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 "para.h"
  46 #include "error.h"
  47 #include "crypt.h"
  48 #include "server.cmdline.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 "ggo.h"
  67 #include "version.h"
  68
  69 /** Array of error strings. */
  70 DEFINE_PARA_ERRLIST;
  71
  72 __printf_2_3 void (*para_log)(int, const char*, ...) = daemon_log;
  73
  74 /** Shut down non-authorized connections after that many seconds. */
  75 #define ALARM_TIMEOUT 10
  76
  77 /**
  78  * Pointer to shared memory area for communication between para_server
  79  * and its children. Exported to vss.c, command.c and to afs.
  80  */
  81 struct misc_meta_data *mmd;
  82
  83 /**
  84  * The configuration of para_server
  85  *
  86  * It also contains the options for the audio file selector, audio format
  87  * handler and all supported senders.
  88  */
  89 struct server_args_info conf;
  90
  91 /** A random value used in child context for authentication. */
  92 uint32_t afs_socket_cookie;
  93
  94 /** The mutex protecting the shared memory area containing the mmd struct. */
  95 int mmd_mutex;
  96
  97 /** The file containing user information (public key, permissions). */
  98 static char *user_list_file = NULL;
  99
 100 static struct sched sched;
 101 static struct signal_task *signal_task;
 102
 103 /** The task responsible for server command handling. */
 104 struct server_command_task {
 105         /** TCP port on which para_server listens for connections. */
 106         int listen_fd;
 107         /** Copied from para_server's main function. */
 108         int argc;
 109         /** Argument vector passed to para_server's main function. */
 110         char **argv;
 111         /** The command task structure for scheduling. */
 112         struct task *task;
 113 };
 114
 115 /**
 116  * Return the list of tasks for the server process.
 117  *
 118  * This is called from \a com_tasks(). The helper is necessary since command
 119  * handlers can not access the scheduler structure directly.
 120  *
 121  * \return A dynamically allocated string that must be freed by the caller.
 122  */
 123 char *server_get_tasks(void)
 124 {
 125         return get_task_list(&sched);
 126 }
 127
 128 /*
 129  * setup shared memory area and get mutex for locking
 130  */
 131 static void init_ipc_or_die(void)
 132 {
 133         void *shm;
 134         int shmid, ret = shm_new(sizeof(struct misc_meta_data));
 135
 136         if (ret < 0)
 137                 goto err_out;
 138         shmid = ret;
 139         ret = shm_attach(shmid, ATTACH_RW, &shm);
 140         shm_destroy(shmid);
 141         if (ret < 0)
 142                 goto err_out;
 143         mmd = shm;
 144
 145         ret = mutex_new();
 146         if (ret < 0)
 147                 goto err_out;
 148         mmd_mutex = ret;
 149
 150         mmd->num_played = 0;
 151         mmd->num_commands = 0;
 152         mmd->events = 0;
 153         mmd->num_connects = 0;
 154         mmd->active_connections = 0;
 155         mmd->vss_status_flags = VSS_NEXT;
 156         mmd->new_vss_status_flags = VSS_NEXT;
 157         return;
 158 err_out:
 159         PARA_EMERG_LOG("%s\n", para_strerror(-ret));
 160         exit(EXIT_FAILURE);
 161 }
 162
 163 /**
 164  * (Re-)read the server configuration files.
 165  *
 166  * \param override Passed to gengetopt to activate the override feature.
 167  *
 168  * This function also re-opens the logfile and sets the global \a
 169  * user_list_file variable.
