mDNSPosix/PosixDaemon.c

   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         Change History (most recent first):
  22
  23 $Log: PosixDaemon.c,v $
  24 Revision 1.43  2007/10/22 20:05:34  cheshire
  25 Use mDNSPlatformSourceAddrForDest instead of FindSourceAddrForIP
  26
  27 Revision 1.42  2007/09/18 19:09:02  cheshire
  28 <rdar://problem/5489549> mDNSResponderHelper (and other binaries) missing SCCS version strings
  29
  30 Revision 1.41  2007/09/04 17:02:25  cheshire
  31 <rdar://problem/5458929> False positives in changed files list in nightly builds
  32 Added MDNS_VERSIONSTR_NODTS option at the reqest of Rishi Srivatsavai (Sun)
  33
  34 Revision 1.40  2007/07/31 23:08:34  mcguire
  35 <rdar://problem/5329542> BTMM: Make AutoTunnel mode work with multihoming
  36
  37 Revision 1.39  2007/03/21 00:30:44  cheshire
  38 Remove obsolete mDNS_DeleteDNSServers() call
  39
  40 Revision 1.38  2007/02/14 01:58:19  cheshire
  41 <rdar://problem/4995831> Don't delete Unix Domain Socket on exit if we didn't create it on startup
  42
  43 Revision 1.37  2007/02/07 19:32:00  cheshire
  44 <rdar://problem/4980353> All mDNSResponder components should contain version strings in SCCS-compatible format
  45
  46 Revision 1.36  2007/02/06 19:06:48  cheshire
  47 <rdar://problem/3956518> Need to go native with launchd
  48
  49 Revision 1.35  2007/01/05 08:30:52  cheshire
  50 Trim excessive "$Log" checkin history from before 2006
  51 (checkin history still available via "cvs log ..." of course)
  52
  53 Revision 1.34  2007/01/05 05:46:08  cheshire
  54 Add mDNS *const m parameter to udsserver_handle_configchange()
  55
  56 Revision 1.33  2006/12/21 00:10:53  cheshire
  57 Make mDNS_PlatformSupport PlatformStorage a static global instead of a stack variable
  58
  59 Revision 1.32  2006/11/03 22:28:50  cheshire
  60 PosixDaemon needs to handle mStatus_ConfigChanged and mStatus_GrowCache messages
  61
  62 Revision 1.31  2006/08/14 23:24:46  cheshire
  63 Re-licensed mDNSResponder daemon source code under Apache License, Version 2.0
  64
  65 Revision 1.30  2006/07/07 01:09:12  cheshire
  66 <rdar://problem/4472013> Add Private DNS server functionality to dnsextd
  67 Only use mallocL/freeL debugging routines when building mDNSResponder, not dnsextd
  68
  69 */
  70
  71 #include <stdio.h>
  72 #include <string.h>
  73 #include <unistd.h>
  74 #include <stdlib.h>
  75 #include <signal.h>
  76 #include <errno.h>
  77 #include <fcntl.h>
  78 #include <pwd.h>
  79 #include <sys/types.h>
  80
  81 #include "mDNSEmbeddedAPI.h"
  82 #include "mDNSDebug.h"
  83 #include "mDNSPosix.h"
  84 #include "uds_daemon.h"
  85 #include "PlatformCommon.h"
  86
  87 #define CONFIG_FILE "/etc/mdnsd.conf"
  88 static domainname DynDNSZone;                // Default wide-area zone for service registration
  89 static domainname DynDNSHostname;
  90
  91 #define RR_CACHE_SIZE 500
  92 static CacheEntity gRRCache[RR_CACHE_SIZE];
  93 static mDNS_PlatformSupport PlatformStorage;
  94
  95 mDNSlocal void mDNS_StatusCallback(mDNS *const m, mStatus result)
  96         {
  97         (void)m; // Unused
  98         if (result == mStatus_NoError)
  99                 {
 100                 // On successful registration of dot-local mDNS host name, daemon may want to check if
 101                 // any name conflict and automatic renaming took place, and if so, record the newly negotiated
 102                 // name in persistent storage for next time. It should also inform the user of the name change.
