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, \ref error2.c,
  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 __printf_2_3 void (*para_log)(int, const char*, ...) = daemon_log;
  69
  70 /** Define the array of error lists needed by para_server. */
  71 INIT_SERVER_ERRLISTS;
  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         daemon_init_colors_or_die(conf.color_arg, color_arg_auto, color_arg_no,
 211                 conf.logfile_given, conf.log_color_arg, conf.log_color_given);
 212         daemon_set_flag(DF_LOG_PID);
 213         daemon_set_flag(DF_LOG_LL);
 214         daemon_set_flag(DF_LOG_TIME);
 215         if (conf.log_timing_given)
 216                 daemon_set_flag(DF_LOG_TIMING);
 217         ret = 1;
 218 out:
 219         free(cf);
 220         free(home);
 221         if (ret > 0)
 222                 return;
 223         free(user_list_file);
 224         user_list_file = NULL;
 225         exit(EXIT_FAILURE);
 226 }
 227
 228 /*
 229  * called when server gets SIGHUP or when client invokes hup command.
 230  */
 231 static void handle_sighup(void)
 232 {
 233         PARA_NOTICE_LOG("SIGHUP\n");
 234         parse_config_or_die(1); /* reopens log */
 235         init_user_list(user_list_file); /* reload user list */
 236         if (mmd->afs_pid)
 237                 kill(mmd->afs_pid, SIGHUP);
 238 }
 239
 240 static int signal_post_select(struct sched *s, __a_unused void *context)
 241 {
 242         int signum = para_next_signal(&s->rfds);
 243
 244         switch (signum) {
 245         case 0:
 246                 return 0;
 247         case SIGHUP:
 248                 handle_sighup();
 249                 break;
 250         case SIGCHLD:
 251                 for (;;) {
 252                         pid_t pid;
 253                         int ret = para_reap_child(&pid);
 254                         if (ret <= 0)
 255                                 break;
 256                         if (pid != mmd->afs_pid)
 257                                 continue;
 258                         PARA_EMERG_LOG("fatal: afs died\n");
 259                         kill(0, SIGTERM);
 260                         goto cleanup;
 261                 }
 262                 break;
 263         /* die on sigint/sigterm. Kill all children too. */
 264         case SIGINT:
 265         case SIGTERM:
 266                 PARA_EMERG_LOG("terminating on signal %d\n", signum);
 267                 kill(0, SIGTERM);
 268                 /*
 269                  * We must wait for afs because afs catches SIGINT/SIGTERM.
 270                  * Before reacting to the signal, afs might want to use the
 271                  * shared memory area and the mmd mutex.  If we destroy this
 272                  * mutex too early and afs tries to lock the shared memory
 273                  * area, the call to mutex_lock() will fail and terminate the
 274                  * afs process. This leads to dirty osl tables.
 275                  *
 276                  * There's no such problem with the other children of the
 277                  * server process (the command handlers) as these reset their
 278                  * SIGINT/SIGTERM handlers to the default action, i.e.  these
 279                  * processes get killed immediately by the above kill().
 280                  */
 281                 PARA_INFO_LOG("waiting for afs (pid %d) to die\n",
 282                         (int)mmd->afs_pid);
 283                 waitpid(mmd->afs_pid, NULL, 0);
 284 cleanup:
 285                 free(mmd->afd.afhi.chunk_table);
 286                 close_listed_fds();
 287                 mutex_destroy(mmd_mutex);
 288                 shm_detach(mmd);
 289                 exit(EXIT_FAILURE);
 290         }
 291         return 0;
 292 }
 293
 294 static void init_signal_task(void)
 295 {
 296         signal_task = signal_init_or_die();
 297         para_install_sighandler(SIGINT);
 298         para_install_sighandler(SIGTERM);
 299         para_install_sighandler(SIGHUP);
 300         para_install_sighandler(SIGCHLD);
 301         para_sigaction(SIGPIPE, SIG_IGN);
 302         add_close_on_fork_list(signal_task->fd);
 303         signal_task->task = task_register(&(struct task_info) {
 304                 .name = "signal",
 305                 .pre_select = signal_pre_select,
 306                 .post_select = signal_post_select,
 307                 .context = signal_task,
 308
 309         }, &sched);
 310 }
 311
 312 static void command_pre_select(struct sched *s, void *context)
 313 {
 314         struct server_command_task *sct = context;
 315         para_fd_set(sct->listen_fd, &s->rfds, &s->max_fileno);
 316 }
 317
 318 static int command_post_select(struct sched *s, void *context)
 319 {
 320         struct server_command_task *sct = context;
 321
 322         int new_fd, ret, i;
 323         char *peer_name;
 324         pid_t child_pid;
 325         uint32_t *chunk_table;
 326
 327         ret = para_accept(sct->listen_fd, &s->rfds, NULL, 0, &new_fd);
 328         if (ret <= 0)
 329                 goto out;
 330         peer_name = remote_name(new_fd);
 331         PARA_INFO_LOG("got connection from %s, forking\n", peer_name);
 332         mmd->num_connects++;
 333         mmd->active_connections++;
 334         /*
 335          * The chunk table is a pointer located in the mmd struct that points
 336          * to dynamically allocated memory, i.e. it must be freed by the parent
 337          * and the child. However, as the mmd struct is in a shared memory
 338          * area, there's no guarantee that after the fork this pointer is still
 339          * valid in child context. As it is not used in the child anyway, we
 340          * save it to a local variable before the fork and free the memory via
 341          * that copy in the child directly after the fork.
