1 /* -*- Mode: C; tab-width: 4 -*- 2 * 3 * Copyright (c) 2002-2006 Apple Computer, Inc. All rights reserved. 4 * 5 * Licensed under the Apache License, Version 2.0 (the "License"); 6 * you may not use this file except in compliance with the License. 7 * You may obtain a copy of the License at 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0 10 * 11 * Unless required by applicable law or agreed to in writing, software 12 * distributed under the License is distributed on an "AS IS" BASIS, 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 * See the License for the specific language governing permissions and 15 * limitations under the License. 16 * 17 * This code is completely 100% portable C. It does not depend on any external header files 18 * from outside the mDNS project -- all the types it expects to find are defined right here. 19 * 20 * The previous point is very important: This file does not depend on any external 21 * header files. It should compile on *any* platform that has a C compiler, without 22 * making *any* assumptions about availability of so-called "standard" C functions, 23 * routines, or types (which may or may not be present on any given platform). 24 25 * Formatting notes: 26 * This code follows the "Whitesmiths style" C indentation rules. Plenty of discussion 27 * on C indentation can be found on the web, such as <http://www.kafejo.com/komp/1tbs.htm>, 28 * but for the sake of brevity here I will say just this: Curly braces are not syntactially 29 * part of an "if" statement; they are the beginning and ending markers of a compound statement; 30 * therefore common sense dictates that if they are part of a compound statement then they 31 * should be indented to the same level as everything else in that compound statement. 32 * Indenting curly braces at the same level as the "if" implies that curly braces are 33 * part of the "if", which is false. (This is as misleading as people who write "char* x,y;" 34 * thinking that variables x and y are both of type "char*" -- and anyone who doesn't 35 * understand why variable y is not of type "char*" just proves the point that poor code 36 * layout leads people to unfortunate misunderstandings about how the C language really works.) 37 */ 38 39 #include "DNSCommon.h" // Defines general DNS untility routines 40 #include "uDNS.h" // Defines entry points into unicast-specific routines 41 42 // Disable certain benign warnings with Microsoft compilers 43 #if(defined(_MSC_VER)) 44 // Disable "conditional expression is constant" warning for debug macros. 45 // Otherwise, this generates warnings for the perfectly natural construct "while(1)" 46 // If someone knows a variant way of writing "while(1)" that doesn't generate warning messages, please let us know 47 #pragma warning(disable:4127) 48 49 // Disable "assignment within conditional expression". 50 // Other compilers understand the convention that if you place the assignment expression within an extra pair 51 // of parentheses, this signals to the compiler that you really intended an assignment and no warning is necessary. 52 // The Microsoft compiler doesn't understand this convention, so in the absense of any other way to signal 53 // to the compiler that the assignment is intentional, we have to just turn this warning off completely. 54 #pragma warning(disable:4706) 55 #endif 56 57 #if APPLE_OSX_mDNSResponder 58 59 #include <WebFilterDNS/WebFilterDNS.h> 60 61 #if ! NO_WCF 62 WCFConnection *WCFConnectionNew(void) __attribute__((weak_import)); 63 void WCFConnectionDealloc(WCFConnection* c) __attribute__((weak_import)); 64 65 // Do we really need to define a macro for "if"? 66 #define CHECK_WCF_FUNCTION(X) if (X) 67 #endif // ! NO_WCF 68 69 #else 70 71 #define NO_WCF 1 72 #endif // APPLE_OSX_mDNSResponder 73 74 // Forward declarations 75 mDNSlocal void BeginSleepProcessing(mDNS *const m); 76 mDNSlocal void RetrySPSRegistrations(mDNS *const m); 77 mDNSlocal void SendWakeup(mDNS *const m, mDNSInterfaceID InterfaceID, mDNSEthAddr *EthAddr, mDNSOpaque48 *password); 78 mDNSlocal mDNSBool CacheRecordRmvEventsForQuestion(mDNS *const m, DNSQuestion *q); 79 mDNSlocal mDNSBool LocalRecordRmvEventsForQuestion(mDNS *const m, DNSQuestion *q); 80 mDNSlocal void mDNS_PurgeBeforeResolve(mDNS *const m, DNSQuestion *q); 81 82 // *************************************************************************** 83 #if COMPILER_LIKES_PRAGMA_MARK 84 #pragma mark - Program Constants 85 #endif 86 87 #define NO_HINFO 1 88 89 90 // Any records bigger than this are considered 'large' records 91 #define SmallRecordLimit 1024 92 93 #define kMaxUpdateCredits 10 94 #define kUpdateCreditRefreshInterval (mDNSPlatformOneSecond * 6) 95 96 mDNSexport const char *const mDNS_DomainTypeNames[] = 97 { 98 "b._dns-sd._udp.", // Browse 99 "db._dns-sd._udp.", // Default Browse 100 "lb._dns-sd._udp.", // Automatic Browse 101 "r._dns-sd._udp.", // Registration 102 "dr._dns-sd._udp." // Default Registration 103 }; 104 105 #ifdef UNICAST_DISABLED 106 #define uDNS_IsActiveQuery(q, u) mDNSfalse 107 #endif 108 109 // *************************************************************************** 110 #if COMPILER_LIKES_PRAGMA_MARK 111 #pragma mark - 112 #pragma mark - General Utility Functions 113 #endif 114 115 // If there is a authoritative LocalOnly record that answers questions of type A, AAAA and CNAME 116 // this returns true. Main use is to handle /etc/hosts records. 117 #define LORecordAnswersAddressType(rr) ((rr)->ARType == AuthRecordLocalOnly && \ 118 (rr)->resrec.RecordType & kDNSRecordTypeUniqueMask && \ 119 ((rr)->resrec.rrtype == kDNSType_A || (rr)->resrec.rrtype == kDNSType_AAAA || \ 120 (rr)->resrec.rrtype == kDNSType_CNAME)) 121 122 #define FollowCNAME(q, rr, AddRecord) (AddRecord && (q)->qtype != kDNSType_CNAME && \ 123 (rr)->RecordType != kDNSRecordTypePacketNegative && \ 124 (rr)->rrtype == kDNSType_CNAME) 125 126 mDNSlocal void SetNextQueryStopTime(mDNS *const m, const DNSQuestion *const q) 127 { 128 if (m->mDNS_busy != m->mDNS_reentrancy+1) 129 LogMsg("SetNextQueryTime: Lock not held! mDNS_busy (%ld) mDNS_reentrancy (%ld)", m->mDNS_busy, m->mDNS_reentrancy); 130 131 #if ForceAlerts 132 if (m->mDNS_busy != m->mDNS_reentrancy+1) *(long*)0 = 0; 133 #endif 134 135 if (m->NextScheduledStopTime - q->StopTime > 0) 136 m->NextScheduledStopTime = q->StopTime; 137 } 138 139 mDNSexport void SetNextQueryTime(mDNS *const m, const DNSQuestion *const q) 140 { 141 if (m->mDNS_busy != m->mDNS_reentrancy+1) 142 LogMsg("SetNextQueryTime: Lock not held! mDNS_busy (%ld) mDNS_reentrancy (%ld)", m->mDNS_busy, m->mDNS_reentrancy); 143 144 #if ForceAlerts 145 if (m->mDNS_busy != m->mDNS_reentrancy+1) *(long*)0 = 0; 146 #endif 147 148 if (ActiveQuestion(q)) 149 { 150 // Depending on whether this is a multicast or unicast question we want to set either: 151 // m->NextScheduledQuery = NextQSendTime(q) or 152 // m->NextuDNSEvent = NextQSendTime(q) 153 mDNSs32 *const timer = mDNSOpaque16IsZero(q->TargetQID) ? &m->NextScheduledQuery : &m->NextuDNSEvent; 154 if (*timer - NextQSendTime(q) > 0) 155 *timer = NextQSendTime(q); 156 } 157 } 158 159 mDNSlocal void ReleaseAuthEntity(AuthHash *r, AuthEntity *e) 160 { 161 #if APPLE_OSX_mDNSResponder && MACOSX_MDNS_MALLOC_DEBUGGING >= 1 162 unsigned int i; 163 for (i=0; i<sizeof(*e); i++) ((char*)e)[i] = 0xFF; 164 #endif 165 e->next = r->rrauth_free; 166 r->rrauth_free = e; 167 r->rrauth_totalused--; 168 } 169 170 mDNSlocal void ReleaseAuthGroup(AuthHash *r, AuthGroup **cp) 171 { 172 AuthEntity *e = (AuthEntity *)(*cp); 173 LogMsg("ReleaseAuthGroup: Releasing AuthGroup %##s", (*cp)->name->c); 174 if ((*cp)->rrauth_tail != &(*cp)->members) 175 LogMsg("ERROR: (*cp)->members == mDNSNULL but (*cp)->rrauth_tail != &(*cp)->members)"); 176 if ((*cp)->name != (domainname*)((*cp)->namestorage)) mDNSPlatformMemFree((*cp)->name); 177 (*cp)->name = mDNSNULL; 178 *cp = (*cp)->next; // Cut record from list 179 ReleaseAuthEntity(r, e); 180 } 181 182 mDNSlocal AuthEntity *GetAuthEntity(AuthHash *r, const AuthGroup *const PreserveAG) 183 { 184 AuthEntity *e = mDNSNULL; 185 186 if (r->rrauth_lock) { LogMsg("GetFreeCacheRR ERROR! Cache already locked!"); return(mDNSNULL); } 187 r->rrauth_lock = 1; 188 189 if (!r->rrauth_free) 190 { 191 // We allocate just one AuthEntity at a time because we need to be able 192 // free them all individually which normally happens when we parse /etc/hosts into 193 // AuthHash where we add the "new" entries and discard (free) the already added 194 // entries. If we allocate as chunks, we can't free them individually. 195 AuthEntity *storage = mDNSPlatformMemAllocate(sizeof(AuthEntity)); 196 storage->next = mDNSNULL; 197 r->rrauth_free = storage; 198 } 199 200 // If we still have no free records, recycle all the records we can. 201 // Enumerating the entire auth is moderately expensive, so when we do it, we reclaim all the records we can in one pass. 202 if (!r->rrauth_free) 203 { 204 mDNSu32 oldtotalused = r->rrauth_totalused; 205 mDNSu32 slot; 206 for (slot = 0; slot < AUTH_HASH_SLOTS; slot++) 207 { 208 AuthGroup **cp = &r->rrauth_hash[slot]; 209 while (*cp) 210 { 211 if ((*cp)->members || (*cp)==PreserveAG) cp=&(*cp)->next; 212 else ReleaseAuthGroup(r, cp); 213 } 214 } 215 LogInfo("GetAuthEntity: Recycled %d records to reduce auth cache from %d to %d", 216 oldtotalused - r->rrauth_totalused, oldtotalused, r->rrauth_totalused); 217 } 218 219 if (r->rrauth_free) // If there are records in the free list, take one 220 { 221 e = r->rrauth_free; 222 r->rrauth_free = e->next; 223 if (++r->rrauth_totalused >= r->rrauth_report) 224 { 225 LogInfo("RR Auth now using %ld objects", r->rrauth_totalused); 226 if (r->rrauth_report < 100) r->rrauth_report += 10; 227 else if (r->rrauth_report < 1000) r->rrauth_report += 100; 228 else r->rrauth_report += 1000; 229 } 230 mDNSPlatformMemZero(e, sizeof(*e)); 231 } 232 233 r->rrauth_lock = 0; 234 235 return(e); 236 } 237 238 mDNSexport AuthGroup *AuthGroupForName(AuthHash *r, const mDNSu32 slot, const mDNSu32 namehash, const domainname *const name) 239 { 240 AuthGroup *ag; 241 for (ag = r->rrauth_hash[slot]; ag; ag=ag->next) 242 if (ag->namehash == namehash && SameDomainName(ag->name, name)) 243 break; 244 return(ag); 245 } 246 247 mDNSexport AuthGroup *AuthGroupForRecord(AuthHash *r, const mDNSu32 slot, const ResourceRecord *const rr) 248 { 249 return(AuthGroupForName(r, slot, rr->namehash, rr->name)); 250 } 251 252 mDNSlocal AuthGroup *GetAuthGroup(AuthHash *r, const mDNSu32 slot, const ResourceRecord *const rr) 253 { 254 mDNSu16 namelen = DomainNameLength(rr->name); 255 AuthGroup *ag = (AuthGroup*)GetAuthEntity(r, mDNSNULL); 256 if (!ag) { LogMsg("GetAuthGroup: Failed to allocate memory for %##s", rr->name->c); return(mDNSNULL); } 257 ag->next = r->rrauth_hash[slot]; 258 ag->namehash = rr->namehash; 259 ag->members = mDNSNULL; 260 ag->rrauth_tail = &ag->members; 261 ag->name = (domainname*)ag->namestorage; 262 ag->NewLocalOnlyRecords = mDNSNULL; 263 if (namelen > InlineCacheGroupNameSize) ag->name = mDNSPlatformMemAllocate(namelen); 264 if (!ag->name) 265 { 266 LogMsg("GetAuthGroup: Failed to allocate name storage for %##s", rr->name->c); 267 ReleaseAuthEntity(r, (AuthEntity*)ag); 268 return(mDNSNULL); 269 } 270 AssignDomainName(ag->name, rr->name); 271 272 if (AuthGroupForRecord(r, slot, rr)) LogMsg("GetAuthGroup: Already have AuthGroup for %##s", rr->name->c); 273 r->rrauth_hash[slot] = ag; 274 if (AuthGroupForRecord(r, slot, rr) != ag) LogMsg("GetAuthGroup: Not finding AuthGroup for %##s", rr->name->c); 275 276 return(ag); 277 } 278 279 // Returns the AuthGroup in which the AuthRecord was inserted 280 mDNSexport AuthGroup *InsertAuthRecord(mDNS *const m, AuthHash *r, AuthRecord *rr) 281 { 282 AuthGroup *ag; 283 const mDNSu32 slot = AuthHashSlot(rr->resrec.name); 284 ag = AuthGroupForRecord(r, slot, &rr->resrec); 285 if (!ag) ag = GetAuthGroup(r, slot, &rr->resrec); // If we don't have a AuthGroup for this name, make one now 286 if (ag) 287 { 288 LogInfo("InsertAuthRecord: inserting auth record %s from table", ARDisplayString(m, rr)); 289 *(ag->rrauth_tail) = rr; // Append this record to tail of cache slot list 290 ag->rrauth_tail = &(rr->next); // Advance tail pointer 291 } 292 return ag; 293 } 294 295 mDNSexport AuthGroup *RemoveAuthRecord(mDNS *const m, AuthHash *r, AuthRecord *rr) 296 { 297 AuthGroup *a; 298 AuthGroup **ag = &a; 299 AuthRecord **rp; 300 const mDNSu32 slot = AuthHashSlot(rr->resrec.name); 301 302 a = AuthGroupForRecord(r, slot, &rr->resrec); 303 if (!a) { LogMsg("RemoveAuthRecord: ERROR!! AuthGroup not found for %s", ARDisplayString(m, rr)); return mDNSNULL; } 304 rp = &(*ag)->members; 305 while (*rp) 306 { 307 if (*rp != rr) 308 rp=&(*rp)->next; 309 else 310 { 311 // We don't break here, so that we can set the tail below without tracking "prev" pointers 312 313 LogInfo("RemoveAuthRecord: removing auth record %s from table", ARDisplayString(m, rr)); 314 *rp = (*rp)->next; // Cut record from list 315 } 316 } 317 // TBD: If there are no more members, release authgroup ? 318 (*ag)->rrauth_tail = rp; 319 return a; 320 } 321 322 mDNSexport CacheGroup *CacheGroupForName(const mDNS *const m, const mDNSu32 slot, const mDNSu32 namehash, const domainname *const name) 323 { 324 CacheGroup *cg; 325 for (cg = m->rrcache_hash[slot]; cg; cg=cg->next) 326 if (cg->namehash == namehash && SameDomainName(cg->name, name)) 327 break; 328 return(cg); 329 } 330 331 mDNSlocal CacheGroup *CacheGroupForRecord(const mDNS *const m, const mDNSu32 slot, const ResourceRecord *const rr) 332 { 333 return(CacheGroupForName(m, slot, rr->namehash, rr->name)); 334 } 335 336 mDNSexport mDNSBool mDNS_AddressIsLocalSubnet(mDNS *const m, const mDNSInterfaceID InterfaceID, const mDNSAddr *addr) 337 { 338 NetworkInterfaceInfo *intf; 339 340 if (addr->type == mDNSAddrType_IPv4) 341 { 342 // Normally we resist touching the NotAnInteger fields, but here we're doing tricky bitwise masking so we make an exception 343 if (mDNSv4AddressIsLinkLocal(&addr->ip.v4)) return(mDNStrue); 344 for (intf = m->HostInterfaces; intf; intf = intf->next) 345 if (intf->ip.type == addr->type && intf->InterfaceID == InterfaceID && intf->McastTxRx) 346 if (((intf->ip.ip.v4.NotAnInteger ^ addr->ip.v4.NotAnInteger) & intf->mask.ip.v4.NotAnInteger) == 0) 347 return(mDNStrue); 348 } 349 350 if (addr->type == mDNSAddrType_IPv6) 351 { 352 if (mDNSv6AddressIsLinkLocal(&addr->ip.v6)) return(mDNStrue); 353 for (intf = m->HostInterfaces; intf; intf = intf->next) 354 if (intf->ip.type == addr->type && intf->InterfaceID == InterfaceID && intf->McastTxRx) 355 if ((((intf->ip.ip.v6.l[0] ^ addr->ip.v6.l[0]) & intf->mask.ip.v6.l[0]) == 0) && 356 (((intf->ip.ip.v6.l[1] ^ addr->ip.v6.l[1]) & intf->mask.ip.v6.l[1]) == 0) && 357 (((intf->ip.ip.v6.l[2] ^ addr->ip.v6.l[2]) & intf->mask.ip.v6.l[2]) == 0) && 358 (((intf->ip.ip.v6.l[3] ^ addr->ip.v6.l[3]) & intf->mask.ip.v6.l[3]) == 0)) 359 return(mDNStrue); 360 } 361 362 return(mDNSfalse); 363 } 364 365 mDNSlocal NetworkInterfaceInfo *FirstInterfaceForID(mDNS *const m, const mDNSInterfaceID InterfaceID) 366 { 367 NetworkInterfaceInfo *intf = m->HostInterfaces; 368 while (intf && intf->InterfaceID != InterfaceID) intf = intf->next; 369 return(intf); 370 } 371 372 mDNSexport char *InterfaceNameForID(mDNS *const m, const mDNSInterfaceID InterfaceID) 373 { 374 NetworkInterfaceInfo *intf = FirstInterfaceForID(m, InterfaceID); 375 return(intf ? intf->ifname : mDNSNULL); 376 } 377 378 // Caller should hold the lock 379 mDNSlocal void GenerateNegativeResponse(mDNS *const m) 380 { 381 DNSQuestion *q; 382 if (!m->CurrentQuestion) { LogMsg("GenerateNegativeResponse: ERROR!! CurrentQuestion not set"); return; } 383 q = m->CurrentQuestion; 384 LogInfo("GenerateNegativeResponse: Generating negative response for question %##s (%s)", q->qname.c, DNSTypeName(q->qtype)); 385 386 MakeNegativeCacheRecord(m, &m->rec.r, &q->qname, q->qnamehash, q->qtype, q->qclass, 60, mDNSInterface_Any, mDNSNULL); 387 AnswerCurrentQuestionWithResourceRecord(m, &m->rec.r, QC_addnocache); 388 if (m->CurrentQuestion == q) { q->ThisQInterval = 0; } // Deactivate this question 389 // Don't touch the question after this 390 m->rec.r.resrec.RecordType = 0; // Clear RecordType to show we're not still using it 391 } 392 393 mDNSlocal void AnswerQuestionByFollowingCNAME(mDNS *const m, DNSQuestion *q, ResourceRecord *rr) 394 { 395 const mDNSBool selfref = SameDomainName(&q->qname, &rr->rdata->u.name); 396 if (q->CNAMEReferrals >= 10 || selfref) 397 LogMsg("AnswerQuestionByFollowingCNAME: %p %##s (%s) NOT following CNAME referral %d%s for %s", 398 q, q->qname.c, DNSTypeName(q->qtype), q->CNAMEReferrals, selfref ? " (Self-Referential)" : "", RRDisplayString(m, rr)); 399 else 400 { 401 const mDNSu32 c = q->CNAMEReferrals + 1; // Stash a copy of the new q->CNAMEReferrals value 402 403 // The SameDomainName check above is to ignore bogus CNAME records that point right back at 404 // themselves. Without that check we can get into a case where we have two duplicate questions, 405 // A and B, and when we stop question A, UpdateQuestionDuplicates copies the value of CNAMEReferrals 406 // from A to B, and then A is re-appended to the end of the list as a duplicate of B (because 407 // the target name is still the same), and then when we stop question B, UpdateQuestionDuplicates 408 // copies the B's value of CNAMEReferrals back to A, and we end up not incrementing CNAMEReferrals 409 // for either of them. This is not a problem for CNAME loops of two or more records because in 410 // those cases the newly re-appended question A has a different target name and therefore cannot be 411 // a duplicate of any other question ('B') which was itself a duplicate of the previous question A. 412 413 // Right now we just stop and re-use the existing query. If we really wanted to be 100% perfect, 414 // and track CNAMEs coming and going, we should really create a subordinate query here, 415 // which we would subsequently cancel and retract if the CNAME referral record were removed. 416 // In reality this is such a corner case we'll ignore it until someone actually needs it. 417 418 LogInfo("AnswerQuestionByFollowingCNAME: %p %##s (%s) following CNAME referral %d for %s", 419 q, q->qname.c, DNSTypeName(q->qtype), q->CNAMEReferrals, RRDisplayString(m, rr)); 420 421 mDNS_StopQuery_internal(m, q); // Stop old query 422 AssignDomainName(&q->qname, &rr->rdata->u.name); // Update qname 423 q->qnamehash = DomainNameHashValue(&q->qname); // and namehash 424 // If a unicast query results in a CNAME that points to a .local, we need to re-try 425 // this as unicast. Setting the mDNSInterface_Unicast tells mDNS_StartQuery_internal 426 // to try this as unicast query even though it is a .local name 427 if (!mDNSOpaque16IsZero(q->TargetQID) && IsLocalDomain(&q->qname)) 428 { 429 LogInfo("AnswerQuestionByFollowingCNAME: Resolving a .local CNAME %p %##s (%s) Record %s", 430 q, q->qname.c, DNSTypeName(q->qtype), RRDisplayString(m, rr)); 431 q->InterfaceID = mDNSInterface_Unicast; 432 } 433 mDNS_StartQuery_internal(m, q); // start new query 434 // Record how many times we've done this. We need to do this *after* mDNS_StartQuery_internal, 435 // because mDNS_StartQuery_internal re-initializes CNAMEReferrals to zero 436 q->CNAMEReferrals = c; 437 } 438 } 439 440 // For a single given DNSQuestion pointed to by CurrentQuestion, deliver an add/remove result for the single given AuthRecord 441 // Note: All the callers should use the m->CurrentQuestion to see if the question is still valid or not 442 mDNSlocal void AnswerLocalQuestionWithLocalAuthRecord(mDNS *const m, AuthRecord *rr, QC_result AddRecord) 443 { 444 DNSQuestion *q = m->CurrentQuestion; 445 mDNSBool followcname; 446 447 if (!q) 448 { 449 LogMsg("AnswerLocalQuestionWithLocalAuthRecord: ERROR!! CurrentQuestion NULL while answering with %s", ARDisplayString(m, rr)); 450 return; 451 } 452 453 followcname = FollowCNAME(q, &rr->resrec, AddRecord); 454 455 // We should not be delivering results for record types Unregistered, Deregistering, and (unverified) Unique 456 if (!(rr->resrec.RecordType & kDNSRecordTypeActiveMask)) 457 { 458 LogMsg("AnswerLocalQuestionWithLocalAuthRecord: *NOT* delivering %s event for local record type %X %s", 459 AddRecord ? "Add" : "Rmv", rr->resrec.RecordType, ARDisplayString(m, rr)); 460 return; 461 } 462 463 // Indicate that we've given at least one positive answer for this record, so we should be prepared to send a goodbye for it 464 if (AddRecord) rr->AnsweredLocalQ = mDNStrue; 465 mDNS_DropLockBeforeCallback(); // Allow client to legally make mDNS API calls from the callback 466 if (q->QuestionCallback && !q->NoAnswer) 467 { 468 q->CurrentAnswers += AddRecord ? 1 : -1; 469 if (LORecordAnswersAddressType(rr)) 470 { 471 if (!followcname || q->ReturnIntermed) 472 { 473 // Don't send this packet on the wire as we answered from /etc/hosts 474 q->ThisQInterval = 0; 475 q->LOAddressAnswers += AddRecord ? 1 : -1; 476 q->QuestionCallback(m, q, &rr->resrec, AddRecord); 477 } 478 mDNS_ReclaimLockAfterCallback(); // Decrement mDNS_reentrancy to block mDNS API calls again 479 // The callback above could have caused the question to stop. Detect that 480 // using m->CurrentQuestion 481 if (followcname && m->CurrentQuestion == q) 482 AnswerQuestionByFollowingCNAME(m, q, &rr->resrec); 483 return; 484 } 485 else 486 q->QuestionCallback(m, q, &rr->resrec, AddRecord); 487 } 488 mDNS_ReclaimLockAfterCallback(); // Decrement mDNS_reentrancy to block mDNS API calls again 489 } 490 491 mDNSlocal void AnswerInterfaceAnyQuestionsWithLocalAuthRecord(mDNS *const m, AuthRecord *rr, QC_result AddRecord) 492 { 493 if (m->CurrentQuestion) 494 LogMsg("AnswerInterfaceAnyQuestionsWithLocalAuthRecord: ERROR m->CurrentQuestion already set: %##s (%s)", 495 m->CurrentQuestion->qname.c, DNSTypeName(m->CurrentQuestion->qtype)); 496 m->CurrentQuestion = m->Questions; 497 while (m->CurrentQuestion && m->CurrentQuestion != m->NewQuestions) 498 { 499 mDNSBool answered; 500 DNSQuestion *q = m->CurrentQuestion; 501 if (RRAny(rr)) 502 answered = ResourceRecordAnswersQuestion(&rr->resrec, q); 503 else 504 answered = LocalOnlyRecordAnswersQuestion(rr, q); 505 if (answered) 506 AnswerLocalQuestionWithLocalAuthRecord(m, rr, AddRecord); // MUST NOT dereference q again 507 if (m->CurrentQuestion == q) // If m->CurrentQuestion was not auto-advanced, do it ourselves now 508 m->CurrentQuestion = q->next; 509 } 510 m->CurrentQuestion = mDNSNULL; 511 } 512 513 // When a new local AuthRecord is created or deleted, AnswerAllLocalQuestionsWithLocalAuthRecord() 514 // delivers the appropriate add/remove events to listening questions: 515 // 1. It runs though all our LocalOnlyQuestions delivering answers as appropriate, 516 // stopping if it reaches a NewLocalOnlyQuestion -- brand-new questions are handled by AnswerNewLocalOnlyQuestion(). 517 // 2. If the AuthRecord is marked mDNSInterface_LocalOnly or mDNSInterface_P2P, then it also runs though 518 // our main question list, delivering answers to mDNSInterface_Any questions as appropriate, 519 // stopping if it reaches a NewQuestion -- brand-new questions are handled by AnswerNewQuestion(). 520 // 521 // AnswerAllLocalQuestionsWithLocalAuthRecord is used by the m->NewLocalRecords loop in mDNS_Execute(), 522 // and by mDNS_Deregister_internal() 523 524 mDNSlocal void AnswerAllLocalQuestionsWithLocalAuthRecord(mDNS *const m, AuthRecord *rr, QC_result AddRecord) 525 { 526 if (m->CurrentQuestion) 527 LogMsg("AnswerAllLocalQuestionsWithLocalAuthRecord ERROR m->CurrentQuestion already set: %##s (%s)", 528 m->CurrentQuestion->qname.c, DNSTypeName(m->CurrentQuestion->qtype)); 529 530 m->CurrentQuestion = m->LocalOnlyQuestions; 531 while (m->CurrentQuestion && m->CurrentQuestion != m->NewLocalOnlyQuestions) 532 { 533 mDNSBool answered; 534 DNSQuestion *q = m->CurrentQuestion; 535 // We are called with both LocalOnly/P2P record or a regular AuthRecord 536 if (RRAny(rr)) 537 answered = ResourceRecordAnswersQuestion(&rr->resrec, q); 538 else 539 answered = LocalOnlyRecordAnswersQuestion(rr, q); 540 if (answered) 541 AnswerLocalQuestionWithLocalAuthRecord(m, rr, AddRecord); // MUST NOT dereference q again 542 if (m->CurrentQuestion == q) // If m->CurrentQuestion was not auto-advanced, do it ourselves now 543 m->CurrentQuestion = q->next; 544 } 545 546 m->CurrentQuestion = mDNSNULL; 547 548 // If this AuthRecord is marked LocalOnly or P2P, then we want to deliver it to all local 'mDNSInterface_Any' questions 549 if (rr->ARType == AuthRecordLocalOnly || rr->ARType == AuthRecordP2P) 550 AnswerInterfaceAnyQuestionsWithLocalAuthRecord(m, rr, AddRecord); 551 552 } 553 554 // *************************************************************************** 555 #if COMPILER_LIKES_PRAGMA_MARK 556 #pragma mark - 557 #pragma mark - Resource Record Utility Functions 558 #endif 559 560 #define RRTypeIsAddressType(T) ((T) == kDNSType_A || (T) == kDNSType_AAAA) 561 562 #define ResourceRecordIsValidAnswer(RR) ( ((RR)-> resrec.RecordType & kDNSRecordTypeActiveMask) && \ 563 ((RR)->Additional1 == mDNSNULL || ((RR)->Additional1->resrec.RecordType & kDNSRecordTypeActiveMask)) && \ 564 ((RR)->Additional2 == mDNSNULL || ((RR)->Additional2->resrec.RecordType & kDNSRecordTypeActiveMask)) && \ 565 ((RR)->DependentOn == mDNSNULL || ((RR)->DependentOn->resrec.RecordType & kDNSRecordTypeActiveMask)) ) 566 567 #define ResourceRecordIsValidInterfaceAnswer(RR, INTID) \ 568 (ResourceRecordIsValidAnswer(RR) && \ 569 ((RR)->resrec.InterfaceID == mDNSInterface_Any || (RR)->resrec.InterfaceID == (INTID))) 570 571 #define DefaultProbeCountForTypeUnique ((mDNSu8)3) 572 #define DefaultProbeCountForRecordType(X) ((X) == kDNSRecordTypeUnique ? DefaultProbeCountForTypeUnique : (mDNSu8)0) 573 574 #define InitialAnnounceCount ((mDNSu8)8) 575 576 // For goodbye packets we set the count to 3, and for wakeups we set it to 18 577 // (which will be up to 15 wakeup attempts over the course of 30 seconds, 578 // and then if the machine fails to wake, 3 goodbye packets). 579 #define GoodbyeCount ((mDNSu8)3) 580 #define WakeupCount ((mDNSu8)18) 581 582 // Number of wakeups we send if WakeOnResolve is set in the question 583 #define InitialWakeOnResolveCount ((mDNSu8)3) 584 585 // Note that the announce intervals use exponential backoff, doubling each time. The probe intervals do not. 586 // This means that because the announce interval is doubled after sending the first packet, the first 587 // observed on-the-wire inter-packet interval between announcements is actually one second. 588 // The half-second value here may be thought of as a conceptual (non-existent) half-second delay *before* the first packet is sent. 589 #define DefaultProbeIntervalForTypeUnique (mDNSPlatformOneSecond/4) 590 #define DefaultAnnounceIntervalForTypeShared (mDNSPlatformOneSecond/2) 591 #define DefaultAnnounceIntervalForTypeUnique (mDNSPlatformOneSecond/2) 592 593 #define DefaultAPIntervalForRecordType(X) ((X) & kDNSRecordTypeActiveSharedMask ? DefaultAnnounceIntervalForTypeShared : \ 594 (X) & kDNSRecordTypeUnique ? DefaultProbeIntervalForTypeUnique : \ 595 (X) & kDNSRecordTypeActiveUniqueMask ? DefaultAnnounceIntervalForTypeUnique : 0) 596 597 #define TimeToAnnounceThisRecord(RR,time) ((RR)->AnnounceCount && (time) - ((RR)->LastAPTime + (RR)->ThisAPInterval) >= 0) 598 #define TimeToSendThisRecord(RR,time) ((TimeToAnnounceThisRecord(RR,time) || (RR)->ImmedAnswer) && ResourceRecordIsValidAnswer(RR)) 599 #define TicksTTL(RR) ((mDNSs32)(RR)->resrec.rroriginalttl * mDNSPlatformOneSecond) 600 #define RRExpireTime(RR) ((RR)->TimeRcvd + TicksTTL(RR)) 601 602 #define MaxUnansweredQueries 4 603 604 // SameResourceRecordSignature returns true if two resources records have the same name, type, and class, and may be sent 605 // (or were received) on the same interface (i.e. if *both* records specify an interface, then it has to match). 606 // TTL and rdata may differ. 607 // This is used for cache flush management: 608 // When sending a unique record, all other records matching "SameResourceRecordSignature" must also be sent 609 // When receiving a unique record, all old cache records matching "SameResourceRecordSignature" are flushed 610 611 // SameResourceRecordNameClassInterface is functionally the same as SameResourceRecordSignature, except rrtype does not have to match 612 613 #define SameResourceRecordSignature(A,B) (A)->resrec.rrtype == (B)->resrec.rrtype && SameResourceRecordNameClassInterface((A),(B)) 614 615 mDNSlocal mDNSBool SameResourceRecordNameClassInterface(const AuthRecord *const r1, const AuthRecord *const r2) 616 { 617 if (!r1) { LogMsg("SameResourceRecordSignature ERROR: r1 is NULL"); return(mDNSfalse); } 618 if (!r2) { LogMsg("SameResourceRecordSignature ERROR: r2 is NULL"); return(mDNSfalse); } 619 if (r1->resrec.InterfaceID && 620 r2->resrec.InterfaceID && 621 r1->resrec.InterfaceID != r2->resrec.InterfaceID) return(mDNSfalse); 622 return(mDNSBool)( 623 r1->resrec.rrclass == r2->resrec.rrclass && 624 r1->resrec.namehash == r2->resrec.namehash && 625 SameDomainName(r1->resrec.name, r2->resrec.name)); 626 } 627 628 // PacketRRMatchesSignature behaves as SameResourceRecordSignature, except that types may differ if our 629 // authoratative record is unique (as opposed to shared). For unique records, we are supposed to have 630 // complete ownership of *all* types for this name, so *any* record type with the same name is a conflict. 631 // In addition, when probing we send our questions with the wildcard type kDNSQType_ANY, 632 // so a response of any type should match, even if it is not actually the type the client plans to use. 633 634 // For now, to make it easier to avoid false conflicts, we treat SPS Proxy records like shared records, 635 // and require the rrtypes to match for the rdata to be considered potentially conflicting 636 mDNSlocal mDNSBool PacketRRMatchesSignature(const CacheRecord *const pktrr, const AuthRecord *const authrr) 637 { 638 if (!pktrr) { LogMsg("PacketRRMatchesSignature ERROR: pktrr is NULL"); return(mDNSfalse); } 639 if (!authrr) { LogMsg("PacketRRMatchesSignature ERROR: authrr is NULL"); return(mDNSfalse); } 640 if (pktrr->resrec.InterfaceID && 641 authrr->resrec.InterfaceID && 642 pktrr->resrec.InterfaceID != authrr->resrec.InterfaceID) return(mDNSfalse); 643 if (!