server.c

   1 /*
   2  * Copyright (C) 1997 Andre Noll <maan@tuebingen.mpg.de>
   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  * \mainpage Main data structures:
  11  *
  12  *      - Server: \ref server_command, \ref sender,
  13  *      - Audio file selector: \ref afs_info, \ref afs_table,
  14  *      - Audio format handler: \ref audio_format_handler, \ref afh_info
  15  *      - Receivers/filters/writers: \ref receiver, \ref receiver_node,
  16  *        \ref filter, \ref filter_node, \ref writer_node, \ref writer.
  17  *
  18  * Selected APIs:
  19  *
  20  *      - Scheduling: \ref sched.h,
  21  *      - Buffer trees: \ref buffer_tree.h,
  22  *      - Sideband API: \ref sideband.h,
  23  *      - Crypto: \ref crypt.h, \ref crypt_backend.h,
  24  *      - Error subsystem: \ref error.h, \ref error2.c,
  25  *      - Inter process communication: \ref ipc.h,
  26  *      - Forward error correction: \ref fec.h,
  27  *      - Daemons: \ref daemon.h,
  28  *      - Mixer API: \ref mix.h,
  29  *      - Interactive sessions: \ref interactive.h,
  30  *      - File descriptors: \ref fd.h,
  31  *      - Signals: \ref signal.h,
  32  *      - Networking: \ref net.h,
  33  *      - Time: \ref time.c,
  34  *      - Doubly linked lists: \ref list.h.
  35  */
  36
  37 #include <netinet/in.h>
  38 #include <sys/socket.h>
  39 #include <signal.h>
  40 #include <regex.h>
  41 #include <osl.h>
  42 #include <sys/types.h>
  43 #include <arpa/inet.h>
  44 #include <sys/un.h>
  45 #include <netdb.h>
  46
  47 #include "para.h"
  48 #include "error.h"
  49 #include "crypt.h"
  50 #include "server.cmdline.h"
  51 #include "afh.h"
  52 #include "string.h"
  53 #include "afs.h"
  54 #include "server.h"
  55 #include "list.h"
  56 #include "send.h"
  57 #include "sched.h"
  58 #include "vss.h"
  59 #include "config.h"
  60 #include "close_on_fork.h"
  61 #include "net.h"
  62 #include "daemon.h"
  63 #include "ipc.h"
  64 #include "fd.h"
  65 #include "signal.h"
  66 #include "user_list.h"
  67 #include "color.h"
  68 #include "ggo.h"
  69 #include "version.h"
  70
  71 __printf_2_3 void (*para_log)(int, const char*, ...) = daemon_log;
  72
  73 /** Define the array of error lists needed by para_server. */
  74 INIT_SERVER_ERRLISTS;
  75
  76 /** Shut down non-authorized connections after that many seconds. */
  77 #define ALARM_TIMEOUT 10
  78
  79 /**
  80  * Pointer to shared memory area for communication between para_server
  81  * and its children. Exported to vss.c. command.c and to afs.
  82  */
  83 struct misc_meta_data *mmd;
  84
  85 /**
  86  * The configuration of para_server
  87  *
  88  * It also contains the options for the audio file selector, audio format
  89  * handler and all supported senders.
  90  */
  91 struct server_args_info conf;
  92
  93 /** A random value used in child context for authentication. */
  94 uint32_t afs_socket_cookie;
  95
  96 /** The mutex protecting the shared memory area containing the mmd struct. */
  97 int mmd_mutex;
  98
  99 /** The file containing user information (public key, permissions). */
 100 static char *user_list_file = NULL;
 101
 102 static struct sched sched;
 103
 104 /** The task responsible for server command handling. */
 105 struct server_command_task {
 106         /** TCP port on which para_server listens for connections. */
 107         int listen_fd;
 108         /** Copied from para_server's main function. */
 109         int argc;
 110         /** Argument vector passed to para_server's main function. */
 111         char **argv;
 112         /** The command task structure for scheduling. */
 113         struct task *task;
 114 };
 115
 116 /**
 117  * Return the list of tasks for the server process.
 118  *
 119  * This is called from \a com_tasks(). The helper is necessary since command
 120  * handlers can not access the scheduler structure directly.
 121  *
 122  * \return A dynamically allocated string that must be freed by the caller.
