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 <regex.h>
  68 #include <osl.h>
  69
  70 #include "para.h"
  71 #include "error.h"
  72 #include "crypt.h"
  73 #include "server.cmdline.h"
  74 #include "afh.h"
  75 #include "string.h"
  76 #include "afs.h"
  77 #include "server.h"
  78 #include "vss.h"
  79 #include "config.h"
  80 #include "close_on_fork.h"
  81 #include "list.h"
  82 #include "send.h"
  83 #include "net.h"
  84 #include "daemon.h"
  85 #include "ipc.h"
  86 #include "fd.h"
  87 #include "sched.h"
  88 #include "signal.h"
  89 #include "user_list.h"
  90 #include "color.h"
  91
  92 /** Define the array of error lists needed by para_server. */
  93 INIT_SERVER_ERRLISTS;
  94
  95 /** Shut down non-authorized connections after that many seconds. */
  96 #define ALARM_TIMEOUT 10
  97
  98 /**
  99  * Pointer to shared memory area for communication between para_server
 100  * and its children. Exported to vss.c. command.c and to afs.
 101  */
 102 struct misc_meta_data *mmd;
 103
 104 /**
 105  * The configuration of para_server
 106  *
 107  * It also contains the options for the audio file selector, audio format
 108  * handler and all supported senders.
 109  */
 110 struct server_args_info conf;
 111
 112 /** A random value used in child context for authentication. */
 113 uint32_t afs_socket_cookie;
 114
 115 /** The mutex protecting the shared memory area containing the mmd struct. */
 116 int mmd_mutex;
 117
 118 /** The file containing user information (public key, permissions). */
 119 static char *user_list_file = NULL;
 120
 121
 122 /** The task responsible for server command handling. */
 123 struct server_command_task {
 124         /** TCP port on which para_server listens for connections. */
 125         int listen_fd;
 126         /** Copied from para_server's main function. */
 127         int argc;
 128         /** Argument vector passed to para_server's main function. */
 129         char **argv;
 130         /** The command task structure for scheduling. */
 131         struct task task;
 132 };
 133
 134 static int want_colors(void)
 135 {
 136         if (conf.color_arg == color_arg_no)
 137                 return 0;
 138         if (conf.color_arg == color_arg_yes)
 139                 return 1;
 140         if (conf.logfile_given)
 141                 return 0;
 142         return isatty(STDERR_FILENO);
 143 }
 144
 145 static void init_colors_or_die(void)
 146 {
 147         int ret, i;
 148
 149         if (!want_colors())
 150                 return;
 151         daemon_set_flag(DF_COLOR_LOG);
 152         daemon_set_default_log_colors();
 153         for (i = 0; i < conf.log_color_given; i++) {
 154                 ret = daemon_set_log_color(conf.log_color_arg[i]);
 155                 if (ret < 0)
 156                         exit(EXIT_FAILURE);
 157         }
 158 }
 159
 160 /*
 161  * setup shared memory area and get mutex for locking
 162  */
 163 static void init_ipc_or_die(void)
 164 {
 165         void *shm;
 166         int shmid, ret = shm_new(sizeof(struct misc_meta_data));
 167
 168         if (ret < 0)
 169                 goto err_out;
 170         shmid = ret;
 171         ret = shm_attach(shmid, ATTACH_RW, &shm);
 172         shm_destroy(shmid);
 173         if (ret < 0)
 174                 goto err_out;
 175         mmd = shm;
 176
 177         ret = mutex_new();
 178         if (ret < 0)
 179                 goto err_out;
 180         mmd_mutex = ret;
 181
 182         mmd->num_played = 0;
 183         mmd->num_commands = 0;
 184         mmd->events = 0;
 185         mmd->num_connects = 0;
 186         mmd->active_connections = 0;
 187         mmd->vss_status_flags = VSS_NEXT;
 188         mmd->new_vss_status_flags = VSS_NEXT;
 189         return;
 190 err_out:
 191         PARA_EMERG_LOG("%s\n", para_strerror(-ret));
 192         exit(EXIT_FAILURE);
 193 }
 194
 195 /**
 196  * (Re-)read the server configuration files.