(authrr->resrec.RecordType & kDNSRecordTypeUniqueMask) || authrr->WakeUp.HMAC.l[0]) 644 if (pktrr->resrec.rrtype != authrr->resrec.rrtype) return(mDNSfalse); 645 return(mDNSBool)( 646 pktrr->resrec.rrclass == authrr->resrec.rrclass && 647 pktrr->resrec.namehash == authrr->resrec.namehash && 648 SameDomainName(pktrr->resrec.name, authrr->resrec.name)); 649 } 650 651 // CacheRecord *ka is the CacheRecord from the known answer list in the query. 652 // This is the information that the requester believes to be correct. 653 // AuthRecord *rr is the answer we are proposing to give, if not suppressed. 654 // This is the information that we believe to be correct. 655 // We've already determined that we plan to give this answer on this interface 656 // (either the record is non-specific, or it is specific to this interface) 657 // so now we just need to check the name, type, class, rdata and TTL. 658 mDNSlocal mDNSBool ShouldSuppressKnownAnswer(const CacheRecord *const ka, const AuthRecord *const rr) 659 { 660 // If RR signature is different, or data is different, then don't suppress our answer 661 if (!IdenticalResourceRecord(&ka->resrec, &rr->resrec)) return(mDNSfalse); 662 663 // If the requester's indicated TTL is less than half the real TTL, 664 // we need to give our answer before the requester's copy expires. 665 // If the requester's indicated TTL is at least half the real TTL, 666 // then we can suppress our answer this time. 667 // If the requester's indicated TTL is greater than the TTL we believe, 668 // then that's okay, and we don't need to do anything about it. 669 // (If two responders on the network are offering the same information, 670 // that's okay, and if they are offering the information with different TTLs, 671 // the one offering the lower TTL should defer to the one offering the higher TTL.) 672 return(mDNSBool)(ka->resrec.rroriginalttl >= rr->resrec.rroriginalttl / 2); 673 } 674 675 mDNSlocal void SetNextAnnounceProbeTime(mDNS *const m, const AuthRecord *const rr) 676 { 677 if (rr->resrec.RecordType == kDNSRecordTypeUnique) 678 { 679 if ((rr->LastAPTime + rr->ThisAPInterval) - m->timenow > mDNSPlatformOneSecond * 10) 680 { 681 LogMsg("SetNextAnnounceProbeTime: ProbeCount %d Next in %d %s", rr->ProbeCount, (rr->LastAPTime + rr->ThisAPInterval) - m->timenow, ARDisplayString(m, rr)); 682 LogMsg("SetNextAnnounceProbeTime: m->SuppressProbes %d m->timenow %d diff %d", m->SuppressProbes, m->timenow, m->SuppressProbes - m->timenow); 683 } 684 if (m->NextScheduledProbe - (rr->LastAPTime + rr->ThisAPInterval) >= 0) 685 m->NextScheduledProbe = (rr->LastAPTime + rr->ThisAPInterval); 686 // Some defensive code: 687 // If (rr->LastAPTime + rr->ThisAPInterval) happens to be far in the past, we don't want to allow 688 // NextScheduledProbe to be set excessively in the past, because that can cause bad things to happen. 689 // See: <rdar://problem/7795434> mDNS: Sometimes advertising stops working and record interval is set to zero 690 if (m->NextScheduledProbe - m->timenow < 0) 691 m->NextScheduledProbe = m->timenow; 692 } 693 else if (rr->AnnounceCount && (ResourceRecordIsValidAnswer(rr) || rr->resrec.RecordType == kDNSRecordTypeDeregistering)) 694 { 695 if (m->NextScheduledResponse - (rr->LastAPTime + rr->ThisAPInterval) >= 0) 696 m->NextScheduledResponse = (rr->LastAPTime + rr->ThisAPInterval); 697 } 698 } 699 700 mDNSlocal void InitializeLastAPTime(mDNS *const m, AuthRecord *const rr) 701 { 702 // For reverse-mapping Sleep Proxy PTR records, probe interval is one second 703 rr->ThisAPInterval = rr->AddressProxy.type ? mDNSPlatformOneSecond : DefaultAPIntervalForRecordType(rr->resrec.RecordType); 704 705 // * If this is a record type that's going to probe, then we use the m->SuppressProbes time. 706 // * Otherwise, if it's not going to probe, but m->SuppressProbes is set because we have other 707 // records that are going to probe, then we delay its first announcement so that it will 708 // go out synchronized with the first announcement for the other records that *are* probing. 709 // This is a minor performance tweak that helps keep groups of related records synchronized together. 710 // The addition of "interval / 2" is to make sure that, in the event that any of the probes are 711 // delayed by a few milliseconds, this announcement does not inadvertently go out *before* the probing is complete. 712 // When the probing is complete and those records begin to announce, these records will also be picked up and accelerated, 713 // because they will meet the criterion of being at least half-way to their scheduled announcement time. 714 // * If it's not going to probe and m->SuppressProbes is not already set then we should announce immediately. 715 716 if (rr->ProbeCount) 717 { 718 // If we have no probe suppression time set, or it is in the past, set it now 719 if (m->SuppressProbes == 0 || m->SuppressProbes - m->timenow < 0) 720 { 721 // To allow us to aggregate probes when a group of services are registered together, 722 // the first probe is delayed 1/4 second. This means the common-case behaviour is: 723 // 1/4 second wait; probe 724 // 1/4 second wait; probe 725 // 1/4 second wait; probe 726 // 1/4 second wait; announce (i.e. service is normally announced exactly one second after being registered) 727 m->SuppressProbes = NonZeroTime(m->timenow + DefaultProbeIntervalForTypeUnique/2 + mDNSRandom(DefaultProbeIntervalForTypeUnique/2)); 728 729 // If we already have a *probe* scheduled to go out sooner, then use that time to get better aggregation 730 if (m->SuppressProbes - m->NextScheduledProbe >= 0) 731 m->SuppressProbes = NonZeroTime(m->NextScheduledProbe); 732 if (m->SuppressProbes - m->timenow < 0) // Make sure we don't set m->SuppressProbes excessively in the past 733 m->SuppressProbes = m->timenow; 734 735 // If we already have a *query* scheduled to go out sooner, then use that time to get better aggregation 736 if (m->SuppressProbes - m->NextScheduledQuery >= 0) 737 m->SuppressProbes = NonZeroTime(m->NextScheduledQuery); 738 if (m->SuppressProbes - m->timenow < 0) // Make sure we don't set m->SuppressProbes excessively in the past 739 m->SuppressProbes = m->timenow; 740 741 // except... don't expect to be able to send before the m->SuppressSending timer fires 742 if (m->SuppressSending && m->SuppressProbes - m->SuppressSending < 0) 743 m->SuppressProbes = NonZeroTime(m->SuppressSending); 744 745 if (m->SuppressProbes - m->timenow > mDNSPlatformOneSecond * 8) 746 { 747 LogMsg("InitializeLastAPTime ERROR m->SuppressProbes %d m->NextScheduledProbe %d m->NextScheduledQuery %d m->SuppressSending %d %d", 748 m->SuppressProbes - m->timenow, 749 m->NextScheduledProbe - m->timenow, 750 m->NextScheduledQuery - m->timenow, 751 m->SuppressSending, 752 m->SuppressSending - m->timenow); 753 m->SuppressProbes = NonZeroTime(m->timenow + DefaultProbeIntervalForTypeUnique/2 + mDNSRandom(DefaultProbeIntervalForTypeUnique/2)); 754 } 755 } 756 rr->LastAPTime = m->SuppressProbes - rr->ThisAPInterval; 757 } 758 else if (m->SuppressProbes && m->SuppressProbes - m->timenow >= 0) 759 rr->LastAPTime = m->SuppressProbes - rr->ThisAPInterval + DefaultProbeIntervalForTypeUnique * DefaultProbeCountForTypeUnique + rr->ThisAPInterval / 2; 760 else 761 rr->LastAPTime = m->timenow - rr->ThisAPInterval; 762 763 // For reverse-mapping Sleep Proxy PTR records we don't want to start probing instantly -- we 764 // wait one second to give the client a chance to go to sleep, and then start our ARP/NDP probing. 765 // After three probes one second apart with no answer, we conclude the client is now sleeping 766 // and we can begin broadcasting our announcements to take over ownership of that IP address. 767 // If we don't wait for the client to go to sleep, then when the client sees our ARP Announcements there's a risk 768 // (depending on the OS and networking stack it's using) that it might interpret it as a conflict and change its IP address. 769 if (rr->AddressProxy.type) rr->LastAPTime = m->timenow; 770 771 // Unsolicited Neighbor Advertisements (RFC 2461 Section 7.2.6) give us fast address cache updating, 772 // but some older IPv6 clients get confused by them, so for now we don't send them. Without Unsolicited 773 // Neighbor Advertisements we have to rely on Neighbor Unreachability Detection instead, which is slower. 774 // Given this, we'll do our best to wake for existing IPv6 connections, but we don't want to encourage 775 // new ones for sleeping clients, so we'll we send deletions for our SPS clients' AAAA records. 776 if (m->KnownBugs & mDNS_KnownBug_LimitedIPv6) 777 if (rr->WakeUp.HMAC.l[0] && rr->resrec.rrtype == kDNSType_AAAA) 778 rr->LastAPTime = m->timenow - rr->ThisAPInterval + mDNSPlatformOneSecond * 10; 779 780 // Set LastMCTime to now, to inhibit multicast responses 781 // (no need to send additional multicast responses when we're announcing anyway) 782 rr->LastMCTime = m->timenow; 783 rr->LastMCInterface = mDNSInterfaceMark; 784 785 SetNextAnnounceProbeTime(m, rr); 786 } 787 788 mDNSlocal const domainname *SetUnicastTargetToHostName(mDNS *const m, AuthRecord *rr) 789 { 790 const domainname *target; 791 if (rr->AutoTarget) 792 { 793 // For autotunnel services pointing at our IPv6 ULA we don't need or want a NAT mapping, but for all other 794 // advertised services referencing our uDNS hostname, we want NAT mappings automatically created as appropriate, 795 // with the port number in our advertised SRV record automatically tracking the external mapped port. 796 DomainAuthInfo *AuthInfo = GetAuthInfoForName_internal(m, rr->resrec.name); 797 if (!AuthInfo || !AuthInfo->AutoTunnel) rr->AutoTarget = Target_AutoHostAndNATMAP; 798 } 799 800 target = GetServiceTarget(m, rr); 801 if (!target || target->c[0] == 0) 802 { 803 // defer registration until we've got a target 804 LogInfo("SetUnicastTargetToHostName No target for %s", ARDisplayString(m, rr)); 805 rr->state = regState_NoTarget; 806 return mDNSNULL; 807 } 808 else 809 { 810 LogInfo("SetUnicastTargetToHostName target %##s for resource record %s", target->c, ARDisplayString(m,rr)); 811 return target; 812 } 813 } 814 815 // Right now this only applies to mDNS (.local) services where the target host is always m->MulticastHostname 816 // Eventually we should unify this with GetServiceTarget() in uDNS.c 817 mDNSlocal void SetTargetToHostName(mDNS *const m, AuthRecord *const rr) 818 { 819 domainname *const target = GetRRDomainNameTarget(&rr->resrec); 820 const domainname *newname = &m->MulticastHostname; 821 822 if (!target) LogInfo("SetTargetToHostName: Don't know how to set the target of rrtype %s", DNSTypeName(rr->resrec.rrtype)); 823 824 if (!(rr->ForceMCast || rr->ARType == AuthRecordLocalOnly || rr->ARType == AuthRecordP2P || IsLocalDomain(&rr->namestorage))) 825 { 826 const domainname *const n = SetUnicastTargetToHostName(m, rr); 827 if (n) newname = n; 828 else { target->c[0] = 0; SetNewRData(&rr->resrec, mDNSNULL, 0); return; } 829 } 830 831 if (target && SameDomainName(target, newname)) 832 debugf("SetTargetToHostName: Target of %##s is already %##s", rr->resrec.name->c, target->c); 833 834 if (target && !SameDomainName(target, newname)) 835 { 836 AssignDomainName(target, newname); 837 SetNewRData(&rr->resrec, mDNSNULL, 0); // Update rdlength, rdestimate, rdatahash 838 839 // If we're in the middle of probing this record, we need to start again, 840 // because changing its rdata may change the outcome of the tie-breaker. 841 // (If the record type is kDNSRecordTypeUnique (unconfirmed unique) then DefaultProbeCountForRecordType is non-zero.) 842 rr->ProbeCount = DefaultProbeCountForRecordType(rr->resrec.RecordType); 843 844 // If we've announced this record, we really should send a goodbye packet for the old rdata before 845 // changing to the new rdata. However, in practice, we only do SetTargetToHostName for unique records, 846 // so when we announce them we'll set the kDNSClass_UniqueRRSet and clear any stale data that way. 847 if (rr->RequireGoodbye && rr->resrec.RecordType == kDNSRecordTypeShared) 848 debugf("Have announced shared record %##s (%s) at least once: should have sent a goodbye packet before updating", 849 rr->resrec.name->c, DNSTypeName(rr->resrec.rrtype)); 850 851 rr->AnnounceCount = InitialAnnounceCount; 852 rr->RequireGoodbye = mDNSfalse; 853 InitializeLastAPTime(m, rr); 854 } 855 } 856 857 mDNSlocal void AcknowledgeRecord(mDNS *const m, AuthRecord *const rr) 858 { 859 if (rr->RecordCallback) 860 { 861 // CAUTION: MUST NOT do anything more with rr after calling rr->Callback(), because the client's callback function 862 // is allowed to do anything, including starting/stopping queries, registering/deregistering records, etc. 863 rr->Acknowledged = mDNStrue; 864 mDNS_DropLockBeforeCallback(); // Allow client to legally make mDNS API calls from the callback 865 rr->RecordCallback(m, rr, mStatus_NoError); 866 mDNS_ReclaimLockAfterCallback(); // Decrement mDNS_reentrancy to block mDNS API calls again 867 } 868 } 869 870 mDNSexport void ActivateUnicastRegistration(mDNS *const m, AuthRecord *const rr) 871 { 872 // Make sure that we don't activate the SRV record and associated service records, if it is in 873 // NoTarget state. First time when a service is being instantiated, SRV record may be in NoTarget state. 874 // We should not activate any of the other reords (PTR, TXT) that are part of the service. When 875 // the target becomes available, the records will be reregistered. 876 if (rr->resrec.rrtype != kDNSType_SRV) 877 { 878 AuthRecord *srvRR = mDNSNULL; 879 if (rr->resrec.rrtype == kDNSType_PTR) 880 srvRR = rr->Additional1; 881 else if (rr->resrec.rrtype == kDNSType_TXT) 882 srvRR = rr->DependentOn; 883 if (srvRR) 884 { 885 if (srvRR->resrec.rrtype != kDNSType_SRV) 886 { 887 LogMsg("ActivateUnicastRegistration: ERROR!! Resource record %s wrong, expecting SRV type", ARDisplayString(m, srvRR)); 888 } 889 else 890 { 891 LogInfo("ActivateUnicastRegistration: Found Service Record %s in state %d for %##s (%s)", 892 ARDisplayString(m, srvRR), srvRR->state, rr->resrec.name->c, DNSTypeName(rr->resrec.rrtype)); 893 rr->state = srvRR->state; 894 } 895 } 896 } 897 898 if (rr->state == regState_NoTarget) 899 { 900 LogInfo("ActivateUnicastRegistration record %s in regState_NoTarget, not activating", ARDisplayString(m, rr)); 901 return; 902 } 903 // When we wake up from sleep, we call ActivateUnicastRegistration. It is possible that just before we went to sleep, 904 // the service/record was being deregistered. In that case, we should not try to register again. For the cases where 905 // the records are deregistered due to e.g., no target for the SRV record, we would have returned from above if it 906 // was already in NoTarget state. If it was in the process of deregistration but did not complete fully before we went 907 // 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. 908 if (rr->resrec.RecordType == kDNSRecordTypeDeregistering) 909 { 910 LogInfo("ActivateUnicastRegistration: Resource record %s, current state %d, moving to DeregPending", ARDisplayString(m, rr), rr->state); 911 rr->state = regState_DeregPending; 912 } 913 else 914 { 915 LogInfo("ActivateUnicastRegistration: Resource record %s, current state %d, moving to Pending", ARDisplayString(m, rr), rr->state); 916 rr->state = regState_Pending; 917 } 918 rr->ProbeCount = 0; 919 rr->AnnounceCount = 0; 920 rr->ThisAPInterval = INIT_RECORD_REG_INTERVAL; 921 rr->LastAPTime = m->timenow - rr->ThisAPInterval; 922 rr->expire = 0; // Forget about all the leases, start fresh 923 rr->uselease = mDNStrue; 924 rr->updateid = zeroID; 925 rr->SRVChanged = mDNSfalse; 926 rr->updateError = mStatus_NoError; 927 // RestartRecordGetZoneData calls this function whenever a new interface gets registered with core. 928 // The records might already be registered with the server and hence could have NAT state. 929 if (rr->NATinfo.clientContext) 930 { 931 mDNS_StopNATOperation_internal(m, &rr->NATinfo); 932 rr->NATinfo.clientContext = mDNSNULL; 933 } 934 if (rr->nta) { CancelGetZoneData(m, rr->nta); rr->nta = mDNSNULL; } 935 if (rr->tcp) { DisposeTCPConn(rr->tcp); rr->tcp = mDNSNULL; } 936 if (m->NextuDNSEvent - (rr->LastAPTime + rr->ThisAPInterval) >= 0) 937 m->NextuDNSEvent = (rr->LastAPTime + rr->ThisAPInterval); 938 } 939 940 // Two records qualify to be local duplicates if: 941 // (a) the RecordTypes are the same, or 942 // (b) one is Unique and the other Verified 943 // (c) either is in the process of deregistering 944 #define RecordLDT(A,B) ((A)->resrec.RecordType == (B)->resrec.RecordType || \ 945 ((A)->resrec.RecordType | (B)->resrec.RecordType) == (kDNSRecordTypeUnique | kDNSRecordTypeVerified) || \ 946 ((A)->resrec.RecordType == kDNSRecordTypeDeregistering || (B)->resrec.RecordType == kDNSRecordTypeDeregistering)) 947 948 #define RecordIsLocalDuplicate(A,B) \ 949 ((A)->resrec.InterfaceID == (B)->resrec.InterfaceID && RecordLDT((A),(B)) && IdenticalResourceRecord(&(A)->resrec, &(B)->resrec)) 950 951 mDNSlocal AuthRecord *CheckAuthIdenticalRecord(AuthHash *r, AuthRecord *rr) 952 { 953 AuthGroup *a; 954 AuthGroup **ag = &a; 955 AuthRecord **rp; 956 const mDNSu32 slot = AuthHashSlot(rr->resrec.name); 957 958 a = AuthGroupForRecord(r, slot, &rr->resrec); 959 if (!a) return mDNSNULL; 960 rp = &(*ag)->members; 961 while (*rp) 962 { 963 if (!RecordIsLocalDuplicate(*rp, rr)) 964 rp=&(*rp)->next; 965 else 966 { 967 if ((*rp)->resrec.RecordType == kDNSRecordTypeDeregistering) 968 { 969 (*rp)->AnnounceCount = 0; 970 rp=&(*rp)->next; 971 } 972 else return *rp; 973 } 974 } 975 return (mDNSNULL); 976 } 977 978 mDNSlocal mDNSBool CheckAuthRecordConflict(AuthHash *r, AuthRecord *rr) 979 { 980 AuthGroup *a; 981 AuthGroup **ag = &a; 982 AuthRecord **rp; 983 const mDNSu32 slot = AuthHashSlot(rr->resrec.name); 984 985 a = AuthGroupForRecord(r, slot, &rr->resrec); 986 if (!a) return mDNSfalse; 987 rp = &(*ag)->members; 988 while (*rp) 989 { 990 const AuthRecord *s1 = rr->RRSet ? rr->RRSet : rr; 991 const AuthRecord *s2 = (*rp)->RRSet ? (*rp)->RRSet : *rp; 992 if (s1 != s2 && SameResourceRecordSignature((*rp), rr) && !IdenticalSameNameRecord(&(*rp)->resrec, &rr->resrec)) 993 return mDNStrue; 994 else 995 rp=&(*rp)->next; 996 } 997 return (mDNSfalse); 998 } 999 1000 // checks to see if "rr" is already present 1001 mDNSlocal AuthRecord *CheckAuthSameRecord(AuthHash *r, AuthRecord *rr) 1002 { 1003 AuthGroup *a; 1004 AuthGroup **ag = &a; 1005 AuthRecord **rp; 1006 const mDNSu32 slot = AuthHashSlot(rr->resrec.name); 1007 1008 a = AuthGroupForRecord(r, slot, &rr->resrec); 1009 if (!a) return mDNSNULL; 1010 rp = &(*ag)->members; 1011 while (*rp) 1012 { 1013 if (*rp != rr) 1014 rp=&(*rp)->next; 1015 else 1016 { 1017 return *rp; 1018 } 1019 } 1020 return (mDNSNULL); 1021 } 1022 1023 // Exported so uDNS.c can call this 1024 mDNSexport mStatus mDNS_Register_internal(mDNS *const m, AuthRecord *const rr) 1025 { 1026 domainname *target = GetRRDomainNameTarget(&rr->resrec); 1027 AuthRecord *r; 1028 AuthRecord **p = &m->ResourceRecords; 1029 AuthRecord **d = &m->DuplicateRecords; 1030 1031 if ((mDNSs32)rr->resrec.rroriginalttl <= 0) 1032 { LogMsg("mDNS_Register_internal: TTL %X should be 1 - 0x7FFFFFFF %s", rr->resrec.rroriginalttl, ARDisplayString(m, rr)); return(mStatus_BadParamErr); } 1033 1034 if (!rr->resrec.RecordType) 1035 { LogMsg("mDNS_Register_internal: RecordType must be non-zero %s", ARDisplayString(m, rr)); return(mStatus_BadParamErr); } 1036 1037 if (m->ShutdownTime) 1038 { LogMsg("mDNS_Register_internal: Shutting down, can't register %s", ARDisplayString(m, rr)); return(mStatus_ServiceNotRunning); } 1039 1040 if (m->DivertMulticastAdvertisements && !AuthRecord_uDNS(rr)) 1041 { 1042 mDNSInterfaceID previousID = rr->resrec.InterfaceID; 1043 if (rr->resrec.InterfaceID == mDNSInterface_Any || rr->resrec.InterfaceID == mDNSInterface_P2P) 1044 { 1045 rr->resrec.InterfaceID = mDNSInterface_LocalOnly; 1046 rr->ARType = AuthRecordLocalOnly; 1047 } 1048 if (rr->resrec.InterfaceID != mDNSInterface_LocalOnly) 1049 { 1050 NetworkInterfaceInfo *intf = FirstInterfaceForID(m, rr->resrec.InterfaceID); 1051 if (intf && !intf->Advertise){ rr->resrec.InterfaceID = mDNSInterface_LocalOnly; rr->ARType = AuthRecordLocalOnly; } 1052 } 1053 if (rr->resrec.InterfaceID != previousID) 1054 LogInfo("mDNS_Register_internal: Diverting record to local-only %s", ARDisplayString(m, rr)); 1055 } 1056 1057 if (RRLocalOnly(rr)) 1058 { 1059 if (CheckAuthSameRecord(&m->rrauth, rr)) 1060 { 1061 LogMsg("mDNS_Register_internal: ERROR!! Tried to register LocalOnly AuthRecord %p %##s (%s) that's already in the list", 1062 rr, rr->resrec.name->c, DNSTypeName(rr->resrec.rrtype)); 1063 return(mStatus_AlreadyRegistered); 1064 } 1065 } 1066 else 1067 { 1068 while (*p && *p != rr) p=&(*p)->next; 1069 if (*p) 1070 { 1071 LogMsg("mDNS_Register_internal: ERROR!! Tried to register AuthRecord %p %##s (%s) that's already in the list", 1072 rr, rr->resrec.name->c, DNSTypeName(rr->resrec.rrtype)); 1073 return(mStatus_AlreadyRegistered); 1074 } 1075 } 1076 1077 while (*d && *d != rr) d=&(*d)->next; 1078 if (*d) 1079 { 1080 LogMsg("mDNS_Register_internal: ERROR!! Tried to register AuthRecord %p %##s (%s) that's already in the Duplicate list", 1081 rr, rr->resrec.name->c, DNSTypeName(rr->resrec.rrtype)); 1082 return(mStatus_AlreadyRegistered); 1083 } 1084 1085 if (rr->DependentOn) 1086 { 1087 if (rr->resrec.RecordType == kDNSRecordTypeUnique) 1088 rr->resrec.RecordType = kDNSRecordTypeVerified; 1089 else 1090 { 1091 LogMsg("mDNS_Register_internal: ERROR! %##s (%s): rr->DependentOn && RecordType != kDNSRecordTypeUnique", 1092 rr->resrec.name->c, DNSTypeName(rr->resrec.rrtype)); 1093 return(mStatus_Invalid); 1094 } 1095 if (!(rr->DependentOn->resrec.RecordType & (kDNSRecordTypeUnique | kDNSRecordTypeVerified | kDNSRecordTypeKnownUnique))) 1096 { 1097 LogMsg("mDNS_Register_internal: ERROR! %##s (%s): rr->DependentOn->RecordType bad type %X", 1098 rr->resrec.name->c, DNSTypeName(rr->resrec.rrtype), rr->DependentOn->resrec.RecordType); 1099 return(mStatus_Invalid); 1100 } 1101 } 1102 1103 // If this resource record is referencing a specific interface, make sure it exists. 1104 // Skip checks for LocalOnly and P2P as they are not valid InterfaceIDs. Also, for scoped 1105 // entries in /etc/hosts skip that check as that interface may not be valid at this time. 1106 if (rr->resrec.InterfaceID && rr->ARType != AuthRecordLocalOnly && rr->ARType != AuthRecordP2P) 1107 { 1108 NetworkInterfaceInfo *intf = FirstInterfaceForID(m, rr->resrec.InterfaceID); 1109 if (!intf) 1110 { 1111 debugf("mDNS_Register_internal: Bogus InterfaceID %p in resource record", rr->resrec.InterfaceID); 1112 return(mStatus_BadReferenceErr); 1113 } 1114 } 1115 1116 rr->next = mDNSNULL; 1117 1118 // Field Group 1: The actual information pertaining to this resource record 1119 // Set up by client prior to call 1120 1121 // Field Group 2: Persistent metadata for Authoritative Records 1122 // rr->Additional1 = set to mDNSNULL in mDNS_SetupResourceRecord; may be overridden by client 1123 // rr->Additional2 = set to mDNSNULL in mDNS_SetupResourceRecord; may be overridden by client 1124 // rr->DependentOn = set to mDNSNULL in mDNS_SetupResourceRecord; may be overridden by client 1125 // rr->RRSet = set to mDNSNULL in mDNS_SetupResourceRecord; may be overridden by client 1126 // rr->Callback = already set in mDNS_SetupResourceRecord 1127 // rr->Context = already set in mDNS_SetupResourceRecord 1128 // rr->RecordType = already set in mDNS_SetupResourceRecord 1129 // rr->HostTarget = set to mDNSfalse in mDNS_SetupResourceRecord; may be overridden by client 1130 // rr->AllowRemoteQuery = set to mDNSfalse in mDNS_SetupResourceRecord; may be overridden by client 1131 // Make sure target is not uninitialized data, or we may crash writing debugging log messages 1132 if (rr->AutoTarget && target) target->c[0] = 0; 1133 1134 // Field Group 3: Transient state for Authoritative Records 1135 rr->Acknowledged = mDNSfalse; 1136 rr->ProbeCount = DefaultProbeCountForRecordType(rr->resrec.RecordType); 1137 rr->AnnounceCount = InitialAnnounceCount; 1138 rr->RequireGoodbye = mDNSfalse; 1139 rr->AnsweredLocalQ = mDNSfalse; 1140 rr->IncludeInProbe = mDNSfalse; 1141 rr->ImmedUnicast = mDNSfalse; 1142 rr->SendNSECNow = mDNSNULL; 1143 rr->ImmedAnswer = mDNSNULL; 1144 rr->ImmedAdditional = mDNSNULL; 1145 rr->SendRNow = mDNSNULL; 1146 rr->v4Requester = zerov4Addr; 1147 rr->v6Requester = zerov6Addr; 1148 rr->NextResponse = mDNSNULL; 1149 rr->NR_AnswerTo = mDNSNULL; 1150 rr->NR_AdditionalTo = mDNSNULL; 1151 if (!rr->AutoTarget) InitializeLastAPTime(m, rr); 1152 // rr->LastAPTime = Set for us in InitializeLastAPTime() 1153 // rr->LastMCTime = Set for us in InitializeLastAPTime() 1154 // rr->LastMCInterface = Set for us in InitializeLastAPTime() 1155 rr->NewRData = mDNSNULL; 1156 rr->newrdlength = 0; 1157 rr->UpdateCallback = mDNSNULL; 1158 rr->UpdateCredits = kMaxUpdateCredits; 1159 rr->NextUpdateCredit = 0; 1160 rr->UpdateBlocked = 0; 1161 1162 // For records we're holding as proxy (except reverse-mapping PTR records) two announcements is sufficient 1163 if (rr->WakeUp.HMAC.l[0] && !rr->AddressProxy.type) rr->AnnounceCount = 2; 1164 1165 // Field Group 4: Transient uDNS state for Authoritative Records 1166 rr->state = regState_Zero; 1167 rr->uselease = 0; 1168 rr->expire = 0; 1169 rr->Private = 0; 1170 rr->updateid = zeroID; 1171 rr->zone = rr->resrec.name; 1172 rr->nta = mDNSNULL; 1173 rr->tcp = mDNSNULL; 1174 rr->OrigRData = 0; 1175 rr->OrigRDLen = 0; 1176 rr->InFlightRData = 0; 1177 rr->InFlightRDLen = 0; 1178 rr->QueuedRData = 0; 1179 rr->QueuedRDLen = 0; 1180 //mDNSPlatformMemZero(&rr->NATinfo, sizeof(rr->NATinfo)); 1181 // We should be recording the actual internal port for this service record here. Once we initiate our NAT mapping 1182 // request we'll subsequently overwrite srv.port with the allocated external NAT port -- potentially multiple 1183 // times with different values if the external NAT port changes during the lifetime of the service registration. 1184 //if (rr->resrec.rrtype == kDNSType_SRV) rr->NATinfo.IntPort = rr->resrec.rdata->u.srv.port; 1185 1186 // rr->resrec.interface = already set in mDNS_SetupResourceRecord 1187 // rr->resrec.name->c = MUST be set by client 1188 // rr->resrec.rrtype = already set in mDNS_SetupResourceRecord 1189 // rr->resrec.rrclass = already set in mDNS_SetupResourceRecord 1190 // rr->resrec.rroriginalttl = already set in mDNS_SetupResourceRecord 1191 // rr->resrec.rdata = MUST be set by client, unless record type is CNAME or PTR and rr->HostTarget is set 1192 1193 // BIND named (name daemon) doesn't allow TXT records with zero-length rdata. This is strictly speaking correct, 1194 // since RFC 1035 specifies a TXT record as "One or more <character-string>s", not "Zero or more <character-string>s". 1195 // Since some legacy apps try to create zero-length TXT records, we'll silently correct it here. 1196 if (rr->resrec.rrtype == kDNSType_TXT && rr->resrec.rdlength == 0) { rr->resrec.rdlength = 1; rr->resrec.rdata->u.txt.c[0] = 0; } 1197 1198 if (rr->AutoTarget) 1199 { 1200 SetTargetToHostName(m, rr); // Also sets rdlength and rdestimate for us, and calls InitializeLastAPTime(); 1201 #ifndef UNICAST_DISABLED 1202 // If we have no target record yet, SetTargetToHostName will set rr->state == regState_NoTarget 1203 // 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. 1204 if (rr->state == regState_NoTarget) 1205 { 1206 // Initialize the target so that we don't crash while logging etc. 1207 domainname *tar = GetRRDomainNameTarget(&rr->resrec); 1208 if (tar) tar->c[0] = 0; 1209 LogInfo("mDNS_Register_internal: record %s in NoTarget state", ARDisplayString(m, rr)); 1210 } 1211 #endif 1212 } 1213 else 1214 { 1215 rr->resrec.rdlength = GetRDLength(&rr->resrec, mDNSfalse); 1216 rr->resrec.rdestimate = GetRDLength(&rr->resrec, mDNStrue); 1217 } 1218 1219 if (!ValidateDomainName(rr->resrec.name)) 1220 { LogMsg("Attempt to register record with invalid name: %s", ARDisplayString(m, rr)); return(mStatus_Invalid); } 1221 1222 // Don't do this until *after* we've set rr->resrec.rdlength 1223 if (!ValidateRData(rr->resrec.rrtype, rr->resrec.rdlength, rr->resrec.rdata)) 1224 { LogMsg("Attempt to register record with invalid rdata: %s", ARDisplayString(m, rr)); return(mStatus_Invalid); } 1225 1226 rr->resrec.namehash = DomainNameHashValue(rr->resrec.name); 1227 rr->resrec.rdatahash = target ? DomainNameHashValue(target) : RDataHashValue(&rr->resrec); 1228 1229 if (RRLocalOnly(rr)) 1230 { 1231 // If this is supposed to be unique, make sure we don't have any name conflicts. 1232 // If we found a conflict, we may still want to insert the record in the list but mark it appropriately 1233 // (kDNSRecordTypeDeregistering) so that we deliver RMV events to the application. But this causes more 1234 // complications and not clear whether there are any benefits. See rdar:9304275 for details. 1235 // Hence, just bail out. 1236 if (rr->resrec.RecordType & kDNSRecordTypeUniqueMask) 1237 { 1238 if (CheckAuthRecordConflict(&m->rrauth, rr)) 1239 { 1240 LogInfo("mDNS_Register_internal: Name conflict %s (%p), InterfaceID %p", ARDisplayString(m, rr), rr, rr->resrec.InterfaceID); 1241 return mStatus_NameConflict; 1242 } 1243 } 1244 } 1245 1246 // For uDNS records, we don't support duplicate checks at this time. 1247 #ifndef UNICAST_DISABLED 1248 if (AuthRecord_uDNS(rr)) 1249 { 1250 if (!m->NewLocalRecords) m->NewLocalRecords = rr; 1251 // When we called SetTargetToHostName, it may have caused mDNS_Register_internal to be re-entered, appending new 1252 // 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. 1253 // Note that for AutoTunnel this should never happen, but this check makes the code future-proof. 