 170  */
 171 void parse_config_or_die(int override)
 172 {
 173         char *home = para_homedir();
 174         int ret;
 175         char *cf;
 176
 177         daemon_close_log();
 178         if (conf.config_file_given)
 179                 cf = para_strdup(conf.config_file_arg);
 180         else
 181                 cf = make_message("%s/.paraslash/server.conf", home);
 182         free(user_list_file);
 183         if (!conf.user_list_given)
 184                 user_list_file = make_message("%s/.paraslash/server.users", home);
 185         else
 186                 user_list_file = para_strdup(conf.user_list_arg);
 187         ret = file_exists(cf);
 188         if (conf.config_file_given && !ret)  {
 189                 ret = -1;
 190                 PARA_EMERG_LOG("can not read config file %s\n", cf);
 191                 goto out;
 192         }
 193         if (ret) {
 194                 int tmp = conf.daemon_given;
 195                 struct server_cmdline_parser_params params = {
 196                         .override = override,
 197                         .initialize = 0,
 198                         .check_required = 1,
 199                         .check_ambiguity = 0,
 200                         .print_errors = !conf.daemon_given
 201                 };
 202                 server_cmdline_parser_config_file(cf, &conf, &params);
 203                 daemon_set_loglevel(conf.loglevel_arg);
 204                 conf.daemon_given = tmp;
 205         }
 206         if (conf.logfile_given) {
 207                 daemon_set_logfile(conf.logfile_arg);
 208                 daemon_open_log_or_die();
 209         }
 210
 211         if (daemon_init_colors_or_die(conf.color_arg, color_arg_auto, color_arg_no,
 212                         conf.logfile_given)) {
 213                 int i;
 214                 for (i = 0; i < conf.log_color_given; i++)
 215                         daemon_set_log_color_or_die(conf.log_color_arg[i]);
 216         }
 217         daemon_set_flag(DF_LOG_PID);
 218         daemon_set_flag(DF_LOG_LL);
 219         daemon_set_flag(DF_LOG_TIME);
 220         if (conf.log_timing_given)
 221                 daemon_set_flag(DF_LOG_TIMING);
 222         ret = 1;
 223 out:
 224         free(cf);
 225         free(home);
 226         if (ret > 0)
 227                 return;
 228         free(user_list_file);
 229         user_list_file = NULL;
 230         exit(EXIT_FAILURE);
 231 }
 232
 233 /*
 234  * called when server gets SIGHUP or when client invokes hup command.
 235  */
 236 static void handle_sighup(void)
 237 {
 238         PARA_NOTICE_LOG("SIGHUP\n");
 239         parse_config_or_die(1); /* reopens log */
 240         init_user_list(user_list_file); /* reload user list */
 241         if (mmd->afs_pid)
 242                 kill(mmd->afs_pid, SIGHUP);
 243 }
 244
 245 static int signal_post_select(struct sched *s, __a_unused void *context)
 246 {
 247         int signum = para_next_signal(&s->rfds);
 248
 249         switch (signum) {
 250         case 0:
 251                 return 0;
 252         case SIGHUP:
 253                 handle_sighup();
 254                 break;
 255         case SIGCHLD:
 256                 for (;;) {
 257                         pid_t pid;
 258                         int ret = para_reap_child(&pid);
 259                         if (ret <= 0)
 260                                 break;
 261                         if (pid != mmd->afs_pid)
 262                                 continue;
 263                         PARA_EMERG_LOG("fatal: afs died\n");
 264                         kill(0, SIGTERM);
 265                         goto cleanup;
 266                 }
 267                 break;
 268         /* die on sigint/sigterm. Kill all children too. */
 269         case SIGINT:
 270         case SIGTERM:
 271                 PARA_EMERG_LOG("terminating on signal %d\n", signum);
 272                 kill(0, SIGTERM);
 273                 /*
 274                  * We must wait for afs because afs catches SIGINT/SIGTERM.
 275                  * Before reacting to the signal, afs might want to use the
 276                  * shared memory area and the mmd mutex.  If we destroy this
 277                  * mutex too early and afs tries to lock the shared memory
 278                  * area, the call to mutex_lock() will fail and terminate the
 279                  * afs process. This leads to dirty osl tables.
 280                  *
 281                  * There's no such problem with the other children of the
 282                  * server process (the command handlers) as these reset their
 283                  * SIGINT/SIGTERM handlers to the default action, i.e.  these
 284                  * processes get killed immediately by the above kill().
 285                  */
 286                 PARA_INFO_LOG("waiting for afs (pid %d) to die\n",
 287                         (int)mmd->afs_pid);
 288                 waitpid(mmd->afs_pid, NULL, 0);
 289 cleanup:
 290                 free(mmd->afd.afhi.chunk_table);
 291                 close_listed_fds();
 292                 mutex_destroy(mmd_mutex);
 293                 shm_detach(mmd);
 294                 exit(EXIT_FAILURE);
 295         }
 296         return 0;
 297 }
 298
 299 static void init_signal_task(void)
 300 {
 301         signal_task = signal_init_or_die();
 302         para_install_sighandler(SIGINT);
 303         para_install_sighandler(SIGTERM);
 304         para_install_sighandler(SIGHUP);
 305         para_install_sighandler(SIGCHLD);
 306         para_sigaction(SIGPIPE, SIG_IGN);
 307         add_close_on_fork_list(signal_task->fd);
 308         signal_task->task = task_register(&(struct task_info) {
 309                 .name = "signal",
 310                 .pre_select = signal_pre_select,
 311                 .post_select = signal_post_select,
 312                 .context = signal_task,
 313
 314         }, &sched);
 315 }
 316
 317 static void command_pre_select(struct sched *s, void *context)
 318 {
 319         struct server_command_task *sct = context;
 320         para_fd_set(sct->listen_fd, &s->rfds, &s->max_fileno);
 321 }
 322
 323 static int command_post_select(struct sched *s, void *context)
 324 {
 325         struct server_command_task *sct = context;
 326
 327         int new_fd, ret, i;
 328         char *peer_name;
 329         pid_t child_pid;
 330         uint32_t *chunk_table;
 331
 332         ret = para_accept(sct->listen_fd, &s->rfds, NULL, 0, &new_fd);
 333         if (ret <= 0)
 334                 goto out;
 335         peer_name = remote_name(new_fd);
 336         PARA_INFO_LOG("got connection from %s, forking\n", peer_name);
 337         mmd->num_connects++;
 338         mmd->active_connections++;
 339         /*
 340          * The chunk table is a pointer located in the mmd struct that points
 341          * to dynamically allocated memory, i.e. it must be freed by the parent
 342          * and the child. However, as the mmd struct is in a shared memory
 343          * area, there's no guarantee that after the fork this pointer is still
 344          * valid in child context. As it is not used in the child anyway, we
 345          * save it to a local variable before the fork and free the memory via
 346          * that copy in the child directly after the fork.
