mDNSPosix/PosixDaemon.c - platform/external/mdnsresponder - Git at Google

 /* -*- Mode: C; tab-width: 4 -*-
  *
  * Copyright (c) 2003-2004 Apple Computer, Inc. All rights reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *     http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.

 	File:		daemon.c

 	Contains:	main & associated Application layer for mDNSResponder on Linux.

  */

 #if __APPLE__
 // In Mac OS X 10.5 and later trying to use the daemon function gives a “‘daemon’ is deprecated”
 // error, which prevents compilation because we build with "-Werror".
 // Since this is supposed to be portable cross-platform code, we don't care that daemon is
 // deprecated on Mac OS X 10.5, so we use this preprocessor trick to eliminate the error message.
 #define daemon yes_we_know_that_daemon_is_deprecated_in_os_x_10_5_thankyou
 #endif

 #include <stdio.h>
 #include <string.h>
 #include <unistd.h>
 #include <stdlib.h>
 #include <signal.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <pwd.h>
 #include <sys/types.h>

 #ifdef __ANDROID__
 #include "cutils/sockets.h"
 #endif

 #if __APPLE__
 #undef daemon
 extern int daemon(int, int);
 #endif

 #include "mDNSEmbeddedAPI.h"
 #include "mDNSPosix.h"
 #include "mDNSUNP.h"		// For daemon()
 #include "uds_daemon.h"
 #include "PlatformCommon.h"

 #ifndef MDNS_USERNAME
 #define MDNS_USERNAME "nobody"
 #endif

 #define CONFIG_FILE "/etc/mdnsd.conf"
 static domainname DynDNSZone;                // Default wide-area zone for service registration
 static domainname DynDNSHostname;

 #define RR_CACHE_SIZE 500
 static CacheEntity gRRCache[RR_CACHE_SIZE];
 static mDNS_PlatformSupport PlatformStorage;

 mDNSlocal void mDNS_StatusCallback(mDNS *const m, mStatus result)
 	{
 	(void)m; // Unused
 	if (result == mStatus_NoError)
 		{
 		// On successful registration of dot-local mDNS host name, daemon may want to check if
 		// any name conflict and automatic renaming took place, and if so, record the newly negotiated
 		// name in persistent storage for next time. It should also inform the user of the name change.
 		// On Mac OS X we store the current dot-local mDNS host name in the SCPreferences store,
 		// and notify the user with a CFUserNotification.
 		}
 	else if (result == mStatus_ConfigChanged)
 		{
 		udsserver_handle_configchange(m);
 		}
 	else if (result == mStatus_GrowCache)
 		{
 		// Allocate another chunk of cache storage
 		CacheEntity *storage = malloc(sizeof(CacheEntity) * RR_CACHE_SIZE);
 		if (storage) mDNS_GrowCache(m, storage, RR_CACHE_SIZE);
 		}
 	}

 // %%% Reconfigure() probably belongs in the platform support layer (mDNSPosix.c), not the daemon cde
 // -- all client layers running on top of mDNSPosix.c need to handle network configuration changes,
 // not only the Unix Domain Socket Daemon

 static void Reconfigure(mDNS *m)
 	{
 	mDNSAddr DynDNSIP;
 	const mDNSAddr dummy = { mDNSAddrType_IPv4, { { { 1, 1, 1, 1 } } } };;
 	mDNS_SetPrimaryInterfaceInfo(m, NULL, NULL, NULL);
 	if (ParseDNSServers(m, uDNS_SERVERS_FILE) < 0)
 		LogMsg("Unable to parse DNS server list. Unicast DNS-SD unavailable");
 	ReadDDNSSettingsFromConfFile(m, CONFIG_FILE, &DynDNSHostname, &DynDNSZone, NULL);
 	mDNSPlatformSourceAddrForDest(&DynDNSIP, &dummy);
 	if (DynDNSHostname.c[0]) mDNS_AddDynDNSHostName(m, &DynDNSHostname, NULL, NULL);
 	if (DynDNSIP.type)       mDNS_SetPrimaryInterfaceInfo(m, &DynDNSIP, NULL, NULL);
 	mDNS_ConfigChanged(m);
 	}

