server.c

   1 /*
   2  * Copyright (C) 1997-2011 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, \ref spx_afh.c
  27  *      - Decoders: \ref mp3dec_filter.c, \ref oggdec_filter.c,
  28  *        \ref aacdec_filter.c, \ref wmadec_filter.c, spxdec_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  *      - Internal crypto API: \ref crypt.h.
  56  *
  57  * Low-level data structures:
  58  *
  59  *      - Doubly linked lists: \ref list.h,
  60  *      - Ring buffer: \ref ringbuffer.c, \ref ringbuffer.h,
  61  *      - openssl: \ref crypt.c
  62  *      - libgcrypt: \ref gcrypt.c
  63  *      - Forward error correction: \ref fec.c.
  64  */
  65
  66 #include <signal.h>
  67 #include <sys/time.h>
  68 #include <regex.h>
  69 #include <osl.h>
  70 #include <stdbool.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 "list.h"
  81 #include "send.h"
  82 #include "sched.h"
  83 #include "vss.h"
  84 #include "config.h"
  85 #include "close_on_fork.h"
  86 #include "net.h"
  87 #include "daemon.h"
  88 #include "ipc.h"
  89 #include "fd.h"
  90 #include "signal.h"
  91 #include "user_list.h"
  92 #include "color.h"
  93 #include "version.h"
  94
  95 __printf_2_3 void (*para_log)(int, const char*, ...) = daemon_log;
  96
  97 /** Define the array of error lists needed by para_server. */
  98 INIT_SERVER_ERRLISTS;
  99
 100 /** Shut down non-authorized connections after that many seconds. */
 101 #define ALARM_TIMEOUT 10
 102
 103 /**
 104  * Pointer to shared memory area for communication between para_server
 105  * and its children. Exported to vss.c. command.c and to afs.
 106  */
 107 struct misc_meta_data *mmd;
 108
 109 /**
 110  * The configuration of para_server
 111  *
 112  * It also contains the options for the audio file selector, audio format
 113  * handler and all supported senders.
 114  */
 115 struct server_args_info conf;
 116
 117 /** A random value used in child context for authentication. */
 118 uint32_t afs_socket_cookie;
 119
 120 /** The mutex protecting the shared memory area containing the mmd struct. */
 121 int mmd_mutex;
 122
 123 /** The file containing user information (public key, permissions). */
 124 static char *user_list_file = NULL;
 125
 126 static struct sched sched;
 127
 128 /** The task responsible for server command handling. */
 129 struct server_command_task {
 130         /** TCP port on which para_server listens for connections. */
 131         int listen_fd;
 132         /** Copied from para_server's main function. */
 133         int argc;
 134         /** Argument vector passed to para_server's main function. */
 135         char **argv;
 136         /** The command task structure for scheduling. */
 137         struct task task;
 138 };
 139
 140 static int want_colors(void)
 141 {
 142         if (conf.color_arg == color_arg_no)
 143                 return 0;
 144         if (conf.color_arg == color_arg_yes)
 145                 return 1;
 146         if (conf.logfile_given)
 147                 return 0;
 148         return isatty(STDERR_FILENO);
 149 }
 150
 151 static void init_colors_or_die(void)
 152 {
 153         int i;
 154
 155         if (!want_colors())
 156                 return;
 157         daemon_set_flag(DF_COLOR_LOG);
 158         daemon_set_default_log_colors();
 159         for (i = 0; i < conf.log_color_given; i++)
 160                 daemon_set_log_color_or_die(conf.log_color_arg[i]);
 161 }
 162
 163 /*
 164  * setup shared memory area and get mutex for locking
 165  */
 166 static void init_ipc_or_die(void)
 167 {
 168         void *shm;
 169         int shmid, ret = shm_new(sizeof(struct misc_meta_data));
 170
 171         if (ret < 0)
 172                 goto err_out;
 173         shmid = ret;
 174         ret = shm_attach(shmid, ATTACH_RW, &shm);
 175         shm_destroy(shmid);
 176         if (ret < 0)
 177                 goto err_out;
 178         mmd = shm;
 179
 180         ret = mutex_new();
 181         if (ret < 0)
 182                 goto err_out;
 183         mmd_mutex = ret;
 184
 185         mmd->num_played = 0;
 186         mmd->num_commands = 0;
 187         mmd->events = 0;
 188         mmd->num_connects = 0;
 189         mmd->active_connections = 0;
 190         mmd->vss_status_flags = VSS_NEXT;
 191         mmd->new_vss_status_flags = VSS_NEXT;
 192         return;
 193 err_out:
 194         PARA_EMERG_LOG("%s\n", para_strerror(-ret));
 195         exit(EXIT_FAILURE);
 196 }
 197
 198 /**
 199  * (Re-)read the server configuration files.