 342          */
 343         chunk_table = mmd->afd.afhi.chunk_table;
 344         child_pid = fork();
 345         if (child_pid < 0) {
 346                 ret = -ERRNO_TO_PARA_ERROR(errno);
 347                 goto out;
 348         }
 349         if (child_pid) {
 350                 /* avoid problems with non-fork-safe PRNGs */
 351                 unsigned char buf[16];
 352                 get_random_bytes_or_die(buf, sizeof(buf));
 353                 close(new_fd);
 354                 /* parent keeps accepting connections */
 355                 return 0;
 356         }
 357         /* mmd might already have changed at this point */
 358         free(chunk_table);
 359         alarm(ALARM_TIMEOUT);
 360         close_listed_fds();
 361         signal_shutdown(signal_task);
 362         /*
 363          * put info on who we are serving into argv[0] to make
 364          * client ip visible in top/ps
 365          */
 366         for (i = sct->argc - 1; i >= 0; i--)
 367                 memset(sct->argv[i], 0, strlen(sct->argv[i]));
 368         sprintf(sct->argv[0], "para_server (serving %s)", peer_name);
 369         handle_connect(new_fd, peer_name);
 370         /* never reached*/
 371 out:
 372         if (ret < 0)
 373                 PARA_CRIT_LOG("%s\n", para_strerror(-ret));
 374         return 0;
 375 }
 376
 377 static void init_server_command_task(int argc, char **argv)
 378 {
 379         int ret;
 380         static struct server_command_task server_command_task_struct,
 381                 *sct = &server_command_task_struct;
 382
 383         PARA_NOTICE_LOG("initializing tcp command socket\n");
 384         sct->argc = argc;
 385         sct->argv = argv;
 386         ret = para_listen_simple(IPPROTO_TCP, conf.port_arg);
 387         if (ret < 0)
 388                 goto err;
 389         sct->listen_fd = ret;
 390         ret = mark_fd_nonblocking(sct->listen_fd);
 391         if (ret < 0)
 392                 goto err;
 393         add_close_on_fork_list(sct->listen_fd); /* child doesn't need the listener */
 394         sct->task = task_register(&(struct task_info) {
 395                 .name = "server command",
 396                 .pre_select = command_pre_select,
 397                 .post_select = command_post_select,
 398                 .context = sct,
 399         }, &sched);
 400         return;
 401 err:
 402         PARA_EMERG_LOG("%s\n", para_strerror(-ret));
 403         exit(EXIT_FAILURE);
 404 }
 405
 406 static int init_afs(int argc, char **argv)
 407 {
 408         int ret, afs_server_socket[2];
 409         pid_t afs_pid;
 410
 411         ret = socketpair(PF_UNIX, SOCK_DGRAM, 0, afs_server_socket);
 412         if (ret < 0)
 413                 exit(EXIT_FAILURE);
 414         get_random_bytes_or_die((unsigned char *)&afs_socket_cookie,
 415                 sizeof(afs_socket_cookie));
 416         afs_pid = fork();
 417         if (afs_pid < 0)
 418                 exit(EXIT_FAILURE);
 419         if (afs_pid == 0) { /* child (afs) */
 420                 int i;
 421                 for (i = argc - 1; i >= 0; i--)
 422                         memset(argv[i], 0, strlen(argv[i]));
 423                 sprintf(argv[0], "para_server (afs)");
 424                 close(afs_server_socket[0]);
 425                 afs_init(afs_socket_cookie, afs_server_socket[1]);
 426         }
 427         mmd->afs_pid = afs_pid;
 428         close(afs_server_socket[1]);
 429         ret = mark_fd_nonblocking(afs_server_socket[0]);
 430         if (ret < 0)
 431                 exit(EXIT_FAILURE);
 432         add_close_on_fork_list(afs_server_socket[0]);
 433         PARA_INFO_LOG("afs_socket: %d, afs_socket_cookie: %u\n",
 434                 afs_server_socket[0], (unsigned) afs_socket_cookie);
 435         return afs_server_socket[0];
 436 }
 437
 438 __noreturn static void print_help_and_die(void)
 439 {
 440         struct ggo_help h = DEFINE_GGO_HELP(server);
 441         bool d = conf.detailed_help_given;
 442
 443         ggo_print_help(&h, d? GPH_STANDARD_FLAGS_DETAILED : GPH_STANDARD_FLAGS);
 444         exit(0);
 445 }
 446
 447 static void server_init(int argc, char **argv)
 448 {
 449         struct server_cmdline_parser_params params = {
 450                 .override = 0,
 451                 .initialize = 1,
 452                 .check_required = 0,