1254 while (*p) p=&(*p)->next; 1255 *p = rr; 1256 if (rr->resrec.RecordType == kDNSRecordTypeUnique) rr->resrec.RecordType = kDNSRecordTypeVerified; 1257 rr->ProbeCount = 0; 1258 rr->AnnounceCount = 0; 1259 if (rr->state != regState_NoTarget) ActivateUnicastRegistration(m, rr); 1260 return(mStatus_NoError); // <--- Note: For unicast records, code currently bails out at this point 1261 } 1262 #endif 1263 1264 // Now that we've finished building our new record, make sure it's not identical to one we already have 1265 if (RRLocalOnly(rr)) 1266 { 1267 rr->ProbeCount = 0; 1268 rr->AnnounceCount = 0; 1269 r = CheckAuthIdenticalRecord(&m->rrauth, rr); 1270 } 1271 else 1272 { 1273 for (r = m->ResourceRecords; r; r=r->next) 1274 if (RecordIsLocalDuplicate(r, rr)) 1275 { 1276 if (r->resrec.RecordType == kDNSRecordTypeDeregistering) r->AnnounceCount = 0; 1277 else break; 1278 } 1279 } 1280 1281 if (r) 1282 { 1283 debugf("mDNS_Register_internal:Adding to duplicate list %s", ARDisplayString(m,rr)); 1284 *d = rr; 1285 // If the previous copy of this record is already verified unique, 1286 // then indicate that we should move this record promptly to kDNSRecordTypeUnique state. 1287 // Setting ProbeCount to zero will cause SendQueries() to advance this record to 1288 // kDNSRecordTypeVerified state and call the client callback at the next appropriate time. 1289 if (rr->resrec.RecordType == kDNSRecordTypeUnique && r->resrec.RecordType == kDNSRecordTypeVerified) 1290 rr->ProbeCount = 0; 1291 } 1292 else 1293 { 1294 debugf("mDNS_Register_internal: Adding to active record list %s", ARDisplayString(m,rr)); 1295 if (RRLocalOnly(rr)) 1296 { 1297 AuthGroup *ag; 1298 ag = InsertAuthRecord(m, &m->rrauth, rr); 1299 if (ag && !ag->NewLocalOnlyRecords) { 1300 m->NewLocalOnlyRecords = mDNStrue; 1301 ag->NewLocalOnlyRecords = rr; 1302 } 1303 // No probing for LocalOnly records, Acknowledge them right away 1304 if (rr->resrec.RecordType == kDNSRecordTypeUnique) rr->resrec.RecordType = kDNSRecordTypeVerified; 1305 AcknowledgeRecord(m, rr); 1306 return(mStatus_NoError); 1307 } 1308 else 1309 { 1310 if (!m->NewLocalRecords) m->NewLocalRecords = rr; 1311 *p = rr; 1312 } 1313 } 1314 1315 if (!AuthRecord_uDNS(rr)) // This check is superfluous, given that for unicast records we (currently) bail out above 1316 { 1317 // For records that are not going to probe, acknowledge them right away 1318 if (rr->resrec.RecordType != kDNSRecordTypeUnique && rr->resrec.RecordType != kDNSRecordTypeDeregistering) 1319 AcknowledgeRecord(m, rr); 1320 1321 // Adding a record may affect whether or not we should sleep 1322 mDNS_UpdateAllowSleep(m); 1323 } 1324 1325 return(mStatus_NoError); 1326 } 1327 1328 mDNSlocal void RecordProbeFailure(mDNS *const m, const AuthRecord *const rr) 1329 { 1330 m->ProbeFailTime = m->timenow; 1331 m->NumFailedProbes++; 1332 // If we've had fifteen or more probe failures, rate-limit to one every five seconds. 1333 // If a bunch of hosts have all been configured with the same name, then they'll all 1334 // conflict and run through the same series of names: name-2, name-3, name-4, etc., 1335 // up to name-10. After that they'll start adding random increments in the range 1-100, 1336 // so they're more likely to branch out in the available namespace and settle on a set of 1337 // unique names quickly. If after five more tries the host is still conflicting, then we 1338 // may have a serious problem, so we start rate-limiting so we don't melt down the network. 1339 if (m->NumFailedProbes >= 15) 1340 { 1341 m->SuppressProbes = NonZeroTime(m->timenow + mDNSPlatformOneSecond * 5); 1342 LogMsg("Excessive name conflicts (%lu) for %##s (%s); rate limiting in effect", 1343 m->NumFailedProbes, rr->resrec.name->c, DNSTypeName(rr->resrec.rrtype)); 1344 } 1345 } 1346 1347 mDNSlocal void CompleteRDataUpdate(mDNS *const m, AuthRecord *const rr) 1348 { 1349 RData *OldRData = rr->resrec.rdata; 1350 mDNSu16 OldRDLen = rr->resrec.rdlength; 1351 SetNewRData(&rr->resrec, rr->NewRData, rr->newrdlength); // Update our rdata 1352 rr->NewRData = mDNSNULL; // Clear the NewRData pointer ... 1353 if (rr->UpdateCallback) 1354 rr->UpdateCallback(m, rr, OldRData, OldRDLen); // ... and let the client know 1355 } 1356 1357 // Note: mDNS_Deregister_internal can call a user callback, which may change the record list and/or question list. 1358 // Any code walking either list must use the CurrentQuestion and/or CurrentRecord mechanism to protect against this. 1359 // Exported so uDNS.c can call this 1360 mDNSexport mStatus mDNS_Deregister_internal(mDNS *const m, AuthRecord *const rr, mDNS_Dereg_type drt) 1361 { 1362 AuthRecord *r2; 1363 mDNSu8 RecordType = rr->resrec.RecordType; 1364 AuthRecord **p = &m->ResourceRecords; // Find this record in our list of active records 1365 mDNSBool dupList = mDNSfalse; 1366 1367 if (RRLocalOnly(rr)) 1368 { 1369 AuthGroup *a; 1370 AuthGroup **ag = &a; 1371 AuthRecord **rp; 1372 const mDNSu32 slot = AuthHashSlot(rr->resrec.name); 1373 1374 a = AuthGroupForRecord(&m->rrauth, slot, &rr->resrec); 1375 if (!a) return mDNSfalse; 1376 rp = &(*ag)->members; 1377 while (*rp && *rp != rr) rp=&(*rp)->next; 1378 p = rp; 1379 } 1380 else 1381 { 1382 while (*p && *p != rr) p=&(*p)->next; 1383 } 1384 1385 if (*p) 1386 { 1387 // We found our record on the main list. See if there are any duplicates that need special handling. 1388 if (drt == mDNS_Dereg_conflict) // If this was a conflict, see that all duplicates get the same treatment 1389 { 1390 // Scan for duplicates of rr, and mark them for deregistration at the end of this routine, after we've finished 1391 // deregistering rr. We need to do this scan *before* we give the client the chance to free and reuse the rr memory. 1392 for (r2 = m->DuplicateRecords; r2; r2=r2->next) if (RecordIsLocalDuplicate(r2, rr)) r2->ProbeCount = 0xFF; 1393 } 1394 else 1395 { 1396 // Before we delete the record (and potentially send a goodbye packet) 1397 // first see if we have a record on the duplicate list ready to take over from it. 1398 AuthRecord **d = &m->DuplicateRecords; 1399 while (*d && !RecordIsLocalDuplicate(*d, rr)) d=&(*d)->next; 1400 if (*d) 1401 { 1402 AuthRecord *dup = *d; 1403 debugf("mDNS_Register_internal: Duplicate record %p taking over from %p %##s (%s)", 1404 dup, rr, rr->resrec.name->c, DNSTypeName(rr->resrec.rrtype)); 1405 *d = dup->next; // Cut replacement record from DuplicateRecords list 1406 if (RRLocalOnly(rr)) 1407 { 1408 dup->next = mDNSNULL; 1409 if (!InsertAuthRecord(m, &m->rrauth, dup)) LogMsg("mDNS_Deregister_internal: ERROR!! cannot insert %s", ARDisplayString(m, dup)); 1410 } 1411 else 1412 { 1413 dup->next = rr->next; // And then... 1414 rr->next = dup; // ... splice it in right after the record we're about to delete 1415 } 1416 dup->resrec.RecordType = rr->resrec.RecordType; 1417 dup->ProbeCount = rr->ProbeCount; 1418 dup->AnnounceCount = rr->AnnounceCount; 1419 dup->RequireGoodbye = rr->RequireGoodbye; 1420 dup->AnsweredLocalQ = rr->AnsweredLocalQ; 1421 dup->ImmedAnswer = rr->ImmedAnswer; 1422 dup->ImmedUnicast = rr->ImmedUnicast; 1423 dup->ImmedAdditional = rr->ImmedAdditional; 1424 dup->v4Requester = rr->v4Requester; 1425 dup->v6Requester = rr->v6Requester; 1426 dup->ThisAPInterval = rr->ThisAPInterval; 1427 dup->LastAPTime = rr->LastAPTime; 1428 dup->LastMCTime = rr->LastMCTime; 1429 dup->LastMCInterface = rr->LastMCInterface; 1430 dup->Private = rr->Private; 1431 dup->state = rr->state; 1432 rr->RequireGoodbye = mDNSfalse; 1433 rr->AnsweredLocalQ = mDNSfalse; 1434 } 1435 } 1436 } 1437 else 1438 { 1439 // We didn't find our record on the main list; try the DuplicateRecords list instead. 1440 p = &m->DuplicateRecords; 1441 while (*p && *p != rr) p=&(*p)->next; 1442 // If we found our record on the duplicate list, then make sure we don't send a goodbye for it 1443 if (*p) { rr->RequireGoodbye = mDNSfalse; dupList = mDNStrue; } 1444 if (*p) debugf("mDNS_Deregister_internal: Deleting DuplicateRecord %p %##s (%s)", 1445 rr, rr->resrec.name->c, DNSTypeName(rr->resrec.rrtype)); 1446 } 1447 1448 if (!*p) 1449 { 1450 // No need to log an error message if we already know this is a potentially repeated deregistration 1451 if (drt != mDNS_Dereg_repeat) 1452 LogMsg("mDNS_Deregister_internal: Record %p not found in list %s", rr, ARDisplayString(m,rr)); 1453 return(mStatus_BadReferenceErr); 1454 } 1455 1456 // If this is a shared record and we've announced it at least once, 1457 // we need to retract that announcement before we delete the record 1458 1459 // If this is a record (including mDNSInterface_LocalOnly records) for which we've given local-only answers then 1460 // it's tempting to just do "AnswerAllLocalQuestionsWithLocalAuthRecord(m, rr, mDNSfalse)" here, but that would not not be safe. 1461 // The AnswerAllLocalQuestionsWithLocalAuthRecord routine walks the question list invoking client callbacks, using the "m->CurrentQuestion" 1462 // mechanism to cope with the client callback modifying the question list while that's happening. 1463 // However, mDNS_Deregister could have been called from a client callback (e.g. from the domain enumeration callback FoundDomain) 1464 // which means that the "m->CurrentQuestion" mechanism is already in use to protect that list, so we can't use it twice. 1465 // More generally, if we invoke callbacks from within a client callback, then those callbacks could deregister other 1466 // records, thereby invoking yet more callbacks, without limit. 1467 // The solution is to defer delivering the "Remove" events until mDNS_Execute time, just like we do for sending 1468 // actual goodbye packets. 1469 1470 #ifndef UNICAST_DISABLED 1471 if (AuthRecord_uDNS(rr)) 1472 { 1473 if (rr->RequireGoodbye) 1474 { 1475 if (rr->tcp) { DisposeTCPConn(rr->tcp); rr->tcp = mDNSNULL; } 1476 rr->resrec.RecordType = kDNSRecordTypeDeregistering; 1477 m->LocalRemoveEvents = mDNStrue; 1478 uDNS_DeregisterRecord(m, rr); 1479 // At this point unconditionally we bail out 1480 // Either uDNS_DeregisterRecord will have completed synchronously, and called CompleteDeregistration, 1481 // which calls us back here with RequireGoodbye set to false, or it will have initiated the deregistration 1482 // process and will complete asynchronously. Either way we don't need to do anything more here. 1483 return(mStatus_NoError); 1484 } 1485 // Sometimes the records don't complete proper deregistration i.e., don't wait for a response 1486 // from the server. In that case, if the records have been part of a group update, clear the 1487 // state here. Some recors e.g., AutoTunnel gets reused without ever being completely initialized 1488 rr->updateid = zeroID; 1489 1490 // We defer cleaning up NAT state only after sending goodbyes. This is important because 1491 // RecordRegistrationGotZoneData guards against creating NAT state if clientContext is non-NULL. 1492 // This happens today when we turn on/off interface where we get multiple network transitions 1493 // and RestartRecordGetZoneData triggers re-registration of the resource records even though 1494 // they may be in Registered state which causes NAT information to be setup multiple times. Defering 1495 // the cleanup here keeps clientContext non-NULL and hence prevents that. Note that cleaning up 1496 // NAT state here takes care of the case where we did not send goodbyes at all. 1497 if (rr->NATinfo.clientContext) 1498 { 1499 mDNS_StopNATOperation_internal(m, &rr->NATinfo); 1500 rr->NATinfo.clientContext = mDNSNULL; 1501 } 1502 if (rr->nta) { CancelGetZoneData(m, rr->nta); rr->nta = mDNSNULL; } 1503 if (rr->tcp) { DisposeTCPConn(rr->tcp); rr->tcp = mDNSNULL; } 1504 } 1505 #endif // UNICAST_DISABLED 1506 1507 if (RecordType == kDNSRecordTypeUnregistered) 1508 LogMsg("mDNS_Deregister_internal: %s already marked kDNSRecordTypeUnregistered", ARDisplayString(m, rr)); 1509 else if (RecordType == kDNSRecordTypeDeregistering) 1510 { 1511 LogMsg("mDNS_Deregister_internal: %s already marked kDNSRecordTypeDeregistering", ARDisplayString(m, rr)); 1512 return(mStatus_BadReferenceErr); 1513 } 1514 1515 // <rdar://problem/7457925> Local-only questions don't get remove events for unique records 1516 // We may want to consider changing this code so that we generate local-only question "rmv" 1517 // events (and maybe goodbye packets too) for unique records as well as for shared records 1518 // Note: If we change the logic for this "if" statement, need to ensure that the code in 1519 // CompleteDeregistration() sets the appropriate state variables to gaurantee that "else" 1520 // clause will execute here and the record will be cut from the list. 1521 if (rr->WakeUp.HMAC.l[0] || 1522 (RecordType == kDNSRecordTypeShared && (rr->RequireGoodbye || rr->AnsweredLocalQ))) 1523 { 1524 verbosedebugf("mDNS_Deregister_internal: Starting deregistration for %s", ARDisplayString(m, rr)); 1525 rr->resrec.RecordType = kDNSRecordTypeDeregistering; 1526 rr->resrec.rroriginalttl = 0; 1527 rr->AnnounceCount = rr->WakeUp.HMAC.l[0] ? WakeupCount : (drt == mDNS_Dereg_rapid) ? 1 : GoodbyeCount; 1528 rr->ThisAPInterval = mDNSPlatformOneSecond * 2; 1529 rr->LastAPTime = m->timenow - rr->ThisAPInterval; 1530 m->LocalRemoveEvents = mDNStrue; 1531 if (m->NextScheduledResponse - (m->timenow + mDNSPlatformOneSecond/10) >= 0) 1532 m->NextScheduledResponse = (m->timenow + mDNSPlatformOneSecond/10); 1533 } 1534 else 1535 { 1536 if (!dupList && RRLocalOnly(rr)) 1537 { 1538 AuthGroup *ag = RemoveAuthRecord(m, &m->rrauth, rr); 1539 if (ag->NewLocalOnlyRecords == rr) ag->NewLocalOnlyRecords = rr->next; 1540 } 1541 else 1542 { 1543 *p = rr->next; // Cut this record from the list 1544 if (m->NewLocalRecords == rr) m->NewLocalRecords = rr->next; 1545 } 1546 // If someone is about to look at this, bump the pointer forward 1547 if (m->CurrentRecord == rr) m->CurrentRecord = rr->next; 1548 rr->next = mDNSNULL; 1549 1550 // Should we generate local remove events here? 1551 // i.e. something like: 1552 // if (rr->AnsweredLocalQ) { AnswerAllLocalQuestionsWithLocalAuthRecord(m, rr, mDNSfalse); rr->AnsweredLocalQ = mDNSfalse; } 1553 1554 verbosedebugf("mDNS_Deregister_internal: Deleting record for %s", ARDisplayString(m, rr)); 1555 rr->resrec.RecordType = kDNSRecordTypeUnregistered; 1556 1557 if ((drt == mDNS_Dereg_conflict || drt == mDNS_Dereg_repeat) && RecordType == kDNSRecordTypeShared) 1558 debugf("mDNS_Deregister_internal: Cannot have a conflict on a shared record! %##s (%s)", 1559 rr->resrec.name->c, DNSTypeName(rr->resrec.rrtype)); 1560 1561 // If we have an update queued up which never executed, give the client a chance to free that memory 1562 if (rr->NewRData) CompleteRDataUpdate(m, rr); // Update our rdata, clear the NewRData pointer, and return memory to the client 1563 1564 1565 // CAUTION: MUST NOT do anything more with rr after calling rr->Callback(), because the client's callback function 1566 // is allowed to do anything, including starting/stopping queries, registering/deregistering records, etc. 1567 // In this case the likely client action to the mStatus_MemFree message is to free the memory, 1568 // so any attempt to touch rr after this is likely to lead to a crash. 1569 if (drt != mDNS_Dereg_conflict) 1570 { 1571 mDNS_DropLockBeforeCallback(); // Allow client to legally make mDNS API calls from the callback 1572 LogInfo("mDNS_Deregister_internal: mStatus_MemFree for %s", ARDisplayString(m, rr)); 1573 if (rr->RecordCallback) 1574 rr->RecordCallback(m, rr, mStatus_MemFree); // MUST NOT touch rr after this 1575 mDNS_ReclaimLockAfterCallback(); // Decrement mDNS_reentrancy to block mDNS API calls again 1576 } 1577 else 1578 { 1579 RecordProbeFailure(m, rr); 1580 mDNS_DropLockBeforeCallback(); // Allow client to legally make mDNS API calls from the callback 1581 if (rr->RecordCallback) 1582 rr->RecordCallback(m, rr, mStatus_NameConflict); // MUST NOT touch rr after this 1583 mDNS_ReclaimLockAfterCallback(); // Decrement mDNS_reentrancy to block mDNS API calls again 1584 // Now that we've finished deregistering rr, check our DuplicateRecords list for any that we marked previously. 1585 // Note that with all the client callbacks going on, by the time we get here all the 1586 // records we marked may have been explicitly deregistered by the client anyway. 1587 r2 = m->DuplicateRecords; 1588 while (r2) 1589 { 1590 if (r2->ProbeCount != 0xFF) r2 = r2->next; 1591 else { mDNS_Deregister_internal(m, r2, mDNS_Dereg_conflict); r2 = m->DuplicateRecords; } 1592 } 1593 } 1594 } 1595 mDNS_UpdateAllowSleep(m); 1596 return(mStatus_NoError); 1597 } 1598 1599 // *************************************************************************** 1600 #if COMPILER_LIKES_PRAGMA_MARK 1601 #pragma mark - 1602 #pragma mark - Packet Sending Functions 1603 #endif 1604 1605 mDNSlocal void AddRecordToResponseList(AuthRecord ***nrpp, AuthRecord *rr, AuthRecord *add) 1606 { 1607 if (rr->NextResponse == mDNSNULL && *nrpp != &rr->NextResponse) 1608 { 1609 **nrpp = rr; 1610 // NR_AdditionalTo must point to a record with NR_AnswerTo set (and not NR_AdditionalTo) 1611 // If 'add' does not meet this requirement, then follow its NR_AdditionalTo pointer to a record that does 1612 // The referenced record will definitely be acceptable (by recursive application of this rule) 1613 if (add && add->NR_AdditionalTo) add = add->NR_AdditionalTo; 1614 rr->NR_AdditionalTo = add; 1615 *nrpp = &rr->NextResponse; 1616 } 1617 debugf("AddRecordToResponseList: %##s (%s) already in list", rr->resrec.name->c, DNSTypeName(rr->resrec.rrtype)); 1618 } 1619 1620 mDNSlocal void AddAdditionalsToResponseList(mDNS *const m, AuthRecord *ResponseRecords, AuthRecord ***nrpp, const mDNSInterfaceID InterfaceID) 1621 { 1622 AuthRecord *rr, *rr2; 1623 for (rr=ResponseRecords; rr; rr=rr->NextResponse) // For each record we plan to put 1624 { 1625 // (Note: This is an "if", not a "while". If we add a record, we'll find it again 1626 // later in the "for" loop, and we will follow further "additional" links then.) 1627 if (rr->Additional1 && ResourceRecordIsValidInterfaceAnswer(rr->Additional1, InterfaceID)) 1628 AddRecordToResponseList(nrpp, rr->Additional1, rr); 1629 1630 if (rr->Additional2 && ResourceRecordIsValidInterfaceAnswer(rr->Additional2, InterfaceID)) 1631 AddRecordToResponseList(nrpp, rr->Additional2, rr); 1632 1633 // For SRV records, automatically add the Address record(s) for the target host 1634 if (rr->resrec.rrtype == kDNSType_SRV) 1635 { 1636 for (rr2=m->ResourceRecords; rr2; rr2=rr2->next) // Scan list of resource records 1637 if (RRTypeIsAddressType(rr2->resrec.rrtype) && // For all address records (A/AAAA) ... 1638 ResourceRecordIsValidInterfaceAnswer(rr2, InterfaceID) && // ... which are valid for answer ... 1639 rr->resrec.rdatahash == rr2->resrec.namehash && // ... whose name is the name of the SRV target 1640 SameDomainName(&rr->resrec.rdata->u.srv.target, rr2->resrec.name)) 1641 AddRecordToResponseList(nrpp, rr2, rr); 1642 } 1643 else if (RRTypeIsAddressType(rr->resrec.rrtype)) // For A or AAAA, put counterpart as additional 1644 { 1645 for (rr2=m->ResourceRecords; rr2; rr2=rr2->next) // Scan list of resource records 1646 if (RRTypeIsAddressType(rr2->resrec.rrtype) && // For all address records (A/AAAA) ... 1647 ResourceRecordIsValidInterfaceAnswer(rr2, InterfaceID) && // ... which are valid for answer ... 1648 rr->resrec.namehash == rr2->resrec.namehash && // ... and have the same name 1649 SameDomainName(rr->resrec.name, rr2->resrec.name)) 1650 AddRecordToResponseList(nrpp, rr2, rr); 1651 } 1652 else if (rr->resrec.rrtype == kDNSType_PTR) // For service PTR, see if we want to add DeviceInfo record 1653 { 1654 if (ResourceRecordIsValidInterfaceAnswer(&m->DeviceInfo, InterfaceID) && 1655 SameDomainLabel(rr->resrec.rdata->u.name.c, m->DeviceInfo.resrec.name->c)) 1656 AddRecordToResponseList(nrpp, &m->DeviceInfo, rr); 1657 } 1658 } 1659 } 1660 1661 mDNSlocal void SendDelayedUnicastResponse(mDNS *const m, const mDNSAddr *const dest, const mDNSInterfaceID InterfaceID) 1662 { 1663 AuthRecord *rr; 1664 AuthRecord *ResponseRecords = mDNSNULL; 1665 AuthRecord **nrp = &ResponseRecords; 1666 NetworkInterfaceInfo *intf = FirstInterfaceForID(m, InterfaceID); 1667 1668 // Make a list of all our records that need to be unicast to this destination 1669 for (rr = m->ResourceRecords; rr; rr=rr->next) 1670 { 1671 // If we find we can no longer unicast this answer, clear ImmedUnicast 1672 if (rr->ImmedAnswer == mDNSInterfaceMark || 1673 mDNSSameIPv4Address(rr->v4Requester, onesIPv4Addr) || 1674 mDNSSameIPv6Address(rr->v6Requester, onesIPv6Addr) ) 1675 rr->ImmedUnicast = mDNSfalse; 1676 1677 if (rr->ImmedUnicast && rr->ImmedAnswer == InterfaceID) 1678 { 1679 if ((dest->type == mDNSAddrType_IPv4 && mDNSSameIPv4Address(rr->v4Requester, dest->ip.v4)) || 1680 (dest->type == mDNSAddrType_IPv6 && mDNSSameIPv6Address(rr->v6Requester, dest->ip.v6))) 1681 { 1682 rr->ImmedAnswer = mDNSNULL; // Clear the state fields 1683 rr->ImmedUnicast = mDNSfalse; 1684 rr->v4Requester = zerov4Addr; 1685 rr->v6Requester = zerov6Addr; 1686 1687 // Only sent records registered for P2P over P2P interfaces 1688 if (intf && !mDNSPlatformValidRecordForInterface(rr, intf)) 1689 { 1690 LogInfo("SendDelayedUnicastResponse: Not sending %s, on %s", ARDisplayString(m, rr), InterfaceNameForID(m, InterfaceID)); 1691 continue; 1692 } 1693 1694 if (rr->NextResponse == mDNSNULL && nrp != &rr->NextResponse) // rr->NR_AnswerTo 1695 { rr->NR_AnswerTo = (mDNSu8*)~0; *nrp = rr; nrp = &rr->NextResponse; } 1696 } 1697 } 1698 } 1699 1700 AddAdditionalsToResponseList(m, ResponseRecords, &nrp, InterfaceID); 1701 1702 while (ResponseRecords) 1703 { 1704 mDNSu8 *responseptr = m->omsg.data; 1705 mDNSu8 *newptr; 1706 InitializeDNSMessage(&m->omsg.h, zeroID, ResponseFlags); 1707 1708 // Put answers in the packet 1709 while (ResponseRecords && ResponseRecords->NR_AnswerTo) 1710 { 1711 rr = ResponseRecords; 1712 if (rr->resrec.RecordType & kDNSRecordTypeUniqueMask) 1713 rr->resrec.rrclass |= kDNSClass_UniqueRRSet; // Temporarily set the cache flush bit so PutResourceRecord will set it 1714 newptr = PutResourceRecord(&m->omsg, responseptr, &m->omsg.h.numAnswers, &rr->resrec); 1715 rr->resrec.rrclass &= ~kDNSClass_UniqueRRSet; // Make sure to clear cache flush bit back to normal state 1716 if (!newptr && m->omsg.h.numAnswers) break; // If packet full, send it now 1717 if (newptr) responseptr = newptr; 1718 ResponseRecords = rr->NextResponse; 1719 rr->NextResponse = mDNSNULL; 1720 rr->NR_AnswerTo = mDNSNULL; 1721 rr->NR_AdditionalTo = mDNSNULL; 1722 rr->RequireGoodbye = mDNStrue; 1723 } 1724 1725 // Add additionals, if there's space 1726 while (ResponseRecords && !ResponseRecords->NR_AnswerTo) 1727 { 1728 rr = ResponseRecords; 1729 if (rr->resrec.RecordType & kDNSRecordTypeUniqueMask) 1730 rr->resrec.rrclass |= kDNSClass_UniqueRRSet; // Temporarily set the cache flush bit so PutResourceRecord will set it 1731 newptr = PutResourceRecord(&m->omsg, responseptr, &m->omsg.h.numAdditionals, &rr->resrec); 1732 rr->resrec.rrclass &= ~kDNSClass_UniqueRRSet; // Make sure to clear cache flush bit back to normal state 1733 1734 if (newptr) responseptr = newptr; 1735 if (newptr && m->omsg.h.numAnswers) rr->RequireGoodbye = mDNStrue; 1736 else if (rr->resrec.RecordType & kDNSRecordTypeUniqueMask) rr->ImmedAnswer = mDNSInterfaceMark; 1737 ResponseRecords = rr->NextResponse; 1738 rr->NextResponse = mDNSNULL; 1739 rr->NR_AnswerTo = mDNSNULL; 1740 rr->NR_AdditionalTo = mDNSNULL; 1741 } 1742 1743 if (m->omsg.h.numAnswers) 1744 mDNSSendDNSMessage(m, &m->omsg, responseptr, InterfaceID, mDNSNULL, dest, MulticastDNSPort, mDNSNULL, mDNSNULL); 1745 } 1746 } 1747 1748 // CompleteDeregistration guarantees that on exit the record will have been cut from the m->ResourceRecords list 1749 // and the client's mStatus_MemFree callback will have been invoked 1750 mDNSexport void CompleteDeregistration(mDNS *const m, AuthRecord *rr) 1751 { 1752 LogInfo("CompleteDeregistration: called for Resource record %s", ARDisplayString(m, rr)); 1753 // Clearing rr->RequireGoodbye signals mDNS_Deregister_internal() that 1754 // it should go ahead and immediately dispose of this registration 1755 rr->resrec.RecordType = kDNSRecordTypeShared; 1756 rr->RequireGoodbye = mDNSfalse; 1757 rr->WakeUp.HMAC = zeroEthAddr; 1758 if (rr->AnsweredLocalQ) { AnswerAllLocalQuestionsWithLocalAuthRecord(m, rr, mDNSfalse); rr->AnsweredLocalQ = mDNSfalse; } 1759 mDNS_Deregister_internal(m, rr, mDNS_Dereg_normal); // Don't touch rr after this 1760 } 1761 1762 // DiscardDeregistrations is used on shutdown and sleep to discard (forcibly and immediately) 1763 // any deregistering records that remain in the m->ResourceRecords list. 1764 // DiscardDeregistrations calls mDNS_Deregister_internal which can call a user callback, 1765 // which may change the record list and/or question list. 1766 // Any code walking either list must use the CurrentQuestion and/or CurrentRecord mechanism to protect against this. 1767 mDNSlocal void DiscardDeregistrations(mDNS *const m) 1768 { 1769 if (m->CurrentRecord) 1770 LogMsg("DiscardDeregistrations ERROR m->CurrentRecord already set %s", ARDisplayString(m, m->CurrentRecord)); 1771 m->CurrentRecord = m->ResourceRecords; 1772 1773 while (m->CurrentRecord) 1774 { 1775 AuthRecord *rr = m->CurrentRecord; 1776 if (!AuthRecord_uDNS(rr) && rr->resrec.RecordType == kDNSRecordTypeDeregistering) 1777 CompleteDeregistration(m, rr); // Don't touch rr after this 1778 else 1779 m->CurrentRecord = rr->next; 1780 } 1781 } 1782 1783 mDNSlocal mStatus GetLabelDecimalValue(const mDNSu8 *const src, mDNSu8 *dst) 1784 { 1785 int i, val = 0; 1786 if (src[0] < 1 || src[0] > 3) return(mStatus_Invalid); 1787 for (i=1; i<=src[0]; i++) 1788 { 1789 if (src[i] < '0' || src[i] > '9') return(mStatus_Invalid); 1790 val = val * 10 + src[i] - '0'; 1791 } 1792 if (val > 255) return(mStatus_Invalid); 1793 *dst = (mDNSu8)val; 1794 return(mStatus_NoError); 1795 } 1796 1797 mDNSlocal mStatus GetIPv4FromName(mDNSAddr *const a, const domainname *const name) 1798 { 1799 int skip = CountLabels(name) - 6; 1800 if (skip < 0) { LogMsg("GetIPFromName: Need six labels in IPv4 reverse mapping name %##s", name); return mStatus_Invalid; } 1801 if (GetLabelDecimalValue(SkipLeadingLabels(name, skip+3)->c, &a->ip.v4.b[0]) || 1802 GetLabelDecimalValue(SkipLeadingLabels(name, skip+2)->c, &a->ip.v4.b[1]) || 1803 GetLabelDecimalValue(SkipLeadingLabels(name, skip+1)->c, &a->ip.v4.b[2]) || 1804 GetLabelDecimalValue(SkipLeadingLabels(name, skip+0)->c, &a->ip.v4.b[3])) return mStatus_Invalid; 1805 a->type = mDNSAddrType_IPv4; 1806 return(mStatus_NoError); 1807 } 1808 1809 #define HexVal(X) ( ((X) >= '0' && (X) <= '9') ? ((X) - '0' ) : \ 1810 ((X) >= 'A' && (X) <= 'F') ? ((X) - 'A' + 10) : \ 1811 ((X) >= 'a' && (X) <= 'f') ? ((X) - 'a' + 10) : -1) 1812 1813 mDNSlocal mStatus GetIPv6FromName(mDNSAddr *const a, const domainname *const name) 1814 { 1815 int i, h, l; 1816 const domainname *n; 1817 1818 int skip = CountLabels(name) - 34; 1819 if (skip < 0) { LogMsg("GetIPFromName: Need 34 labels in IPv6 reverse mapping name %##s", name); return mStatus_Invalid; } 1820 1821 n = SkipLeadingLabels(name, skip); 1822 for (i=0; i<16; i++) 1823 { 1824 if (n->c[0] != 1) return mStatus_Invalid; 1825 l = HexVal(n->c[1]); 1826 n = (const domainname *)(n->c + 2); 1827 1828 if (n->c[0] != 1) return mStatus_Invalid; 1829 h = HexVal(n->c[1]); 1830 n = (const domainname *)(n->c + 2); 1831 1832 if (l<0 || h<0) return mStatus_Invalid; 1833 a->ip.v6.b[15-i] = (mDNSu8)((h << 4) | l); 1834 } 1835 1836 a->type = mDNSAddrType_IPv6; 1837 return(mStatus_NoError); 1838 } 1839 1840 mDNSlocal mDNSs32 ReverseMapDomainType(const domainname *const name) 1841 { 1842 int skip = CountLabels(name) - 2; 1843 if (skip >= 0) 1844 { 1845 const domainname *suffix = SkipLeadingLabels(name, skip); 1846 if (SameDomainName(suffix, (const domainname*)"\x7" "in-addr" "\x4" "arpa")) return mDNSAddrType_IPv4; 1847 if (SameDomainName(suffix, (const domainname*)"\x3" "ip6" "\x4" "arpa")) return mDNSAddrType_IPv6; 1848 } 1849 return(mDNSAddrType_None); 1850 } 1851 1852 mDNSlocal void SendARP(mDNS *const m, const mDNSu8 op, const AuthRecord *const rr, 1853 const mDNSv4Addr *const spa, const mDNSEthAddr *const tha, const mDNSv4Addr *const tpa, const mDNSEthAddr *const dst) 1854 { 1855 int i; 1856 mDNSu8 *ptr = m->omsg.data; 1857 NetworkInterfaceInfo *intf = FirstInterfaceForID(m, rr->resrec.InterfaceID); 1858 if (!intf) { LogMsg("SendARP: No interface with InterfaceID %p found %s", rr->resrec.InterfaceID, ARDisplayString(m,rr)); return; } 1859 1860 // 0x00 Destination address 1861 for (i=0; i<6; i++) *ptr++ = dst->b[i]; 1862 1863 // 0x06 Source address (Note: Since we don't currently set the BIOCSHDRCMPLT option, BPF will fill in the real interface address for us) 1864 for (i=0; i<6; i++) *ptr++ = intf->MAC.b[0]; 1865 1866 // 0x0C ARP Ethertype (0x0806) 1867 *ptr++ = 0x08; *ptr++ = 0x06; 1868 1869 // 0x0E ARP header 1870 *ptr++ = 0x00; *ptr++ = 0x01; // Hardware address space; Ethernet = 1 1871 *ptr++ = 0x08; *ptr++ = 0x00; // Protocol address space; IP = 0x0800 1872 *ptr++ = 6; // Hardware address length 1873 *ptr++ = 4; // Protocol address length 1874 *ptr++ = 0x00; *ptr++ = op; // opcode; Request = 1, Response = 2 1875 1876 // 0x16 Sender hardware address (our MAC address) 1877 for (i=0; i<6; i++) *ptr++ = intf->MAC.b[i]; 1878 1879 // 0x1C Sender protocol address 1880 for (i=0; i<4; i++) *ptr++ = spa->b[i]; 1881 1882 // 0x20 Target hardware address 1883 for (i=0; i<6; i++) *ptr++ = tha->b[i]; 1884 1885 // 0x26 Target protocol address 1886 for (i=0; i<4; i++) *ptr++ = tpa->b[i]; 1887 1888 // 0x2A Total ARP Packet length 42 bytes 1889 mDNSPlatformSendRawPacket(m->omsg.data, ptr, rr->resrec.InterfaceID); 1890 } 1891 1892 mDNSlocal mDNSu16 CheckSum(const void *const data, mDNSs32 length, mDNSu32 sum) 1893 { 1894 const mDNSu16 *ptr = data; 1895 while (length > 0) { length -= 2; sum += *ptr++; } 1896 sum = (sum & 0xFFFF) + (sum >> 16); 1897 sum = (sum & 0xFFFF) + (sum >> 16); 1898 return(sum != 0xFFFF ? sum : 0); 1899 } 1900 1901 mDNSlocal mDNSu16 IPv6CheckSum(const mDNSv6Addr *const src, const mDNSv6Addr *const dst, const mDNSu8 protocol, const void *const data, const mDNSu32 length) 1902 { 1903 IPv6PseudoHeader ph; 1904 ph.src = *src; 1905 ph.dst = *dst; 1906 ph.len.b[0] = length >> 24; 1907 ph.len.b[1] = length >> 16; 1908 ph.len.b[2] = length >> 8; 1909 ph.len.b[3] = length; 1910 ph.pro.b[0] = 0; 1911 ph.pro.b[1] = 0; 1912 ph.pro.b[2] = 0; 1913 ph.pro.b[3] = protocol; 1914 return CheckSum(&ph, sizeof(ph), CheckSum(data, length, 0)); 1915 } 1916 1917 mDNSlocal void SendNDP(mDNS *const m, const mDNSu8 op, const mDNSu8 flags, const AuthRecord *const rr, 1918 const mDNSv6Addr *const spa, const mDNSEthAddr *const tha, const mDNSv6Addr *const tpa, const mDNSEthAddr *const dst) 1919 { 1920 int i; 1921 mDNSOpaque16 checksum; 1922 mDNSu8 *ptr = m->omsg.data; 1923 // Some recipient hosts seem to ignore Neighbor Solicitations if the IPv6-layer destination address is not the 1924 // appropriate IPv6 solicited node multicast address, so we use that IPv6-layer destination address, even though 1925 // at the Ethernet-layer we unicast the packet to the intended target, to avoid wasting network bandwidth. 