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
  44 #include "para.h"
  45 #include "error.h"
  46 #include "crypt.h"
  47 #include "server.cmdline.h"
  48 #include "afh.h"
  49 #include "string.h"
  50 #include "afs.h"
  51 #include "server.h"
  52 #include "list.h"
  53 #include "send.h"
  54 #include "sched.h"
  55 #include "vss.h"
  56 #include "config.h"
  57 #include "close_on_fork.h"
  58 #include "net.h"
  59 #include "daemon.h"
  60 #include "ipc.h"
  61 #include "fd.h"
  62 #include "signal.h"
  63 #include "user_list.h"
  64 #include "color.h"
  65 #include "ggo.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 configuration of para_server
  84  *
  85  * It also contains the options for the audio file selector, audio format
  86  * handler and all supported senders.
  87  */
  88 struct server_args_info conf;
  89
  90 /** A random value used in child context for authentication. */
  91 uint32_t afs_socket_cookie;
  92
  93 /** The mutex protecting the shared memory area containing the mmd struct. */
  94 int mmd_mutex;
  95
  96 /** The file containing user information (public key, permissions). */
  97 static char *user_list_file = NULL;
  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 override Passed to gengetopt to activate the override feature.
 166  *
 167  * This function also re-opens the logfile and sets the global \a
 168  * user_list_file variable.
 169  */
 170 void parse_config_or_die(int override)
 171 {
 172         char *home = para_homedir();
 173         int ret;
 174         char *cf;
 175
 176         daemon_close_log();
 177         if (conf.config_file_given)
 178                 cf = para_strdup(conf.config_file_arg);
 179         else
 180                 cf = make_message("%s/.paraslash/server.conf", home);
 181         free(user_list_file);
 182         if (!conf.user_list_given)
 183                 user_list_file = make_message("%s/.paraslash/server.users", home);
 184         else
 185                 user_list_file = para_strdup(conf.user_list_arg);
 186         ret = file_exists(cf);
 187         if (conf.config_file_given && !ret)  {
 188                 ret = -1;
 189                 PARA_EMERG_LOG("can not read config file %s\n", cf);
 190                 goto out;
 191         }
 192         if (ret) {
 193                 int tmp = conf.daemon_given;
 194                 struct server_cmdline_parser_params params = {
 195                         .override = override,
 196                         .initialize = 0,
 197                         .check_required = 1,
 198                         .check_ambiguity = 0,
 199                         .print_errors = !conf.daemon_given
 200                 };
 201                 server_cmdline_parser_config_file(cf, &conf, &params);
 202                 daemon_set_loglevel(conf.loglevel_arg);
 203                 conf.daemon_given = tmp;
 204         }
 205         if (conf.logfile_given) {
 206                 daemon_set_logfile(conf.logfile_arg);
 207                 daemon_open_log_or_die();
 208         }
 209
 210         if (daemon_init_colors_or_die(conf.color_arg, color_arg_auto, color_arg_no,
 211                         conf.logfile_given)) {
 212                 int i;
 213                 for (i = 0; i < conf.log_color_given; i++)
 214                         daemon_set_log_color_or_die(conf.log_color_arg[i]);
 215         }
 216         daemon_set_flag(DF_LOG_PID);
 217         daemon_set_flag(DF_LOG_LL);
 218         daemon_set_flag(DF_LOG_TIME);
 219         if (conf.log_timing_given)
 220                 daemon_set_flag(DF_LOG_TIMING);
 221         ret = 1;
 222 out:
 223         free(cf);
 224         free(home);
 225         if (ret > 0)
 226                 return;
 227         free(user_list_file);
 228         user_list_file = NULL;
 229         exit(EXIT_FAILURE);
 230 }
 231
 232 /*
 233  * called when server gets SIGHUP or when client invokes hup command.
