server.c

   1 /*
   2  * Copyright (C) 1997-2014 Andre Noll <maan@tuebingen.mpg.de>
   3  *
   4  * Licensed under the GPL v2. For licencing details see COPYING.
   5  */
   6
   7 /** \file server.c Paraslash's main server. */
   8
   9 /**
  10  * \mainpage Main data structures:
  11  *
  12  *      - Server: \ref server_command, \ref sender,
  13  *      - Audio file selector: \ref afs_info, \ref afs_table,
  14  *      - Audio format handler: \ref audio_format_handler, \ref afh_info
  15  *      - Receivers/filters/writers: \ref receiver, \ref receiver_node,
  16  *        \ref filter, \ref filter_node, \ref writer_node, \ref writer.
  17  *
  18  * Selected APIs:
  19  *
  20  *      - Scheduling: \ref sched.h,
  21  *      - Buffer trees: \ref buffer_tree.h,
  22  *      - Sideband API: \ref sideband.h,
  23  *      - Crypto: \ref crypt.h, \ref crypt_backend.h,
  24  *      - Error subsystem: \ref error.h, \ref error2.c,
  25  *      - Inter process communication: \ref ipc.h,
  26  *      - Forward error correction: \ref fec.h,
  27  *      - Daemons: \ref daemon.h,
  28  *      - Mixer API: \ref mix.h,
  29  *      - Interactive sessions: \ref interactive.h,
  30  *      - File descriptors: \ref fd.h,
  31  *      - Signals: \ref signal.h,
  32  *      - Networking: \ref net.h,
  33  *      - Time: \ref time.c,
  34  *      - Doubly linked lists: \ref list.h.
  35  */
  36
  37 #include <netinet/in.h>
  38 #include <sys/socket.h>
  39 #include <signal.h>
  40 #include <regex.h>
  41 #include <osl.h>
  42 #include <sys/types.h>
  43 #include <arpa/inet.h>
  44 #include <sys/un.h>
  45 #include <netdb.h>
  46
  47 #include "para.h"
  48 #include "error.h"
  49 #include "crypt.h"
  50 #include "server.cmdline.h"
  51 #include "afh.h"
  52 #include "string.h"
  53 #include "afs.h"
  54 #include "server.h"
  55 #include "list.h"
  56 #include "send.h"
  57 #include "sched.h"
  58 #include "vss.h"
  59 #include "config.h"
  60 #include "close_on_fork.h"
  61 #include "net.h"
  62 #include "daemon.h"
  63 #include "ipc.h"
  64 #include "fd.h"
  65 #include "signal.h"
  66 #include "user_list.h"
  67 #include "color.h"
  68 #include "ggo.h"
  69 #include "version.h"
  70
  71 __printf_2_3 void (*para_log)(int, const char*, ...) = daemon_log;
  72
  73 /** Define the array of error lists needed by para_server. */
  74 INIT_SERVER_ERRLISTS;
  75
  76 /** Shut down non-authorized connections after that many seconds. */
  77 #define ALARM_TIMEOUT 10
  78
  79 /**
  80  * Pointer to shared memory area for communication between para_server
  81  * and its children. Exported to vss.c. command.c and to afs.
  82  */
  83 struct misc_meta_data *mmd;
  84
  85 /**
  86  * The configuration of para_server
  87  *
  88  * It also contains the options for the audio file selector, audio format
  89  * handler and all supported senders.
  90  */
  91 struct server_args_info conf;
  92
  93 /** A random value used in child context for authentication. */
  94 uint32_t afs_socket_cookie;
  95
  96 /** The mutex protecting the shared memory area containing the mmd struct. */
  97 int mmd_mutex;
  98
  99 /** The file containing user information (public key, permissions). */
 100 static char *user_list_file = NULL;
 101
 102 static struct sched sched;
 103
 104 /** The task responsible for server command handling. */
 105 struct server_command_task {
 106         /** TCP port on which para_server listens for connections. */
 107         int listen_fd;
 108         /** Copied from para_server's main function. */
 109         int argc;
 110         /** Argument vector passed to para_server's main function. */
 111         char **argv;
 112         /** The command task structure for scheduling. */
 113         struct task *task;
 114 };
 115
 116 /**
 117  * Return the list of tasks for the server process.
 118  *
 119  * This is called from \a com_tasks(). The helper is necessary since command
 120  * handlers can not access the scheduler structure directly.
 121  *
 122  * \return A dynamically allocated string that must be freed by the caller.