 // Do appropriate things at startup with command line arguments. Calls exit() if unhappy.
 mDNSlocal void ParseCmdLinArgs(int argc, char **argv)
 	{
 	if (argc > 1)
 		{
 		if (0 == strcmp(argv[1], "-debug")) mDNS_DebugMode = mDNStrue;
 		else printf("Usage: %s [-debug]\n", argv[0]);
 		}
 #ifndef __ANDROID__
 	if (!mDNS_DebugMode)
 		{
 		int result = daemon(0, 0);
 		if (result != 0) { LogMsg("Could not run as daemon - exiting"); exit(result); }
 #if __APPLE__
 		LogMsg("The POSIX mdnsd should only be used on OS X for testing - exiting");
 		exit(-1);
 #endif
 		}
 #endif // !__ANDROID__
 	}

 mDNSlocal void DumpStateLog(mDNS *const m)
 // Dump a little log of what we've been up to.
 	{
 	LogMsg("---- BEGIN STATE LOG ----");
 	udsserver_info(m);
 	LogMsg("----  END STATE LOG  ----");
 	}

 mDNSlocal mStatus MainLoop(mDNS *m) // Loop until we quit.
 	{
 	sigset_t	signals;
 	mDNSBool	gotData = mDNSfalse;

 	mDNSPosixListenForSignalInEventLoop(SIGINT);
 	mDNSPosixListenForSignalInEventLoop(SIGTERM);
 	mDNSPosixListenForSignalInEventLoop(SIGUSR1);
 	mDNSPosixListenForSignalInEventLoop(SIGPIPE);
 	mDNSPosixListenForSignalInEventLoop(SIGHUP) ;

 	for (; ;)
 		{
 		// Work out how long we expect to sleep before the next scheduled task
 		struct timeval	timeout;
 		mDNSs32			ticks;

 		// Only idle if we didn't find any data the last time around
 		if (!gotData)
 			{
 			mDNSs32			nextTimerEvent = mDNS_Execute(m);
 			nextTimerEvent = udsserver_idle(nextTimerEvent);
 			ticks = nextTimerEvent - mDNS_TimeNow(m);
 			if (ticks < 1) ticks = 1;
 			}
 		else	// otherwise call EventLoop again with 0 timemout
 			ticks = 0;

 		timeout.tv_sec = ticks / mDNSPlatformOneSecond;
 		timeout.tv_usec = (ticks % mDNSPlatformOneSecond) * 1000000 / mDNSPlatformOneSecond;

 		(void) mDNSPosixRunEventLoopOnce(m, &timeout, &signals, &gotData);

 		if (sigismember(&signals, SIGHUP )) Reconfigure(m);
 		if (sigismember(&signals, SIGUSR1)) DumpStateLog(m);
 		// SIGPIPE happens when we try to write to a dead client; death should be detected soon in request_callback() and cleaned up.
 		if (sigismember(&signals, SIGPIPE)) LogMsg("Received SIGPIPE - ignoring");
 		if (sigismember(&signals, SIGINT) || sigismember(&signals, SIGTERM)) break;
 		}
 	return EINTR;
 	}

 int main(int argc, char **argv)
 	{
 	mStatus					err;

 	ParseCmdLinArgs(argc, argv);

 	LogMsg("%s starting", mDNSResponderVersionString);

 	err = mDNS_Init(&mDNSStorage, &PlatformStorage, gRRCache, RR_CACHE_SIZE, mDNS_Init_AdvertiseLocalAddresses,
 					mDNS_StatusCallback, mDNS_Init_NoInitCallbackContext);

 	if (mStatus_NoError == err)
 #ifdef __ANDROID__
 		{
 		dnssd_sock_t s[1];
 		char *socketname = strrchr(MDNS_UDS_SERVERPATH, '/');
 		if (socketname)
 			{
 			socketname++; // skip '/'
 			s[0] = android_get_control_socket(socketname);
 			err = udsserver_init(s, 1);
 			} else {
 			err = udsserver_init(mDNSNULL, 0);
 			}
 		}
 #else
 		err = udsserver_init(mDNSNULL, 0);
 #endif // __ANDROID__

 	Reconfigure(&mDNSStorage);

 	// Now that we're finished with anything privileged, switch over to running as "nobody"
 	if (mStatus_NoError == err)
 		{
 		const struct passwd *pw = getpwnam(MDNS_USERNAME);
 		if (pw != NULL)
 			setuid(pw->pw_uid);
 		else
 			LogMsg("WARNING: mdnsd continuing as root because user \"%s\" does not exist", MDNS_USERNAME);
 		}

 	if (mStatus_NoError == err)
 		err = MainLoop(&mDNSStorage);

