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 fsck.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  *      - The object storage layer: \ref osl.c,
  51  *      - Blob tables: \ref blob.c,
  52  *      - The error subssystem: \ref error.h.
  53  *      - Access control for paraslash senders: \ref acl.c, \ref acl.h.
  54  *
  55  * Low-level data structures:
  56  *
  57  *      - Doubly linked lists: \ref list.h,
  58  *      - Red-black trees: \ref rbtree.h, \ref rbtree.c,
  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  *
  63  */
  64
  65 #include <signal.h>
  66 #include <dirent.h>
  67 #include <sys/time.h>
  68
  69 #include "para.h"
  70 #include "error.h"
  71 #include "server.cmdline.h"
  72 #include "afh.h"
  73 #include "string.h"
  74 #include "afs.h"
  75 #include "server.h"
  76 #include "vss.h"
  77 #include "config.h"
  78 #include "close_on_fork.h"
  79 #include "list.h"
  80 #include "send.h"
  81 #include "net.h"
  82 #include "daemon.h"
  83 #include "ipc.h"
  84 #include "fd.h"
  85 #include "sched.h"
  86 #include "signal.h"
  87 #include "user_list.h"
  88 #include "color.h"
  89
  90 /** Define the array of error lists needed by para_server. */
  91 INIT_SERVER_ERRLISTS;
  92
  93 /** Shut down non-authorized connections after that many seconds. */
  94 #define ALARM_TIMEOUT 10
  95
  96 /**
  97  * Pointer to shared memory area for communication between para_server
  98  * and its children. Exported to vss.c. command.c and to afs.
  99  */
 100 struct misc_meta_data *mmd;
 101
 102 /**
 103  * The configuration of para_server
 104  *
 105  * It also contains the options for the audio file selector, audio format
 106  * handler and all supported senders.
 107  */
 108 struct server_args_info conf;
 109
 110 /** A random value used in child context for authentication. */
 111 uint32_t afs_socket_cookie;
 112
 113 /** The mutex protecting the shared memory area containing the mmd struct. */
 114 int mmd_mutex;
 115
 116 /** The file containing user information (public key, permissions). */
 117 static char *user_list_file = NULL;
 118
 119
 120 /** The task responsible for server command handling. */
 121 struct server_command_task {
 122         /** TCP port on which para_server listens for connections. */
 123         int listen_fd;
 124         /** Copied from para_server's main function. */
 125         int argc;
 126         /** Argument vector passed to para_server's main function. */
 127         char **argv;
 128         /** The command task structure for scheduling. */
 129         struct task task;
 130 };
 131
 132 static int want_colors(void)
 133 {
 134         if (conf.color_arg == color_arg_no)
 135                 return 0;
 136         if (conf.color_arg == color_arg_yes)
 137                 return 1;
 138         if (conf.logfile_given)
 139                 return 0;
 140         return isatty(STDERR_FILENO);
 141 }
 142
 143 static void init_colors_or_die(void)
 144 {
 145         int ret, i;
 146
 147         if (!want_colors())
 148                 return;
 149         daemon_set_flag(DF_COLOR_LOG);
 150         daemon_set_default_log_colors();
 151         for (i = 0; i < conf.log_color_given; i++) {
 152                 ret = daemon_set_log_color(conf.log_color_arg[i]);
 153                 if (ret < 0)
 154                         exit(EXIT_FAILURE);
 155         }
 156 }
 157
 158 /*
 159  * setup shared memory area and get mutex for locking
 160  */
 161 static void init_ipc_or_die(void)
 162 {
 163         void *shm;
 164         int shmid, ret = shm_new(sizeof(struct misc_meta_data));
 165
 166         if (ret < 0)
 167                 goto err_out;
 168         shmid = ret;
 169         ret = shm_attach(shmid, ATTACH_RW, &shm);
 170         shm_destroy(shmid);
 171         if (ret < 0)
 172                 goto err_out;
 173         mmd = shm;
 174
 175         ret = mutex_new();
 176         if (ret < 0)
 177                 goto err_out;
 178         mmd_mutex = ret;
 179
 180         mmd->num_played = 0;
 181         mmd->num_commands = 0;
 182         mmd->events = 0;
 183         mmd->num_connects = 0;
 184         mmd->active_connections = 0;
 185         mmd->vss_status_flags = VSS_NEXT;
 186         mmd->new_vss_status_flags = VSS_NEXT;
 187         return;
 188 err_out:
 189         PARA_EMERG_LOG("%s\n", para_strerror(-ret));
 190         exit(EXIT_FAILURE);
 191 }
 192
 193 /**
 194  * (Re-)read the server configuration files.
