server.c

   1 /* Copyright (C) 1997 Andre Noll <maan@tuebingen.mpg.de>, see file COPYING. */
   2
   3 /** \file server.c Paraslash's main server. */
   4
   5 /**
   6  * \mainpage Main data structures and selected APIs:
   7  *
   8  *      - Senders: \ref sender,
   9  *      - Audio file selector: \ref afs_info, \ref afs_table,
  10  *      - Audio format handler: \ref audio_format_handler, \ref afh_info
  11  *      - Receivers/filters/writers: \ref receiver, \ref receiver_node,
  12  *        \ref filter, \ref filter_node, \ref writer_node, \ref writer.
  13  *      - Scheduling: \ref sched.h,
  14  *      - Buffer trees: \ref buffer_tree.h,
  15  *      - Sideband API: \ref sideband.h,
  16  *      - Crypto: \ref crypt.h, \ref crypt_backend.h,
  17  *      - Error subsystem: \ref error.h,
  18  *      - Inter process communication: \ref ipc.h,
  19  *      - Forward error correction: \ref fec.h,
  20  *      - Daemons: \ref daemon.h,
  21  *      - Mixer API: \ref mix.h,
  22  *      - Interactive sessions: \ref interactive.h,
  23  *      - File descriptors: \ref fd.h,
  24  *      - Signals: \ref signal.h,
  25  *      - Networking: \ref net.h,
  26  *      - Time: \ref time.c,
  27  *      - Doubly linked lists: \ref list.h.
  28  */
  29
  30 #include <netinet/in.h>
  31 #include <sys/socket.h>
  32 #include <signal.h>
  33 #include <regex.h>
  34 #include <osl.h>
  35 #include <sys/types.h>
  36 #include <arpa/inet.h>
  37 #include <sys/un.h>
  38 #include <netdb.h>
  39 #include <lopsub.h>
  40
  41 #include "server.lsg.h"
  42 #include "para.h"
  43 #include "error.h"
  44 #include "crypt.h"
  45 #include "afh.h"
  46 #include "string.h"
  47 #include "afs.h"
  48 #include "net.h"
  49 #include "server.h"
  50 #include "list.h"
  51 #include "send.h"
  52 #include "sched.h"
  53 #include "vss.h"
  54 #include "config.h"
  55 #include "close_on_fork.h"
  56 #include "daemon.h"
  57 #include "ipc.h"
  58 #include "fd.h"
  59 #include "signal.h"
  60 #include "user_list.h"
  61 #include "color.h"
  62 #include "version.h"
  63
  64 /** Array of error strings. */
  65 DEFINE_PARA_ERRLIST;
  66
  67 __printf_2_3 void (*para_log)(int, const char*, ...) = daemon_log;
  68
  69 /** Shut down non-authorized connections after that many seconds. */
  70 #define ALARM_TIMEOUT 10
  71
  72 /**
  73  * Pointer to shared memory area for communication between para_server
  74  * and its children. Exported to vss.c, command.c and to afs.
  75  */
  76 struct misc_meta_data *mmd;
  77
  78 /**
  79  * The active value for all config options of para_server.
  80  *
  81  * It is computed by merging the parse result of the command line options with
  82  * the parse result of the config file.
  83  */
  84 struct lls_parse_result *server_lpr = NULL;
  85
  86 /* Command line options (no config file options). Used in handle_sighup(). */
  87 static struct lls_parse_result *cmdline_lpr;
  88
  89 /**
  90  * A random number used to "authenticate" the afs connection.
  91  *
  92  * para_server picks this number by random before it forks the afs process. The
  93  * command handlers know this number as well and write it to the afs socket,
  94  * together with the id of the shared memory area which contains the payload of
  95  * the afs command. A local process has to know this number to abuse the afs
  96  * service provided by the local socket.
  97  */
  98 uint32_t afs_socket_cookie;
  99
 100 /** The mutex protecting the shared memory area containing the mmd struct. */
 101 int mmd_mutex;
 102
 103 static struct sched sched;
 104 static struct signal_task *signal_task;
 105
 106 /** The process id of the audio file selector process. */
 107 pid_t afs_pid = 0;
 108
 109 /** The task responsible for server command handling. */
 110 struct server_command_task {
 111         /** TCP port on which para_server listens for connections. */
 112         int listen_fd;
 113         /** Copied from para_server's main function. */
 114         int argc;
 115         /** Argument vector passed to para_server's main function. */
 116         char **argv;
 117         /** The command task structure for scheduling. */
 118         struct task *task;
 119 };
 120
 121 /**
 122  * Return the list of tasks for the server process.
