server.c

   1 /*
   2  * Copyright (C) 1997-2009 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 mood, \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, \ref ogg_afh.c, \ref aac_afh.c,
  26  *      - Decoders: \ref mp3dec_filter.c, \ref oggdec_filter.c, \ref aacdec_filter.c,
  27  *      - Volume normalizer: \ref compress_filter.c,
  28  *      - Output: \ref alsa_write.c, \ref osx_write.c,
  29  *      - http: \ref http_recv.c, \ref http_send.c,
  30  *      - udp: \ref udp_recv.c, \ref udp_send.c,
  31  *      - dccp: \ref dccp_recv.c, \ref dccp_send.c,
  32  *      - Audio file selector: \ref afs.c, \ref aft.c, \ref mood.c,
  33  *      - Afs structures: \ref afs_table, \ref audio_file_data,
  34  *        \ref afs_info \ref afh_info,
  35  *      - Afs tables: \ref aft.c, \ref mood.c, \ref playlist.c,
  36  *        \ref attribute.c, \ref score.c,
  37  *      - The virtual streaming system: \ref vss.c, \ref chunk_queue.c.
  38  *
  39  * Lower levels:
  40  *
  41  *      - Scheduling: \ref sched.c, \ref sched.h,
  42  *      - Networking: \ref net.c,
  43  *      - File descriptors: \ref fd.c,
  44  *      - Signals: \ref signal.c,
  45  *      - Daemons: \ref daemon.c,
  46  *      - Strings: \ref string.c, \ref string.h,
  47  *      - Time: \ref time.c,
  48  *      - Spawning processes: \ref exec.c,
  49  *      - Inter process communication: \ref ipc.c,
  50  *      - Blob tables: \ref blob.c,
  51  *      - The error subssystem: \ref error.h.
  52  *      - Access control for paraslash senders: \ref acl.c, \ref acl.h.
  53  *
  54  * Low-level data structures:
  55  *
  56  *      - Doubly linked lists: \ref list.h,
  57  *      - Ring buffer: \ref ringbuffer.c, \ref ringbuffer.h,
  58  *      - Hashing: \ref hash.h, \ref sha1.h, \ref sha1.c,
  59  *      - Crypto: \ref crypt.c.
  60  *      - Forward error correction: \ref fec.c
  61  */
  62
  63 #include <signal.h>
  64 #include <dirent.h>
  65 #include <sys/time.h>
  66 #include <openssl/rc4.h>
  67 #include <osl.h>
  68
  69 #include "para.h"
  70 #include "error.h"
  71 #include "crypt.h"
  72 #include "server.cmdline.h"
  73 #include "afh.h"
  74 #include "string.h"
  75 #include "afs.h"
  76 #include "server.h"
  77 #include "vss.h"
  78 #include "config.h"
  79 #include "close_on_fork.h"
  80 #include "list.h"
  81 #include "send.h"
  82 #include "net.h"
  83 #include "daemon.h"
  84 #include "ipc.h"
  85 #include "fd.h"
  86 #include "sched.h"
  87 #include "signal.h"
  88 #include "user_list.h"
  89 #include "color.h"
  90
  91 /** Define the array of error lists needed by para_server. */
  92 INIT_SERVER_ERRLISTS;
  93
  94 /** Shut down non-authorized connections after that many seconds. */
  95 #define ALARM_TIMEOUT 10
  96
  97 /**
  98  * Pointer to shared memory area for communication between para_server
  99  * and its children. Exported to vss.c. command.c and to afs.
 100  */
 101 struct misc_meta_data *mmd;
 102
 103 /**
 104  * The configuration of para_server
 105  *
 106  * It also contains the options for the audio file selector, audio format
 107  * handler and all supported senders.
