Merge branch 'maint'
[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 #include <netinet/in.h>
6 #include <sys/socket.h>
7 #include <signal.h>
8 #include <regex.h>
9 #include <osl.h>
10 #include <sys/types.h>
11 #include <arpa/inet.h>
12 #include <sys/un.h>
13 #include <netdb.h>
14 #include <lopsub.h>
15
16 #include "server.lsg.h"
17 #include "para.h"
18 #include "error.h"
19 #include "lsu.h"
20 #include "crypt.h"
21 #include "afh.h"
22 #include "string.h"
23 #include "afs.h"
24 #include "net.h"
25 #include "server.h"
26 #include "list.h"
27 #include "sched.h"
28 #include "send.h"
29 #include "vss.h"
30 #include "config.h"
31 #include "close_on_fork.h"
32 #include "daemon.h"
33 #include "ipc.h"
34 #include "fd.h"
35 #include "signal.h"
36 #include "user_list.h"
37 #include "color.h"
38 #include "version.h"
39
40 /** Array of error strings. */
41 DEFINE_PARA_ERRLIST;
42
43 __printf_2_3 void (*para_log)(int, const char*, ...) = daemon_log;
44
45 /** Shut down non-authorized connections after that many seconds. */
46 #define ALARM_TIMEOUT 10
47
48 /**
49 * Pointer to shared memory area for communication between para_server
50 * and its children. Exported to vss.c, command.c and to afs.
51 */
52 struct misc_meta_data *mmd;
53
54 /**
55 * The active value for all config options of para_server.
56 *
57 * It is computed by merging the parse result of the command line options with
58 * the parse result of the config file.
59 */
60 struct lls_parse_result *server_lpr = NULL;
61
62 /* Command line options (no config file options). Used in handle_sighup(). */
63 static struct lls_parse_result *cmdline_lpr;
64
65 /**
66 * A random number used to "authenticate" the afs connection.
67 *
68 * para_server picks this number by random before it forks the afs process. The
69 * command handlers know this number as well and write it to the afs socket,
70 * together with the id of the shared memory area which contains the payload of
71 * the afs command. A local process has to know this number to abuse the afs
72 * service provided by the local socket.
73 */
74 uint32_t afs_socket_cookie;
75
76 /** The mutex protecting the shared memory area containing the mmd struct. */
77 int mmd_mutex;
78
79 /* Serializes log output. */
80 static int log_mutex;
81
82 static struct sched sched;
83 static struct signal_task *signal_task;
84
85 /** The process id of the audio file selector process. */
86 pid_t afs_pid = 0;
87
88 /* The main server process (parent of afs and the command handlers). */
89 static pid_t server_pid;
90
91 /**
92 * Tell whether the executing process is a command handler.
93 *
94 * Cleanup on exit must be performed differently for command handlers.
95 *
96 * \return True if the pid of the executing process is neither the server pid
97 * nor the afs pid.
98 */
99 bool process_is_command_handler(void)
100 {
101 pid_t pid = getpid();
102
103 return pid != afs_pid && pid != server_pid;
104 }
105
106 /** The task responsible for server command handling. */
107 struct server_command_task {
108 unsigned num_listen_fds; /* only one by default */
109 /** TCP socket(s) on which para_server listens for connections. */
110 int *listen_fds;
111 /* File descriptor for the accepted socket. */
112 int child_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 static void pre_log_hook(void)
135 {
136 mutex_lock(log_mutex);
137 }
138
139 static void post_log_hook(void)
140 {
141 mutex_unlock(log_mutex);
142 }
143
144 /* Setup shared memory area and init mutexes */
145 static void init_ipc_or_die(void)
146 {
147 void *shm;
148 int shmid, ret = shm_new(sizeof(struct misc_meta_data));
149
150 if (ret < 0)
151 goto err_out;
152 shmid = ret;
153 ret = shm_attach(shmid, ATTACH_RW, &shm);
154 shm_destroy(shmid);
155 if (ret < 0)
156 goto err_out;
157 mmd = shm;
158
159 ret = mutex_new();
160 if (ret < 0)
161 goto err_out;
162 mmd_mutex = ret;
163 ret = mutex_new();
164 if (ret < 0)
165 goto destroy_mmd_mutex;
166 log_mutex = ret;
167
168 mmd->num_played = 0;
169 mmd->num_commands = 0;
170 mmd->events = 0;
171 mmd->num_connects = 0;
172 mmd->active_connections = 0;
173 mmd->vss_status_flags = VSS_NEXT;
174 mmd->new_vss_status_flags = VSS_NEXT;
175 mmd->loglevel = OPT_UINT32_VAL(LOGLEVEL);
176 return;
177 destroy_mmd_mutex:
178 mutex_destroy(mmd_mutex);
179 err_out:
180 PARA_EMERG_LOG("%s\n", para_strerror(-ret));
181 exit(EXIT_FAILURE);
182 }
183
184 /** Get a reference to the supercommand of para_server. */
185 #define CMD_PTR (lls_cmd(0, server_suite))
186
187 /**
188 * (Re-)read the server configuration files.