 	LogMsg("%s stopping", mDNSResponderVersionString);

 	mDNS_Close(&mDNSStorage);

 	if (udsserver_exit() < 0)
 		LogMsg("ExitCallback: udsserver_exit failed");

  #if MDNS_DEBUGMSGS > 0
 	printf("mDNSResponder exiting normally with %ld\n", err);
  #endif

 	return err;
 	}

 //		uds_daemon support		////////////////////////////////////////////////////////////

 mStatus udsSupportAddFDToEventLoop(int fd, udsEventCallback callback, void *context, void **platform_data)
 /* Support routine for uds_daemon.c */
 	{
 	// Depends on the fact that udsEventCallback == mDNSPosixEventCallback
 	(void) platform_data;
 	return mDNSPosixAddFDToEventLoop(fd, callback, context);
 	}

 int udsSupportReadFD(dnssd_sock_t fd, char *buf, int len, int flags, void *platform_data)
 	{
 	(void) platform_data;
 	return recv(fd, buf, len, flags);
 	}

 mStatus udsSupportRemoveFDFromEventLoop(int fd, void *platform_data)		// Note: This also CLOSES the file descriptor
 	{
 	mStatus err = mDNSPosixRemoveFDFromEventLoop(fd);
 	(void) platform_data;
 	close(fd);
 	return err;
 	}

 mDNSexport void RecordUpdatedNiceLabel(mDNS *const m, mDNSs32 delay)
 	{
 	(void)m;
 	(void)delay;
 	// No-op, for now
 	}

 #if _BUILDING_XCODE_PROJECT_
 // If the process crashes, then this string will be magically included in the automatically-generated crash log
 const char *__crashreporter_info__ = mDNSResponderVersionString_SCCS + 5;
 asm(".desc ___crashreporter_info__, 0x10");
 #endif

 // For convenience when using the "strings" command, this is the last thing in the file
 #if mDNSResponderVersion > 1
 mDNSexport const char mDNSResponderVersionString_SCCS[] = "@(#) mDNSResponder-" STRINGIFY(mDNSResponderVersion) " (" __DATE__ " " __TIME__ ")";
 #elif MDNS_VERSIONSTR_NODTS
 mDNSexport const char mDNSResponderVersionString_SCCS[] = "@(#) mDNSResponder (Engineering Build)";
 #else
 mDNSexport const char mDNSResponderVersionString_SCCS[] = "@(#) mDNSResponder (Engineering Build) (" __DATE__ " " __TIME__ ")";
 #endif
	/* -- Mode: C; tab-width: 4 --
	*
	* Copyright (c) 2003-2004 Apple Computer, Inc. All rights reserved.
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.

	File: daemon.c

	Contains: main & associated Application layer for mDNSResponder on Linux.

	*/

	#if __APPLE__
	// In Mac OS X 10.5 and later trying to use the daemon function gives a “‘daemon’ is deprecated”
	// error, which prevents compilation because we build with "-Werror".
	// Since this is supposed to be portable cross-platform code, we don't care that daemon is
	// deprecated on Mac OS X 10.5, so we use this preprocessor trick to eliminate the error message.
	#define daemon yes_we_know_that_daemon_is_deprecated_in_os_x_10_5_thankyou
	#endif

	#include <stdio.h>
	#include <string.h>
	#include <unistd.h>
	#include <stdlib.h>
	#include <signal.h>
	#include <errno.h>
	#include <fcntl.h>
	#include <pwd.h>
	#include <sys/types.h>

	#ifdef __ANDROID__
	#include "cutils/sockets.h"
	#endif

	#if __APPLE__
	#undef daemon
	extern int daemon(int, int);
	#endif

	#include "mDNSEmbeddedAPI.h"
	#include "mDNSPosix.h"
	#include "mDNSUNP.h" // For daemon()
	#include "uds_daemon.h"
	#include "PlatformCommon.h"

	#ifndef MDNS_USERNAME
	#define MDNS_USERNAME "nobody"
	#endif

	#define CONFIG_FILE "/etc/mdnsd.conf"
	static domainname DynDNSZone; // Default wide-area zone for service registration
	static domainname DynDNSHostname;