 123  */
 124 char *server_get_tasks(void)
 125 {
 126         return get_task_list(&sched);
 127 }
 128
 129 /*
 130  * setup shared memory area and get mutex for locking
 131  */
 132 static void init_ipc_or_die(void)
 133 {
 134         void *shm;
 135         int shmid, ret = shm_new(sizeof(struct misc_meta_data));
 136
 137         if (ret < 0)
 138                 goto err_out;
 139         shmid = ret;
 140         ret = shm_attach(shmid, ATTACH_RW, &shm);
 141         shm_destroy(shmid);
 142         if (ret < 0)
 143                 goto err_out;
 144         mmd = shm;
 145
 146         ret = mutex_new();
 147         if (ret < 0)
 148                 goto err_out;
 149         mmd_mutex = ret;
 150
 151         mmd->num_played = 0;
 152         mmd->num_commands = 0;
 153         mmd->events = 0;
 154         mmd->num_connects = 0;
 155         mmd->active_connections = 0;
 156         mmd->vss_status_flags = VSS_NEXT;
 157         mmd->new_vss_status_flags = VSS_NEXT;
 158         return;
 159 err_out:
 160         PARA_EMERG_LOG("%s\n", para_strerror(-ret));
 161         exit(EXIT_FAILURE);
 162 }
 163
 164 /**
 165  * (Re-)read the server configuration files.
 166  *
 167  * \param override Passed to gengetopt to activate the override feature.
 168  *
 169  * This function also re-opens the logfile and sets the global \a
 170  * user_list_file variable.
 171  */
 172 void parse_config_or_die(int override)
 173 {
 174         char *home = para_homedir();
 175         int ret;
 176         char *cf;
 177
 178         daemon_close_log();
 179         if (conf.config_file_given)
 180                 cf = para_strdup(conf.config_file_arg);
 181         else
 182                 cf = make_message("%s/.paraslash/server.conf", home);
 183         free(user_list_file);
 184         if (!conf.user_list_given)
 185                 user_list_file = make_message("%s/.paraslash/server.users", home);
 186         else
 187                 user_list_file = para_strdup(conf.user_list_arg);
 188         ret = file_exists(cf);
 189         if (conf.config_file_given && !ret)  {
 190                 ret = -1;
 191                 PARA_EMERG_LOG("can not read config file %s\n", cf);
 192                 goto out;
 193         }
 194         if (ret) {
 195                 int tmp = conf.daemon_given;
 196                 struct server_cmdline_parser_params params = {
 197                         .override = override,
 198                         .initialize = 0,
 199                         .check_required = 1,
 200                         .check_ambiguity = 0,
 201                         .print_errors = !conf.daemon_given
 202                 };
 203                 server_cmdline_parser_config_file(cf, &conf, &params);
 204                 daemon_set_loglevel(conf.loglevel_arg);
 205                 conf.daemon_given = tmp;
 206         }
 207         if (conf.logfile_given) {
 208                 daemon_set_logfile(conf.logfile_arg);
 209                 daemon_open_log_or_die();
 210         }
 211
 212         daemon_init_colors_or_die(conf.color_arg, color_arg_auto, color_arg_no,
 213                 conf.logfile_given, conf.log_color_arg, conf.log_color_given);
 214         daemon_set_flag(DF_LOG_PID);
 215         daemon_set_flag(DF_LOG_LL);
 216         daemon_set_flag(DF_LOG_TIME);
 217         if (conf.log_timing_given)
 218                 daemon_set_flag(DF_LOG_TIMING);
 219         ret = 1;
 220 out:
 221         free(cf);
 222         free(home);
 223         if (ret > 0)
 224                 return;
 225         free(user_list_file);
 226         user_list_file = NULL;
 227         exit(EXIT_FAILURE);
 228 }
 229
 230 static void signal_pre_select(struct sched *s, void *context)
 231 {
 232         struct signal_task *st = context;
 233         para_fd_set(st->fd, &s->rfds, &s->max_fileno);
 234 }
 235
 236 /*
 237  * called when server gets SIGHUP or when client invokes hup command.
