server.c

   1 /*
   2  * Copyright (C) 1997-2014 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  * \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 static int want_colors(void)
 117 {
 118         if (conf.color_arg == color_arg_no)
 119                 return 0;
 120         if (conf.color_arg == color_arg_yes)
 121                 return 1;
 122         if (conf.logfile_given)
 123                 return 0;
 124         return isatty(STDERR_FILENO);
 125 }
 126
 127 static void init_colors_or_die(void)
 128 {
 129         int i;
 130
 131         if (!want_colors())
 132                 return;
 133         daemon_set_flag(DF_COLOR_LOG);
 134         daemon_set_default_log_colors();
 135         for (i = 0; i < conf.log_color_given; i++)
 136                 daemon_set_log_color_or_die(conf.log_color_arg[i]);
 137 }
 138
 139 /*
 140  * setup shared memory area and get mutex for locking
 141  */
 142 static void init_ipc_or_die(void)
 143 {
 144         void *shm;
 145         int shmid, ret = shm_new(sizeof(struct misc_meta_data));
 146
 147         if (ret < 0)
 148                 goto err_out;
 149         shmid = ret;
 150         ret = shm_attach(shmid, ATTACH_RW, &shm);
 151         shm_destroy(shmid);
 152         if (ret < 0)
 153                 goto err_out;
 154         mmd = shm;
 155
 156         ret = mutex_new();
 157         if (ret < 0)
 158                 goto err_out;
 159         mmd_mutex = ret;
 160
 161         mmd->num_played = 0;
 162         mmd->num_commands = 0;
 163         mmd->events = 0;
 164         mmd->num_connects = 0;
 165         mmd->active_connections = 0;
 166         mmd->vss_status_flags = VSS_NEXT;
 167         mmd->new_vss_status_flags = VSS_NEXT;
 168         return;
 169 err_out:
 170         PARA_EMERG_LOG("%s\n", para_strerror(-ret));
 171         exit(EXIT_FAILURE);
 172 }
 173
 174 /**
 175  * (Re-)read the server configuration files.
 176  *
 177  * \param override Passed to gengetopt to activate the override feature.
 178  *
 179  * This function also re-opens the logfile and sets the global \a
 180  * user_list_file variable.
 181  */
 182 void parse_config_or_die(int override)
 183 {
 184         char *home = para_homedir();
 185         int ret;
 186         char *cf;
 187
 188         daemon_close_log();
 189         if (conf.config_file_given)
 190                 cf = para_strdup(conf.config_file_arg);
 191         else
 192                 cf = make_message("%s/.paraslash/server.conf", home);
 193         free(user_list_file);
 194         if (!conf.user_list_given)
 195                 user_list_file = make_message("%s/.paraslash/server.users", home);
 196         else
 197                 user_list_file = para_strdup(conf.user_list_arg);
 198         ret = file_exists(cf);
 199         if (conf.config_file_given && !ret)  {
 200                 ret = -1;
 201                 PARA_EMERG_LOG("can not read config file %s\n", cf);
 202                 goto out;
 203         }
 204         if (ret) {
 205                 int tmp = conf.daemon_given;
 206                 struct server_cmdline_parser_params params = {
 207                         .override = override,
 208                         .initialize = 0,
 209                         .check_required = 1,
 210                         .check_ambiguity = 0,
 211                         .print_errors = !conf.daemon_given
 212                 };
 213                 server_cmdline_parser_config_file(cf, &conf, &params);
 214                 daemon_set_loglevel(conf.loglevel_arg);
 215                 conf.daemon_given = tmp;
 216         }
 217         if (conf.logfile_given) {
 218                 daemon_set_logfile(conf.logfile_arg);
 219                 daemon_open_log_or_die();
 220         }
 221         init_colors_or_die();
 222         daemon_set_flag(DF_LOG_PID);
 223         daemon_set_flag(DF_LOG_LL);
 224         daemon_set_flag(DF_LOG_TIME);
 225         if (conf.log_timing_given)
 226                 daemon_set_flag(DF_LOG_TIMING);
 227         ret = 1;
 228 out:
 229         free(cf);
 230         free(home);
 231         if (ret > 0)
 232                 return;
 233         free(user_list_file);
 234         user_list_file = NULL;
 235         exit(EXIT_FAILURE);
 236 }
 237
 238 static void signal_pre_select(struct sched *s, void *context)
 239 {
 240         struct signal_task *st = context;
 241         para_fd_set(st->fd, &s->rfds, &s->max_fileno);
 242 }
 243
 244 /*
 245  * called when server gets SIGHUP or when client invokes hup command.