 108  */
 109 struct server_args_info conf;
 110
 111 /** A random value used in child context for authentication. */
 112 uint32_t afs_socket_cookie;
 113
 114 /** The mutex protecting the shared memory area containing the mmd struct. */
 115 int mmd_mutex;
 116
 117 /** The file containing user information (public key, permissions). */
 118 static char *user_list_file = NULL;
 119
 120
 121 /** The task responsible for server command handling. */
 122 struct server_command_task {
 123         /** TCP port on which para_server listens for connections. */
 124         int listen_fd;
 125         /** Copied from para_server's main function. */
 126         int argc;
 127         /** Argument vector passed to para_server's main function. */
 128         char **argv;
 129         /** The command task structure for scheduling. */
 130         struct task task;
 131 };
 132
 133 static int want_colors(void)
 134 {
 135         if (conf.color_arg == color_arg_no)
 136                 return 0;
 137         if (conf.color_arg == color_arg_yes)
 138                 return 1;
 139         if (conf.logfile_given)
 140                 return 0;
 141         return isatty(STDERR_FILENO);
 142 }
 143
 144 static void init_colors_or_die(void)
 145 {
 146         int ret, i;
 147
 148         if (!want_colors())
 149                 return;
 150         daemon_set_flag(DF_COLOR_LOG);
 151         daemon_set_default_log_colors();
 152         for (i = 0; i < conf.log_color_given; i++) {
 153                 ret = daemon_set_log_color(conf.log_color_arg[i]);
 154                 if (ret < 0)
 155                         exit(EXIT_FAILURE);
 156         }
 157 }
 158
 159 /*
 160  * setup shared memory area and get mutex for locking
 161  */
 162 static void init_ipc_or_die(void)
 163 {
 164         void *shm;
 165         int shmid, ret = shm_new(sizeof(struct misc_meta_data));
 166
 167         if (ret < 0)
 168                 goto err_out;
 169         shmid = ret;
 170         ret = shm_attach(shmid, ATTACH_RW, &shm);
 171         shm_destroy(shmid);
 172         if (ret < 0)
 173                 goto err_out;
 174         mmd = shm;
 175
 176         ret = mutex_new();
 177         if (ret < 0)
 178                 goto err_out;
 179         mmd_mutex = ret;
 180
 181         mmd->num_played = 0;
 182         mmd->num_commands = 0;
 183         mmd->events = 0;
 184         mmd->num_connects = 0;
 185         mmd->active_connections = 0;
 186         mmd->vss_status_flags = VSS_NEXT;
 187         mmd->new_vss_status_flags = VSS_NEXT;
 188         return;
 189 err_out:
 190         PARA_EMERG_LOG("%s\n", para_strerror(-ret));
 191         exit(EXIT_FAILURE);
 192 }
 193
 194 /**
 195  * (Re-)read the server configuration files.
 196  *
 197  * \param override Passed to gengetopt to activate the override feature.
 198  *
 199  * This function also re-opens the logfile and sets the global \a
 200  * user_list_file variable.
 201  */
 202 void parse_config_or_die(int override)
 203 {
 204         char *home = para_homedir();
 205         int ret;
 206         char *cf;
 207
 208         daemon_close_log();
 209         if (conf.config_file_given)
 210                 cf = para_strdup(conf.config_file_arg);
 211         else
 212                 cf = make_message("%s/.paraslash/server.conf", home);
 213         free(user_list_file);
 214         if (!conf.user_list_given)
 215                 user_list_file = make_message("%s/.paraslash/server.users", home);
 216         else
 217                 user_list_file = para_strdup(conf.user_list_arg);
 218         ret = file_exists(cf);
 219         if (conf.config_file_given && !ret)  {
 220                 ret = -1;
 221                 PARA_EMERG_LOG("can not read config file %s\n", cf);
 222                 goto out;
 223         }
 224         if (ret) {
 225                 int tmp = conf.daemon_given;
 226                 struct server_cmdline_parser_params params = {
 227                         .override = override,
 228                         .initialize = 0,
 229                         .check_required = 1,
 230                         .check_ambiguity = 0,
 231                         .print_errors = !conf.daemon_given
 232                 };
 233                 server_cmdline_parser_config_file(cf, &conf, &params);
 234                 conf.daemon_given = tmp;
 235         }
 236         if (conf.logfile_given) {
 237                 daemon_set_logfile(conf.logfile_arg);
 238                 daemon_open_log_or_die();
 239         }
 240         daemon_set_loglevel(conf.loglevel_arg);
 241         init_colors_or_die();
 242         daemon_set_flag(DF_LOG_PID);
 243         daemon_set_flag(DF_LOG_LL);
 244         daemon_set_flag(DF_LOG_TIME);
 245         ret = 1;
 246 out:
 247         free(cf);
 248         free(home);
 249         if (ret > 0)
 250                 return;
 251         free(user_list_file);
 252         user_list_file = NULL;
 253         exit(EXIT_FAILURE);
 254 }
 255
 256 static void signal_pre_select(struct sched *s, struct task *t)
 257 {
 258         struct signal_task *st = container_of(t, struct signal_task, task);
 259         para_fd_set(st->fd, &s->rfds, &s->max_fileno);
 260 }
 261
 262 /*
 263  * called when server gets SIGHUP or when client invokes hup command.