 123  *
 124  * This is called from \a com_tasks(). The helper is necessary since command
 125  * handlers can not access the scheduler structure directly.
 126  *
 127  * \return A dynamically allocated string that must be freed by the caller.
 128  */
 129 char *server_get_tasks(void)
 130 {
 131         return get_task_list(&sched);
 132 }
 133
 134 /*
 135  * setup shared memory area and get mutex for locking
 136  */
 137 static void init_ipc_or_die(void)
 138 {
 139         void *shm;
 140         int shmid, ret = shm_new(sizeof(struct misc_meta_data));
 141
 142         if (ret < 0)
 143                 goto err_out;
 144         shmid = ret;
 145         ret = shm_attach(shmid, ATTACH_RW, &shm);
 146         shm_destroy(shmid);
 147         if (ret < 0)
 148                 goto err_out;
 149         mmd = shm;
 150
 151         ret = mutex_new();
 152         if (ret < 0)
 153                 goto err_out;
 154         mmd_mutex = ret;
 155
 156         mmd->num_played = 0;
 157         mmd->num_commands = 0;
 158         mmd->events = 0;
 159         mmd->num_connects = 0;
 160         mmd->active_connections = 0;
 161         mmd->vss_status_flags = VSS_NEXT;
 162         mmd->new_vss_status_flags = VSS_NEXT;
 163         return;
 164 err_out:
 165         PARA_EMERG_LOG("%s\n", para_strerror(-ret));
 166         exit(EXIT_FAILURE);
 167 }
 168
 169 /**
 170  * (Re-)read the server configuration files.
 171  *
 172  * \param reload Whether config file overrides command line.
 173  *
 174  * This function also re-opens the logfile and the user list. On SIGHUP it is
 175  * called from both server and afs context.
 176  */
 177 void parse_config_or_die(bool reload)
 178 {
 179         int ret;
 180         char *cf = NULL, *errctx = NULL, *user_list_file = NULL;
 181         void *map;
 182         size_t sz;
 183         int cf_argc;
 184         char **cf_argv;
 185         struct lls_parse_result *cf_lpr, *merged_lpr;
 186         char *home = para_homedir();
 187
 188         if (OPT_GIVEN(CONFIG_FILE))
 189                 cf = para_strdup(OPT_STRING_VAL(CONFIG_FILE));
 190         else
 191                 cf = make_message("%s/.paraslash/server.conf", home);
 192         if (!mmd || getpid() != afs_pid) {
 193                 if (OPT_GIVEN(USER_LIST))
 194                         user_list_file = para_strdup(OPT_STRING_VAL(USER_LIST));
 195                 else
 196                         user_list_file = make_message("%s/.paraslash/server.users", home);
 197         }
 198         free(home);
 199         ret = mmap_full_file(cf, O_RDONLY, &map, &sz, NULL);
 200         if (ret < 0) {
 201                 if (ret != -E_EMPTY && ret != -ERRNO_TO_PARA_ERROR(ENOENT))
 202                         goto free_cf;
 203                 if (ret == -ERRNO_TO_PARA_ERROR(ENOENT) && OPT_GIVEN(CONFIG_FILE))
 204                         goto free_cf;
 205                 server_lpr = cmdline_lpr;
 206                 goto success;
 207         }
 208         ret = lls(lls_convert_config(map, sz, NULL, &cf_argv, &errctx));
 209         para_munmap(map, sz);
 210         if (ret < 0)
 211                 goto free_cf;
 212         cf_argc = ret;
 213         ret = lls(lls_parse(cf_argc, cf_argv, CMD_PTR, &cf_lpr, &errctx));
 214         lls_free_argv(cf_argv);
 215         if (ret < 0)
 216                 goto free_cf;
 217         if (reload) /* config file overrides command line */
 218                 ret = lls(lls_merge(cf_lpr, cmdline_lpr, CMD_PTR, &merged_lpr,
 219                         &errctx));
 220         else /* command line options override config file options */
 221                 ret = lls(lls_merge(cmdline_lpr, cf_lpr, CMD_PTR, &merged_lpr,
 222                         &errctx));
 223         lls_free_parse_result(cf_lpr, CMD_PTR);
