server: Cleanly shut down senders on exit.
[paraslash.git] / 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 "server.h"
49 #include "list.h"
50 #include "send.h"
51 #include "sched.h"
52 #include "vss.h"
53 #include "config.h"
54 #include "close_on_fork.h"
55 #include "net.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 the main server process (parent of afs and the command handlers). */
110 static pid_t server_pid;
111
112 /**
113 * Tell whether the executing process is a command handler.
114 *
115 * Cleanup on exit must be performed differently for command handlers.
116 *
117 * \return True if the pid of the executing process is neither the server pid
118 * nor the afs pid.
119 */
120 bool process_is_command_handler(void)
121 {
122 pid_t pid = getpid();
123
124 return pid != afs_pid && pid != server_pid;
125 }
126
127 /** The task responsible for server command handling. */
128 struct server_command_task {
129 /** TCP port on which para_server listens for connections. */
130 int listen_fd;
131 /* File descriptor for the accepted socket. */
132 int child_fd;
133 /** Copied from para_server's main function. */
134 int argc;
135 /** Argument vector passed to para_server's main function. */
136 char **argv;
137 /** The command task structure for scheduling. */
138 struct task *task;
139 };
140
141 /**
142 * Return the list of tasks for the server process.
143 *
144 * This is called from \a com_tasks(). The helper is necessary since command
145 * handlers can not access the scheduler structure directly.
146 *
147 * \return A dynamically allocated string that must be freed by the caller.
148 */
149 char *server_get_tasks(void)
150 {
151 return get_task_list(&sched);
152 }
153
154 /*
155 * setup shared memory area and get mutex for locking
156 */
157 static void init_ipc_or_die(void)
158 {
159 void *shm;
160 int shmid, ret = shm_new(sizeof(struct misc_meta_data));
161
162 if (ret < 0)
163 goto err_out;
164 shmid = ret;
165 ret = shm_attach(shmid, ATTACH_RW, &shm);
166 shm_destroy(shmid);
167 if (ret < 0)
168 goto err_out;
169 mmd = shm;
170
171 ret = mutex_new();
172 if (ret < 0)
173 goto err_out;
174 mmd_mutex = ret;
175
176 mmd->num_played = 0;
177 mmd->num_commands = 0;
178 mmd->events = 0;
179 mmd->num_connects = 0;
180 mmd->active_connections = 0;
181 mmd->vss_status_flags = VSS_NEXT;
182 mmd->new_vss_status_flags = VSS_NEXT;
183 return;
184 err_out:
185 PARA_EMERG_LOG("%s\n", para_strerror(-ret));
186 exit(EXIT_FAILURE);
187 }
188
189 /**
190 * (Re-)read the server configuration files.
191 *
192 * \param reload Whether config file overrides command line.
193 *
194 * This function also re-opens the logfile and the user list. On SIGHUP it is
195 * called from both server and afs context.
196 */
197 void parse_config_or_die(bool reload)
198 {
199 int ret;
200 char *cf = NULL, *errctx = NULL, *user_list_file = NULL;
201 void *map;
202 size_t sz;
203 int cf_argc;
204 char **cf_argv;
205 struct lls_parse_result *cf_lpr, *merged_lpr;
206 char *home = para_homedir();
207
208 if (OPT_GIVEN(CONFIG_FILE))
209 cf = para_strdup(OPT_STRING_VAL(CONFIG_FILE));
210 else
211 cf = make_message("%s/.paraslash/server.conf", home);
212 if (!mmd || getpid() != afs_pid) {
213 if (OPT_GIVEN(USER_LIST))
214 user_list_file = para_strdup(OPT_STRING_VAL(USER_LIST));
215 else
216 user_list_file = make_message("%s/.paraslash/server.users", home);
217 }
218 free(home);
219 ret = mmap_full_file(cf, O_RDONLY, &map, &sz, NULL);
220 if (ret < 0) {
221 if (ret != -E_EMPTY && ret != -ERRNO_TO_PARA_ERROR(ENOENT))
