mtpd.c - platform/external/mtpd - Git at Google

 /*
  * Copyright (C) 2009 The Android Open Source Project
  *
  * 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.
  */

 #include <stdio.h>
 #include <stdlib.h>
 #include <stdarg.h>
 #include <string.h>
 #include <errno.h>
 #include <sys/types.h>
 #include <sys/socket.h>
 #include <sys/poll.h>
 #include <sys/wait.h>
 #include <netdb.h>
 #include <signal.h>
 #include <unistd.h>
 #include <fcntl.h>
 #include <time.h>

 #ifdef ANDROID_CHANGES
 #include <android/log.h>
 #include <cutils/sockets.h>
 #include "keystore_get.h"
 #endif

 #include "mtpd.h"

 int the_socket = -1;

 extern struct protocol l2tp;
 extern struct protocol pptp;
 static struct protocol *protocols[] = {&l2tp, &pptp, NULL};
 static struct protocol *the_protocol;

 static int pppd_argc;
 static char **pppd_argv;
 static pid_t pppd_pid;

 /* We redirect signals to a pipe in order to prevent race conditions. */
 static int signals[2];

 static void interrupt(int signal)
 {
     write(signals[1], &signal, sizeof(int));
 }

 static int initialize(int argc, char **argv)
 {
     int timeout = 0;
     int i;

     for (i = 2; i < argc; ++i) {
         if (!argv[i][0]) {
             pppd_argc = argc - i - 1;
             pppd_argv = &argv[i + 1];
             argc = i;
             break;
         }
     }

     if (argc >= 2) {
         for (i = 0; protocols[i]; ++i) {
             if (!strcmp(argv[1], protocols[i]->name)) {
                 log_print(INFO, "Using protocol %s", protocols[i]->name);
                 the_protocol = protocols[i];
                 timeout = the_protocol->connect(argc - 2, &argv[2]);
                 break;
             }
         }
     }

     if (!the_protocol || timeout == -USAGE_ERROR) {
         printf("Usage: %s <protocol-args> '' <pppd-args>, "
                "where protocol-args are one of:\n", argv[0]);
         for (i = 0; protocols[i]; ++i) {
             printf("       %s %s\n", protocols[i]->name, protocols[i]->usage);
         }
         exit(USAGE_ERROR);
     }
     return timeout;
 }

 static void stop_pppd()
 {
     if (pppd_pid) {
         log_print(INFO, "Sending signal to pppd (pid = %d)", pppd_pid);
         kill(pppd_pid, SIGTERM);
         sleep(5);
         pppd_pid = 0;
     }
 }

 #ifdef ANDROID_CHANGES

 static int get_control_and_arguments(int *argc, char ***argv)
 {
     static char *args[256];
     int control;
     int i;

     if ((i = android_get_control_socket("mtpd")) == -1) {
         return -1;
     }
     log_print(DEBUG, "Waiting for control socket");
     if (listen(i, 1) == -1 || (control = accept(i, NULL, 0)) == -1) {
         log_print(FATAL, "Cannot get control socket");
         exit(SYSTEM_ERROR);
     }
     close(i);
     fcntl(control, F_SETFD, FD_CLOEXEC);

     args[0] = (*argv)[0];
     for (i = 1; i < 256; ++i) {
         unsigned char length;
         if (recv(control, &length, 1, 0) != 1) {
             log_print(FATAL, "Cannot get argument length");
             exit(SYSTEM_ERROR);
         }
         if (length == 0xFF) {
             break;
         } else {
             int offset = 0;
             args[i] = malloc(length + 1);
             while (offset < length) {
                 int n = recv(control, &args[i][offset], length - offset, 0);
                 if (n > 0) {
                     offset += n;
                 } else {
                     log_print(FATAL, "Cannot get argument value");
                     exit(SYSTEM_ERROR);
                 }
             }
             args[i][length] = 0;
         }
     }
     log_print(DEBUG, "Received %d arguments", i - 1);