 200  *
 201  * \param override Passed to gengetopt to activate the override feature.
 202  *
 203  * This function also re-opens the logfile and sets the global \a
 204  * user_list_file variable.
 205  */
 206 void parse_config_or_die(int override)
 207 {
 208         char *home = para_homedir();
 209         int ret;
 210         char *cf;
 211
 212         daemon_close_log();
 213         if (conf.config_file_given)
 214                 cf = para_strdup(conf.config_file_arg);
 215         else
 216                 cf = make_message("%s/.paraslash/server.conf", home);
 217         free(user_list_file);
 218         if (!conf.user_list_given)
 219                 user_list_file = make_message("%s/.paraslash/server.users", home);
 220         else
 221                 user_list_file = para_strdup(conf.user_list_arg);
 222         ret = file_exists(cf);
 223         if (conf.config_file_given && !ret)  {
 224                 ret = -1;
 225                 PARA_EMERG_LOG("can not read config file %s\n", cf);
 226                 goto out;
 227         }
 228         if (ret) {
 229                 int tmp = conf.daemon_given;
 230                 struct server_cmdline_parser_params params = {
 231                         .override = override,
 232                         .initialize = 0,
 233                         .check_required = 1,
 234                         .check_ambiguity = 0,
 235                         .print_errors = !conf.daemon_given
 236                 };
 237                 server_cmdline_parser_config_file(cf, &conf, &params);
 238                 conf.daemon_given = tmp;
 239         }
 240         if (conf.logfile_given) {
 241                 daemon_set_logfile(conf.logfile_arg);
 242                 daemon_open_log_or_die();
 243         }
 244         daemon_set_loglevel(conf.loglevel_arg);
 245         init_colors_or_die();
 246         daemon_set_flag(DF_LOG_PID);
 247         daemon_set_flag(DF_LOG_LL);
 248         daemon_set_flag(DF_LOG_TIME);
 249         if (conf.log_timing_given)
 250                 daemon_set_flag(DF_LOG_TIMING);
 251         ret = 1;
 252 out:
 253         free(cf);
 254         free(home);
 255         if (ret > 0)
 256                 return;
 257         free(user_list_file);
 258         user_list_file = NULL;
 259         exit(EXIT_FAILURE);
 260 }
 261
 262 static void signal_pre_select(struct sched *s, struct task *t)
 263 {
 264         struct signal_task *st = container_of(t, struct signal_task, task);
 265         para_fd_set(st->fd, &s->rfds, &s->max_fileno);
 266 }
 267
 268 /*
 269  * called when server gets SIGHUP or when client invokes hup command.
 270  */
 271 static void handle_sighup(void)
 272 {
 273         PARA_NOTICE_LOG("SIGHUP\n");
 274         parse_config_or_die(1); /* reopens log */
 275         init_user_list(user_list_file); /* reload user list */
 276         if (mmd->afs_pid)
 277                 kill(mmd->afs_pid, SIGHUP);
 278 }
 279
 280 static void signal_post_select(struct sched *s, __a_unused struct task *t)
 281 {
 282         int signum = para_next_signal(&s->rfds);
 283
 284         switch (signum) {
 285         case 0:
 286                 return;
 287         case SIGHUP:
 288                 handle_sighup();
 289                 break;
 290         case SIGCHLD:
 291                 for (;;) {
 292                         pid_t pid;
 293                         int ret = para_reap_child(&pid);
 294                         if (ret <= 0)
 295                                 break;
 296                         if (pid != mmd->afs_pid)
 297                                 continue;
 298                         PARA_EMERG_LOG("fatal: afs died\n");
 299                         kill(0, SIGTERM);
 300                         goto cleanup;
 301                 }
 302                 break;
 303         /* die on sigint/sigterm. Kill all children too. */
 304         case SIGINT:
 305         case SIGTERM:
 306                 PARA_EMERG_LOG("terminating on signal %d\n", signum);
 307                 kill(0, SIGTERM);
 308                 /*
 309                  * We must wait for afs because afs catches SIGINT/SIGTERM.