1926 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] } }; 1927 const mDNSv6Addr *const v6dst = (op == NDP_Sol) ? &mc : tpa; 1928 NetworkInterfaceInfo *intf = FirstInterfaceForID(m, rr->resrec.InterfaceID); 1929 if (!intf) { LogMsg("SendNDP: No interface with InterfaceID %p found %s", rr->resrec.InterfaceID, ARDisplayString(m,rr)); return; } 1930 1931 // 0x00 Destination address 1932 for (i=0; i<6; i++) *ptr++ = dst->b[i]; 1933 // Right now we only send Neighbor Solicitations to verify whether the host we're proxying for has gone to sleep yet. 1934 // Since we know who we're looking for, we send it via Ethernet-layer unicast, rather than bothering every host on the 1935 // link with a pointless link-layer multicast. 1936 // Should we want to send traditional Neighbor Solicitations in the future, where we really don't know in advance what 1937 // Ethernet-layer address we're looking for, we'll need to send to the appropriate Ethernet-layer multicast address: 1938 // *ptr++ = 0x33; 1939 // *ptr++ = 0x33; 1940 // *ptr++ = 0xFF; 1941 // *ptr++ = tpa->b[0xD]; 1942 // *ptr++ = tpa->b[0xE]; 1943 // *ptr++ = tpa->b[0xF]; 1944 1945 // 0x06 Source address (Note: Since we don't currently set the BIOCSHDRCMPLT option, BPF will fill in the real interface address for us) 1946 for (i=0; i<6; i++) *ptr++ = (tha ? *tha : intf->MAC).b[i]; 1947 1948 // 0x0C IPv6 Ethertype (0x86DD) 1949 *ptr++ = 0x86; *ptr++ = 0xDD; 1950 1951 // 0x0E IPv6 header 1952 *ptr++ = 0x60; *ptr++ = 0x00; *ptr++ = 0x00; *ptr++ = 0x00; // Version, Traffic Class, Flow Label 1953 *ptr++ = 0x00; *ptr++ = 0x20; // Length 1954 *ptr++ = 0x3A; // Protocol == ICMPv6 1955 *ptr++ = 0xFF; // Hop Limit 1956 1957 // 0x16 Sender IPv6 address 1958 for (i=0; i<16; i++) *ptr++ = spa->b[i]; 1959 1960 // 0x26 Destination IPv6 address 1961 for (i=0; i<16; i++) *ptr++ = v6dst->b[i]; 1962 1963 // 0x36 NDP header 1964 *ptr++ = op; // 0x87 == Neighbor Solicitation, 0x88 == Neighbor Advertisement 1965 *ptr++ = 0x00; // Code 1966 *ptr++ = 0x00; *ptr++ = 0x00; // Checksum placeholder (0x38, 0x39) 1967 *ptr++ = flags; 1968 *ptr++ = 0x00; *ptr++ = 0x00; *ptr++ = 0x00; 1969 1970 if (op == NDP_Sol) // Neighbor Solicitation. The NDP "target" is the address we seek. 1971 { 1972 // 0x3E NDP target. 1973 for (i=0; i<16; i++) *ptr++ = tpa->b[i]; 1974 // 0x4E Source Link-layer Address 1975 // <http://www.ietf.org/rfc/rfc2461.txt> 1976 // MUST NOT be included when the source IP address is the unspecified address. 1977 // Otherwise, on link layers that have addresses this option MUST be included 1978 // in multicast solicitations and SHOULD be included in unicast solicitations. 1979 if (!mDNSIPv6AddressIsZero(*spa)) 1980 { 1981 *ptr++ = NDP_SrcLL; // Option Type 1 == Source Link-layer Address 1982 *ptr++ = 0x01; // Option length 1 (in units of 8 octets) 1983 for (i=0; i<6; i++) *ptr++ = (tha ? *tha : intf->MAC).b[i]; 1984 } 1985 } 1986 else // Neighbor Advertisement. The NDP "target" is the address we're giving information about. 1987 { 1988 // 0x3E NDP target. 1989 for (i=0; i<16; i++) *ptr++ = spa->b[i]; 1990 // 0x4E Target Link-layer Address 1991 *ptr++ = NDP_TgtLL; // Option Type 2 == Target Link-layer Address 1992 *ptr++ = 0x01; // Option length 1 (in units of 8 octets) 1993 for (i=0; i<6; i++) *ptr++ = (tha ? *tha : intf->MAC).b[i]; 1994 } 1995 1996 // 0x4E or 0x56 Total NDP Packet length 78 or 86 bytes 1997 m->omsg.data[0x13] = ptr - &m->omsg.data[0x36]; // Compute actual length 1998 checksum.NotAnInteger = ~IPv6CheckSum(spa, v6dst, 0x3A, &m->omsg.data[0x36], m->omsg.data[0x13]); 1999 m->omsg.data[0x38] = checksum.b[0]; 2000 m->omsg.data[0x39] = checksum.b[1]; 2001 2002 mDNSPlatformSendRawPacket(m->omsg.data, ptr, rr->resrec.InterfaceID); 2003 } 2004 2005 mDNSlocal void SetupOwnerOpt(const mDNS *const m, const NetworkInterfaceInfo *const intf, rdataOPT *const owner) 2006 { 2007 owner->u.owner.vers = 0; 2008 owner->u.owner.seq = m->SleepSeqNum; 2009 owner->u.owner.HMAC = m->PrimaryMAC; 2010 owner->u.owner.IMAC = intf->MAC; 2011 owner->u.owner.password = zeroEthAddr; 2012 2013 // Don't try to compute the optlen until *after* we've set up the data fields 2014 // 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 2015 owner->opt = kDNSOpt_Owner; 2016 owner->optlen = DNSOpt_Owner_Space(&m->PrimaryMAC, &intf->MAC) - 4; 2017 } 2018 2019 mDNSlocal void GrantUpdateCredit(AuthRecord *rr) 2020 { 2021 if (++rr->UpdateCredits >= kMaxUpdateCredits) rr->NextUpdateCredit = 0; 2022 else rr->NextUpdateCredit = NonZeroTime(rr->NextUpdateCredit + kUpdateCreditRefreshInterval); 2023 } 2024 2025 // Note about acceleration of announcements to facilitate automatic coalescing of 2026 // multiple independent threads of announcements into a single synchronized thread: 2027 // The announcements in the packet may be at different stages of maturity; 2028 // One-second interval, two-second interval, four-second interval, and so on. 2029 // After we've put in all the announcements that are due, we then consider 2030 // whether there are other nearly-due announcements that are worth accelerating. 2031 // To be eligible for acceleration, a record MUST NOT be older (further along 2032 // its timeline) than the most mature record we've already put in the packet. 2033 // In other words, younger records can have their timelines accelerated to catch up 2034 // with their elder bretheren; this narrows the age gap and helps them eventually get in sync. 2035 // Older records cannot have their timelines accelerated; this would just widen 2036 // the gap between them and their younger bretheren and get them even more out of sync. 2037 2038 // Note: SendResponses calls mDNS_Deregister_internal which can call a user callback, which may change 2039 // the record list and/or question list. 2040 // Any code walking either list must use the CurrentQuestion and/or CurrentRecord mechanism to protect against this. 2041 mDNSlocal void SendResponses(mDNS *const m) 2042 { 2043 int pktcount = 0; 2044 AuthRecord *rr, *r2; 2045 mDNSs32 maxExistingAnnounceInterval = 0; 2046 const NetworkInterfaceInfo *intf = GetFirstActiveInterface(m->HostInterfaces); 2047 2048 m->NextScheduledResponse = m->timenow + 0x78000000; 2049 2050 if (m->SleepState == SleepState_Transferring) RetrySPSRegistrations(m); 2051 2052 for (rr = m->ResourceRecords; rr; rr=rr->next) 2053 if (rr->ImmedUnicast) 2054 { 2055 mDNSAddr v4 = { mDNSAddrType_IPv4, {{{0}}} }; 2056 mDNSAddr v6 = { mDNSAddrType_IPv6, {{{0}}} }; 2057 v4.ip.v4 = rr->v4Requester; 2058 v6.ip.v6 = rr->v6Requester; 2059 if (!mDNSIPv4AddressIsZero(rr->v4Requester)) SendDelayedUnicastResponse(m, &v4, rr->ImmedAnswer); 2060 if (!mDNSIPv6AddressIsZero(rr->v6Requester)) SendDelayedUnicastResponse(m, &v6, rr->ImmedAnswer); 2061 if (rr->ImmedUnicast) 2062 { 2063 LogMsg("SendResponses: ERROR: rr->ImmedUnicast still set: %s", ARDisplayString(m, rr)); 2064 rr->ImmedUnicast = mDNSfalse; 2065 } 2066 } 2067 2068 // *** 2069 // *** 1. Setup: Set the SendRNow and ImmedAnswer fields to indicate which interface(s) the records need to be sent on 2070 // *** 2071 2072 // Run through our list of records, and decide which ones we're going to announce on all interfaces 2073 for (rr = m->ResourceRecords; rr; rr=rr->next) 2074 { 2075 while (rr->NextUpdateCredit && m->timenow - rr->NextUpdateCredit >= 0) GrantUpdateCredit(rr); 2076 if (TimeToAnnounceThisRecord(rr, m->timenow)) 2077 { 2078 if (rr->resrec.RecordType == kDNSRecordTypeDeregistering) 2079 { 2080 if (!rr->WakeUp.HMAC.l[0]) 2081 { 2082 if (rr->AnnounceCount) rr->ImmedAnswer = mDNSInterfaceMark; // Send goodbye packet on all interfaces 2083 } 2084 else 2085 { 2086 LogSPS("SendResponses: Sending wakeup %2d for %.6a %s", rr->AnnounceCount-3, &rr->WakeUp.IMAC, ARDisplayString(m, rr)); 2087 SendWakeup(m, rr->resrec.InterfaceID, &rr->WakeUp.IMAC, &rr->WakeUp.password); 2088 for (r2 = rr; r2; r2=r2->next) 2089 if (r2->AnnounceCount && r2->resrec.InterfaceID == rr->resrec.InterfaceID && mDNSSameEthAddress(&r2->WakeUp.IMAC, &rr->WakeUp.IMAC)) 2090 { 2091 // For now we only want to send a single Unsolicited Neighbor Advertisement restoring the address to the original 2092 // owner, because these packets can cause some IPv6 stacks to falsely conclude that there's an address conflict. 2093 if (r2->AddressProxy.type == mDNSAddrType_IPv6 && r2->AnnounceCount == WakeupCount) 2094 { 2095 LogSPS("NDP Announcement %2d Releasing traffic for H-MAC %.6a I-MAC %.6a %s", 2096 r2->AnnounceCount-3, &r2->WakeUp.HMAC, &r2->WakeUp.IMAC, ARDisplayString(m,r2)); 2097 SendNDP(m, NDP_Adv, NDP_Override, r2, &r2->AddressProxy.ip.v6, &r2->WakeUp.IMAC, &AllHosts_v6, &AllHosts_v6_Eth); 2098 } 2099 r2->LastAPTime = m->timenow; 2100 // After 15 wakeups without success (maybe host has left the network) send three goodbyes instead 2101 if (--r2->AnnounceCount <= GoodbyeCount) r2->WakeUp.HMAC = zeroEthAddr; 2102 } 2103 } 2104 } 2105 else if (ResourceRecordIsValidAnswer(rr)) 2106 { 2107 if (rr->AddressProxy.type) 2108 { 2109 rr->AnnounceCount--; 2110 rr->ThisAPInterval *= 2; 2111 rr->LastAPTime = m->timenow; 2112 if (rr->AddressProxy.type == mDNSAddrType_IPv4) 2113 { 2114 LogSPS("ARP Announcement %2d Capturing traffic for H-MAC %.6a I-MAC %.6a %s", 2115 rr->AnnounceCount, &rr->WakeUp.HMAC, &rr->WakeUp.IMAC, ARDisplayString(m,rr)); 2116 SendARP(m, 1, rr, &rr->AddressProxy.ip.v4, &zeroEthAddr, &rr->AddressProxy.ip.v4, &onesEthAddr); 2117 } 2118 else if (rr->AddressProxy.type == mDNSAddrType_IPv6) 2119 { 2120 LogSPS("NDP Announcement %2d Capturing traffic for H-MAC %.6a I-MAC %.6a %s", 2121 rr->AnnounceCount, &rr->WakeUp.HMAC, &rr->WakeUp.IMAC, ARDisplayString(m,rr)); 2122 SendNDP(m, NDP_Adv, NDP_Override, rr, &rr->AddressProxy.ip.v6, mDNSNULL, &AllHosts_v6, &AllHosts_v6_Eth); 2123 } 2124 } 2125 else 2126 { 2127 rr->ImmedAnswer = mDNSInterfaceMark; // Send on all interfaces 2128 if (maxExistingAnnounceInterval < rr->ThisAPInterval) 2129 maxExistingAnnounceInterval = rr->ThisAPInterval; 2130 if (rr->UpdateBlocked) rr->UpdateBlocked = 0; 2131 } 2132 } 2133 } 2134 } 2135 2136 // Any interface-specific records we're going to send are marked as being sent on all appropriate interfaces (which is just one) 2137 // Eligible records that are more than half-way to their announcement time are accelerated 2138 for (rr = m->ResourceRecords; rr; rr=rr->next) 2139 if ((rr->resrec.InterfaceID && rr->ImmedAnswer) || 2140 (rr->ThisAPInterval <= maxExistingAnnounceInterval && 2141 TimeToAnnounceThisRecord(rr, m->timenow + rr->ThisAPInterval/2) && 2142 !rr->AddressProxy.type && // Don't include ARP Annoucements when considering which records to accelerate 2143 ResourceRecordIsValidAnswer(rr))) 2144 rr->ImmedAnswer = mDNSInterfaceMark; // Send on all interfaces 2145 2146 // When sending SRV records (particularly when announcing a new service) automatically add related Address record(s) as additionals 2147 // Note: Currently all address records are interface-specific, so it's safe to set ImmedAdditional to their InterfaceID, 2148 // which will be non-null. If by some chance there is an address record that's not interface-specific (should never happen) 2149 // then all that means is that it won't get sent -- which would not be the end of the world. 2150 for (rr = m->ResourceRecords; rr; rr=rr->next) 2151 { 2152 if (rr->ImmedAnswer && rr->resrec.rrtype == kDNSType_SRV) 2153 for (r2=m->ResourceRecords; r2; r2=r2->next) // Scan list of resource records 2154 if (RRTypeIsAddressType(r2->resrec.rrtype) && // For all address records (A/AAAA) ... 2155 ResourceRecordIsValidAnswer(r2) && // ... which are valid for answer ... 2156 rr->LastMCTime - r2->LastMCTime >= 0 && // ... which we have not sent recently ... 2157 rr->resrec.rdatahash == r2->resrec.namehash && // ... whose name is the name of the SRV target 2158 SameDomainName(&rr->resrec.rdata->u.srv.target, r2->resrec.name) && 2159 (rr->ImmedAnswer == mDNSInterfaceMark || rr->ImmedAnswer == r2->resrec.InterfaceID)) 2160 r2->ImmedAdditional = r2->resrec.InterfaceID; // ... then mark this address record for sending too 2161 // We also make sure we send the DeviceInfo TXT record too, if necessary 2162 // We check for RecordType == kDNSRecordTypeShared because we don't want to tag the 2163 // DeviceInfo TXT record onto a goodbye packet (RecordType == kDNSRecordTypeDeregistering). 2164 if (rr->ImmedAnswer && rr->resrec.RecordType == kDNSRecordTypeShared && rr->resrec.rrtype == kDNSType_PTR) 2165 if (ResourceRecordIsValidAnswer(&m->DeviceInfo) && SameDomainLabel(rr->resrec.rdata->u.name.c, m->DeviceInfo.resrec.name->c)) 2166 { 2167 if (!m->DeviceInfo.ImmedAnswer) m->DeviceInfo.ImmedAnswer = rr->ImmedAnswer; 2168 else m->DeviceInfo.ImmedAnswer = mDNSInterfaceMark; 2169 } 2170 } 2171 2172 // If there's a record which is supposed to be unique that we're going to send, then make sure that we give 2173 // the whole RRSet as an atomic unit. That means that if we have any other records with the same name/type/class 2174 // then we need to mark them for sending too. Otherwise, if we set the kDNSClass_UniqueRRSet bit on a 2175 // record, then other RRSet members that have not been sent recently will get flushed out of client caches. 2176 // -- 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 2177 // -- If any record is marked to be sent on all interfaces, make sure the whole set is marked to be sent on all interfaces 2178 for (rr = m->ResourceRecords; rr; rr=rr->next) 2179 if (rr->resrec.RecordType & kDNSRecordTypeUniqueMask) 2180 { 2181 if (rr->ImmedAnswer) // If we're sending this as answer, see that its whole RRSet is similarly marked 2182 { 2183 for (r2 = m->ResourceRecords; r2; r2=r2->next) 2184 if (ResourceRecordIsValidAnswer(r2)) 2185 if (r2->ImmedAnswer != mDNSInterfaceMark && 2186 r2->ImmedAnswer != rr->ImmedAnswer && SameResourceRecordSignature(r2, rr)) 2187 r2->ImmedAnswer = !r2->ImmedAnswer ? rr->ImmedAnswer : mDNSInterfaceMark; 2188 } 2189 else if (rr->ImmedAdditional) // If we're sending this as additional, see that its whole RRSet is similarly marked 2190 { 2191 for (r2 = m->ResourceRecords; r2; r2=r2->next) 2192 if (ResourceRecordIsValidAnswer(r2)) 2193 if (r2->ImmedAdditional != rr->ImmedAdditional && SameResourceRecordSignature(r2, rr)) 2194 r2->ImmedAdditional = rr->ImmedAdditional; 2195 } 2196 } 2197 2198 // Now set SendRNow state appropriately 2199 for (rr = m->ResourceRecords; rr; rr=rr->next) 2200 { 2201 if (rr->ImmedAnswer == mDNSInterfaceMark) // Sending this record on all appropriate interfaces 2202 { 2203 rr->SendRNow = !intf ? mDNSNULL : (rr->resrec.InterfaceID) ? rr->resrec.InterfaceID : intf->InterfaceID; 2204 rr->ImmedAdditional = mDNSNULL; // No need to send as additional if sending as answer 2205 rr->LastMCTime = m->timenow; 2206 rr->LastMCInterface = rr->ImmedAnswer; 2207 // If we're announcing this record, and it's at least half-way to its ordained time, then consider this announcement done 2208 if (TimeToAnnounceThisRecord(rr, m->timenow + rr->ThisAPInterval/2)) 2209 { 2210 rr->AnnounceCount--; 2211 if (rr->resrec.RecordType != kDNSRecordTypeDeregistering) 2212 rr->ThisAPInterval *= 2; 2213 rr->LastAPTime = m->timenow; 2214 debugf("Announcing %##s (%s) %d", rr->resrec.name->c, DNSTypeName(rr->resrec.rrtype), rr->AnnounceCount); 2215 } 2216 } 2217 else if (rr->ImmedAnswer) // Else, just respond to a single query on single interface: 2218 { 2219 rr->SendRNow = rr->ImmedAnswer; // Just respond on that interface 2220 rr->ImmedAdditional = mDNSNULL; // No need to send as additional too 2221 rr->LastMCTime = m->timenow; 2222 rr->LastMCInterface = rr->ImmedAnswer; 2223 } 2224 SetNextAnnounceProbeTime(m, rr); 2225 //if (rr->SendRNow) LogMsg("%-15.4a %s", &rr->v4Requester, ARDisplayString(m, rr)); 2226 } 2227 2228 // *** 2229 // *** 2. Loop through interface list, sending records as appropriate 2230 // *** 2231 2232 while (intf) 2233 { 2234 const int OwnerRecordSpace = (m->AnnounceOwner && intf->MAC.l[0]) ? DNSOpt_Header_Space + DNSOpt_Owner_Space(&m->PrimaryMAC, &intf->MAC) : 0; 2235 int numDereg = 0; 2236 int numAnnounce = 0; 2237 int numAnswer = 0; 2238 mDNSu8 *responseptr = m->omsg.data; 2239 mDNSu8 *newptr; 2240 InitializeDNSMessage(&m->omsg.h, zeroID, ResponseFlags); 2241 2242 // First Pass. Look for: 2243 // 1. Deregistering records that need to send their goodbye packet 2244 // 2. Updated records that need to retract their old data 2245 // 3. Answers and announcements we need to send 2246 for (rr = m->ResourceRecords; rr; rr=rr->next) 2247 { 2248 2249 // Skip this interface if the record InterfaceID is *Any and the record is not 2250 // appropriate for the interface type. 2251 if ((rr->SendRNow == intf->InterfaceID) && 2252 ((rr->resrec.InterfaceID == mDNSInterface_Any) && !mDNSPlatformValidRecordForInterface(rr, intf))) 2253 { 2254 LogInfo("SendResponses: Not sending %s, on %s", ARDisplayString(m, rr), InterfaceNameForID(m, rr->SendRNow)); 2255 rr->SendRNow = GetNextActiveInterfaceID(intf); 2256 } 2257 else if (rr->SendRNow == intf->InterfaceID) 2258 { 2259 RData *OldRData = rr->resrec.rdata; 2260 mDNSu16 oldrdlength = rr->resrec.rdlength; 2261 mDNSu8 active = (mDNSu8) 2262 (rr->resrec.RecordType != kDNSRecordTypeDeregistering && 2263 (m->SleepState != SleepState_Sleeping || intf->SPSAddr[0].type || intf->SPSAddr[1].type || intf->SPSAddr[2].type)); 2264 newptr = mDNSNULL; 2265 if (rr->NewRData && active) 2266 { 2267 // See if we should send a courtesy "goodbye" for the old data before we replace it. 2268 if (ResourceRecordIsValidAnswer(rr) && rr->resrec.RecordType == kDNSRecordTypeShared && rr->RequireGoodbye) 2269 { 2270 newptr = PutRR_OS_TTL(responseptr, &m->omsg.h.numAnswers, &rr->resrec, 0); 2271 if (newptr) { responseptr = newptr; numDereg++; rr->RequireGoodbye = mDNSfalse; } 2272 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 2273 } 2274 SetNewRData(&rr->resrec, rr->NewRData, rr->newrdlength); 2275 } 2276 2277 if (rr->resrec.RecordType & kDNSRecordTypeUniqueMask) 2278 rr->resrec.rrclass |= kDNSClass_UniqueRRSet; // Temporarily set the cache flush bit so PutResourceRecord will set it 2279 newptr = PutRR_OS_TTL(responseptr, &m->omsg.h.numAnswers, &rr->resrec, active ? rr->resrec.rroriginalttl : 0); 2280 rr->resrec.rrclass &= ~kDNSClass_UniqueRRSet; // Make sure to clear cache flush bit back to normal state 2281 if (newptr) 2282 { 2283 responseptr = newptr; 2284 rr->RequireGoodbye = active; 2285 if (rr->resrec.RecordType == kDNSRecordTypeDeregistering) numDereg++; 2286 else if (rr->LastAPTime == m->timenow) numAnnounce++; else numAnswer++; 2287 } 2288 2289 if (rr->NewRData && active) 2290 SetNewRData(&rr->resrec, OldRData, oldrdlength); 2291 2292 // The first time through (pktcount==0), if this record is verified unique 2293 // (i.e. typically A, AAAA, SRV, TXT and reverse-mapping PTR), set the flag to add an NSEC too. 2294 if (!pktcount && active && (rr->resrec.RecordType & kDNSRecordTypeActiveUniqueMask) && !rr->SendNSECNow) 2295 rr->SendNSECNow = mDNSInterfaceMark; 2296 2297 if (newptr) // If succeeded in sending, advance to next interface 2298 { 2299 // If sending on all interfaces, go to next interface; else we're finished now 2300 if (rr->ImmedAnswer == mDNSInterfaceMark && rr->resrec.InterfaceID == mDNSInterface_Any) 2301 rr->SendRNow = GetNextActiveInterfaceID(intf); 2302 else 2303 rr->SendRNow = mDNSNULL; 2304 } 2305 } 2306 } 2307 2308 // Second Pass. Add additional records, if there's space. 2309 newptr = responseptr; 2310 for (rr = m->ResourceRecords; rr; rr=rr->next) 2311 if (rr->ImmedAdditional == intf->InterfaceID) 2312 if (ResourceRecordIsValidAnswer(rr)) 2313 { 2314 // If we have at least one answer already in the packet, then plan to add additionals too 2315 mDNSBool SendAdditional = (m->omsg.h.numAnswers > 0); 2316 2317 // If we're not planning to send any additionals, but this record is a unique one, then 2318 // make sure we haven't already sent any other members of its RRSet -- if we have, then they 2319 // will have had the cache flush bit set, so now we need to finish the job and send the rest. 2320 if (!SendAdditional && (rr->resrec.RecordType & kDNSRecordTypeUniqueMask)) 2321 { 2322 const AuthRecord *a; 2323 for (a = m->ResourceRecords; a; a=a->next) 2324 if (a->LastMCTime == m->timenow && 2325 a->LastMCInterface == intf->InterfaceID && 2326 SameResourceRecordSignature(a, rr)) { SendAdditional = mDNStrue; break; } 2327 } 2328 if (!SendAdditional) // If we don't want to send this after all, 2329 rr->ImmedAdditional = mDNSNULL; // then cancel its ImmedAdditional field 2330 else if (newptr) // Else, try to add it if we can 2331 { 2332 // The first time through (pktcount==0), if this record is verified unique 2333 // (i.e. typically A, AAAA, SRV, TXT and reverse-mapping PTR), set the flag to add an NSEC too. 2334 if (!pktcount && (rr->resrec.RecordType & kDNSRecordTypeActiveUniqueMask) && !rr->SendNSECNow) 2335 rr->SendNSECNow = mDNSInterfaceMark; 2336 2337 if (rr->resrec.RecordType & kDNSRecordTypeUniqueMask) 2338 rr->resrec.rrclass |= kDNSClass_UniqueRRSet; // Temporarily set the cache flush bit so PutResourceRecord will set it 2339 newptr = PutRR_OS(newptr, &m->omsg.h.numAdditionals, &rr->resrec); 2340 rr->resrec.rrclass &= ~kDNSClass_UniqueRRSet; // Make sure to clear cache flush bit back to normal state 2341 if (newptr) 2342 { 2343 responseptr = newptr; 2344 rr->ImmedAdditional = mDNSNULL; 2345 rr->RequireGoodbye = mDNStrue; 2346 // If we successfully put this additional record in the packet, we record LastMCTime & LastMCInterface. 2347 // This matters particularly in the case where we have more than one IPv6 (or IPv4) address, because otherwise, 2348 // when we see our own multicast with the cache flush bit set, if we haven't set LastMCTime, then we'll get 2349 // all concerned and re-announce our record again to make sure it doesn't get flushed from peer caches. 2350 rr->LastMCTime = m->timenow; 2351 rr->LastMCInterface = intf->InterfaceID; 2352 } 2353 } 2354 } 2355 2356 // Third Pass. Add NSEC records, if there's space. 2357 // When we're generating an NSEC record in response to a specify query for that type 2358 // (recognized by rr->SendNSECNow == intf->InterfaceID) we should really put the NSEC in the Answer Section, 2359 // not Additional Section, but for now it's easier to handle both cases in this Additional Section loop here. 2360 for (rr = m->ResourceRecords; rr; rr=rr->next) 2361 if (rr->SendNSECNow == mDNSInterfaceMark || rr->SendNSECNow == intf->InterfaceID) 2362 { 2363 AuthRecord nsec; 2364 mDNS_SetupResourceRecord(&nsec, mDNSNULL, mDNSInterface_Any, kDNSType_NSEC, rr->resrec.rroriginalttl, kDNSRecordTypeUnique, AuthRecordAny, mDNSNULL, mDNSNULL); 2365 nsec.resrec.rrclass |= kDNSClass_UniqueRRSet; 2366 AssignDomainName(&nsec.namestorage, rr->resrec.name); 2367 mDNSPlatformMemZero(nsec.rdatastorage.u.nsec.bitmap, sizeof(nsec.rdatastorage.u.nsec.bitmap)); 2368 for (r2 = m->ResourceRecords; r2; r2=r2->next) 2369 if (ResourceRecordIsValidAnswer(r2) && SameResourceRecordNameClassInterface(r2, rr)) 2370 { 2371 if (r2->resrec.rrtype >= kDNSQType_ANY) { LogMsg("Can't create NSEC for record %s", ARDisplayString(m, r2)); break; } 2372 else nsec.rdatastorage.u.nsec.bitmap[r2->resrec.rrtype >> 3] |= 128 >> (r2->resrec.rrtype & 7); 2373 } 2374 newptr = responseptr; 2375 if (!r2) // If we successfully built our NSEC record, add it to the packet now 2376 { 2377 newptr = PutRR_OS(responseptr, &m->omsg.h.numAdditionals, &nsec.resrec); 2378 if (newptr) responseptr = newptr; 2379 } 2380 2381 // If we successfully put the NSEC record, clear the SendNSECNow flag 2382 // If we consider this NSEC optional, then we unconditionally clear the SendNSECNow flag, even if we fail to put this additional record 2383 if (newptr || rr->SendNSECNow == mDNSInterfaceMark) 2384 { 2385 rr->SendNSECNow = mDNSNULL; 2386 // Run through remainder of list clearing SendNSECNow flag for all other records which would generate the same NSEC 2387 for (r2 = rr->next; r2; r2=r2->next) 2388 if (SameResourceRecordNameClassInterface(r2, rr)) 2389 if (r2->SendNSECNow == mDNSInterfaceMark || r2->SendNSECNow == intf->InterfaceID) 2390 r2->SendNSECNow = mDNSNULL; 2391 } 2392 } 2393 2394 if (m->omsg.h.numAnswers || m->omsg.h.numAdditionals) 2395 { 2396 // If we have data to send, add OWNER option if necessary, then send packet 2397 2398 if (OwnerRecordSpace) 2399 { 2400 AuthRecord opt; 2401 mDNS_SetupResourceRecord(&opt, mDNSNULL, mDNSInterface_Any, kDNSType_OPT, kStandardTTL, kDNSRecordTypeKnownUnique, AuthRecordAny, mDNSNULL, mDNSNULL); 2402 opt.resrec.rrclass = NormalMaxDNSMessageData; 2403 opt.resrec.rdlength = sizeof(rdataOPT); // One option in this OPT record 2404 opt.resrec.rdestimate = sizeof(rdataOPT); 2405 SetupOwnerOpt(m, intf, &opt.resrec.rdata->u.opt[0]); 2406 newptr = PutResourceRecord(&m->omsg, responseptr, &m->omsg.h.numAdditionals, &opt.resrec); 2407 if (newptr) { responseptr = newptr; LogSPS("SendResponses put %s", ARDisplayString(m, &opt)); } 2408 else if (m->omsg.h.numAnswers + m->omsg.h.numAuthorities + m->omsg.h.numAdditionals == 1) 2409 LogSPS("SendResponses: No space in packet for Owner OPT record (%d/%d/%d/%d) %s", 2410 m->omsg.h.numQuestions, m->omsg.h.numAnswers, m->omsg.h.numAuthorities, m->omsg.h.numAdditionals, ARDisplayString(m, &opt)); 2411 else 2412 LogMsg("SendResponses: How did we fail to have space for Owner OPT record (%d/%d/%d/%d) %s", 2413 m->omsg.h.numQuestions, m->omsg.h.numAnswers, m->omsg.h.numAuthorities, m->omsg.h.numAdditionals, ARDisplayString(m, &opt)); 2414 } 2415 2416 debugf("SendResponses: Sending %d Deregistration%s, %d Announcement%s, %d Answer%s, %d Additional%s on %p", 2417 numDereg, numDereg == 1 ? "" : "s", 2418 numAnnounce, numAnnounce == 1 ? "" : "s", 2419 numAnswer, numAnswer == 1 ? "" : "s", 2420 m->omsg.h.numAdditionals, m->omsg.h.numAdditionals == 1 ? "" : "s", intf->InterfaceID); 2421 2422 if (intf->IPv4Available) mDNSSendDNSMessage(m, &m->omsg, responseptr, intf->InterfaceID, mDNSNULL, &AllDNSLinkGroup_v4, MulticastDNSPort, mDNSNULL, mDNSNULL); 2423 if (intf->IPv6Available) mDNSSendDNSMessage(m, &m->omsg, responseptr, intf->InterfaceID, mDNSNULL, &AllDNSLinkGroup_v6, MulticastDNSPort, mDNSNULL, mDNSNULL); 2424 if (!m->SuppressSending) m->SuppressSending = NonZeroTime(m->timenow + (mDNSPlatformOneSecond+9)/10); 2425 if (++pktcount >= 1000) { LogMsg("SendResponses exceeded loop limit %d: giving up", pktcount); break; } 2426 // There might be more things to send on this interface, so go around one more time and try again. 2427 } 2428 else // Nothing more to send on this interface; go to next 2429 { 2430 const NetworkInterfaceInfo *next = GetFirstActiveInterface(intf->next); 2431 #if MDNS_DEBUGMSGS && 0 2432 const char *const msg = next ? "SendResponses: Nothing more on %p; moving to %p" : "SendResponses: Nothing more on %p"; 2433 debugf(msg, intf, next); 2434 #endif 2435 intf = next; 2436 pktcount = 0; // When we move to a new interface, reset packet count back to zero -- NSEC generation logic uses it 2437 } 2438 } 2439 2440 // *** 2441 // *** 3. Cleanup: Now that everything is sent, call client callback functions, and reset state variables 2442 // *** 2443 2444 if (m->CurrentRecord) 2445 LogMsg("SendResponses ERROR m->CurrentRecord already set %s", ARDisplayString(m, m->CurrentRecord)); 2446 m->CurrentRecord = m->ResourceRecords; 2447 while (m->CurrentRecord) 2448 { 2449 rr = m->CurrentRecord; 2450 m->CurrentRecord = rr->next; 2451 2452 if (rr->SendRNow) 2453 { 2454 if (rr->ARType != AuthRecordLocalOnly && rr->ARType != AuthRecordP2P) 2455 LogMsg("SendResponses: No active interface %p to send: %p %02X %s", rr->SendRNow, rr->resrec.InterfaceID, rr->resrec.RecordType, ARDisplayString(m, rr)); 2456 rr->SendRNow = mDNSNULL; 2457 } 2458 2459 if (rr->ImmedAnswer || rr->resrec.RecordType == kDNSRecordTypeDeregistering) 2460 { 2461 if (rr->NewRData) CompleteRDataUpdate(m, rr); // Update our rdata, clear the NewRData pointer, and return memory to the client 2462 2463 if (rr->resrec.RecordType == kDNSRecordTypeDeregistering && rr->AnnounceCount == 0) 2464 { 2465 // For Unicast, when we get the response from the server, we will call CompleteDeregistration 2466 if (!AuthRecord_uDNS(rr)) CompleteDeregistration(m, rr); // Don't touch rr after this 2467 } 2468 else 2469 { 2470 rr->ImmedAnswer = mDNSNULL; 2471 rr->ImmedUnicast = mDNSfalse; 2472 rr->v4Requester = zerov4Addr; 2473 rr->v6Requester = zerov6Addr; 2474 } 2475 } 2476 } 2477 verbosedebugf("SendResponses: Next in %ld ticks", m->NextScheduledResponse - m->timenow); 2478 } 2479 2480 // Calling CheckCacheExpiration() is an expensive operation because it has to look at the entire cache, 2481 // so we want to be lazy about how frequently we do it. 2482 // 1. If a cache record is currently referenced by *no* active questions, 2483 // then we don't mind expiring it up to a minute late (who will know?) 2484 // 2. Else, if a cache record is due for some of its final expiration queries, 2485 // we'll allow them to be late by up to 2% of the TTL 2486 // 3. Else, if a cache record has completed all its final expiration queries without success, 2487 // and is expiring, and had an original TTL more than ten seconds, we'll allow it to be one second late 2488 // 4. Else, it is expiring and had an original TTL of ten seconds or less (includes explicit goodbye packets), 2489 // so allow at most 1/10 second lateness 2490 // 5. For records with rroriginalttl set to zero, that means we really want to delete them immediately 2491 // (we have a new record with DelayDelivery set, waiting for the old record to go away before we can notify clients). 