 103                 // On Mac OS X we store the current dot-local mDNS host name in the SCPreferences store,
 104                 // and notify the user with a CFUserNotification.
 105                 }
 106         else if (result == mStatus_ConfigChanged)
 107                 {
 108                 udsserver_handle_configchange(m);
 109                 }
 110         else if (result == mStatus_GrowCache)
 111                 {
 112                 // Allocate another chunk of cache storage
 113                 CacheEntity *storage = malloc(sizeof(CacheEntity) * RR_CACHE_SIZE);
 114                 if (storage) mDNS_GrowCache(m, storage, RR_CACHE_SIZE);
 115                 }
 116         }
 117
 118 // %%% Reconfigure() probably belongs in the platform support layer (mDNSPosix.c), not the daemon cde
 119 // -- all client layers running on top of mDNSPosix.c need to handle network configuration changes,
 120 // not only the Unix Domain Socket Daemon
 121
 122 static void Reconfigure(mDNS *m)
 123         {
 124         mDNSAddr DynDNSIP;
 125         const mDNSAddr dummy = { mDNSAddrType_IPv4, { { { 1, 1, 1, 1 } } } };;
 126         mDNS_SetPrimaryInterfaceInfo(m, NULL, NULL, NULL);
 127         if (ParseDNSServers(m, uDNS_SERVERS_FILE) < 0)
 128                 LogMsg("Unable to parse DNS server list. Unicast DNS-SD unavailable");
 129         ReadDDNSSettingsFromConfFile(m, CONFIG_FILE, &DynDNSHostname, &DynDNSZone, NULL);
 130         mDNSPlatformSourceAddrForDest(&DynDNSIP, &dummy);
 131         if (DynDNSHostname.c[0]) mDNS_AddDynDNSHostName(m, &DynDNSHostname, NULL, NULL);
 132         if (DynDNSIP.type)       mDNS_SetPrimaryInterfaceInfo(m, &DynDNSIP, NULL, NULL);
 133         m->MainCallback(m, mStatus_ConfigChanged);
 134         }
 135
 136 // Do appropriate things at startup with command line arguments. Calls exit() if unhappy.
 137 mDNSlocal void ParseCmdLinArgs(int argc, char **argv)
 138         {
 139         if (argc > 1)
 140                 {
 141                 if (0 == strcmp(argv[1], "-debug")) mDNS_DebugMode = mDNStrue;
 142                 else printf("Usage: %s [-debug]\n", argv[0]);
 143                 }
 144
 145         if (!mDNS_DebugMode)
 146                 {
 147                 int result = daemon(0, 0);
 148                 if (result != 0) { LogMsg("Could not run as daemon - exiting"); exit(result); }
 149 #if __APPLE__
 150                 LogMsg("The POSIX mdnsd should only be used on OS X for testing - exiting");
 151                 exit(-1);
 152 #endif
 153                 }
 154         }
 155
 156 mDNSlocal void DumpStateLog(mDNS *const m)
 157 // Dump a little log of what we've been up to.
 158         {
 159         LogMsgIdent(mDNSResponderVersionString, "---- BEGIN STATE LOG ----");
 160         udsserver_info(m);
 161         LogMsgIdent(mDNSResponderVersionString, "----  END STATE LOG  ----");
 162         }
 163
 164 mDNSlocal mStatus MainLoop(mDNS *m) // Loop until we quit.