 224         if (ret < 0)
 225                 goto free_cf;
 226         if (server_lpr != cmdline_lpr)
 227                 lls_free_parse_result(server_lpr, CMD_PTR);
 228         server_lpr = merged_lpr;
 229 success:
 230         daemon_set_loglevel(ENUM_STRING_VAL(LOGLEVEL));
 231         if (OPT_GIVEN(LOGFILE)) {
 232                 daemon_set_logfile(OPT_STRING_VAL(LOGFILE));
 233                 daemon_open_log_or_die();
 234         }
 235         if (daemon_init_colors_or_die(OPT_UINT32_VAL(COLOR), COLOR_AUTO,
 236                         COLOR_NO, OPT_GIVEN(LOGFILE))) {
 237                 int i;
 238                 for (i = 0; i < OPT_GIVEN(LOG_COLOR); i++)
 239                         daemon_set_log_color_or_die(lls_string_val(i,
 240                                 OPT_RESULT(LOG_COLOR)));
 241         }
 242         daemon_set_flag(DF_LOG_PID);
 243         daemon_set_flag(DF_LOG_LL);
 244         daemon_set_flag(DF_LOG_TIME);
 245         if (OPT_GIVEN(LOG_TIMING))
 246                 daemon_set_flag(DF_LOG_TIMING);
 247         daemon_set_priority(OPT_UINT32_VAL(PRIORITY));
 248         if (user_list_file)
 249                 init_user_list(user_list_file);
 250         ret = 1;
 251 free_cf:
 252         free(cf);
 253         free(user_list_file);
 254         if (ret < 0) {
 255                 if (errctx)
 256                         PARA_ERROR_LOG("%s\n", errctx);
 257                 free(errctx);
 258                 PARA_EMERG_LOG("%s\n", para_strerror(-ret));
 259                 exit(EXIT_FAILURE);
 260         }
 261 }
 262
 263 /*
 264  * called when server gets SIGHUP or when client invokes hup command.
 265  */
 266 static void handle_sighup(void)
 267 {
 268
 269         PARA_NOTICE_LOG("SIGHUP\n");
 270         parse_config_or_die(true);
 271         if (afs_pid != 0)
 272                 kill(afs_pid, SIGHUP);
 273 }
 274
 275 static int signal_post_select(struct sched *s, __a_unused void *context)
 276 {
 277         int signum = para_next_signal(&s->rfds);
 278
 279         switch (signum) {
 280         case 0:
 281                 return 0;
 282         case SIGHUP:
 283                 handle_sighup();
 284                 break;
 285         case SIGCHLD:
 286                 for (;;) {
 287                         pid_t pid;
 288                         int ret = para_reap_child(&pid);
 289                         if (ret <= 0)
 290                                 break;
 291                         if (pid != afs_pid)
 292                                 continue;
 293                         PARA_EMERG_LOG("fatal: afs died\n");
 294                         kill(0, SIGTERM);
 295                         goto cleanup;
 296                 }
 297                 break;
 298         /* die on sigint/sigterm. Kill all children too. */
 299         case SIGINT:
 300         case SIGTERM:
 301                 PARA_EMERG_LOG("terminating on signal %d\n", signum);
 302                 kill(0, SIGTERM);
 303                 /*
 304                  * We must wait for afs because afs catches SIGINT/SIGTERM.
 305                  * Before reacting to the signal, afs might want to use the
 306                  * shared memory area and the mmd mutex.  If we destroy this
 307                  * mutex too early and afs tries to lock the shared memory
 308                  * area, the call to mutex_lock() will fail and terminate the
 309                  * afs process. This leads to dirty osl tables.
 310                  *
 311                  * There's no such problem with the other children of the
 312                  * server process (the command handlers) as these reset their
 313                  * SIGINT/SIGTERM handlers to the default action, i.e.  these
 314                  * processes get killed immediately by the above kill().