2492 #define CacheCheckGracePeriod(RR) ( \ 2493 ((RR)->CRActiveQuestion == mDNSNULL ) ? (60 * mDNSPlatformOneSecond) : \ 2494 ((RR)->UnansweredQueries < MaxUnansweredQueries) ? (TicksTTL(rr)/50) : \ 2495 ((RR)->resrec.rroriginalttl > 10 ) ? (mDNSPlatformOneSecond) : \ 2496 ((RR)->resrec.rroriginalttl > 0 ) ? (mDNSPlatformOneSecond/10) : 0) 2497 2498 #define NextCacheCheckEvent(RR) ((RR)->NextRequiredQuery + CacheCheckGracePeriod(RR)) 2499 2500 mDNSexport void ScheduleNextCacheCheckTime(mDNS *const m, const mDNSu32 slot, const mDNSs32 event) 2501 { 2502 if (m->rrcache_nextcheck[slot] - event > 0) 2503 m->rrcache_nextcheck[slot] = event; 2504 if (m->NextCacheCheck - event > 0) 2505 m->NextCacheCheck = event; 2506 } 2507 2508 // Note: MUST call SetNextCacheCheckTimeForRecord any time we change: 2509 // rr->TimeRcvd 2510 // rr->resrec.rroriginalttl 2511 // rr->UnansweredQueries 2512 // rr->CRActiveQuestion 2513 mDNSlocal void SetNextCacheCheckTimeForRecord(mDNS *const m, CacheRecord *const rr) 2514 { 2515 rr->NextRequiredQuery = RRExpireTime(rr); 2516 2517 // If we have an active question, then see if we want to schedule a refresher query for this record. 2518 // Usually we expect to do four queries, at 80-82%, 85-87%, 90-92% and then 95-97% of the TTL. 2519 if (rr->CRActiveQuestion && rr->UnansweredQueries < MaxUnansweredQueries) 2520 { 2521 rr->NextRequiredQuery -= TicksTTL(rr)/20 * (MaxUnansweredQueries - rr->UnansweredQueries); 2522 rr->NextRequiredQuery += mDNSRandom((mDNSu32)TicksTTL(rr)/50); 2523 verbosedebugf("SetNextCacheCheckTimeForRecord: NextRequiredQuery in %ld sec CacheCheckGracePeriod %d ticks for %s", 2524 (rr->NextRequiredQuery - m->timenow) / mDNSPlatformOneSecond, CacheCheckGracePeriod(rr), CRDisplayString(m,rr)); 2525 } 2526 2527 ScheduleNextCacheCheckTime(m, HashSlot(rr->resrec.name), NextCacheCheckEvent(rr)); 2528 } 2529 2530 #define kMinimumReconfirmTime ((mDNSu32)mDNSPlatformOneSecond * 5) 2531 #define kDefaultReconfirmTimeForWake ((mDNSu32)mDNSPlatformOneSecond * 5) 2532 #define kDefaultReconfirmTimeForNoAnswer ((mDNSu32)mDNSPlatformOneSecond * 5) 2533 #define kDefaultReconfirmTimeForFlappingInterface ((mDNSu32)mDNSPlatformOneSecond * 30) 2534 2535 mDNSlocal mStatus mDNS_Reconfirm_internal(mDNS *const m, CacheRecord *const rr, mDNSu32 interval) 2536 { 2537 if (interval < kMinimumReconfirmTime) 2538 interval = kMinimumReconfirmTime; 2539 if (interval > 0x10000000) // Make sure interval doesn't overflow when we multiply by four below 2540 interval = 0x10000000; 2541 2542 // If the expected expiration time for this record is more than interval+33%, then accelerate its expiration 2543 if (RRExpireTime(rr) - m->timenow > (mDNSs32)((interval * 4) / 3)) 2544 { 2545 // Add a 33% random amount to the interval, to avoid synchronization between multiple hosts 2546 // For all the reconfirmations in a given batch, we want to use the same random value 2547 // so that the reconfirmation questions can be grouped into a single query packet 2548 if (!m->RandomReconfirmDelay) m->RandomReconfirmDelay = 1 + mDNSRandom(0x3FFFFFFF); 2549 interval += m->RandomReconfirmDelay % ((interval/3) + 1); 2550 rr->TimeRcvd = m->timenow - (mDNSs32)interval * 3; 2551 rr->resrec.rroriginalttl = (interval * 4 + mDNSPlatformOneSecond - 1) / mDNSPlatformOneSecond; 2552 SetNextCacheCheckTimeForRecord(m, rr); 2553 } 2554 debugf("mDNS_Reconfirm_internal:%6ld ticks to go for %s %p", 2555 RRExpireTime(rr) - m->timenow, CRDisplayString(m, rr), rr->CRActiveQuestion); 2556 return(mStatus_NoError); 2557 } 2558 2559 #define MaxQuestionInterval (3600 * mDNSPlatformOneSecond) 2560 2561 // BuildQuestion puts a question into a DNS Query packet and if successful, updates the value of queryptr. 2562 // It also appends to the list of known answer records that need to be included, 2563 // and updates the forcast for the size of the known answer section. 2564 mDNSlocal mDNSBool BuildQuestion(mDNS *const m, DNSMessage *query, mDNSu8 **queryptr, DNSQuestion *q, 2565 CacheRecord ***kalistptrptr, mDNSu32 *answerforecast) 2566 { 2567 mDNSBool ucast = (q->LargeAnswers || q->RequestUnicast) && m->CanReceiveUnicastOn5353; 2568 mDNSu16 ucbit = (mDNSu16)(ucast ? kDNSQClass_UnicastResponse : 0); 2569 const mDNSu8 *const limit = query->data + NormalMaxDNSMessageData; 2570 mDNSu8 *newptr = putQuestion(query, *queryptr, limit - *answerforecast, &q->qname, q->qtype, (mDNSu16)(q->qclass | ucbit)); 2571 if (!newptr) 2572 { 2573 debugf("BuildQuestion: No more space in this packet for question %##s (%s)", q->qname.c, DNSTypeName(q->qtype)); 2574 return(mDNSfalse); 2575 } 2576 else 2577 { 2578 mDNSu32 forecast = *answerforecast; 2579 const mDNSu32 slot = HashSlot(&q->qname); 2580 const CacheGroup *const cg = CacheGroupForName(m, slot, q->qnamehash, &q->qname); 2581 CacheRecord *rr; 2582 CacheRecord **ka = *kalistptrptr; // Make a working copy of the pointer we're going to update 2583 2584 for (rr = cg ? cg->members : mDNSNULL; rr; rr=rr->next) // If we have a resource record in our cache, 2585 if (rr->resrec.InterfaceID == q->SendQNow && // received on this interface 2586 !(rr->resrec.RecordType & kDNSRecordTypeUniqueMask) && // which is a shared (i.e. not unique) record type 2587 rr->NextInKAList == mDNSNULL && ka != &rr->NextInKAList && // which is not already in the known answer list 2588 rr->resrec.rdlength <= SmallRecordLimit && // which is small enough to sensibly fit in the packet 2589 SameNameRecordAnswersQuestion(&rr->resrec, q) && // which answers our question 2590 rr->TimeRcvd + TicksTTL(rr)/2 - m->timenow > // and its half-way-to-expiry time is at least 1 second away 2591 mDNSPlatformOneSecond) // (also ensures we never include goodbye records with TTL=1) 2592 { 2593 // We don't want to include unique records in the Known Answer section. The Known Answer section 2594 // is intended to suppress floods of shared-record replies from many other devices on the network. 2595 // That concept really does not apply to unique records, and indeed if we do send a query for 2596 // which we have a unique record already in our cache, then including that unique record as a 2597 // Known Answer, so as to suppress the only answer we were expecting to get, makes little sense. 2598 2599 *ka = rr; // Link this record into our known answer chain 2600 ka = &rr->NextInKAList; 2601 // We forecast: compressed name (2) type (2) class (2) TTL (4) rdlength (2) rdata (n) 2602 forecast += 12 + rr->resrec.rdestimate; 2603 // If we're trying to put more than one question in this packet, and it doesn't fit 2604 // then undo that last question and try again next time 2605 if (query->h.numQuestions > 1 && newptr + forecast >= limit) 2606 { 2607 debugf("BuildQuestion: Retracting question %##s (%s) new forecast total %d", 2608 q->qname.c, DNSTypeName(q->qtype), newptr + forecast - query->data); 2609 query->h.numQuestions--; 2610 ka = *kalistptrptr; // Go back to where we started and retract these answer records 2611 while (*ka) { CacheRecord *c = *ka; *ka = mDNSNULL; ka = &c->NextInKAList; } 2612 return(mDNSfalse); // Return false, so we'll try again in the next packet 2613 } 2614 } 2615 2616 // Success! Update our state pointers, increment UnansweredQueries as appropriate, and return 2617 *queryptr = newptr; // Update the packet pointer 2618 *answerforecast = forecast; // Update the forecast 2619 *kalistptrptr = ka; // Update the known answer list pointer 2620 if (ucast) q->ExpectUnicastResp = NonZeroTime(m->timenow); 2621 2622 for (rr = cg ? cg->members : mDNSNULL; rr; rr=rr->next) // For every resource record in our cache, 2623 if (rr->resrec.InterfaceID == q->SendQNow && // received on this interface 2624 rr->NextInKAList == mDNSNULL && ka != &rr->NextInKAList && // which is not in the known answer list 2625 SameNameRecordAnswersQuestion(&rr->resrec, q)) // which answers our question 2626 { 2627 rr->UnansweredQueries++; // indicate that we're expecting a response 2628 rr->LastUnansweredTime = m->timenow; 2629 SetNextCacheCheckTimeForRecord(m, rr); 2630 } 2631 2632 return(mDNStrue); 2633 } 2634 } 2635 2636 // When we have a query looking for a specified name, but there appear to be no answers with 2637 // that name, ReconfirmAntecedents() is called with depth=0 to start the reconfirmation process 2638 // for any records in our cache that reference the given name (e.g. PTR and SRV records). 2639 // For any such cache record we find, we also recursively call ReconfirmAntecedents() for *its* name. 2640 // We increment depth each time we recurse, to guard against possible infinite loops, with a limit of 5. 2641 // A typical reconfirmation scenario might go like this: 2642 // Depth 0: Name "myhost.local" has no address records 2643 // Depth 1: SRV "My Service._example._tcp.local." refers to "myhost.local"; may be stale 2644 // Depth 2: PTR "_example._tcp.local." refers to "My Service"; may be stale 2645 // Depth 3: PTR "_services._dns-sd._udp.local." refers to "_example._tcp.local."; may be stale 2646 // Currently depths 4 and 5 are not expected to occur; if we did get to depth 5 we'd reconfim any records we 2647 // found referring to the given name, but not recursively descend any further reconfirm *their* antecedents. 2648 mDNSlocal void ReconfirmAntecedents(mDNS *const m, const domainname *const name, const mDNSu32 namehash, const int depth) 2649 { 2650 mDNSu32 slot; 2651 CacheGroup *cg; 2652 CacheRecord *cr; 2653 debugf("ReconfirmAntecedents (depth=%d) for %##s", depth, name->c); 2654 FORALL_CACHERECORDS(slot, cg, cr) 2655 { 2656 domainname *crtarget = GetRRDomainNameTarget(&cr->resrec); 2657 if (crtarget && cr->resrec.rdatahash == namehash && SameDomainName(crtarget, name)) 2658 { 2659 LogInfo("ReconfirmAntecedents: Reconfirming (depth=%d) %s", depth, CRDisplayString(m, cr)); 2660 mDNS_Reconfirm_internal(m, cr, kDefaultReconfirmTimeForNoAnswer); 2661 if (depth < 5) ReconfirmAntecedents(m, cr->resrec.name, cr->resrec.namehash, depth+1); 2662 } 2663 } 2664 } 2665 2666 // If we get no answer for a AAAA query, then before doing an automatic implicit ReconfirmAntecedents 2667 // we check if we have an address record for the same name. If we do have an IPv4 address for a given 2668 // name but not an IPv6 address, that's okay (it just means the device doesn't do IPv6) so the failure 2669 // to get a AAAA response is not grounds to doubt the PTR/SRV chain that lead us to that name. 2670 mDNSlocal const CacheRecord *CacheHasAddressTypeForName(mDNS *const m, const domainname *const name, const mDNSu32 namehash) 2671 { 2672 CacheGroup *const cg = CacheGroupForName(m, HashSlot(name), namehash, name); 2673 const CacheRecord *cr = cg ? cg->members : mDNSNULL; 2674 while (cr && !RRTypeIsAddressType(cr->resrec.rrtype)) cr=cr->next; 2675 return(cr); 2676 } 2677 2678 mDNSlocal const CacheRecord *FindSPSInCache1(mDNS *const m, const DNSQuestion *const q, const CacheRecord *const c0, const CacheRecord *const c1) 2679 { 2680 CacheGroup *const cg = CacheGroupForName(m, HashSlot(&q->qname), q->qnamehash, &q->qname); 2681 const CacheRecord *cr, *bestcr = mDNSNULL; 2682 mDNSu32 bestmetric = 1000000; 2683 for (cr = cg ? cg->members : mDNSNULL; cr; cr=cr->next) 2684 if (cr->resrec.rrtype == kDNSType_PTR && cr->resrec.rdlength >= 6) // If record is PTR type, with long enough name, 2685 if (cr != c0 && cr != c1) // that's not one we've seen before, 2686 if (SameNameRecordAnswersQuestion(&cr->resrec, q)) // and answers our browse query, 2687 if (!IdenticalSameNameRecord(&cr->resrec, &m->SPSRecords.RR_PTR.resrec)) // and is not our own advertised service... 2688 { 2689 mDNSu32 metric = SPSMetric(cr->resrec.rdata->u.name.c); 2690 if (bestmetric > metric) { bestmetric = metric; bestcr = cr; } 2691 } 2692 return(bestcr); 2693 } 2694 2695 // Finds the three best Sleep Proxies we currently have in our cache 2696 mDNSexport void FindSPSInCache(mDNS *const m, const DNSQuestion *const q, const CacheRecord *sps[3]) 2697 { 2698 sps[0] = FindSPSInCache1(m, q, mDNSNULL, mDNSNULL); 2699 sps[1] = !sps[0] ? mDNSNULL : FindSPSInCache1(m, q, sps[0], mDNSNULL); 2700 sps[2] = !sps[1] ? mDNSNULL : FindSPSInCache1(m, q, sps[0], sps[1]); 2701 } 2702 2703 // Only DupSuppressInfos newer than the specified 'time' are allowed to remain active 2704 mDNSlocal void ExpireDupSuppressInfo(DupSuppressInfo ds[DupSuppressInfoSize], mDNSs32 time) 2705 { 2706 int i; 2707 for (i=0; i<DupSuppressInfoSize; i++) if (ds[i].Time - time < 0) ds[i].InterfaceID = mDNSNULL; 2708 } 2709 2710 mDNSlocal void ExpireDupSuppressInfoOnInterface(DupSuppressInfo ds[DupSuppressInfoSize], mDNSs32 time, mDNSInterfaceID InterfaceID) 2711 { 2712 int i; 2713 for (i=0; i<DupSuppressInfoSize; i++) if (ds[i].InterfaceID == InterfaceID && ds[i].Time - time < 0) ds[i].InterfaceID = mDNSNULL; 2714 } 2715 2716 mDNSlocal mDNSBool SuppressOnThisInterface(const DupSuppressInfo ds[DupSuppressInfoSize], const NetworkInterfaceInfo * const intf) 2717 { 2718 int i; 2719 mDNSBool v4 = !intf->IPv4Available; // If this interface doesn't do v4, we don't need to find a v4 duplicate of this query 2720 mDNSBool v6 = !intf->IPv6Available; // If this interface doesn't do v6, we don't need to find a v6 duplicate of this query 2721 for (i=0; i<DupSuppressInfoSize; i++) 2722 if (ds[i].InterfaceID == intf->InterfaceID) 2723 { 2724 if (ds[i].Type == mDNSAddrType_IPv4) v4 = mDNStrue; 2725 else if (ds[i].Type == mDNSAddrType_IPv6) v6 = mDNStrue; 2726 if (v4 && v6) return(mDNStrue); 2727 } 2728 return(mDNSfalse); 2729 } 2730 2731 mDNSlocal int RecordDupSuppressInfo(DupSuppressInfo ds[DupSuppressInfoSize], mDNSs32 Time, mDNSInterfaceID InterfaceID, mDNSs32 Type) 2732 { 2733 int i, j; 2734 2735 // See if we have this one in our list somewhere already 2736 for (i=0; i<DupSuppressInfoSize; i++) if (ds[i].InterfaceID == InterfaceID && ds[i].Type == Type) break; 2737 2738 // If not, find a slot we can re-use 2739 if (i >= DupSuppressInfoSize) 2740 { 2741 i = 0; 2742 for (j=1; j<DupSuppressInfoSize && ds[i].InterfaceID; j++) 2743 if (!ds[j].InterfaceID || ds[j].Time - ds[i].Time < 0) 2744 i = j; 2745 } 2746 2747 // Record the info about this query we saw 2748 ds[i].Time = Time; 2749 ds[i].InterfaceID = InterfaceID; 2750 ds[i].Type = Type; 2751 2752 return(i); 2753 } 2754 2755 mDNSlocal void mDNSSendWakeOnResolve(mDNS *const m, DNSQuestion *q) 2756 { 2757 int len, i, cnt; 2758 mDNSInterfaceID InterfaceID = q->InterfaceID; 2759 domainname *d = &q->qname; 2760 2761 // We can't send magic packets without knowing which interface to send it on. 2762 if (InterfaceID == mDNSInterface_Any || InterfaceID == mDNSInterface_LocalOnly || InterfaceID == mDNSInterface_P2P) 2763 { 2764 LogMsg("mDNSSendWakeOnResolve: ERROR!! Invalid InterfaceID %p for question %##s", InterfaceID, q->qname.c); 2765 return; 2766 } 2767 2768 // Split MAC@IPAddress and pass them separately 2769 len = d->c[0]; 2770 i = 1; 2771 cnt = 0; 2772 for (i = 1; i < len; i++) 2773 { 2774 if (d->c[i] == '@') 2775 { 2776 char EthAddr[18]; // ethernet adddress : 12 bytes + 5 ":" + 1 NULL byte 2777 char IPAddr[47]; // Max IP address len: 46 bytes (IPv6) + 1 NULL byte 2778 if (cnt != 5) 2779 { 2780 LogMsg("mDNSSendWakeOnResolve: ERROR!! Malformed Ethernet address %##s, cnt %d", q->qname.c, cnt); 2781 return; 2782 } 2783 if ((i - 1) > (int) (sizeof(EthAddr) - 1)) 2784 { 2785 LogMsg("mDNSSendWakeOnResolve: ERROR!! Malformed Ethernet address %##s, length %d", q->qname.c, i - 1); 2786 return; 2787 } 2788 if ((len - i) > (int)(sizeof(IPAddr) - 1)) 2789 { 2790 LogMsg("mDNSSendWakeOnResolve: ERROR!! Malformed IP address %##s, length %d", q->qname.c, len - i); 2791 return; 2792 } 2793 mDNSPlatformMemCopy(EthAddr, &d->c[1], i - 1); 2794 EthAddr[i - 1] = 0; 2795 mDNSPlatformMemCopy(IPAddr, &d->c[i + 1], len - i); 2796 IPAddr[len - i] = 0; 2797 mDNSPlatformSendWakeupPacket(m, InterfaceID, EthAddr, IPAddr, InitialWakeOnResolveCount - q->WakeOnResolveCount); 2798 return; 2799 } 2800 else if (d->c[i] == ':') 2801 cnt++; 2802 } 2803 LogMsg("mDNSSendWakeOnResolve: ERROR!! Malformed WakeOnResolve name %##s", q->qname.c); 2804 } 2805 2806 2807 mDNSlocal mDNSBool AccelerateThisQuery(mDNS *const m, DNSQuestion *q) 2808 { 2809 // If more than 90% of the way to the query time, we should unconditionally accelerate it 2810 if (TimeToSendThisQuestion(q, m->timenow + q->ThisQInterval/10)) 2811 return(mDNStrue); 2812 2813 // If half-way to next scheduled query time, only accelerate if it will add less than 512 bytes to the packet 2814 if (TimeToSendThisQuestion(q, m->timenow + q->ThisQInterval/2)) 2815 { 2816 // We forecast: qname (n) type (2) class (2) 2817 mDNSu32 forecast = (mDNSu32)DomainNameLength(&q->qname) + 4; 2818 const mDNSu32 slot = HashSlot(&q->qname); 2819 const CacheGroup *const cg = CacheGroupForName(m, slot, q->qnamehash, &q->qname); 2820 const CacheRecord *rr; 2821 for (rr = cg ? cg->members : mDNSNULL; rr; rr=rr->next) // If we have a resource record in our cache, 2822 if (rr->resrec.rdlength <= SmallRecordLimit && // which is small enough to sensibly fit in the packet 2823 SameNameRecordAnswersQuestion(&rr->resrec, q) && // which answers our question 2824 rr->TimeRcvd + TicksTTL(rr)/2 - m->timenow >= 0 && // and it is less than half-way to expiry 2825 rr->NextRequiredQuery - (m->timenow + q->ThisQInterval) > 0)// and we'll ask at least once again before NextRequiredQuery 2826 { 2827 // We forecast: compressed name (2) type (2) class (2) TTL (4) rdlength (2) rdata (n) 2828 forecast += 12 + rr->resrec.rdestimate; 2829 if (forecast >= 512) return(mDNSfalse); // If this would add 512 bytes or more to the packet, don't accelerate 2830 } 2831 return(mDNStrue); 2832 } 2833 2834 return(mDNSfalse); 2835 } 2836 2837 // How Standard Queries are generated: 2838 // 1. The Question Section contains the question 2839 // 2. The Additional Section contains answers we already know, to suppress duplicate responses 2840 2841 // How Probe Queries are generated: 2842 // 1. The Question Section contains queries for the name we intend to use, with QType=ANY because 2843 // if some other host is already using *any* records with this name, we want to know about it. 2844 // 2. The Authority Section contains the proposed values we intend to use for one or more 2845 // of our records with that name (analogous to the Update section of DNS Update packets) 2846 // because if some other host is probing at the same time, we each want to know what the other is 2847 // planning, in order to apply the tie-breaking rule to see who gets to use the name and who doesn't. 2848 2849 mDNSlocal void SendQueries(mDNS *const m) 2850 { 2851 mDNSu32 slot; 2852 CacheGroup *cg; 2853 CacheRecord *cr; 2854 AuthRecord *ar; 2855 int pktcount = 0; 2856 DNSQuestion *q; 2857 // For explanation of maxExistingQuestionInterval logic, see comments for maxExistingAnnounceInterval 2858 mDNSs32 maxExistingQuestionInterval = 0; 2859 const NetworkInterfaceInfo *intf = GetFirstActiveInterface(m->HostInterfaces); 2860 CacheRecord *KnownAnswerList = mDNSNULL; 2861 2862 // 1. If time for a query, work out what we need to do 2863 2864 // We're expecting to send a query anyway, so see if any expiring cache records are close enough 2865 // to their NextRequiredQuery to be worth batching them together with this one 2866 FORALL_CACHERECORDS(slot, cg, cr) 2867 if (cr->CRActiveQuestion && cr->UnansweredQueries < MaxUnansweredQueries) 2868 if (m->timenow + TicksTTL(cr)/50 - cr->NextRequiredQuery >= 0) 2869 { 2870 debugf("Sending %d%% cache expiration query for %s", 80 + 5 * cr->UnansweredQueries, CRDisplayString(m, cr)); 2871 q = cr->CRActiveQuestion; 2872 ExpireDupSuppressInfoOnInterface(q->DupSuppress, m->timenow - TicksTTL(cr)/20, cr->resrec.InterfaceID); 2873 // For uDNS queries (TargetQID non-zero) we adjust LastQTime, 2874 // and bump UnansweredQueries so that we don't spin trying to send the same cache expiration query repeatedly 2875 if (q->Target.type) q->SendQNow = mDNSInterfaceMark; // If targeted query, mark it 2876 else if (!mDNSOpaque16IsZero(q->TargetQID)) { q->LastQTime = m->timenow - q->ThisQInterval; cr->UnansweredQueries++; } 2877 else if (q->SendQNow == mDNSNULL) q->SendQNow = cr->resrec.InterfaceID; 2878 else if (q->SendQNow != cr->resrec.InterfaceID) q->SendQNow = mDNSInterfaceMark; 2879 } 2880 2881 // Scan our list of questions to see which: 2882 // *WideArea* queries need to be sent 2883 // *unicast* queries need to be sent 2884 // *multicast* queries we're definitely going to send 2885 if (m->CurrentQuestion) 2886 LogMsg("SendQueries ERROR m->CurrentQuestion already set: %##s (%s)", m->CurrentQuestion->qname.c, DNSTypeName(m->CurrentQuestion->qtype)); 2887 m->CurrentQuestion = m->Questions; 2888 while (m->CurrentQuestion && m->CurrentQuestion != m->NewQuestions) 2889 { 2890 q = m->CurrentQuestion; 2891 if (q->Target.type && (q->SendQNow || TimeToSendThisQuestion(q, m->timenow))) 2892 { 2893 mDNSu8 *qptr = m->omsg.data; 2894 const mDNSu8 *const limit = m->omsg.data + sizeof(m->omsg.data); 2895 2896 // 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 2897 if (!q->LocalSocket) q->LocalSocket = mDNSPlatformUDPSocket(m, zeroIPPort); 2898 if (q->LocalSocket) 2899 { 2900 InitializeDNSMessage(&m->omsg.h, q->TargetQID, QueryFlags); 2901 qptr = putQuestion(&m->omsg, qptr, limit, &q->qname, q->qtype, q->qclass); 2902 mDNSSendDNSMessage(m, &m->omsg, qptr, mDNSInterface_Any, q->LocalSocket, &q->Target, q->TargetPort, mDNSNULL, mDNSNULL); 2903 q->ThisQInterval *= QuestionIntervalStep; 2904 } 2905 if (q->ThisQInterval > MaxQuestionInterval) 2906 q->ThisQInterval = MaxQuestionInterval; 2907 q->LastQTime = m->timenow; 2908 q->LastQTxTime = m->timenow; 2909 q->RecentAnswerPkts = 0; 2910 q->SendQNow = mDNSNULL; 2911 q->ExpectUnicastResp = NonZeroTime(m->timenow); 2912 } 2913 else if (mDNSOpaque16IsZero(q->TargetQID) && !q->Target.type && TimeToSendThisQuestion(q, m->timenow)) 2914 { 2915 //LogInfo("Time to send %##s (%s) %d", q->qname.c, DNSTypeName(q->qtype), m->timenow - NextQSendTime(q)); 2916 q->SendQNow = mDNSInterfaceMark; // Mark this question for sending on all interfaces 2917 if (maxExistingQuestionInterval < q->ThisQInterval) 2918 maxExistingQuestionInterval = q->ThisQInterval; 2919 } 2920 // If m->CurrentQuestion wasn't modified out from under us, advance it now 2921 // We can't do this at the start of the loop because uDNS_CheckCurrentQuestion() depends on having 2922 // m->CurrentQuestion point to the right question 2923 if (q == m->CurrentQuestion) m->CurrentQuestion = m->CurrentQuestion->next; 2924 } 2925 while (m->CurrentQuestion) 2926 { 2927 LogInfo("SendQueries question loop 1: Skipping NewQuestion %##s (%s)", m->CurrentQuestion->qname.c, DNSTypeName(m->CurrentQuestion->qtype)); 2928 m->CurrentQuestion = m->CurrentQuestion->next; 2929 } 2930 m->CurrentQuestion = mDNSNULL; 2931 2932 // Scan our list of questions 2933 // (a) to see if there are any more that are worth accelerating, and 2934 // (b) to update the state variables for *all* the questions we're going to send 2935 // Note: Don't set NextScheduledQuery until here, because uDNS_CheckCurrentQuestion in the loop above can add new questions to the list, 2936 // which causes NextScheduledQuery to get (incorrectly) set to m->timenow. Setting it here is the right place, because the very 2937 // 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. 2938 m->NextScheduledQuery = m->timenow + 0x78000000; 2939 for (q = m->Questions; q && q != m->NewQuestions; q=q->next) 2940 { 2941 if (mDNSOpaque16IsZero(q->TargetQID) && (q->SendQNow || 2942 (!q->Target.type && ActiveQuestion(q) && q->ThisQInterval <= maxExistingQuestionInterval && AccelerateThisQuery(m,q)))) 2943 { 2944 // If at least halfway to next query time, advance to next interval 2945 // If less than halfway to next query time, then 2946 // treat this as logically a repeat of the last transmission, without advancing the interval 2947 if (m->timenow - (q->LastQTime + (q->ThisQInterval/2)) >= 0) 2948 { 2949 //LogInfo("Accelerating %##s (%s) %d", q->qname.c, DNSTypeName(q->qtype), m->timenow - NextQSendTime(q)); 2950 q->SendQNow = mDNSInterfaceMark; // Mark this question for sending on all interfaces 2951 debugf("SendQueries: %##s (%s) next interval %d seconds RequestUnicast = %d", 2952 q->qname.c, DNSTypeName(q->qtype), q->ThisQInterval / InitialQuestionInterval, q->RequestUnicast); 2953 q->ThisQInterval *= QuestionIntervalStep; 2954 if (q->ThisQInterval > MaxQuestionInterval) 2955 q->ThisQInterval = MaxQuestionInterval; 2956 else if (q->CurrentAnswers == 0 && q->ThisQInterval == InitialQuestionInterval * QuestionIntervalStep3 && !q->RequestUnicast && 2957 !(RRTypeIsAddressType(q->qtype) && CacheHasAddressTypeForName(m, &q->qname, q->qnamehash))) 2958 { 2959 // Generally don't need to log this. 2960 // It's not especially noteworthy if a query finds no results -- this usually happens for domain 2961 // enumeration queries in the LL subdomain (e.g. "db._dns-sd._udp.0.0.254.169.in-addr.arpa") 2962 // and when there simply happen to be no instances of the service the client is looking 2963 // for (e.g. iTunes is set to look for RAOP devices, and the current network has none). 2964 debugf("SendQueries: Zero current answers for %##s (%s); will reconfirm antecedents", 2965 q->qname.c, DNSTypeName(q->qtype)); 2966 // Sending third query, and no answers yet; time to begin doubting the source 2967 ReconfirmAntecedents(m, &q->qname, q->qnamehash, 0); 2968 } 2969 } 2970 2971 // Mark for sending. (If no active interfaces, then don't even try.) 2972 q->SendOnAll = (q->SendQNow == mDNSInterfaceMark); 2973 if (q->SendOnAll) 2974 { 2975 q->SendQNow = !intf ? mDNSNULL : (q->InterfaceID) ? q->InterfaceID : intf->InterfaceID; 2976 q->LastQTime = m->timenow; 2977 } 2978 2979 // If we recorded a duplicate suppression for this question less than half an interval ago, 2980 // then we consider it recent enough that we don't need to do an identical query ourselves. 2981 ExpireDupSuppressInfo(q->DupSuppress, m->timenow - q->ThisQInterval/2); 2982 2983 q->LastQTxTime = m->timenow; 2984 q->RecentAnswerPkts = 0; 2985 if (q->RequestUnicast) q->RequestUnicast--; 2986 } 2987 // For all questions (not just the ones we're sending) check what the next scheduled event will be 2988 // We don't need to consider NewQuestions here because for those we'll set m->NextScheduledQuery in AnswerNewQuestion 2989 SetNextQueryTime(m,q); 2990 } 2991 2992 // 2. Scan our authoritative RR list to see what probes we might need to send 2993 2994 m->NextScheduledProbe = m->timenow + 0x78000000; 2995 2996 if (m->CurrentRecord) 2997 LogMsg("SendQueries ERROR m->CurrentRecord already set %s", ARDisplayString(m, m->CurrentRecord)); 2998 m->CurrentRecord = m->ResourceRecords; 2999 while (m->CurrentRecord) 3000 { 3001 ar = m->CurrentRecord; 3002 m->CurrentRecord = ar->next; 3003 if (!AuthRecord_uDNS(ar) && ar->resrec.RecordType == kDNSRecordTypeUnique) // For all records that are still probing... 3004 { 3005 // 1. If it's not reached its probe time, just make sure we update m->NextScheduledProbe correctly 3006 if (m->timenow - (ar->LastAPTime + ar->ThisAPInterval) < 0) 3007 { 3008 SetNextAnnounceProbeTime(m, ar); 3009 } 3010 // 2. else, if it has reached its probe time, mark it for sending and then update m->NextScheduledProbe correctly 3011 else if (ar->ProbeCount) 3012 { 3013 if (ar->AddressProxy.type == mDNSAddrType_IPv4) 3014 { 3015 LogSPS("SendQueries ARP Probe %d %s %s", ar->ProbeCount, InterfaceNameForID(m, ar->resrec.InterfaceID), ARDisplayString(m,ar)); 3016 SendARP(m, 1, ar, &zerov4Addr, &zeroEthAddr, &ar->AddressProxy.ip.v4, &ar->WakeUp.IMAC); 3017 } 3018 else if (ar->AddressProxy.type == mDNSAddrType_IPv6) 3019 { 3020 LogSPS("SendQueries NDP Probe %d %s %s", ar->ProbeCount, InterfaceNameForID(m, ar->resrec.InterfaceID), ARDisplayString(m,ar)); 3021 // IPv6 source = zero 3022 // No target hardware address 3023 // IPv6 target address is address we're probing 3024 // Ethernet destination address is Ethernet interface address of the Sleep Proxy client we're probing 3025 SendNDP(m, NDP_Sol, 0, ar, &zerov6Addr, mDNSNULL, &ar->AddressProxy.ip.v6, &ar->WakeUp.IMAC); 3026 } 3027 // Mark for sending. (If no active interfaces, then don't even try.) 3028 ar->SendRNow = (!intf || ar->WakeUp.HMAC.l[0]) ? mDNSNULL : ar->resrec.InterfaceID ? ar->resrec.InterfaceID : intf->InterfaceID; 3029 ar->LastAPTime = m->timenow; 3030 // When we have a late conflict that resets a record to probing state we use a special marker value greater 3031 // than DefaultProbeCountForTypeUnique. Here we detect that state and reset ar->ProbeCount back to the right value. 3032 if (ar->ProbeCount > DefaultProbeCountForTypeUnique) 3033 ar->ProbeCount = DefaultProbeCountForTypeUnique; 3034 ar->ProbeCount--; 3035 SetNextAnnounceProbeTime(m, ar); 3036 if (ar->ProbeCount == 0) 3037 { 3038 // If this is the last probe for this record, then see if we have any matching records 3039 // on our duplicate list which should similarly have their ProbeCount cleared to zero... 3040 AuthRecord *r2; 3041 for (r2 = m->DuplicateRecords; r2; r2=r2->next) 3042 if (r2->resrec.RecordType == kDNSRecordTypeUnique && RecordIsLocalDuplicate(r2, ar)) 3043 r2->ProbeCount = 0; 3044 // ... then acknowledge this record to the client. 3045 // We do this optimistically, just as we're about to send the third probe. 3046 // This helps clients that both advertise and browse, and want to filter themselves 3047 // from the browse results list, because it helps ensure that the registration 3048 // confirmation will be delivered 1/4 second *before* the browse "add" event. 