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 and selected APIs:
  11  *
  12  *      - Senders: \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  *      - Scheduling: \ref sched.h,
  18  *      - Buffer trees: \ref buffer_tree.h,
  19  *      - Sideband API: \ref sideband.h,
  20  *      - Crypto: \ref crypt.h, \ref crypt_backend.h,
  21  *      - Error subsystem: \ref error.h,
  22  *      - Inter process communication: \ref ipc.h,
  23  *      - Forward error correction: \ref fec.h,
  24  *      - Daemons: \ref daemon.h,
  25  *      - Mixer API: \ref mix.h,
  26  *      - Interactive sessions: \ref interactive.h,
  27  *      - File descriptors: \ref fd.h,
  28  *      - Signals: \ref signal.h,
  29  *      - Networking: \ref net.h,
  30  *      - Time: \ref time.c,
  31  *      - Doubly linked lists: \ref list.h.
  32  */
  33
  34 #include <netinet/in.h>
  35 #include <sys/socket.h>
  36 #include <signal.h>
  37 #include <regex.h>
  38 #include <osl.h>
  39 #include <sys/types.h>
  40 #include <arpa/inet.h>
  41 #include <sys/un.h>
  42 #include <netdb.h>
  43 #include <lopsub.h>
  44
  45 #include "server.lsg.h"
  46 #include "para.h"
  47 #include "error.h"
  48 #include "crypt.h"
  49 #include "afh.h"
  50 #include "string.h"
  51 #include "afs.h"
  52 #include "server.h"
  53 #include "list.h"
  54 #include "send.h"
  55 #include "sched.h"
  56 #include "vss.h"
  57 #include "config.h"
  58 #include "close_on_fork.h"
  59 #include "net.h"
  60 #include "daemon.h"
  61 #include "ipc.h"
  62 #include "fd.h"
  63 #include "signal.h"
  64 #include "user_list.h"
  65 #include "color.h"
  66 #include "version.h"
  67
  68 /** Array of error strings. */
  69 DEFINE_PARA_ERRLIST;
  70
  71 __printf_2_3 void (*para_log)(int, const char*, ...) = daemon_log;
  72
  73 /** Shut down non-authorized connections after that many seconds. */
  74 #define ALARM_TIMEOUT 10
  75
  76 /**
  77  * Pointer to shared memory area for communication between para_server
  78  * and its children. Exported to vss.c, command.c and to afs.
  79  */
  80 struct misc_meta_data *mmd;
  81
  82 /**
  83  * The active value for all config options of para_server.
  84  *
  85  * It is computed by merging the parse result of the command line options with
  86  * the parse result of the config file.
  87  */
  88 struct lls_parse_result *server_lpr = NULL;
  89
  90 /* Command line options (no config file options). Used in handle_sighup(). */
  91 static struct lls_parse_result *cmdline_lpr;
  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 static struct sched sched;
 100 static struct signal_task *signal_task;
 101
 102 /** The task responsible for server command handling. */
 103 struct server_command_task {
 104         /** TCP port on which para_server listens for connections. */
 105         int listen_fd;
 106         /** Copied from para_server's main function. */
 107         int argc;
 108         /** Argument vector passed to para_server's main function. */
 109         char **argv;
 110         /** The command task structure for scheduling. */
 111         struct task *task;
 112 };
 113
 114 /**
 115  * Return the list of tasks for the server process.
 116  *
 117  * This is called from \a com_tasks(). The helper is necessary since command
 118  * handlers can not access the scheduler structure directly.
 119  *
 120  * \return A dynamically allocated string that must be freed by the caller.