189 *
190 * \param reload Whether config file overrides command line.
191 *
192 * This function also re-opens the logfile and the user list. On SIGHUP it is
193 * called from both server and afs context.
194 */
195 void parse_config_or_die(bool reload)
196 {
197 int ret;
198 unsigned flags = MCF_DONT_FREE;
199
200 if (server_lpr != cmdline_lpr)
201 lls_free_parse_result(server_lpr, CMD_PTR);
202 server_lpr = cmdline_lpr;
203 if (reload)
204 flags |= MCF_OVERRIDE;
205 ret = lsu_merge_config_file_options(OPT_STRING_VAL(CONFIG_FILE),
206 "server.conf", &server_lpr, CMD_PTR, server_suite, flags);
207 if (ret < 0) {
208 PARA_EMERG_LOG("failed to parse config file: %s\n",
209 para_strerror(-ret));
210 exit(EXIT_FAILURE);
211 }
212 daemon_set_loglevel(OPT_UINT32_VAL(LOGLEVEL));
213 if (OPT_GIVEN(LOGFILE)) {
214 daemon_set_logfile(OPT_STRING_VAL(LOGFILE));
215 daemon_open_log_or_die();
216 }
217 if (daemon_init_colors_or_die(OPT_UINT32_VAL(COLOR), COLOR_AUTO,
218 COLOR_NO, OPT_GIVEN(LOGFILE))) {
219 int i;
220 for (i = 0; i < OPT_GIVEN(LOG_COLOR); i++)
221 daemon_set_log_color_or_die(lls_string_val(i,
222 OPT_RESULT(LOG_COLOR)));
223 }
224 daemon_set_flag(DF_LOG_PID);
225 daemon_set_flag(DF_LOG_LL);
226 daemon_set_flag(DF_LOG_TIME);
227 if (OPT_GIVEN(LOG_TIMING))
228 daemon_set_flag(DF_LOG_TIMING);
229 daemon_set_priority(OPT_UINT32_VAL(PRIORITY));
230 if (!reload || getpid() != afs_pid) {
231 char *user_list_file;
232 if (OPT_GIVEN(USER_LIST))
233 user_list_file = para_strdup(OPT_STRING_VAL(USER_LIST));
234 else {
235 char *home = para_homedir();
236 user_list_file = make_message("%s/.paraslash/server.users", home);
237 free(home);
238 }
239 user_list_init(user_list_file);
240 free(user_list_file);
241 }
242 return;
243 }
244
245 /*
246 * called when server gets SIGHUP or when client invokes hup command.