 264  */
 265 static void handle_sighup(void)
 266 {
 267         PARA_NOTICE_LOG("SIGHUP\n");
 268         parse_config_or_die(1); /* reopens log */
 269         init_user_list(user_list_file); /* reload user list */
 270         if (mmd->afs_pid)
 271                 kill(mmd->afs_pid, SIGHUP);
 272 }
 273
 274 static void signal_post_select(struct sched *s, struct task *t)
 275 {
 276         struct signal_task *st = container_of(t, struct signal_task, task);
 277
 278         if (!FD_ISSET(st->fd, &s->rfds))
 279                 return;
 280
 281         st->signum = para_next_signal();
 282         switch (st->signum) {
 283         case SIGHUP:
 284                 handle_sighup();
 285                 break;
 286         case SIGCHLD:
 287                 for (;;) {
 288                         pid_t pid;
 289                         int ret = para_reap_child(&pid);
 290                         if (ret <= 0)
 291                                 break;
 292                         if (pid != mmd->afs_pid)
 293                                 continue;
 294                         PARA_EMERG_LOG("fatal: afs died\n");
 295                         kill(0, SIGTERM);
 296                         goto cleanup;
 297                 }
 298                 break;
 299         /* die on sigint/sigterm. Kill all children too. */
 300         case SIGINT:
 301         case SIGTERM:
 302                 PARA_EMERG_LOG("terminating on signal %d\n", st->signum);
 303                 kill(0, SIGTERM);
 304                 /*
 305                  * We must wait for afs because afs catches SIGINT/SIGTERM.
 306                  * Before reacting to the signal, afs might want to use the
 307                  * shared memory area and the mmd mutex.  If we destroy this
 308                  * mutex too early and afs tries to lock the shared memory
 309                  * area, the call to mutex_lock() will fail and terminate the
 310                  * afs process. This leads to dirty osl tables.
 311                  *
 312                  * There's no such problem with the other children of the
 313                  * server process (the command handlers) as these reset their
 314                  * SIGINT/SIGTERM handlers to the default action, i.e.  these
 315                  * processes get killed immediately by the above kill().
 316                  */
 317                 PARA_INFO_LOG("waiting for afs (pid %d) to die\n",
 318                         (int)mmd->afs_pid);
 319                 waitpid(mmd->afs_pid, NULL, 0);
 320 cleanup:
 321                 free(mmd->afd.afhi.chunk_table);
 322                 close_listed_fds();
 323                 mutex_destroy(mmd_mutex);
 324                 shm_detach(mmd);
 325                 exit(EXIT_FAILURE);
 326         }
 327 }
 328
 329 static void init_signal_task(void)
 330 {
 331         static struct signal_task signal_task_struct,
 332                 *st = &signal_task_struct;
 333
 334         st->task.pre_select = signal_pre_select;
 335         st->task.post_select = signal_post_select;
 336         sprintf(st->task.status, "signal task");
 337
 338         PARA_NOTICE_LOG("setting up signal handling\n");
 339         st->fd = para_signal_init(); /* always successful */
 340         para_install_sighandler(SIGINT);
 341         para_install_sighandler(SIGTERM);
 342         para_install_sighandler(SIGHUP);
 343         para_install_sighandler(SIGCHLD);
 344         para_sigaction(SIGPIPE, SIG_IGN);
 345         add_close_on_fork_list(st->fd);
 346         register_task(&st->task);
 347 }
 348
 349 static void command_pre_select(struct sched *s, struct task *t)
 350 {
 351         struct server_command_task *sct = container_of(t, struct server_command_task, task);
 352         para_fd_set(sct->listen_fd, &s->rfds, &s->max_fileno);
 353 }
 354
 355 static void command_post_select(struct sched *s, struct task *t)
 356 {
 357         struct server_command_task *sct = container_of(t, struct server_command_task, task);
 358
 359         int new_fd, ret, i;
 360         char *peer_name;
 361         pid_t child_pid;
 362         uint32_t *chunk_table;
 363
 364         if (!FD_ISSET(sct->listen_fd, &s->rfds))
 365                 return;
 366         ret = para_accept(sct->listen_fd, NULL, 0);
 367         if (ret < 0)
 368                 goto out;
 369         new_fd = ret;
 370         peer_name = remote_name(new_fd);
 371         PARA_INFO_LOG("got connection from %s, forking\n", peer_name);
 372         mmd->num_connects++;
 373         mmd->active_connections++;
 374         /*
 375          * The chunk table is a pointer located in the mmd struct that points
 376          * to dynamically allocated memory, i.e. it must be freed by the parent
 377          * and the child. However, as the mmd struct is in a shared memory
 378          * area, there's no guarantee that after the fork this pointer is still
 379          * valid in child context. As it is not used in the child anyway, we
 380          * save it to a local variable before the fork and free the memory via
 381          * that copy in the child directly after the fork.
