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