mDNSMacOSX/helper-main.c

   1 /* -*- Mode: C; tab-width: 4 -*-
   2  *
   3  * Copyright (c) 2007 Apple 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     Change History (most recent first):
  18
  19 $Log: helper-main.c,v $
  20 Revision 1.13  2007/09/21 16:13:14  cheshire
  21 Additional Tiger compatibility fix: After bootstrap_check_in, we need to give
  22 ourselves a Mach "send" right to the port, otherwise our ten-second idle timeout
  23 mechanism is not able to send the "mDNSIdleExit" message to itself
  24
  25 Revision 1.12  2007/09/20 22:26:20  cheshire
  26 Add necessary bootstrap_check_in() in Tiger compatibility code (not used on Leopard)
  27
  28 Revision 1.11  2007/09/18 19:09:02  cheshire
  29 <rdar://problem/5489549> mDNSResponderHelper (and other binaries) missing SCCS version strings
  30
  31 Revision 1.10  2007/09/09 02:21:17  mcguire
  32 <rdar://problem/5469345> Leopard Server9A547(Insatll):mDNSResponderHelper crashing
  33
  34 Revision 1.9  2007/09/07 22:44:03  mcguire
  35 <rdar://problem/5448420> Move CFUserNotification code to mDNSResponderHelper
  36
  37 Revision 1.8  2007/09/07 22:24:36  vazquez
  38 <rdar://problem/5466301> Need to stop spewing mDNSResponderHelper logs
  39
  40 Revision 1.7  2007/08/31 18:09:32  cheshire
  41 <rdar://problem/5434050> Restore ability to run mDNSResponder on Tiger
  42
  43 Revision 1.6  2007/08/31 17:45:13  cheshire
  44 Allow maxidle time of zero, meaning "run indefinitely"
  45
  46 Revision 1.5  2007/08/31 00:09:54  cheshire
  47 Deleted extraneous whitespace (shortened code from 260 lines to 160)
  48
  49 Revision 1.4  2007/08/28 00:33:04  jgraessley
  50 <rdar://problem/5423932> Selective compilation options
  51
  52 Revision 1.3  2007/08/23 23:21:24  cheshire
  53 Tiger compatibility: Use old bootstrap_register() instead of Leopard-only bootstrap_register2()
  54
  55 Revision 1.2  2007/08/23 21:36:17  cheshire
  56 Made code layout style consistent with existing project style; added $Log header
  57
  58 Revision 1.1  2007/08/08 22:34:58  mcguire
  59 <rdar://problem/5197869> Security: Run mDNSResponder as user id mdnsresponder instead of root
  60  */
  61
  62 #define _FORTIFY_SOURCE 2
  63 #include <CoreFoundation/CoreFoundation.h>
  64 #include <sys/cdefs.h>
  65 #include <sys/time.h>
  66 #include <sys/types.h>
  67 #include <mach/mach.h>
  68 #include <mach/mach_error.h>
  69 #include <servers/bootstrap.h>
  70 #include <asl.h>
  71 #include <launch.h>
  72 #include <pwd.h>
  73 #include <pthread.h>
  74 #include <stdarg.h>
  75 #include <stdbool.h>
  76 #include <stdio.h>
  77 #include <stdlib.h>
  78 #include <time.h>
  79 #include <unistd.h>
  80 #include <Security/Security.h>
  81 #include "helper.h"
  82 #include "helper-server.h"
  83 #include "helpermsg.h"
  84 #include "helpermsgServer.h"
  85
  86 #if TARGET_OS_EMBEDDED
  87 #define NO_SECURITYFRAMEWORK 1
  88 #endif
  89
  90 #ifndef LAUNCH_JOBKEY_MACHSERVICES
  91 #define LAUNCH_JOBKEY_MACHSERVICES "MachServices"
  92 #define LAUNCH_DATA_MACHPORT 10
  93 #define launch_data_get_machport launch_data_get_fd
  94 #endif
  95
  96 union max_msg_size
  97         {
  98         union __RequestUnion__proxy_helper_subsystem req;
  99         union __ReplyUnion__proxy_helper_subsystem rep;
 100         };
 101
 102 static const mach_msg_size_t MAX_MSG_SIZE = sizeof(union max_msg_size) + MAX_TRAILER_SIZE;
 103 static aslclient logclient = NULL;
 104 static int opt_debug;
 105 static pthread_t idletimer_thread;
 106
 107 unsigned long maxidle = 10;
 108 unsigned long actualidle = 3600;
 109
 110 CFRunLoopRef gRunLoop = NULL;
 111 CFRunLoopTimerRef gTimer = NULL;
 112
 113 static void helplogv(int level, const char *fmt, va_list ap)
 114         {
 115         if (NULL == logclient) { vfprintf(stderr, fmt, ap); fflush(stderr); }
 116         else asl_vlog(logclient, NULL, level, fmt, ap);
 117         }
 118
 119 void helplog(int level, const char *fmt, ...)