     /* L2TP secret is the only thing stored in keystore. We do the query here
      * so other files are clean and free from android specific code. */
     if (i > 4 && !strcmp("l2tp", args[1]) && args[4][0]) {
         char *value = keystore_get(args[4], NULL);
         if (!value) {
             log_print(FATAL, "Cannot get L2TP secret from keystore");
             exit(SYSTEM_ERROR);
         }
         free(args[4]);
         args[4] = value;
     }

     *argc = i;
     *argv = args;
     return control;
 }

 #endif

 int main(int argc, char **argv)
 {
     struct pollfd pollfds[2];
     int timeout;
     int status;
 #ifdef ANDROID_CHANGES
     int control = get_control_and_arguments(&argc, &argv);
     unsigned char code = argc - 1;
     send(control, &code, 1, 0);
 #endif

     srandom(time(NULL));

     if (pipe(signals) == -1) {
         log_print(FATAL, "Pipe() %s", strerror(errno));
         exit(SYSTEM_ERROR);
     }
     fcntl(signals[0], F_SETFD, FD_CLOEXEC);
     fcntl(signals[1], F_SETFD, FD_CLOEXEC);

     timeout = initialize(argc, argv);

     signal(SIGHUP, interrupt);
     signal(SIGINT, interrupt);
     signal(SIGTERM, interrupt);
     signal(SIGCHLD, interrupt);
     signal(SIGPIPE, SIG_IGN);
     atexit(stop_pppd);

     pollfds[0].fd = signals[0];
     pollfds[0].events = POLLIN;
     pollfds[1].fd = the_socket;
     pollfds[1].events = POLLIN;

     while (timeout >= 0) {
         if (poll(pollfds, 2, timeout ? timeout : -1) == -1 && errno != EINTR) {
             log_print(FATAL, "Poll() %s", strerror(errno));
             exit(SYSTEM_ERROR);
         }
         if (pollfds[0].revents) {
             break;
         }
         timeout = pollfds[1].revents ?
             the_protocol->process() : the_protocol->timeout();
     }

     if (timeout < 0) {
         status = -timeout;
     } else {
         int signal;
         read(signals[0], &signal, sizeof(int));
         log_print(INFO, "Received signal %d", signal);
         if (signal == SIGCHLD && waitpid(pppd_pid, &status, WNOHANG) == pppd_pid
             && WIFEXITED(status)) {
             status = WEXITSTATUS(status);
             log_print(INFO, "Pppd is terminated (status = %d)", status);
             status += PPPD_EXITED;
             pppd_pid = 0;
         } else {
             status = USER_REQUESTED;
         }
     }

     stop_pppd();
     the_protocol->shutdown();

 #ifdef ANDROID_CHANGES
     code = status;
     send(control, &code, 1, 0);
 #endif
     log_print(INFO, "Mtpd is terminated (status = %d)", status);
     return status;
 }

 void log_print(int level, char *format, ...)
 {
     if (level >= 0 && level <= LOG_MAX) {
 #ifdef ANDROID_CHANGES
         static int levels[5] = {
             ANDROID_LOG_DEBUG, ANDROID_LOG_INFO, ANDROID_LOG_WARN,
             ANDROID_LOG_ERROR, ANDROID_LOG_FATAL
         };
         va_list ap;
         va_start(ap, format);
         __android_log_vprint(levels[level], "mtpd", format, ap);
         va_end(ap);
 #else
         static char *levels = "DIWEF";
         va_list ap;
         fprintf(stderr, "%c: ", levels[level]);
         va_start(ap, format);
         vfprintf(stderr, format, ap);
         va_end(ap);
         fputc('\n', stderr);
 #endif
     }
 }

 void create_socket(int family, int type, char *server, char *port)
 {
     struct addrinfo hints = {
         .ai_flags = AI_NUMERICSERV,
         .ai_family = family,
         .ai_socktype = type,
     };
     struct addrinfo *records;
     struct addrinfo *r;
     int error;

     log_print(INFO, "Connecting to %s port %s", server, port);