 310                  * Before reacting to the signal, afs might want to use the
 311                  * shared memory area and the mmd mutex.  If we destroy this
 312                  * mutex too early and afs tries to lock the shared memory
 313                  * area, the call to mutex_lock() will fail and terminate the
 314                  * afs process. This leads to dirty osl tables.
 315                  *
 316                  * There's no such problem with the other children of the
 317                  * server process (the command handlers) as these reset their
 318                  * SIGINT/SIGTERM handlers to the default action, i.e.  these
 319                  * processes get killed immediately by the above kill().
 320                  */
 321                 PARA_INFO_LOG("waiting for afs (pid %d) to die\n",
 322                         (int)mmd->afs_pid);
 323                 waitpid(mmd->afs_pid, NULL, 0);
 324 cleanup:
 325                 free(mmd->afd.afhi.chunk_table);
 326                 close_listed_fds();
 327                 mutex_destroy(mmd_mutex);
 328                 shm_detach(mmd);
 329                 exit(EXIT_FAILURE);
 330         }
 331 }
 332
 333 static void init_signal_task(void)
 334 {
 335         static struct signal_task signal_task_struct,
 336                 *st = &signal_task_struct;
 337
 338         st->task.pre_select = signal_pre_select;
 339         st->task.post_select = signal_post_select;
 340         sprintf(st->task.status, "signal task");
 341
 342         PARA_NOTICE_LOG("setting up signal handling\n");
 343         st->fd = para_signal_init(); /* always successful */
 344         para_install_sighandler(SIGINT);
 345         para_install_sighandler(SIGTERM);
 346         para_install_sighandler(SIGHUP);
 347         para_install_sighandler(SIGCHLD);
 348         para_sigaction(SIGPIPE, SIG_IGN);
 349         add_close_on_fork_list(st->fd);
 350         register_task(&sched, &st->task);
 351 }
 352
 353 static void command_pre_select(struct sched *s, struct task *t)
 354 {
 355         struct server_command_task *sct = container_of(t, struct server_command_task, task);
 356         para_fd_set(sct->listen_fd, &s->rfds, &s->max_fileno);
 357 }
 358
 359 static void command_post_select(struct sched *s, struct task *t)
 360 {
 361         struct server_command_task *sct = container_of(t, struct server_command_task, task);
 362
 363         int new_fd, ret, i;
 364         char *peer_name;
 365         pid_t child_pid;
 366         uint32_t *chunk_table;
 367
 368         ret = para_accept(sct->listen_fd, &s->rfds, NULL, 0, &new_fd);
 369         if (ret <= 0)
 370                 goto out;
 371         peer_name = remote_name(new_fd);
 372         PARA_INFO_LOG("got connection from %s, forking\n", peer_name);
 373         mmd->num_connects++;
 374         mmd->active_connections++;
 375         /*
 376          * The chunk table is a pointer located in the mmd struct that points
 377          * to dynamically allocated memory, i.e. it must be freed by the parent
 378          * and the child. However, as the mmd struct is in a shared memory
 379          * area, there's no guarantee that after the fork this pointer is still
 380          * valid in child context. As it is not used in the child anyway, we
 381          * save it to a local variable before the fork and free the memory via
 382          * that copy in the child directly after the fork.
