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#ifndef MDNS_USERNAME
53#define MDNS_USERNAME "nobody"
54#endif
55
56#ifdef __ANDROID__
57#include <cutils/sockets.h>
58#endif
59
60#define CONFIG_FILE "/etc/mdnsd.conf"
61static domainname DynDNSZone;                // Default wide-area zone for service registration
62static domainname DynDNSHostname;
63
64#define RR_CACHE_SIZE 500
65static CacheEntity gRRCache[RR_CACHE_SIZE];
66static mDNS_PlatformSupport PlatformStorage;
67
68mDNSlocal void mDNS_StatusCallback(mDNS *const m, mStatus result)
69	{
70	(void)m; // Unused
71	if (result == mStatus_NoError)
72		{
73		// On successful registration of dot-local mDNS host name, daemon may want to check if
74		// any name conflict and automatic renaming took place, and if so, record the newly negotiated
75		// name in persistent storage for next time. It should also inform the user of the name change.
76		// On Mac OS X we store the current dot-local mDNS host name in the SCPreferences store,
77		// and notify the user with a CFUserNotification.
78		}
79	else if (result == mStatus_ConfigChanged)
80		{
81		udsserver_handle_configchange(m);
82		}
83	else if (result == mStatus_GrowCache)
84		{
85		// Allocate another chunk of cache storage
86		CacheEntity *storage = malloc(sizeof(CacheEntity) * RR_CACHE_SIZE);
87		if (storage) mDNS_GrowCache(m, storage, RR_CACHE_SIZE);
88		}
89	}
90
91// %%% Reconfigure() probably belongs in the platform support layer (mDNSPosix.c), not the daemon cde
92// -- all client layers running on top of mDNSPosix.c need to handle network configuration changes,
93// not only the Unix Domain Socket Daemon
94
95static void Reconfigure(mDNS *m)
96	{
97	mDNSAddr DynDNSIP;
98	const mDNSAddr dummy = { mDNSAddrType_IPv4, { { { 1, 1, 1, 1 } } } };;
99	mDNS_SetPrimaryInterfaceInfo(m, NULL, NULL, NULL);
100	if (ParseDNSServers(m, uDNS_SERVERS_FILE) < 0)
101		LogMsg("Unable to parse DNS server list. Unicast DNS-SD unavailable");
102	ReadDDNSSettingsFromConfFile(m, CONFIG_FILE, &DynDNSHostname, &DynDNSZone, NULL);
103	mDNSPlatformSourceAddrForDest(&DynDNSIP, &dummy);
104	if (DynDNSHostname.c[0]) mDNS_AddDynDNSHostName(m, &DynDNSHostname, NULL, NULL);
105	if (DynDNSIP.type)       mDNS_SetPrimaryInterfaceInfo(m, &DynDNSIP, NULL, NULL);
106	mDNS_ConfigChanged(m);
107	}
108
109// Do appropriate things at startup with command line arguments. Calls exit() if unhappy.
110mDNSlocal void ParseCmdLinArgs(int argc, char **argv)
111	{
112	if (argc > 1)
113		{
114		if (0 == strcmp(argv[1], "-debug")) mDNS_DebugMode = mDNStrue;
115		else printf("Usage: %s [-debug]\n", argv[0]);
116		}
117#ifndef __ANDROID__
118	if (!mDNS_DebugMode)
119		{
120		int result = daemon(0, 0);
121		if (result != 0) { LogMsg("Could not run as daemon - exiting"); exit(result); }
122#if __APPLE__
123		LogMsg("The POSIX mdnsd should only be used on OS X for testing - exiting");
124		exit(-1);
125#endif
126		}
127#endif // !__ANDROID__
128	}
129
130mDNSlocal void DumpStateLog(mDNS *const m)
131// Dump a little log of what we've been up to.
132	{
133	LogMsg("---- BEGIN STATE LOG ----");
134	udsserver_info(m);
135	LogMsg("----  END STATE LOG  ----");
136	}
137
138mDNSlocal mStatus MainLoop(mDNS *m) // Loop until we quit.
139	{
140	sigset_t	signals;
141	mDNSBool	gotData = mDNSfalse;
142
143	mDNSPosixListenForSignalInEventLoop(SIGINT);
144	mDNSPosixListenForSignalInEventLoop(SIGTERM);
145	mDNSPosixListenForSignalInEventLoop(SIGUSR1);
146	mDNSPosixListenForSignalInEventLoop(SIGPIPE);
147	mDNSPosixListenForSignalInEventLoop(SIGHUP) ;
148
149	for (; ;)
150		{
151		// Work out how long we expect to sleep before the next scheduled task
152		struct timeval	timeout;
153		mDNSs32			ticks;
154
155		// Only idle if we didn't find any data the last time around
156		if (!gotData)
157			{
158			mDNSs32			nextTimerEvent = mDNS_Execute(m);
159			nextTimerEvent = udsserver_idle(nextTimerEvent);
160			ticks = nextTimerEvent - mDNS_TimeNow(m);
161			if (ticks < 1) ticks = 1;
162			}
163		else	// otherwise call EventLoop again with 0 timemout
164			ticks = 0;
165
166		timeout.tv_sec = ticks / mDNSPlatformOneSecond;
167		timeout.tv_usec = (ticks % mDNSPlatformOneSecond) * 1000000 / mDNSPlatformOneSecond;
168
169		(void) mDNSPosixRunEventLoopOnce(m, &timeout, &signals, &gotData);
170
171		if (sigismember(&signals, SIGHUP )) Reconfigure(m);
172		if (sigismember(&signals, SIGUSR1)) DumpStateLog(m);
173		// SIGPIPE happens when we try to write to a dead client; death should be detected soon in request_callback() and cleaned up.
