server.c

   1 /*
   2  * Copyright (C) 1997-2010 Andre Noll <maan@systemlinux.org>
   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 /**
  11  * \mainpage Paraslash API Reference
  12  *
  13  * Starting points for getting an overview:
  14  *
  15  *
  16  *      - The main programs: \ref server.c, \ref audiod.c, \ref client.c,
  17  *        \ref audioc.c, \ref afh.c
  18  *      - Server: \ref server_command, \ref sender,
  19  *      - Audio file selector: \ref audio_format_handler, \ref afs_table,
  20  *      - Client: \ref receiver, \ref receiver_node, \ref filter, \ref filter_node.
  21  *
  22  *
  23  * The gory details, listed by topic:
  24  *
  25  *      - Audio format handlers: \ref send_common.c \ref mp3_afh.c,
  26  *        \ref ogg_afh.c, \ref aac_afh.c, \ref wma_afh.c,
  27  *      - Decoders: \ref mp3dec_filter.c, \ref oggdec_filter.c,
  28  *        \ref aacdec_filter.c, \ref wmadec_filter.c,
  29  *      - Volume normalizer: \ref compress_filter.c,
  30  *      - Output: \ref alsa_write.c, \ref osx_write.c, \ref oss_write.c,
  31  *      - http: \ref http_recv.c, \ref http_send.c,
  32  *      - udp: \ref udp_recv.c, \ref udp_send.c,
  33  *      - dccp: \ref dccp_recv.c, \ref dccp_send.c,
  34  *      - Audio file selector: \ref afs.c, \ref aft.c, \ref mood.c,
  35  *      - Afs structures: \ref afs_table, \ref audio_file_data,
  36  *        \ref afs_info \ref afh_info,
  37  *      - Afs tables: \ref aft.c, \ref mood.c, \ref playlist.c,
  38  *        \ref attribute.c, \ref score.c,
  39  *      - The virtual streaming system: \ref vss.c, \ref chunk_queue.c.
  40  *
  41  * Lower levels:
  42  *
  43  *      - Scheduling: \ref sched.c, \ref sched.h,
  44  *      - Networking: \ref net.c,
  45  *      - File descriptors: \ref fd.c,
  46  *      - Signals: \ref signal.c,
  47  *      - Daemons: \ref daemon.c,
  48  *      - Strings: \ref string.c, \ref string.h,
  49  *      - Time: \ref time.c,
  50  *      - Spawning processes: \ref exec.c,
  51  *      - Inter process communication: \ref ipc.c,
  52  *      - Blob tables: \ref blob.c,
  53  *      - The error subssystem: \ref error.h.
  54  *      - Access control for paraslash senders: \ref acl.c, \ref acl.h.
  55  *
  56  * Low-level data structures:
  57  *
  58  *      - Doubly linked lists: \ref list.h,
  59  *      - Ring buffer: \ref ringbuffer.c, \ref ringbuffer.h,
  60  *      - Hashing: \ref hash.h, \ref sha1.h, \ref sha1.c,
  61  *      - Crypto: \ref crypt.c.
  62  *      - Forward error correction: \ref fec.c.
  63  */
  64
  65 #include <signal.h>
  66 #include <dirent.h>
  67 #include <sys/time.h>
  68 #include <openssl/rc4.h>
  69 #include <regex.h>
  70 #include <osl.h>
  71
  72 #include "para.h"
  73 #include "error.h"
  74 #include "crypt.h"
  75 #include "server.cmdline.h"
  76 #include "afh.h"
  77 #include "string.h"
  78 #include "afs.h"
  79 #include "server.h"
  80 #include "vss.h"
  81 #include "config.h"
  82 #include "close_on_fork.h"
  83 #include "list.h"
  84 #include "send.h"
  85 #include "net.h"
  86 #include "daemon.h"
  87 #include "ipc.h"
  88 #include "fd.h"
  89 #include "sched.h"
  90 #include "signal.h"
  91 #include "user_list.h"
  92 #include "color.h"
  93
  94 /** Define the array of error lists needed by para_server. */
  95 INIT_SERVER_ERRLISTS;
  96
  97 /** Shut down non-authorized connections after that many seconds. */
  98 #define ALARM_TIMEOUT 10
  99
 100 /**
 101  * Pointer to shared memory area for communication between para_server
 102  * and its children. Exported to vss.c. command.c and to afs.
 103  */
 104 struct misc_meta_data *mmd;
 105
 106 /**
 107  * The configuration of para_server
 108  *
 109  * It also contains the options for the audio file selector, audio format
 110  * handler and all supported senders.