 165         {
 166         sigset_t        signals;
 167         mDNSBool        gotData = mDNSfalse;
 168
 169         mDNSPosixListenForSignalInEventLoop(SIGINT);
 170         mDNSPosixListenForSignalInEventLoop(SIGTERM);
 171         mDNSPosixListenForSignalInEventLoop(SIGUSR1);
 172         mDNSPosixListenForSignalInEventLoop(SIGPIPE);
 173         mDNSPosixListenForSignalInEventLoop(SIGHUP) ;
 174
 175         for (; ;)
 176                 {
 177                 // Work out how long we expect to sleep before the next scheduled task
 178                 struct timeval  timeout;
 179                 mDNSs32                 ticks;
 180
 181                 // Only idle if we didn't find any data the last time around
 182                 if (!gotData)
 183                         {
 184                         mDNSs32                 nextTimerEvent = mDNS_Execute(m);
 185                         nextTimerEvent = udsserver_idle(nextTimerEvent);
 186                         ticks = nextTimerEvent - mDNS_TimeNow(m);
 187                         if (ticks < 1) ticks = 1;
 188                         }
 189                 else    // otherwise call EventLoop again with 0 timemout
 190                         ticks = 0;
 191
 192                 timeout.tv_sec = ticks / mDNSPlatformOneSecond;
 193                 timeout.tv_usec = (ticks % mDNSPlatformOneSecond) * 1000000 / mDNSPlatformOneSecond;
 194
 195                 (void) mDNSPosixRunEventLoopOnce(m, &timeout, &signals, &gotData);
 196
 197                 if (sigismember(&signals, SIGHUP )) Reconfigure(m);
 198                 if (sigismember(&signals, SIGUSR1)) DumpStateLog(m);
 199                 // SIGPIPE happens when we try to write to a dead client; death should be detected soon in request_callback() and cleaned up.
 200                 if (sigismember(&signals, SIGPIPE)) LogMsg("Received SIGPIPE - ignoring");
 201                 if (sigismember(&signals, SIGINT) || sigismember(&signals, SIGTERM)) break;
 202                 }
 203         return EINTR;
 204         }
 205
 206 int main(int argc, char **argv)
 207         {
 208         mStatus                                 err;
 209
 210         ParseCmdLinArgs(argc, argv);
 211
 212         LogMsgIdent(mDNSResponderVersionString, "starting");
 213
 214         err = mDNS_Init(&mDNSStorage, &PlatformStorage, gRRCache, RR_CACHE_SIZE, mDNS_Init_AdvertiseLocalAddresses,
 215                                         mDNS_StatusCallback, mDNS_Init_NoInitCallbackContext);
 216
 217         if (mStatus_NoError == err)
 218                 err = udsserver_init(dnssd_InvalidSocket);
 219
 220         Reconfigure(&mDNSStorage);
 221
 222         // Now that we're finished with anything privileged, switch over to running as "nobody"
 223         if (mStatus_NoError == err)
 224                 {
 225                 const struct passwd *pw = getpwnam("nobody");
 226                 if (pw != NULL)
 227                         setuid(pw->pw_uid);
 228                 else
 229                         LogMsg("WARNING: mdnsd continuing as root because user \"nobody\" does not exist");
 230                 }
 231
 232         if (mStatus_NoError == err)
 233                 err = MainLoop(&mDNSStorage);
 234
 235         LogMsgIdent(mDNSResponderVersionString, "stopping");
 236
 237         mDNS_Close(&mDNSStorage);
 238
 239         if (udsserver_exit(dnssd_InvalidSocket) < 0)
 240                 LogMsg("ExitCallback: udsserver_exit failed");
 241
 242  #if MDNS_DEBUGMSGS > 0
 243         printf("mDNSResponder exiting normally with %ld\n", err);
 244  #endif
 245
 246         return err;
 247         }
 248
 249 //              uds_daemon support              ////////////////////////////////////////////////////////////
 250
 251 mStatus udsSupportAddFDToEventLoop(int fd, udsEventCallback callback, void *context)
 252 /* Support routine for uds_daemon.c */
 253         {
 254         // Depends on the fact that udsEventCallback == mDNSPosixEventCallback
 255         return mDNSPosixAddFDToEventLoop(fd, callback, context);
 256         }
 257
 258 mStatus udsSupportRemoveFDFromEventLoop(int fd)         // Note: This also CLOSES the file descriptor
 259         {
 260         mStatus err = mDNSPosixRemoveFDFromEventLoop(fd);
 261         close(fd);
 262         return err;
 263         }
 264
 265 mDNSexport void RecordUpdatedNiceLabel(mDNS *const m, mDNSs32 delay)
 266         {
 267         (void)m;
 268         (void)delay;
 269         // No-op, for now
 270         }
 271
 272 // If the process crashes, then this string will be magically included in the automatically-generated crash log
 273 const char *__crashreporter_info__ = mDNSResponderVersionString_SCCS + 5;
 274 asm(".desc ___crashreporter_info__, 0x10");
 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