1/* $OpenBSD: server.c,v 1.206 2024/05/14 10:11:09 nicm Exp $ */
2
3/*
4 * Copyright (c) 2007 Nicholas Marriott <nicholas.marriott@gmail.com>
5 *
6 * Permission to use, copy, modify, and distribute this software for any
7 * purpose with or without fee is hereby granted, provided that the above
8 * copyright notice and this permission notice appear in all copies.
9 *
10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
14 * WHATSOEVER RESULTING FROM LOSS OF MIND, USE, DATA OR PROFITS, WHETHER
15 * IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
16 * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
17 */
18
19#include <sys/types.h>
20#include <sys/ioctl.h>
21#include <sys/socket.h>
22#include <sys/stat.h>
23#include <sys/un.h>
24#include <sys/wait.h>
25
26#include <errno.h>
27#include <event.h>
28#include <fcntl.h>
29#include <paths.h>
30#include <signal.h>
31#include <stdio.h>
32#include <stdlib.h>
33#include <string.h>
34#include <termios.h>
35#include <time.h>
36#include <unistd.h>
37
38#include "tmux.h"
39
40/*
41 * Main server functions.
42 */
43
44struct clients		 clients;
45
46struct tmuxproc		*server_proc;
47static int		 server_fd = -1;
48static uint64_t		 server_client_flags;
49static int		 server_exit;
50static struct event	 server_ev_accept;
51static struct event	 server_ev_tidy;
52
53struct cmd_find_state	 marked_pane;
54
55static u_int		 message_next;
56struct message_list	 message_log;
57
58time_t			 current_time;
59
60static int	server_loop(void);
61static void	server_send_exit(void);
62static void	server_accept(int, short, void *);
63static void	server_signal(int);
64static void	server_child_signal(void);
65static void	server_child_exited(pid_t, int);
66static void	server_child_stopped(pid_t, int);
67
68/* Set marked pane. */
69void
70server_set_marked(struct session *s, struct winlink *wl, struct window_pane *wp)
71{
72	cmd_find_clear_state(&marked_pane, 0);
73	marked_pane.s = s;
74	marked_pane.wl = wl;
75	marked_pane.w = wl->window;
76	marked_pane.wp = wp;
77}
78
79/* Clear marked pane. */
80void
81server_clear_marked(void)
82{
83	cmd_find_clear_state(&marked_pane, 0);
84}
85
86/* Is this the marked pane? */
87int
88server_is_marked(struct session *s, struct winlink *wl, struct window_pane *wp)
89{
90	if (s == NULL || wl == NULL || wp == NULL)
91		return (0);
92	if (marked_pane.s != s || marked_pane.wl != wl)
93		return (0);
94	if (marked_pane.wp != wp)
95		return (0);
96	return (server_check_marked());
97}
98
99/* Check if the marked pane is still valid. */
100int
101server_check_marked(void)
102{
103	return (cmd_find_valid_state(&marked_pane));
104}
105
106/* Create server socket. */
107static int
108server_create_socket(int flags, char **cause)
109{
110	struct sockaddr_un	sa;
111	size_t			size;
112	mode_t			mask;
113	int			fd, saved_errno;
114
115	memset(&sa, 0, sizeof sa);
116	sa.sun_family = AF_UNIX;
117	size = strlcpy(sa.sun_path, socket_path, sizeof sa.sun_path);
118	if (size >= sizeof sa.sun_path) {
119		errno = ENAMETOOLONG;
120		goto fail;
121	}
122	unlink(sa.sun_path);
123
124	if ((fd = socket(AF_UNIX, SOCK_STREAM, 0)) == -1)
125		goto fail;
126
127	if (flags & CLIENT_DEFAULTSOCKET)
128		mask = umask(S_IXUSR|S_IXGRP|S_IRWXO);
129	else
130		mask = umask(S_IXUSR|S_IRWXG|S_IRWXO);
131	if (bind(fd, (struct sockaddr *)&sa, sizeof sa) == -1) {
132		saved_errno = errno;
133		close(fd);
134		errno = saved_errno;
135		goto fail;
136	}
137	umask(mask);
138
139	if (listen(fd, 128) == -1) {
140		saved_errno = errno;
141		close(fd);
