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  *
  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 #include <stdbool.h>
  72
  73 #include "para.h"
  74 #include "error.h"
  75 #include "crypt.h"
  76 #include "server.cmdline.h"
  77 #include "afh.h"
  78 #include "string.h"
  79 #include "afs.h"
  80 #include "server.h"
  81 #include "list.h"
  82 #include "send.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 "sched.h"
  91 #include "signal.h"
  92 #include "user_list.h"
  93 #include "color.h"
  94 #include "version.h"
  95
  96 /** Define the array of error lists needed by para_server. */
  97 INIT_SERVER_ERRLISTS;
  98
  99 /** Shut down non-authorized connections after that many seconds. */
 100 #define ALARM_TIMEOUT 10
 101
 102 /**
 103  * Pointer to shared memory area for communication between para_server
 104  * and its children. Exported to vss.c. command.c and to afs.
 105  */
 106 struct misc_meta_data *mmd;
 107
 108 /**
 109  * The configuration of para_server
 110  *
 111  * It also contains the options for the audio file selector, audio format
 112  * handler and all supported senders.
 113  */
 114 struct server_args_info conf;
 115
 116 /** A random value used in child context for authentication. */
 117 uint32_t afs_socket_cookie;
 118
 119 /** The mutex protecting the shared memory area containing the mmd struct. */
 120 int mmd_mutex;
 121
 122 /** The file containing user information (public key, permissions). */
 123 static char *user_list_file = NULL;
 124
 125
 126 /** The task responsible for server command handling. */
 127 struct server_command_task {
 128         /** TCP port on which para_server listens for connections. */
 129         int listen_fd;
 130         /** Copied from para_server's main function. */
 131         int argc;
 132         /** Argument vector passed to para_server's main function. */
 133         char **argv;
 134         /** The command task structure for scheduling. */
 135         struct task task;
 136 };
 137
 138 static int want_colors(void)
 139 {
 140         if (conf.color_arg == color_arg_no)
 141                 return 0;
 142         if (conf.color_arg == color_arg_yes)
 143                 return 1;
 144         if (conf.logfile_given)
 145                 return 0;
 146         return isatty(STDERR_FILENO);
 147 }
 148
 149 static void init_colors_or_die(void)
 150 {
 151         int i;
 152
 153         if (!want_colors())
 154                 return;
 155         daemon_set_flag(DF_COLOR_LOG);
 156         daemon_set_default_log_colors();
 157         for (i = 0; i < conf.log_color_given; i++)
 158                 daemon_set_log_color_or_die(conf.log_color_arg[i]);
 159 }
 160
 161 /*
 162  * setup shared memory area and get mutex for locking
 163  */
 164 static void init_ipc_or_die(void)
 165 {
 166         void *shm;
 167         int shmid, ret = shm_new(sizeof(struct misc_meta_data));
 168
 169         if (ret < 0)
 170                 goto err_out;
 171         shmid = ret;
 172         ret = shm_attach(shmid, ATTACH_RW, &shm);
 173         shm_destroy(shmid);
 174         if (ret < 0)
 175                 goto err_out;
 176         mmd = shm;
 177
 178         ret = mutex_new();
 179         if (ret < 0)
 180                 goto err_out;
 181         mmd_mutex = ret;
 182
 183         mmd->num_played = 0;
 184         mmd->num_commands = 0;
 185         mmd->events = 0;
 186         mmd->num_connects = 0;
 187         mmd->active_connections = 0;
 188         mmd->vss_status_flags = VSS_NEXT;
 189         mmd->new_vss_status_flags = VSS_NEXT;
 190         return;
 191 err_out:
 192         PARA_EMERG_LOG("%s\n", para_strerror(-ret));
 193         exit(EXIT_FAILURE);
 194 }
 195
 196 /**
 197  * (Re-)read the server configuration files.
 198  *
 199  * \param override Passed to gengetopt to activate the override feature.
 200  *
 201  * This function also re-opens the logfile and sets the global \a
 202  * user_list_file variable.