3049 // A potential downside is that we could deliver a registration confirmation and then find out 3050 // moments later that there's a name conflict, but applications have to be prepared to handle 3051 // late conflicts anyway (e.g. on connection of network cable, etc.), so this is nothing new. 3052 if (!ar->Acknowledged) AcknowledgeRecord(m, ar); 3053 } 3054 } 3055 // else, if it has now finished probing, move it to state Verified, 3056 // and update m->NextScheduledResponse so it will be announced 3057 else 3058 { 3059 if (!ar->Acknowledged) AcknowledgeRecord(m, ar); // Defensive, just in case it got missed somehow 3060 ar->resrec.RecordType = kDNSRecordTypeVerified; 3061 ar->ThisAPInterval = DefaultAnnounceIntervalForTypeUnique; 3062 ar->LastAPTime = m->timenow - DefaultAnnounceIntervalForTypeUnique; 3063 SetNextAnnounceProbeTime(m, ar); 3064 } 3065 } 3066 } 3067 m->CurrentRecord = m->DuplicateRecords; 3068 while (m->CurrentRecord) 3069 { 3070 ar = m->CurrentRecord; 3071 m->CurrentRecord = ar->next; 3072 if (ar->resrec.RecordType == kDNSRecordTypeUnique && ar->ProbeCount == 0 && !ar->Acknowledged) 3073 AcknowledgeRecord(m, ar); 3074 } 3075 3076 // 3. Now we know which queries and probes we're sending, 3077 // go through our interface list sending the appropriate queries on each interface 3078 while (intf) 3079 { 3080 const int OwnerRecordSpace = (m->AnnounceOwner && intf->MAC.l[0]) ? DNSOpt_Header_Space + DNSOpt_Owner_Space(&m->PrimaryMAC, &intf->MAC) : 0; 3081 mDNSu8 *queryptr = m->omsg.data; 3082 InitializeDNSMessage(&m->omsg.h, zeroID, QueryFlags); 3083 if (KnownAnswerList) verbosedebugf("SendQueries: KnownAnswerList set... Will continue from previous packet"); 3084 if (!KnownAnswerList) 3085 { 3086 // Start a new known-answer list 3087 CacheRecord **kalistptr = &KnownAnswerList; 3088 mDNSu32 answerforecast = OwnerRecordSpace; // We start by assuming we'll need at least enough space to put the Owner Option 3089 3090 // Put query questions in this packet 3091 for (q = m->Questions; q && q != m->NewQuestions; q=q->next) 3092 { 3093 if (mDNSOpaque16IsZero(q->TargetQID) && (q->SendQNow == intf->InterfaceID)) 3094 { 3095 debugf("SendQueries: %s question for %##s (%s) at %d forecast total %d", 3096 SuppressOnThisInterface(q->DupSuppress, intf) ? "Suppressing" : "Putting ", 3097 q->qname.c, DNSTypeName(q->qtype), queryptr - m->omsg.data, queryptr + answerforecast - m->omsg.data); 3098 3099 // If we're suppressing this question, or we successfully put it, update its SendQNow state 3100 if (SuppressOnThisInterface(q->DupSuppress, intf) || 3101 BuildQuestion(m, &m->omsg, &queryptr, q, &kalistptr, &answerforecast)) 3102 { 3103 q->SendQNow = (q->InterfaceID || !q->SendOnAll) ? mDNSNULL : GetNextActiveInterfaceID(intf); 3104 if (q->WakeOnResolveCount) 3105 { 3106 mDNSSendWakeOnResolve(m, q); 3107 q->WakeOnResolveCount--; 3108 } 3109 } 3110 } 3111 } 3112 3113 // Put probe questions in this packet 3114 for (ar = m->ResourceRecords; ar; ar=ar->next) 3115 if (ar->SendRNow == intf->InterfaceID) 3116 { 3117 mDNSBool ucast = (ar->ProbeCount >= DefaultProbeCountForTypeUnique-1) && m->CanReceiveUnicastOn5353; 3118 mDNSu16 ucbit = (mDNSu16)(ucast ? kDNSQClass_UnicastResponse : 0); 3119 const mDNSu8 *const limit = m->omsg.data + (m->omsg.h.numQuestions ? NormalMaxDNSMessageData : AbsoluteMaxDNSMessageData); 3120 // We forecast: compressed name (2) type (2) class (2) TTL (4) rdlength (2) rdata (n) 3121 mDNSu32 forecast = answerforecast + 12 + ar->resrec.rdestimate; 3122 mDNSu8 *newptr = putQuestion(&m->omsg, queryptr, limit - forecast, ar->resrec.name, kDNSQType_ANY, (mDNSu16)(ar->resrec.rrclass | ucbit)); 3123 if (newptr) 3124 { 3125 queryptr = newptr; 3126 answerforecast = forecast; 3127 ar->SendRNow = (ar->resrec.InterfaceID) ? mDNSNULL : GetNextActiveInterfaceID(intf); 3128 ar->IncludeInProbe = mDNStrue; 3129 verbosedebugf("SendQueries: Put Question %##s (%s) probecount %d", 3130 ar->resrec.name->c, DNSTypeName(ar->resrec.rrtype), ar->ProbeCount); 3131 } 3132 } 3133 } 3134 3135 // Put our known answer list (either new one from this question or questions, or remainder of old one from last time) 3136 while (KnownAnswerList) 3137 { 3138 CacheRecord *ka = KnownAnswerList; 3139 mDNSu32 SecsSinceRcvd = ((mDNSu32)(m->timenow - ka->TimeRcvd)) / mDNSPlatformOneSecond; 3140 mDNSu8 *newptr = PutResourceRecordTTLWithLimit(&m->omsg, queryptr, &m->omsg.h.numAnswers, 3141 &ka->resrec, ka->resrec.rroriginalttl - SecsSinceRcvd, m->omsg.data + NormalMaxDNSMessageData - OwnerRecordSpace); 3142 if (newptr) 3143 { 3144 verbosedebugf("SendQueries: Put %##s (%s) at %d - %d", 3145 ka->resrec.name->c, DNSTypeName(ka->resrec.rrtype), queryptr - m->omsg.data, newptr - m->omsg.data); 3146 queryptr = newptr; 3147 KnownAnswerList = ka->NextInKAList; 3148 ka->NextInKAList = mDNSNULL; 3149 } 3150 else 3151 { 3152 // If we ran out of space and we have more than one question in the packet, that's an error -- 3153 // we shouldn't have put more than one question if there was a risk of us running out of space. 3154 if (m->omsg.h.numQuestions > 1) 3155 LogMsg("SendQueries: Put %d answers; No more space for known answers", m->omsg.h.numAnswers); 3156 m->omsg.h.flags.b[0] |= kDNSFlag0_TC; 3157 break; 3158 } 3159 } 3160 3161 for (ar = m->ResourceRecords; ar; ar=ar->next) 3162 if (ar->IncludeInProbe) 3163 { 3164 mDNSu8 *newptr = PutResourceRecord(&m->omsg, queryptr, &m->omsg.h.numAuthorities, &ar->resrec); 3165 ar->IncludeInProbe = mDNSfalse; 3166 if (newptr) queryptr = newptr; 3167 else LogMsg("SendQueries: How did we fail to have space for the Update record %s", ARDisplayString(m,ar)); 3168 } 3169 3170 if (queryptr > m->omsg.data) 3171 { 3172 if (OwnerRecordSpace) 3173 { 3174 AuthRecord opt; 3175 mDNS_SetupResourceRecord(&opt, mDNSNULL, mDNSInterface_Any, kDNSType_OPT, kStandardTTL, kDNSRecordTypeKnownUnique, AuthRecordAny, mDNSNULL, mDNSNULL); 3176 opt.resrec.rrclass = NormalMaxDNSMessageData; 3177 opt.resrec.rdlength = sizeof(rdataOPT); // One option in this OPT record 3178 opt.resrec.rdestimate = sizeof(rdataOPT); 3179 SetupOwnerOpt(m, intf, &opt.resrec.rdata->u.opt[0]); 3180 LogSPS("SendQueries putting %s", ARDisplayString(m, &opt)); 3181 queryptr = PutResourceRecordTTLWithLimit(&m->omsg, queryptr, &m->omsg.h.numAdditionals, 3182 &opt.resrec, opt.resrec.rroriginalttl, m->omsg.data + AbsoluteMaxDNSMessageData); 3183 if (!queryptr) 3184 LogMsg("SendQueries: How did we fail to have space for the OPT record (%d/%d/%d/%d) %s", 3185 m->omsg.h.numQuestions, m->omsg.h.numAnswers, m->omsg.h.numAuthorities, m->omsg.h.numAdditionals, ARDisplayString(m, &opt)); 3186 if (queryptr > m->omsg.data + NormalMaxDNSMessageData) 3187 if (m->omsg.h.numQuestions != 1 || m->omsg.h.numAnswers != 0 || m->omsg.h.numAuthorities != 1 || m->omsg.h.numAdditionals != 1) 3188 LogMsg("SendQueries: Why did we generate oversized packet with OPT record %p %p %p (%d/%d/%d/%d) %s", 3189 m->omsg.data, m->omsg.data + NormalMaxDNSMessageData, queryptr, 3190 m->omsg.h.numQuestions, m->omsg.h.numAnswers, m->omsg.h.numAuthorities, m->omsg.h.numAdditionals, ARDisplayString(m, &opt)); 3191 } 3192 3193 if ((m->omsg.h.flags.b[0] & kDNSFlag0_TC) && m->omsg.h.numQuestions > 1) 3194 LogMsg("SendQueries: Should not have more than one question (%d) in a truncated packet", m->omsg.h.numQuestions); 3195 debugf("SendQueries: Sending %d Question%s %d Answer%s %d Update%s on %p", 3196 m->omsg.h.numQuestions, m->omsg.h.numQuestions == 1 ? "" : "s", 3197 m->omsg.h.numAnswers, m->omsg.h.numAnswers == 1 ? "" : "s", 3198 m->omsg.h.numAuthorities, m->omsg.h.numAuthorities == 1 ? "" : "s", intf->InterfaceID); 3199 if (intf->IPv4Available) mDNSSendDNSMessage(m, &m->omsg, queryptr, intf->InterfaceID, mDNSNULL, &AllDNSLinkGroup_v4, MulticastDNSPort, mDNSNULL, mDNSNULL); 3200 if (intf->IPv6Available) mDNSSendDNSMessage(m, &m->omsg, queryptr, intf->InterfaceID, mDNSNULL, &AllDNSLinkGroup_v6, MulticastDNSPort, mDNSNULL, mDNSNULL); 3201 if (!m->SuppressSending) m->SuppressSending = NonZeroTime(m->timenow + (mDNSPlatformOneSecond+9)/10); 3202 if (++pktcount >= 1000) 3203 { LogMsg("SendQueries exceeded loop limit %d: giving up", pktcount); break; } 3204 // There might be more records left in the known answer list, or more questions to send 3205 // on this interface, so go around one more time and try again. 3206 } 3207 else // Nothing more to send on this interface; go to next 3208 { 3209 const NetworkInterfaceInfo *next = GetFirstActiveInterface(intf->next); 3210 #if MDNS_DEBUGMSGS && 0 3211 const char *const msg = next ? "SendQueries: Nothing more on %p; moving to %p" : "SendQueries: Nothing more on %p"; 3212 debugf(msg, intf, next); 3213 #endif 3214 intf = next; 3215 } 3216 } 3217 3218 // 4. Final housekeeping 3219 3220 // 4a. Debugging check: Make sure we announced all our records 3221 for (ar = m->ResourceRecords; ar; ar=ar->next) 3222 if (ar->SendRNow) 3223 { 3224 if (ar->ARType != AuthRecordLocalOnly && ar->ARType != AuthRecordP2P) 3225 LogMsg("SendQueries: No active interface %p to send probe: %p %s", ar->SendRNow, ar->resrec.InterfaceID, ARDisplayString(m, ar)); 3226 ar->SendRNow = mDNSNULL; 3227 } 3228 3229 // 4b. When we have lingering cache records that we're keeping around for a few seconds in the hope 3230 // that their interface which went away might come back again, the logic will want to send queries 3231 // for those records, but we can't because their interface isn't here any more, so to keep the 3232 // state machine ticking over we just pretend we did so. 3233 // If the interface does not come back in time, the cache record will expire naturally 3234 FORALL_CACHERECORDS(slot, cg, cr) 3235 if (cr->CRActiveQuestion && cr->UnansweredQueries < MaxUnansweredQueries) 3236 if (m->timenow + TicksTTL(cr)/50 - cr->NextRequiredQuery >= 0) 3237 { 3238 cr->UnansweredQueries++; 3239 cr->CRActiveQuestion->SendQNow = mDNSNULL; 3240 SetNextCacheCheckTimeForRecord(m, cr); 3241 } 3242 3243 // 4c. Debugging check: Make sure we sent all our planned questions 3244 // Do this AFTER the lingering cache records check above, because that will prevent spurious warnings for questions 3245 // we legitimately couldn't send because the interface is no longer available 3246 for (q = m->Questions; q; q=q->next) 3247 if (q->SendQNow) 3248 { 3249 DNSQuestion *x; 3250 for (x = m->NewQuestions; x; x=x->next) if (x == q) break; // Check if this question is a NewQuestion 3251 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)); 3252 q->SendQNow = mDNSNULL; 3253 } 3254 } 3255 3256 mDNSlocal void SendWakeup(mDNS *const m, mDNSInterfaceID InterfaceID, mDNSEthAddr *EthAddr, mDNSOpaque48 *password) 3257 { 3258 int i, j; 3259 mDNSu8 *ptr = m->omsg.data; 3260 NetworkInterfaceInfo *intf = FirstInterfaceForID(m, InterfaceID); 3261 if (!intf) { LogMsg("SendARP: No interface with InterfaceID %p found", InterfaceID); return; } 3262 3263 // 0x00 Destination address 3264 for (i=0; i<6; i++) *ptr++ = EthAddr->b[i]; 3265 3266 // 0x06 Source address (Note: Since we don't currently set the BIOCSHDRCMPLT option, BPF will fill in the real interface address for us) 3267 for (i=0; i<6; i++) *ptr++ = intf->MAC.b[0]; 3268 3269 // 0x0C Ethertype (0x0842) 3270 *ptr++ = 0x08; 3271 *ptr++ = 0x42; 3272 3273 // 0x0E Wakeup sync sequence 3274 for (i=0; i<6; i++) *ptr++ = 0xFF; 3275 3276 // 0x14 Wakeup data 3277 for (j=0; j<16; j++) for (i=0; i<6; i++) *ptr++ = EthAddr->b[i]; 3278 3279 // 0x74 Password 3280 for (i=0; i<6; i++) *ptr++ = password->b[i]; 3281 3282 mDNSPlatformSendRawPacket(m->omsg.data, ptr, InterfaceID); 3283 3284 // For Ethernet switches that don't flood-foward packets with unknown unicast destination MAC addresses, 3285 // broadcast is the only reliable way to get a wakeup packet to the intended target machine. 3286 // For 802.11 WPA networks, where a sleeping target machine may have missed a broadcast/multicast 3287 // key rotation, unicast is the only way to get a wakeup packet to the intended target machine. 3288 // So, we send one of each, unicast first, then broadcast second. 3289 for (i=0; i<6; i++) m->omsg.data[i] = 0xFF; 3290 mDNSPlatformSendRawPacket(m->omsg.data, ptr, InterfaceID); 3291 } 3292 3293 // *************************************************************************** 3294 #if COMPILER_LIKES_PRAGMA_MARK 3295 #pragma mark - 3296 #pragma mark - RR List Management & Task Management 3297 #endif 3298 3299 // Note: AnswerCurrentQuestionWithResourceRecord can call a user callback, which may change the record list and/or question list. 3300 // Any code walking either list must use the m->CurrentQuestion (and possibly m->CurrentRecord) mechanism to protect against this. 3301 // In fact, to enforce this, the routine will *only* answer the question currently pointed to by m->CurrentQuestion, 3302 // which will be auto-advanced (possibly to NULL) if the client callback cancels the question. 3303 mDNSexport void AnswerCurrentQuestionWithResourceRecord(mDNS *const m, CacheRecord *const rr, const QC_result AddRecord) 3304 { 3305 DNSQuestion *const q = m->CurrentQuestion; 3306 mDNSBool followcname = FollowCNAME(q, &rr->resrec, AddRecord); 3307 3308 verbosedebugf("AnswerCurrentQuestionWithResourceRecord:%4lu %s TTL %d %s", 3309 q->CurrentAnswers, AddRecord ? "Add" : "Rmv", rr->resrec.rroriginalttl, CRDisplayString(m, rr)); 3310 3311 // Normally we don't send out the unicast query if we have answered using our local only auth records e.g., /etc/hosts. 3312 // But if the query for "A" record has a local answer but query for "AAAA" record has no local answer, we might 3313 // send the AAAA query out which will come back with CNAME and will also answer the "A" query. To prevent that, 3314 // we check to see if that query already has a unique local answer. 3315 if (q->LOAddressAnswers) 3316 { 3317 LogInfo("AnswerCurrentQuestionWithResourceRecord: Question %p %##s (%s) not answering with record %s due to " 3318 "LOAddressAnswers %d", q, q->qname.c, DNSTypeName(q->qtype), ARDisplayString(m, rr), 3319 q->LOAddressAnswers); 3320 return; 3321 } 3322 3323 if (QuerySuppressed(q)) 3324 { 3325 // If the query is suppressed, then we don't want to answer from the cache. But if this query is 3326 // supposed to time out, we still want to callback the clients. We do this only for TimeoutQuestions 3327 // that are timing out, which we know are answered with Negative cache record when timing out. 3328 if (!q->TimeoutQuestion || rr->resrec.RecordType != kDNSRecordTypePacketNegative || (m->timenow - q->StopTime < 0)) 3329 return; 3330 } 3331 3332 // Note: Use caution here. In the case of records with rr->DelayDelivery set, AnswerCurrentQuestionWithResourceRecord(... mDNStrue) 3333 // may be called twice, once when the record is received, and again when it's time to notify local clients. 3334 // If any counters or similar are added here, care must be taken to ensure that they are not double-incremented by this. 3335 3336 rr->LastUsed = m->timenow; 3337 if (AddRecord == QC_add && !q->DuplicateOf && rr->CRActiveQuestion != q) 3338 { 3339 if (!rr->CRActiveQuestion) m->rrcache_active++; // If not previously active, increment rrcache_active count 3340 debugf("AnswerCurrentQuestionWithResourceRecord: Updating CRActiveQuestion from %p to %p for cache record %s, CurrentAnswer %d", 3341 rr->CRActiveQuestion, q, CRDisplayString(m,rr), q->CurrentAnswers); 3342 rr->CRActiveQuestion = q; // We know q is non-null 3343 SetNextCacheCheckTimeForRecord(m, rr); 3344 } 3345 3346 // If this is: 3347 // (a) a no-cache add, where we've already done at least one 'QM' query, or 3348 // (b) a normal add, where we have at least one unique-type answer, 3349 // then there's no need to keep polling the network. 3350 // (If we have an answer in the cache, then we'll automatically ask again in time to stop it expiring.) 3351 // We do this for mDNS questions and uDNS one-shot questions, but not for 3352 // uDNS LongLived questions, because that would mess up our LLQ lease renewal timing. 3353 if ((AddRecord == QC_addnocache && !q->RequestUnicast) || 3354 (AddRecord == QC_add && (q->ExpectUnique || (rr->resrec.RecordType & kDNSRecordTypePacketUniqueMask)))) 3355 if (ActiveQuestion(q) && (mDNSOpaque16IsZero(q->TargetQID) || !q->LongLived)) 3356 { 3357 q->LastQTime = m->timenow; 3358 q->LastQTxTime = m->timenow; 3359 q->RecentAnswerPkts = 0; 3360 q->ThisQInterval = MaxQuestionInterval; 3361 q->RequestUnicast = mDNSfalse; 3362 debugf("AnswerCurrentQuestionWithResourceRecord: Set MaxQuestionInterval for %##s (%s)", q->qname.c, DNSTypeName(q->qtype)); 3363 } 3364 3365 if (rr->DelayDelivery) return; // We'll come back later when CacheRecordDeferredAdd() calls us 3366 3367 // Only deliver negative answers if client has explicitly requested them 3368 if (rr->resrec.RecordType == kDNSRecordTypePacketNegative || (q->qtype != kDNSType_NSEC && RRAssertsNonexistence(&rr->resrec, q->qtype))) 3369 if (!AddRecord || !q->ReturnIntermed) return; 3370 3371 // For CNAME results to non-CNAME questions, only inform the client if they explicitly requested that 3372 if (q->QuestionCallback && !q->NoAnswer && (!followcname || q->ReturnIntermed)) 3373 { 3374 mDNS_DropLockBeforeCallback(); // Allow client (and us) to legally make mDNS API calls 3375 if (q->qtype != kDNSType_NSEC && RRAssertsNonexistence(&rr->resrec, q->qtype)) 3376 { 3377 CacheRecord neg; 3378 MakeNegativeCacheRecord(m, &neg, &q->qname, q->qnamehash, q->qtype, q->qclass, 1, rr->resrec.InterfaceID, q->qDNSServer); 3379 q->QuestionCallback(m, q, &neg.resrec, AddRecord); 3380 } 3381 else 3382 q->QuestionCallback(m, q, &rr->resrec, AddRecord); 3383 mDNS_ReclaimLockAfterCallback(); // Decrement mDNS_reentrancy to block mDNS API calls again 3384 } 3385 // Note: Proceed with caution here because client callback function is allowed to do anything, 3386 // including starting/stopping queries, registering/deregistering records, etc. 3387 3388 if (followcname && m->CurrentQuestion == q) 3389 AnswerQuestionByFollowingCNAME(m, q, &rr->resrec); 3390 } 3391 3392 // New Questions are answered through AnswerNewQuestion. But there may not have been any 3393 // matching cache records for the questions when it is called. There are two possibilities. 3394 // 3395 // 1) There are no cache records 3396 // 2) There are cache records but the DNSServers between question and cache record don't match. 3397 // 3398 // In the case of (1), where there are no cache records and later we add them when we get a response, 3399 // CacheRecordAdd/CacheRecordDeferredAdd will take care of adding the cache and delivering the ADD 3400 // events to the application. If we already have a cache entry, then no ADD events are delivered 3401 // unless the RDATA has changed 3402 // 3403 // In the case of (2) where we had the cache records and did not answer because of the DNSServer mismatch, 3404 // we need to answer them whenever we change the DNSServer. But we can't do it at the instant the DNSServer 3405 // changes because when we do the callback, the question can get deleted and the calling function would not 3406 // know how to handle it. So, we run this function from mDNS_Execute to handle DNSServer changes on the 3407 // question 3408 3409 mDNSlocal void AnswerQuestionsForDNSServerChanges(mDNS *const m) 3410 { 3411 DNSQuestion *q; 3412 DNSQuestion *qnext; 3413 CacheRecord *rr; 3414 mDNSu32 slot; 3415 CacheGroup *cg; 3416 3417 if (m->CurrentQuestion) 3418 LogMsg("AnswerQuestionsForDNSServerChanges: ERROR m->CurrentQuestion already set: %##s (%s)", 3419 m->CurrentQuestion->qname.c, DNSTypeName(m->CurrentQuestion->qtype)); 3420 3421 for (q = m->Questions; q && q != m->NewQuestions; q = qnext) 3422 { 3423 qnext = q->next; 3424 3425 // multicast or DNSServers did not change. 3426 if (mDNSOpaque16IsZero(q->TargetQID)) continue; 3427 if (!q->deliverAddEvents) continue; 3428 3429 // We are going to look through the cache for this question since it changed 3430 // its DNSserver last time. Reset it so that we don't call them again. Calling 3431 // them again will deliver duplicate events to the application 3432 q->deliverAddEvents = mDNSfalse; 3433 if (QuerySuppressed(q)) continue; 3434 m->CurrentQuestion = q; 3435 slot = HashSlot(&q->qname); 3436 cg = CacheGroupForName(m, slot, q->qnamehash, &q->qname); 3437 for (rr = cg ? cg->members : mDNSNULL; rr; rr=rr->next) 3438 { 3439 if (SameNameRecordAnswersQuestion(&rr->resrec, q)) 3440 { 3441 LogInfo("AnswerQuestionsForDNSServerChanges: Calling AnswerCurrentQuestionWithResourceRecord for question %p %##s using resource record %s", 3442 q, q->qname.c, CRDisplayString(m, rr)); 3443 // When this question penalizes a DNS server and has no more DNS servers to pick, we normally 3444 // deliver a negative cache response and suspend the question for 60 seconds (see uDNS_CheckCurrentQuestion). 3445 // But sometimes we may already find the negative cache entry and deliver that here as the process 3446 // of changing DNS servers. When the cache entry is about to expire, we will resend the question and 3447 // that time, we need to make sure that we have a valid DNS server. Otherwise, we will deliver 3448 // a negative cache response without trying the server. 3449 if (!q->qDNSServer && !q->DuplicateOf && rr->resrec.RecordType == kDNSRecordTypePacketNegative) 3450 { 3451 DNSQuestion *qptr; 3452 SetValidDNSServers(m, q); 3453 q->qDNSServer = GetServerForQuestion(m, q); 3454 for (qptr = q->next ; qptr; qptr = qptr->next) 3455 if (qptr->DuplicateOf == q) { qptr->validDNSServers = q->validDNSServers; qptr->qDNSServer = q->qDNSServer; } 3456 } 3457 q->CurrentAnswers++; 3458 if (rr->resrec.rdlength > SmallRecordLimit) q->LargeAnswers++; 3459 if (rr->resrec.RecordType & kDNSRecordTypePacketUniqueMask) q->UniqueAnswers++; 3460 AnswerCurrentQuestionWithResourceRecord(m, rr, QC_add); 3461 if (m->CurrentQuestion != q) break; // If callback deleted q, then we're finished here 3462 } 3463 } 3464 } 3465 m->CurrentQuestion = mDNSNULL; 3466 } 3467 3468 mDNSlocal void CacheRecordDeferredAdd(mDNS *const m, CacheRecord *rr) 3469 { 3470 rr->DelayDelivery = 0; 3471 if (m->CurrentQuestion) 3472 LogMsg("CacheRecordDeferredAdd ERROR m->CurrentQuestion already set: %##s (%s)", 3473 m->CurrentQuestion->qname.c, DNSTypeName(m->CurrentQuestion->qtype)); 3474 m->CurrentQuestion = m->Questions; 3475 while (m->CurrentQuestion && m->CurrentQuestion != m->NewQuestions) 3476 { 3477 DNSQuestion *q = m->CurrentQuestion; 3478 if (ResourceRecordAnswersQuestion(&rr->resrec, q)) 3479 AnswerCurrentQuestionWithResourceRecord(m, rr, QC_add); 3480 if (m->CurrentQuestion == q) // If m->CurrentQuestion was not auto-advanced, do it ourselves now 3481 m->CurrentQuestion = q->next; 3482 } 3483 m->CurrentQuestion = mDNSNULL; 3484 } 3485 3486 mDNSlocal mDNSs32 CheckForSoonToExpireRecords(mDNS *const m, const domainname *const name, const mDNSu32 namehash, const mDNSu32 slot) 3487 { 3488 const mDNSs32 threshhold = m->timenow + mDNSPlatformOneSecond; // See if there are any records expiring within one second 3489 const mDNSs32 start = m->timenow - 0x10000000; 3490 mDNSs32 delay = start; 3491 CacheGroup *cg = CacheGroupForName(m, slot, namehash, name); 3492 const CacheRecord *rr; 3493 for (rr = cg ? cg->members : mDNSNULL; rr; rr=rr->next) 3494 if (threshhold - RRExpireTime(rr) >= 0) // If we have records about to expire within a second 3495 if (delay - RRExpireTime(rr) < 0) // then delay until after they've been deleted 3496 delay = RRExpireTime(rr); 3497 if (delay - start > 0) return(NonZeroTime(delay)); 3498 else return(0); 3499 } 3500 3501 // CacheRecordAdd is only called from CreateNewCacheEntry, *never* directly as a result of a client API call. 3502 // If new questions are created as a result of invoking client callbacks, they will be added to 3503 // the end of the question list, and m->NewQuestions will be set to indicate the first new question. 3504 // rr is a new CacheRecord just received into our cache 3505 // (kDNSRecordTypePacketAns/PacketAnsUnique/PacketAdd/PacketAddUnique). 3506 // Note: CacheRecordAdd calls AnswerCurrentQuestionWithResourceRecord which can call a user callback, 3507 // which may change the record list and/or question list. 3508 // Any code walking either list must use the CurrentQuestion and/or CurrentRecord mechanism to protect against this. 3509 mDNSlocal void CacheRecordAdd(mDNS *const m, CacheRecord *rr) 3510 { 3511 DNSQuestion *q; 3512 3513 // We stop when we get to NewQuestions -- if we increment their CurrentAnswers/LargeAnswers/UniqueAnswers 3514 // counters here we'll end up double-incrementing them when we do it again in AnswerNewQuestion(). 3515 for (q = m->Questions; q && q != m->NewQuestions; q=q->next) 3516 { 3517 if (ResourceRecordAnswersQuestion(&rr->resrec, q)) 3518 { 3519 // If this question is one that's actively sending queries, and it's received ten answers within one 3520 // second of sending the last query packet, then that indicates some radical network topology change, 3521 // so reset its exponential backoff back to the start. We must be at least at the eight-second interval 3522 // to do this. If we're at the four-second interval, or less, there's not much benefit accelerating 3523 // because we will anyway send another query within a few seconds. The first reset query is sent out 3524 // randomized over the next four seconds to reduce possible synchronization between machines. 3525 if (q->LastAnswerPktNum != m->PktNum) 3526 { 3527 q->LastAnswerPktNum = m->PktNum; 3528 if (mDNSOpaque16IsZero(q->TargetQID) && ActiveQuestion(q) && ++q->RecentAnswerPkts >= 10 && 3529 q->ThisQInterval > InitialQuestionInterval * QuestionIntervalStep3 && m->timenow - q->LastQTxTime < mDNSPlatformOneSecond) 3530 { 3531 LogMsg("CacheRecordAdd: %##s (%s) got immediate answer burst (%d); restarting exponential backoff sequence (%d)", 3532 q->qname.c, DNSTypeName(q->qtype), q->RecentAnswerPkts, q->ThisQInterval); 3533 q->LastQTime = m->timenow - InitialQuestionInterval + (mDNSs32)mDNSRandom((mDNSu32)mDNSPlatformOneSecond*4); 3534 q->ThisQInterval = InitialQuestionInterval; 3535 SetNextQueryTime(m,q); 3536 } 3537 } 3538 verbosedebugf("CacheRecordAdd %p %##s (%s) %lu %#a:%d question %p", rr, rr->resrec.name->c, 3539 DNSTypeName(rr->resrec.rrtype), rr->resrec.rroriginalttl, rr->resrec.rDNSServer ? 3540 &rr->resrec.rDNSServer->addr : mDNSNULL, mDNSVal16(rr->resrec.rDNSServer ? 3541 rr->resrec.rDNSServer->port : zeroIPPort), q); 3542 q->CurrentAnswers++; 3543 q->unansweredQueries = 0; 3544 if (rr->resrec.rdlength > SmallRecordLimit) q->LargeAnswers++; 3545 if (rr->resrec.RecordType & kDNSRecordTypePacketUniqueMask) q->UniqueAnswers++; 3546 if (q->CurrentAnswers > 4000) 3547 { 3548 static int msgcount = 0; 3549 if (msgcount++ < 10) 3550 LogMsg("CacheRecordAdd: %##s (%s) has %d answers; shedding records to resist DOS attack", 3551 q->qname.c, DNSTypeName(q->qtype), q->CurrentAnswers); 3552 rr->resrec.rroriginalttl = 0; 3553 rr->UnansweredQueries = MaxUnansweredQueries; 3554 } 3555 } 3556 } 3557 3558 if (!rr->DelayDelivery) 3559 { 3560 if (m->CurrentQuestion) 3561 LogMsg("CacheRecordAdd ERROR m->CurrentQuestion already set: %##s (%s)", m->CurrentQuestion->qname.c, DNSTypeName(m->CurrentQuestion->qtype)); 3562 m->CurrentQuestion = m->Questions; 3563 while (m->CurrentQuestion && m->CurrentQuestion != m->NewQuestions) 3564 { 3565 q = m->CurrentQuestion; 3566 if (ResourceRecordAnswersQuestion(&rr->resrec, q)) 3567 AnswerCurrentQuestionWithResourceRecord(m, rr, QC_add); 3568 if (m->CurrentQuestion == q) // If m->CurrentQuestion was not auto-advanced, do it ourselves now 3569 m->CurrentQuestion = q->next; 3570 } 3571 m->CurrentQuestion = mDNSNULL; 3572 } 3573 3574 SetNextCacheCheckTimeForRecord(m, rr); 3575 } 3576 3577 // NoCacheAnswer is only called from mDNSCoreReceiveResponse, *never* directly as a result of a client API call. 3578 // If new questions are created as a result of invoking client callbacks, they will be added to 3579 // the end of the question list, and m->NewQuestions will be set to indicate the first new question. 3580 // rr is a new CacheRecord just received from the wire (kDNSRecordTypePacketAns/AnsUnique/Add/AddUnique) 3581 // but we don't have any place to cache it. We'll deliver question 'add' events now, but we won't have any 3582 // way to deliver 'remove' events in future, nor will we be able to include this in known-answer lists, 3583 // so we immediately bump ThisQInterval up to MaxQuestionInterval to avoid pounding the network. 3584 // Note: NoCacheAnswer calls AnswerCurrentQuestionWithResourceRecord which can call a user callback, 3585 // which may change the record list and/or question list. 3586 // Any code walking either list must use the CurrentQuestion and/or CurrentRecord mechanism to protect against this. 3587 mDNSlocal void NoCacheAnswer(mDNS *const m, CacheRecord *rr) 3588 { 3589 LogMsg("No cache space: Delivering non-cached result for %##s", m->rec.r.resrec.name->c); 3590 if (m->CurrentQuestion) 3591 LogMsg("NoCacheAnswer ERROR m->CurrentQuestion already set: %##s (%s)", m->CurrentQuestion->qname.c, DNSTypeName(m->CurrentQuestion->qtype)); 3592 m->CurrentQuestion = m->Questions; 3593 // We do this for *all* questions, not stopping when we get to m->NewQuestions, 3594 // since we're not caching the record and we'll get no opportunity to do this later 3595 while (m->CurrentQuestion) 3596 { 3597 DNSQuestion *q = m->CurrentQuestion; 3598 if (ResourceRecordAnswersQuestion(&rr->resrec, q)) 3599 AnswerCurrentQuestionWithResourceRecord(m, rr, QC_addnocache); // QC_addnocache means "don't expect remove events for this" 3600 if (m->CurrentQuestion == q) // If m->CurrentQuestion was not auto-advanced, do it ourselves now 3601 m->CurrentQuestion = q->next; 3602 } 3603 m->CurrentQuestion = mDNSNULL; 3604 } 3605 3606 // CacheRecordRmv is only called from CheckCacheExpiration, which is called from mDNS_Execute. 3607 // Note that CacheRecordRmv is *only* called for records that are referenced by at least one active question. 3608 // If new questions are created as a result of invoking client callbacks, they will be added to 3609 // the end of the question list, and m->NewQuestions will be set to indicate the first new question. 3610 // rr is an existing cache CacheRecord that just expired and is being deleted 3611 // (kDNSRecordTypePacketAns/PacketAnsUnique/PacketAdd/PacketAddUnique). 