 195  *
 196  * \param override Passed to gengetopt to activate the override feature.
 197  *
 198  * This function also re-opens the logfile and sets the global \a
 199  * user_list_file variable.
 200  */
 201 void parse_config_or_die(int override)
 202 {
 203         char *home = para_homedir();
 204         int ret;
 205         char *cf;
 206
 207         daemon_close_log();
 208         if (conf.config_file_given)
 209                 cf = para_strdup(conf.config_file_arg);
 210         else
 211                 cf = make_message("%s/.paraslash/server.conf", home);
 212         free(user_list_file);
 213         if (!conf.user_list_given)
 214                 user_list_file = make_message("%s/.paraslash/server.users", home);
 215         else
 216                 user_list_file = para_strdup(conf.user_list_arg);
 217         ret = file_exists(cf);
 218         if (conf.config_file_given && !ret)  {
 219                 ret = -1;
 220                 PARA_EMERG_LOG("can not read config file %s\n", cf);
 221                 goto out;
 222         }
 223         if (ret) {
 224                 int tmp = conf.daemon_given;
 225                 struct server_cmdline_parser_params params = {
 226                         .override = override,
 227                         .initialize = 0,
 228                         .check_required = 1,
 229                         .check_ambiguity = 0,
 230                         .print_errors = !conf.daemon_given
 231                 };
 232                 server_cmdline_parser_config_file(cf, &conf, &params);
 233                 conf.daemon_given = tmp;
 234         }
 235         if (conf.logfile_given) {
 236                 daemon_set_logfile(conf.logfile_arg);
 237                 daemon_open_log_or_die();
 238         }
 239         daemon_set_loglevel(conf.loglevel_arg);
 240         init_colors_or_die();
 241         daemon_set_flag(DF_LOG_PID);
 242         daemon_set_flag(DF_LOG_LL);
 243         daemon_set_flag(DF_LOG_TIME);
 244         ret = 1;
 245 out:
 246         free(cf);
 247         free(home);
 248         if (ret > 0)
 249                 return;
 250         free(user_list_file);
 251         user_list_file = NULL;
 252         exit(EXIT_FAILURE);
 253 }
 254
 255 static void signal_pre_select(struct sched *s, struct task *t)
 256 {
 257         struct signal_task *st = container_of(t, struct signal_task, task);
 258         para_fd_set(st->fd, &s->rfds, &s->max_fileno);
 259 }
 260
 261 /*
 262  * called when server gets SIGHUP or when client invokes hup command.
 263  */
 264 static void handle_sighup(void)
 265 {
 266         PARA_NOTICE_LOG("SIGHUP\n");
 267         parse_config_or_die(1); /* reopens log */
 268         init_user_list(user_list_file); /* reload user list */
 269         if (mmd->afs_pid)
 270                 kill(mmd->afs_pid, SIGHUP);
 271 }
 272
 273 static void signal_post_select(struct sched *s, struct task *t)
 274 {
 275         struct signal_task *st = container_of(t, struct signal_task, task);
 276
 277         if (!FD_ISSET(st->fd, &s->rfds))
 278                 return;
 279
 280         st->signum = para_next_signal();
 281         switch (st->signum) {
 282         case SIGHUP:
 283                 handle_sighup();
 284                 break;
 285         case SIGCHLD:
 286                 for (;;) {
 287                         pid_t pid;
 288                         int ret = para_reap_child(&pid);
 289                         if (ret <= 0)
 290                                 break;
 291                         if (pid != mmd->afs_pid)
 292                                 continue;
 293                         PARA_EMERG_LOG("fatal: afs died\n");
 294                         kill(0, SIGTERM);
 295                         goto cleanup;
 296                 }
 297                 break;
 298         /* die on sigint/sigterm. Kill all children too. */
 299         case SIGINT:
 300         case SIGTERM:
 301                 PARA_EMERG_LOG("terminating on signal %d\n", st->signum);
 302                 kill(0, SIGTERM);
 303                 /*
 304                  * We must wait for afs because afs catches SIGINT/SIGTERM.