 315                  */
 316                 PARA_INFO_LOG("waiting for afs (pid %d) to die\n",
 317                         (int)afs_pid);
 318                 waitpid(afs_pid, NULL, 0);
 319 cleanup:
 320                 free(mmd->afd.afhi.chunk_table);
 321                 close_listed_fds();
 322                 mutex_destroy(mmd_mutex);
 323                 shm_detach(mmd);
 324                 exit(EXIT_FAILURE);
 325         }
 326         return 0;
 327 }
 328
 329 static void init_signal_task(void)
 330 {
 331         signal_task = signal_init_or_die();
 332         para_install_sighandler(SIGINT);
 333         para_install_sighandler(SIGTERM);
 334         para_install_sighandler(SIGHUP);
 335         para_install_sighandler(SIGCHLD);
 336         para_sigaction(SIGPIPE, SIG_IGN);
 337         add_close_on_fork_list(signal_task->fd);
 338         signal_task->task = task_register(&(struct task_info) {
 339                 .name = "signal",
 340                 .pre_select = signal_pre_select,
 341                 .post_select = signal_post_select,
 342                 .context = signal_task,
 343
 344         }, &sched);
 345 }
 346
 347 static void command_pre_select(struct sched *s, void *context)
 348 {
 349         struct server_command_task *sct = context;
 350         para_fd_set(sct->listen_fd, &s->rfds, &s->max_fileno);
 351 }
 352
 353 static int command_post_select(struct sched *s, void *context)
 354 {
 355         struct server_command_task *sct = context;
 356
 357         int new_fd, ret, i;
 358         char *peer_name;
 359         pid_t child_pid;
 360         uint32_t *chunk_table;
 361
 362         ret = para_accept(sct->listen_fd, &s->rfds, NULL, 0, &new_fd);
 363         if (ret <= 0)
 364                 goto out;
 365         mmd->num_connects++;
 366         mmd->active_connections++;
 367         /*
 368          * The chunk table is a pointer located in the mmd struct that points
 369          * to dynamically allocated memory, i.e. it must be freed by the parent
 370          * and the child. However, as the mmd struct is in a shared memory
 371          * area, there's no guarantee that after the fork this pointer is still
 372          * valid in child context. As it is not used in the child anyway, we
 373          * save it to a local variable before the fork and free the memory via
 374          * that copy in the child directly after the fork.
 375          */
 376         chunk_table = mmd->afd.afhi.chunk_table;
 377         child_pid = fork();
 378         if (child_pid < 0) {
 379                 ret = -ERRNO_TO_PARA_ERROR(errno);
 380                 goto out;
 381         }
 382         if (child_pid) {
 383                 /* avoid problems with non-fork-safe PRNGs */
 384                 unsigned char buf[16];
 385                 get_random_bytes_or_die(buf, sizeof(buf));
 386                 close(new_fd);
 387                 /* parent keeps accepting connections */
 388                 return 0;
 389         }
 390         peer_name = remote_name(new_fd);
 391         PARA_INFO_LOG("accepted connection from %s\n", peer_name);
 392         /* mmd might already have changed at this point */
 393         free(chunk_table);
 394         alarm(ALARM_TIMEOUT);
 395         close_listed_fds();
 396         signal_shutdown(signal_task);
 397         /*
 398          * put info on who we are serving into argv[0] to make
 399          * client ip visible in top/ps
 400          */
 401         for (i = sct->argc - 1; i >= 0; i--)
 402                 memset(sct->argv[i], 0, strlen(sct->argv[i]));
 403         i = sct->argc - 1 - lls_num_inputs(cmdline_lpr);
 404         sprintf(sct->argv[i], "para_server (serving %s)", peer_name);
 405         handle_connect(new_fd);
 406         /* never reached*/
 407 out:
 408         if (ret < 0)
 409                 PARA_CRIT_LOG("%s\n", para_strerror(-ret));
 410         return 0;
 411 }
 412
 413 static void init_server_command_task(int argc, char **argv)
 414 {
 415         int ret;
 416         static struct server_command_task server_command_task_struct,
 417                 *sct = &server_command_task_struct;
 418
 419         PARA_NOTICE_LOG("initializing tcp command socket\n");
 420         sct->argc = argc;
 421         sct->argv = argv;