 382          */
 383         chunk_table = mmd->afd.afhi.chunk_table;
 384         child_pid = fork();
 385         if (child_pid < 0) {
 386                 ret = -ERRNO_TO_PARA_ERROR(errno);
 387                 goto out;
 388         }
 389         if (child_pid) {
 390                 close(new_fd);
 391                 /* parent keeps accepting connections */
 392                 return;
 393         }
 394         /* mmd might already have changed at this point */
 395         free(chunk_table);
 396         alarm(ALARM_TIMEOUT);
 397         close_listed_fds();
 398         para_signal_shutdown();
 399         /*
 400          * put info on who we are serving into argv[0] to make
 401          * client ip visible in top/ps
 402          */
 403         for (i = sct->argc - 1; i >= 0; i--)
 404                 memset(sct->argv[i], 0, strlen(sct->argv[i]));
 405         sprintf(sct->argv[0], "para_server (serving %s)", peer_name);
 406         return handle_connect(new_fd, peer_name);
 407 out:
 408         if (ret < 0)
 409                 PARA_CRIT_LOG("%s\n", para_strerror(-ret));
 410 }
 411
 412 static void init_server_command_task(int argc, char **argv)
 413 {
 414         int ret;
 415         static struct server_command_task server_command_task_struct,
 416                 *sct = &server_command_task_struct;
 417
 418         PARA_NOTICE_LOG("initializing tcp command socket\n");
 419         sct->task.pre_select = command_pre_select;
 420         sct->task.post_select = command_post_select;
 421         sct->argc = argc;
 422         sct->argv = argv;
 423         ret = para_listen(AF_UNSPEC, IPPROTO_TCP, conf.port_arg);
 424         if (ret < 0)
 425                 goto err;
 426         sct->listen_fd = ret;
 427         ret = mark_fd_nonblocking(sct->listen_fd);
 428         if (ret < 0)
 429                 goto err;
 430         add_close_on_fork_list(sct->listen_fd); /* child doesn't need the listener */
 431         register_task(&sct->task);
 432         return;
 433 err:
 434         PARA_EMERG_LOG("%s\n", para_strerror(-ret));
 435         exit(EXIT_FAILURE);
 436 }
 437
 438 static int init_afs(void)
 439 {
 440         int ret, afs_server_socket[2];
 441
 442         ret = socketpair(PF_UNIX, SOCK_DGRAM, 0, afs_server_socket);
 443         if (ret < 0)
 444                 exit(EXIT_FAILURE);
 445         get_random_bytes_or_die((unsigned char *)&afs_socket_cookie,
 446                 sizeof(afs_socket_cookie));
 447         mmd->afs_pid = fork();
 448         if (mmd->afs_pid < 0)
 449                 exit(EXIT_FAILURE);
 450         if (!mmd->afs_pid) { /* child (afs) */
 451                 close(afs_server_socket[0]);
 452                 afs_init(afs_socket_cookie, afs_server_socket[1]);
 453         }
 454         close(afs_server_socket[1]);
 455         ret = mark_fd_nonblocking(afs_server_socket[0]);
 456         if (ret < 0)
 457                 exit(EXIT_FAILURE);
 458         add_close_on_fork_list(afs_server_socket[0]);
 459         PARA_INFO_LOG("afs_socket: %d, afs_socket_cookie: %u\n",
 460                 afs_server_socket[0], (unsigned) afs_socket_cookie);
 461         return afs_server_socket[0];
 462 }
 463
 464 __noreturn static void tmp_sigchld_handler(__a_unused int s)
 465 {
 466         PARA_EMERG_LOG("caught early SIGCHLD\n");
 467         exit(EXIT_FAILURE);
 468 }
 469
 470 static void server_init(int argc, char **argv)
 471 {
 472         struct server_cmdline_parser_params params = {
 473                 .override = 0,
 474                 .initialize = 1,
 475                 .check_required = 0,
 476                 .check_ambiguity = 0,
 477                 .print_errors = 1
 478         };
 479         int afs_socket;
 480
 481         valid_fd_012();
 482         init_random_seed_or_die();
 483         /* parse command line options */
 484         server_cmdline_parser_ext(argc, argv, &conf, &params);
 485         HANDLE_VERSION_FLAG("server", conf);