222 goto free_cf;
223 if (ret == -ERRNO_TO_PARA_ERROR(ENOENT) && OPT_GIVEN(CONFIG_FILE))
224 goto free_cf;
225 server_lpr = cmdline_lpr;
226 goto success;
227 }
228 ret = lls(lls_convert_config(map, sz, NULL, &cf_argv, &errctx));
229 para_munmap(map, sz);
230 if (ret < 0)
231 goto free_cf;
232 cf_argc = ret;
233 ret = lls(lls_parse(cf_argc, cf_argv, CMD_PTR, &cf_lpr, &errctx));
234 lls_free_argv(cf_argv);
235 if (ret < 0)
236 goto free_cf;
237 if (reload) /* config file overrides command line */
238 ret = lls(lls_merge(cf_lpr, cmdline_lpr, CMD_PTR, &merged_lpr,
239 &errctx));
240 else /* command line options override config file options */
241 ret = lls(lls_merge(cmdline_lpr, cf_lpr, CMD_PTR, &merged_lpr,
242 &errctx));
243 lls_free_parse_result(cf_lpr, CMD_PTR);
244 if (ret < 0)
245 goto free_cf;
246 if (server_lpr != cmdline_lpr)
247 lls_free_parse_result(server_lpr, CMD_PTR);
248 server_lpr = merged_lpr;
249 success:
250 daemon_set_loglevel(ENUM_STRING_VAL(LOGLEVEL));
251 if (OPT_GIVEN(LOGFILE)) {
252 daemon_set_logfile(OPT_STRING_VAL(LOGFILE));
253 daemon_open_log_or_die();
254 }
255 if (daemon_init_colors_or_die(OPT_UINT32_VAL(COLOR), COLOR_AUTO,
256 COLOR_NO, OPT_GIVEN(LOGFILE))) {
257 int i;
258 for (i = 0; i < OPT_GIVEN(LOG_COLOR); i++)
259 daemon_set_log_color_or_die(lls_string_val(i,
260 OPT_RESULT(LOG_COLOR)));
261 }
262 daemon_set_flag(DF_LOG_PID);
263 daemon_set_flag(DF_LOG_LL);
264 daemon_set_flag(DF_LOG_TIME);
265 if (OPT_GIVEN(LOG_TIMING))
266 daemon_set_flag(DF_LOG_TIMING);
267 daemon_set_priority(OPT_UINT32_VAL(PRIORITY));
268 if (user_list_file)
269 init_user_list(user_list_file);
270 ret = 1;
271 free_cf:
272 free(cf);
273 free(user_list_file);
274 if (ret < 0) {
275 if (errctx)
276 PARA_ERROR_LOG("%s\n", errctx);
277 free(errctx);
278 PARA_EMERG_LOG("%s\n", para_strerror(-ret));
279 exit(EXIT_FAILURE);
280 }
281 }
282
283 /*
284 * called when server gets SIGHUP or when client invokes hup command.
285 */
286 static void handle_sighup(void)
287 {
288
289 PARA_NOTICE_LOG("SIGHUP\n");
290 parse_config_or_die(true);
291 if (afs_pid != 0)
292 kill(afs_pid, SIGHUP);
293 }
294
295 static int signal_post_select(struct sched *s, __a_unused void *context)
296 {
297 int ret, signum;
298
299 ret = task_get_notification(signal_task->task);
300 if (ret < 0)
301 return ret;
302 signum = para_next_signal(&s->rfds);
303 switch (signum) {
304 case 0:
305 return 0;
306 case SIGHUP:
307 handle_sighup();
308 break;
309 case SIGCHLD:
310 for (;;) {
311 pid_t pid;
312 ret = para_reap_child(&pid);
313 if (ret <= 0)
314 break;
315 if (pid != afs_pid)
316 continue;
317 PARA_EMERG_LOG("fatal: afs died\n");
318 kill(0, SIGTERM);
319 goto cleanup;
320 }
321 break;
322 /* die on sigint/sigterm. Kill all children too. */
323 case SIGINT:
324 case SIGTERM:
325 PARA_EMERG_LOG("terminating on signal %d\n", signum);
326 kill(0, SIGTERM);
327 /*
328 * We must wait for afs because afs catches SIGINT/SIGTERM.
329 * Before reacting to the signal, afs might want to use the
330 * shared memory area and the mmd mutex. If we destroy this
331 * mutex too early and afs tries to lock the shared memory
332 * area, the call to mutex_lock() will fail and terminate the
333 * afs process. This leads to dirty osl tables.
334 *
335 * There's no such problem with the other children of the
336 * server process (the command handlers) as these reset their
337 * SIGINT/SIGTERM handlers to the default action, i.e. these
338 * processes get killed immediately by the above kill().