142		errno = saved_errno;
143		goto fail;
144	}
145	setblocking(fd, 0);
146
147	return (fd);
148
149fail:
150	if (cause != NULL) {
151		xasprintf(cause, "error creating %s (%s)", socket_path,
152		    strerror(errno));
153	}
154	return (-1);
155}
156
157/* Tidy up every hour. */
158static void
159server_tidy_event(__unused int fd, __unused short events, __unused void *data)
160{
161    struct timeval	tv = { .tv_sec = 3600 };
162    uint64_t		t = get_timer();
163
164    format_tidy_jobs();
165
166    log_debug("%s: took %llu milliseconds", __func__,
167        (unsigned long long)(get_timer() - t));
168    evtimer_add(&server_ev_tidy, &tv);
169}
170
171/* Fork new server. */
172int
173server_start(struct tmuxproc *client, int flags, struct event_base *base,
174    int lockfd, char *lockfile)
175{
176	int		 fd;
177	sigset_t	 set, oldset;
178	struct client	*c = NULL;
179	char		*cause = NULL;
180	struct timeval	 tv = { .tv_sec = 3600 };
181
182	sigfillset(&set);
183	sigprocmask(SIG_BLOCK, &set, &oldset);
184
185	if (~flags & CLIENT_NOFORK) {
186		if (proc_fork_and_daemon(&fd) != 0) {
187			sigprocmask(SIG_SETMASK, &oldset, NULL);
188			return (fd);
189		}
190	}
191	proc_clear_signals(client, 0);
192	server_client_flags = flags;
193
194	if (event_reinit(base) != 0)
195		fatalx("event_reinit failed");
196	server_proc = proc_start("server");
197
198	proc_set_signals(server_proc, server_signal);
199	sigprocmask(SIG_SETMASK, &oldset, NULL);
200
201	if (log_get_level() > 1)
202		tty_create_log();
203	if (pledge("stdio rpath wpath cpath fattr unix getpw recvfd proc exec "
204	    "tty ps", NULL) != 0)
205		fatal("pledge failed");
206
207	input_key_build();
208	RB_INIT(&windows);
209	RB_INIT(&all_window_panes);
210	TAILQ_INIT(&clients);
211	RB_INIT(&sessions);
212	key_bindings_init();
213	TAILQ_INIT(&message_log);
214	gettimeofday(&start_time, NULL);
215
216	server_fd = server_create_socket(flags, &cause);
217	if (server_fd != -1)
218		server_update_socket();
219	if (~flags & CLIENT_NOFORK)
220		c = server_client_create(fd);
221	else
222		options_set_number(global_options, "exit-empty", 0);
223
224	if (lockfd >= 0) {
225		unlink(lockfile);
226		free(lockfile);
227		close(lockfd);
228	}
229
230	if (cause != NULL) {
231		if (c != NULL) {
232			c->exit_message = cause;
233			c->flags |= CLIENT_EXIT;
234		} else {
235			fprintf(stderr, "%s\n", cause);
236			exit(1);
237		}
238	}
239
240	evtimer_set(&server_ev_tidy, server_tidy_event, NULL);
241	evtimer_add(&server_ev_tidy, &tv);
242
243	server_acl_init();
244
245	server_add_accept(0);
246	proc_loop(server_proc, server_loop);
247
248	job_kill_all();
249	status_prompt_save_history();
250
251	exit(0);
252}
253
254/* Server loop callback. */
255static int
256server_loop(void)
257{
258	struct client	*c;
259	u_int		 items;
260
261	current_time = time(NULL);
262
263	do {
264		items = cmdq_next(NULL);
265		TAILQ_FOREACH(c, &clients, entry) {
266			if (c->flags & CLIENT_IDENTIFIED)
267				items += cmdq_next(c);
268		}
269	} while (items != 0);
270
271	server_client_loop();
272
273	if (!options_get_number(global_options, "exit-empty") && !server_exit)
274		return (0);
275
276	if (!options_get_number(global_options, "exit-unattached")) {
277		if (!RB_EMPTY(&sessions))
278			return (0);
279	}
280
281	TAILQ_FOREACH(c, &clients, entry) {
282		if (c->session != NULL)
283			return (0);
284	}
285
286	/*
287	 * No attached clients therefore want to exit - flush any waiting
288	 * clients but don't actually exit until they've gone.