     error = getaddrinfo(server, port, &hints, &records);
     if (error) {
         log_print(FATAL, "Getaddrinfo() %s", (error == EAI_SYSTEM) ?
                   strerror(errno) : gai_strerror(error));
         exit(NETWORK_ERROR);
     }

     for (r = records; r; r = r->ai_next) {
         the_socket = socket(r->ai_family, r->ai_socktype, r->ai_protocol);
         if (the_socket != -1) {
             if (connect(the_socket, r->ai_addr, r->ai_addrlen) == 0) {
                 break;
             }
             close(the_socket);
             the_socket = -1;
         }
     }

     freeaddrinfo(records);

     if (the_socket == -1) {
         log_print(FATAL, "Connect() %s", strerror(errno));
         exit(NETWORK_ERROR);
     }

     fcntl(the_socket, F_SETFD, FD_CLOEXEC);
     log_print(INFO, "Connection established (socket = %d)", the_socket);
 }

 void start_pppd(int pppox)
 {
     if (pppd_pid) {
         log_print(WARNING, "Pppd is already started (pid = %d)", pppd_pid);
         close(pppox);
         return;
     }

     log_print(INFO, "Starting pppd (pppox = %d)", pppox);

     pppd_pid = fork();
     if (pppd_pid < 0) {
         log_print(FATAL, "Fork() %s", strerror(errno));
         exit(SYSTEM_ERROR);
     }

     if (!pppd_pid) {
         char *args[pppd_argc + 5];
         char number[12];

         sprintf(number, "%d", pppox);
         args[0] = "pppd";
         args[1] = "nodetach";
         args[2] = "pppox";
         args[3] = number;
         memcpy(&args[4], pppd_argv, sizeof(char *) * pppd_argc);
         args[4 + pppd_argc] = NULL;

         execvp("pppd", args);
         log_print(FATAL, "Exec() %s", strerror(errno));
         exit(1); /* Pretending a fatal error in pppd. */
     }

     log_print(INFO, "Pppd started (pid = %d)", pppd_pid);
     close(pppox);
 }
	/*
	* Copyright (C) 2009 The Android Open Source Project
	*
	* 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.
	*/

	#include <stdio.h>
	#include <stdlib.h>
	#include <stdarg.h>
	#include <string.h>
	#include <errno.h>
	#include <sys/types.h>
	#include <sys/socket.h>
	#include <sys/poll.h>
	#include <sys/wait.h>
	#include <netdb.h>
	#include <signal.h>
	#include <unistd.h>
	#include <fcntl.h>
	#include <time.h>

	#ifdef ANDROID_CHANGES
	#include <android/log.h>
	#include <cutils/sockets.h>
	#include "keystore_get.h"
	#endif

	#include "mtpd.h"

	int the_socket = -1;

	extern struct protocol l2tp;
	extern struct protocol pptp;
	static struct protocol *protocols[] = {&l2tp, &pptp, NULL};
	static struct protocol *the_protocol;

	static int pppd_argc;
	static char **pppd_argv;
	static pid_t pppd_pid;

	/* We redirect signals to a pipe in order to prevent race conditions. */
	static int signals[2];

	static void interrupt(int signal)
	{
	write(signals[1], &signal, sizeof(int));
	}

	static int initialize(int argc, char **argv)
	{
	int timeout = 0;
	int i;

	for (i = 2; i < argc; ++i) {
	if (!argv[i][0]) {
	pppd_argc = argc - i - 1;
	pppd_argv = &argv[i + 1];
	argc = i;
	break;
	}
	}

	if (argc >= 2) {
	for (i = 0; protocols[i]; ++i) {
	if (!strcmp(argv[1], protocols[i]->name)) {
	log_print(INFO, "Using protocol %s", protocols[i]->name);
	the_protocol = protocols[i];
	timeout = the_protocol->connect(argc - 2, &argv[2]);
	break;
	}
	}
	}

	if (!the_protocol \|\| timeout == -USAGE_ERROR) {
	printf("Usage: %s <protocol-args> '' <pppd-args>, "
	"where protocol-args are one of:\n", argv[0]);
	for (i = 0; protocols[i]; ++i) {
	printf(" %s %s\n", protocols[i]->name, protocols[i]->usage);
	}
	exit(USAGE_ERROR);
	}
	return timeout;
	}

	static void stop_pppd()
	{
	if (pppd_pid) {
	log_print(INFO, "Sending signal to pppd (pid = %d)", pppd_pid);
	kill(pppd_pid, SIGTERM);
	sleep(5);
	pppd_pid = 0;
	}
	}