 111  */
 112 struct server_args_info conf;
 113
 114 /** A random value used in child context for authentication. */
 115 uint32_t afs_socket_cookie;
 116
 117 /** The mutex protecting the shared memory area containing the mmd struct. */
 118 int mmd_mutex;
 119
 120 /** The file containing user information (public key, permissions). */
 121 static char *user_list_file = NULL;
 122
 123
 124 /** The task responsible for server command handling. */
 125 struct server_command_task {
 126         /** TCP port on which para_server listens for connections. */
 127         int listen_fd;
 128         /** Copied from para_server's main function. */
 129         int argc;
 130         /** Argument vector passed to para_server's main function. */
 131         char **argv;
 132         /** The command task structure for scheduling. */
 133         struct task task;
 134 };
 135
 136 static int want_colors(void)
 137 {
 138         if (conf.color_arg == color_arg_no)
 139                 return 0;
 140         if (conf.color_arg == color_arg_yes)
 141                 return 1;
 142         if (conf.logfile_given)
 143                 return 0;
 144         return isatty(STDERR_FILENO);
 145 }
 146
 147 static void init_colors_or_die(void)
 148 {
 149         int ret, i;
 150
 151         if (!want_colors())
 152                 return;
 153         daemon_set_flag(DF_COLOR_LOG);
 154         daemon_set_default_log_colors();
 155         for (i = 0; i < conf.log_color_given; i++) {
 156                 ret = daemon_set_log_color(conf.log_color_arg[i]);
 157                 if (ret < 0)
 158                         exit(EXIT_FAILURE);
 159         }
 160 }
 161
 162 /*
 163  * setup shared memory area and get mutex for locking
 164  */
 165 static void init_ipc_or_die(void)
 166 {
 167         void *shm;
 168         int shmid, ret = shm_new(sizeof(struct misc_meta_data));
 169
 170         if (ret < 0)
 171                 goto err_out;
 172         shmid = ret;
 173         ret = shm_attach(shmid, ATTACH_RW, &shm);
 174         shm_destroy(shmid);
 175         if (ret < 0)
 176                 goto err_out;
 177         mmd = shm;
 178
 179         ret = mutex_new();
 180         if (ret < 0)
 181                 goto err_out;
 182         mmd_mutex = ret;
 183
 184         mmd->num_played = 0;
 185         mmd->num_commands = 0;
 186         mmd->events = 0;
 187         mmd->num_connects = 0;
 188         mmd->active_connections = 0;
 189         mmd->vss_status_flags = VSS_NEXT;
 190         mmd->new_vss_status_flags = VSS_NEXT;
 191         return;
 192 err_out:
 193         PARA_EMERG_LOG("%s\n", para_strerror(-ret));
 194         exit(EXIT_FAILURE);
 195 }
 196
 197 /**
 198  * (Re-)read the server configuration files.
 199  *
 200  * \param override Passed to gengetopt to activate the override feature.
 201  *
 202  * This function also re-opens the logfile and sets the global \a
 203  * user_list_file variable.
 204  */
 205 void parse_config_or_die(int override)
 206 {
 207         char *home = para_homedir();
 208         int ret;
 209         char *cf;
 210
 211         daemon_close_log();
 212         if (conf.config_file_given)
 213                 cf = para_strdup(conf.config_file_arg);
 214         else
 215                 cf = make_message("%s/.paraslash/server.conf", home);
 216         free(user_list_file);
 217         if (!conf.user_list_given)
 218                 user_list_file = make_message("%s/.paraslash/server.users", home);
 219         else
 220                 user_list_file = para_strdup(conf.user_list_arg);
 221         ret = file_exists(cf);
 222         if (conf.config_file_given && !ret)  {
 223                 ret = -1;
 224                 PARA_EMERG_LOG("can not read config file %s\n", cf);
 225                 goto out;
 226         }
 227         if (ret) {
 228                 int tmp = conf.daemon_given;
 229                 struct server_cmdline_parser_params params = {
 230                         .override = override,
 231                         .initialize = 0,
 232                         .check_required = 1,
 233                         .check_ambiguity = 0,
 234                         .print_errors = !conf.daemon_given
 235                 };
 236                 server_cmdline_parser_config_file(cf, &conf, &params);
 237                 conf.daemon_given = tmp;
 238         }
 239         if (conf.logfile_given) {
 240                 daemon_set_logfile(conf.logfile_arg);
 241                 daemon_open_log_or_die();
 242         }
 243         daemon_set_loglevel(conf.loglevel_arg);
 244         init_colors_or_die();
 245         daemon_set_flag(DF_LOG_PID);
 246         daemon_set_flag(DF_LOG_LL);
 247         daemon_set_flag(DF_LOG_TIME);
 248         if (conf.log_timing_given)
 249                 daemon_set_flag(DF_LOG_TIMING);
 250         ret = 1;
 251 out:
 252         free(cf);
 253         free(home);
 254         if (ret > 0)
 255                 return;
 256         free(user_list_file);
 257         user_list_file = NULL;
 258         exit(EXIT_FAILURE);
 259 }
 260
 261 static void signal_pre_select(struct sched *s, struct task *t)
 262 {
 263         struct signal_task *st = container_of(t, struct signal_task, task);
 264         para_fd_set(st->fd, &s->rfds, &s->max_fileno);
 265 }
 266
 267 /*
 268  * called when server gets SIGHUP or when client invokes hup command.