247 */
248 static void handle_sighup(void)
249 {
250
251 PARA_NOTICE_LOG("SIGHUP\n");
252 parse_config_or_die(true);
253 if (afs_pid != 0)
254 kill(afs_pid, SIGHUP);
255 }
256
257 static int signal_post_monitor(struct sched *s, __a_unused void *context)
258 {
259 int ret, signum;
260
261 ret = task_get_notification(signal_task->task);
262 if (ret < 0)
263 return ret;
264 signum = para_next_signal();
265 switch (signum) {
266 case 0:
267 return 0;
268 case SIGHUP:
269 handle_sighup();
270 break;
271 case SIGCHLD:
272 for (;;) {
273 pid_t pid;
274 ret = para_reap_child(&pid);
275 if (ret <= 0)
276 break;
277 if (pid != afs_pid)
278 continue;
279 PARA_EMERG_LOG("fatal: afs died\n");
280 goto genocide;
281 }
282 break;
283 /* die on sigint/sigterm. Kill all children too. */
284 case SIGINT:
285 case SIGTERM:
286 PARA_EMERG_LOG("terminating on signal %d\n", signum);
287 genocide:
288 kill(0, SIGTERM);
289 /*
290 * We must wait for all of our children to die. For the afs
291 * process or a command handler might want to use the
292 * shared memory area and the mmd mutex. If we destroy this
293 * mutex too early and afs tries to lock the shared memory
294 * area, the call to mutex_lock() will fail and terminate the
295 * afs process. This leads to dirty osl tables.
296 */
297 PARA_INFO_LOG("waiting for child processes to die\n");
298 mutex_unlock(mmd_mutex);
299 while (wait(NULL) != -1 || errno != ECHILD)
300 ; /* still at least one child alive */
301 mutex_lock(mmd_mutex);
302 free(mmd->afd.afhi.chunk_table);
303 task_notify_all(s, E_DEADLY_SIGNAL);
304 return -E_DEADLY_SIGNAL;
305 }
306 return 0;
307 }
308
309 static void init_signal_task(void)
310 {
311 signal_task = signal_init_or_die();
312 para_install_sighandler(SIGINT);
313 para_install_sighandler(SIGTERM);
314 para_install_sighandler(SIGHUP);
315 para_install_sighandler(SIGCHLD);
316 para_sigaction(SIGPIPE, SIG_IGN);
317 add_close_on_fork_list(signal_task->fd);
318 signal_task->task = task_register(&(struct task_info) {
319 .name = "signal",
320 .pre_monitor = signal_pre_monitor,
321 .post_monitor = signal_post_monitor,
322 .context = signal_task,
323
324 }, &sched);
325 }
326
327 static void command_pre_monitor(struct sched *s, void *context)
328 {
329 unsigned n;
330 struct server_command_task *sct = context;
331
332 for (n = 0; n < sct->num_listen_fds; n++)
333 sched_monitor_readfd(sct->listen_fds[n], s);
334 }
335
336 static int command_task_accept(unsigned listen_idx, struct sched *s,
337 struct server_command_task *sct)
338 {
339 int new_fd, ret, i;
340 char *peer_name;
341 pid_t child_pid;
342 uint32_t *chunk_table;
343
344 ret = para_accept(sct->listen_fds[listen_idx], NULL, 0, &new_fd);
345 if (ret <= 0)
346 goto out;
347 mmd->num_connects++;
348 mmd->active_connections++;
349 /*
350 * The chunk table is a pointer located in the mmd struct that points
351 * to dynamically allocated memory, i.e. it must be freed by the parent
352 * and the child. However, as the mmd struct is in a shared memory
353 * area, there's no guarantee that after the fork this pointer is still
354 * valid in child context. As it is not used in the child anyway, we
355 * save it to a local variable before the fork and free the memory via
356 * that copy in the child directly after the fork.
357 */
358 chunk_table = mmd->afd.afhi.chunk_table;
359 child_pid = fork();
360 if (child_pid < 0) {
361 ret = -ERRNO_TO_PARA_ERROR(errno);
362 goto out;
363 }
364 if (child_pid) {
365 /* avoid problems with non-fork-safe PRNGs */
366 unsigned char buf[16];
367 get_random_bytes_or_die(buf, sizeof(buf));
368 close(new_fd);
369 /* parent keeps accepting connections */
370 return 0;
371 }
372 peer_name = remote_name(new_fd);
373 PARA_INFO_LOG("accepted connection from %s\n", peer_name);
374 /* mmd might already have changed at this point */
375 free(chunk_table);
376 sct->child_fd = new_fd;
377 /*
378 * put info on who we are serving into argv[0] to make
379 * client ip visible in top/ps
380 */
381 for (i = sct->argc - 1; i >= 0; i--)
382 memset(sct->argv[i], 0, strlen(sct->argv[i]));
383 i = sct->argc - 1 - lls_num_inputs(cmdline_lpr);
384 sprintf(sct->argv[i], "para_server (serving %s)", peer_name);
385 /* ask other tasks to terminate */
386 task_notify_all(s, E_CHILD_CONTEXT);
387 /*
388 * After we return, the scheduler calls server_select() with a minimal
389 * timeout value, because the remaining tasks have a notification
390 * pending. Next it calls the ->post_monitor method of these tasks,
391 * which will return negative in view of the notification. This causes
392 * schedule() to return as there are no more runnable tasks.