 123  */
 124 char *server_get_tasks(void)
 125 {
 126         return get_task_list(&sched);
 127 }
 128
 129 static int want_colors(void)
 130 {
 131         if (conf.color_arg == color_arg_no)
 132                 return 0;
 133         if (conf.color_arg == color_arg_yes)
 134                 return 1;
 135         if (conf.logfile_given)
 136                 return 0;
 137         return isatty(STDERR_FILENO);
 138 }
 139
 140 static void init_colors_or_die(void)
 141 {
 142         int i;
 143
 144         if (!want_colors())
 145                 return;
 146         daemon_set_flag(DF_COLOR_LOG);
 147         daemon_set_default_log_colors();
 148         for (i = 0; i < conf.log_color_given; i++)
 149                 daemon_set_log_color_or_die(conf.log_color_arg[i]);
 150 }
 151
 152 /*
 153  * setup shared memory area and get mutex for locking
 154  */
 155 static void init_ipc_or_die(void)
 156 {
 157         void *shm;
 158         int shmid, ret = shm_new(sizeof(struct misc_meta_data));
 159
 160         if (ret < 0)
 161                 goto err_out;
 162         shmid = ret;
 163         ret = shm_attach(shmid, ATTACH_RW, &shm);
 164         shm_destroy(shmid);
 165         if (ret < 0)
 166                 goto err_out;
 167         mmd = shm;
 168
 169         ret = mutex_new();
 170         if (ret < 0)
 171                 goto err_out;
 172         mmd_mutex = ret;
 173
 174         mmd->num_played = 0;
 175         mmd->num_commands = 0;
 176         mmd->events = 0;
 177         mmd->num_connects = 0;
 178         mmd->active_connections = 0;
 179         mmd->vss_status_flags = VSS_NEXT;
 180         mmd->new_vss_status_flags = VSS_NEXT;
 181         return;
 182 err_out:
 183         PARA_EMERG_LOG("%s\n", para_strerror(-ret));
 184         exit(EXIT_FAILURE);
 185 }
 186
 187 /**
 188  * (Re-)read the server configuration files.
 189  *
 190  * \param override Passed to gengetopt to activate the override feature.
 191  *
 192  * This function also re-opens the logfile and sets the global \a
 193  * user_list_file variable.
 194  */
 195 void parse_config_or_die(int override)
 196 {
 197         char *home = para_homedir();
 198         int ret;
 199         char *cf;
 200
 201         daemon_close_log();
 202         if (conf.config_file_given)
 203                 cf = para_strdup(conf.config_file_arg);
 204         else
 205                 cf = make_message("%s/.paraslash/server.conf", home);
 206         free(user_list_file);
 207         if (!conf.user_list_given)
 208                 user_list_file = make_message("%s/.paraslash/server.users", home);
 209         else
 210                 user_list_file = para_strdup(conf.user_list_arg);
 211         ret = file_exists(cf);
 212         if (conf.config_file_given && !ret)  {
 213                 ret = -1;
 214                 PARA_EMERG_LOG("can not read config file %s\n", cf);
 215                 goto out;
 216         }
 217         if (ret) {
 218                 int tmp = conf.daemon_given;
 219                 struct server_cmdline_parser_params params = {
 220                         .override = override,
 221                         .initialize = 0,
 222                         .check_required = 1,
 223                         .check_ambiguity = 0,
 224                         .print_errors = !conf.daemon_given
 225                 };
 226                 server_cmdline_parser_config_file(cf, &conf, &params);
 227                 daemon_set_loglevel(conf.loglevel_arg);
 228                 conf.daemon_given = tmp;
 229         }
 230         if (conf.logfile_given) {
 231                 daemon_set_logfile(conf.logfile_arg);
 232                 daemon_open_log_or_die();
 233         }
 234         init_colors_or_die();
 235         daemon_set_flag(DF_LOG_PID);
 236         daemon_set_flag(DF_LOG_LL);
 237         daemon_set_flag(DF_LOG_TIME);
 238         if (conf.log_timing_given)
 239                 daemon_set_flag(DF_LOG_TIMING);
 240         ret = 1;
 241 out:
 242         free(cf);
 243         free(home);
 244         if (ret > 0)
 245                 return;
 246         free(user_list_file);
 247         user_list_file = NULL;
 248         exit(EXIT_FAILURE);
 249 }
 250
 251 static void signal_pre_select(struct sched *s, void *context)
 252 {
 253         struct signal_task *st = context;
 254         para_fd_set(st->fd, &s->rfds, &s->max_fileno);
 255 }
 256
 257 /*
 258  * called when server gets SIGHUP or when client invokes hup command.