 197  *
 198  * \param override Passed to gengetopt to activate the override feature.
 199  *
 200  * This function also re-opens the logfile and sets the global \a
 201  * user_list_file variable.
 202  */
 203 void parse_config_or_die(int override)
 204 {
 205         char *home = para_homedir();
 206         int ret;
 207         char *cf;
 208
 209         daemon_close_log();
 210         if (conf.config_file_given)
 211                 cf = para_strdup(conf.config_file_arg);
 212         else
 213                 cf = make_message("%s/.paraslash/server.conf", home);
 214         free(user_list_file);
 215         if (!conf.user_list_given)
 216                 user_list_file = make_message("%s/.paraslash/server.users", home);
 217         else
 218                 user_list_file = para_strdup(conf.user_list_arg);
 219         ret = file_exists(cf);
 220         if (conf.config_file_given && !ret)  {
 221                 ret = -1;
 222                 PARA_EMERG_LOG("can not read config file %s\n", cf);
 223                 goto out;
 224         }
 225         if (ret) {
 226                 int tmp = conf.daemon_given;
 227                 struct server_cmdline_parser_params params = {
 228                         .override = override,
 229                         .initialize = 0,
 230                         .check_required = 1,
 231                         .check_ambiguity = 0,
 232                         .print_errors = !conf.daemon_given
 233                 };
 234                 server_cmdline_parser_config_file(cf, &conf, &params);
 235                 conf.daemon_given = tmp;
 236         }
 237         if (conf.logfile_given) {
 238                 daemon_set_logfile(conf.logfile_arg);
 239                 daemon_open_log_or_die();
 240         }
 241         daemon_set_loglevel(conf.loglevel_arg);
 242         init_colors_or_die();
 243         daemon_set_flag(DF_LOG_PID);
 244         daemon_set_flag(DF_LOG_LL);
 245         daemon_set_flag(DF_LOG_TIME);
 246         ret = 1;
 247 out:
 248         free(cf);
 249         free(home);
 250         if (ret > 0)
 251                 return;
 252         free(user_list_file);
 253         user_list_file = NULL;
 254         exit(EXIT_FAILURE);
 255 }
 256
 257 static void signal_pre_select(struct sched *s, struct task *t)
 258 {
 259         struct signal_task *st = container_of(t, struct signal_task, task);
 260         para_fd_set(st->fd, &s->rfds, &s->max_fileno);
 261 }
 262
 263 /*
 264  * called when server gets SIGHUP or when client invokes hup command.
 265  */
 266 static void handle_sighup(void)
 267 {
 268         PARA_NOTICE_LOG("SIGHUP\n");
 269         parse_config_or_die(1); /* reopens log */
 270         init_user_list(user_list_file); /* reload user list */
 271         if (mmd->afs_pid)
 272                 kill(mmd->afs_pid, SIGHUP);
 273 }
 274
 275 static void signal_post_select(struct sched *s, struct task *t)
 276 {
 277         struct signal_task *st = container_of(t, struct signal_task, task);
 278
 279         if (!FD_ISSET(st->fd, &s->rfds))
 280                 return;
 281
 282         st->signum = para_next_signal();
 283         switch (st->signum) {
 284         case SIGHUP:
 285                 handle_sighup();
 286                 break;
 287         case SIGCHLD:
 288                 for (;;) {
 289                         pid_t pid;
 290                         int ret = para_reap_child(&pid);
 291                         if (ret <= 0)
 292                                 break;
 293                         if (pid != mmd->afs_pid)
 294                                 continue;
 295                         PARA_EMERG_LOG("fatal: afs died\n");
 296                         kill(0, SIGTERM);
 297                         goto cleanup;
 298                 }
 299                 break;
 300         /* die on sigint/sigterm. Kill all children too. */
 301         case SIGINT:
 302         case SIGTERM:
 303                 PARA_EMERG_LOG("terminating on signal %d\n", st->signum);
 304                 kill(0, SIGTERM);
 305                 /*
 306                  * We must wait for afs because afs catches SIGINT/SIGTERM.