 121  */
 122 char *server_get_tasks(void)
 123 {
 124         return get_task_list(&sched);
 125 }
 126
 127 /*
 128  * setup shared memory area and get mutex for locking
 129  */
 130 static void init_ipc_or_die(void)
 131 {
 132         void *shm;
 133         int shmid, ret = shm_new(sizeof(struct misc_meta_data));
 134
 135         if (ret < 0)
 136                 goto err_out;
 137         shmid = ret;
 138         ret = shm_attach(shmid, ATTACH_RW, &shm);
 139         shm_destroy(shmid);
 140         if (ret < 0)
 141                 goto err_out;
 142         mmd = shm;
 143
 144         ret = mutex_new();
 145         if (ret < 0)
 146                 goto err_out;
 147         mmd_mutex = ret;
 148
 149         mmd->num_played = 0;
 150         mmd->num_commands = 0;
 151         mmd->events = 0;
 152         mmd->num_connects = 0;
 153         mmd->active_connections = 0;
 154         mmd->vss_status_flags = VSS_NEXT;
 155         mmd->new_vss_status_flags = VSS_NEXT;
 156         return;
 157 err_out:
 158         PARA_EMERG_LOG("%s\n", para_strerror(-ret));
 159         exit(EXIT_FAILURE);
 160 }
 161
 162 /**
 163  * (Re-)read the server configuration files.
 164  *
 165  * \param reload Whether config file overrides command line.
 166  *
 167  * This function also re-opens the logfile and the user list. On SIGHUP it is
 168  * called from both server and afs context.
 169  */
 170 void parse_config_or_die(bool reload)
 171 {
 172         int ret;
 173         char *cf = NULL, *errctx = NULL, *user_list_file = NULL;
 174         void *map;
 175         size_t sz;
 176         int cf_argc;
 177         char **cf_argv;
 178         struct lls_parse_result *cf_lpr, *merged_lpr;
 179         char *home = para_homedir();
 180
 181         daemon_close_log();
 182         if (OPT_GIVEN(CONFIG_FILE))
 183                 cf = para_strdup(OPT_STRING_VAL(CONFIG_FILE));
 184         else
 185                 cf = make_message("%s/.paraslash/server.conf", home);
 186         if (!mmd || getpid() != mmd->afs_pid) {
 187                 if (OPT_GIVEN(USER_LIST))
 188                         user_list_file = para_strdup(OPT_STRING_VAL(USER_LIST));
 189                 else
 190                         user_list_file = make_message("%s/.paraslash/server.users", home);
 191         }
 192         free(home);
 193         ret = mmap_full_file(cf, O_RDONLY, &map, &sz, NULL);
 194         if (ret < 0) {
 195                 if (ret != -E_EMPTY && ret != -ERRNO_TO_PARA_ERROR(ENOENT))
 196                         goto free_cf;
 197                 if (ret == -ERRNO_TO_PARA_ERROR(ENOENT) && OPT_GIVEN(CONFIG_FILE))
 198                         goto free_cf;
 199                 ret = 0;
 200                 server_lpr = cmdline_lpr;
 201                 goto success;
 202         }
 203         ret = lls(lls_convert_config(map, sz, NULL, &cf_argv, &errctx));
 204         para_munmap(map, sz);
 205         if (ret < 0)
 206                 goto free_cf;
 207         cf_argc = ret;
 208         ret = lls(lls_parse(cf_argc, cf_argv, CMD_PTR, &cf_lpr, &errctx));
 209         lls_free_argv(cf_argv);
 210         if (ret < 0)
 211                 goto free_cf;
 212         if (reload) /* config file overrides command line */
 213                 ret = lls(lls_merge(cf_lpr, cmdline_lpr, CMD_PTR, &merged_lpr,
 214                         &errctx));
 215         else /* command line options overrride config file options */
 216                 ret = lls(lls_merge(cmdline_lpr, cf_lpr, CMD_PTR, &merged_lpr,
 217                         &errctx));
 218         lls_free_parse_result(cf_lpr, CMD_PTR);
 219         if (ret < 0)
 220                 goto free_cf;
 221         if (server_lpr != cmdline_lpr)