 234  */
 235 static void handle_sighup(void)
 236 {
 237         PARA_NOTICE_LOG("SIGHUP\n");
 238         parse_config_or_die(1); /* reopens log */
 239         init_user_list(user_list_file); /* reload user list */
 240         if (mmd->afs_pid)
 241                 kill(mmd->afs_pid, SIGHUP);
 242 }
 243
 244 static int signal_post_select(struct sched *s, __a_unused void *context)
 245 {
 246         int signum = para_next_signal(&s->rfds);
 247
 248         switch (signum) {
 249         case 0:
 250                 return 0;
 251         case SIGHUP:
 252                 handle_sighup();
 253                 break;
 254         case SIGCHLD:
 255                 for (;;) {
 256                         pid_t pid;
 257                         int ret = para_reap_child(&pid);
 258                         if (ret <= 0)
 259                                 break;
 260                         if (pid != mmd->afs_pid)
 261                                 continue;
 262                         PARA_EMERG_LOG("fatal: afs died\n");
 263                         kill(0, SIGTERM);
 264                         goto cleanup;
 265                 }
 266                 break;
 267         /* die on sigint/sigterm. Kill all children too. */
 268         case SIGINT:
 269         case SIGTERM:
 270                 PARA_EMERG_LOG("terminating on signal %d\n", signum);
 271                 kill(0, SIGTERM);
 272                 /*
 273                  * We must wait for afs because afs catches SIGINT/SIGTERM.
 274                  * Before reacting to the signal, afs might want to use the
 275                  * shared memory area and the mmd mutex.  If we destroy this
 276                  * mutex too early and afs tries to lock the shared memory
 277                  * area, the call to mutex_lock() will fail and terminate the
 278                  * afs process. This leads to dirty osl tables.
 279                  *
 280                  * There's no such problem with the other children of the
 281                  * server process (the command handlers) as these reset their
 282                  * SIGINT/SIGTERM handlers to the default action, i.e.  these
 283                  * processes get killed immediately by the above kill().
 284                  */
 285                 PARA_INFO_LOG("waiting for afs (pid %d) to die\n",
 286                         (int)mmd->afs_pid);
 287                 waitpid(mmd->afs_pid, NULL, 0);
 288 cleanup:
 289                 free(mmd->afd.afhi.chunk_table);
 290                 close_listed_fds();
 291                 mutex_destroy(mmd_mutex);
 292                 shm_detach(mmd);
 293                 exit(EXIT_FAILURE);
 294         }
 295         return 0;
 296 }
 297
 298 static void init_signal_task(void)
 299 {
 300         signal_task = signal_init_or_die();
 301         para_install_sighandler(SIGINT);
 302         para_install_sighandler(SIGTERM);
 303         para_install_sighandler(SIGHUP);
 304         para_install_sighandler(SIGCHLD);
 305         para_sigaction(SIGPIPE, SIG_IGN);
 306         add_close_on_fork_list(signal_task->fd);
 307         signal_task->task = task_register(&(struct task_info) {
 308                 .name = "signal",
 309                 .pre_select = signal_pre_select,
 310                 .post_select = signal_post_select,
 311                 .context = signal_task,
 312
 313         }, &sched);
 314 }
 315
 316 static void command_pre_select(struct sched *s, void *context)
 317 {
 318         struct server_command_task *sct = context;
 319         para_fd_set(sct->listen_fd, &s->rfds, &s->max_fileno);
 320 }
 321
 322 static int command_post_select(struct sched *s, void *context)
 323 {
 324         struct server_command_task *sct = context;
 325
 326         int new_fd, ret, i;
 327         char *peer_name;
 328         pid_t child_pid;
 329         uint32_t *chunk_table;
 330
 331         ret = para_accept(sct->listen_fd, &s->rfds, NULL, 0, &new_fd);
 332         if (ret <= 0)
 333                 goto out;
 334         peer_name = remote_name(new_fd);
 335         PARA_INFO_LOG("got connection from %s, forking\n", peer_name);
 336         mmd->num_connects++;
 337         mmd->active_connections++;
 338         /*
 339          * The chunk table is a pointer located in the mmd struct that points
 340          * to dynamically allocated memory, i.e. it must be freed by the parent
 341          * and the child. However, as the mmd struct is in a shared memory
 342          * area, there's no guarantee that after the fork this pointer is still
 343          * valid in child context. As it is not used in the child anyway, we
 344          * save it to a local variable before the fork and free the memory via
 345          * that copy in the child directly after the fork.