	#define RR_CACHE_SIZE 500
	static CacheEntity gRRCache[RR_CACHE_SIZE];
	static mDNS_PlatformSupport PlatformStorage;

	mDNSlocal void mDNS_StatusCallback(mDNS *const m, mStatus result)
	{
	(void)m; // Unused
	if (result == mStatus_NoError)
	{
	// On successful registration of dot-local mDNS host name, daemon may want to check if
	// any name conflict and automatic renaming took place, and if so, record the newly negotiated
	// name in persistent storage for next time. It should also inform the user of the name change.
	// On Mac OS X we store the current dot-local mDNS host name in the SCPreferences store,
	// and notify the user with a CFUserNotification.
	}
	else if (result == mStatus_ConfigChanged)
	{
	udsserver_handle_configchange(m);
	}
	else if (result == mStatus_GrowCache)
	{
	// Allocate another chunk of cache storage
	CacheEntity storage = malloc(sizeof(CacheEntity) RR_CACHE_SIZE);
	if (storage) mDNS_GrowCache(m, storage, RR_CACHE_SIZE);
	}
	}

	// %%% Reconfigure() probably belongs in the platform support layer (mDNSPosix.c), not the daemon cde
	// -- all client layers running on top of mDNSPosix.c need to handle network configuration changes,
	// not only the Unix Domain Socket Daemon

	static void Reconfigure(mDNS *m)
	{
	mDNSAddr DynDNSIP;
	const mDNSAddr dummy = { mDNSAddrType_IPv4, { { { 1, 1, 1, 1 } } } };;
	mDNS_SetPrimaryInterfaceInfo(m, NULL, NULL, NULL);
	if (ParseDNSServers(m, uDNS_SERVERS_FILE) < 0)
	LogMsg("Unable to parse DNS server list. Unicast DNS-SD unavailable");
	ReadDDNSSettingsFromConfFile(m, CONFIG_FILE, &DynDNSHostname, &DynDNSZone, NULL);
	mDNSPlatformSourceAddrForDest(&DynDNSIP, &dummy);
	if (DynDNSHostname.c[0]) mDNS_AddDynDNSHostName(m, &DynDNSHostname, NULL, NULL);
	if (DynDNSIP.type) mDNS_SetPrimaryInterfaceInfo(m, &DynDNSIP, NULL, NULL);
	mDNS_ConfigChanged(m);
	}

	// Do appropriate things at startup with command line arguments. Calls exit() if unhappy.
	mDNSlocal void ParseCmdLinArgs(int argc, char **argv)
	{
	if (argc > 1)
	{
	if (0 == strcmp(argv[1], "-debug")) mDNS_DebugMode = mDNStrue;
	else printf("Usage: %s [-debug]\n", argv[0]);
	}
	#ifndef __ANDROID__
	if (!mDNS_DebugMode)
	{
	int result = daemon(0, 0);
	if (result != 0) { LogMsg("Could not run as daemon - exiting"); exit(result); }
	#if __APPLE__
	LogMsg("The POSIX mdnsd should only be used on OS X for testing - exiting");
	exit(-1);
	#endif
	}
	#endif // !__ANDROID__
	}

	mDNSlocal void DumpStateLog(mDNS *const m)
	// Dump a little log of what we've been up to.
	{
	LogMsg("---- BEGIN STATE LOG ----");
	udsserver_info(m);
	LogMsg("---- END STATE LOG ----");
	}

	mDNSlocal mStatus MainLoop(mDNS *m) // Loop until we quit.
	{
	sigset_t signals;
	mDNSBool gotData = mDNSfalse;

	mDNSPosixListenForSignalInEventLoop(SIGINT);
	mDNSPosixListenForSignalInEventLoop(SIGTERM);
	mDNSPosixListenForSignalInEventLoop(SIGUSR1);
	mDNSPosixListenForSignalInEventLoop(SIGPIPE);
	mDNSPosixListenForSignalInEventLoop(SIGHUP) ;

	for (; ;)
	{
	// Work out how long we expect to sleep before the next scheduled task
	struct timeval timeout;
	mDNSs32 ticks;

	// Only idle if we didn't find any data the last time around
	if (!gotData)
	{
	mDNSs32 nextTimerEvent = mDNS_Execute(m);
	nextTimerEvent = udsserver_idle(nextTimerEvent);
	ticks = nextTimerEvent - mDNS_TimeNow(m);
	if (ticks < 1) ticks = 1;
	}
	else // otherwise call EventLoop again with 0 timemout
	ticks = 0;

	timeout.tv_sec = ticks / mDNSPlatformOneSecond;
	timeout.tv_usec = (ticks % mDNSPlatformOneSecond) * 1000000 / mDNSPlatformOneSecond;

