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 MDNSD_USER 53 #define MDNSD_USER "nobody" 54 #endif 55 56 #define CONFIG_FILE "/etc/mdnsd.conf" 57 static domainname DynDNSZone; // Default wide-area zone for service registration 58 static domainname DynDNSHostname; 59 60 #define RR_CACHE_SIZE 500 61 static CacheEntity gRRCache[RR_CACHE_SIZE]; 62 static mDNS_PlatformSupport PlatformStorage; 63 64 mDNSlocal void mDNS_StatusCallback(mDNS *const m, mStatus result) 65 { 66 (void)m; // Unused 67 if (result == mStatus_NoError) 68 { 69 // On successful registration of dot-local mDNS host name, daemon may want to check if 70 // any name conflict and automatic renaming took place, and if so, record the newly negotiated 71 // name in persistent storage for next time. It should also inform the user of the name change. 72 // On Mac OS X we store the current dot-local mDNS host name in the SCPreferences store, 73 // and notify the user with a CFUserNotification. 74 } 75 else if (result == mStatus_ConfigChanged) 76 { 77 udsserver_handle_configchange(m); 78 } 79 else if (result == mStatus_GrowCache) 80 { 81 // Allocate another chunk of cache storage 82 CacheEntity *storage = malloc(sizeof(CacheEntity) * RR_CACHE_SIZE); 83 if (storage) mDNS_GrowCache(m, storage, RR_CACHE_SIZE); 84 } 85 } 86 87 // %%% Reconfigure() probably belongs in the platform support layer (mDNSPosix.c), not the daemon cde 88 // -- all client layers running on top of mDNSPosix.c need to handle network configuration changes, 89 // not only the Unix Domain Socket Daemon 90 91 static void Reconfigure(mDNS *m) 92 { 93 mDNSAddr DynDNSIP; 94 const mDNSAddr dummy = { mDNSAddrType_IPv4, { { { 1, 1, 1, 1 } } } };; 95 mDNS_SetPrimaryInterfaceInfo(m, NULL, NULL, NULL); 96 if (ParseDNSServers(m, uDNS_SERVERS_FILE) < 0) 97 LogMsg("Unable to parse DNS server list. Unicast DNS-SD unavailable"); 98 ReadDDNSSettingsFromConfFile(m, CONFIG_FILE, &DynDNSHostname, &DynDNSZone, NULL); 99 mDNSPlatformSourceAddrForDest(&DynDNSIP, &dummy); 100 if (DynDNSHostname.c[0]) mDNS_AddDynDNSHostName(m, &DynDNSHostname, NULL, NULL); 101 if (DynDNSIP.type) mDNS_SetPrimaryInterfaceInfo(m, &DynDNSIP, NULL, NULL); 102 mDNS_ConfigChanged(m); 103 } 104 105 // Do appropriate things at startup with command line arguments. Calls exit() if unhappy. 106 mDNSlocal void ParseCmdLinArgs(int argc, char **argv) 107 { 108 if (argc > 1) 109 { 110 if (0 == strcmp(argv[1], "-debug")) mDNS_DebugMode = mDNStrue; 111 else printf("Usage: %s [-debug]\n", argv[0]); 112 } 113 114 if (!mDNS_DebugMode) 115 { 116 int result = daemon(0, 0); 117 if (result != 0) { LogMsg("Could not run as daemon - exiting"); exit(result); } 118 #if __APPLE__ 119 LogMsg("The POSIX mdnsd should only be used on OS X for testing - exiting"); 120 exit(-1); 121 #endif 122 } 123 } 124 125 mDNSlocal void ToggleLog(void) 126 { 127 mDNS_LoggingEnabled = !mDNS_LoggingEnabled; 128 } 129 130 mDNSlocal void ToggleLogPacket(void) 131 { 132 mDNS_PacketLoggingEnabled = !mDNS_PacketLoggingEnabled; 133 } 134 135 mDNSlocal void DumpStateLog(mDNS *const m) 136 // Dump a little log of what we've been up to. 137 { 138 LogMsg("---- BEGIN STATE LOG ----"); 139 udsserver_info(m); 140 LogMsg("---- END STATE LOG ----"); 141 } 142 143 mDNSlocal mStatus MainLoop(mDNS *m) // Loop until we quit. 144 { 145 sigset_t signals; 146 mDNSBool gotData = mDNSfalse; 147 148 mDNSPosixListenForSignalInEventLoop(SIGINT); 149 mDNSPosixListenForSignalInEventLoop(SIGTERM); 150 mDNSPosixListenForSignalInEventLoop(SIGUSR1); 151 mDNSPosixListenForSignalInEventLoop(SIGUSR2); 152 mDNSPosixListenForSignalInEventLoop(SIGINFO); 153 mDNSPosixListenForSignalInEventLoop(SIGPIPE); 154 mDNSPosixListenForSignalInEventLoop(SIGHUP) ; 155 156 for (; ;) 157 { 158 // Work out how long we expect to sleep before the next scheduled task 159 struct timeval timeout; 160 mDNSs32 ticks; 161 162 // Only idle if we didn't find any data the last time around 163 if (!gotData) 164 { 165 mDNSs32 nextTimerEvent = mDNS_Execute(m); 166 nextTimerEvent = udsserver_idle(nextTimerEvent); 167 ticks = nextTimerEvent - mDNS_TimeNow(m); 168 if (ticks < 1) ticks = 1; 169 } 170 else // otherwise call EventLoop again with 0 timemout 171 ticks = 0; 172 173 timeout.tv_sec = ticks / mDNSPlatformOneSecond; 174 timeout.tv_usec = (ticks % mDNSPlatformOneSecond) * 1000000 / mDNSPlatformOneSecond; 175 176 (void) mDNSPosixRunEventLoopOnce(m, &timeout, &signals, &gotData); 177 178 if (sigismember(&signals, SIGHUP )) Reconfigure(m); 179 if (sigismember(&signals, SIGINFO)) DumpStateLog(m); 180 if (sigismember(&signals, SIGUSR1)) ToggleLog(); 181 if (sigismember(&signals, SIGUSR2)) ToggleLogPacket(); 182 // SIGPIPE happens when we try to write to a dead client; death should be detected soon in request_callback() and cleaned up. 183 if (sigismember(&signals, SIGPIPE)) LogMsg("Received SIGPIPE - ignoring"); 184 if (sigismember(&signals, SIGINT) || sigismember(&signals, SIGTERM)) break; 185 } 186 return EINTR; 187 } 188 189 int main(int argc, char **argv) 190 { 191 mStatus err; 192 193 ParseCmdLinArgs(argc, argv); 194 195 LogInfo("%s starting", mDNSResponderVersionString); 196 197 err = mDNS_Init(&mDNSStorage, &PlatformStorage, gRRCache, RR_CACHE_SIZE, mDNS_Init_AdvertiseLocalAddresses, 198 mDNS_StatusCallback, mDNS_Init_NoInitCallbackContext); 199 200 if (mStatus_NoError == err) 201 err = udsserver_init(mDNSNULL, 0); 202 203 Reconfigure(&mDNSStorage); 204 205 // Now that we're finished with anything privileged, switch over to running as "nobody" 206 if (mStatus_NoError == err) 207 { 208 const struct passwd *pw = getpwnam(MDNSD_USER); 209 if (pw != NULL) 210 setuid(pw->pw_uid); 211 else 212 #ifdef MDNSD_NOROOT 213 { 214 LogMsg("WARNING: mdnsd exiting because user \""MDNSD_USER"\" does not exist"); 215 err = mStatus_Invalid; 216 } 217 #else 218 LogMsg("WARNING: mdnsd continuing as root because user \""MDNSD_USER"\" does not exist"); 219 #endif 220 } 221 222 if (mStatus_NoError == err) 223 err = MainLoop(&mDNSStorage); 224 225 LogInfo("%s stopping", mDNSResponderVersionString); 226 227 mDNS_Close(&mDNSStorage); 228 229 if (udsserver_exit() < 0) 230 LogMsg("ExitCallback: udsserver_exit failed"); 231 232 #if MDNS_DEBUGMSGS > 0 233 printf("mDNSResponder exiting normally with %ld\n", err); 234 #endif 235 236 return err; 237 } 238 239 // uds_daemon support //////////////////////////////////////////////////////////// 240 241 mStatus udsSupportAddFDToEventLoop(int fd, udsEventCallback callback, void *context, void **platform_data) 242 /* Support routine for uds_daemon.c */ 243 { 244 // Depends on the fact that udsEventCallback == mDNSPosixEventCallback 245 (void) platform_data; 246 return mDNSPosixAddFDToEventLoop(fd, callback, context); 247 } 248 249 int udsSupportReadFD(dnssd_sock_t fd, char *buf, int len, int flags, void *platform_data) 250 { 251 (void) platform_data; 252 return recv(fd, buf, len, flags); 253 } 254 255 mStatus udsSupportRemoveFDFromEventLoop(int fd, void *platform_data) // Note: This also CLOSES the file descriptor 256 { 257 mStatus err = mDNSPosixRemoveFDFromEventLoop(fd); 258 (void) platform_data; 259 close(fd); 260 return err; 261 } 262 263 mDNSexport void RecordUpdatedNiceLabel(mDNS *const m, mDNSs32 delay) 264 { 265 (void)m; 266 (void)delay; 267 // No-op, for now 268 } 269 270 #if _BUILDING_XCODE_PROJECT_ 271 // If the process crashes, then this string will be magically included in the automatically-generated crash log 272 const char *__crashreporter_info__ = mDNSResponderVersionString_SCCS + 5; 273 asm (".desc ___crashreporter_info__, 0x10"); 274 #endif 275 276 // For convenience when using the "strings" command, this is the last thing in the file 277 #if mDNSResponderVersion > 1 278 mDNSexport const char mDNSResponderVersionString_SCCS[] = "@(#) mDNSResponder-" STRINGIFY(mDNSResponderVersion) " (" __DATE__ " " __TIME__ ")"; 279 #elif MDNS_VERSIONSTR_NODTS 280 mDNSexport const char mDNSResponderVersionString_SCCS[] = "@(#) mDNSResponder (Engineering Build)"; 281 #else 282 mDNSexport const char mDNSResponderVersionString_SCCS[] = "@(#) mDNSResponder (Engineering Build) (" __DATE__ " " __TIME__ ")"; 283 #endif 284