 269  */
 270 static void handle_sighup(void)
 271 {
 272         PARA_NOTICE_LOG("SIGHUP\n");
 273         parse_config_or_die(1); /* reopens log */
 274         init_user_list(user_list_file); /* reload user list */
 275         if (mmd->afs_pid)
 276                 kill(mmd->afs_pid, SIGHUP);
 277 }
 278
 279 static void signal_post_select(struct sched *s, struct task *t)
 280 {
 281         struct signal_task *st = container_of(t, struct signal_task, task);
 282
 283         if (!FD_ISSET(st->fd, &s->rfds))
 284                 return;
 285
 286         st->signum = para_next_signal();
 287         switch (st->signum) {
 288         case SIGHUP:
 289                 handle_sighup();
 290                 break;
 291         case SIGCHLD:
 292                 for (;;) {
 293                         pid_t pid;
 294                         int ret = para_reap_child(&pid);
 295                         if (ret <= 0)
 296                                 break;
 297                         if (pid != mmd->afs_pid)
 298                                 continue;
 299                         PARA_EMERG_LOG("fatal: afs died\n");
 300                         kill(0, SIGTERM);
 301                         goto cleanup;
 302                 }
 303                 break;
 304         /* die on sigint/sigterm. Kill all children too. */
 305         case SIGINT:
 306         case SIGTERM:
 307                 PARA_EMERG_LOG("terminating on signal %d\n", st->signum);
 308                 kill(0, SIGTERM);
 309                 /*
 310                  * We must wait for afs because afs catches SIGINT/SIGTERM.
 311                  * Before reacting to the signal, afs might want to use the
 312                  * shared memory area and the mmd mutex.  If we destroy this
 313                  * mutex too early and afs tries to lock the shared memory
 314                  * area, the call to mutex_lock() will fail and terminate the
 315                  * afs process. This leads to dirty osl tables.
 316                  *
 317                  * There's no such problem with the other children of the
 318                  * server process (the command handlers) as these reset their
 319                  * SIGINT/SIGTERM handlers to the default action, i.e.  these
 320                  * processes get killed immediately by the above kill().
 321                  */
 322                 PARA_INFO_LOG("waiting for afs (pid %d) to die\n",
 323                         (int)mmd->afs_pid);
 324                 waitpid(mmd->afs_pid, NULL, 0);
 325 cleanup:
 326                 free(mmd->afd.afhi.chunk_table);
 327                 close_listed_fds();
 328                 mutex_destroy(mmd_mutex);
 329                 shm_detach(mmd);
 330                 exit(EXIT_FAILURE);
 331         }
 332 }
 333
 334 static void init_signal_task(void)
 335 {
 336         static struct signal_task signal_task_struct,
 337                 *st = &signal_task_struct;
 338
 339         st->task.pre_select = signal_pre_select;
 340         st->task.post_select = signal_post_select;
 341         sprintf(st->task.status, "signal task");
 342
 343         PARA_NOTICE_LOG("setting up signal handling\n");
 344         st->fd = para_signal_init(); /* always successful */
 345         para_install_sighandler(SIGINT);
 346         para_install_sighandler(SIGTERM);
 347         para_install_sighandler(SIGHUP);
 348         para_install_sighandler(SIGCHLD);
 349         para_sigaction(SIGPIPE, SIG_IGN);
 350         add_close_on_fork_list(st->fd);
 351         register_task(&st->task);
 352 }
 353
 354 static void command_pre_select(struct sched *s, struct task *t)
 355 {
 356         struct server_command_task *sct = container_of(t, struct server_command_task, task);
 357         para_fd_set(sct->listen_fd, &s->rfds, &s->max_fileno);
 358 }
 359
 360 static void command_post_select(struct sched *s, struct task *t)
 361 {
 362         struct server_command_task *sct = container_of(t, struct server_command_task, task);
 363
 364         int new_fd, ret, i;
 365         char *peer_name;
 366         pid_t child_pid;
 367         uint32_t *chunk_table;
 368