 486         drop_privileges_or_die(conf.user_arg, conf.group_arg);
 487         /* parse config file, open log and set defaults */
 488         parse_config_or_die(0);
 489         log_welcome("para_server");
 490         init_ipc_or_die(); /* init mmd struct and mmd->lock */
 491         /* make sure, the global now pointer is uptodate */
 492         gettimeofday(now, NULL);
 493         server_uptime(UPTIME_SET); /* reset server uptime */
 494         init_user_list(user_list_file);
 495         /* become daemon */
 496         if (conf.daemon_given)
 497                 daemonize();
 498         PARA_NOTICE_LOG("initializing audio format handlers\n");
 499         afh_init();
 500
 501         /*
 502          * Although afs uses its own signal handling we must ignore SIGUSR1
 503          * _before_ the afs child process gets born by init_afs() below.  It's
 504          * racy to do this in the child because the parent might send SIGUSR1
 505          * before the child gets a chance to ignore this signal -- only the
 506          * good die young.
 507          */
 508         para_sigaction(SIGUSR1, SIG_IGN);
 509         /*
 510          * We have to install a SIGCHLD handler before the afs process is being
 511          * forked off. Otherwise, para_server does not notice if afs dies before
 512          * the SIGCHLD handler has been installed by init_signal_task() below.
 513          */
 514         para_sigaction(SIGCHLD, tmp_sigchld_handler);
 515         PARA_NOTICE_LOG("initializing the audio file selector\n");
 516         afs_socket = init_afs();
 517         init_signal_task();
 518         PARA_NOTICE_LOG("initializing virtual streaming system\n");
 519         init_vss_task(afs_socket);
 520         init_server_command_task(argc, argv);
 521         PARA_NOTICE_LOG("server init complete\n");
 522 }
 523
 524 static void status_refresh(void)
 525 {
 526         static int prev_uptime = -1, prev_events = -1;
 527         int uptime = server_uptime(UPTIME_GET), ret = 1;
 528
 529         if (prev_events != mmd->events)
 530                 goto out;
 531         if (mmd->new_vss_status_flags != mmd->vss_status_flags)
 532                 goto out_inc_events;
 533         if (uptime / 60 != prev_uptime / 60)
 534                 goto out_inc_events;
 535         return;
 536 out_inc_events:
 537         mmd->events++;
 538 out:
 539         prev_uptime = uptime;
 540         prev_events = mmd->events;
 541         mmd->vss_status_flags = mmd->new_vss_status_flags;
 542         if (ret) {
 543                 PARA_DEBUG_LOG("%d events, forcing status update\n",
 544                         mmd->events);
 545                 killpg(0, SIGUSR1);
 546         }
 547 }
 548
 549 static int server_select(int max_fileno, fd_set *readfds, fd_set *writefds,
 550                 struct timeval *timeout_tv)
 551 {
 552         int ret;
 553
 554         status_refresh();
 555         mutex_unlock(mmd_mutex);
 556         ret = para_select(max_fileno + 1, readfds, writefds, timeout_tv);
 557         mutex_lock(mmd_mutex);
 558         return ret;
 559 }
 560
 561 /**
 562  * The main function of para_server.
 563  *
 564  * \param argc Usual argument count.
 565  * \param argv Usual argument vector.
 566  *
 567  * \return EXIT_SUCCESS or EXIT_FAILURE.
 568  */
 569 int main(int argc, char *argv[])
 570 {
 571         int ret;
 572         static struct sched s = {
 573                 .default_timeout = {
 574                         .tv_sec = 1,
 575                         .tv_usec = 0
 576                 },
 577                 .select_function = server_select
 578         };
 579         server_init(argc, argv);
 580         mutex_lock(mmd_mutex);
 581         ret = schedule(&s);
 582         if (ret < 0) {
 583                 PARA_EMERG_LOG("%s\n", para_strerror(-ret));
 584                 exit(EXIT_FAILURE);
 585         }
 586         exit(EXIT_SUCCESS);
 587 }