393 *
394 * Note that semaphores are not inherited across a fork(), so we don't
395 * hold the lock at this point. Since server_poll() drops the lock
396 * prior to calling poll(), we need to acquire it here.
397 */
398 mutex_lock(mmd_mutex);
399 return -E_CHILD_CONTEXT;
400 out:
401 if (ret < 0)
402 PARA_CRIT_LOG("%s\n", para_strerror(-ret));
403 return 0;
404 }
405
406 static int command_post_monitor(struct sched *s, void *context)
407 {
408 struct server_command_task *sct = context;
409 unsigned n;
410 int ret;
411
412 ret = task_get_notification(sct->task);
413 if (ret < 0)
414 goto fail;
415 for (n = 0; n < sct->num_listen_fds; n++) {
416 ret = command_task_accept(n, s, sct);
417 if (ret < 0)
418 goto fail;
419 }
420 return 0;
421 fail:
422 free(sct->listen_fds);
423 return ret;
424 }
425
426 static void init_server_command_task(struct server_command_task *sct,
427 int argc, char **argv)
428 {
429 int ret;
430 unsigned n;
431 uint32_t port = OPT_UINT32_VAL(PORT);
432
433 PARA_NOTICE_LOG("initializing tcp command socket\n");
434 sct->child_fd = -1;
435 sct->argc = argc;
436 sct->argv = argv;
437 if (!OPT_GIVEN(LISTEN_ADDRESS)) {
438 sct->num_listen_fds = 1;
439 sct->listen_fds = alloc(sizeof(int));
440 ret = para_listen_simple(IPPROTO_TCP, port);
441 if (ret < 0)
442 goto err;
443 sct->listen_fds[0] = ret;
444 } else {
445 sct->num_listen_fds = OPT_GIVEN(LISTEN_ADDRESS);
446 sct->listen_fds = alloc(sct->num_listen_fds * sizeof(int));
447 for (n = 0; n < OPT_GIVEN(LISTEN_ADDRESS); n++) {
448 const char *arg;
449 arg = lls_string_val(n, OPT_RESULT(LISTEN_ADDRESS));
450 ret = para_listen(IPPROTO_TCP, arg, port);
451 if (ret < 0)
452 goto err;
453 sct->listen_fds[n] = ret;
454 }
455 }
456 for (n = 0; n < sct->num_listen_fds; n++) {
457 ret = mark_fd_nonblocking(sct->listen_fds[n]);
458 if (ret < 0)
459 goto err;
460 /* child doesn't need the listener */
461 add_close_on_fork_list(sct->listen_fds[n]);
462 }
463
464 sct->task = task_register(&(struct task_info) {
465 .name = "server command",
466 .pre_monitor = command_pre_monitor,
467 .post_monitor = command_post_monitor,
468 .context = sct,
469 }, &sched);
470 /*
471 * Detect whether the abstract Unix domain socket space is supported,
472 * but do not create the socket. We check this once in server context
473 * so that the command handlers inherit this bit of information and
474 * don't need to check again.