 307                  * Before reacting to the signal, afs might want to use the
 308                  * shared memory area and the mmd mutex.  If we destroy this
 309                  * mutex too early and afs tries to lock the shared memory
 310                  * area, the call to mutex_lock() will fail and terminate the
 311                  * afs process. This leads to dirty osl tables.
 312                  *
 313                  * There's no such problem with the other children of the
 314                  * server process (the command handlers) as these reset their
 315                  * SIGINT/SIGTERM handlers to the default action, i.e.  these
 316                  * processes get killed immediately by the above kill().
 317                  */
 318                 PARA_INFO_LOG("waiting for afs (pid %d) to die\n",
 319                         (int)mmd->afs_pid);
 320                 waitpid(mmd->afs_pid, NULL, 0);
 321 cleanup:
 322                 free(mmd->afd.afhi.chunk_table);
 323                 close_listed_fds();
 324                 mutex_destroy(mmd_mutex);
 325                 shm_detach(mmd);
 326                 exit(EXIT_FAILURE);
 327         }
 328 }
 329
 330 static void init_signal_task(void)
 331 {
 332         static struct signal_task signal_task_struct,
 333                 *st = &signal_task_struct;
 334
 335         st->task.pre_select = signal_pre_select;
 336         st->task.post_select = signal_post_select;
 337         sprintf(st->task.status, "signal task");
 338
 339         PARA_NOTICE_LOG("setting up signal handling\n");
 340         st->fd = para_signal_init(); /* always successful */
 341         para_install_sighandler(SIGINT);
 342         para_install_sighandler(SIGTERM);
 343         para_install_sighandler(SIGHUP);
 344         para_install_sighandler(SIGCHLD);
 345         para_sigaction(SIGPIPE, SIG_IGN);
 346         add_close_on_fork_list(st->fd);
 347         register_task(&st->task);
 348 }
 349
 350 static void command_pre_select(struct sched *s, struct task *t)
 351 {
 352         struct server_command_task *sct = container_of(t, struct server_command_task, task);
 353         para_fd_set(sct->listen_fd, &s->rfds, &s->max_fileno);
 354 }
 355
 356 static void command_post_select(struct sched *s, struct task *t)
 357 {
 358         struct server_command_task *sct = container_of(t, struct server_command_task, task);
 359
 360         int new_fd, ret, i;
 361         char *peer_name;
 362         pid_t child_pid;
 363         uint32_t *chunk_table;
 364
 365         if (!FD_ISSET(sct->listen_fd, &s->rfds))
 366                 return;
 367         ret = para_accept(sct->listen_fd, NULL, 0);
 368         if (ret < 0)
 369                 goto out;
 370         new_fd = ret;
 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(AF_UNSPEC, 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         register_task(&sct->task);
 433         return;
 434 err:
 435         PARA_EMERG_LOG("%s\n", para_strerror(-ret));
 436         exit(EXIT_FAILURE);
 437 }
 438
 439 static int init_afs(void)
 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                 close(afs_server_socket[0]);
 454                 afs_init(afs_socket_cookie, afs_server_socket[1]);
 455         }
 456         mmd->afs_pid = afs_pid;
 457         close(afs_server_socket[1]);
 458         ret = mark_fd_nonblocking(afs_server_socket[0]);
 459         if (ret < 0)
 460                 exit(EXIT_FAILURE);
 461         add_close_on_fork_list(afs_server_socket[0]);
 462         PARA_INFO_LOG("afs_socket: %d, afs_socket_cookie: %u\n",
 463                 afs_server_socket[0], (unsigned) afs_socket_cookie);
 464         return afs_server_socket[0];
 465 }
 466
 467 __noreturn static void tmp_sigchld_handler(__a_unused int s)
 468 {
 469         PARA_EMERG_LOG("caught early SIGCHLD\n");
 470         exit(EXIT_FAILURE);
 471 }
 472