 422         ret = para_listen_simple(IPPROTO_TCP, OPT_UINT32_VAL(PORT));
 423         if (ret < 0)
 424                 goto err;
 425         sct->listen_fd = ret;
 426         ret = mark_fd_nonblocking(sct->listen_fd);
 427         if (ret < 0)
 428                 goto err;
 429         add_close_on_fork_list(sct->listen_fd); /* child doesn't need the listener */
 430         sct->task = task_register(&(struct task_info) {
 431                 .name = "server command",
 432                 .pre_select = command_pre_select,
 433                 .post_select = command_post_select,
 434                 .context = sct,
 435         }, &sched);
 436         return;
 437 err:
 438         PARA_EMERG_LOG("%s\n", para_strerror(-ret));
 439         exit(EXIT_FAILURE);
 440 }
 441
 442 static int init_afs(int argc, char **argv)
 443 {
 444         int ret, afs_server_socket[2];
 445         char c;
 446
 447         ret = socketpair(PF_UNIX, SOCK_STREAM, 0, afs_server_socket);
 448         if (ret < 0)
 449                 exit(EXIT_FAILURE);
 450         get_random_bytes_or_die((unsigned char *)&afs_socket_cookie,
 451                 sizeof(afs_socket_cookie));
 452         afs_pid = fork();
 453         if (afs_pid < 0)
 454                 exit(EXIT_FAILURE);
 455         if (afs_pid == 0) { /* child (afs) */
 456                 int i;
 457
 458                 afs_pid = getpid();
 459                 crypt_shutdown();
 460                 for (i = argc - 1; i >= 0; i--)
 461                         memset(argv[i], 0, strlen(argv[i]));
 462                 i = argc - lls_num_inputs(cmdline_lpr) - 1;
 463                 sprintf(argv[i], "para_server (afs)");
 464                 close(afs_server_socket[0]);
 465                 afs_init(afs_server_socket[1]);
 466         }
 467         close(afs_server_socket[1]);
 468         if (read(afs_server_socket[0], &c, 1) <= 0) {
 469                 PARA_EMERG_LOG("early afs exit\n");
 470                 exit(EXIT_FAILURE);
 471         }
 472         ret = mark_fd_nonblocking(afs_server_socket[0]);
 473         if (ret < 0)
 474                 exit(EXIT_FAILURE);
 475         add_close_on_fork_list(afs_server_socket[0]);
 476         PARA_INFO_LOG("afs_socket: %d, afs_socket_cookie: %u\n",
 477                 afs_server_socket[0], (unsigned) afs_socket_cookie);
 478         return afs_server_socket[0];
 479 }
 480
 481 static void handle_help_flags(void)
 482 {
 483         char *help;
 484         bool d = OPT_GIVEN(DETAILED_HELP);
 485
 486         if (d)
 487                 help = lls_long_help(CMD_PTR);
 488         else if (OPT_GIVEN(HELP))
 489                 help = lls_short_help(CMD_PTR);
 490         else
 491                 return;
 492         printf("%s\n", help);
 493         free(help);
 494         exit(EXIT_SUCCESS);
 495 }
 496
 497 static void server_init(int argc, char **argv)
 498 {
 499         int ret, afs_socket, daemon_pipe = -1;
 500         char *errctx;
 501
 502         valid_fd_012();
 503         /* parse command line options */
 504         ret = lls(lls_parse(argc, argv, CMD_PTR, &cmdline_lpr, &errctx));
 505         if (ret < 0)
 506                 goto fail;
 507         server_lpr = cmdline_lpr;
 508         daemon_set_loglevel(ENUM_STRING_VAL(LOGLEVEL));
 509         daemon_drop_privileges_or_die(OPT_STRING_VAL(USER),
 510                 OPT_STRING_VAL(GROUP));
 511         version_handle_flag("server", OPT_GIVEN(VERSION));
 512         handle_help_flags();
 513         parse_config_or_die(false);
 514         /* become daemon */
 515         if (OPT_GIVEN(DAEMON))
 516                 daemon_pipe = daemonize(true /* parent waits for SIGTERM */);
 517         crypt_init();
 518         daemon_log_welcome("server");
 519         init_ipc_or_die(); /* init mmd struct and mmd->lock */
 520         daemon_set_start_time();
 521         PARA_NOTICE_LOG("initializing audio format handlers\n");
 522         afh_init();
 523
 524         /*
 525          * Although afs uses its own signal handling we must ignore SIGUSR1
 526          * _before_ the afs child process gets born by init_afs() below.  It's
 527          * racy to do this in the child because the parent might send SIGUSR1
 528          * before the child gets a chance to ignore this signal.