	#ifdef ANDROID_CHANGES

	static int get_control_and_arguments(int argc, char **argv)
	{
	static char *args[256];
	int control;
	int i;

	if ((i = android_get_control_socket("mtpd")) == -1) {
	return -1;
	}
	log_print(DEBUG, "Waiting for control socket");
	if (listen(i, 1) == -1 \|\| (control = accept(i, NULL, 0)) == -1) {
	log_print(FATAL, "Cannot get control socket");
	exit(SYSTEM_ERROR);
	}
	close(i);
	fcntl(control, F_SETFD, FD_CLOEXEC);

	args[0] = (*argv)[0];
	for (i = 1; i < 256; ++i) {
	unsigned char length;
	if (recv(control, &length, 1, 0) != 1) {
	log_print(FATAL, "Cannot get argument length");
	exit(SYSTEM_ERROR);
	}
	if (length == 0xFF) {
	break;
	} else {
	int offset = 0;
	args[i] = malloc(length + 1);
	while (offset < length) {
	int n = recv(control, &args[i][offset], length - offset, 0);
	if (n > 0) {
	offset += n;
	} else {
	log_print(FATAL, "Cannot get argument value");
	exit(SYSTEM_ERROR);
	}
	}
	args[i][length] = 0;
	}
	}
	log_print(DEBUG, "Received %d arguments", i - 1);

	/* L2TP secret is the only thing stored in keystore. We do the query here
	* so other files are clean and free from android specific code. */
	if (i > 4 && !strcmp("l2tp", args[1]) && args[4][0]) {
	char *value = keystore_get(args[4], NULL);
	if (!value) {
	log_print(FATAL, "Cannot get L2TP secret from keystore");
	exit(SYSTEM_ERROR);
	}
	free(args[4]);
	args[4] = value;
	}

	*argc = i;
	*argv = args;
	return control;
	}

	#endif

	int main(int argc, char **argv)
	{
	struct pollfd pollfds[2];
	int timeout;
	int status;
	#ifdef ANDROID_CHANGES
	int control = get_control_and_arguments(&argc, &argv);
	unsigned char code = argc - 1;
	send(control, &code, 1, 0);
	#endif

	srandom(time(NULL));

	if (pipe(signals) == -1) {
	log_print(FATAL, "Pipe() %s", strerror(errno));
	exit(SYSTEM_ERROR);
	}
	fcntl(signals[0], F_SETFD, FD_CLOEXEC);
	fcntl(signals[1], F_SETFD, FD_CLOEXEC);

	timeout = initialize(argc, argv);

	signal(SIGHUP, interrupt);
	signal(SIGINT, interrupt);
	signal(SIGTERM, interrupt);
	signal(SIGCHLD, interrupt);
	signal(SIGPIPE, SIG_IGN);
	atexit(stop_pppd);

	pollfds[0].fd = signals[0];
	pollfds[0].events = POLLIN;
	pollfds[1].fd = the_socket;
	pollfds[1].events = POLLIN;

	while (timeout >= 0) {
	if (poll(pollfds, 2, timeout ? timeout : -1) == -1 && errno != EINTR) {
	log_print(FATAL, "Poll() %s", strerror(errno));
	exit(SYSTEM_ERROR);
	}
	if (pollfds[0].revents) {
	break;
	}
	timeout = pollfds[1].revents ?
	the_protocol->process() : the_protocol->timeout();
	}

	if (timeout < 0) {
	status = -timeout;
	} else {
	int signal;
	read(signals[0], &signal, sizeof(int));
	log_print(INFO, "Received signal %d", signal);
	if (signal == SIGCHLD && waitpid(pppd_pid, &status, WNOHANG) == pppd_pid
	&& WIFEXITED(status)) {
	status = WEXITSTATUS(status);
	log_print(INFO, "Pppd is terminated (status = %d)", status);
	status += PPPD_EXITED;
	pppd_pid = 0;
	} else {
	status = USER_REQUESTED;
	}
	}

	stop_pppd();
	the_protocol->shutdown();