	(void) mDNSPosixRunEventLoopOnce(m, &timeout, &signals, &gotData);

	if (sigismember(&signals, SIGHUP )) Reconfigure(m);
	if (sigismember(&signals, SIGUSR1)) DumpStateLog(m);
	// SIGPIPE happens when we try to write to a dead client; death should be detected soon in request_callback() and cleaned up.
	if (sigismember(&signals, SIGPIPE)) LogMsg("Received SIGPIPE - ignoring");
	if (sigismember(&signals, SIGINT) \|\| sigismember(&signals, SIGTERM)) break;
	}
	return EINTR;
	}

	int main(int argc, char **argv)
	{
	mStatus err;

	ParseCmdLinArgs(argc, argv);

	LogMsg("%s starting", mDNSResponderVersionString);

	err = mDNS_Init(&mDNSStorage, &PlatformStorage, gRRCache, RR_CACHE_SIZE, mDNS_Init_AdvertiseLocalAddresses,
	mDNS_StatusCallback, mDNS_Init_NoInitCallbackContext);

	if (mStatus_NoError == err)
	#ifdef __ANDROID__
	{
	dnssd_sock_t s[1];
	char *socketname = strrchr(MDNS_UDS_SERVERPATH, '/');
	if (socketname)
	{
	socketname++; // skip '/'
	s[0] = android_get_control_socket(socketname);
	err = udsserver_init(s, 1);
	} else {
	err = udsserver_init(mDNSNULL, 0);
	}
	}
	#else
	err = udsserver_init(mDNSNULL, 0);
	#endif // __ANDROID__

	Reconfigure(&mDNSStorage);

	// Now that we're finished with anything privileged, switch over to running as "nobody"
	if (mStatus_NoError == err)
	{
	const struct passwd *pw = getpwnam(MDNS_USERNAME);
	if (pw != NULL)
	setuid(pw->pw_uid);
	else
	LogMsg("WARNING: mdnsd continuing as root because user \"%s\" does not exist", MDNS_USERNAME);
	}

	if (mStatus_NoError == err)
	err = MainLoop(&mDNSStorage);

	LogMsg("%s stopping", mDNSResponderVersionString);

	mDNS_Close(&mDNSStorage);

	if (udsserver_exit() < 0)
	LogMsg("ExitCallback: udsserver_exit failed");

	#if MDNS_DEBUGMSGS > 0
	printf("mDNSResponder exiting normally with %ld\n", err);
	#endif

	return err;
	}

	// uds_daemon support ////////////////////////////////////////////////////////////

	mStatus udsSupportAddFDToEventLoop(int fd, udsEventCallback callback, void context, void *platform_data)
	/* Support routine for uds_daemon.c */
	{
	// Depends on the fact that udsEventCallback == mDNSPosixEventCallback
	(void) platform_data;
	return mDNSPosixAddFDToEventLoop(fd, callback, context);
	}

	int udsSupportReadFD(dnssd_sock_t fd, char buf, int len, int flags, void platform_data)
	{
	(void) platform_data;
	return recv(fd, buf, len, flags);
	}

	mStatus udsSupportRemoveFDFromEventLoop(int fd, void *platform_data) // Note: This also CLOSES the file descriptor
	{
	mStatus err = mDNSPosixRemoveFDFromEventLoop(fd);
	(void) platform_data;
	close(fd);
	return err;
	}

	mDNSexport void RecordUpdatedNiceLabel(mDNS *const m, mDNSs32 delay)
	{
	(void)m;
	(void)delay;
	// No-op, for now
	}

	#if _BUILDING_XCODE_PROJECT_
	// If the process crashes, then this string will be magically included in the automatically-generated crash log
	const char *__crashreporter_info__ = mDNSResponderVersionString_SCCS + 5;
	asm(".desc ___crashreporter_info__, 0x10");
	#endif

	// For convenience when using the "strings" command, this is the last thing in the file
	#if mDNSResponderVersion > 1
	mDNSexport const char mDNSResponderVersionString_SCCS[] = "@(#) mDNSResponder-" STRINGIFY(mDNSResponderVersion) " (" __DATE__ " " __TIME__ ")";
	#elif MDNS_VERSIONSTR_NODTS
	mDNSexport const char mDNSResponderVersionString_SCCS[] = "@(#) mDNSResponder (Engineering Build)";
	#else
	mDNSexport const char mDNSResponderVersionString_SCCS[] = "@(#) mDNSResponder (Engineering Build) (" __DATE__ " " __TIME__ ")";
	#endif