 259  */
 260 static void handle_sighup(void)
 261 {
 262         PARA_NOTICE_LOG("SIGHUP\n");
 263         parse_config_or_die(1); /* reopens log */
 264         init_user_list(user_list_file); /* reload user list */
 265         if (mmd->afs_pid)
 266                 kill(mmd->afs_pid, SIGHUP);
 267 }
 268
 269 static int signal_post_select(struct sched *s, __a_unused void *context)
 270 {
 271         int signum = para_next_signal(&s->rfds);
 272
 273         switch (signum) {
 274         case 0:
 275                 return 0;
 276         case SIGHUP:
 277                 handle_sighup();
 278                 break;
 279         case SIGCHLD:
 280                 for (;;) {
 281                         pid_t pid;
 282                         int ret = para_reap_child(&pid);
 283                         if (ret <= 0)
 284                                 break;
 285                         if (pid != mmd->afs_pid)
 286                                 continue;
 287                         PARA_EMERG_LOG("fatal: afs died\n");
 288                         kill(0, SIGTERM);
 289                         goto cleanup;
 290                 }
 291                 break;
 292         /* die on sigint/sigterm. Kill all children too. */
 293         case SIGINT:
 294         case SIGTERM:
 295                 PARA_EMERG_LOG("terminating on signal %d\n", signum);
 296                 kill(0, SIGTERM);
 297                 /*
 298                  * We must wait for afs because afs catches SIGINT/SIGTERM.
 299                  * Before reacting to the signal, afs might want to use the
 300                  * shared memory area and the mmd mutex.  If we destroy this
 301                  * mutex too early and afs tries to lock the shared memory
 302                  * area, the call to mutex_lock() will fail and terminate the
 303                  * afs process. This leads to dirty osl tables.
 304                  *
 305                  * There's no such problem with the other children of the
 306                  * server process (the command handlers) as these reset their
 307                  * SIGINT/SIGTERM handlers to the default action, i.e.  these
 308                  * processes get killed immediately by the above kill().
 309                  */
 310                 PARA_INFO_LOG("waiting for afs (pid %d) to die\n",
 311                         (int)mmd->afs_pid);
 312                 waitpid(mmd->afs_pid, NULL, 0);
 313 cleanup:
 314                 free(mmd->afd.afhi.chunk_table);
 315                 close_listed_fds();
 316                 mutex_destroy(mmd_mutex);
 317                 shm_detach(mmd);
 318                 exit(EXIT_FAILURE);
 319         }
 320         return 0;
 321 }
 322
 323 static void init_signal_task(void)
 324 {
 325         static struct signal_task signal_task_struct,
 326                 *st = &signal_task_struct;
 327
 328         PARA_NOTICE_LOG("setting up signal handling\n");
 329         st->fd = para_signal_init(); /* always successful */
 330         para_install_sighandler(SIGINT);
 331         para_install_sighandler(SIGTERM);
 332         para_install_sighandler(SIGHUP);
 333         para_install_sighandler(SIGCHLD);
 334         para_sigaction(SIGPIPE, SIG_IGN);
 335         add_close_on_fork_list(st->fd);
 336         st->task = task_register(&(struct task_info) {
 337                 .name = "signal",
 338                 .pre_select = signal_pre_select,
 339                 .post_select = signal_post_select,
 340                 .context = st,
 341
 342         }, &sched);
 343 }
 344
 345 static void command_pre_select(struct sched *s, void *context)
 346 {
 347         struct server_command_task *sct = context;
 348         para_fd_set(sct->listen_fd, &s->rfds, &s->max_fileno);
 349 }
 350
 351 static int command_post_select(struct sched *s, void *context)
 352 {
 353         struct server_command_task *sct = context;
 354
 355         int new_fd, ret, i;
 356         char *peer_name;
 357         pid_t child_pid;
 358         uint32_t *chunk_table;
 359
 360         ret = para_accept(sct->listen_fd, &s->rfds, NULL, 0, &new_fd);
 361         if (ret <= 0)
 362                 goto out;
 363         peer_name = remote_name(new_fd);
 364         PARA_INFO_LOG("got connection from %s, forking\n", peer_name);
 365         mmd->num_connects++;
 366         mmd->active_connections++;
 367         /*
 368          * The chunk table is a pointer located in the mmd struct that points
 369          * to dynamically allocated memory, i.e. it must be freed by the parent
 370          * and the child. However, as the mmd struct is in a shared memory
 371          * area, there's no guarantee that after the fork this pointer is still
 372          * valid in child context. As it is not used in the child anyway, we
 373          * save it to a local variable before the fork and free the memory via
 374          * that copy in the child directly after the fork.