 383          */
 384         chunk_table = mmd->afd.afhi.chunk_table;
 385         child_pid = fork();
 386         if (child_pid < 0) {
 387                 ret = -ERRNO_TO_PARA_ERROR(errno);
 388                 goto out;
 389         }
 390         if (child_pid) {
 391                 close(new_fd);
 392                 /* parent keeps accepting connections */
 393                 return;
 394         }
 395         /* mmd might already have changed at this point */
 396         free(chunk_table);
 397         alarm(ALARM_TIMEOUT);
 398         close_listed_fds();
 399         para_signal_shutdown();
 400         /*
 401          * put info on who we are serving into argv[0] to make
 402          * client ip visible in top/ps
 403          */
 404         for (i = sct->argc - 1; i >= 0; i--)
 405                 memset(sct->argv[i], 0, strlen(sct->argv[i]));
 406         sprintf(sct->argv[0], "para_server (serving %s)", peer_name);
 407         return handle_connect(new_fd, peer_name);
 408 out:
 409         if (ret < 0)
 410                 PARA_CRIT_LOG("%s\n", para_strerror(-ret));
 411 }
 412
 413 static void init_server_command_task(int argc, char **argv)
 414 {
 415         int ret;
 416         static struct server_command_task server_command_task_struct,
 417                 *sct = &server_command_task_struct;
 418
 419         PARA_NOTICE_LOG("initializing tcp command socket\n");
 420         sct->task.pre_select = command_pre_select;
 421         sct->task.post_select = command_post_select;
 422         sct->argc = argc;
 423         sct->argv = argv;
 424         ret = para_listen_simple(IPPROTO_TCP, conf.port_arg);
 425         if (ret < 0)
 426                 goto err;
 427         sct->listen_fd = ret;
 428         ret = mark_fd_nonblocking(sct->listen_fd);
 429         if (ret < 0)
 430                 goto err;
 431         add_close_on_fork_list(sct->listen_fd); /* child doesn't need the listener */
 432         sprintf(sct->task.status, "server command task");
 433         register_task(&sched, &sct->task);
 434         return;
 435 err:
 436         PARA_EMERG_LOG("%s\n", para_strerror(-ret));
 437         exit(EXIT_FAILURE);
 438 }
 439
 440 static int init_afs(int argc, char **argv)
 441 {
 442         int ret, afs_server_socket[2];
 443         pid_t afs_pid;
 444
 445         ret = socketpair(PF_UNIX, SOCK_DGRAM, 0, afs_server_socket);
 446         if (ret < 0)
 447                 exit(EXIT_FAILURE);
 448         get_random_bytes_or_die((unsigned char *)&afs_socket_cookie,
 449                 sizeof(afs_socket_cookie));
 450         afs_pid = fork();
 451         if (afs_pid < 0)
 452                 exit(EXIT_FAILURE);
 453         if (afs_pid == 0) { /* child (afs) */
 454                 int i;
 455                 for (i = argc - 1; i >= 0; i--)
 456                         memset(argv[i], 0, strlen(argv[i]));
 457                 sprintf(argv[0], "para_server (afs)");
 458                 close(afs_server_socket[0]);
 459                 afs_init(afs_socket_cookie, afs_server_socket[1]);
 460         }
 461         mmd->afs_pid = afs_pid;
 462         close(afs_server_socket[1]);
 463         ret = mark_fd_nonblocking(afs_server_socket[0]);
 464         if (ret < 0)
 465                 exit(EXIT_FAILURE);
 466         add_close_on_fork_list(afs_server_socket[0]);
 467         PARA_INFO_LOG("afs_socket: %d, afs_socket_cookie: %u\n",
 468                 afs_server_socket[0], (unsigned) afs_socket_cookie);
 469         return afs_server_socket[0];
 470 }
 471
 472 static void server_init(int argc, char **argv)
 473 {
 474         struct server_cmdline_parser_params params = {
 475                 .override = 0,
 476                 .initialize = 1,
 477                 .check_required = 0,
 478                 .check_ambiguity = 0,
 479                 .print_errors = 1
 480         };
 481         int afs_socket;
 482
 483         valid_fd_012();
 484         init_random_seed_or_die();
 485         /* parse command line options */
 486         server_cmdline_parser_ext(argc, argv, &conf, &params);
 487         HANDLE_VERSION_FLAG("server", conf);
 488         drop_privileges_or_die(conf.user_arg, conf.group_arg);
 489         /* parse config file, open log and set defaults */
 490         parse_config_or_die(0);
 491         log_welcome("para_server");
 492         init_ipc_or_die(); /* init mmd struct and mmd->lock */
 493         /* make sure, the global now pointer is uptodate */
 494         gettimeofday(now, NULL);
 495         set_server_start_time(now);
 496         init_user_list(user_list_file);
 497         /* become daemon */
 498         if (conf.daemon_given)
 499                 daemonize(true /* parent waits for SIGTERM */);
 500         PARA_NOTICE_LOG("initializing audio format handlers\n");
 501         afh_init();
 502
 503         /*
 504          * Although afs uses its own signal handling we must ignore SIGUSR1
 505          * _before_ the afs child process gets born by init_afs() below.  It's
 506          * racy to do this in the child because the parent might send SIGUSR1
 507          * before the child gets a chance to ignore this signal -- only the
 508          * good die young.