174		if (sigismember(&signals, SIGPIPE)) LogMsg("Received SIGPIPE - ignoring");
175		if (sigismember(&signals, SIGINT) || sigismember(&signals, SIGTERM)) break;
176		}
177	return EINTR;
178	}
179
180int main(int argc, char **argv)
181	{
182	mStatus					err;
183
184	ParseCmdLinArgs(argc, argv);
185
186	LogMsg("%s starting", mDNSResponderVersionString);
187
188	err = mDNS_Init(&mDNSStorage, &PlatformStorage, gRRCache, RR_CACHE_SIZE, mDNS_Init_AdvertiseLocalAddresses,
189					mDNS_StatusCallback, mDNS_Init_NoInitCallbackContext);
190
191	if (mStatus_NoError == err)
192#ifdef __ANDROID__
193		{
194		dnssd_sock_t s[1];
195		char *socketname = strrchr(MDNS_UDS_SERVERPATH, '/');
196		if (socketname)
197			{
198			socketname++; // skip '/'
199			s[0] = android_get_control_socket(socketname);
200			err = udsserver_init(s, 1);
201			} else {
202			err = udsserver_init(mDNSNULL, 0);
203			}
204		}
205#else
206		err = udsserver_init(mDNSNULL, 0);
207#endif // __ANDROID__
208
209	Reconfigure(&mDNSStorage);
210
211	// Now that we're finished with anything privileged, switch over to running as "nobody"
212	if (mStatus_NoError == err)
213		{
214		const struct passwd *pw = getpwnam(MDNS_USERNAME);
215		if (pw != NULL)
216			setuid(pw->pw_uid);
217		else
218			LogMsg("WARNING: mdnsd continuing as root because user \"%s\" does not exist", MDNS_USERNAME);
219		}
220
221	if (mStatus_NoError == err)
222		err = MainLoop(&mDNSStorage);
223
224	LogMsg("%s stopping", mDNSResponderVersionString);
225
226	mDNS_Close(&mDNSStorage);
227
228	if (udsserver_exit() < 0)
229		LogMsg("ExitCallback: udsserver_exit failed");
230
231 #if MDNS_DEBUGMSGS > 0
232	printf("mDNSResponder exiting normally with %ld\n", err);
233 #endif
234
235	return err;
236	}
237
238//		uds_daemon support		////////////////////////////////////////////////////////////
239
240mStatus udsSupportAddFDToEventLoop(int fd, udsEventCallback callback, void *context, void **platform_data)
241/* Support routine for uds_daemon.c */
242	{
243	// Depends on the fact that udsEventCallback == mDNSPosixEventCallback
244	(void) platform_data;
245	return mDNSPosixAddFDToEventLoop(fd, callback, context);
246	}
247
248int udsSupportReadFD(dnssd_sock_t fd, char *buf, int len, int flags, void *platform_data)
249	{
250	(void) platform_data;
251	return recv(fd, buf, len, flags);
252	}
253
254mStatus udsSupportRemoveFDFromEventLoop(int fd, void *platform_data)		// Note: This also CLOSES the file descriptor
255	{
256	mStatus err = mDNSPosixRemoveFDFromEventLoop(fd);
257	(void) platform_data;
258	close(fd);
259	return err;
260	}
261
262mDNSexport void RecordUpdatedNiceLabel(mDNS *const m, mDNSs32 delay)
263	{
264	(void)m;
265	(void)delay;
266	// No-op, for now
267	}
268
269#if _BUILDING_XCODE_PROJECT_
270// If the process crashes, then this string will be magically included in the automatically-generated crash log
271const char *__crashreporter_info__ = mDNSResponderVersionString_SCCS + 5;
272asm(".desc ___crashreporter_info__, 0x10");
273#endif
274
275// For convenience when using the "strings" command, this is the last thing in the file
276#if mDNSResponderVersion > 1
277mDNSexport const char mDNSResponderVersionString_SCCS[] = "@(#) mDNSResponder-" STRINGIFY(mDNSResponderVersion) " (" __DATE__ " " __TIME__ ")";
278#elif MDNS_VERSIONSTR_NODTS
279mDNSexport const char mDNSResponderVersionString_SCCS[] = "@(#) mDNSResponder (Engineering Build)";
280#else
281mDNSexport const char mDNSResponderVersionString_SCCS[] = "@(#) mDNSResponder (Engineering Build) (" __DATE__ " " __TIME__ ")";
282#endif
283