 375          */
 376         chunk_table = mmd->afd.afhi.chunk_table;
 377         child_pid = fork();
 378         if (child_pid < 0) {
 379                 ret = -ERRNO_TO_PARA_ERROR(errno);
 380                 goto out;
 381         }
 382         if (child_pid) {
 383                 /* avoid problems with non-fork-safe PRNGs */
 384                 unsigned char buf[16];
 385                 get_random_bytes_or_die(buf, sizeof(buf));
 386                 close(new_fd);
 387                 /* parent keeps accepting connections */
 388                 return 0;
 389         }
 390         /* mmd might already have changed at this point */
 391         free(chunk_table);
 392         alarm(ALARM_TIMEOUT);
 393         close_listed_fds();
 394         para_signal_shutdown();
 395         /*
 396          * put info on who we are serving into argv[0] to make
 397          * client ip visible in top/ps
 398          */
 399         for (i = sct->argc - 1; i >= 0; i--)
 400                 memset(sct->argv[i], 0, strlen(sct->argv[i]));
 401         sprintf(sct->argv[0], "para_server (serving %s)", peer_name);
 402         handle_connect(new_fd, peer_name);
 403         /* never reached*/
 404 out:
 405         if (ret < 0)
 406                 PARA_CRIT_LOG("%s\n", para_strerror(-ret));
 407         return 0;
 408 }
 409
 410 static void init_server_command_task(int argc, char **argv)
 411 {
 412         int ret;
 413         static struct server_command_task server_command_task_struct,
 414                 *sct = &server_command_task_struct;
 415
 416         PARA_NOTICE_LOG("initializing tcp command socket\n");
 417         sct->argc = argc;
 418         sct->argv = argv;
 419         ret = para_listen_simple(IPPROTO_TCP, conf.port_arg);
 420         if (ret < 0)
 421                 goto err;
 422         sct->listen_fd = ret;
 423         ret = mark_fd_nonblocking(sct->listen_fd);
 424         if (ret < 0)
 425                 goto err;
 426         add_close_on_fork_list(sct->listen_fd); /* child doesn't need the listener */
 427         sct->task = task_register(&(struct task_info) {
 428                 .name = "server command",
 429                 .pre_select = command_pre_select,
 430                 .post_select = command_post_select,
 431                 .context = sct,
 432         }, &sched);
 433         return;
 434 err:
 435         PARA_EMERG_LOG("%s\n", para_strerror(-ret));
 436         exit(EXIT_FAILURE);
 437 }
 438
 439 static int init_afs(int argc, char **argv)
 440 {
 441         int ret, afs_server_socket[2];
 442         pid_t afs_pid;
 443
 444         ret = socketpair(PF_UNIX, SOCK_DGRAM, 0, afs_server_socket);
 445         if (ret < 0)
 446                 exit(EXIT_FAILURE);
 447         get_random_bytes_or_die((unsigned char *)&afs_socket_cookie,
 448                 sizeof(afs_socket_cookie));
 449         afs_pid = fork();
 450         if (afs_pid < 0)
 451                 exit(EXIT_FAILURE);
 452         if (afs_pid == 0) { /* child (afs) */
 453                 int i;
 454                 for (i = argc - 1; i >= 0; i--)
 455                         memset(argv[i], 0, strlen(argv[i]));
 456                 sprintf(argv[0], "para_server (afs)");
 457                 close(afs_server_socket[0]);
 458                 afs_init(afs_socket_cookie, afs_server_socket[1]);
 459         }
 460         mmd->afs_pid = afs_pid;
 461         close(afs_server_socket[1]);
 462         ret = mark_fd_nonblocking(afs_server_socket[0]);
 463         if (ret < 0)
 464                 exit(EXIT_FAILURE);
 465         add_close_on_fork_list(afs_server_socket[0]);
 466         PARA_INFO_LOG("afs_socket: %d, afs_socket_cookie: %u\n",
 467                 afs_server_socket[0], (unsigned) afs_socket_cookie);
 468         return afs_server_socket[0];
 469 }
 470
 471 __noreturn static void print_help_and_die(void)
 472 {
 473         struct ggo_help h = DEFINE_GGO_HELP(server);
 474         bool d = conf.detailed_help_given;
 475
 476         ggo_print_help(&h, d? GPH_STANDARD_FLAGS_DETAILED : GPH_STANDARD_FLAGS);
 477         exit(0);
 478 }
 479
 480 static void server_init(int argc, char **argv)
 481 {
 482         struct server_cmdline_parser_params params = {
 483                 .override = 0,
 484                 .initialize = 1,
 485                 .check_required = 0,
