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