 238  */
 239 static void handle_sighup(void)
 240 {
 241         PARA_NOTICE_LOG("SIGHUP\n");
 242         parse_config_or_die(1); /* reopens log */
 243         init_user_list(user_list_file); /* reload user list */
 244         if (mmd->afs_pid)
 245                 kill(mmd->afs_pid, SIGHUP);
 246 }
 247
 248 static int signal_post_select(struct sched *s, __a_unused void *context)
 249 {
 250         int signum = para_next_signal(&s->rfds);
 251
 252         switch (signum) {
 253         case 0:
 254                 return 0;
 255         case SIGHUP:
 256                 handle_sighup();
 257                 break;
 258         case SIGCHLD:
 259                 for (;;) {
 260                         pid_t pid;
 261                         int ret = para_reap_child(&pid);
 262                         if (ret <= 0)
 263                                 break;
 264                         if (pid != mmd->afs_pid)
 265                                 continue;
 266                         PARA_EMERG_LOG("fatal: afs died\n");
 267                         kill(0, SIGTERM);
 268                         goto cleanup;
 269                 }
 270                 break;
 271         /* die on sigint/sigterm. Kill all children too. */
 272         case SIGINT:
 273         case SIGTERM:
 274                 PARA_EMERG_LOG("terminating on signal %d\n", signum);
 275                 kill(0, SIGTERM);
 276                 /*
 277                  * We must wait for afs because afs catches SIGINT/SIGTERM.
 278                  * Before reacting to the signal, afs might want to use the
 279                  * shared memory area and the mmd mutex.  If we destroy this
 280                  * mutex too early and afs tries to lock the shared memory
 281                  * area, the call to mutex_lock() will fail and terminate the
 282                  * afs process. This leads to dirty osl tables.
 283                  *
 284                  * There's no such problem with the other children of the
 285                  * server process (the command handlers) as these reset their
 286                  * SIGINT/SIGTERM handlers to the default action, i.e.  these
 287                  * processes get killed immediately by the above kill().
 288                  */
 289                 PARA_INFO_LOG("waiting for afs (pid %d) to die\n",
 290                         (int)mmd->afs_pid);
 291                 waitpid(mmd->afs_pid, NULL, 0);
 292 cleanup:
 293                 free(mmd->afd.afhi.chunk_table);
 294                 close_listed_fds();
 295                 mutex_destroy(mmd_mutex);
 296                 shm_detach(mmd);
 297                 exit(EXIT_FAILURE);
 298         }
 299         return 0;
 300 }
 301
 302 static void init_signal_task(void)
 303 {
 304         static struct signal_task signal_task_struct,
 305                 *st = &signal_task_struct;
 306
 307         PARA_NOTICE_LOG("setting up signal handling\n");
 308         st->fd = para_signal_init(); /* always successful */
 309         para_install_sighandler(SIGINT);
 310         para_install_sighandler(SIGTERM);
 311         para_install_sighandler(SIGHUP);
 312         para_install_sighandler(SIGCHLD);
 313         para_sigaction(SIGPIPE, SIG_IGN);
 314         add_close_on_fork_list(st->fd);
 315         st->task = task_register(&(struct task_info) {
 316                 .name = "signal",
 317                 .pre_select = signal_pre_select,
 318                 .post_select = signal_post_select,
 319                 .context = st,
 320
 321         }, &sched);
 322 }
 323
 324 static void command_pre_select(struct sched *s, void *context)
 325 {
 326         struct server_command_task *sct = context;
 327         para_fd_set(sct->listen_fd, &s->rfds, &s->max_fileno);
 328 }
 329
 330 static int command_post_select(struct sched *s, void *context)
 331 {
 332         struct server_command_task *sct = context;
 333
 334         int new_fd, ret, i;
 335         char *peer_name;
 336         pid_t child_pid;
 337         uint32_t *chunk_table;
 338
 339         ret = para_accept(sct->listen_fd, &s->rfds, NULL, 0, &new_fd);
 340         if (ret <= 0)
 341                 goto out;
 342         peer_name = remote_name(new_fd);
 343         PARA_INFO_LOG("got connection from %s, forking\n", peer_name);
 344         mmd->num_connects++;
 345         mmd->active_connections++;
 346         /*
 347          * The chunk table is a pointer located in the mmd struct that points
 348          * to dynamically allocated memory, i.e. it must be freed by the parent
 349          * and the child. However, as the mmd struct is in a shared memory
 350          * area, there's no guarantee that after the fork this pointer is still
 351          * valid in child context. As it is not used in the child anyway, we
 352          * save it to a local variable before the fork and free the memory via
 353          * that copy in the child directly after the fork.