 222                 lls_free_parse_result(server_lpr, CMD_PTR);
 223         server_lpr = merged_lpr;
 224 success:
 225         daemon_set_loglevel(ENUM_STRING_VAL(LOGLEVEL));
 226         if (OPT_GIVEN(LOGFILE)) {
 227                 daemon_set_logfile(OPT_STRING_VAL(LOGFILE));
 228                 daemon_open_log_or_die();
 229         }
 230         if (daemon_init_colors_or_die(OPT_UINT32_VAL(COLOR), COLOR_AUTO,
 231                         COLOR_NO, OPT_GIVEN(LOGFILE))) {
 232                 int i;
 233                 for (i = 0; i < OPT_GIVEN(LOG_COLOR); i++)
 234                         daemon_set_log_color_or_die(lls_string_val(i,
 235                                 OPT_RESULT(LOG_COLOR)));
 236         }
 237         daemon_set_flag(DF_LOG_PID);
 238         daemon_set_flag(DF_LOG_LL);
 239         daemon_set_flag(DF_LOG_TIME);
 240         if (OPT_GIVEN(LOG_TIMING))
 241                 daemon_set_flag(DF_LOG_TIMING);
 242         daemon_set_priority(OPT_UINT32_VAL(PRIORITY));
 243         if (user_list_file)
 244                 init_user_list(user_list_file);
 245         ret = 1;
 246 free_cf:
 247         free(cf);
 248         free(user_list_file);
 249         if (ret < 0) {
 250                 if (errctx)
 251                         PARA_ERROR_LOG("%s\n", errctx);
 252                 free(errctx);
 253                 PARA_EMERG_LOG("%s\n", para_strerror(-ret));
 254                 exit(EXIT_FAILURE);
 255         }
 256 }
 257
 258 /*
 259  * called when server gets SIGHUP or when client invokes hup command.
 260  */
 261 static void handle_sighup(void)
 262 {
 263
 264         PARA_NOTICE_LOG("SIGHUP\n");
 265         parse_config_or_die(true);
 266         if (mmd->afs_pid)
 267                 kill(mmd->afs_pid, SIGHUP);
 268 }
 269
 270 static int signal_post_select(struct sched *s, __a_unused void *context)
 271 {
 272         int signum = para_next_signal(&s->rfds);
 273
 274         switch (signum) {
 275         case 0:
 276                 return 0;
 277         case SIGHUP:
 278                 handle_sighup();
 279                 break;
 280         case SIGCHLD:
 281                 for (;;) {
 282                         pid_t pid;
 283                         int ret = para_reap_child(&pid);
 284                         if (ret <= 0)
 285                                 break;
 286                         if (pid != mmd->afs_pid)
 287                                 continue;
 288                         PARA_EMERG_LOG("fatal: afs died\n");
 289                         kill(0, SIGTERM);
 290                         goto cleanup;
 291                 }
 292                 break;
 293         /* die on sigint/sigterm. Kill all children too. */
 294         case SIGINT:
 295         case SIGTERM:
 296                 PARA_EMERG_LOG("terminating on signal %d\n", signum);
 297                 kill(0, SIGTERM);
 298                 /*
 299                  * We must wait for afs because afs catches SIGINT/SIGTERM.
 300                  * Before reacting to the signal, afs might want to use the
 301                  * shared memory area and the mmd mutex.  If we destroy this
 302                  * mutex too early and afs tries to lock the shared memory
 303                  * area, the call to mutex_lock() will fail and terminate the
 304                  * afs process. This leads to dirty osl tables.
 305                  *
 306                  * There's no such problem with the other children of the
 307                  * server process (the command handlers) as these reset their
 308                  * SIGINT/SIGTERM handlers to the default action, i.e.  these
 309                  * processes get killed immediately by the above kill().