3612 // Note: CacheRecordRmv calls AnswerCurrentQuestionWithResourceRecord which can call a user callback, 3613 // which may change the record list and/or question list. 3614 // Any code walking either list must use the CurrentQuestion and/or CurrentRecord mechanism to protect against this. 3615 mDNSlocal void CacheRecordRmv(mDNS *const m, CacheRecord *rr) 3616 { 3617 if (m->CurrentQuestion) 3618 LogMsg("CacheRecordRmv ERROR m->CurrentQuestion already set: %##s (%s)", 3619 m->CurrentQuestion->qname.c, DNSTypeName(m->CurrentQuestion->qtype)); 3620 m->CurrentQuestion = m->Questions; 3621 3622 // We stop when we get to NewQuestions -- for new questions their CurrentAnswers/LargeAnswers/UniqueAnswers counters 3623 // will all still be zero because we haven't yet gone through the cache counting how many answers we have for them. 3624 while (m->CurrentQuestion && m->CurrentQuestion != m->NewQuestions) 3625 { 3626 DNSQuestion *q = m->CurrentQuestion; 3627 // When a question enters suppressed state, we generate RMV events and generate a negative 3628 // response. A cache may be present that answers this question e.g., cache entry generated 3629 // before the question became suppressed. We need to skip the suppressed questions here as 3630 // the RMV event has already been generated. 3631 if (!QuerySuppressed(q) && ResourceRecordAnswersQuestion(&rr->resrec, q)) 3632 { 3633 verbosedebugf("CacheRecordRmv %p %s", rr, CRDisplayString(m, rr)); 3634 q->FlappingInterface1 = mDNSNULL; 3635 q->FlappingInterface2 = mDNSNULL; 3636 3637 // When a question changes DNS server, it is marked with deliverAddEvents if we find any 3638 // cache entry corresponding to the new DNS server. Before we deliver the ADD event, the 3639 // cache entry may be removed in which case CurrentAnswers can be zero. 3640 if (q->deliverAddEvents && !q->CurrentAnswers) 3641 { 3642 LogInfo("CacheRecordRmv: Question %p %##s (%s) deliverAddEvents set, DNSServer %#a:%d", 3643 q, q->qname.c, DNSTypeName(q->qtype), q->qDNSServer ? &q->qDNSServer->addr : mDNSNULL, 3644 mDNSVal16(q->qDNSServer ? q->qDNSServer->port : zeroIPPort)); 3645 m->CurrentQuestion = q->next; 3646 continue; 3647 } 3648 if (q->CurrentAnswers == 0) 3649 LogMsg("CacheRecordRmv ERROR!!: How can CurrentAnswers already be zero for %p %##s (%s) DNSServer %#a:%d", 3650 q, q->qname.c, DNSTypeName(q->qtype), q->qDNSServer ? &q->qDNSServer->addr : mDNSNULL, 3651 mDNSVal16(q->qDNSServer ? q->qDNSServer->port : zeroIPPort)); 3652 else 3653 { 3654 q->CurrentAnswers--; 3655 if (rr->resrec.rdlength > SmallRecordLimit) q->LargeAnswers--; 3656 if (rr->resrec.RecordType & kDNSRecordTypePacketUniqueMask) q->UniqueAnswers--; 3657 } 3658 if (rr->resrec.rdata->MaxRDLength) // Never generate "remove" events for negative results 3659 { 3660 if (q->CurrentAnswers == 0) 3661 { 3662 LogInfo("CacheRecordRmv: Last answer for %##s (%s) expired from cache; will reconfirm antecedents", 3663 q->qname.c, DNSTypeName(q->qtype)); 3664 ReconfirmAntecedents(m, &q->qname, q->qnamehash, 0); 3665 } 3666 AnswerCurrentQuestionWithResourceRecord(m, rr, QC_rmv); 3667 } 3668 } 3669 if (m->CurrentQuestion == q) // If m->CurrentQuestion was not auto-advanced, do it ourselves now 3670 m->CurrentQuestion = q->next; 3671 } 3672 m->CurrentQuestion = mDNSNULL; 3673 } 3674 3675 mDNSlocal void ReleaseCacheEntity(mDNS *const m, CacheEntity *e) 3676 { 3677 #if APPLE_OSX_mDNSResponder && MACOSX_MDNS_MALLOC_DEBUGGING >= 1 3678 unsigned int i; 3679 for (i=0; i<sizeof(*e); i++) ((char*)e)[i] = 0xFF; 3680 #endif 3681 e->next = m->rrcache_free; 3682 m->rrcache_free = e; 3683 m->rrcache_totalused--; 3684 } 3685 3686 mDNSlocal void ReleaseCacheGroup(mDNS *const m, CacheGroup **cp) 3687 { 3688 CacheEntity *e = (CacheEntity *)(*cp); 3689 //LogMsg("ReleaseCacheGroup: Releasing CacheGroup for %p, %##s", (*cp)->name->c, (*cp)->name->c); 3690 if ((*cp)->rrcache_tail != &(*cp)->members) 3691 LogMsg("ERROR: (*cp)->members == mDNSNULL but (*cp)->rrcache_tail != &(*cp)->members)"); 3692 //if ((*cp)->name != (domainname*)((*cp)->namestorage)) 3693 // LogMsg("ReleaseCacheGroup: %##s, %p %p", (*cp)->name->c, (*cp)->name, (domainname*)((*cp)->namestorage)); 3694 if ((*cp)->name != (domainname*)((*cp)->namestorage)) mDNSPlatformMemFree((*cp)->name); 3695 (*cp)->name = mDNSNULL; 3696 *cp = (*cp)->next; // Cut record from list 3697 ReleaseCacheEntity(m, e); 3698 } 3699 3700 mDNSlocal void ReleaseCacheRecord(mDNS *const m, CacheRecord *r) 3701 { 3702 //LogMsg("ReleaseCacheRecord: Releasing %s", CRDisplayString(m, r)); 3703 if (r->resrec.rdata && r->resrec.rdata != (RData*)&r->smallrdatastorage) mDNSPlatformMemFree(r->resrec.rdata); 3704 r->resrec.rdata = mDNSNULL; 3705 ReleaseCacheEntity(m, (CacheEntity *)r); 3706 } 3707 3708 // Note: We want to be careful that we deliver all the CacheRecordRmv calls before delivering 3709 // CacheRecordDeferredAdd calls. The in-order nature of the cache lists ensures that all 3710 // callbacks for old records are delivered before callbacks for newer records. 3711 mDNSlocal void CheckCacheExpiration(mDNS *const m, const mDNSu32 slot, CacheGroup *const cg) 3712 { 3713 CacheRecord **rp = &cg->members; 3714 3715 if (m->lock_rrcache) { LogMsg("CheckCacheExpiration ERROR! Cache already locked!"); return; } 3716 m->lock_rrcache = 1; 3717 3718 while (*rp) 3719 { 3720 CacheRecord *const rr = *rp; 3721 mDNSs32 event = RRExpireTime(rr); 3722 if (m->timenow - event >= 0) // If expired, delete it 3723 { 3724 *rp = rr->next; // Cut it from the list 3725 verbosedebugf("CheckCacheExpiration: Deleting%7d %7d %p %s", 3726 m->timenow - rr->TimeRcvd, rr->resrec.rroriginalttl, rr->CRActiveQuestion, CRDisplayString(m, rr)); 3727 if (rr->CRActiveQuestion) // If this record has one or more active questions, tell them it's going away 3728 { 3729 DNSQuestion *q = rr->CRActiveQuestion; 3730 // When a cache record is about to expire, we expect to do four queries at 80-82%, 85-87%, 90-92% and 3731 // then 95-97% of the TTL. If the DNS server does not respond, then we will remove the cache entry 3732 // before we pick a new DNS server. As the question interval is set to MaxQuestionInterval, we may 3733 // not send out a query anytime soon. Hence, we need to reset the question interval. If this is 3734 // a normal deferred ADD case, then AnswerCurrentQuestionWithResourceRecord will reset it to 3735 // MaxQuestionInterval. If we have inactive questions referring to negative cache entries, 3736 // don't ressurect them as they will deliver duplicate "No such Record" ADD events 3737 if (!mDNSOpaque16IsZero(q->TargetQID) && !q->LongLived && ActiveQuestion(q)) 3738 { 3739 q->ThisQInterval = InitialQuestionInterval; 3740 q->LastQTime = m->timenow - q->ThisQInterval; 3741 SetNextQueryTime(m, q); 3742 } 3743 CacheRecordRmv(m, rr); 3744 m->rrcache_active--; 3745 } 3746 ReleaseCacheRecord(m, rr); 3747 } 3748 else // else, not expired; see if we need to query 3749 { 3750 // If waiting to delay delivery, do nothing until then 3751 if (rr->DelayDelivery && rr->DelayDelivery - m->timenow > 0) 3752 event = rr->DelayDelivery; 3753 else 3754 { 3755 if (rr->DelayDelivery) CacheRecordDeferredAdd(m, rr); 3756 if (rr->CRActiveQuestion && rr->UnansweredQueries < MaxUnansweredQueries) 3757 { 3758 if (m->timenow - rr->NextRequiredQuery < 0) // If not yet time for next query 3759 event = NextCacheCheckEvent(rr); // then just record when we want the next query 3760 else // else trigger our question to go out now 3761 { 3762 // Set NextScheduledQuery to timenow so that SendQueries() will run. 3763 // SendQueries() will see that we have records close to expiration, and send FEQs for them. 3764 m->NextScheduledQuery = m->timenow; 3765 // After sending the query we'll increment UnansweredQueries and call SetNextCacheCheckTimeForRecord(), 3766 // which will correctly update m->NextCacheCheck for us. 3767 event = m->timenow + 0x3FFFFFFF; 3768 } 3769 } 3770 } 3771 verbosedebugf("CheckCacheExpiration:%6d %5d %s", 3772 (event - m->timenow) / mDNSPlatformOneSecond, CacheCheckGracePeriod(rr), CRDisplayString(m, rr)); 3773 if (m->rrcache_nextcheck[slot] - event > 0) 3774 m->rrcache_nextcheck[slot] = event; 3775 rp = &rr->next; 3776 } 3777 } 3778 if (cg->rrcache_tail != rp) verbosedebugf("CheckCacheExpiration: Updating CacheGroup tail from %p to %p", cg->rrcache_tail, rp); 3779 cg->rrcache_tail = rp; 3780 m->lock_rrcache = 0; 3781 } 3782 3783 mDNSlocal void AnswerNewQuestion(mDNS *const m) 3784 { 3785 mDNSBool ShouldQueryImmediately = mDNStrue; 3786 DNSQuestion *const q = m->NewQuestions; // Grab the question we're going to answer 3787 mDNSu32 slot = HashSlot(&q->qname); 3788 CacheGroup *const cg = CacheGroupForName(m, slot, q->qnamehash, &q->qname); 3789 AuthRecord *lr; 3790 AuthGroup *ag; 3791 mDNSBool AnsweredFromCache = mDNSfalse; 3792 3793 verbosedebugf("AnswerNewQuestion: Answering %##s (%s)", q->qname.c, DNSTypeName(q->qtype)); 3794 3795 if (cg) CheckCacheExpiration(m, slot, cg); 3796 if (m->NewQuestions != q) { LogInfo("AnswerNewQuestion: Question deleted while doing CheckCacheExpiration"); goto exit; } 3797 m->NewQuestions = q->next; 3798 // Advance NewQuestions to the next *after* calling CheckCacheExpiration, because if we advance it first 3799 // then CheckCacheExpiration may give this question add/remove callbacks, and it's not yet ready for that. 3800 // 3801 // Also, CheckCacheExpiration() calls CacheRecordDeferredAdd() and CacheRecordRmv(), which invoke 3802 // client callbacks, which may delete their own or any other question. Our mechanism for detecting 3803 // whether our current m->NewQuestions question got deleted by one of these callbacks is to store the 3804 // value of m->NewQuestions in 'q' before calling CheckCacheExpiration(), and then verify afterwards 3805 // that they're still the same. If m->NewQuestions has changed (because mDNS_StopQuery_internal 3806 // advanced it), that means the question was deleted, so we no longer need to worry about answering 3807 // it (and indeed 'q' is now a dangling pointer, so dereferencing it at all would be bad, and the 3808 // values we computed for slot and cg are now stale and relate to a question that no longer exists). 3809 // 3810 // We can't use the usual m->CurrentQuestion mechanism for this because CacheRecordDeferredAdd() and 3811 // CacheRecordRmv() both use that themselves when walking the list of (non-new) questions generating callbacks. 3812 // Fortunately mDNS_StopQuery_internal auto-advances both m->CurrentQuestion *AND* m->NewQuestions when 3813 // deleting a question, so luckily we have an easy alternative way of detecting if our question got deleted. 3814 3815 if (m->lock_rrcache) LogMsg("AnswerNewQuestion ERROR! Cache already locked!"); 3816 // This should be safe, because calling the client's question callback may cause the 3817 // question list to be modified, but should not ever cause the rrcache list to be modified. 3818 // If the client's question callback deletes the question, then m->CurrentQuestion will 3819 // be advanced, and we'll exit out of the loop 3820 m->lock_rrcache = 1; 3821 if (m->CurrentQuestion) 3822 LogMsg("AnswerNewQuestion ERROR m->CurrentQuestion already set: %##s (%s)", 3823 m->CurrentQuestion->qname.c, DNSTypeName(m->CurrentQuestion->qtype)); 3824 m->CurrentQuestion = q; // Indicate which question we're answering, so we'll know if it gets deleted 3825 3826 if (q->NoAnswer == NoAnswer_Fail) 3827 { 3828 LogMsg("AnswerNewQuestion: NoAnswer_Fail %##s (%s)", q->qname.c, DNSTypeName(q->qtype)); 3829 MakeNegativeCacheRecord(m, &m->rec.r, &q->qname, q->qnamehash, q->qtype, q->qclass, 60, mDNSInterface_Any, q->qDNSServer); 3830 q->NoAnswer = NoAnswer_Normal; // Temporarily turn off answer suppression 3831 AnswerCurrentQuestionWithResourceRecord(m, &m->rec.r, QC_addnocache); 3832 // Don't touch the question if it has been stopped already 3833 if (m->CurrentQuestion == q) q->NoAnswer = NoAnswer_Fail; // Restore NoAnswer state 3834 m->rec.r.resrec.RecordType = 0; // Clear RecordType to show we're not still using it 3835 } 3836 if (m->CurrentQuestion != q) { LogInfo("AnswerNewQuestion: Question deleted while generating NoAnswer_Fail response"); goto exit; } 3837 3838 // See if we want to tell it about LocalOnly records 3839 if (m->CurrentRecord) 3840 LogMsg("AnswerNewQuestion ERROR m->CurrentRecord already set %s", ARDisplayString(m, m->CurrentRecord)); 3841 slot = AuthHashSlot(&q->qname); 3842 ag = AuthGroupForName(&m->rrauth, slot, q->qnamehash, &q->qname); 3843 if (ag) 3844 { 3845 m->CurrentRecord = ag->members; 3846 while (m->CurrentRecord && m->CurrentRecord != ag->NewLocalOnlyRecords) 3847 { 3848 AuthRecord *rr = m->CurrentRecord; 3849 m->CurrentRecord = rr->next; 3850 // 3851 // If the question is mDNSInterface_LocalOnly, all records local to the machine should be used 3852 // to answer the query. This is handled in AnswerNewLocalOnlyQuestion. 3853 // 3854 // We handle mDNSInterface_Any and scoped questions here. See LocalOnlyRecordAnswersQuestion for more 3855 // details on how we handle this case. For P2P we just handle "Interface_Any" questions. For LocalOnly 3856 // we handle both mDNSInterface_Any and scoped questions. 3857 3858 if (rr->ARType == AuthRecordLocalOnly || (rr->ARType == AuthRecordP2P && q->InterfaceID == mDNSInterface_Any)) 3859 if (LocalOnlyRecordAnswersQuestion(rr, q)) 3860 { 3861 AnswerLocalQuestionWithLocalAuthRecord(m, rr, mDNStrue); 3862 if (m->CurrentQuestion != q) break; // If callback deleted q, then we're finished here 3863 } 3864 } 3865 } 3866 m->CurrentRecord = mDNSNULL; 3867 3868 if (m->CurrentQuestion != q) { LogInfo("AnswerNewQuestion: Question deleted while while giving LocalOnly record answers"); goto exit; } 3869 3870 if (q->LOAddressAnswers) 3871 { 3872 LogInfo("AnswerNewQuestion: Question %p %##s (%s) answered using local auth records LOAddressAnswers %d", 3873 q, q->qname.c, DNSTypeName(q->qtype), q->LOAddressAnswers); 3874 goto exit; 3875 } 3876 3877 // Before we go check the cache and ship this query on the wire, we have to be sure that there are 3878 // no local records that could possibly answer this question. As we did not check the NewLocalRecords, we 3879 // need to just peek at them to see whether it will answer this question. If it would answer, pretend 3880 // that we answered. AnswerAllLocalQuestionsWithLocalAuthRecord will answer shortly. This happens normally 3881 // when we add new /etc/hosts entries and restart the question. It is a new question and also a new record. 3882 if (ag) 3883 { 3884 lr = ag->NewLocalOnlyRecords; 3885 while (lr) 3886 { 3887 if (LORecordAnswersAddressType(lr) && LocalOnlyRecordAnswersQuestion(lr, q)) 3888 { 3889 LogInfo("AnswerNewQuestion: Question %p %##s (%s) will be answered using new local auth records " 3890 " LOAddressAnswers %d", q, q->qname.c, DNSTypeName(q->qtype), q->LOAddressAnswers); 3891 goto exit; 3892 } 3893 lr = lr->next; 3894 } 3895 } 3896 3897 3898 // If we are not supposed to answer this question, generate a negative response. 3899 // Temporarily suspend the SuppressQuery so that AnswerCurrentQuestionWithResourceRecord can answer the question 3900 if (QuerySuppressed(q)) { q->SuppressQuery = mDNSfalse; GenerateNegativeResponse(m); q->SuppressQuery = mDNStrue; } 3901 else 3902 { 3903 CacheRecord *rr; 3904 for (rr = cg ? cg->members : mDNSNULL; rr; rr=rr->next) 3905 if (SameNameRecordAnswersQuestion(&rr->resrec, q)) 3906 { 3907 // SecsSinceRcvd is whole number of elapsed seconds, rounded down 3908 mDNSu32 SecsSinceRcvd = ((mDNSu32)(m->timenow - rr->TimeRcvd)) / mDNSPlatformOneSecond; 3909 if (rr->resrec.rroriginalttl <= SecsSinceRcvd) 3910 { 3911 LogMsg("AnswerNewQuestion: How is rr->resrec.rroriginalttl %lu <= SecsSinceRcvd %lu for %s %d %d", 3912 rr->resrec.rroriginalttl, SecsSinceRcvd, CRDisplayString(m, rr), m->timenow, rr->TimeRcvd); 3913 continue; // Go to next one in loop 3914 } 3915 3916 // If this record set is marked unique, then that means we can reasonably assume we have the whole set 3917 // -- we don't need to rush out on the network and query immediately to see if there are more answers out there 3918 if ((rr->resrec.RecordType & kDNSRecordTypePacketUniqueMask) || (q->ExpectUnique)) 3919 ShouldQueryImmediately = mDNSfalse; 3920 q->CurrentAnswers++; 3921 if (rr->resrec.rdlength > SmallRecordLimit) q->LargeAnswers++; 3922 if (rr->resrec.RecordType & kDNSRecordTypePacketUniqueMask) q->UniqueAnswers++; 3923 AnsweredFromCache = mDNStrue; 3924 AnswerCurrentQuestionWithResourceRecord(m, rr, QC_add); 3925 if (m->CurrentQuestion != q) break; // If callback deleted q, then we're finished here 3926 } 3927 else if (RRTypeIsAddressType(rr->resrec.rrtype) && RRTypeIsAddressType(q->qtype)) 3928 ShouldQueryImmediately = mDNSfalse; 3929 } 3930 // We don't use LogInfo for this "Question deleted" message because it happens so routinely that 3931 // it's not remotely remarkable, and therefore unlikely to be of much help tracking down bugs. 3932 if (m->CurrentQuestion != q) { debugf("AnswerNewQuestion: Question deleted while giving cache answers"); goto exit; } 3933 3934 // Neither a local record nor a cache entry could answer this question. If this question need to be retried 3935 // with search domains, generate a negative response which will now retry after appending search domains. 3936 // If the query was suppressed above, we already generated a negative response. When it gets unsuppressed, 3937 // we will retry with search domains. 3938 if (!QuerySuppressed(q) && !AnsweredFromCache && q->RetryWithSearchDomains) 3939 { 3940 LogInfo("AnswerNewQuestion: Generating response for retrying with search domains %##s (%s)", q->qname.c, DNSTypeName(q->qtype)); 3941 GenerateNegativeResponse(m); 3942 } 3943 3944 if (m->CurrentQuestion != q) { debugf("AnswerNewQuestion: Question deleted while giving negative answer"); goto exit; } 3945 3946 // Note: When a query gets suppressed or retried with search domains, we de-activate the question. 3947 // Hence we don't execute the following block of code for those cases. 3948 if (ShouldQueryImmediately && ActiveQuestion(q)) 3949 { 3950 debugf("AnswerNewQuestion: ShouldQueryImmediately %##s (%s)", q->qname.c, DNSTypeName(q->qtype)); 3951 q->ThisQInterval = InitialQuestionInterval; 3952 q->LastQTime = m->timenow - q->ThisQInterval; 3953 if (mDNSOpaque16IsZero(q->TargetQID)) // For mDNS, spread packets to avoid a burst of simultaneous queries 3954 { 3955 // Compute random delay in the range 1-6 seconds, then divide by 50 to get 20-120ms 3956 if (!m->RandomQueryDelay) 3957 m->RandomQueryDelay = (mDNSPlatformOneSecond + mDNSRandom(mDNSPlatformOneSecond*5) - 1) / 50 + 1; 3958 q->LastQTime += m->RandomQueryDelay; 3959 } 3960 } 3961 3962 // IN ALL CASES make sure that m->NextScheduledQuery is set appropriately. 3963 // In cases where m->NewQuestions->DelayAnswering is set, we may have delayed generating our 3964 // answers for this question until *after* its scheduled transmission time, in which case 3965 // m->NextScheduledQuery may now be set to 'never', and in that case -- even though we're *not* doing 3966 // ShouldQueryImmediately -- we still need to make sure we set m->NextScheduledQuery correctly. 3967 SetNextQueryTime(m,q); 3968 3969 exit: 3970 m->CurrentQuestion = mDNSNULL; 3971 m->lock_rrcache = 0; 3972 } 3973 3974 // When a NewLocalOnlyQuestion is created, AnswerNewLocalOnlyQuestion runs though our ResourceRecords delivering any 3975 // appropriate answers, stopping if it reaches a NewLocalOnlyRecord -- these will be handled by AnswerAllLocalQuestionsWithLocalAuthRecord 3976 mDNSlocal void AnswerNewLocalOnlyQuestion(mDNS *const m) 3977 { 3978 mDNSu32 slot; 3979 AuthGroup *ag; 3980 DNSQuestion *q = m->NewLocalOnlyQuestions; // Grab the question we're going to answer 3981 m->NewLocalOnlyQuestions = q->next; // Advance NewLocalOnlyQuestions to the next (if any) 3982 3983 debugf("AnswerNewLocalOnlyQuestion: Answering %##s (%s)", q->qname.c, DNSTypeName(q->qtype)); 3984 3985 if (m->CurrentQuestion) 3986 LogMsg("AnswerNewLocalOnlyQuestion ERROR m->CurrentQuestion already set: %##s (%s)", 3987 m->CurrentQuestion->qname.c, DNSTypeName(m->CurrentQuestion->qtype)); 3988 m->CurrentQuestion = q; // Indicate which question we're answering, so we'll know if it gets deleted 3989 3990 if (m->CurrentRecord) 3991 LogMsg("AnswerNewLocalOnlyQuestion ERROR m->CurrentRecord already set %s", ARDisplayString(m, m->CurrentRecord)); 3992 3993 // 1. First walk the LocalOnly records answering the LocalOnly question 3994 // 2. As LocalOnly questions should also be answered by any other Auth records local to the machine, 3995 // walk the ResourceRecords list delivering the answers 3996 slot = AuthHashSlot(&q->qname); 3997 ag = AuthGroupForName(&m->rrauth, slot, q->qnamehash, &q->qname); 3998 if (ag) 3999 { 4000 m->CurrentRecord = ag->members; 4001 while (m->CurrentRecord && m->CurrentRecord != ag->NewLocalOnlyRecords) 4002 { 4003 AuthRecord *rr = m->CurrentRecord; 4004 m->CurrentRecord = rr->next; 4005 if (LocalOnlyRecordAnswersQuestion(rr, q)) 4006 { 4007 AnswerLocalQuestionWithLocalAuthRecord(m, rr, mDNStrue); 4008 if (m->CurrentQuestion != q) break; // If callback deleted q, then we're finished here 4009 } 4010 } 4011 } 4012 4013 if (m->CurrentQuestion == q) 4014 { 4015 m->CurrentRecord = m->ResourceRecords; 4016 4017 while (m->CurrentRecord && m->CurrentRecord != m->NewLocalRecords) 4018 { 4019 AuthRecord *rr = m->CurrentRecord; 4020 m->CurrentRecord = rr->next; 4021 if (ResourceRecordAnswersQuestion(&rr->resrec, q)) 4022 { 4023 AnswerLocalQuestionWithLocalAuthRecord(m, rr, mDNStrue); 4024 if (m->CurrentQuestion != q) break; // If callback deleted q, then we're finished here 4025 } 4026 } 4027 } 4028 4029 m->CurrentQuestion = mDNSNULL; 4030 m->CurrentRecord = mDNSNULL; 4031 } 4032 4033 mDNSlocal CacheEntity *GetCacheEntity(mDNS *const m, const CacheGroup *const PreserveCG) 4034 { 4035 CacheEntity *e = mDNSNULL; 4036 4037 if (m->lock_rrcache) { LogMsg("GetFreeCacheRR ERROR! Cache already locked!"); return(mDNSNULL); } 4038 m->lock_rrcache = 1; 4039 4040 // If we have no free records, ask the client layer to give us some more memory 4041 if (!m->rrcache_free && m->MainCallback) 4042 { 4043 if (m->rrcache_totalused != m->rrcache_size) 4044 LogMsg("GetFreeCacheRR: count mismatch: m->rrcache_totalused %lu != m->rrcache_size %lu", 4045 m->rrcache_totalused, m->rrcache_size); 4046 4047 // We don't want to be vulnerable to a malicious attacker flooding us with an infinite 4048 // number of bogus records so that we keep growing our cache until the machine runs out of memory. 4049 // To guard against this, if our cache grows above 512kB (approx 3168 records at 164 bytes each), 4050 // and we're actively using less than 1/32 of that cache, then we purge all the unused records 4051 // and recycle them, instead of allocating more memory. 4052 if (m->rrcache_size > 5000 && m->rrcache_size / 32 > m->rrcache_active) 4053 LogInfo("Possible denial-of-service attack in progress: m->rrcache_size %lu; m->rrcache_active %lu", 4054 m->rrcache_size, m->rrcache_active); 4055 else 4056 { 4057 mDNS_DropLockBeforeCallback(); // Allow client to legally make mDNS API calls from the callback 4058 m->MainCallback(m, mStatus_GrowCache); 4059 mDNS_ReclaimLockAfterCallback(); // Decrement mDNS_reentrancy to block mDNS API calls again 4060 } 4061 } 4062 4063 // If we still have no free records, recycle all the records we can. 4064 // Enumerating the entire cache is moderately expensive, so when we do it, we reclaim all the records we can in one pass. 4065 if (!m->rrcache_free) 4066 { 4067 mDNSu32 oldtotalused = m->rrcache_totalused; 4068 mDNSu32 slot; 4069 for (slot = 0; slot < CACHE_HASH_SLOTS; slot++) 4070 { 4071 CacheGroup **cp = &m->rrcache_hash[slot]; 4072 while (*cp) 4073 { 4074 CacheRecord **rp = &(*cp)->members; 4075 while (*rp) 4076 { 4077 // Records that answer still-active questions are not candidates for recycling 4078 // Records that are currently linked into the CacheFlushRecords list may not be recycled, or we'll crash 4079 if ((*rp)->CRActiveQuestion || (*rp)->NextInCFList) 4080 rp=&(*rp)->next; 4081 else 4082 { 4083 CacheRecord *rr = *rp; 4084 *rp = (*rp)->next; // Cut record from list 4085 ReleaseCacheRecord(m, rr); 4086 } 4087 } 4088 if ((*cp)->rrcache_tail != rp) 4089 verbosedebugf("GetFreeCacheRR: Updating rrcache_tail[%lu] from %p to %p", slot, (*cp)->rrcache_tail, rp); 4090 (*cp)->rrcache_tail = rp; 4091 if ((*cp)->members || (*cp)==PreserveCG) cp=&(*cp)->next; 4092 else ReleaseCacheGroup(m, cp); 4093 } 4094 } 4095 LogInfo("GetCacheEntity recycled %d records to reduce cache from %d to %d", 4096 oldtotalused - m->rrcache_totalused, oldtotalused, m->rrcache_totalused); 4097 } 4098 4099 if (m->rrcache_free) // If there are records in the free list, take one 4100 { 4101 e = m->rrcache_free; 4102 m->rrcache_free = e->next; 4103 if (++m->rrcache_totalused >= m->rrcache_report) 4104 { 4105 LogInfo("RR Cache now using %ld objects", m->rrcache_totalused); 4106 if (m->rrcache_report < 100) m->rrcache_report += 10; 4107 else if (m->rrcache_report < 1000) m->rrcache_report += 100; 4108 else m->rrcache_report += 1000; 4109 } 4110 mDNSPlatformMemZero(e, sizeof(*e)); 4111 } 4112 4113 m->lock_rrcache = 0; 4114 4115 return(e); 4116 } 4117 4118 mDNSlocal CacheRecord *GetCacheRecord(mDNS *const m, CacheGroup *cg, mDNSu16 RDLength) 4119 { 4120 CacheRecord *r = (CacheRecord *)GetCacheEntity(m, cg); 4121 if (r) 4122 { 4123 r->resrec.rdata = (RData*)&r->smallrdatastorage; // By default, assume we're usually going to be using local storage 4124 if (RDLength > InlineCacheRDSize) // If RDLength is too big, allocate extra storage 4125 { 4126 r->resrec.rdata = (RData*)mDNSPlatformMemAllocate(sizeofRDataHeader + RDLength); 4127 if (r->resrec.rdata) r->resrec.rdata->MaxRDLength = r->resrec.rdlength = RDLength; 4128 else { ReleaseCacheEntity(m, (CacheEntity*)r); r = mDNSNULL; } 4129 } 4130 } 4131 return(r); 4132 } 4133 4134 mDNSlocal CacheGroup *GetCacheGroup(mDNS *const m, const mDNSu32 slot, const ResourceRecord *const rr) 4135 { 4136 mDNSu16 namelen = DomainNameLength(rr->name); 4137 CacheGroup *cg = (CacheGroup*)GetCacheEntity(m, mDNSNULL); 4138 if (!cg) { LogMsg("GetCacheGroup: Failed to allocate memory for %##s", rr->name->c); return(mDNSNULL); } 4139 cg->next = m->rrcache_hash[slot]; 4140 cg->namehash = rr->namehash; 4141 cg->members = mDNSNULL; 4142 cg->rrcache_tail = &cg->members; 4143 cg->name = (domainname*)cg->namestorage; 4144 //LogMsg("GetCacheGroup: %-10s %d-byte cache name %##s", 4145 // (namelen > InlineCacheGroupNameSize) ? "Allocating" : "Inline", namelen, rr->name->c); 4146 if (namelen > InlineCacheGroupNameSize) cg->name = mDNSPlatformMemAllocate(namelen); 4147 if (!cg->name) 4148 { 4149 LogMsg("GetCacheGroup: Failed to allocate name storage for %##s", rr->name->c); 4150 ReleaseCacheEntity(m, (CacheEntity*)cg); 4151 return(mDNSNULL); 4152 } 4153 AssignDomainName(cg->name, rr->name); 4154 4155 if (CacheGroupForRecord(m, slot, rr)) LogMsg("GetCacheGroup: Already have CacheGroup for %##s", rr->name->c); 4156 m->rrcache_hash[slot] = cg; 4157 if (CacheGroupForRecord(m, slot, rr) != cg) LogMsg("GetCacheGroup: Not finding CacheGroup for %##s", rr->name->c); 4158 4159 return(cg); 4160 } 4161 4162 mDNSexport void mDNS_PurgeCacheResourceRecord(mDNS *const m, CacheRecord *rr) 4163 { 4164 if (m->mDNS_busy != m->mDNS_reentrancy+1) 4165 LogMsg("mDNS_PurgeCacheResourceRecord: Lock not held! mDNS_busy (%ld) mDNS_reentrancy (%ld)", m->mDNS_busy, m->mDNS_reentrancy); 4166 // Make sure we mark this record as thoroughly expired -- we don't ever want to give 4167 // a positive answer using an expired record (e.g. from an interface that has gone away). 4168 // We don't want to clear CRActiveQuestion here, because that would leave the record subject to 4169 // summary deletion without giving the proper callback to any questions that are monitoring it. 4170 // By setting UnansweredQueries to MaxUnansweredQueries we ensure it won't trigger any further expiration queries. 4171 rr->TimeRcvd = m->timenow - mDNSPlatformOneSecond * 60; 4172 rr->UnansweredQueries = MaxUnansweredQueries; 4173 rr->resrec.rroriginalttl = 0; 4174 SetNextCacheCheckTimeForRecord(m, rr); 4175 } 4176 4177 mDNSexport mDNSs32 mDNS_TimeNow(const mDNS *const m) 4178 { 4179 mDNSs32 time; 4180 mDNSPlatformLock(m); 4181 if (m->mDNS_busy) 4182 { 4183 LogMsg("mDNS_TimeNow called while holding mDNS lock. This is incorrect. Code protected by lock should just use m->timenow."); 4184 if (!m->timenow) LogMsg("mDNS_TimeNow: m->mDNS_busy is %ld but m->timenow not set", m->mDNS_busy); 4185 } 4186 4187 if (m->timenow) time = m->timenow; 4188 else time = mDNS_TimeNow_NoLock(m); 4189 mDNSPlatformUnlock(m); 4190 return(time); 4191 } 4192 4193 // To avoid pointless CPU thrash, we use SetSPSProxyListChanged(X) to record the last interface that 4194 // had its Sleep Proxy client list change, and defer to actual BPF reconfiguration to mDNS_Execute(). 4195 // (GetNextScheduledEvent() returns "now" when m->SPSProxyListChanged is set) 4196 #define SetSPSProxyListChanged(X) do { \ 4197 if (m->SPSProxyListChanged && m->SPSProxyListChanged != (X)) mDNSPlatformUpdateProxyList(m, m->SPSProxyListChanged); \ 4198 m->SPSProxyListChanged = (X); } while(0) 4199 4200 // Called from mDNS_Execute() to expire stale proxy records 4201 mDNSlocal void CheckProxyRecords(mDNS *const m, AuthRecord *list) 4202 { 4203 m->CurrentRecord = list; 4204 while (m->CurrentRecord) 4205 { 4206 AuthRecord *rr = m->CurrentRecord; 4207 if (rr->resrec.RecordType != kDNSRecordTypeDeregistering && rr->WakeUp.HMAC.l[0]) 4208 { 4209 // If m->SPSSocket is NULL that means we're not acting as a sleep proxy any more, 4210 // so we need to cease proxying for *all* records we may have, expired or not. 4211 if (m->SPSSocket && m->timenow - rr->TimeExpire < 0) // If proxy record not expired yet, update m->NextScheduledSPS 4212 { 4213 if (m->NextScheduledSPS - rr->TimeExpire > 0) 4214 m->NextScheduledSPS = rr->TimeExpire; 4215 } 4216 else // else proxy record expired, so remove it 4217 { 4218 LogSPS("CheckProxyRecords: Removing %d H-MAC %.6a I-MAC %.6a %d %s", 4219 m->ProxyRecords, &rr->WakeUp.HMAC, &rr->WakeUp.IMAC, rr->WakeUp.seq, ARDisplayString(m, rr)); 4220 SetSPSProxyListChanged(rr->resrec.InterfaceID); 4221 mDNS_Deregister_internal(m, rr, mDNS_Dereg_normal); 4222 // Don't touch rr after this -- memory may have been free'd 4223 } 4224 } 4225 // Mustn't advance m->CurrentRecord until *after* mDNS_Deregister_internal, because 4226 // new records could have been added to the end of the list as a result of that call. 4227 if (m->CurrentRecord == rr) // If m->CurrentRecord was not advanced for us, do it now 4228 m->CurrentRecord = rr->next; 4229 } 4230 } 4231 4232 mDNSlocal void CheckRmvEventsForLocalRecords(mDNS *const m) 4233 { 4234 while (m->CurrentRecord) 4235 { 4236 AuthRecord *rr = m->CurrentRecord; 4237 if (rr->AnsweredLocalQ && rr->resrec.RecordType == kDNSRecordTypeDeregistering) 4238 { 4239 debugf("CheckRmvEventsForLocalRecords: Generating local RMV events for %s", ARDisplayString(m, rr)); 4240 rr->resrec.RecordType = kDNSRecordTypeShared; 4241 AnswerAllLocalQuestionsWithLocalAuthRecord(m, rr, mDNSfalse); 4242 if (m->CurrentRecord == rr) // If rr still exists in list, restore its state now 4243 { 4244 rr->resrec.RecordType = kDNSRecordTypeDeregistering; 4245 rr->AnsweredLocalQ = mDNSfalse; 4246 // SendResponses normally calls CompleteDeregistration after sending goodbyes. 