 453                 .check_ambiguity = 0,
 454                 .print_errors = 1
 455         };
 456         int afs_socket;
 457
 458         valid_fd_012();
 459         init_random_seed_or_die();
 460         /* parse command line options */
 461         server_cmdline_parser_ext(argc, argv, &conf, &params);
 462         daemon_set_loglevel(conf.loglevel_arg);
 463         version_handle_flag("server", conf.version_given);
 464         if (conf.help_given || conf.detailed_help_given)
 465                 print_help_and_die();
 466         daemon_set_priority(conf.priority_arg);
 467         daemon_drop_privileges_or_die(conf.user_arg, conf.group_arg);
 468         /* parse config file, open log and set defaults */
 469         parse_config_or_die(0);
 470         daemon_log_welcome("server");
 471         init_ipc_or_die(); /* init mmd struct and mmd->lock */
 472         daemon_set_start_time();
 473         init_user_list(user_list_file);
 474         /* become daemon */
 475         if (conf.daemon_given)
 476                 daemonize(true /* parent waits for SIGTERM */);
 477         PARA_NOTICE_LOG("initializing audio format handlers\n");
 478         afh_init();
 479
 480         /*
 481          * Although afs uses its own signal handling we must ignore SIGUSR1
 482          * _before_ the afs child process gets born by init_afs() below.  It's
 483          * racy to do this in the child because the parent might send SIGUSR1
 484          * before the child gets a chance to ignore this signal -- only the
 485          * good die young.
 486          */
 487         para_sigaction(SIGUSR1, SIG_IGN);
 488         /*
 489          * We have to block SIGCHLD before the afs process is being forked off.
 490          * Otherwise, para_server does not notice if afs dies before the
 491          * SIGCHLD handler has been installed for the parent process by
 492          * init_signal_task() below.
 493          */
 494         para_block_signal(SIGCHLD);
 495         PARA_NOTICE_LOG("initializing the audio file selector\n");
 496         afs_socket = init_afs(argc, argv);
 497         init_signal_task();
 498         para_unblock_signal(SIGCHLD);
 499         PARA_NOTICE_LOG("initializing virtual streaming system\n");
 500         init_vss_task(afs_socket, &sched);
 501         init_server_command_task(argc, argv);
 502         if (conf.daemon_given)
 503                 kill(getppid(), SIGTERM);
 504         PARA_NOTICE_LOG("server init complete\n");
 505 }
 506
 507 static void status_refresh(void)
 508 {
 509         static int prev_uptime = -1, prev_events = -1;
 510         int uptime = daemon_get_uptime(now);
 511
 512         if (prev_events != mmd->events)
 513                 goto out;
 514         if (mmd->new_vss_status_flags != mmd->vss_status_flags)
 515                 goto out_inc_events;
 516         if (uptime / 60 != prev_uptime / 60)
 517                 goto out_inc_events;
 518         return;
 519 out_inc_events:
 520         mmd->events++;
 521 out:
 522         prev_uptime = uptime;
 523         prev_events = mmd->events;
 524         mmd->vss_status_flags = mmd->new_vss_status_flags;
 525         PARA_DEBUG_LOG("%d events, forcing status update\n", mmd->events);
 526         killpg(0, SIGUSR1);
 527 }
 528
 529 static int server_select(int max_fileno, fd_set *readfds, fd_set *writefds,
 530                 struct timeval *timeout_tv)
 531 {
 532         int ret;
 533
 534         status_refresh();
 535         mutex_unlock(mmd_mutex);
 536         ret = para_select(max_fileno + 1, readfds, writefds, timeout_tv);
 537         mutex_lock(mmd_mutex);
 538         return ret;
 539 }
 540
 541 /**
 542  * The main function of para_server.
 543  *
 544  * \param argc Usual argument count.
 545  * \param argv Usual argument vector.
 546  *
 547  * \return EXIT_SUCCESS or EXIT_FAILURE.
 548  */
 549 int main(int argc, char *argv[])
 550 {
 551         int ret;
 552
 553         sched.default_timeout.tv_sec = 1;
 554         sched.select_function = server_select;
 555
 556         server_init(argc, argv);
 557         mutex_lock(mmd_mutex);
 558         ret = schedule(&sched);
 559         sched_shutdown(&sched);
 560         if (ret < 0) {
 561                 PARA_EMERG_LOG("%s\n", para_strerror(-ret));
 562                 exit(EXIT_FAILURE);
 563         }
 564         exit(EXIT_SUCCESS);
 565 }