475 */
476 create_local_socket(NULL);
477 return;
478 err:
479 PARA_EMERG_LOG("%s\n", para_strerror(-ret));
480 exit(EXIT_FAILURE);
481 }
482
483 static int init_afs(int argc, char **argv)
484 {
485 int ret, afs_server_socket[2];
486 char c;
487
488 ret = socketpair(PF_UNIX, SOCK_STREAM, 0, afs_server_socket);
489 if (ret < 0)
490 exit(EXIT_FAILURE);
491 get_random_bytes_or_die((unsigned char *)&afs_socket_cookie,
492 sizeof(afs_socket_cookie));
493 afs_pid = fork();
494 if (afs_pid < 0)
495 exit(EXIT_FAILURE);
496 if (afs_pid == 0) { /* child (afs) */
497 int i;
498
499 afs_pid = getpid();
500 crypt_shutdown();
501 user_list_deplete();
502 for (i = argc - 1; i >= 0; i--)
503 memset(argv[i], 0, strlen(argv[i]));
504 i = argc - lls_num_inputs(cmdline_lpr) - 1;
505 sprintf(argv[i], "para_server (afs)");
506 close(afs_server_socket[0]);
507 afs_init(afs_server_socket[1]);
508 }
509 close(afs_server_socket[1]);
510 if (read(afs_server_socket[0], &c, 1) <= 0) {
511 PARA_EMERG_LOG("early afs exit\n");
512 exit(EXIT_FAILURE);
513 }
514 ret = mark_fd_nonblocking(afs_server_socket[0]);
515 if (ret < 0)
516 exit(EXIT_FAILURE);
517 add_close_on_fork_list(afs_server_socket[0]);
518 PARA_INFO_LOG("afs_socket: %d, afs_socket_cookie: %u\n",
519 afs_server_socket[0], (unsigned) afs_socket_cookie);
520 return afs_server_socket[0];
521 }
522
523 static void handle_help_flags(void)
524 {
525 char *help;
526 bool d = OPT_GIVEN(DETAILED_HELP);
527
528 if (d)
529 help = lls_long_help(CMD_PTR);
530 else if (OPT_GIVEN(HELP))
531 help = lls_short_help(CMD_PTR);
532 else
533 return;
534 printf("%s\n", help);
535 free(help);
536 exit(EXIT_SUCCESS);
537 }
538
539 static void server_init(int argc, char **argv, struct server_command_task *sct)
540 {
541 int ret, afs_socket, daemon_pipe = -1;
542 char *errctx;
543
544 valid_fd_012();
545 /* parse command line options */
546 ret = lls(lls_parse(argc, argv, CMD_PTR, &cmdline_lpr, &errctx));
547 if (ret < 0)
548 goto fail;
549 server_lpr = cmdline_lpr;
550 daemon_set_loglevel(OPT_UINT32_VAL(LOGLEVEL));
551 daemon_drop_privileges_or_die(OPT_STRING_VAL(USER),
552 OPT_STRING_VAL(GROUP));
553 version_handle_flag("server", OPT_GIVEN(VERSION));
554 handle_help_flags();
555 parse_config_or_die(false);
556 /* become daemon */
557 if (OPT_GIVEN(DAEMON))
558 daemon_pipe = daemonize(true /* parent waits for SIGTERM */);
559 server_pid = getpid();
560 crypt_init();
561 daemon_log_welcome("server");
562 init_ipc_or_die(); /* init mmd struct, mmd and log mutex */
563 daemon_set_start_time();
564 daemon_set_hooks(pre_log_hook, post_log_hook);
565 /*
566 * Although afs uses its own signal handling we must ignore SIGUSR1
567 * _before_ the afs child process gets born by init_afs() below. It's
568 * racy to do this in the child because the parent might send SIGUSR1
569 * before the child gets a chance to ignore this signal.
570 *
571 * We also have to block SIGCHLD before the afs process is created
572 * because otherwise para_server does not notice if afs dies before the
573 * SIGCHLD handler has been installed for the parent process by
574 * init_signal_task() below.