 203  */
 204 void parse_config_or_die(int override)
 205 {
 206         char *home = para_homedir();
 207         int ret;
 208         char *cf;
 209
 210         daemon_close_log();
 211         if (conf.config_file_given)
 212                 cf = para_strdup(conf.config_file_arg);
 213         else
 214                 cf = make_message("%s/.paraslash/server.conf", home);
 215         free(user_list_file);
 216         if (!conf.user_list_given)
 217                 user_list_file = make_message("%s/.paraslash/server.users", home);
 218         else
 219                 user_list_file = para_strdup(conf.user_list_arg);
 220         ret = file_exists(cf);
 221         if (conf.config_file_given && !ret)  {
 222                 ret = -1;
 223                 PARA_EMERG_LOG("can not read config file %s\n", cf);
 224                 goto out;
 225         }
 226         if (ret) {
 227                 int tmp = conf.daemon_given;
 228                 struct server_cmdline_parser_params params = {
 229                         .override = override,
 230                         .initialize = 0,
 231                         .check_required = 1,
 232                         .check_ambiguity = 0,
 233                         .print_errors = !conf.daemon_given
 234                 };
 235                 server_cmdline_parser_config_file(cf, &conf, &params);
 236                 conf.daemon_given = tmp;
 237         }
 238         if (conf.logfile_given) {
 239                 daemon_set_logfile(conf.logfile_arg);
 240                 daemon_open_log_or_die();
 241         }
 242         daemon_set_loglevel(conf.loglevel_arg);
 243         init_colors_or_die();
 244         daemon_set_flag(DF_LOG_PID);
 245         daemon_set_flag(DF_LOG_LL);
 246         daemon_set_flag(DF_LOG_TIME);
 247         if (conf.log_timing_given)
 248                 daemon_set_flag(DF_LOG_TIMING);
 249         ret = 1;
 250 out:
 251         free(cf);
 252         free(home);
 253         if (ret > 0)
 254                 return;
 255         free(user_list_file);
 256         user_list_file = NULL;
 257         exit(EXIT_FAILURE);
 258 }
 259
 260 static void signal_pre_select(struct sched *s, struct task *t)
 261 {
 262         struct signal_task *st = container_of(t, struct signal_task, task);
 263         para_fd_set(st->fd, &s->rfds, &s->max_fileno);
 264 }
 265
 266 /*
 267  * called when server gets SIGHUP or when client invokes hup command.
 268  */
 269 static void handle_sighup(void)
 270 {
 271         PARA_NOTICE_LOG("SIGHUP\n");
 272         parse_config_or_die(1); /* reopens log */
 273         init_user_list(user_list_file); /* reload user list */
 274         if (mmd->afs_pid)
 275                 kill(mmd->afs_pid, SIGHUP);
 276 }
 277
 278 static void signal_post_select(struct sched *s, __a_unused struct task *t)
 279 {
 280         int signum = para_next_signal(&s->rfds);
 281
 282         switch (signum) {
 283         case 0:
 284                 return;
 285         case SIGHUP:
 286                 handle_sighup();
 287                 break;
 288         case SIGCHLD:
 289                 for (;;) {
 290                         pid_t pid;
 291                         int ret = para_reap_child(&pid);
 292                         if (ret <= 0)
 293                                 break;
 294                         if (pid != mmd->afs_pid)
 295                                 continue;
 296                         PARA_EMERG_LOG("fatal: afs died\n");
 297                         kill(0, SIGTERM);
 298                         goto cleanup;
 299                 }
 300                 break;
 301         /* die on sigint/sigterm. Kill all children too. */
 302         case SIGINT:
 303         case SIGTERM:
 304                 PARA_EMERG_LOG("terminating on signal %d\n", signum);
 305                 kill(0, SIGTERM);
 306                 /*
 307                  * We must wait for afs because afs catches SIGINT/SIGTERM.
 308                  * Before reacting to the signal, afs might want to use the
 309                  * shared memory area and the mmd mutex.  If we destroy this
 310                  * mutex too early and afs tries to lock the shared memory
 311                  * area, the call to mutex_lock() will fail and terminate the
 312                  * afs process. This leads to dirty osl tables.
 313                  *
 314                  * There's no such problem with the other children of the
 315                  * server process (the command handlers) as these reset their
 316                  * SIGINT/SIGTERM handlers to the default action, i.e.  these
 317                  * processes get killed immediately by the above kill().