339 */
340 PARA_INFO_LOG("waiting for afs (pid %d) to die\n",
341 (int)afs_pid);
342 waitpid(afs_pid, NULL, 0);
343 cleanup:
344 free(mmd->afd.afhi.chunk_table);
345 close_listed_fds();
346 mutex_destroy(mmd_mutex);
347 shm_detach(mmd);
348 exit(EXIT_FAILURE);
349 }
350 return 0;
351 }
352
353 static void init_signal_task(void)
354 {
355 signal_task = signal_init_or_die();
356 para_install_sighandler(SIGINT);
357 para_install_sighandler(SIGTERM);
358 para_install_sighandler(SIGHUP);
359 para_install_sighandler(SIGCHLD);
360 para_sigaction(SIGPIPE, SIG_IGN);
361 add_close_on_fork_list(signal_task->fd);
362 signal_task->task = task_register(&(struct task_info) {
363 .name = "signal",
364 .pre_select = signal_pre_select,
365 .post_select = signal_post_select,
366 .context = signal_task,
367
368 }, &sched);
369 }
370
371 static void command_pre_select(struct sched *s, void *context)
372 {
373 struct server_command_task *sct = context;
374 para_fd_set(sct->listen_fd, &s->rfds, &s->max_fileno);
375 }
376
377 static int command_post_select(struct sched *s, void *context)
378 {
379 struct server_command_task *sct = context;
380 int new_fd, ret, i;
381 char *peer_name;
382 pid_t child_pid;
383 uint32_t *chunk_table;
384
385 ret = task_get_notification(sct->task);
386 if (ret < 0)
387 return ret;
388 ret = para_accept(sct->listen_fd, &s->rfds, NULL, 0, &new_fd);
389 if (ret <= 0)
390 goto out;
391 mmd->num_connects++;
392 mmd->active_connections++;
393 /*
394 * The chunk table is a pointer located in the mmd struct that points
395 * to dynamically allocated memory, i.e. it must be freed by the parent
396 * and the child. However, as the mmd struct is in a shared memory
397 * area, there's no guarantee that after the fork this pointer is still
398 * valid in child context. As it is not used in the child anyway, we
399 * save it to a local variable before the fork and free the memory via
400 * that copy in the child directly after the fork.
401 */
402 chunk_table = mmd->afd.afhi.chunk_table;
403 child_pid = fork();
404 if (child_pid < 0) {
405 ret = -ERRNO_TO_PARA_ERROR(errno);
406 goto out;
407 }
408 if (child_pid) {
409 /* avoid problems with non-fork-safe PRNGs */
410 unsigned char buf[16];
411 get_random_bytes_or_die(buf, sizeof(buf));
412 close(new_fd);
413 /* parent keeps accepting connections */
414 return 0;
415 }
416 peer_name = remote_name(new_fd);
417 PARA_INFO_LOG("accepted connection from %s\n", peer_name);
418 /* mmd might already have changed at this point */
419 free(chunk_table);
420 sct->child_fd = new_fd;
421 /*
422 * put info on who we are serving into argv[0] to make
423 * client ip visible in top/ps
424 */
425 for (i = sct->argc - 1; i >= 0; i--)
426 memset(sct->argv[i], 0, strlen(sct->argv[i]));
427 i = sct->argc - 1 - lls_num_inputs(cmdline_lpr);
428 sprintf(sct->argv[i], "para_server (serving %s)", peer_name);
429 /* ask other tasks to terminate */
430 task_notify_all(s, E_CHILD_CONTEXT);
431 /*
432 * After we return, the scheduler calls server_select() with a minimal
433 * timeout value, because the remaining tasks have a notification
434 * pending. Next it calls the ->post_select method of these tasks,
435 * which will return negative in view of the notification. This causes
436 * schedule() to return as there are no more runnable tasks.
437 *
438 * Note that semaphores are not inherited across a fork(), so we don't
439 * hold the lock at this point. Since server_select() drops the lock
440 * prior to calling para_select(), we need to acquire it here.