 305                  * Before reacting to the signal, afs might want to use the
 306                  * shared memory area and the mmd mutex.  If we destroy this
 307                  * mutex too early and afs tries to lock the shared memory
 308                  * area, the call to mutex_lock() will fail and terminate the
 309                  * afs process. This leads to dirty osl tables.
 310                  *
 311                  * There's no such problem with the other children of the
 312                  * server process (the command handlers) as these reset their
 313                  * SIGINT/SIGTERM handlers to the default action, i.e.  these
 314                  * processes get killed immediately by the above kill().
 315                  */
 316                 PARA_INFO_LOG("waiting for afs (pid %d) to die\n",
 317                         (int)mmd->afs_pid);
 318                 waitpid(mmd->afs_pid, NULL, 0);
 319 cleanup:
 320                 free(mmd->afd.afhi.chunk_table);
 321                 free(mmd->afd.afhi.info_string);
 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         st->fd = para_signal_init(); /* always successful */
 339
 340         PARA_NOTICE_LOG("setting up signal handlers\n");
 341         if (para_install_sighandler(SIGINT) < 0)
 342                 goto err;
 343         if (para_install_sighandler(SIGTERM) < 0)
 344                 goto err;
 345         if (para_install_sighandler(SIGHUP) < 0)
 346                 goto err;
 347         if (para_install_sighandler(SIGCHLD) < 0)
 348                 goto err;
 349         if (signal(SIGPIPE, SIG_IGN) == SIG_ERR)
 350                 goto err;
 351         add_close_on_fork_list(st->fd);
 352         register_task(&st->task);
 353         return;
 354 err:
 355         PARA_EMERG_LOG("could not install signal handlers\n");
 356         exit(EXIT_FAILURE);
 357 }
 358
 359 static void command_pre_select(struct sched *s, struct task *t)
 360 {
 361         struct server_command_task *sct = container_of(t, struct server_command_task, task);
 362         para_fd_set(sct->listen_fd, &s->rfds, &s->max_fileno);
 363 }
 364
 365 static void command_post_select(struct sched *s, struct task *t)
 366 {
 367         struct server_command_task *sct = container_of(t, struct server_command_task, task);
 368
 369         int new_fd, ret, i;
 370         char *peer_name;
 371         pid_t child_pid;
 372         uint32_t *chunk_table;
 373         char *info_string;
 374
 375         if (!FD_ISSET(sct->listen_fd, &s->rfds))
 376                 return;
 377         ret = para_accept(sct->listen_fd, NULL, 0);
 378         if (ret < 0)
 379                 goto out;
 380         new_fd = ret;
 381         peer_name = remote_name(new_fd);
 382         PARA_INFO_LOG("got connection from %s, forking\n", peer_name);
 383         mmd->num_connects++;
 384         mmd->active_connections++;
 385         random();
 386         /* The chunk table and the info_string are pointers located in the
 387          * mmd struct that point to dynamically allocated memory that must be
 388          * freed by the parent and the child. However, as the mmd struct is in
 389          * a shared memory area, there's no guarantee that after the fork these
 390          * pointers are still valid in child context. As these two pointers are
 391          * not used in the child anyway, we save them to local variables and
 392          * free the memory via that copy in the child.