 120         {
 121         va_list ap;
 122         va_start(ap, fmt);
 123         helplogv(level, fmt, ap);
 124         va_end(ap);
 125         }
 126
 127 static void initialize_logging(void)
 128         {
 129         logclient = asl_open(NULL, kmDNSHelperServiceName, (opt_debug ? ASL_OPT_STDERR : 0));
 130         if (NULL == logclient) { fprintf(stderr, "Could not initialize ASL logging.\n"); fflush(stderr); return; }
 131         if (opt_debug) asl_set_filter(logclient, ASL_FILTER_MASK_UPTO(ASL_LEVEL_DEBUG));
 132         }
 133
 134 static void initialize_id(void)
 135         {
 136         static char login[] = "_mdnsresponder";
 137         struct passwd *pwd = getpwnam(login);
 138
 139         if (!pwd) { helplog(ASL_LEVEL_ERR, "Could not find account name `%s'.  I will only help root.", login); return; }
 140         mDNSResponderUID = pwd->pw_uid;
 141         mDNSResponderGID = pwd->pw_gid;
 142         }
 143
 144 static void diediedie(CFRunLoopTimerRef timer, void *context)
 145         {
 146         debug("entry");
 147         assert(gTimer == timer);
 148         if (maxidle)
 149           (void)proxy_mDNSIdleExit((mach_port_t)context);
 150         }
 151
 152 void pause_idle_timer(void)
 153         {
 154         debug("entry");
 155         assert(gTimer);
 156         assert(gRunLoop);
 157         CFRunLoopRemoveTimer(gRunLoop, gTimer, kCFRunLoopDefaultMode);
 158         }
 159
 160 void unpause_idle_timer(void)
 161         {
 162         debug("entry");
 163         assert(gRunLoop);
 164         assert(gTimer);
 165         CFRunLoopAddTimer(gRunLoop, gTimer, kCFRunLoopDefaultMode);
 166         }
 167
 168 void update_idle_timer(void)
 169         {
 170         debug("entry");
 171         assert(gTimer);
 172         CFRunLoopTimerSetNextFireDate(gTimer, CFAbsoluteTimeGetCurrent() + actualidle);
 173         }
 174
 175 static void *idletimer(void *context)
 176         {
 177         debug("entry context=%p", context);
 178         gRunLoop = CFRunLoopGetCurrent();
 179
 180         unpause_idle_timer();
 181
 182         for (;;)
 183                 {
 184                 debug("Running CFRunLoop");
 185                 CFRunLoopRun();
 186                 sleep(1);
 187                 }
 188
 189         return NULL;
 190         }
 191
 192 static void initialize_timer(mach_port_t port)
 193         {
 194         CFRunLoopTimerContext cxt = {0, (void *)port, NULL, NULL, NULL};
 195         gTimer = CFRunLoopTimerCreate(kCFAllocatorDefault, CFAbsoluteTimeGetCurrent() + actualidle, actualidle, 0, 0, diediedie, &cxt);
 196         int err = 0;
 197
 198         debug("entry port=%p", port);
 199         if (0 != (err = pthread_create(&idletimer_thread, NULL, idletimer, (void *)port)))
 200                 helplog(ASL_LEVEL_ERR, "Could not start idletimer thread: %s", strerror(err));
 201         }
 202
 203 static mach_port_t checkin(char *service_name)
 204         {
 205         kern_return_t kr = KERN_SUCCESS;
 206         mach_port_t port = MACH_PORT_NULL;
 207         launch_data_t msg = NULL, reply = NULL, datum = NULL;