 509          */
 510         para_sigaction(SIGUSR1, SIG_IGN);
 511         /*
 512          * We have to block SIGCHLD before the afs process is being forked off.
 513          * Otherwise, para_server does not notice if afs dies before the
 514          * SIGCHLD handler has been installed for the parent process by
 515          * init_signal_task() below.
 516          */
 517         para_block_signal(SIGCHLD);
 518         PARA_NOTICE_LOG("initializing the audio file selector\n");
 519         afs_socket = init_afs(argc, argv);
 520         init_signal_task();
 521         para_unblock_signal(SIGCHLD);
 522         PARA_NOTICE_LOG("initializing virtual streaming system\n");
 523         init_vss_task(afs_socket, &sched);
 524         init_server_command_task(argc, argv);
 525         if (conf.daemon_given)
 526                 kill(getppid(), SIGTERM);
 527         PARA_NOTICE_LOG("server init complete\n");
 528 }
 529
 530 static void status_refresh(void)
 531 {
 532         static int prev_uptime = -1, prev_events = -1;
 533         int uptime = get_server_uptime(now);
 534
 535         if (prev_events != mmd->events)
 536                 goto out;
 537         if (mmd->new_vss_status_flags != mmd->vss_status_flags)
 538                 goto out_inc_events;
 539         if (uptime / 60 != prev_uptime / 60)
 540                 goto out_inc_events;
 541         return;
 542 out_inc_events:
 543         mmd->events++;
 544 out:
 545         prev_uptime = uptime;
 546         prev_events = mmd->events;
 547         mmd->vss_status_flags = mmd->new_vss_status_flags;
 548         PARA_DEBUG_LOG("%d events, forcing status update\n", mmd->events);
 549         killpg(0, SIGUSR1);
 550 }
 551
 552 static int server_select(int max_fileno, fd_set *readfds, fd_set *writefds,
 553                 struct timeval *timeout_tv)
 554 {
 555         int ret;
 556
 557         status_refresh();
 558         mutex_unlock(mmd_mutex);
 559         ret = para_select(max_fileno + 1, readfds, writefds, timeout_tv);
 560         mutex_lock(mmd_mutex);
 561         return ret;
 562 }
 563
 564 /**
 565  * The main function of para_server.
 566  *
 567  * \param argc Usual argument count.
 568  * \param argv Usual argument vector.
 569  *
 570  * \return EXIT_SUCCESS or EXIT_FAILURE.
 571  */
 572 int main(int argc, char *argv[])
 573 {
 574         int ret;
 575
 576         sched.default_timeout.tv_sec = 1;
 577         sched.select_function = server_select;
 578
 579         server_init(argc, argv);
 580         mutex_lock(mmd_mutex);
 581         ret = schedule(&sched);
 582         if (ret < 0) {
 583                 PARA_EMERG_LOG("%s\n", para_strerror(-ret));
 584                 exit(EXIT_FAILURE);
 585         }
 586         exit(EXIT_SUCCESS);
 587 }