	#ifdef ANDROID_CHANGES
	code = status;
	send(control, &code, 1, 0);
	#endif
	log_print(INFO, "Mtpd is terminated (status = %d)", status);
	return status;
	}

	void log_print(int level, char *format, ...)
	{
	if (level >= 0 && level <= LOG_MAX) {
	#ifdef ANDROID_CHANGES
	static int levels[5] = {
	ANDROID_LOG_DEBUG, ANDROID_LOG_INFO, ANDROID_LOG_WARN,
	ANDROID_LOG_ERROR, ANDROID_LOG_FATAL
	};
	va_list ap;
	va_start(ap, format);
	__android_log_vprint(levels[level], "mtpd", format, ap);
	va_end(ap);
	#else
	static char *levels = "DIWEF";
	va_list ap;
	fprintf(stderr, "%c: ", levels[level]);
	va_start(ap, format);
	vfprintf(stderr, format, ap);
	va_end(ap);
	fputc('\n', stderr);
	#endif
	}
	}

	void create_socket(int family, int type, char server, char port)
	{
	struct addrinfo hints = {
	.ai_flags = AI_NUMERICSERV,
	.ai_family = family,
	.ai_socktype = type,
	};
	struct addrinfo *records;
	struct addrinfo *r;
	int error;

	log_print(INFO, "Connecting to %s port %s", server, port);

	error = getaddrinfo(server, port, &hints, &records);
	if (error) {
	log_print(FATAL, "Getaddrinfo() %s", (error == EAI_SYSTEM) ?
	strerror(errno) : gai_strerror(error));
	exit(NETWORK_ERROR);
	}

	for (r = records; r; r = r->ai_next) {
	the_socket = socket(r->ai_family, r->ai_socktype, r->ai_protocol);
	if (the_socket != -1) {
	if (connect(the_socket, r->ai_addr, r->ai_addrlen) == 0) {
	break;
	}
	close(the_socket);
	the_socket = -1;
	}
	}

	freeaddrinfo(records);

	if (the_socket == -1) {
	log_print(FATAL, "Connect() %s", strerror(errno));
	exit(NETWORK_ERROR);
	}

	fcntl(the_socket, F_SETFD, FD_CLOEXEC);
	log_print(INFO, "Connection established (socket = %d)", the_socket);
	}

	void start_pppd(int pppox)
	{
	if (pppd_pid) {
	log_print(WARNING, "Pppd is already started (pid = %d)", pppd_pid);
	close(pppox);
	return;
	}

	log_print(INFO, "Starting pppd (pppox = %d)", pppox);

	pppd_pid = fork();
	if (pppd_pid < 0) {
	log_print(FATAL, "Fork() %s", strerror(errno));
	exit(SYSTEM_ERROR);
	}

	if (!pppd_pid) {
	char *args[pppd_argc + 5];
	char number[12];

	sprintf(number, "%d", pppox);
	args[0] = "pppd";
	args[1] = "nodetach";
	args[2] = "pppox";
	args[3] = number;
	memcpy(&args[4], pppd_argv, sizeof(char ) pppd_argc);
	args[4 + pppd_argc] = NULL;

	execvp("pppd", args);
	log_print(FATAL, "Exec() %s", strerror(errno));
	exit(1); /* Pretending a fatal error in pppd. */
	}

	log_print(INFO, "Pppd started (pid = %d)", pppd_pid);
	close(pppox);
	}