441 */
442 mutex_lock(mmd_mutex);
443 return -E_CHILD_CONTEXT;
444 out:
445 if (ret < 0)
446 PARA_CRIT_LOG("%s\n", para_strerror(-ret));
447 return 0;
448 }
449
450 static void init_server_command_task(struct server_command_task *sct,
451 int argc, char **argv)
452 {
453 int ret;
454
455 PARA_NOTICE_LOG("initializing tcp command socket\n");
456 sct->child_fd = -1;
457 sct->argc = argc;
458 sct->argv = argv;
459 ret = para_listen_simple(IPPROTO_TCP, OPT_UINT32_VAL(PORT));
460 if (ret < 0)
461 goto err;
462 sct->listen_fd = ret;
463 ret = mark_fd_nonblocking(sct->listen_fd);
464 if (ret < 0)
465 goto err;
466 add_close_on_fork_list(sct->listen_fd); /* child doesn't need the listener */
467 sct->task = task_register(&(struct task_info) {
468 .name = "server command",
469 .pre_select = command_pre_select,
470 .post_select = command_post_select,
471 .context = sct,
472 }, &sched);
473 return;
474 err:
475 PARA_EMERG_LOG("%s\n", para_strerror(-ret));
476 exit(EXIT_FAILURE);
477 }
478
479 static int init_afs(int argc, char **argv)
480 {
481 int ret, afs_server_socket[2];
482 char c;
483
484 ret = socketpair(PF_UNIX, SOCK_STREAM, 0, afs_server_socket);
485 if (ret < 0)
486 exit(EXIT_FAILURE);
487 get_random_bytes_or_die((unsigned char *)&afs_socket_cookie,
488 sizeof(afs_socket_cookie));
489 afs_pid = fork();
490 if (afs_pid < 0)
491 exit(EXIT_FAILURE);
492 if (afs_pid == 0) { /* child (afs) */
493 int i;
494
495 afs_pid = getpid();
496 for (i = argc - 1; i >= 0; i--)
497 memset(argv[i], 0, strlen(argv[i]));
498 i = argc - lls_num_inputs(cmdline_lpr) - 1;
499 sprintf(argv[i], "para_server (afs)");
500 close(afs_server_socket[0]);
501 afs_init(afs_server_socket[1]);
502 }
503 close(afs_server_socket[1]);
504 if (read(afs_server_socket[0], &c, 1) <= 0) {
505 PARA_EMERG_LOG("early afs exit\n");
506 exit(EXIT_FAILURE);
507 }
508 ret = mark_fd_nonblocking(afs_server_socket[0]);
509 if (ret < 0)
510 exit(EXIT_FAILURE);
511 add_close_on_fork_list(afs_server_socket[0]);
512 PARA_INFO_LOG("afs_socket: %d, afs_socket_cookie: %u\n",
513 afs_server_socket[0], (unsigned) afs_socket_cookie);
514 return afs_server_socket[0];
515 }
516
517 static void handle_help_flags(void)
518 {
519 char *help;
520 bool d = OPT_GIVEN(DETAILED_HELP);
521
522 if (d)
523 help = lls_long_help(CMD_PTR);
524 else if (OPT_GIVEN(HELP))
525 help = lls_short_help(CMD_PTR);
526 else
527 return;
528 printf("%s\n", help);
529 free(help);
530 exit(EXIT_SUCCESS);
531 }
532
533 static void server_init(int argc, char **argv, struct server_command_task *sct)
534 {
535 int ret, afs_socket, daemon_pipe = -1;
536 char *errctx;
537
538 valid_fd_012();
539 /* parse command line options */
540 ret = lls(lls_parse(argc, argv, CMD_PTR, &cmdline_lpr, &errctx));
541 if (ret < 0)
542 goto fail;
543 server_lpr = cmdline_lpr;
544 daemon_set_loglevel(ENUM_STRING_VAL(LOGLEVEL));
545 daemon_drop_privileges_or_die(OPT_STRING_VAL(USER),
546 OPT_STRING_VAL(GROUP));
547 version_handle_flag("server", OPT_GIVEN(VERSION));
548 handle_help_flags();
549 parse_config_or_die(false);
550 /* become daemon */
551 if (OPT_GIVEN(DAEMON))
552 daemon_pipe = daemonize(true /* parent waits for SIGTERM */);
553 server_pid = getpid();
554 init_random_seed_or_die();
555 daemon_log_welcome("server");
556 init_ipc_or_die(); /* init mmd struct and mmd->lock */
557 daemon_set_start_time();
558 PARA_NOTICE_LOG("initializing audio format handlers\n");
559 afh_init();
560
561 /*
562 * Although afs uses its own signal handling we must ignore SIGUSR1
563 * _before_ the afs child process gets born by init_afs() below. It's
564 * racy to do this in the child because the parent might send SIGUSR1
565 * before the child gets a chance to ignore this signal.