 246  */
 247 static void handle_sighup(void)
 248 {
 249         PARA_NOTICE_LOG("SIGHUP\n");
 250         parse_config_or_die(1); /* reopens log */
 251         init_user_list(user_list_file); /* reload user list */
 252         if (mmd->afs_pid)
 253                 kill(mmd->afs_pid, SIGHUP);
 254 }
 255
 256 static int signal_post_select(struct sched *s, __a_unused void *context)
 257 {
 258         int signum = para_next_signal(&s->rfds);
 259
 260         switch (signum) {
 261         case 0:
 262                 return 0;
 263         case SIGHUP:
 264                 handle_sighup();
 265                 break;
 266         case SIGCHLD:
 267                 for (;;) {
 268                         pid_t pid;
 269                         int ret = para_reap_child(&pid);
 270                         if (ret <= 0)
 271                                 break;
 272                         if (pid != mmd->afs_pid)
 273                                 continue;
 274                         PARA_EMERG_LOG("fatal: afs died\n");
 275                         kill(0, SIGTERM);
 276                         goto cleanup;
 277                 }
 278                 break;
 279         /* die on sigint/sigterm. Kill all children too. */
 280         case SIGINT:
 281         case SIGTERM:
 282                 PARA_EMERG_LOG("terminating on signal %d\n", signum);
 283                 kill(0, SIGTERM);
 284                 /*
 285                  * We must wait for afs because afs catches SIGINT/SIGTERM.
 286                  * Before reacting to the signal, afs might want to use the
 287                  * shared memory area and the mmd mutex.  If we destroy this
 288                  * mutex too early and afs tries to lock the shared memory
 289                  * area, the call to mutex_lock() will fail and terminate the
 290                  * afs process. This leads to dirty osl tables.
 291                  *
 292                  * There's no such problem with the other children of the
 293                  * server process (the command handlers) as these reset their
 294                  * SIGINT/SIGTERM handlers to the default action, i.e.  these
 295                  * processes get killed immediately by the above kill().
 296                  */
 297                 PARA_INFO_LOG("waiting for afs (pid %d) to die\n",
 298                         (int)mmd->afs_pid);
 299                 waitpid(mmd->afs_pid, NULL, 0);
 300 cleanup:
 301                 free(mmd->afd.afhi.chunk_table);
 302                 close_listed_fds();
 303                 mutex_destroy(mmd_mutex);
 304                 shm_detach(mmd);
 305                 exit(EXIT_FAILURE);
 306         }
 307         return 0;
 308 }
 309
 310 static void init_signal_task(void)
 311 {
 312         static struct signal_task signal_task_struct,
 313                 *st = &signal_task_struct;
 314
 315         PARA_NOTICE_LOG("setting up signal handling\n");
 316         st->fd = para_signal_init(); /* always successful */
 317         para_install_sighandler(SIGINT);
 318         para_install_sighandler(SIGTERM);
 319         para_install_sighandler(SIGHUP);
 320         para_install_sighandler(SIGCHLD);
 321         para_sigaction(SIGPIPE, SIG_IGN);
 322         add_close_on_fork_list(st->fd);
 323         st->task = task_register(&(struct task_info) {
 324                 .name = "signal",
 325                 .pre_select = signal_pre_select,
 326                 .post_select = signal_post_select,
 327                 .context = st,
 328
 329         }, &sched);
 330 }
 331
 332 static void command_pre_select(struct sched *s, void *context)
 333 {
 334         struct server_command_task *sct = context;
 335         para_fd_set(sct->listen_fd, &s->rfds, &s->max_fileno);
 336 }
 337
 338 static int command_post_select(struct sched *s, void *context)
 339 {
 340         struct server_command_task *sct = context;
 341
 342         int new_fd, ret, i;
 343         char *peer_name;
 344         pid_t child_pid;
 345         uint32_t *chunk_table;
 346
 347         ret = para_accept(sct->listen_fd, &s->rfds, NULL, 0, &new_fd);
 348         if (ret <= 0)
 349                 goto out;
 350         peer_name = remote_name(new_fd);
 351         PARA_INFO_LOG("got connection from %s, forking\n", peer_name);
 352         mmd->num_connects++;
 353         mmd->active_connections++;
 354         /*
 355          * The chunk table is a pointer located in the mmd struct that points
 356          * to dynamically allocated memory, i.e. it must be freed by the parent
 357          * and the child. However, as the mmd struct is in a shared memory
 358          * area, there's no guarantee that after the fork this pointer is still
 359          * valid in child context. As it is not used in the child anyway, we
 360          * save it to a local variable before the fork and free the memory via
 361          * that copy in the child directly after the fork.