 208
 209         if (NULL == (msg = launch_data_new_string(LAUNCH_KEY_CHECKIN)))
 210                 { helplog(ASL_LEVEL_ERR, "Could not create checkin message for launchd."); goto fin; }
 211         if (NULL == (reply = launch_msg(msg)))
 212                 { helplog(ASL_LEVEL_ERR, "Could not message launchd."); goto fin; }
 213         if (LAUNCH_DATA_ERRNO == launch_data_get_type(reply))
 214                 {
 215                 if (launch_data_get_errno(reply) == EACCES) { launch_data_free(msg); launch_data_free(reply); return(MACH_PORT_NULL); }
 216                 helplog(ASL_LEVEL_ERR, "Launchd checkin failed: %s.", strerror(launch_data_get_errno(reply))); goto fin;
 217                 }
 218         if (NULL == (datum = launch_data_dict_lookup(reply, LAUNCH_JOBKEY_MACHSERVICES)) || LAUNCH_DATA_DICTIONARY != launch_data_get_type(datum))
 219                 { helplog(ASL_LEVEL_ERR, "Launchd reply does not contain %s dictionary.", LAUNCH_JOBKEY_MACHSERVICES); goto fin; }
 220         if (NULL == (datum = launch_data_dict_lookup(datum, service_name)) || LAUNCH_DATA_MACHPORT != launch_data_get_type(datum))
 221                 { helplog(ASL_LEVEL_ERR, "Launchd reply does not contain %s Mach port.", service_name); goto fin; }
 222         if (MACH_PORT_NULL == (port = launch_data_get_machport(datum)))
 223                 { helplog(ASL_LEVEL_ERR, "Launchd gave me a null Mach port."); goto fin; }
 224         if (KERN_SUCCESS != (kr = mach_port_insert_right(mach_task_self(), port, port, MACH_MSG_TYPE_MAKE_SEND)))
 225                 { helplog(ASL_LEVEL_ERR, "mach_port_insert_right: %s", mach_error_string(kr)); goto fin; }
 226
 227 fin:
 228         if (NULL != msg)   launch_data_free(msg);
 229         if (NULL != reply) launch_data_free(reply);
 230         if (MACH_PORT_NULL == port) exit(EXIT_FAILURE);
 231         return port;
 232         }
 233
 234 static mach_port_t register_service(const char *service_name)
 235         {
 236         mach_port_t port = MACH_PORT_NULL;
 237         kern_return_t kr;
 238
 239         if (KERN_SUCCESS == (kr = bootstrap_check_in(bootstrap_port, (char *)service_name, &port)))
 240                 {
 241                 if (KERN_SUCCESS != (kr = mach_port_insert_right(mach_task_self(), port, port, MACH_MSG_TYPE_MAKE_SEND)))
 242                         helplog(ASL_LEVEL_ERR, "mach_port_insert_right: %s", mach_error_string(kr));
 243                 else
 244                         return port;
 245                 }
 246         if (KERN_SUCCESS != (kr = mach_port_allocate(mach_task_self(), MACH_PORT_RIGHT_RECEIVE, &port)))
 247                 { helplog(ASL_LEVEL_ERR, "mach_port_allocate: %s", mach_error_string(kr)); goto error; }
 248         if (KERN_SUCCESS != (kr = mach_port_insert_right(mach_task_self(), port, port, MACH_MSG_TYPE_MAKE_SEND)))
 249                 { helplog(ASL_LEVEL_ERR, "mach_port_insert_right: %s", mach_error_string(kr)); goto error; }
 250         // XXX bootstrap_register does not modify its second argument, but the prototype does not include const.