 486                 .check_ambiguity = 0,
 487                 .print_errors = 1
 488         };
 489         int afs_socket;
 490
 491         valid_fd_012();
 492         init_random_seed_or_die();
 493         /* parse command line options */
 494         server_cmdline_parser_ext(argc, argv, &conf, &params);
 495         daemon_set_loglevel(conf.loglevel_arg);
 496         version_handle_flag("server", conf.version_given);
 497         if (conf.help_given || conf.detailed_help_given)
 498                 print_help_and_die();
 499         daemon_drop_privileges_or_die(conf.user_arg, conf.group_arg);
 500         /* parse config file, open log and set defaults */
 501         parse_config_or_die(0);
 502         daemon_log_welcome("para_server");
 503         init_ipc_or_die(); /* init mmd struct and mmd->lock */
 504         daemon_set_start_time();
 505         init_user_list(user_list_file);
 506         /* become daemon */
 507         if (conf.daemon_given)
 508                 daemonize(true /* parent waits for SIGTERM */);
 509         PARA_NOTICE_LOG("initializing audio format handlers\n");
 510         afh_init();
 511
 512         /*
 513          * Although afs uses its own signal handling we must ignore SIGUSR1
 514          * _before_ the afs child process gets born by init_afs() below.  It's
 515          * racy to do this in the child because the parent might send SIGUSR1
 516          * before the child gets a chance to ignore this signal -- only the
 517          * good die young.
 518          */
 519         para_sigaction(SIGUSR1, SIG_IGN);
 520         /*
 521          * We have to block SIGCHLD before the afs process is being forked off.
 522          * Otherwise, para_server does not notice if afs dies before the
 523          * SIGCHLD handler has been installed for the parent process by
 524          * init_signal_task() below.
 525          */
 526         para_block_signal(SIGCHLD);
 527         PARA_NOTICE_LOG("initializing the audio file selector\n");
 528         afs_socket = init_afs(argc, argv);
 529         init_signal_task();
 530         para_unblock_signal(SIGCHLD);
 531         PARA_NOTICE_LOG("initializing virtual streaming system\n");
 532         init_vss_task(afs_socket, &sched);
 533         init_server_command_task(argc, argv);
 534         if (conf.daemon_given)
 535                 kill(getppid(), SIGTERM);
 536         PARA_NOTICE_LOG("server init complete\n");
 537 }
 538
 539 static void status_refresh(void)
 540 {
 541         static int prev_uptime = -1, prev_events = -1;
 542         int uptime = daemon_get_uptime(now);
 543
 544         if (prev_events != mmd->events)
 545                 goto out;
 546         if (mmd->new_vss_status_flags != mmd->vss_status_flags)
 547                 goto out_inc_events;
 548         if (uptime / 60 != prev_uptime / 60)
 549                 goto out_inc_events;
 550         return;
 551 out_inc_events:
 552         mmd->events++;
 553 out:
 554         prev_uptime = uptime;
 555         prev_events = mmd->events;
 556         mmd->vss_status_flags = mmd->new_vss_status_flags;
 557         PARA_DEBUG_LOG("%d events, forcing status update\n", mmd->events);
 558         killpg(0, SIGUSR1);
 559 }
 560
 561 static int server_select(int max_fileno, fd_set *readfds, fd_set *writefds,
 562                 struct timeval *timeout_tv)
 563 {
 564         int ret;
 565
 566         status_refresh();
 567         mutex_unlock(mmd_mutex);
 568         ret = para_select(max_fileno + 1, readfds, writefds, timeout_tv);
 569         mutex_lock(mmd_mutex);
 570         return ret;
 571 }
 572
 573 /**
 574  * The main function of para_server.
 575  *
 576  * \param argc Usual argument count.
 577  * \param argv Usual argument vector.
 578  *
 579  * \return EXIT_SUCCESS or EXIT_FAILURE.
 580  */
 581 int main(int argc, char *argv[])
 582 {
 583         int ret;
 584
 585         sched.default_timeout.tv_sec = 1;
 586         sched.select_function = server_select;
 587
 588         server_init(argc, argv);
 589         mutex_lock(mmd_mutex);
 590         ret = schedule(&sched);
 591         sched_shutdown(&sched);
 592         if (ret < 0) {
 593                 PARA_EMERG_LOG("%s\n", para_strerror(-ret));
 594                 exit(EXIT_FAILURE);
 595         }
 596         exit(EXIT_SUCCESS);
 597 }