 318                  */
 319                 PARA_INFO_LOG("waiting for afs (pid %d) to die\n",
 320                         (int)mmd->afs_pid);
 321                 waitpid(mmd->afs_pid, NULL, 0);
 322 cleanup:
 323                 free(mmd->afd.afhi.chunk_table);
 324                 close_listed_fds();
 325                 mutex_destroy(mmd_mutex);
 326                 shm_detach(mmd);
 327                 exit(EXIT_FAILURE);
 328         }
 329 }
 330
 331 static void init_signal_task(void)
 332 {
 333         static struct signal_task signal_task_struct,
 334                 *st = &signal_task_struct;
 335
 336         st->task.pre_select = signal_pre_select;
 337         st->task.post_select = signal_post_select;
 338         sprintf(st->task.status, "signal task");
 339
 340         PARA_NOTICE_LOG("setting up signal handling\n");
 341         st->fd = para_signal_init(); /* always successful */
 342         para_install_sighandler(SIGINT);
 343         para_install_sighandler(SIGTERM);
 344         para_install_sighandler(SIGHUP);
 345         para_install_sighandler(SIGCHLD);
 346         para_sigaction(SIGPIPE, SIG_IGN);
 347         add_close_on_fork_list(st->fd);
 348         register_task(&st->task);
 349 }
 350
 351 static void command_pre_select(struct sched *s, struct task *t)
 352 {
 353         struct server_command_task *sct = container_of(t, struct server_command_task, task);
 354         para_fd_set(sct->listen_fd, &s->rfds, &s->max_fileno);
 355 }
 356
 357 static void command_post_select(struct sched *s, struct task *t)
 358 {
 359         struct server_command_task *sct = container_of(t, struct server_command_task, task);
 360
 361         int new_fd, ret, i;
 362         char *peer_name;
 363         pid_t child_pid;
 364         uint32_t *chunk_table;
 365
 366         ret = para_accept(sct->listen_fd, &s->rfds, NULL, 0, &new_fd);
 367         if (ret <= 0)
 368                 goto out;
 369         peer_name = remote_name(new_fd);
 370         PARA_INFO_LOG("got connection from %s, forking\n", peer_name);
 371         mmd->num_connects++;
 372         mmd->active_connections++;
 373         /*
 374          * The chunk table is a pointer located in the mmd struct that points
 375          * to dynamically allocated memory, i.e. it must be freed by the parent
 376          * and the child. However, as the mmd struct is in a shared memory
 377          * area, there's no guarantee that after the fork this pointer is still
 378          * valid in child context. As it is not used in the child anyway, we
 379          * save it to a local variable before the fork and free the memory via
 380          * that copy in the child directly after the fork.
 381          */
 382         chunk_table = mmd->afd.afhi.chunk_table;
 383         child_pid = fork();
 384         if (child_pid < 0) {
 385                 ret = -ERRNO_TO_PARA_ERROR(errno);
 386                 goto out;
 387         }
 388         if (child_pid) {
 389                 close(new_fd);
 390                 /* parent keeps accepting connections */
 391                 return;
 392         }
 393         /* mmd might already have changed at this point */
 394         free(chunk_table);
 395         alarm(ALARM_TIMEOUT);
 396         close_listed_fds();
 397         para_signal_shutdown();
 398         /*
 399          * put info on who we are serving into argv[0] to make
 400          * client ip visible in top/ps
 401          */
 402         for (i = sct->argc - 1; i >= 0; i--)
 403                 memset(sct->argv[i], 0, strlen(sct->argv[i]));
 404         sprintf(sct->argv[0], "para_server (serving %s)", peer_name);
 405         return handle_connect(new_fd, peer_name);
 406 out:
 407         if (ret < 0)
 408                 PARA_CRIT_LOG("%s\n", para_strerror(-ret));
 409 }
 410
 411 static void init_server_command_task(int argc, char **argv)
 412 {
 413         int ret;
 414         static struct server_command_task server_command_task_struct,
 415                 *sct = &server_command_task_struct;
 416
 417         PARA_NOTICE_LOG("initializing tcp command socket\n");
 418         sct->task.pre_select = command_pre_select;
 419         sct->task.post_select = command_post_select;
 420         sct->argc = argc;
 421         sct->argv = argv;
 422         ret = para_listen_simple(IPPROTO_TCP, conf.port_arg);
 423         if (ret < 0)
 424                 goto err;
 425         sct->listen_fd = ret;
 426         ret = mark_fd_nonblocking(sct->listen_fd);
 427         if (ret < 0)
