1 /* -*- Mode: C; tab-width: 4 -*- 2 * 3 * Copyright (c) 2003-2004 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 File: daemon.c 18 19 Contains: main & associated Application layer for mDNSResponder on Linux. 20 21 */ 22 23 #if __APPLE__ 24 // In Mac OS X 10.5 and later trying to use the daemon function gives a daemon is deprecated 25 // error, which prevents compilation because we build with "-Werror". 26 // Since this is supposed to be portable cross-platform code, we don't care that daemon is 27 // deprecated on Mac OS X 10.5, so we use this preprocessor trick to eliminate the error message. 28 #define daemon yes_we_know_that_daemon_is_deprecated_in_os_x_10_5_thankyou 29 #endif 30 31 #include <stdio.h> 32 #include <string.h> 33 #include <unistd.h> 34 #include <stdlib.h> 35 #include <signal.h> 36 #include <errno.h> 37 #include <fcntl.h> 38 #include <pwd.h> 39 #include <sys/types.h> 40 41 #if __APPLE__ 42 #undef daemon 43 extern int daemon(int, int); 44 #endif 45 46 #include "mDNSEmbeddedAPI.h" 47 #include "mDNSPosix.h" 48 #include "mDNSUNP.h" // For daemon() 49 #include "uds_daemon.h" 50 #include "PlatformCommon.h" 51 52 #ifndef MDNS_USERNAME 53 #define MDNS_USERNAME "nobody" 54 #endif 55 56 #ifdef __ANDROID__ 57 #include <cutils/sockets.h> 58 #endif 59 60 #define CONFIG_FILE "/etc/mdnsd.conf" 61 static domainname DynDNSZone; // Default wide-area zone for service registration 62 static domainname DynDNSHostname; 63 64 #define RR_CACHE_SIZE 500 65 static CacheEntity gRRCache[RR_CACHE_SIZE]; 66 static mDNS_PlatformSupport PlatformStorage; 67 68 mDNSlocal void mDNS_StatusCallback(mDNS *const m, mStatus result) 69 { 70 (void)m; // Unused 71 if (result == mStatus_NoError) 72 { 73 // On successful registration of dot-local mDNS host name, daemon may want to check if 74 // any name conflict and automatic renaming took place, and if so, record the newly negotiated 75 // name in persistent storage for next time. It should also inform the user of the name change. 76 // On Mac OS X we store the current dot-local mDNS host name in the SCPreferences store, 77 // and notify the user with a CFUserNotification. 78 } 79 else if (result == mStatus_ConfigChanged) 80 { 81 udsserver_handle_configchange(m); 82 } 83 else if (result == mStatus_GrowCache) 84 { 85 // Allocate another chunk of cache storage 86 CacheEntity *storage = malloc(sizeof(CacheEntity) * RR_CACHE_SIZE); 87 if (storage) mDNS_GrowCache(m, storage, RR_CACHE_SIZE); 88 } 89 } 90 91 // %%% Reconfigure() probably belongs in the platform support layer (mDNSPosix.c), not the daemon cde 92 // -- all client layers running on top of mDNSPosix.c need to handle network configuration changes, 93 // not only the Unix Domain Socket Daemon 94 95 static void Reconfigure(mDNS *m) 96 { 97 mDNSAddr DynDNSIP; 98 const mDNSAddr dummy = { mDNSAddrType_IPv4, { { { 1, 1, 1, 1 } } } };; 99 mDNS_SetPrimaryInterfaceInfo(m, NULL, NULL, NULL); 100 if (ParseDNSServers(m, uDNS_SERVERS_FILE) < 0) 101 LogMsg("Unable to parse DNS server list. Unicast DNS-SD unavailable"); 102 ReadDDNSSettingsFromConfFile(m, CONFIG_FILE, &DynDNSHostname, &DynDNSZone, NULL); 103 mDNSPlatformSourceAddrForDest(&DynDNSIP, &dummy); 104 if (DynDNSHostname.c[0]) mDNS_AddDynDNSHostName(m, &DynDNSHostname, NULL, NULL); 105 if (DynDNSIP.type) mDNS_SetPrimaryInterfaceInfo(m, &DynDNSIP, NULL, NULL); 106 mDNS_ConfigChanged(m); 107 } 108 109 // Do appropriate things at startup with command line arguments. Calls exit() if unhappy. 