 362          */
 363         chunk_table = mmd->afd.afhi.chunk_table;
 364         child_pid = fork();
 365         if (child_pid < 0) {
 366                 ret = -ERRNO_TO_PARA_ERROR(errno);
 367                 goto out;
 368         }
 369         if (child_pid) {
 370                 /* avoid problems with non-fork-safe PRNGs */
 371                 unsigned char buf[16];
 372                 get_random_bytes_or_die(buf, sizeof(buf));
 373                 close(new_fd);
 374                 /* parent keeps accepting connections */
 375                 return 0;
 376         }
 377         /* mmd might already have changed at this point */
 378         free(chunk_table);
 379         alarm(ALARM_TIMEOUT);
 380         close_listed_fds();
 381         para_signal_shutdown();
 382         /*
 383          * put info on who we are serving into argv[0] to make
 384          * client ip visible in top/ps
 385          */
 386         for (i = sct->argc - 1; i >= 0; i--)
 387                 memset(sct->argv[i], 0, strlen(sct->argv[i]));
 388         sprintf(sct->argv[0], "para_server (serving %s)", peer_name);
 389         handle_connect(new_fd, peer_name);
 390         /* never reached*/
 391 out:
 392         if (ret < 0)
 393                 PARA_CRIT_LOG("%s\n", para_strerror(-ret));
 394         return 0;
 395 }
 396
 397 static void init_server_command_task(int argc, char **argv)
 398 {
 399         int ret;
 400         static struct server_command_task server_command_task_struct,
 401                 *sct = &server_command_task_struct;
 402
 403         PARA_NOTICE_LOG("initializing tcp command socket\n");
 404         sct->argc = argc;
 405         sct->argv = argv;
 406         ret = para_listen_simple(IPPROTO_TCP, conf.port_arg);
 407         if (ret < 0)
 408                 goto err;
 409         sct->listen_fd = ret;
 410         ret = mark_fd_nonblocking(sct->listen_fd);
 411         if (ret < 0)
 412                 goto err;
 413         add_close_on_fork_list(sct->listen_fd); /* child doesn't need the listener */
 414         sct->task = task_register(&(struct task_info) {
 415                 .name = "server command",
 416                 .pre_select = command_pre_select,
 417                 .post_select = command_post_select,
 418                 .context = sct,
 419         }, &sched);
 420         return;
 421 err:
 422         PARA_EMERG_LOG("%s\n", para_strerror(-ret));
 423         exit(EXIT_FAILURE);
 424 }
 425
 426 static int init_afs(int argc, char **argv)
 427 {
 428         int ret, afs_server_socket[2];
 429         pid_t afs_pid;
 430
 431         ret = socketpair(PF_UNIX, SOCK_DGRAM, 0, afs_server_socket);
 432         if (ret < 0)
 433                 exit(EXIT_FAILURE);
 434         get_random_bytes_or_die((unsigned char *)&afs_socket_cookie,
 435                 sizeof(afs_socket_cookie));
 436         afs_pid = fork();
 437         if (afs_pid < 0)
 438                 exit(EXIT_FAILURE);
 439         if (afs_pid == 0) { /* child (afs) */
 440                 int i;
 441                 for (i = argc - 1; i >= 0; i--)
 442                         memset(argv[i], 0, strlen(argv[i]));
 443                 sprintf(argv[0], "para_server (afs)");
 444                 close(afs_server_socket[0]);
 445                 afs_init(afs_socket_cookie, afs_server_socket[1]);
 446         }
 447         mmd->afs_pid = afs_pid;
 448         close(afs_server_socket[1]);
 449         ret = mark_fd_nonblocking(afs_server_socket[0]);
 450         if (ret < 0)
 451                 exit(EXIT_FAILURE);
 452         add_close_on_fork_list(afs_server_socket[0]);
 453         PARA_INFO_LOG("afs_socket: %d, afs_socket_cookie: %u\n",
 454                 afs_server_socket[0], (unsigned) afs_socket_cookie);
 455         return afs_server_socket[0];
 456 }
 457
 458 __noreturn static void print_help_and_die(void)
 459 {
 460         struct ggo_help h = DEFINE_GGO_HELP(server);
 461         bool d = conf.detailed_help_given;
 462
 463         ggo_print_help(&h, d? GPH_STANDARD_FLAGS_DETAILED : GPH_STANDARD_FLAGS);
 464         exit(0);
 465 }
 466
 467 static void server_init(int argc, char **argv)
 468 {
 469         struct server_cmdline_parser_params params = {
 470                 .override = 0,
 471                 .initialize = 1,
 472                 .check_required = 0,
 473                 .check_ambiguity = 0,