4247 // For LocalOnly records, we don't do that and hence we need to do that here. 4248 if (RRLocalOnly(rr)) CompleteDeregistration(m, rr); 4249 } 4250 } 4251 if (m->CurrentRecord == rr) // If m->CurrentRecord was not auto-advanced, do it ourselves now 4252 m->CurrentRecord = rr->next; 4253 } 4254 } 4255 4256 mDNSlocal void TimeoutQuestions(mDNS *const m) 4257 { 4258 m->NextScheduledStopTime = m->timenow + 0x3FFFFFFF; 4259 if (m->CurrentQuestion) 4260 LogMsg("TimeoutQuestions ERROR m->CurrentQuestion already set: %##s (%s)", m->CurrentQuestion->qname.c, 4261 DNSTypeName(m->CurrentQuestion->qtype)); 4262 m->CurrentQuestion = m->Questions; 4263 while (m->CurrentQuestion) 4264 { 4265 DNSQuestion *const q = m->CurrentQuestion; 4266 if (q->StopTime) 4267 { 4268 if (m->timenow - q->StopTime >= 0) 4269 { 4270 LogInfo("TimeoutQuestions: question %##s timed out, time %d", q->qname.c, m->timenow - q->StopTime); 4271 GenerateNegativeResponse(m); 4272 if (m->CurrentQuestion == q) q->StopTime = 0; 4273 } 4274 else 4275 { 4276 if (m->NextScheduledStopTime - q->StopTime > 0) 4277 m->NextScheduledStopTime = q->StopTime; 4278 } 4279 } 4280 // If m->CurrentQuestion wasn't modified out from under us, advance it now 4281 // We can't do this at the start of the loop because GenerateNegativeResponse 4282 // depends on having m->CurrentQuestion point to the right question 4283 if (m->CurrentQuestion == q) 4284 m->CurrentQuestion = q->next; 4285 } 4286 m->CurrentQuestion = mDNSNULL; 4287 } 4288 4289 mDNSexport mDNSs32 mDNS_Execute(mDNS *const m) 4290 { 4291 mDNS_Lock(m); // Must grab lock before trying to read m->timenow 4292 4293 if (m->timenow - m->NextScheduledEvent >= 0) 4294 { 4295 int i; 4296 AuthRecord *head, *tail; 4297 mDNSu32 slot; 4298 AuthGroup *ag; 4299 4300 verbosedebugf("mDNS_Execute"); 4301 4302 if (m->CurrentQuestion) 4303 LogMsg("mDNS_Execute: ERROR m->CurrentQuestion already set: %##s (%s)", 4304 m->CurrentQuestion->qname.c, DNSTypeName(m->CurrentQuestion->qtype)); 4305 4306 if (m->CurrentRecord) 4307 LogMsg("mDNS_Execute: ERROR m->CurrentRecord already set: %s", ARDisplayString(m, m->CurrentRecord)); 4308 4309 // 1. If we're past the probe suppression time, we can clear it 4310 if (m->SuppressProbes && m->timenow - m->SuppressProbes >= 0) m->SuppressProbes = 0; 4311 4312 // 2. If it's been more than ten seconds since the last probe failure, we can clear the counter 4313 if (m->NumFailedProbes && m->timenow - m->ProbeFailTime >= mDNSPlatformOneSecond * 10) m->NumFailedProbes = 0; 4314 4315 // 3. Purge our cache of stale old records 4316 if (m->rrcache_size && m->timenow - m->NextCacheCheck >= 0) 4317 { 4318 mDNSu32 numchecked = 0; 4319 m->NextCacheCheck = m->timenow + 0x3FFFFFFF; 4320 for (slot = 0; slot < CACHE_HASH_SLOTS; slot++) 4321 { 4322 if (m->timenow - m->rrcache_nextcheck[slot] >= 0) 4323 { 4324 CacheGroup **cp = &m->rrcache_hash[slot]; 4325 m->rrcache_nextcheck[slot] = m->timenow + 0x3FFFFFFF; 4326 while (*cp) 4327 { 4328 debugf("m->NextCacheCheck %4d Slot %3d %##s", numchecked, slot, *cp ? (*cp)->name : (domainname*)"\x04NULL"); 4329 numchecked++; 4330 CheckCacheExpiration(m, slot, *cp); 4331 if ((*cp)->members) cp=&(*cp)->next; 4332 else ReleaseCacheGroup(m, cp); 4333 } 4334 } 4335 // Even if we didn't need to actually check this slot yet, still need to 4336 // factor its nextcheck time into our overall NextCacheCheck value 4337 if (m->NextCacheCheck - m->rrcache_nextcheck[slot] > 0) 4338 m->NextCacheCheck = m->rrcache_nextcheck[slot]; 4339 } 4340 debugf("m->NextCacheCheck %4d checked, next in %d", numchecked, m->NextCacheCheck - m->timenow); 4341 } 4342 4343 if (m->timenow - m->NextScheduledSPS >= 0) 4344 { 4345 m->NextScheduledSPS = m->timenow + 0x3FFFFFFF; 4346 CheckProxyRecords(m, m->DuplicateRecords); // Clear m->DuplicateRecords first, then m->ResourceRecords 4347 CheckProxyRecords(m, m->ResourceRecords); 4348 } 4349 4350 SetSPSProxyListChanged(mDNSNULL); // Perform any deferred BPF reconfiguration now 4351 4352 // Clear AnnounceOwner if necessary. (Do this *before* SendQueries() and SendResponses().) 4353 if (m->AnnounceOwner && m->timenow - m->AnnounceOwner >= 0) m->AnnounceOwner = 0; 4354 4355 if (m->DelaySleep && m->timenow - m->DelaySleep >= 0) 4356 { 4357 m->DelaySleep = 0; 4358 if (m->SleepState == SleepState_Transferring) 4359 { 4360 LogSPS("Re-sleep delay passed; now checking for Sleep Proxy Servers"); 4361 BeginSleepProcessing(m); 4362 } 4363 } 4364 4365 // 4. See if we can answer any of our new local questions from the cache 4366 for (i=0; m->NewQuestions && i<1000; i++) 4367 { 4368 if (m->NewQuestions->DelayAnswering && m->timenow - m->NewQuestions->DelayAnswering < 0) break; 4369 AnswerNewQuestion(m); 4370 } 4371 if (i >= 1000) LogMsg("mDNS_Execute: AnswerNewQuestion exceeded loop limit"); 4372 4373 // Make sure we deliver *all* local RMV events, and clear the corresponding rr->AnsweredLocalQ flags, *before* 4374 // we begin generating *any* new ADD events in the m->NewLocalOnlyQuestions and m->NewLocalRecords loops below. 4375 for (i=0; i<1000 && m->LocalRemoveEvents; i++) 4376 { 4377 m->LocalRemoveEvents = mDNSfalse; 4378 m->CurrentRecord = m->ResourceRecords; 4379 CheckRmvEventsForLocalRecords(m); 4380 // Walk the LocalOnly records and deliver the RMV events 4381 for (slot = 0; slot < AUTH_HASH_SLOTS; slot++) 4382 for (ag = m->rrauth.rrauth_hash[slot]; ag; ag = ag->next) 4383 { 4384 m->CurrentRecord = ag->members; 4385 if (m->CurrentRecord) CheckRmvEventsForLocalRecords(m); 4386 } 4387 } 4388 4389 if (i >= 1000) LogMsg("mDNS_Execute: m->LocalRemoveEvents exceeded loop limit"); 4390 4391 for (i=0; m->NewLocalOnlyQuestions && i<1000; i++) AnswerNewLocalOnlyQuestion(m); 4392 if (i >= 1000) LogMsg("mDNS_Execute: AnswerNewLocalOnlyQuestion exceeded loop limit"); 4393 4394 head = tail = mDNSNULL; 4395 for (i=0; i<1000 && m->NewLocalRecords && m->NewLocalRecords != head; i++) 4396 { 4397 AuthRecord *rr = m->NewLocalRecords; 4398 m->NewLocalRecords = m->NewLocalRecords->next; 4399 if (LocalRecordReady(rr)) 4400 { 4401 debugf("mDNS_Execute: Delivering Add event with LocalAuthRecord %s", ARDisplayString(m, rr)); 4402 AnswerAllLocalQuestionsWithLocalAuthRecord(m, rr, mDNStrue); 4403 } 4404 else if (!rr->next) 4405 { 4406 // If we have just one record that is not ready, we don't have to unlink and 4407 // reinsert. As the NewLocalRecords will be NULL for this case, the loop will 4408 // terminate and set the NewLocalRecords to rr. 4409 debugf("mDNS_Execute: Just one LocalAuthRecord %s, breaking out of the loop early", ARDisplayString(m, rr)); 4410 if (head != mDNSNULL || m->NewLocalRecords != mDNSNULL) 4411 LogMsg("mDNS_Execute: ERROR!!: head %p, NewLocalRecords %p", head, m->NewLocalRecords); 4412 4413 head = rr; 4414 } 4415 else 4416 { 4417 AuthRecord **p = &m->ResourceRecords; // Find this record in our list of active records 4418 debugf("mDNS_Execute: Skipping LocalAuthRecord %s", ARDisplayString(m, rr)); 4419 // if this is the first record we are skipping, move to the end of the list. 4420 // if we have already skipped records before, append it at the end. 4421 while (*p && *p != rr) p=&(*p)->next; 4422 if (*p) *p = rr->next; // Cut this record from the list 4423 else { LogMsg("mDNS_Execute: ERROR!! Cannot find record %s in ResourceRecords list", ARDisplayString(m, rr)); break; } 4424 if (!head) 4425 { 4426 while (*p) p=&(*p)->next; 4427 *p = rr; 4428 head = tail = rr; 4429 } 4430 else 4431 { 4432 tail->next = rr; 4433 tail = rr; 4434 } 4435 rr->next = mDNSNULL; 4436 } 4437 } 4438 m->NewLocalRecords = head; 4439 debugf("mDNS_Execute: Setting NewLocalRecords to %s", (head ? ARDisplayString(m, head) : "NULL")); 4440 4441 if (i >= 1000) LogMsg("mDNS_Execute: m->NewLocalRecords exceeded loop limit"); 4442 4443 // Check to see if we have any new LocalOnly/P2P records to examine for delivering 4444 // to our local questions 4445 if (m->NewLocalOnlyRecords) 4446 { 4447 m->NewLocalOnlyRecords = mDNSfalse; 4448 for (slot = 0; slot < AUTH_HASH_SLOTS; slot++) 4449 for (ag = m->rrauth.rrauth_hash[slot]; ag; ag = ag->next) 4450 { 4451 for (i=0; i<100 && ag->NewLocalOnlyRecords; i++) 4452 { 4453 AuthRecord *rr = ag->NewLocalOnlyRecords; 4454 ag->NewLocalOnlyRecords = ag->NewLocalOnlyRecords->next; 4455 // LocalOnly records should always be ready as they never probe 4456 if (LocalRecordReady(rr)) 4457 { 4458 debugf("mDNS_Execute: Delivering Add event with LocalAuthRecord %s", ARDisplayString(m, rr)); 4459 AnswerAllLocalQuestionsWithLocalAuthRecord(m, rr, mDNStrue); 4460 } 4461 else LogMsg("mDNS_Execute: LocalOnlyRecord %s not ready", ARDisplayString(m, rr)); 4462 } 4463 // We limit about 100 per AuthGroup that can be serviced at a time 4464 if (i >= 100) LogMsg("mDNS_Execute: ag->NewLocalOnlyRecords exceeded loop limit"); 4465 } 4466 } 4467 4468 // 5. Some questions may have picked a new DNS server and the cache may answer these questions now. 4469 AnswerQuestionsForDNSServerChanges(m); 4470 4471 // 6. See what packets we need to send 4472 if (m->mDNSPlatformStatus != mStatus_NoError || (m->SleepState == SleepState_Sleeping)) 4473 DiscardDeregistrations(m); 4474 if (m->mDNSPlatformStatus == mStatus_NoError && (m->SuppressSending == 0 || m->timenow - m->SuppressSending >= 0)) 4475 { 4476 // If the platform code is ready, and we're not suppressing packet generation right now 4477 // then send our responses, probes, and questions. 4478 // We check the cache first, because there might be records close to expiring that trigger questions to refresh them. 4479 // We send queries next, because there might be final-stage probes that complete their probing here, causing 4480 // them to advance to announcing state, and we want those to be included in any announcements we send out. 4481 // Finally, we send responses, including the previously mentioned records that just completed probing. 4482 m->SuppressSending = 0; 4483 4484 // 7. Send Query packets. This may cause some probing records to advance to announcing state 4485 if (m->timenow - m->NextScheduledQuery >= 0 || m->timenow - m->NextScheduledProbe >= 0) SendQueries(m); 4486 if (m->timenow - m->NextScheduledQuery >= 0) 4487 { 4488 DNSQuestion *q; 4489 LogMsg("mDNS_Execute: SendQueries didn't send all its queries (%d - %d = %d) will try again in one second", 4490 m->timenow, m->NextScheduledQuery, m->timenow - m->NextScheduledQuery); 4491 m->NextScheduledQuery = m->timenow + mDNSPlatformOneSecond; 4492 for (q = m->Questions; q && q != m->NewQuestions; q=q->next) 4493 if (ActiveQuestion(q) && m->timenow - NextQSendTime(q) >= 0) 4494 LogMsg("mDNS_Execute: SendQueries didn't send %##s (%s)", q->qname.c, DNSTypeName(q->qtype)); 4495 } 4496 if (m->timenow - m->NextScheduledProbe >= 0) 4497 { 4498 LogMsg("mDNS_Execute: SendQueries didn't send all its probes (%d - %d = %d) will try again in one second", 4499 m->timenow, m->NextScheduledProbe, m->timenow - m->NextScheduledProbe); 4500 m->NextScheduledProbe = m->timenow + mDNSPlatformOneSecond; 4501 } 4502 4503 // 8. Send Response packets, including probing records just advanced to announcing state 4504 if (m->timenow - m->NextScheduledResponse >= 0) SendResponses(m); 4505 if (m->timenow - m->NextScheduledResponse >= 0) 4506 { 4507 LogMsg("mDNS_Execute: SendResponses didn't send all its responses; will try again in one second"); 4508 m->NextScheduledResponse = m->timenow + mDNSPlatformOneSecond; 4509 } 4510 } 4511 4512 // Clear RandomDelay values, ready to pick a new different value next time 4513 m->RandomQueryDelay = 0; 4514 m->RandomReconfirmDelay = 0; 4515 4516 if (m->NextScheduledStopTime && m->timenow - m->NextScheduledStopTime >= 0) TimeoutQuestions(m); 4517 #ifndef UNICAST_DISABLED 4518 if (m->NextSRVUpdate && m->timenow - m->NextSRVUpdate >= 0) UpdateAllSRVRecords(m); 4519 if (m->timenow - m->NextScheduledNATOp >= 0) CheckNATMappings(m); 4520 if (m->timenow - m->NextuDNSEvent >= 0) uDNS_Tasks(m); 4521 #endif 4522 } 4523 4524 // Note about multi-threaded systems: 4525 // On a multi-threaded system, some other thread could run right after the mDNS_Unlock(), 4526 // performing mDNS API operations that change our next scheduled event time. 4527 // 4528 // On multi-threaded systems (like the current Windows implementation) that have a single main thread 4529 // calling mDNS_Execute() (and other threads allowed to call mDNS API routines) it is the responsibility 4530 // of the mDNSPlatformUnlock() routine to signal some kind of stateful condition variable that will 4531 // signal whatever blocking primitive the main thread is using, so that it will wake up and execute one 4532 // more iteration of its loop, and immediately call mDNS_Execute() again. The signal has to be stateful 4533 // in the sense that if the main thread has not yet entered its blocking primitive, then as soon as it 4534 // does, the state of the signal will be noticed, causing the blocking primitive to return immediately 4535 // without blocking. This avoids the race condition between the signal from the other thread arriving 4536 // just *before* or just *after* the main thread enters the blocking primitive. 4537 // 4538 // On multi-threaded systems (like the current Mac OS 9 implementation) that are entirely timer-driven, 4539 // with no main mDNS_Execute() thread, it is the responsibility of the mDNSPlatformUnlock() routine to 4540 // set the timer according to the m->NextScheduledEvent value, and then when the timer fires, the timer 4541 // callback function should call mDNS_Execute() (and ignore the return value, which may already be stale 4542 // by the time it gets to the timer callback function). 4543 4544 mDNS_Unlock(m); // Calling mDNS_Unlock is what gives m->NextScheduledEvent its new value 4545 return(m->NextScheduledEvent); 4546 } 4547 4548 mDNSlocal void SuspendLLQs(mDNS *m) 4549 { 4550 DNSQuestion *q; 4551 for (q = m->Questions; q; q = q->next) 4552 if (ActiveQuestion(q) && !mDNSOpaque16IsZero(q->TargetQID) && q->LongLived && q->state == LLQ_Established) 4553 { q->ReqLease = 0; sendLLQRefresh(m, q); } 4554 } 4555 4556 mDNSlocal mDNSBool QuestionHasLocalAnswers(mDNS *const m, DNSQuestion *q) 4557 { 4558 AuthRecord *rr; 4559 mDNSu32 slot; 4560 AuthGroup *ag; 4561 4562 slot = AuthHashSlot(&q->qname); 4563 ag = AuthGroupForName(&m->rrauth, slot, q->qnamehash, &q->qname); 4564 if (ag) 4565 { 4566 for (rr = ag->members; rr; rr=rr->next) 4567 // Filter the /etc/hosts records - LocalOnly, Unique, A/AAAA/CNAME 4568 if (LORecordAnswersAddressType(rr) && LocalOnlyRecordAnswersQuestion(rr, q)) 4569 { 4570 LogInfo("QuestionHasLocalAnswers: Question %p %##s (%s) has local answer %s", q, q->qname.c, DNSTypeName(q->qtype), ARDisplayString(m, rr)); 4571 return mDNStrue; 4572 } 4573 } 4574 return mDNSfalse; 4575 } 4576 4577 // ActivateUnicastQuery() is called from three places: 4578 // 1. When a new question is created 4579 // 2. On wake from sleep 4580 // 3. When the DNS configuration changes 4581 // In case 1 we don't want to mess with our established ThisQInterval and LastQTime (ScheduleImmediately is false) 4582 // In cases 2 and 3 we do want to cause the question to be resent immediately (ScheduleImmediately is true) 4583 mDNSlocal void ActivateUnicastQuery(mDNS *const m, DNSQuestion *const question, mDNSBool ScheduleImmediately) 4584 { 4585 // For now this AutoTunnel stuff is specific to Mac OS X. 4586 // In the future, if there's demand, we may see if we can abstract it out cleanly into the platform layer 4587 #if APPLE_OSX_mDNSResponder 4588 // Even though BTMM client tunnels are only useful for AAAA queries, we need to treat v4 and v6 queries equally. 4589 // Otherwise we can get the situation where the A query completes really fast (with an NXDOMAIN result) and the 4590 // caller then gives up waiting for the AAAA result while we're still in the process of setting up the tunnel. 4591 // To level the playing field, we block both A and AAAA queries while tunnel setup is in progress, and then 4592 // returns results for both at the same time. If we are looking for the _autotunnel6 record, then skip this logic 4593 // as this would trigger looking up _autotunnel6._autotunnel6 and end up failing the original query. 4594 4595 if (RRTypeIsAddressType(question->qtype) && PrivateQuery(question) && 4596 !SameDomainLabel(question->qname.c, (const mDNSu8 *)"\x0c_autotunnel6")&& question->QuestionCallback != AutoTunnelCallback) 4597 { 4598 question->NoAnswer = NoAnswer_Suspended; 4599 AddNewClientTunnel(m, question); 4600 return; 4601 } 4602 #endif // APPLE_OSX_mDNSResponder 4603 4604 if (!question->DuplicateOf) 4605 { 4606 debugf("ActivateUnicastQuery: %##s %s%s%s", 4607 question->qname.c, DNSTypeName(question->qtype), PrivateQuery(question) ? " (Private)" : "", ScheduleImmediately ? " ScheduleImmediately" : ""); 4608 question->CNAMEReferrals = 0; 4609 if (question->nta) { CancelGetZoneData(m, question->nta); question->nta = mDNSNULL; } 4610 if (question->LongLived) 4611 { 4612 question->state = LLQ_InitialRequest; 4613 question->id = zeroOpaque64; 4614 question->servPort = zeroIPPort; 4615 if (question->tcp) { DisposeTCPConn(question->tcp); question->tcp = mDNSNULL; } 4616 } 4617 // If the question has local answers, then we don't want answers from outside 4618 if (ScheduleImmediately && !QuestionHasLocalAnswers(m, question)) 4619 { 4620 question->ThisQInterval = InitialQuestionInterval; 4621 question->LastQTime = m->timenow - question->ThisQInterval; 4622 SetNextQueryTime(m, question); 4623 } 4624 } 4625 } 4626 4627 // Caller should hold the lock 4628 mDNSexport void mDNSCoreRestartAddressQueries(mDNS *const m, mDNSBool SearchDomainsChanged, FlushCache flushCacheRecords, 4629 CallbackBeforeStartQuery BeforeStartCallback, void *context) 4630 { 4631 DNSQuestion *q; 4632 DNSQuestion *restart = mDNSNULL; 4633 4634 if (!m->mDNS_busy) LogMsg("mDNSCoreRestartAddressQueries: ERROR!! Lock not held"); 4635 4636 // 1. Flush the cache records 4637 if (flushCacheRecords) flushCacheRecords(m); 4638 4639 // 2. Even though we may have purged the cache records above, before it can generate RMV event 4640 // we are going to stop the question. Hence we need to deliver the RMV event before we 4641 // stop the question. 4642 // 4643 // CurrentQuestion is used by RmvEventsForQuestion below. While delivering RMV events, the 4644 // application callback can potentially stop the current question (detected by CurrentQuestion) or 4645 // *any* other question which could be the next one that we may process here. RestartQuestion 4646 // points to the "next" question which will be automatically advanced in mDNS_StopQuery_internal 4647 // if the "next" question is stopped while the CurrentQuestion is stopped 4648 4649 if (m->RestartQuestion) 4650 LogMsg("mDNSCoreRestartAddressQueries: ERROR!! m->RestartQuestion already set: %##s (%s)", 4651 m->RestartQuestion->qname.c, DNSTypeName(m->RestartQuestion->qtype)); 4652 4653 m->RestartQuestion = m->Questions; 4654 while (m->RestartQuestion) 4655 { 4656 q = m->RestartQuestion; 4657 m->RestartQuestion = q->next; 4658 // GetZoneData questions are referenced by other questions (original query that started the GetZoneData 4659 // question) through their "nta" pointer. Normally when the original query stops, it stops the 4660 // GetZoneData question and also frees the memory (See CancelGetZoneData). If we stop the GetZoneData 4661 // question followed by the original query that refers to this GetZoneData question, we will end up 4662 // freeing the GetZoneData question and then start the "freed" question at the end. 4663 4664 if (IsGetZoneDataQuestion(q)) 4665 { 4666 DNSQuestion *refq = q->next; 4667 LogInfo("mDNSCoreRestartAddressQueries: Skipping GetZoneDataQuestion %p %##s (%s)", q, q->qname.c, DNSTypeName(q->qtype)); 4668 // debug stuff, we just try to find the referencing question and don't do much with it 4669 while (refq) 4670 { 4671 if (q == &refq->nta->question) 4672 { 4673 LogInfo("mDNSCoreRestartAddressQueries: Question %p %##s (%s) referring to GetZoneDataQuestion %p, not stopping", refq, refq->qname.c, DNSTypeName(refq->qtype), q); 4674 } 4675 refq = refq->next; 4676 } 4677 continue; 4678 } 4679 4680 // This function is called when /etc/hosts changes and that could affect A, AAAA and CNAME queries 4681 if (q->qtype != kDNSType_A && q->qtype != kDNSType_AAAA && q->qtype != kDNSType_CNAME) continue; 4682 4683 // If the search domains did not change, then we restart all the queries. Otherwise, only 4684 // for queries for which we "might" have appended search domains ("might" because we may 4685 // find results before we apply search domains even though AppendSearchDomains is set to 1) 4686 if (!SearchDomainsChanged || q->AppendSearchDomains) 4687 { 4688 // NOTE: CacheRecordRmvEventsForQuestion will not generate RMV events for queries that have non-zero 4689 // LOAddressAnswers. Hence it is important that we call CacheRecordRmvEventsForQuestion before 4690 // LocalRecordRmvEventsForQuestion (which decrements LOAddressAnswers). Let us say that 4691 // /etc/hosts has an A Record for web.apple.com. Any queries for web.apple.com will be answered locally. 4692 // But this can't prevent a CNAME/AAAA query to not to be sent on the wire. When it is sent on the wire, 4693 // it could create cache entries. When we are restarting queries, we can't deliver the cache RMV events 4694 // for the original query using these cache entries as ADDs were never delivered using these cache 4695 // entries and hence this order is needed. 4696 4697 // If the query is suppressed, the RMV events won't be delivered 4698 if (!CacheRecordRmvEventsForQuestion(m, q)) { LogInfo("mDNSCoreRestartAddressQueries: Question deleted while delivering Cache Record RMV events"); continue; } 4699 4700 // SuppressQuery status does not affect questions that are answered using local records 4701 if (!LocalRecordRmvEventsForQuestion(m, q)) { LogInfo("mDNSCoreRestartAddressQueries: Question deleted while delivering Local Record RMV events"); continue; } 4702 4703 LogInfo("mDNSCoreRestartAddressQueries: Stop question %p %##s (%s), AppendSearchDomains %d, qnameOrig %p", q, 4704 q->qname.c, DNSTypeName(q->qtype), q->AppendSearchDomains, q->qnameOrig); 4705 mDNS_StopQuery_internal(m, q); 4706 // Reset state so that it looks like it was in the beginning i.e it should look at /etc/hosts, cache 4707 // and then search domains should be appended. At the beginning, qnameOrig was NULL. 4708 if (q->qnameOrig) 4709 { 4710 LogInfo("mDNSCoreRestartAddressQueries: qnameOrig %##s", q->qnameOrig); 4711 AssignDomainName(&q->qname, q->qnameOrig); 4712 mDNSPlatformMemFree(q->qnameOrig); 4713 q->qnameOrig = mDNSNULL; 4714 q->RetryWithSearchDomains = ApplySearchDomainsFirst(q) ? 1 : 0; 4715 } 4716 q->SearchListIndex = 0; 4717 q->next = restart; 4718 restart = q; 4719 } 4720 } 4721 4722 // 3. Callback before we start the query 4723 if (BeforeStartCallback) BeforeStartCallback(m, context); 4724 4725 // 4. Restart all the stopped queries 4726 while (restart) 4727 { 4728 q = restart; 4729 restart = restart->next; 4730 q->next = mDNSNULL; 4731 LogInfo("mDNSCoreRestartAddressQueries: Start question %p %##s (%s)", q, q->qname.c, DNSTypeName(q->qtype)); 4732 mDNS_StartQuery_internal(m, q); 4733 } 4734 } 4735 4736 mDNSexport void mDNSCoreRestartQueries(mDNS *const m) 4737 { 4738 DNSQuestion *q; 4739 4740 #ifndef UNICAST_DISABLED 4741 // Retrigger all our uDNS questions 4742 if (m->CurrentQuestion) 4743 LogMsg("mDNSCoreRestartQueries: ERROR m->CurrentQuestion already set: %##s (%s)", 4744 m->CurrentQuestion->qname.c, DNSTypeName(m->CurrentQuestion->qtype)); 4745 m->CurrentQuestion = m->Questions; 4746 while (m->CurrentQuestion) 4747 { 4748 q = m->CurrentQuestion; 4749 m->CurrentQuestion = m->CurrentQuestion->next; 4750 if (!mDNSOpaque16IsZero(q->TargetQID) && ActiveQuestion(q)) ActivateUnicastQuery(m, q, mDNStrue); 4751 } 4752 #endif 4753 4754 // Retrigger all our mDNS questions 4755 for (q = m->Questions; q; q=q->next) // Scan our list of questions 4756 if (mDNSOpaque16IsZero(q->TargetQID) && ActiveQuestion(q)) 4757 { 4758 q->ThisQInterval = InitialQuestionInterval; // MUST be > zero for an active question 4759 q->RequestUnicast = 2; // Set to 2 because is decremented once *before* we check it 4760 q->LastQTime = m->timenow - q->ThisQInterval; 4761 q->RecentAnswerPkts = 0; 4762 ExpireDupSuppressInfo(q->DupSuppress, m->timenow); 4763 m->NextScheduledQuery = m->timenow; 4764 } 4765 } 4766 4767 // *************************************************************************** 4768 #if COMPILER_LIKES_PRAGMA_MARK 4769 #pragma mark - 4770 #pragma mark - Power Management (Sleep/Wake) 4771 #endif 4772 4773 mDNSexport void mDNS_UpdateAllowSleep(mDNS *const m) 4774 { 4775 #ifndef IDLESLEEPCONTROL_DISABLED 4776 mDNSBool allowSleep = mDNStrue; 4777 char reason[128]; 4778 4779 reason[0] = 0; 4780 4781 if (m->SystemSleepOnlyIfWakeOnLAN) 4782 { 4783 // Don't sleep if we are a proxy for any services 4784 if (m->ProxyRecords) 4785 { 4786 allowSleep = mDNSfalse; 4787 mDNS_snprintf(reason, sizeof(reason), "sleep proxy for %d records", m->ProxyRecords); 4788 LogInfo("Sleep disabled because we are proxying %d records", m->ProxyRecords); 4789 } 4790 4791 if (allowSleep && mDNSCoreHaveAdvertisedMulticastServices(m)) 4792 { 4793 // Scan the list of active interfaces 4794 NetworkInterfaceInfo *intf; 4795 for (intf = GetFirstActiveInterface(m->HostInterfaces); intf; intf = GetFirstActiveInterface(intf->next)) 4796 { 4797 if (intf->McastTxRx && !intf->Loopback) 4798 { 4799 // Disallow sleep if this interface doesn't support NetWake 4800 if (!intf->NetWake) 4801 { 4802 allowSleep = mDNSfalse; 4803 mDNS_snprintf(reason, sizeof(reason), "%s does not support NetWake", intf->ifname); 4804 LogInfo("Sleep disabled because %s does not support NetWake", intf->ifname); 4805 break; 4806 } 4807 4808 // Disallow sleep if there is no sleep proxy server 4809 if (FindSPSInCache1(m, &intf->NetWakeBrowse, mDNSNULL, mDNSNULL) == mDNSNULL) 4810 { 4811 allowSleep = mDNSfalse; 4812 mDNS_snprintf(reason, sizeof(reason), "%s does not support NetWake", intf->ifname); 4813 LogInfo("Sleep disabled because %s has no sleep proxy", intf->ifname); 4814 break; 4815 } 4816 } 4817 } 4818 } 4819 } 4820 4821 // Call the platform code to enable/disable sleep 4822 mDNSPlatformSetAllowSleep(m, allowSleep, reason); 4823 #endif /* !defined(IDLESLEEPCONTROL_DISABLED) */ 4824 } 4825 4826 mDNSlocal void SendSPSRegistrationForOwner(mDNS *const m, NetworkInterfaceInfo *const intf, const mDNSOpaque16 id, const OwnerOptData *const owner) 4827 { 4828 const int optspace = DNSOpt_Header_Space + DNSOpt_LeaseData_Space + DNSOpt_Owner_Space(&m->PrimaryMAC, &intf->MAC); 4829 const int sps = intf->NextSPSAttempt / 3; 4830 AuthRecord *rr; 4831 4832 if (!intf->SPSAddr[sps].type) 4833 { 4834 intf->NextSPSAttemptTime = m->timenow + mDNSPlatformOneSecond; 4835 if (m->NextScheduledSPRetry - intf->NextSPSAttemptTime > 0) 4836 m->NextScheduledSPRetry = intf->NextSPSAttemptTime; 4837 LogSPS("SendSPSRegistration: %s SPS %d (%d) %##s not yet resolved", intf->ifname, intf->NextSPSAttempt, sps, intf->NetWakeResolve[sps].qname.c); 4838 goto exit; 4839 } 4840 4841 // Mark our mDNS records (not unicast records) for transfer to SPS 4842 if (mDNSOpaque16IsZero(id)) 4843 for (rr = m->ResourceRecords; rr; rr=rr->next) 4844 if (rr->resrec.RecordType > kDNSRecordTypeDeregistering) 4845 if (rr->resrec.InterfaceID == intf->InterfaceID || (!rr->resrec.InterfaceID && (rr->ForceMCast || IsLocalDomain(rr->resrec.name)))) 4846 if (mDNSPlatformMemSame(owner, &rr->WakeUp, sizeof(*owner))) 4847 rr->SendRNow = mDNSInterfaceMark; // mark it now 4848 4849 while (1) 4850 { 4851 mDNSu8 *p = m->omsg.data; 4852 // To comply with RFC 2782, PutResourceRecord suppresses name compression for SRV records in unicast updates. 4853 // For now we follow that same logic for SPS registrations too. 4854 // If we decide to compress SRV records in SPS registrations in the future, we can achieve that by creating our 4855 // initial DNSMessage with h.flags set to zero, and then update it to UpdateReqFlags right before sending the packet. 4856 InitializeDNSMessage(&m->omsg.h, mDNSOpaque16IsZero(id) ? mDNS_NewMessageID(m) : id, UpdateReqFlags); 4857 4858 for (rr = m->ResourceRecords; rr; rr=rr->next) 4859 if (rr->SendRNow || (!mDNSOpaque16IsZero(id) && !AuthRecord_uDNS(rr) && mDNSSameOpaque16(rr->updateid, id) && m->timenow - (rr->LastAPTime + rr->ThisAPInterval) >= 0)) 4860 if (mDNSPlatformMemSame(owner, &rr->WakeUp, sizeof(*owner))) 4861 { 4862 mDNSu8 *newptr; 4863 const mDNSu8 *const limit = m->omsg.data + (m->omsg.h.mDNS_numUpdates ? NormalMaxDNSMessageData : AbsoluteMaxDNSMessageData) - optspace; 4864 if (rr->resrec.RecordType & kDNSRecordTypeUniqueMask) 4865 rr->resrec.rrclass |= kDNSClass_UniqueRRSet; // Temporarily set the 'unique' bit so PutResourceRecord will set it 4866 newptr = PutResourceRecordTTLWithLimit(&m->omsg, p, &m->omsg.h.mDNS_numUpdates, &rr->resrec, rr->resrec.rroriginalttl, limit); 4867 rr->resrec.rrclass &= ~kDNSClass_UniqueRRSet; // Make sure to clear 'unique' bit back to normal state 4868 if (!newptr) 4869 LogSPS("SendSPSRegistration put %s FAILED %d/%d %s", intf->ifname, p - m->omsg.data, limit - m->omsg.data, ARDisplayString(m, rr)); 4870 else 4871 { 4872 LogSPS("SendSPSRegistration put %s %s", intf->ifname, ARDisplayString(m, rr)); 4873 rr->SendRNow = mDNSNULL; 4874 rr->ThisAPInterval = mDNSPlatformOneSecond; 4875 rr->LastAPTime = m->timenow; 4876 rr->updateid = m->omsg.h.id; 4877 if (m->NextScheduledResponse - (rr->LastAPTime + rr->ThisAPInterval) >= 0) 4878 m->NextScheduledResponse = (rr->