 369         if (!FD_ISSET(sct->listen_fd, &s->rfds))
 370                 return;
 371         ret = para_accept(sct->listen_fd, NULL, 0);
 372         if (ret < 0)
 373                 goto out;
 374         new_fd = ret;
 375         peer_name = remote_name(new_fd);
 376         PARA_INFO_LOG("got connection from %s, forking\n", peer_name);
 377         mmd->num_connects++;
 378         mmd->active_connections++;
 379         /*
 380          * The chunk table is a pointer located in the mmd struct that points
 381          * to dynamically allocated memory, i.e. it must be freed by the parent
 382          * and the child. However, as the mmd struct is in a shared memory
 383          * area, there's no guarantee that after the fork this pointer is still
 384          * valid in child context. As it is not used in the child anyway, we
 385          * save it to a local variable before the fork and free the memory via
 386          * that copy in the child directly after the fork.
 387          */
 388         chunk_table = mmd->afd.afhi.chunk_table;
 389         child_pid = fork();
 390         if (child_pid < 0) {
 391                 ret = -ERRNO_TO_PARA_ERROR(errno);
 392                 goto out;
 393         }
 394         if (child_pid) {
 395                 close(new_fd);
 396                 /* parent keeps accepting connections */
 397                 return;
 398         }
 399         /* mmd might already have changed at this point */
 400         free(chunk_table);
 401         alarm(ALARM_TIMEOUT);
 402         close_listed_fds();
 403         para_signal_shutdown();
 404         /*
 405          * put info on who we are serving into argv[0] to make
 406          * client ip visible in top/ps
 407          */
 408         for (i = sct->argc - 1; i >= 0; i--)
 409                 memset(sct->argv[i], 0, strlen(sct->argv[i]));
 410         sprintf(sct->argv[0], "para_server (serving %s)", peer_name);
 411         return handle_connect(new_fd, peer_name);
 412 out:
 413         if (ret < 0)
 414                 PARA_CRIT_LOG("%s\n", para_strerror(-ret));
 415 }
 416
 417 static void init_server_command_task(int argc, char **argv)
 418 {
 419         int ret;
 420         static struct server_command_task server_command_task_struct,
 421                 *sct = &server_command_task_struct;
 422
 423         PARA_NOTICE_LOG("initializing tcp command socket\n");
 424         sct->task.pre_select = command_pre_select;
 425         sct->task.post_select = command_post_select;
 426         sct->argc = argc;
 427         sct->argv = argv;
 428         ret = para_listen_simple(IPPROTO_TCP, conf.port_arg);
 429         if (ret < 0)
 430                 goto err;
 431         sct->listen_fd = ret;
 432         ret = mark_fd_nonblocking(sct->listen_fd);
 433         if (ret < 0)
 434                 goto err;
 435         add_close_on_fork_list(sct->listen_fd); /* child doesn't need the listener */
 436         register_task(&sct->task);
 437         return;
 438 err:
 439         PARA_EMERG_LOG("%s\n", para_strerror(-ret));
 440         exit(EXIT_FAILURE);
 441 }
 442
 443 static int init_afs(void)
 444 {
 445         int ret, afs_server_socket[2];
 446         pid_t afs_pid;
 447
 448         ret = socketpair(PF_UNIX, SOCK_DGRAM, 0, afs_server_socket);
 449         if (ret < 0)
 450                 exit(EXIT_FAILURE);
 451         get_random_bytes_or_die((unsigned char *)&afs_socket_cookie,
 452                 sizeof(afs_socket_cookie));
 453         afs_pid = fork();
 454         if (afs_pid < 0)
 455                 exit(EXIT_FAILURE);
 456         if (afs_pid == 0) { /* child (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 tmp_sigchld_handler(__a_unused int s)
 472 {
 473         PARA_EMERG_LOG("caught early SIGCHLD\n");
 474         exit(EXIT_FAILURE);
 475 }
 476
 477 static void server_init(int argc, char **argv)
 478 {
 479         struct server_cmdline_parser_params params = {
 480                 .override = 0,
 481                 .initialize = 1,
 482                 .check_required = 0,
 483                 .check_ambiguity = 0,
 484                 .print_errors = 1
 485         };
 486         int afs_socket;