 346          */
 347         chunk_table = mmd->afd.afhi.chunk_table;
 348         child_pid = fork();
 349         if (child_pid < 0) {
 350                 ret = -ERRNO_TO_PARA_ERROR(errno);
 351                 goto out;
 352         }
 353         if (child_pid) {
 354                 /* avoid problems with non-fork-safe PRNGs */
 355                 unsigned char buf[16];
 356                 get_random_bytes_or_die(buf, sizeof(buf));
 357                 close(new_fd);
 358                 /* parent keeps accepting connections */
 359                 return 0;
 360         }
 361         /* mmd might already have changed at this point */
 362         free(chunk_table);
 363         alarm(ALARM_TIMEOUT);
 364         close_listed_fds();
 365         signal_shutdown(signal_task);
 366         /*
 367          * put info on who we are serving into argv[0] to make
 368          * client ip visible in top/ps
 369          */
 370         for (i = sct->argc - 1; i >= 0; i--)
 371                 memset(sct->argv[i], 0, strlen(sct->argv[i]));
 372         sprintf(sct->argv[0], "para_server (serving %s)", peer_name);
 373         handle_connect(new_fd, peer_name);
 374         /* never reached*/
 375 out:
 376         if (ret < 0)
 377                 PARA_CRIT_LOG("%s\n", para_strerror(-ret));
 378         return 0;
 379 }
 380
 381 static void init_server_command_task(int argc, char **argv)
 382 {
 383         int ret;
 384         static struct server_command_task server_command_task_struct,
 385                 *sct = &server_command_task_struct;
 386
 387         PARA_NOTICE_LOG("initializing tcp command socket\n");
 388         sct->argc = argc;
 389         sct->argv = argv;
 390         ret = para_listen_simple(IPPROTO_TCP, conf.port_arg);
 391         if (ret < 0)
 392                 goto err;
 393         sct->listen_fd = ret;
 394         ret = mark_fd_nonblocking(sct->listen_fd);
 395         if (ret < 0)
 396                 goto err;
 397         add_close_on_fork_list(sct->listen_fd); /* child doesn't need the listener */
 398         sct->task = task_register(&(struct task_info) {
 399                 .name = "server command",
 400                 .pre_select = command_pre_select,
 401                 .post_select = command_post_select,
 402                 .context = sct,
 403         }, &sched);
 404         return;
 405 err:
 406         PARA_EMERG_LOG("%s\n", para_strerror(-ret));
 407         exit(EXIT_FAILURE);
 408 }
 409
 410 static int init_afs(int argc, char **argv)
 411 {
 412         int ret, afs_server_socket[2];
 413         pid_t afs_pid;
 414         char c;
 415
 416         ret = socketpair(PF_UNIX, SOCK_STREAM, 0, afs_server_socket);
 417         if (ret < 0)
 418                 exit(EXIT_FAILURE);
 419         get_random_bytes_or_die((unsigned char *)&afs_socket_cookie,
 420                 sizeof(afs_socket_cookie));
 421         afs_pid = fork();
 422         if (afs_pid < 0)
 423                 exit(EXIT_FAILURE);
 424         if (afs_pid == 0) { /* child (afs) */
 425                 int i;
 426
 427                 for (i = argc - 1; i >= 0; i--)
 428                         memset(argv[i], 0, strlen(argv[i]));
 429                 sprintf(argv[0], "para_server (afs)");
 430                 close(afs_server_socket[0]);
 431                 afs_init(afs_socket_cookie, afs_server_socket[1]);
 432         }
 433         mmd->afs_pid = afs_pid;
 434         close(afs_server_socket[1]);
 435         if (read(afs_server_socket[0], &c, 1) <= 0) {
 436                 PARA_EMERG_LOG("early afs exit\n");
 437                 exit(EXIT_FAILURE);
 438         }
 439         ret = mark_fd_nonblocking(afs_server_socket[0]);
 440         if (ret < 0)
 441                 exit(EXIT_FAILURE);
 442         add_close_on_fork_list(afs_server_socket[0]);
 443         PARA_INFO_LOG("afs_socket: %d, afs_socket_cookie: %u\n",
 444                 afs_server_socket[0], (unsigned) afs_socket_cookie);
 445         return afs_server_socket[0];
 446 }
 447
 448 __noreturn static void print_help_and_die(void)
 449 {
 450         struct ggo_help h = DEFINE_GGO_HELP(server);
 451         bool d = conf.detailed_help_given;
 452
 453         ggo_print_help(&h, d? GPH_STANDARD_FLAGS_DETAILED : GPH_STANDARD_FLAGS);
 454         exit(0);
 455 }
 456
 457 static void server_init(int argc, char **argv)
 458 {
 459         struct server_cmdline_parser_params params = {
 460                 .override = 0,
 461                 .initialize = 1,
 462                 .check_required = 0,
 463                 .check_ambiguity = 0,
 464                 .print_errors = 1
 465         };
 466         int afs_socket, daemon_pipe = -1;
 467
 468         valid_fd_012();
 469         init_random_seed_or_die();
 470         /* parse command line options */
 471         server_cmdline_parser_ext(argc, argv, &conf, &params);
 472         daemon_set_loglevel(conf.loglevel_arg);
 473         version_handle_flag("server", conf.version_given);
 474         if (conf.help_given || conf.detailed_help_given)
 475                 print_help_and_die();
 476         daemon_set_priority(conf.priority_arg);
 477         daemon_drop_privileges_or_die(conf.user_arg, conf.group_arg);
 478         /* parse config file, open log and set defaults */
 479         parse_config_or_die(0);
 480         daemon_log_welcome("server");
 481         init_ipc_or_die(); /* init mmd struct and mmd->lock */
 482         daemon_set_start_time();
 483         init_user_list(user_list_file);
 484         /* become daemon */
 485         if (conf.daemon_given)
 486                 daemon_pipe = daemonize(true /* parent waits for us */);
 487         PARA_NOTICE_LOG("initializing audio format handlers\n");
 488         afh_init();
 489
 490         /*
 491          * Although afs uses its own signal handling we must ignore SIGUSR1
 492          * _before_ the afs child process gets born by init_afs() below.  It's
 493          * racy to do this in the child because the parent might send SIGUSR1
 494          * before the child gets a chance to ignore this signal -- only the
 495          * good die young.