289	 */
290	cmd_wait_for_flush();
291	if (!TAILQ_EMPTY(&clients))
292		return (0);
293
294	if (job_still_running())
295		return (0);
296
297	return (1);
298}
299
300/* Exit the server by killing all clients and windows. */
301static void
302server_send_exit(void)
303{
304	struct client	*c, *c1;
305	struct session	*s, *s1;
306
307	cmd_wait_for_flush();
308
309	TAILQ_FOREACH_SAFE(c, &clients, entry, c1) {
310		if (c->flags & CLIENT_SUSPENDED)
311			server_client_lost(c);
312		else {
313			c->flags |= CLIENT_EXIT;
314			c->exit_type = CLIENT_EXIT_SHUTDOWN;
315		}
316		c->session = NULL;
317	}
318
319	RB_FOREACH_SAFE(s, sessions, &sessions, s1)
320		session_destroy(s, 1, __func__);
321}
322
323/* Update socket execute permissions based on whether sessions are attached. */
324void
325server_update_socket(void)
326{
327	struct session	*s;
328	static int	 last = -1;
329	int		 n, mode;
330	struct stat      sb;
331
332	n = 0;
333	RB_FOREACH(s, sessions, &sessions) {
334		if (s->attached != 0) {
335			n++;
336			break;
337		}
338	}
339
340	if (n != last) {
341		last = n;
342
343		if (stat(socket_path, &sb) != 0)
344			return;
345		mode = sb.st_mode & ACCESSPERMS;
346		if (n != 0) {
347			if (mode & S_IRUSR)
348				mode |= S_IXUSR;
349			if (mode & S_IRGRP)
350				mode |= S_IXGRP;
351			if (mode & S_IROTH)
352				mode |= S_IXOTH;
353		} else
354			mode &= ~(S_IXUSR|S_IXGRP|S_IXOTH);
355		chmod(socket_path, mode);
356	}
357}
358
359/* Callback for server socket. */
360static void
361server_accept(int fd, short events, __unused void *data)
362{
363	struct sockaddr_storage	 sa;
364	socklen_t		 slen = sizeof sa;
365	int			 newfd;
366	struct client		*c;
367
368	server_add_accept(0);
369	if (!(events & EV_READ))
370		return;
371
372	newfd = accept(fd, (struct sockaddr *) &sa, &slen);
373	if (newfd == -1) {
374		if (errno == EAGAIN || errno == EINTR || errno == ECONNABORTED)
375			return;
376		if (errno == ENFILE || errno == EMFILE) {
377			/* Delete and don't try again for 1 second. */
378			server_add_accept(1);
379			return;
380		}
381		fatal("accept failed");
382	}
383
384	if (server_exit) {
385		close(newfd);
386		return;
387	}
388	c = server_client_create(newfd);
389	if (!server_acl_join(c)) {
390		c->exit_message = xstrdup("access not allowed");
391		c->flags |= CLIENT_EXIT;
392	}
393}
394
395/*
396 * Add accept event. If timeout is nonzero, add as a timeout instead of a read
397 * event - used to backoff when running out of file descriptors.