110 mDNSlocal void ParseCmdLinArgs(int argc, char **argv) 111 { 112 if (argc > 1) 113 { 114 if (0 == strcmp(argv[1], "-debug")) mDNS_DebugMode = mDNStrue; 115 else printf("Usage: %s [-debug]\n", argv[0]); 116 } 117 #ifndef __ANDROID__ 118 if (!mDNS_DebugMode) 119 { 120 int result = daemon(0, 0); 121 if (result != 0) { LogMsg("Could not run as daemon - exiting"); exit(result); } 122 #if __APPLE__ 123 LogMsg("The POSIX mdnsd should only be used on OS X for testing - exiting"); 124 exit(-1); 125 #endif 126 } 127 #endif // !__ANDROID__ 128 } 129 130 mDNSlocal void DumpStateLog(mDNS *const m) 131 // Dump a little log of what we've been up to. 132 { 133 LogMsg("---- BEGIN STATE LOG ----"); 134 udsserver_info(m); 135 LogMsg("---- END STATE LOG ----"); 136 } 137 138 mDNSlocal mStatus MainLoop(mDNS *m) // Loop until we quit. 139 { 140 sigset_t signals; 141 mDNSBool gotData = mDNSfalse; 142 143 mDNSPosixListenForSignalInEventLoop(SIGINT); 144 mDNSPosixListenForSignalInEventLoop(SIGTERM); 145 mDNSPosixListenForSignalInEventLoop(SIGUSR1); 146 mDNSPosixListenForSignalInEventLoop(SIGPIPE); 147 mDNSPosixListenForSignalInEventLoop(SIGHUP) ; 148 149 for (; ;) 150 { 151 // Work out how long we expect to sleep before the next scheduled task 152 struct timeval timeout; 153 mDNSs32 ticks; 154 155 // Only idle if we didn't find any data the last time around 156 if (!gotData) 157 { 158 mDNSs32 nextTimerEvent = mDNS_Execute(m); 159 nextTimerEvent = udsserver_idle(nextTimerEvent); 160 ticks = nextTimerEvent - mDNS_TimeNow(m); 161 if (ticks < 1) ticks = 1; 162 } 163 else // otherwise call EventLoop again with 0 timemout 164 ticks = 0; 165 166 timeout.tv_sec = ticks / mDNSPlatformOneSecond; 167 timeout.tv_usec = (ticks % mDNSPlatformOneSecond) * 1000000 / mDNSPlatformOneSecond; 168 169 (void) mDNSPosixRunEventLoopOnce(m, &timeout, &signals, &gotData); 170 171 if (sigismember(&signals, SIGHUP )) Reconfigure(m); 172 if (sigismember(&signals, SIGUSR1)) DumpStateLog(m); 173 // SIGPIPE happens when we try to write to a dead client; death should be detected soon in request_callback() and cleaned up. 174 if (sigismember(&signals, SIGPIPE)) LogMsg("Received SIGPIPE - ignoring"); 175 if (sigismember(&signals, SIGINT) || sigismember(&signals, SIGTERM)) break; 176 } 177 return EINTR; 178 } 179 180 int main(int argc, char **argv) 181 { 182 mStatus err; 183 184 ParseCmdLinArgs(argc, argv); 185 186 LogMsg("%s starting", mDNSResponderVersionString); 187 188 err = mDNS_Init(&mDNSStorage, &PlatformStorage, gRRCache, RR_CACHE_SIZE, mDNS_Init_AdvertiseLocalAddresses, 189 mDNS_StatusCallback, mDNS_Init_NoInitCallbackContext); 