 310                  */
 311                 PARA_INFO_LOG("waiting for afs (pid %d) to die\n",
 312                         (int)mmd->afs_pid);
 313                 waitpid(mmd->afs_pid, NULL, 0);
 314 cleanup:
 315                 free(mmd->afd.afhi.chunk_table);
 316                 close_listed_fds();
 317                 mutex_destroy(mmd_mutex);
 318                 shm_detach(mmd);
 319                 exit(EXIT_FAILURE);
 320         }
 321         return 0;
 322 }
 323
 324 static void init_signal_task(void)
 325 {
 326         signal_task = signal_init_or_die();
 327         para_install_sighandler(SIGINT);
 328         para_install_sighandler(SIGTERM);
 329         para_install_sighandler(SIGHUP);
 330         para_install_sighandler(SIGCHLD);
 331         para_sigaction(SIGPIPE, SIG_IGN);
 332         add_close_on_fork_list(signal_task->fd);
 333         signal_task->task = task_register(&(struct task_info) {
 334                 .name = "signal",
 335                 .pre_select = signal_pre_select,
 336                 .post_select = signal_post_select,
 337                 .context = signal_task,
 338
 339         }, &sched);
 340 }
 341
 342 static void command_pre_select(struct sched *s, void *context)
 343 {
 344         struct server_command_task *sct = context;
 345         para_fd_set(sct->listen_fd, &s->rfds, &s->max_fileno);
 346 }
 347
 348 static int command_post_select(struct sched *s, void *context)
 349 {
 350         struct server_command_task *sct = context;
 351
 352         int new_fd, ret, i;
 353         char *peer_name;
 354         pid_t child_pid;
 355         uint32_t *chunk_table;
 356
 357         ret = para_accept(sct->listen_fd, &s->rfds, NULL, 0, &new_fd);
 358         if (ret <= 0)
 359                 goto out;
 360         mmd->num_connects++;
 361         mmd->active_connections++;
 362         /*
 363          * The chunk table is a pointer located in the mmd struct that points
 364          * to dynamically allocated memory, i.e. it must be freed by the parent
 365          * and the child. However, as the mmd struct is in a shared memory
 366          * area, there's no guarantee that after the fork this pointer is still
 367          * valid in child context. As it is not used in the child anyway, we
 368          * save it to a local variable before the fork and free the memory via
 369          * that copy in the child directly after the fork.
 370          */
 371         chunk_table = mmd->afd.afhi.chunk_table;
 372         child_pid = fork();
 373         if (child_pid < 0) {
 374                 ret = -ERRNO_TO_PARA_ERROR(errno);
 375                 goto out;
 376         }
 377         if (child_pid) {
 378                 /* avoid problems with non-fork-safe PRNGs */
 379                 unsigned char buf[16];
 380                 get_random_bytes_or_die(buf, sizeof(buf));
 381                 close(new_fd);
 382                 /* parent keeps accepting connections */
 383                 return 0;
 384         }
 385         peer_name = remote_name(new_fd);
 386         PARA_INFO_LOG("accepted connection from %s\n", peer_name);
 387         /* mmd might already have changed at this point */
 388         free(chunk_table);
 389         alarm(ALARM_TIMEOUT);
 390         close_listed_fds();
 391         signal_shutdown(signal_task);
 392         /*
 393          * put info on who we are serving into argv[0] to make
 394          * client ip visible in top/ps
 395          */
 396         for (i = sct->argc - 1; i >= 0; i--)
 397                 memset(sct->argv[i], 0, strlen(sct->argv[i]));
 398         i = sct->argc - 1 - lls_num_inputs(cmdline_lpr);
 399         sprintf(sct->argv[i], "para_server (serving %s)", peer_name);
 400         handle_connect(new_fd, peer_name);
 401         /* never reached*/
 402 out:
 403         if (ret < 0)
 404                 PARA_CRIT_LOG("%s\n", para_strerror(-ret));
 405         return 0;
 406 }
 407
 408 static void init_server_command_task(int argc, char **argv)
 409 {
 410         int ret;