 474                 .print_errors = 1
 475         };
 476         int afs_socket;
 477
 478         valid_fd_012();
 479         init_random_seed_or_die();
 480         /* parse command line options */
 481         server_cmdline_parser_ext(argc, argv, &conf, &params);
 482         daemon_set_loglevel(conf.loglevel_arg);
 483         version_handle_flag("server", conf.version_given);
 484         if (conf.help_given || conf.detailed_help_given)
 485                 print_help_and_die();
 486         drop_privileges_or_die(conf.user_arg, conf.group_arg);
 487         /* parse config file, open log and set defaults */
 488         parse_config_or_die(0);
 489         log_welcome("para_server");
 490         init_ipc_or_die(); /* init mmd struct and mmd->lock */
 491         /* make sure, the global now pointer is uptodate */
 492         clock_get_realtime(now);
 493         set_server_start_time(now);
 494         init_user_list(user_list_file);
 495         /* become daemon */
 496         if (conf.daemon_given)
 497                 daemonize(true /* parent waits for SIGTERM */);
 498         PARA_NOTICE_LOG("initializing audio format handlers\n");
 499         afh_init();
 500
 501         /*
 502          * Although afs uses its own signal handling we must ignore SIGUSR1
 503          * _before_ the afs child process gets born by init_afs() below.  It's
 504          * racy to do this in the child because the parent might send SIGUSR1
 505          * before the child gets a chance to ignore this signal -- only the
 506          * good die young.
 507          */
 508         para_sigaction(SIGUSR1, SIG_IGN);
 509         /*
 510          * We have to block SIGCHLD before the afs process is being forked off.
 511          * Otherwise, para_server does not notice if afs dies before the
 512          * SIGCHLD handler has been installed for the parent process by
 513          * init_signal_task() below.
 514          */
 515         para_block_signal(SIGCHLD);
 516         PARA_NOTICE_LOG("initializing the audio file selector\n");
 517         afs_socket = init_afs(argc, argv);
 518         init_signal_task();
 519         para_unblock_signal(SIGCHLD);
 520         PARA_NOTICE_LOG("initializing virtual streaming system\n");
 521         init_vss_task(afs_socket, &sched);
 522         init_server_command_task(argc, argv);
 523         if (conf.daemon_given)
 524                 kill(getppid(), SIGTERM);
 525         PARA_NOTICE_LOG("server init complete\n");
 526 }
 527
 528 static void status_refresh(void)
 529 {
 530         static int prev_uptime = -1, prev_events = -1;
 531         int uptime = get_server_uptime(now);
 532
 533         if (prev_events != mmd->events)
 534                 goto out;
 535         if (mmd->new_vss_status_flags != mmd->vss_status_flags)
 536                 goto out_inc_events;
 537         if (uptime / 60 != prev_uptime / 60)
 538                 goto out_inc_events;
 539         return;
 540 out_inc_events:
 541         mmd->events++;
 542 out:
 543         prev_uptime = uptime;
 544         prev_events = mmd->events;
 545         mmd->vss_status_flags = mmd->new_vss_status_flags;
 546         PARA_DEBUG_LOG("%d events, forcing status update\n", mmd->events);
 547         killpg(0, SIGUSR1);
 548 }
 549
 550 static int server_select(int max_fileno, fd_set *readfds, fd_set *writefds,
 551                 struct timeval *timeout_tv)
 552 {
 553         int ret;
 554
 555         status_refresh();
 556         mutex_unlock(mmd_mutex);
 557         ret = para_select(max_fileno + 1, readfds, writefds, timeout_tv);
 558         mutex_lock(mmd_mutex);
 559         return ret;
 560 }
 561
 562 /**
 563  * The main function of para_server.
 564  *
 565  * \param argc Usual argument count.
 566  * \param argv Usual argument vector.
 567  *
 568  * \return EXIT_SUCCESS or EXIT_FAILURE.
 569  */
 570 int main(int argc, char *argv[])
 571 {
 572         int ret;
 573
 574         sched.default_timeout.tv_sec = 1;
 575         sched.select_function = server_select;
 576
 577         server_init(argc, argv);
 578         mutex_lock(mmd_mutex);
 579         ret = schedule(&sched);
 580         sched_shutdown(&sched);
 581         if (ret < 0) {
 582                 PARA_EMERG_LOG("%s\n", para_strerror(-ret));
 583                 exit(EXIT_FAILURE);
 584         }
 585         exit(EXIT_SUCCESS);
 586 }