190 191 if (mStatus_NoError == err) 192 #ifdef __ANDROID__ 193 { 194 dnssd_sock_t s[1]; 195 char *socketname = strrchr(MDNS_UDS_SERVERPATH, '/'); 196 if (socketname) 197 { 198 socketname++; // skip '/' 199 s[0] = android_get_control_socket(socketname); 200 err = udsserver_init(s, 1); 201 } else { 202 err = udsserver_init(mDNSNULL, 0); 203 } 204 } 205 #else 206 err = udsserver_init(mDNSNULL, 0); 207 #endif // __ANDROID__ 208 209 Reconfigure(&mDNSStorage); 210 211 // Now that we're finished with anything privileged, switch over to running as "nobody" 212 if (mStatus_NoError == err) 213 { 214 const struct passwd *pw = getpwnam(MDNS_USERNAME); 215 if (pw != NULL) 216 setuid(pw->pw_uid); 217 else 218 LogMsg("WARNING: mdnsd continuing as root because user \"%s\" does not exist", MDNS_USERNAME); 219 } 220 221 if (mStatus_NoError == err) 222 err = MainLoop(&mDNSStorage); 223 224 LogMsg("%s stopping", mDNSResponderVersionString); 225 226 mDNS_Close(&mDNSStorage); 227 228 if (udsserver_exit() < 0) 229 LogMsg("ExitCallback: udsserver_exit failed"); 230 231 #if MDNS_DEBUGMSGS > 0 232 printf("mDNSResponder exiting normally with %ld\n", err); 233 #endif 234 235 return err; 236 } 237 238 // uds_daemon support //////////////////////////////////////////////////////////// 239 240 mStatus udsSupportAddFDToEventLoop(int fd, udsEventCallback callback, void *context, void **platform_data) 241 /* Support routine for uds_daemon.c */ 242 { 243 // Depends on the fact that udsEventCallback == mDNSPosixEventCallback 244 (void) platform_data; 245 return mDNSPosixAddFDToEventLoop(fd, callback, context); 246 } 247 248 int udsSupportReadFD(dnssd_sock_t fd, char *buf, int len, int flags, void *platform_data) 249 { 250 (void) platform_data; 251 return recv(fd, buf, len, flags); 252 } 253 254 mStatus udsSupportRemoveFDFromEventLoop(int fd, void *platform_data) // Note: This also CLOSES the file descriptor 255 { 256 mStatus err = mDNSPosixRemoveFDFromEventLoop(fd); 257 (void) platform_data; 258 close(fd); 259 return err; 260 } 261 262 mDNSexport void RecordUpdatedNiceLabel(mDNS *const m, mDNSs32 delay) 263 { 264 (void)m; 265 (void)delay; 266 // No-op, for now 267 } 268 269 #if _BUILDING_XCODE_PROJECT_ 270 // If the process crashes, then this string will be magically included in the automatically-generated crash log 271 const char *__crashreporter_info__ = mDNSResponderVersionString_SCCS + 5; 272 asm(".desc ___crashreporter_info__, 0x10"); 273 #endif 274 275 // For convenience when using the "strings" command, this is the last thing in the file 276 #if mDNSResponderVersion > 1 277 mDNSexport const char mDNSResponderVersionString_SCCS[] = "@(#) mDNSResponder-" STRINGIFY(mDNSResponderVersion) " (" __DATE__ " " __TIME__ ")"; 278 #elif MDNS_VERSIONSTR_NODTS 279 mDNSexport const char mDNSResponderVersionString_SCCS[] = "@(#) mDNSResponder (Engineering Build)"; 280 #else 281 mDNSexport const char mDNSResponderVersionString_SCCS[] = "@(#) mDNSResponder (Engineering Build) (" __DATE__ " " __TIME__ ")"; 282 #endif 283