 347          */
 348         chunk_table = mmd->afd.afhi.chunk_table;
 349         child_pid = fork();
 350         if (child_pid < 0) {
 351                 ret = -ERRNO_TO_PARA_ERROR(errno);
 352                 goto out;
 353         }
 354         if (child_pid) {
 355                 /* avoid problems with non-fork-safe PRNGs */
 356                 unsigned char buf[16];
 357                 get_random_bytes_or_die(buf, sizeof(buf));
 358                 close(new_fd);
 359                 /* parent keeps accepting connections */
 360                 return 0;
 361         }
 362         /* mmd might already have changed at this point */
 363         free(chunk_table);
 364         alarm(ALARM_TIMEOUT);
 365         close_listed_fds();
 366         signal_shutdown(signal_task);
 367         /*
 368          * put info on who we are serving into argv[0] to make
 369          * client ip visible in top/ps
 370          */
 371         for (i = sct->argc - 1; i >= 0; i--)
 372                 memset(sct->argv[i], 0, strlen(sct->argv[i]));
 373         sprintf(sct->argv[0], "para_server (serving %s)", peer_name);
 374         handle_connect(new_fd, peer_name);
 375         /* never reached*/
 376 out:
 377         if (ret < 0)
 378                 PARA_CRIT_LOG("%s\n", para_strerror(-ret));
 379         return 0;
 380 }
 381
 382 static void init_server_command_task(int argc, char **argv)
 383 {
 384         int ret;
 385         static struct server_command_task server_command_task_struct,
 386                 *sct = &server_command_task_struct;
 387
 388         PARA_NOTICE_LOG("initializing tcp command socket\n");
 389         sct->argc = argc;
 390         sct->argv = argv;
 391         ret = para_listen_simple(IPPROTO_TCP, conf.port_arg);
 392         if (ret < 0)
 393                 goto err;
 394         sct->listen_fd = ret;
 395         ret = mark_fd_nonblocking(sct->listen_fd);
 396         if (ret < 0)
 397                 goto err;
 398         add_close_on_fork_list(sct->listen_fd); /* child doesn't need the listener */
 399         sct->task = task_register(&(struct task_info) {
 400                 .name = "server command",
 401                 .pre_select = command_pre_select,
 402                 .post_select = command_post_select,
 403                 .context = sct,
 404         }, &sched);
 405         return;
 406 err:
 407         PARA_EMERG_LOG("%s\n", para_strerror(-ret));
 408         exit(EXIT_FAILURE);
 409 }
 410
 411 static int init_afs(int argc, char **argv)
 412 {
 413         int ret, afs_server_socket[2];
 414         pid_t afs_pid;
 415         char c;
 416
 417         ret = socketpair(PF_UNIX, SOCK_STREAM, 0, afs_server_socket);
 418         if (ret < 0)
 419                 exit(EXIT_FAILURE);
 420         get_random_bytes_or_die((unsigned char *)&afs_socket_cookie,
 421                 sizeof(afs_socket_cookie));
 422         afs_pid = fork();
 423         if (afs_pid < 0)
 424                 exit(EXIT_FAILURE);
 425         if (afs_pid == 0) { /* child (afs) */
 426                 int i;
 427
 428                 for (i = argc - 1; i >= 0; i--)
 429                         memset(argv[i], 0, strlen(argv[i]));
 430                 sprintf(argv[0], "para_server (afs)");
 431                 close(afs_server_socket[0]);
 432                 afs_init(afs_socket_cookie, afs_server_socket[1]);
 433         }
 434         mmd->afs_pid = afs_pid;
 435         close(afs_server_socket[1]);
 436         if (read(afs_server_socket[0], &c, 1) <= 0) {
 437                 PARA_EMERG_LOG("early afs exit\n");
 438                 exit(EXIT_FAILURE);
 439         }
 440         ret = mark_fd_nonblocking(afs_server_socket[0]);
 441         if (ret < 0)
 442                 exit(EXIT_FAILURE);
 443         add_close_on_fork_list(afs_server_socket[0]);