566 *
567 * We also have to block SIGCHLD before the afs process is created
568 * because otherwise para_server does not notice if afs dies before the
569 * SIGCHLD handler has been installed for the parent process by
570 * init_signal_task() below.
571 */
572 para_sigaction(SIGUSR1, SIG_IGN);
573 para_block_signal(SIGCHLD);
574 PARA_NOTICE_LOG("initializing the audio file selector\n");
575 afs_socket = init_afs(argc, argv);
576 init_signal_task();
577 para_unblock_signal(SIGCHLD);
578 PARA_NOTICE_LOG("initializing virtual streaming system\n");
579 vss_init(afs_socket, &sched);
580 init_server_command_task(sct, argc, argv);
581 if (daemon_pipe >= 0) {
582 if (write(daemon_pipe, "\0", 1) < 0) {
583 PARA_EMERG_LOG("daemon_pipe: %s", strerror(errno));
584 exit(EXIT_FAILURE);
585 }
586 close(daemon_pipe);
587 }
588 PARA_NOTICE_LOG("server init complete\n");
589 return;
590 fail:
591 assert(ret < 0);
592 if (errctx)
593 PARA_ERROR_LOG("%s\n", errctx);
594 PARA_EMERG_LOG("%s\n", para_strerror(-ret));
595 exit(EXIT_FAILURE);
596 }
597
598 static void status_refresh(void)
599 {
600 static int prev_uptime = -1, prev_events = -1;
601 int uptime = daemon_get_uptime(now);
602
603 if (prev_events != mmd->events)
604 goto out;
605 if (mmd->new_vss_status_flags != mmd->vss_status_flags)
606 goto out_inc_events;
607 if (uptime / 60 != prev_uptime / 60)
608 goto out_inc_events;
609 return;
610 out_inc_events:
611 mmd->events++;
612 out:
613 prev_uptime = uptime;
614 prev_events = mmd->events;
615 mmd->vss_status_flags = mmd->new_vss_status_flags;
616 PARA_DEBUG_LOG("%u events, forcing status update\n", mmd->events);
617 killpg(0, SIGUSR1);
618 }
619
620 static int server_select(int max_fileno, fd_set *readfds, fd_set *writefds,
621 struct timeval *timeout_tv)
622 {
623 int ret;
624
625 status_refresh();
626 mutex_unlock(mmd_mutex);
627 ret = para_select(max_fileno + 1, readfds, writefds, timeout_tv);
628 mutex_lock(mmd_mutex);
629 return ret;
630 }
631
632 /**
633 * The main function of para_server.
634 *
635 * \param argc Usual argument count.
636 * \param argv Usual argument vector.
637 *
638 * \return EXIT_SUCCESS or EXIT_FAILURE.
639 */
640 int main(int argc, char *argv[])
641 {
642 int ret;
643 struct server_command_task server_command_task_struct,
644 *sct = &server_command_task_struct;
645
646 sched.default_timeout.tv_sec = 1;
647 sched.select_function = server_select;
648
649 server_init(argc, argv, sct);
650 mutex_lock(mmd_mutex);
651 ret = schedule(&sched);
652 sched_shutdown(&sched);
653 signal_shutdown(signal_task);
654 if (!process_is_command_handler()) { /* parent (server) */
655 if (ret < 0)
656 PARA_EMERG_LOG("%s\n", para_strerror(-ret));
657 } else {
658 /*
659 * We hold the mmd lock: it was re-acquired in server_select()
660 * after the select call.
661 */
662 mutex_unlock(mmd_mutex);
663 alarm(ALARM_TIMEOUT);
664 close_listed_fds();
665 ret = handle_connect(sct->child_fd);
666 }
667 vss_shutdown();
668 lls_free_parse_result(server_lpr, CMD_PTR);
669 if (server_lpr != cmdline_lpr)
670 lls_free_parse_result(cmdline_lpr, CMD_PTR);
671 exit(ret < 0? EXIT_FAILURE : EXIT_SUCCESS);
672 }