 473 static void server_init(int argc, char **argv)
 474 {
 475         struct server_cmdline_parser_params params = {
 476                 .override = 0,
 477                 .initialize = 1,
 478                 .check_required = 0,
 479                 .check_ambiguity = 0,
 480                 .print_errors = 1
 481         };
 482         int afs_socket;
 483
 484         valid_fd_012();
 485         init_random_seed_or_die();
 486         /* parse command line options */
 487         server_cmdline_parser_ext(argc, argv, &conf, &params);
 488         HANDLE_VERSION_FLAG("server", conf);
 489         drop_privileges_or_die(conf.user_arg, conf.group_arg);
 490         /* parse config file, open log and set defaults */
 491         parse_config_or_die(0);
 492         log_welcome("para_server");
 493         init_ipc_or_die(); /* init mmd struct and mmd->lock */
 494         /* make sure, the global now pointer is uptodate */
 495         gettimeofday(now, NULL);
 496         server_uptime(UPTIME_SET); /* reset server uptime */
 497         init_user_list(user_list_file);
 498         /* become daemon */
 499         if (conf.daemon_given)
 500                 daemonize();
 501         PARA_NOTICE_LOG("initializing audio format handlers\n");
 502         afh_init();
 503
 504         /*
 505          * Although afs uses its own signal handling we must ignore SIGUSR1
 506          * _before_ the afs child process gets born by init_afs() below.  It's
 507          * racy to do this in the child because the parent might send SIGUSR1
 508          * before the child gets a chance to ignore this signal -- only the
 509          * good die young.
 510          */
 511         para_sigaction(SIGUSR1, SIG_IGN);
 512         /*
 513          * We have to install a SIGCHLD handler before the afs process is being
 514          * forked off. Otherwise, para_server does not notice if afs dies before
 515          * the SIGCHLD handler has been installed by init_signal_task() below.
 516          */
 517         para_sigaction(SIGCHLD, tmp_sigchld_handler);
 518         PARA_NOTICE_LOG("initializing the audio file selector\n");
 519         afs_socket = init_afs();
 520         init_signal_task();
 521         PARA_NOTICE_LOG("initializing virtual streaming system\n");
 522         init_vss_task(afs_socket);
 523         init_server_command_task(argc, argv);
 524         PARA_NOTICE_LOG("server init complete\n");
 525 }
 526
 527 static void status_refresh(void)
 528 {
 529         static int prev_uptime = -1, prev_events = -1;
 530         int uptime = server_uptime(UPTIME_GET), ret = 1;
 531
 532         if (prev_events != mmd->events)
 533                 goto out;
 534         if (mmd->new_vss_status_flags != mmd->vss_status_flags)
 535                 goto out_inc_events;
 536         if (uptime / 60 != prev_uptime / 60)
 537                 goto out_inc_events;
 538         return;
 539 out_inc_events:
 540         mmd->events++;
 541 out:
 542         prev_uptime = uptime;
 543         prev_events = mmd->events;
 544         mmd->vss_status_flags = mmd->new_vss_status_flags;
 545         if (ret) {
 546                 PARA_DEBUG_LOG("%d events, forcing status update\n",
 547                         mmd->events);
 548                 killpg(0, SIGUSR1);
 549         }
 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         static struct sched s = {
 576                 .default_timeout = {
 577                         .tv_sec = 1,
 578                         .tv_usec = 0
 579                 },
 580                 .select_function = server_select
 581         };
 582         server_init(argc, argv);
 583         mutex_lock(mmd_mutex);
 584         ret = schedule(&s);
 585         if (ret < 0) {
 586                 PARA_EMERG_LOG("%s\n", para_strerror(-ret));
 587                 exit(EXIT_FAILURE);
 588         }
 589         exit(EXIT_SUCCESS);
 590 }