 529          *
 530          * We also have to block SIGCHLD before the afs process is created
 531          * because otherwise para_server does not notice if afs dies before the
 532          * SIGCHLD handler has been installed for the parent process by
 533          * init_signal_task() below.
 534          */
 535         para_sigaction(SIGUSR1, SIG_IGN);
 536         para_block_signal(SIGCHLD);
 537         PARA_NOTICE_LOG("initializing the audio file selector\n");
 538         afs_socket = init_afs(argc, argv);
 539         init_signal_task();
 540         para_unblock_signal(SIGCHLD);
 541         PARA_NOTICE_LOG("initializing virtual streaming system\n");
 542         vss_init(afs_socket, &sched);
 543         init_server_command_task(argc, argv);
 544         if (daemon_pipe >= 0) {
 545                 if (write(daemon_pipe, "\0", 1) < 0) {
 546                         PARA_EMERG_LOG("daemon_pipe: %s", strerror(errno));
 547                         exit(EXIT_FAILURE);
 548                 }
 549                 close(daemon_pipe);
 550         }
 551         PARA_NOTICE_LOG("server init complete\n");
 552         return;
 553 fail:
 554         assert(ret < 0);
 555         if (errctx)
 556                 PARA_ERROR_LOG("%s\n", errctx);
 557         PARA_EMERG_LOG("%s\n", para_strerror(-ret));
 558         exit(EXIT_FAILURE);
 559 }
 560
 561 static void status_refresh(void)
 562 {
 563         static int prev_uptime = -1, prev_events = -1;
 564         int uptime = daemon_get_uptime(now);
 565
 566         if (prev_events != mmd->events)
 567                 goto out;
 568         if (mmd->new_vss_status_flags != mmd->vss_status_flags)
 569                 goto out_inc_events;
 570         if (uptime / 60 != prev_uptime / 60)
 571                 goto out_inc_events;
 572         return;
 573 out_inc_events:
 574         mmd->events++;
 575 out:
 576         prev_uptime = uptime;
 577         prev_events = mmd->events;
 578         mmd->vss_status_flags = mmd->new_vss_status_flags;
 579         PARA_DEBUG_LOG("%u events, forcing status update\n", mmd->events);
 580         killpg(0, SIGUSR1);
 581 }
 582
 583 static int server_select(int max_fileno, fd_set *readfds, fd_set *writefds,
 584                 struct timeval *timeout_tv)
 585 {
 586         int ret;
 587
 588         status_refresh();
 589         mutex_unlock(mmd_mutex);
 590         ret = para_select(max_fileno + 1, readfds, writefds, timeout_tv);
 591         mutex_lock(mmd_mutex);
 592         return ret;
 593 }
 594
 595 /**
 596  * The main function of para_server.
 597  *
 598  * \param argc Usual argument count.
 599  * \param argv Usual argument vector.
 600  *
 601  * \return EXIT_SUCCESS or EXIT_FAILURE.
 602  */
 603 int main(int argc, char *argv[])
 604 {
 605         int ret;
 606
 607         sched.default_timeout.tv_sec = 1;
 608         sched.select_function = server_select;
 609
 610         server_init(argc, argv);
 611         mutex_lock(mmd_mutex);
 612         ret = schedule(&sched);
 613         sched_shutdown(&sched);
 614         crypt_shutdown();
 615         lls_free_parse_result(server_lpr, CMD_PTR);
 616         if (server_lpr != cmdline_lpr)
 617                 lls_free_parse_result(cmdline_lpr, CMD_PTR);
 618         if (ret < 0)
 619                 PARA_EMERG_LOG("%s\n", para_strerror(-ret));
 620         exit(ret < 0? EXIT_FAILURE : EXIT_SUCCESS);
 621 }