 251         if (KERN_SUCCESS != (kr = bootstrap_register(bootstrap_port, (char *)service_name, port)))
 252                 { helplog(ASL_LEVEL_ERR, "bootstrap_register failed: %s", mach_error_string(kr)); goto error; }
 253         return port;
 254 error:
 255         if (MACH_PORT_NULL != port) mach_port_deallocate(mach_task_self(), port);
 256         return MACH_PORT_NULL;
 257         }
 258
 259 int main(int ac, char *av[])
 260         {
 261         char *p = NULL;
 262         kern_return_t kr = KERN_FAILURE;
 263         mach_port_t port = MACH_PORT_NULL;
 264         long n;
 265         int ch;
 266
 267         while ((ch = getopt(ac, av, "dt:")) != -1)
 268                 switch (ch)
 269                 {
 270                 case 'd': opt_debug = 1; break;
 271                 case 't':
 272                         n = strtol(optarg, &p, 0);
 273                         if ('\0' == optarg[0] || '\0' != *p || n > LONG_MAX || n < 0)
 274                                 { fprintf(stderr, "Invalid idle timeout: %s\n", optarg); exit(EXIT_FAILURE); }
 275                         maxidle = n;
 276                         break;
 277                 case '?':
 278                 default:
 279                         fprintf(stderr, "Usage: mDNSResponderHelper [-d] [-t maxidle]\n");
 280                         exit(EXIT_FAILURE);
 281                 }
 282         ac -= optind;
 283         av += optind;
 284
 285         initialize_logging();
 286         helplog(ASL_LEVEL_INFO, "Starting");
 287         initialize_id();
 288
 289 #ifndef NO_SECURITYFRAMEWORK
 290         // We should normally be running as a system daemon.  However, that might not be the case in some scenarios (e.g. debugging).
 291         // Explicitly ensure that our Keychain operations utilize the system domain.
 292         SecKeychainSetPreferenceDomain(kSecPreferencesDomainSystem);
 293 #endif
 294         if (!opt_debug)
 295                 {
 296                 port = checkin(kmDNSHelperServiceName);
 297                 if (!port) helplog(ASL_LEVEL_ERR, "Launchd provided no launchdata; will open Mach port explicitly");
 298                 }
 299         if (!port) port = register_service(kmDNSHelperServiceName);
 300
 301         if (maxidle) actualidle = maxidle;
 302         initialize_timer(port);
 303
 304         kr = mach_msg_server(helper_server, MAX_MSG_SIZE, port,
 305                 MACH_RCV_TRAILER_ELEMENTS(MACH_RCV_TRAILER_AUDIT) | MACH_RCV_TRAILER_TYPE(MACH_MSG_TRAILER_FORMAT_0));
 306         if (KERN_SUCCESS != kr)
 307                 { helplog(ASL_LEVEL_ERR, "mach_msg_server: %s\n", mach_error_string(kr)); exit(EXIT_FAILURE); }
 308         exit(EXIT_SUCCESS);
 309         }
 310
 311 // Note: The C preprocessor stringify operator ('#') makes a string from its argument, without macro expansion
 312 // e.g. If "version" is #define'd to be "4", then STRINGIFY_AWE(version) will return the string "version", not "4"
 313 // To expand "version" to its value before making the string, use STRINGIFY(version) instead
 314 #define STRINGIFY_ARGUMENT_WITHOUT_EXPANSION(s) #s
 315 #define STRINGIFY(s) STRINGIFY_ARGUMENT_WITHOUT_EXPANSION(s)
 316
 317 // For convenience when using the "strings" command, this is the last thing in the file
 318 // The "@(#) " pattern is a special prefix the "what" command looks for
 319 const char VersionString_SCCS[] = "@(#) mDNSResponderHelper " STRINGIFY(mDNSResponderVersion) " (" __DATE__ " " __TIME__ ")";
 320
 321 // If the process crashes, then this string will be magically included in the automatically-generated crash log
 322 const char *__crashreporter_info__ = VersionString_SCCS + 5;
 323 asm(".desc ___crashreporter_info__, 0x10");