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
43extern 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"
53static domainname DynDNSZone;                // Default wide-area zone for service registration
54static domainname DynDNSHostname;
55
56#define RR_CACHE_SIZE 500
57static CacheEntity gRRCache[RR_CACHE_SIZE];
58static mDNS_PlatformSupport PlatformStorage;
59
60mDNSlocal 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
87static 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.
102mDNSlocal 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
121mDNSlocal 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
129mDNSlocal 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
171int 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
216mStatus 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
224int 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
230mStatus 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
238mDNSexport 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
247const char *__crashreporter_info__ = mDNSResponderVersionString_SCCS + 5;
248asm (".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
253mDNSexport const char mDNSResponderVersionString_SCCS[] = "@(#) mDNSResponder-" STRINGIFY(mDNSResponderVersion) " (" __DATE__ " " __TIME__ ")";
254#elif MDNS_VERSIONSTR_NODTS
255mDNSexport const char mDNSResponderVersionString_SCCS[] = "@(#) mDNSResponder (Engineering Build)";
256#else
257mDNSexport const char mDNSResponderVersionString_SCCS[] = "@(#) mDNSResponder (Engineering Build) (" __DATE__ " " __TIME__ ")";
258#endif
259