 393          */
 394         info_string = mmd->afd.afhi.info_string;
 395         chunk_table = mmd->afd.afhi.chunk_table;
 396         child_pid = fork();
 397         if (child_pid < 0) {
 398                 ret = -ERRNO_TO_PARA_ERROR(errno);
 399                 goto out;
 400         }
 401         if (child_pid) {
 402                 close(new_fd);
 403                 /* parent keeps accepting connections */
 404                 return;
 405         }
 406         /* mmd might already have changed at this point */
 407         free(info_string);
 408         free(chunk_table);
 409         alarm(ALARM_TIMEOUT);
 410         close_listed_fds();
 411         para_signal_shutdown();
 412         /*
 413          * put info on who we are serving into argv[0] to make
 414          * client ip visible in top/ps
 415          */
 416         for (i = sct->argc - 1; i >= 0; i--)
 417                 memset(sct->argv[i], 0, strlen(sct->argv[i]));
 418         sprintf(sct->argv[0], "para_server (serving %s)", peer_name);
 419         return handle_connect(new_fd, peer_name);
 420 out:
 421         if (ret < 0)
 422                 PARA_CRIT_LOG("%s\n", para_strerror(-ret));
 423 }
 424
 425 static void init_server_command_task(int argc, char **argv)
 426 {
 427         int ret;
 428         static struct server_command_task server_command_task_struct,
 429                 *sct = &server_command_task_struct;
 430
 431         PARA_NOTICE_LOG("initializing tcp command socket\n");
 432         sct->task.pre_select = command_pre_select;
 433         sct->task.post_select = command_post_select;
 434         sct->argc = argc;
 435         sct->argv = argv;
 436         ret = para_listen(AF_UNSPEC, IPPROTO_TCP, conf.port_arg);
 437         if (ret < 0)
 438                 goto err;
 439         sct->listen_fd = ret;
 440         ret = mark_fd_nonblocking(sct->listen_fd);
 441         if (ret < 0)
 442                 goto err;
 443         add_close_on_fork_list(sct->listen_fd); /* child doesn't need the listener */
 444         register_task(&sct->task);
 445         return;
 446 err:
 447         PARA_EMERG_LOG("%s\n", para_strerror(-ret));
 448         exit(EXIT_FAILURE);
 449 }
 450
 451 static void init_random_seed(void)
 452 {
 453         unsigned int seed;
 454         int fd, ret = para_open("/dev/urandom", O_RDONLY, 0);
 455
 456         if (ret < 0)
 457                 goto err;
 458         fd = ret;
 459         ret = read(fd, &seed, sizeof(seed));
 460         if (ret < 0) {
 461                 ret = -ERRNO_TO_PARA_ERROR(errno);
 462                 goto out;
 463         }
 464         if (ret != sizeof(seed)) {
 465                 ret = -ERRNO_TO_PARA_ERROR(EIO);
 466                 goto out;
 467         }
 468         srandom(seed);
 469         ret = 1;
 470 out:
 471         close(fd);
 472         if (ret >= 0)
 473                 return;
 474 err:
 475         PARA_EMERG_LOG("can not seed pseudo random number generator: %s\n",
 476                 para_strerror(-ret));
 477         exit(EXIT_FAILURE);
 478 }
 479
 480 static int init_afs(void)
 481 {
 482         int ret, afs_server_socket[2];
 483
 484         ret = socketpair(PF_UNIX, SOCK_DGRAM, 0, afs_server_socket);
 485         if (ret < 0)
 486                 exit(EXIT_FAILURE);
 487         afs_socket_cookie = para_random((uint32_t)-1);
 488         mmd->afs_pid = fork();
 489         if (mmd->afs_pid < 0)
 490                 exit(EXIT_FAILURE);
 491         if (!mmd->afs_pid) { /* child (afs) */
 492                 close(afs_server_socket[0]);
 493                 afs_init(afs_socket_cookie, afs_server_socket[1]);
 494         }
 495         close(afs_server_socket[1]);
 496         ret = mark_fd_nonblocking(afs_server_socket[0]);
 497         if (ret < 0)
 498                 exit(EXIT_FAILURE);
 499         add_close_on_fork_list(afs_server_socket[0]);
 500         PARA_INFO_LOG("afs_socket: %d, afs_socket_cookie: %u\n",
 501                 afs_server_socket[0], (unsigned) afs_socket_cookie);
 502         return afs_server_socket[0];
 503 }
 504
 505 __noreturn static void tmp_sigchld_handler(__a_unused int s)
 506 {
 507         PARA_EMERG_LOG("caught early SIGCHLD\n");
 508         exit(EXIT_FAILURE);
 509 }
 510
 511 static void server_init(int argc, char **argv)
 512 {
 513         struct server_cmdline_parser_params params = {
 514                 .override = 0,
 515                 .initialize = 1,
 516                 .check_required = 0,
 517                 .check_ambiguity = 0,
 518                 .print_errors = 1
 519         };
 520         int afs_socket;
 521
 522         valid_fd_012();
 523         init_random_seed();
 524         /* parse command line options */
 525         server_cmdline_parser_ext(argc, argv, &conf, &params);
 526         HANDLE_VERSION_FLAG("server", conf);
 527         drop_privileges_or_die(conf.user_arg, conf.group_arg);
 528         /* parse config file, open log and set defaults */
 529         parse_config_or_die(0);
 530         log_welcome("para_server");
 531         init_ipc_or_die(); /* init mmd struct and mmd->lock */
 532         /* make sure, the global now pointer is uptodate */
 533         gettimeofday(now, NULL);
 534         server_uptime(UPTIME_SET); /* reset server uptime */
 535         init_user_list(user_list_file);
 536         /* become daemon */
 537         if (conf.daemon_given)
 538                 daemonize();
 539         PARA_NOTICE_LOG("initializing audio format handlers\n");
 540         afh_init();
 541
 542         /*
 543          * Although afs uses its own signal handling we must ignore SIGUSR1
 544          * _before_ the afs child process gets born by init_afs() below.  It's
 545          * racy to do this in the child because the parent might send SIGUSR1
 546          * before the child gets a chance to ignore this signal -- only the
 547          * good die young.