 444         PARA_INFO_LOG("afs_socket: %d, afs_socket_cookie: %u\n",
 445                 afs_server_socket[0], (unsigned) afs_socket_cookie);
 446         return afs_server_socket[0];
 447 }
 448
 449 __noreturn static void print_help_and_die(void)
 450 {
 451         struct ggo_help h = DEFINE_GGO_HELP(server);
 452         bool d = conf.detailed_help_given;
 453
 454         ggo_print_help(&h, d? GPH_STANDARD_FLAGS_DETAILED : GPH_STANDARD_FLAGS);
 455         exit(0);
 456 }
 457
 458 static void server_init(int argc, char **argv)
 459 {
 460         struct server_cmdline_parser_params params = {
 461                 .override = 0,
 462                 .initialize = 1,
 463                 .check_required = 0,
 464                 .check_ambiguity = 0,
 465                 .print_errors = 1
 466         };
 467         int afs_socket, daemon_pipe = -1;
 468
 469         valid_fd_012();
 470         init_random_seed_or_die();
 471         /* parse command line options */
 472         server_cmdline_parser_ext(argc, argv, &conf, &params);
 473         daemon_set_loglevel(conf.loglevel_arg);
 474         version_handle_flag("server", conf.version_given);
 475         if (conf.help_given || conf.detailed_help_given)
 476                 print_help_and_die();
 477         daemon_set_priority(conf.priority_arg);
 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("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                 daemon_pipe = daemonize(true /* parent waits for us */);
 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 (daemon_pipe >= 0) {
 514                 if (write(daemon_pipe, "\0", 1) < 0) {
 515                         PARA_EMERG_LOG("daemon_pipe: %s", strerror(errno));
 516                         exit(EXIT_FAILURE);
 517                 }
 518                 close(daemon_pipe);
 519         }
 520         PARA_NOTICE_LOG("server init complete\n");
 521 }
 522
 523 static void status_refresh(void)
 524 {
 525         static int prev_uptime = -1, prev_events = -1;
 526         int uptime = daemon_get_uptime(now);
 527
 528         if (prev_events != mmd->events)
 529                 goto out;
 530         if (mmd->new_vss_status_flags != mmd->vss_status_flags)
 531                 goto out_inc_events;
 532         if (uptime / 60 != prev_uptime / 60)
 533                 goto out_inc_events;
 534         return;
 535 out_inc_events:
 536         mmd->events++;
 537 out:
 538         prev_uptime = uptime;
 539         prev_events = mmd->events;
 540         mmd->vss_status_flags = mmd->new_vss_status_flags;
 541         PARA_DEBUG_LOG("%u events, forcing status update\n", mmd->events);
 542         killpg(0, SIGUSR1);
 543 }
 544
 545 static int server_select(int max_fileno, fd_set *readfds, fd_set *writefds,
 546                 struct timeval *timeout_tv)
 547 {
 548         int ret;
 549
 550         status_refresh();
 551         mutex_unlock(mmd_mutex);
 552         ret = para_select(max_fileno + 1, readfds, writefds, timeout_tv);
 553         mutex_lock(mmd_mutex);
 554         return ret;
 555 }
 556
 557 /**
 558  * The main function of para_server.
 559  *
 560  * \param argc Usual argument count.
 561  * \param argv Usual argument vector.
 562  *
 563  * \return EXIT_SUCCESS or EXIT_FAILURE.
 564  */
 565 int main(int argc, char *argv[])
 566 {
 567         int ret;
 568
 569         sched.default_timeout.tv_sec = 1;
 570         sched.select_function = server_select;
 571
 572         server_init(argc, argv);
 573         mutex_lock(mmd_mutex);
 574         ret = schedule(&sched);
 575         sched_shutdown(&sched);
 576         if (ret < 0) {
 577                 PARA_EMERG_LOG("%s\n", para_strerror(-ret));
 578                 exit(EXIT_FAILURE);
 579         }
 580         exit(EXIT_SUCCESS);
 581 }