 354          */
 355         chunk_table = mmd->afd.afhi.chunk_table;
 356         child_pid = fork();
 357         if (child_pid < 0) {
 358                 ret = -ERRNO_TO_PARA_ERROR(errno);
 359                 goto out;
 360         }
 361         if (child_pid) {
 362                 /* avoid problems with non-fork-safe PRNGs */
 363                 unsigned char buf[16];
 364                 get_random_bytes_or_die(buf, sizeof(buf));
 365                 close(new_fd);
 366                 /* parent keeps accepting connections */
 367                 return 0;
 368         }
 369         /* mmd might already have changed at this point */
 370         free(chunk_table);
 371         alarm(ALARM_TIMEOUT);
 372         close_listed_fds();
 373         para_signal_shutdown();
 374         /*
 375          * put info on who we are serving into argv[0] to make
 376          * client ip visible in top/ps
 377          */
 378         for (i = sct->argc - 1; i >= 0; i--)
 379                 memset(sct->argv[i], 0, strlen(sct->argv[i]));
 380         sprintf(sct->argv[0], "para_server (serving %s)", peer_name);
 381         handle_connect(new_fd, peer_name);
 382         /* never reached*/
 383 out:
 384         if (ret < 0)
 385                 PARA_CRIT_LOG("%s\n", para_strerror(-ret));
 386         return 0;
 387 }
 388
 389 static void init_server_command_task(int argc, char **argv)
 390 {
 391         int ret;
 392         static struct server_command_task server_command_task_struct,
 393                 *sct = &server_command_task_struct;
 394
 395         PARA_NOTICE_LOG("initializing tcp command socket\n");
 396         sct->argc = argc;
 397         sct->argv = argv;
 398         ret = para_listen_simple(IPPROTO_TCP, conf.port_arg);
 399         if (ret < 0)
 400                 goto err;
 401         sct->listen_fd = ret;
 402         ret = mark_fd_nonblocking(sct->listen_fd);
 403         if (ret < 0)
 404                 goto err;
 405         add_close_on_fork_list(sct->listen_fd); /* child doesn't need the listener */
 406         sct->task = task_register(&(struct task_info) {
 407                 .name = "server command",
 408                 .pre_select = command_pre_select,
 409                 .post_select = command_post_select,
 410                 .context = sct,
 411         }, &sched);
 412         return;
 413 err:
 414         PARA_EMERG_LOG("%s\n", para_strerror(-ret));
 415         exit(EXIT_FAILURE);
 416 }
 417
 418 static int init_afs(int argc, char **argv)
 419 {
 420         int ret, afs_server_socket[2];
 421         pid_t afs_pid;
 422
 423         ret = socketpair(PF_UNIX, SOCK_DGRAM, 0, afs_server_socket);
 424         if (ret < 0)
 425                 exit(EXIT_FAILURE);
 426         get_random_bytes_or_die((unsigned char *)&afs_socket_cookie,
 427                 sizeof(afs_socket_cookie));
 428         afs_pid = fork();
 429         if (afs_pid < 0)
 430                 exit(EXIT_FAILURE);
 431         if (afs_pid == 0) { /* child (afs) */
 432                 int i;
 433                 for (i = argc - 1; i >= 0; i--)
 434                         memset(argv[i], 0, strlen(argv[i]));
 435                 sprintf(argv[0], "para_server (afs)");
 436                 close(afs_server_socket[0]);
 437                 afs_init(afs_socket_cookie, afs_server_socket[1]);
 438         }
 439         mmd->afs_pid = afs_pid;
 440         close(afs_server_socket[1]);
 441         ret = mark_fd_nonblocking(afs_server_socket[0]);
 442         if (ret < 0)
 443                 exit(EXIT_FAILURE);
 444         add_close_on_fork_list(afs_server_socket[0]);
 445         PARA_INFO_LOG("afs_socket: %d, afs_socket_cookie: %u\n",
 446                 afs_server_socket[0], (unsigned) afs_socket_cookie);
 447         return afs_server_socket[0];
 448 }
 449
 450 __noreturn static void print_help_and_die(void)
 451 {
 452         struct ggo_help h = DEFINE_GGO_HELP(server);
 453         bool d = conf.detailed_help_given;
 454
 455         ggo_print_help(&h, d? GPH_STANDARD_FLAGS_DETAILED : GPH_STANDARD_FLAGS);
 456         exit(0);
 457 }
 458
 459 static void server_init(int argc, char **argv)
 460 {
 461         struct server_cmdline_parser_params params = {
 462                 .override = 0,
 463                 .initialize = 1,
 464                 .check_required = 0,