 487
 488         valid_fd_012();
 489         init_random_seed_or_die();
 490         /* parse command line options */
 491         server_cmdline_parser_ext(argc, argv, &conf, &params);
 492         HANDLE_VERSION_FLAG("server", conf);
 493         drop_privileges_or_die(conf.user_arg, conf.group_arg);
 494         /* parse config file, open log and set defaults */
 495         parse_config_or_die(0);
 496         log_welcome("para_server");
 497         init_ipc_or_die(); /* init mmd struct and mmd->lock */
 498         /* make sure, the global now pointer is uptodate */
 499         gettimeofday(now, NULL);
 500         server_uptime(UPTIME_SET); /* reset server uptime */
 501         init_user_list(user_list_file);
 502         /* become daemon */
 503         if (conf.daemon_given)
 504                 daemonize();
 505         PARA_NOTICE_LOG("initializing audio format handlers\n");
 506         afh_init();
 507
 508         /*
 509          * Although afs uses its own signal handling we must ignore SIGUSR1
 510          * _before_ the afs child process gets born by init_afs() below.  It's
 511          * racy to do this in the child because the parent might send SIGUSR1
 512          * before the child gets a chance to ignore this signal -- only the
 513          * good die young.
 514          */
 515         para_sigaction(SIGUSR1, SIG_IGN);
 516         /*
 517          * We have to install a SIGCHLD handler before the afs process is being
 518          * forked off. Otherwise, para_server does not notice if afs dies before
 519          * the SIGCHLD handler has been installed by init_signal_task() below.
 520          */
 521         para_sigaction(SIGCHLD, tmp_sigchld_handler);
 522         PARA_NOTICE_LOG("initializing the audio file selector\n");
 523         afs_socket = init_afs();
 524         init_signal_task();
 525         PARA_NOTICE_LOG("initializing virtual streaming system\n");
 526         init_vss_task(afs_socket);
 527         init_server_command_task(argc, argv);
 528         PARA_NOTICE_LOG("server init complete\n");
 529 }
 530
 531 static void status_refresh(void)
 532 {
 533         static int prev_uptime = -1, prev_events = -1;
 534         int uptime = server_uptime(UPTIME_GET), ret = 1;
 535
 536         if (prev_events != mmd->events)
 537                 goto out;
 538         if (mmd->new_vss_status_flags != mmd->vss_status_flags)
 539                 goto out_inc_events;
 540         if (uptime / 60 != prev_uptime / 60)
 541                 goto out_inc_events;
 542         return;
 543 out_inc_events:
 544         mmd->events++;
 545 out:
 546         prev_uptime = uptime;
 547         prev_events = mmd->events;
 548         mmd->vss_status_flags = mmd->new_vss_status_flags;
 549         if (ret) {
 550                 PARA_DEBUG_LOG("%d events, forcing status update\n",
 551                         mmd->events);
 552                 killpg(0, SIGUSR1);
 553         }
 554 }
 555
 556 static int server_select(int max_fileno, fd_set *readfds, fd_set *writefds,
 557                 struct timeval *timeout_tv)
 558 {
 559         int ret;
 560
 561         status_refresh();
 562         mutex_unlock(mmd_mutex);
 563         ret = para_select(max_fileno + 1, readfds, writefds, timeout_tv);
 564         mutex_lock(mmd_mutex);
 565         return ret;
 566 }
 567
 568 /**
 569  * The main function of para_server.
 570  *
 571  * \param argc Usual argument count.
 572  * \param argv Usual argument vector.
 573  *
 574  * \return EXIT_SUCCESS or EXIT_FAILURE.
 575  */
 576 int main(int argc, char *argv[])
 577 {
 578         int ret;
 579         static struct sched s = {
 580                 .default_timeout = {
 581                         .tv_sec = 1,
 582                         .tv_usec = 0
 583                 },
 584                 .select_function = server_select
 585         };
 586         server_init(argc, argv);
 587         mutex_lock(mmd_mutex);
 588         ret = schedule(&s);
 589         if (ret < 0) {
 590                 PARA_EMERG_LOG("%s\n", para_strerror(-ret));
 591                 exit(EXIT_FAILURE);
 592         }
 593         exit(EXIT_SUCCESS);
 594 }