 428                 goto err;
 429         add_close_on_fork_list(sct->listen_fd); /* child doesn't need the listener */
 430         sprintf(sct->task.status, "server command task");
 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         pid_t afs_pid;
 442
 443         ret = socketpair(PF_UNIX, SOCK_DGRAM, 0, afs_server_socket);
 444         if (ret < 0)
 445                 exit(EXIT_FAILURE);
 446         get_random_bytes_or_die((unsigned char *)&afs_socket_cookie,
 447                 sizeof(afs_socket_cookie));
 448         afs_pid = fork();
 449         if (afs_pid < 0)
 450                 exit(EXIT_FAILURE);
 451         if (afs_pid == 0) { /* child (afs) */
 452                 close(afs_server_socket[0]);
 453                 afs_init(afs_socket_cookie, afs_server_socket[1]);
 454         }
 455         mmd->afs_pid = afs_pid;
 456         close(afs_server_socket[1]);
 457         ret = mark_fd_nonblocking(afs_server_socket[0]);
 458         if (ret < 0)
 459                 exit(EXIT_FAILURE);
 460         add_close_on_fork_list(afs_server_socket[0]);
 461         PARA_INFO_LOG("afs_socket: %d, afs_socket_cookie: %u\n",
 462                 afs_server_socket[0], (unsigned) afs_socket_cookie);
 463         return afs_server_socket[0];
 464 }
 465
 466 __noreturn static void tmp_sigchld_handler(__a_unused int s)
 467 {
 468         PARA_EMERG_LOG("caught early SIGCHLD\n");
 469         exit(EXIT_FAILURE);
 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         server_uptime(UPTIME_SET); /* reset server uptime */
 496         init_user_list(user_list_file);
 497         /* become daemon */
 498         if (conf.daemon_given)
 499                 daemonize();
 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 install a SIGCHLD handler before the afs process is being
 513          * forked off. Otherwise, para_server does not notice if afs dies before
 514          * the SIGCHLD handler has been installed by init_signal_task() below.
 515          */
 516         para_sigaction(SIGCHLD, tmp_sigchld_handler);
 517         PARA_NOTICE_LOG("initializing the audio file selector\n");
 518         afs_socket = init_afs();
 519         init_signal_task();
 520         PARA_NOTICE_LOG("initializing virtual streaming system\n");
 521         init_vss_task(afs_socket);
 522         init_server_command_task(argc, argv);
 523         PARA_NOTICE_LOG("server init complete\n");
 524 }
 525
 526 static void status_refresh(void)
 527 {
 528         static int prev_uptime = -1, prev_events = -1;
 529         int uptime = server_uptime(UPTIME_GET), ret = 1;
 530
 531         if (prev_events != mmd->events)
 532                 goto out;
 533         if (mmd->new_vss_status_flags != mmd->vss_status_flags)
 534                 goto out_inc_events;
 535         if (uptime / 60 != prev_uptime / 60)
 536                 goto out_inc_events;
 537         return;
 538 out_inc_events:
 539         mmd->events++;
 540 out:
 541         prev_uptime = uptime;
 542         prev_events = mmd->events;
 543         mmd->vss_status_flags = mmd->new_vss_status_flags;
 544         if (ret) {
 545                 PARA_DEBUG_LOG("%d events, forcing status update\n",
 546                         mmd->events);
 547                 killpg(0, SIGUSR1);
 548         }
 549 }
 550
 551 static int server_select(int max_fileno, fd_set *readfds, fd_set *writefds,
 552                 struct timeval *timeout_tv)
 553 {
 554         int ret;
 555
 556         status_refresh();
 557         mutex_unlock(mmd_mutex);
 558         ret = para_select(max_fileno + 1, readfds, writefds, timeout_tv);
 559         mutex_lock(mmd_mutex);
 560         return ret;
 561 }
 562
 563 /**
 564  * The main function of para_server.
 565  *
 566  * \param argc Usual argument count.
 567  * \param argv Usual argument vector.
 568  *
 569  * \return EXIT_SUCCESS or EXIT_FAILURE.
 570  */
 571 int main(int argc, char *argv[])
 572 {
 573         int ret;
 574         static struct sched s = {
 575                 .default_timeout = {
 576                         .tv_sec = 1,
 577                         .tv_usec = 0
 578                 },
 579                 .select_function = server_select
 580         };
 581         server_init(argc, argv);
 582         mutex_lock(mmd_mutex);
 583         ret = schedule(&s);
 584         if (ret < 0) {
 585                 PARA_EMERG_LOG("%s\n", para_strerror(-ret));
 586                 exit(EXIT_FAILURE);
 587         }
 588         exit(EXIT_SUCCESS);
 589 }