 465                 .check_ambiguity = 0,
 466                 .print_errors = 1
 467         };
 468         int afs_socket;
 469
 470         valid_fd_012();
 471         init_random_seed_or_die();
 472         /* parse command line options */
 473         server_cmdline_parser_ext(argc, argv, &conf, &params);
 474         daemon_set_loglevel(conf.loglevel_arg);
 475         version_handle_flag("server", conf.version_given);
 476         if (conf.help_given || conf.detailed_help_given)
 477                 print_help_and_die();
 478         daemon_drop_privileges_or_die(conf.user_arg, conf.group_arg);
 479         /* parse config file, open log and set defaults */
 480         parse_config_or_die(0);
 481         daemon_log_welcome("para_server");
 482         init_ipc_or_die(); /* init mmd struct and mmd->lock */
 483         daemon_set_start_time();
 484         init_user_list(user_list_file);
 485         /* become daemon */
 486         if (conf.daemon_given)
 487                 daemonize(true /* parent waits for SIGTERM */);
 488         PARA_NOTICE_LOG("initializing audio format handlers\n");
 489         afh_init();
 490
 491         /*
 492          * Although afs uses its own signal handling we must ignore SIGUSR1
 493          * _before_ the afs child process gets born by init_afs() below.  It's
 494          * racy to do this in the child because the parent might send SIGUSR1
 495          * before the child gets a chance to ignore this signal -- only the
 496          * good die young.
 497          */
 498         para_sigaction(SIGUSR1, SIG_IGN);
 499         /*
 500          * We have to block SIGCHLD before the afs process is being forked off.
 501          * Otherwise, para_server does not notice if afs dies before the
 502          * SIGCHLD handler has been installed for the parent process by
 503          * init_signal_task() below.
 504          */
 505         para_block_signal(SIGCHLD);
 506         PARA_NOTICE_LOG("initializing the audio file selector\n");
 507         afs_socket = init_afs(argc, argv);
 508         init_signal_task();
 509         para_unblock_signal(SIGCHLD);
 510         PARA_NOTICE_LOG("initializing virtual streaming system\n");
 511         init_vss_task(afs_socket, &sched);
 512         init_server_command_task(argc, argv);
 513         if (conf.daemon_given)
 514                 kill(getppid(), SIGTERM);
 515         PARA_NOTICE_LOG("server init complete\n");
 516 }
 517
 518 static void status_refresh(void)
 519 {
 520         static int prev_uptime = -1, prev_events = -1;
 521         int uptime = daemon_get_uptime(now);
 522
 523         if (prev_events != mmd->events)
 524                 goto out;
 525         if (mmd->new_vss_status_flags != mmd->vss_status_flags)
 526                 goto out_inc_events;
 527         if (uptime / 60 != prev_uptime / 60)
 528                 goto out_inc_events;
 529         return;
 530 out_inc_events:
 531         mmd->events++;
 532 out:
 533         prev_uptime = uptime;
 534         prev_events = mmd->events;
 535         mmd->vss_status_flags = mmd->new_vss_status_flags;
 536         PARA_DEBUG_LOG("%d events, forcing status update\n", mmd->events);
 537         killpg(0, SIGUSR1);
 538 }
 539
 540 static int server_select(int max_fileno, fd_set *readfds, fd_set *writefds,
 541                 struct timeval *timeout_tv)
 542 {
 543         int ret;
 544
 545         status_refresh();
 546         mutex_unlock(mmd_mutex);
 547         ret = para_select(max_fileno + 1, readfds, writefds, timeout_tv);
 548         mutex_lock(mmd_mutex);
 549         return ret;
 550 }
 551
 552 /**
 553  * The main function of para_server.
 554  *
 555  * \param argc Usual argument count.
 556  * \param argv Usual argument vector.
 557  *
 558  * \return EXIT_SUCCESS or EXIT_FAILURE.
 559  */
 560 int main(int argc, char *argv[])
 561 {
 562         int ret;
 563
 564         sched.default_timeout.tv_sec = 1;
 565         sched.select_function = server_select;
 566
 567         server_init(argc, argv);
 568         mutex_lock(mmd_mutex);
 569         ret = schedule(&sched);
 570         sched_shutdown(&sched);
 571         if (ret < 0) {
 572                 PARA_EMERG_LOG("%s\n", para_strerror(-ret));
 573                 exit(EXIT_FAILURE);
 574         }
 575         exit(EXIT_SUCCESS);
 576 }