 411         static struct server_command_task server_command_task_struct,
 412                 *sct = &server_command_task_struct;
 413
 414         PARA_NOTICE_LOG("initializing tcp command socket\n");
 415         sct->argc = argc;
 416         sct->argv = argv;
 417         ret = para_listen_simple(IPPROTO_TCP, OPT_UINT32_VAL(PORT));
 418         if (ret < 0)
 419                 goto err;
 420         sct->listen_fd = ret;
 421         ret = mark_fd_nonblocking(sct->listen_fd);
 422         if (ret < 0)
 423                 goto err;
 424         add_close_on_fork_list(sct->listen_fd); /* child doesn't need the listener */
 425         sct->task = task_register(&(struct task_info) {
 426                 .name = "server command",
 427                 .pre_select = command_pre_select,
 428                 .post_select = command_post_select,
 429                 .context = sct,
 430         }, &sched);
 431         return;
 432 err:
 433         PARA_EMERG_LOG("%s\n", para_strerror(-ret));
 434         exit(EXIT_FAILURE);
 435 }
 436
 437 static int init_afs(int argc, char **argv)
 438 {
 439         int ret, afs_server_socket[2];
 440         pid_t afs_pid;
 441         char c;
 442
 443         ret = socketpair(PF_UNIX, SOCK_STREAM, 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                 int i;
 453
 454                 for (i = argc - 1; i >= 0; i--)
 455                         memset(argv[i], 0, strlen(argv[i]));
 456                 i = argc - lls_num_inputs(cmdline_lpr) - 1;
 457                 sprintf(argv[i], "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         if (read(afs_server_socket[0], &c, 1) <= 0) {
 464                 PARA_EMERG_LOG("early afs exit\n");
 465                 exit(EXIT_FAILURE);
 466         }
 467         ret = mark_fd_nonblocking(afs_server_socket[0]);
 468         if (ret < 0)
 469                 exit(EXIT_FAILURE);
 470         add_close_on_fork_list(afs_server_socket[0]);
 471         PARA_INFO_LOG("afs_socket: %d, afs_socket_cookie: %u\n",
 472                 afs_server_socket[0], (unsigned) afs_socket_cookie);
 473         return afs_server_socket[0];
 474 }
 475
 476 static void handle_help_flags(void)
 477 {
 478         char *help;
 479         bool d = OPT_GIVEN(DETAILED_HELP);
 480
 481         if (d)
 482                 help = lls_long_help(CMD_PTR);
 483         else if (OPT_GIVEN(HELP))
 484                 help = lls_short_help(CMD_PTR);
 485         else
 486                 return;
 487         printf("%s\n", help);
 488         free(help);
 489         exit(EXIT_SUCCESS);
 490 }
 491
 492 static void server_init(int argc, char **argv)
 493 {
 494         int ret, afs_socket, daemon_pipe = -1;
 495         char *errctx;
 496
 497         valid_fd_012();
 498         /* parse command line options */
 499         ret = lls(lls_parse(argc, argv, CMD_PTR, &cmdline_lpr, &errctx));
 500         if (ret < 0)
 501                 goto fail;
 502         server_lpr = cmdline_lpr;
 503         daemon_set_loglevel(ENUM_STRING_VAL(LOGLEVEL));
 504         daemon_drop_privileges_or_die(OPT_STRING_VAL(USER),
 505                 OPT_STRING_VAL(GROUP));
 506         version_handle_flag("server", OPT_GIVEN(VERSION));
 507         handle_help_flags();
 508         parse_config_or_die(false);
 509         /* become daemon */
 510         if (OPT_GIVEN(DAEMON))
 511                 daemon_pipe = daemonize(true /* parent waits for SIGTERM */);
 512         init_random_seed_or_die();
 513         daemon_log_welcome("server");
 514         init_ipc_or_die(); /* init mmd struct and mmd->lock */
 515         daemon_set_start_time();
 516         PARA_NOTICE_LOG("initializing audio format handlers\n");
 517         afh_init();
 518
 519         /*
 520          * Although afs uses its own signal handling we must ignore SIGUSR1
 521          * _before_ the afs child process gets born by init_afs() below.  It's
 522          * racy to do this in the child because the parent might send SIGUSR1
 523          * before the child gets a chance to ignore this signal.