398 */
399void
400server_add_accept(int timeout)
401{
402	struct timeval tv = { timeout, 0 };
403
404	if (server_fd == -1)
405		return;
406
407	if (event_initialized(&server_ev_accept))
408		event_del(&server_ev_accept);
409
410	if (timeout == 0) {
411		event_set(&server_ev_accept, server_fd, EV_READ, server_accept,
412		    NULL);
413		event_add(&server_ev_accept, NULL);
414	} else {
415		event_set(&server_ev_accept, server_fd, EV_TIMEOUT,
416		    server_accept, NULL);
417		event_add(&server_ev_accept, &tv);
418	}
419}
420
421/* Signal handler. */
422static void
423server_signal(int sig)
424{
425	int	fd;
426
427	log_debug("%s: %s", __func__, strsignal(sig));
428	switch (sig) {
429	case SIGINT:
430	case SIGTERM:
431		server_exit = 1;
432		server_send_exit();
433		break;
434	case SIGCHLD:
435		server_child_signal();
436		break;
437	case SIGUSR1:
438		event_del(&server_ev_accept);
439		fd = server_create_socket(server_client_flags, NULL);
440		if (fd != -1) {
441			close(server_fd);
442			server_fd = fd;
443			server_update_socket();
444		}
445		server_add_accept(0);
446		break;
447	case SIGUSR2:
448		proc_toggle_log(server_proc);
449		break;
450	}
451}
452
453/* Handle SIGCHLD. */
454static void
455server_child_signal(void)
456{
457	int	 status;
458	pid_t	 pid;
459
460	for (;;) {
461		switch (pid = waitpid(WAIT_ANY, &status, WNOHANG|WUNTRACED)) {
462		case -1:
463			if (errno == ECHILD)
464				return;
465			fatal("waitpid failed");
466		case 0:
467			return;
468		}
469		if (WIFSTOPPED(status))
470			server_child_stopped(pid, status);
471		else if (WIFEXITED(status) || WIFSIGNALED(status))
472			server_child_exited(pid, status);
473	}
474}
475
476/* Handle exited children. */
477static void
478server_child_exited(pid_t pid, int status)
479{
480	struct window		*w, *w1;
481	struct window_pane	*wp;
482
483	RB_FOREACH_SAFE(w, windows, &windows, w1) {
484		TAILQ_FOREACH(wp, &w->panes, entry) {
485			if (wp->pid == pid) {
486				wp->status = status;
487				wp->flags |= PANE_STATUSREADY;
488
489				log_debug("%%%u exited", wp->id);
490				wp->flags |= PANE_EXITED;
491
492				if (window_pane_destroy_ready(wp))
493					server_destroy_pane(wp, 1);
494				break;
495			}
496		}
497	}
498	job_check_died(pid, status);
499}
500
501/* Handle stopped children. */
502static void
503server_child_stopped(pid_t pid, int status)
504{
505	struct window		*w;
506	struct window_pane	*wp;
507
508	if (WSTOPSIG(status) == SIGTTIN || WSTOPSIG(status) == SIGTTOU)
509		return;
510
511	RB_FOREACH(w, windows, &windows) {
512		TAILQ_FOREACH(wp, &w->panes, entry) {
513			if (wp->pid == pid) {
514				if (killpg(pid, SIGCONT) != 0)
515					kill(pid, SIGCONT);
516			}
517		}
518	}
519	job_check_died(pid, status);
520}
521
522/* Add to message log. */
523void
524server_add_message(const char *fmt, ...)
525{
526	struct message_entry	*msg, *msg1;
527	char			*s;
528	va_list			 ap;
529	u_int			 limit;
530
531	va_start(ap, fmt);
532	xvasprintf(&s, fmt, ap);
533	va_end(ap);
534
535	log_debug("message: %s", s);
536
537	msg = xcalloc(1, sizeof *msg);
538	gettimeofday(&msg->msg_time, NULL);
539	msg->msg_num = message_next++;
540	msg->msg = s;
541	TAILQ_INSERT_TAIL(&message_log, msg, entry);
542
543	limit = options_get_number(global_options, "message-limit");
544	TAILQ_FOREACH_SAFE(msg, &message_log, entry, msg1) {
545		if (msg->msg_num + limit >= message_next)
546			break;
547		free(msg->msg);
548		TAILQ_REMOVE(&message_log, msg, entry);
549		free(msg);
550	}
551}
552