, sps);
				if (!sps[0]) LogSPS("BeginSleepProcessing: %-6s %#a No Sleep Proxy Server found (Next Browse Q in %d, interval %d)",
					intf->ifname, &intf->ip, NextQSendTime(&intf->NetWakeBrowse) - m->timenow, intf->NetWakeBrowse.ThisQInterval);
				else
					{
					int i;
					SendGoodbyes = mDNSfalse;
					intf->NextSPSAttempt = 0;
					intf->NextSPSAttemptTime = m->timenow + mDNSPlatformOneSecond;
					// Don't need to set m->NextScheduledSPRetry here because we already set "m->NextScheduledSPRetry = m->timenow" above
					for (i=0; i<3; i++)
						{
#if ForceAlerts
						if (intf->SPSAddr[i].type)
							{ LogMsg("BeginSleepProcessing: %s %d intf->SPSAddr[i].type %d", intf->ifname, i, intf->SPSAddr[i].type); *(long*)0 = 0; }
						if (intf->NetWakeResolve[i].ThisQInterval >= 0)
							{ LogMsg("BeginSleepProcessing: %s %d intf->NetWakeResolve[i].ThisQInterval %d", intf->ifname, i, intf->NetWakeResolve[i].ThisQInterval); *(long*)0 = 0; }
#endif
						intf->SPSAddr[i].type = mDNSAddrType_None;
						if (intf->NetWakeResolve[i].ThisQInterval >= 0) mDNS_StopQuery(m, &intf->NetWakeResolve[i]);
						intf->NetWakeResolve[i].ThisQInterval = -1;
						if (sps[i])
							{
							LogSPS("BeginSleepProcessing: %-6s Found Sleep Proxy Server %d TTL %d %s", intf->ifname, i, sps[i]->resrec.rroriginalttl, CRDisplayString(m, sps[i]));
							mDNS_SetupQuestion(&intf->NetWakeResolve[i], in