 524          *
 525          * We also have to block SIGCHLD before the afs process is created
 526          * because otherwise para_server does not notice if afs dies before the
 527          * SIGCHLD handler has been installed for the parent process by
 528          * init_signal_task() below.
 529          */
 530         para_sigaction(SIGUSR1, SIG_IGN);
 531         para_block_signal(SIGCHLD);
 532         PARA_NOTICE_LOG("initializing the audio file selector\n");
 533         afs_socket = init_afs(argc, argv);
 534         init_signal_task();
 535         para_unblock_signal(SIGCHLD);
 536         PARA_NOTICE_LOG("initializing virtual streaming system\n");
 537         vss_init(afs_socket, &sched);
 538         init_server_command_task(argc, argv);
 539         if (daemon_pipe >= 0) {
 540                 if (write(daemon_pipe, "\0", 1) < 0) {
 541                         PARA_EMERG_LOG("daemon_pipe: %s", strerror(errno));
 542                         exit(EXIT_FAILURE);
 543                 }
 544                 close(daemon_pipe);
 545         }
 546         PARA_NOTICE_LOG("server init complete\n");
 547         return;
 548 fail:
 549         assert(ret < 0);
 550         if (errctx)
 551                 PARA_ERROR_LOG("%s\n", errctx);
 552         PARA_EMERG_LOG("%s\n", para_strerror(-ret));
 553         exit(EXIT_FAILURE);
 554 }
 555
 556 static void status_refresh(void)
 557 {
 558         static int prev_uptime = -1, prev_events = -1;
 559         int uptime = daemon_get_uptime(now);
 560
 561         if (prev_events != mmd->events)
 562                 goto out;
 563         if (mmd->new_vss_status_flags != mmd->vss_status_flags)
 564                 goto out_inc_events;
 565         if (uptime / 60 != prev_uptime / 60)
 566                 goto out_inc_events;
 567         return;
 568 out_inc_events:
 569         mmd->events++;
 570 out:
 571         prev_uptime = uptime;
 572         prev_events = mmd->events;
 573         mmd->vss_status_flags = mmd->new_vss_status_flags;
 574         PARA_DEBUG_LOG("%u events, forcing status update\n", mmd->events);
 575         killpg(0, SIGUSR1);
 576 }
 577
 578 static int server_select(int max_fileno, fd_set *readfds, fd_set *writefds,
 579                 struct timeval *timeout_tv)
 580 {
 581         int ret;
 582
 583         status_refresh();
 584         mutex_unlock(mmd_mutex);
 585         ret = para_select(max_fileno + 1, readfds, writefds, timeout_tv);
 586         mutex_lock(mmd_mutex);
 587         return ret;
 588 }
 589
 590 /**
 591  * The main function of para_server.
 592  *
 593  * \param argc Usual argument count.
 594  * \param argv Usual argument vector.
 595  *
 596  * \return EXIT_SUCCESS or EXIT_FAILURE.
 597  */
 598 int main(int argc, char *argv[])
 599 {
 600         int ret;
 601
 602         sched.default_timeout.tv_sec = 1;
 603         sched.select_function = server_select;
 604
 605         server_init(argc, argv);
 606         mutex_lock(mmd_mutex);
 607         ret = schedule(&sched);
 608         sched_shutdown(&sched);
 609         lls_free_parse_result(server_lpr, CMD_PTR);
 610         if (server_lpr != cmdline_lpr)
 611                 lls_free_parse_result(cmdline_lpr, CMD_PTR);
 612         if (ret < 0)
 613                 PARA_EMERG_LOG("%s\n", para_strerror(-ret));
 614         exit(ret < 0? EXIT_FAILURE : EXIT_SUCCESS);
 615 }