 496          */
 497         para_sigaction(SIGUSR1, SIG_IGN);
 498         /*
 499          * We have to block SIGCHLD before the afs process is being forked off.
 500          * Otherwise, para_server does not notice if afs dies before the
 501          * SIGCHLD handler has been installed for the parent process by
 502          * init_signal_task() below.
 503          */
 504         para_block_signal(SIGCHLD);
 505         PARA_NOTICE_LOG("initializing the audio file selector\n");
 506         afs_socket = init_afs(argc, argv);
 507         init_signal_task();
 508         para_unblock_signal(SIGCHLD);
 509         PARA_NOTICE_LOG("initializing virtual streaming system\n");
 510         init_vss_task(afs_socket, &sched);
 511         init_server_command_task(argc, argv);
 512         if (daemon_pipe >= 0) {
 513                 if (write(daemon_pipe, "\0", 1) < 0) {
 514                         PARA_EMERG_LOG("daemon_pipe: %s", strerror(errno));
 515                         exit(EXIT_FAILURE);
 516                 }
 517                 close(daemon_pipe);
 518         }
 519         PARA_NOTICE_LOG("server init complete\n");
 520 }
 521
 522 static void status_refresh(void)
 523 {
 524         static int prev_uptime = -1, prev_events = -1;
 525         int uptime = daemon_get_uptime(now);
 526
 527         if (prev_events != mmd->events)
 528                 goto out;
 529         if (mmd->new_vss_status_flags != mmd->vss_status_flags)
 530                 goto out_inc_events;
 531         if (uptime / 60 != prev_uptime / 60)
 532                 goto out_inc_events;
 533         return;
 534 out_inc_events:
 535         mmd->events++;
 536 out:
 537         prev_uptime = uptime;
 538         prev_events = mmd->events;
 539         mmd->vss_status_flags = mmd->new_vss_status_flags;
 540         PARA_DEBUG_LOG("%u events, forcing status update\n", mmd->events);
 541         killpg(0, SIGUSR1);
 542 }
 543
 544 static int server_select(int max_fileno, fd_set *readfds, fd_set *writefds,
 545                 struct timeval *timeout_tv)
 546 {
 547         int ret;
 548
 549         status_refresh();
 550         mutex_unlock(mmd_mutex);
 551         ret = para_select(max_fileno + 1, readfds, writefds, timeout_tv);
 552         mutex_lock(mmd_mutex);
 553         return ret;
 554 }
 555
 556 /**
 557  * The main function of para_server.
 558  *
 559  * \param argc Usual argument count.
 560  * \param argv Usual argument vector.
 561  *
 562  * \return EXIT_SUCCESS or EXIT_FAILURE.
 563  */
 564 int main(int argc, char *argv[])
 565 {
 566         int ret;
 567
 568         sched.default_timeout.tv_sec = 1;
 569         sched.select_function = server_select;
 570
 571         server_init(argc, argv);
 572         mutex_lock(mmd_mutex);
 573         ret = schedule(&sched);
 574         sched_shutdown(&sched);
 575         if (ret < 0) {
 576                 PARA_EMERG_LOG("%s\n", para_strerror(-ret));
 577                 exit(EXIT_FAILURE);
 578         }
 579         exit(EXIT_SUCCESS);
 580 }