575 */
576 para_sigaction(SIGUSR1, SIG_IGN);
577 para_block_signal(SIGCHLD);
578 PARA_NOTICE_LOG("initializing the audio file selector\n");
579 afs_socket = init_afs(argc, argv);
580 init_signal_task();
581 para_unblock_signal(SIGCHLD);
582 PARA_NOTICE_LOG("initializing virtual streaming system\n");
583 vss_init(afs_socket, &sched);
584 init_server_command_task(sct, argc, argv);
585 if (daemon_pipe >= 0) {
586 if (write(daemon_pipe, "\0", 1) < 0) {
587 PARA_EMERG_LOG("daemon_pipe: %s", strerror(errno));
588 exit(EXIT_FAILURE);
589 }
590 close(daemon_pipe);
591 }
592 PARA_NOTICE_LOG("server init complete\n");
593 return;
594 fail:
595 assert(ret < 0);
596 if (errctx)
597 PARA_ERROR_LOG("%s\n", errctx);
598 PARA_EMERG_LOG("%s\n", para_strerror(-ret));
599 exit(EXIT_FAILURE);
600 }
601
602 static void status_refresh(void)
603 {
604 static int prev_uptime = -1, prev_events = -1;
605 int uptime = daemon_get_uptime(now);
606
607 if (prev_events != mmd->events)
608 goto out;
609 if (mmd->new_vss_status_flags != mmd->vss_status_flags)
610 goto out_inc_events;
611 if (uptime / 60 != prev_uptime / 60)
612 goto out_inc_events;
613 return;
614 out_inc_events:
615 mmd->events++;
616 out:
617 prev_uptime = uptime;
618 prev_events = mmd->events;
619 mmd->vss_status_flags = mmd->new_vss_status_flags;
620 PARA_DEBUG_LOG("%u events, forcing status update\n", mmd->events);
621 killpg(0, SIGUSR1);
622 }
623
624 static int server_poll(struct pollfd *fds, nfds_t nfds, int timeout)
625 {
626 int ret;
627
628 daemon_set_loglevel(mmd->loglevel);
629 status_refresh();
630 mutex_unlock(mmd_mutex);
631 ret = xpoll(fds, nfds, timeout);
632 mutex_lock(mmd_mutex);
633 return ret;
634 }
635
636 /**
637 * Deallocate all lopsub parse results.
638 *
639 * The server allocates a parse result for command line options and optionally
640 * a second parse result for the effective configuration, defined by merging
641 * the command line options with the options stored in the configuration file.
642 * This function frees both structures.
643 */
644 void free_lpr(void)
645 {
646 lls_free_parse_result(server_lpr, CMD_PTR);
647 if (server_lpr != cmdline_lpr)
648 lls_free_parse_result(cmdline_lpr, CMD_PTR);
649 }
650
651 /**
652 * The main function of para_server.
653 *
654 * \param argc Usual argument count.
655 * \param argv Usual argument vector.
656 *
657 * \return EXIT_SUCCESS or EXIT_FAILURE.
658 */
659 int main(int argc, char *argv[])
660 {
661 int ret;
662 struct server_command_task server_command_task_struct,
663 *sct = &server_command_task_struct;
664
665 sched.default_timeout = 1000;
666 sched.poll_function = server_poll;
667
668 server_init(argc, argv, sct);
669 mutex_lock(mmd_mutex);
670 ret = schedule(&sched);
671 /*
672 * We hold the mmd lock: it was re-acquired in server_poll()
673 * after the poll(2) call.
674 */
675 mutex_unlock(mmd_mutex);
676 sched_shutdown(&sched);
677 crypt_shutdown();
678 signal_shutdown(signal_task);
679 if (!process_is_command_handler()) { /* parent (server) */
680 mutex_destroy(mmd_mutex);
681 daemon_set_hooks(NULL, NULL); /* only one process remaining */
682 mutex_destroy(log_mutex);
683 deplete_close_on_fork_list();
684 if (ret < 0)
685 PARA_EMERG_LOG("%s\n", para_strerror(-ret));
686 vss_shutdown();
687 } else {
688 vss_shutdown();
689 alarm(ALARM_TIMEOUT);
690 close_listed_fds();
691 ret = handle_connect(sct->child_fd);
692 }
693 shm_detach(mmd);
694 user_list_deplete();
695 free_lpr();
696 exit(ret < 0? EXIT_FAILURE : EXIT_SUCCESS);
697 }