 548          */
 549         if (signal(SIGUSR1, SIG_IGN) == SIG_ERR) {
 550                 PARA_EMERG_LOG("failed to ignore SIGUSR1\n");
 551                 exit(EXIT_FAILURE);
 552         }
 553         /*
 554          * We have to install a SIGCHLD handler before the afs process is being
 555          * forked off. Otherwise, para_server does not notice if afs dies before
 556          * the SIGCHLD handler has been installed by init_signal_task() below.
 557          */
 558         if (signal(SIGCHLD, tmp_sigchld_handler) == SIG_ERR) {
 559                 PARA_EMERG_LOG("failed to install temporary SIGCHLD handler\n");
 560                 exit(EXIT_FAILURE);
 561         }
 562         PARA_NOTICE_LOG("initializing the audio file selector\n");
 563         afs_socket = init_afs();
 564         init_signal_task();
 565         PARA_NOTICE_LOG("initializing virtual streaming system\n");
 566         init_vss_task(afs_socket);
 567         init_server_command_task(argc, argv);
 568         PARA_NOTICE_LOG("server init complete\n");
 569 }
 570
 571 static void status_refresh(void)
 572 {
 573         static int prev_uptime = -1, prev_events = -1;
 574         int uptime = server_uptime(UPTIME_GET), ret = 1;
 575
 576         if (prev_events != mmd->events)
 577                 goto out;
 578         if (mmd->new_vss_status_flags != mmd->vss_status_flags)
 579                 goto out_inc_events;
 580         if (uptime / 60 != prev_uptime / 60)
 581                 goto out_inc_events;
 582         return;
 583 out_inc_events:
 584         mmd->events++;
 585 out:
 586         prev_uptime = uptime;
 587         prev_events = mmd->events;
 588         mmd->vss_status_flags = mmd->new_vss_status_flags;
 589         if (ret) {
 590                 PARA_DEBUG_LOG("%d events, forcing status update\n",
 591                         mmd->events);
 592                 killpg(0, SIGUSR1);
 593         }
 594 }
 595
 596 static int server_select(int max_fileno, fd_set *readfds, fd_set *writefds,
 597                 struct timeval *timeout_tv)
 598 {
 599         int ret;
 600
 601         status_refresh();
 602         mutex_unlock(mmd_mutex);
 603         ret = para_select(max_fileno + 1, readfds, writefds, timeout_tv);
 604         mutex_lock(mmd_mutex);
 605         return ret;
 606 }
 607
 608 /**
 609  * The main function of para_server.
 610  *
 611  * \param argc Usual argument count.
 612  * \param argv Usual argument vector.
 613  *
 614  * \return EXIT_SUCCESS or EXIT_FAILURE.
 615  */
 616 int main(int argc, char *argv[])
 617 {
 618         int ret;
 619         static struct sched s = {
 620                 .default_timeout = {
 621                         .tv_sec = 1,
 622                         .tv_usec = 0
 623                 },
 624                 .select_function = server_select
 625         };
 626         server_init(argc, argv);
 627         mutex_lock(mmd_mutex);
 628         ret = schedule(&s);
 629         if (ret < 0) {
 630                 PARA_EMERG_LOG("%s\n", para_strerror(-ret));
 631                 exit(EXIT_FAILURE);
 632         }
 633         exit(EXIT_SUCCESS);
 634 }