/* $OpenBSD: server.c,v 1.209 2025/08/14 06:49:53 nicm Exp $ */

/*
 * Copyright (c) 2007 Nicholas Marriott <nicholas.marriott@gmail.com>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF MIND, USE, DATA OR PROFITS, WHETHER
 * IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
 * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <sys/types.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/un.h>
#include <sys/wait.h>

#include <errno.h>
#include <event.h>
#include <fcntl.h>
#include <paths.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <termios.h>
#include <time.h>
#include <unistd.h>

#include "tmux.h"

/*
 * Main server functions.
 */

struct clients           clients;

struct tmuxproc         *server_proc;
static int               server_fd = -1;
static uint64_t          server_client_flags;
static int               server_exit;
static struct event      server_ev_accept;
static struct event      server_ev_tidy;

struct cmd_find_state    marked_pane;

static u_int             message_next;
struct message_list      message_log;

time_t                   current_time;

static int      server_loop(void);
static void     server_send_exit(void);
static void     server_accept(int, short, void *);
static void     server_signal(int);
static void     server_child_signal(void);
static void     server_child_exited(pid_t, int);
static void     server_child_stopped(pid_t, int);

/* Set marked pane. */
void
server_set_marked(struct session *s, struct winlink *wl, struct window_pane *wp)
{
        cmd_find_clear_state(&marked_pane, 0);
        marked_pane.s = s;
        marked_pane.wl = wl;
        if (wl != NULL)
                marked_pane.w = wl->window;
        marked_pane.wp = wp;
}

/* Clear marked pane. */
void
server_clear_marked(void)
{
        cmd_find_clear_state(&marked_pane, 0);
}

/* Is this the marked pane? */
int
server_is_marked(struct session *s, struct winlink *wl, struct window_pane *wp)
{
        if (s == NULL || wl == NULL || wp == NULL)
                return (0);
        if (marked_pane.s != s || marked_pane.wl != wl)
                return (0);
        if (marked_pane.wp != wp)
                return (0);
        return (server_check_marked());
}

/* Check if the marked pane is still valid. */
int
server_check_marked(void)
{
        return (cmd_find_valid_state(&marked_pane));
}

/* Create server socket. */
int
server_create_socket(uint64_t flags, char **cause)
{
        struct sockaddr_un      sa;
        size_t                  size;
        mode_t                  mask;
        int                     fd, saved_errno;

        memset(&sa, 0, sizeof sa);
        sa.sun_family = AF_UNIX;
        size = strlcpy(sa.sun_path, socket_path, sizeof sa.sun_path);
        if (size >= sizeof sa.sun_path) {
                errno = ENAMETOOLONG;
                goto fail;
        }
        unlink(sa.sun_path);

        if ((fd = socket(AF_UNIX, SOCK_STREAM, 0)) == -1)
                goto fail;

        if (flags & CLIENT_DEFAULTSOCKET)
                mask = umask(S_IXUSR|S_IXGRP|S_IRWXO);
        else
                mask = umask(S_IXUSR|S_IRWXG|S_IRWXO);
        if (bind(fd, (struct sockaddr *)&sa, sizeof sa) == -1) {
                saved_errno = errno;
                close(fd);
                errno = saved_errno;
                goto fail;
        }
        umask(mask);

        if (listen(fd, 128) == -1) {
                saved_errno = errno;
                close(fd);
                errno = saved_errno;
                goto fail;
        }
        setblocking(fd, 0);

        return (fd);

fail:
        if (cause != NULL) {
                xasprintf(cause, "error creating %s (%s)", socket_path,
                    strerror(errno));
        }
        return (-1);
}

/* Tidy up every hour. */
static void
server_tidy_event(__unused int fd, __unused short events, __unused void *data)
{
    struct timeval      tv = { .tv_sec = 3600 };
    uint64_t            t = get_timer();

    format_tidy_jobs();

    log_debug("%s: took %llu milliseconds", __func__,
        (unsigned long long)(get_timer() - t));
    evtimer_add(&server_ev_tidy, &tv);
}

/* Fork new server. */
int
server_start(struct tmuxproc *client, uint64_t flags, struct event_base *base,
    int lockfd, char *lockfile)
{
        int              fd;
        sigset_t         set, oldset;
        struct client   *c = NULL;
        char            *cause = NULL;
        struct timeval   tv = { .tv_sec = 3600 };

        sigfillset(&set);
        sigprocmask(SIG_BLOCK, &set, &oldset);

        if (~flags & CLIENT_NOFORK) {
                if (proc_fork_and_daemon(&fd) != 0) {
                        sigprocmask(SIG_SETMASK, &oldset, NULL);
                        return (fd);
                }
        }
        proc_clear_signals(client, 0);
        server_client_flags = flags;

        if (event_reinit(base) != 0)
                fatalx("event_reinit failed");
        server_proc = proc_start("server");

        proc_set_signals(server_proc, server_signal);
        sigprocmask(SIG_SETMASK, &oldset, NULL);

        if (log_get_level() > 1)
                tty_create_log();
        if (pledge("stdio rpath wpath cpath fattr unix getpw recvfd proc exec "
            "tty ps", NULL) != 0)
                fatal("pledge failed");

        input_key_build();
        utf8_update_width_cache();
        RB_INIT(&windows);
        RB_INIT(&all_window_panes);
        TAILQ_INIT(&clients);
        RB_INIT(&sessions);
        key_bindings_init();
        TAILQ_INIT(&message_log);
        gettimeofday(&start_time, NULL);

        server_fd = server_create_socket(flags, &cause);
        if (server_fd != -1)
                server_update_socket();
        if (~flags & CLIENT_NOFORK)
                c = server_client_create(fd);
        else
                options_set_number(global_options, "exit-empty", 0);

        if (lockfd >= 0) {
                unlink(lockfile);
                free(lockfile);
                close(lockfd);
        }

        if (cause != NULL) {
                if (c != NULL) {
                        c->exit_message = cause;
                        c->flags |= CLIENT_EXIT;
                } else {
                        fprintf(stderr, "%s\n", cause);
                        exit(1);
                }
        }

        evtimer_set(&server_ev_tidy, server_tidy_event, NULL);
        evtimer_add(&server_ev_tidy, &tv);

        server_acl_init();

        server_add_accept(0);
        proc_loop(server_proc, server_loop);

        job_kill_all();
        status_prompt_save_history();

        exit(0);
}

/* Server loop callback. */
static int
server_loop(void)
{
        struct client   *c;
        u_int            items;

        current_time = time(NULL);

        do {
                items = cmdq_next(NULL);
                TAILQ_FOREACH(c, &clients, entry) {
                        if (c->flags & CLIENT_IDENTIFIED)
                                items += cmdq_next(c);
                }
        } while (items != 0);

        server_client_loop();

        if (!options_get_number(global_options, "exit-empty") && !server_exit)
                return (0);

        if (!options_get_number(global_options, "exit-unattached")) {
                if (!RB_EMPTY(&sessions))
                        return (0);
        }

        TAILQ_FOREACH(c, &clients, entry) {
                if (c->session != NULL)
                        return (0);
        }

        /*
         * No attached clients therefore want to exit - flush any waiting
         * clients but don't actually exit until they've gone.
         */
        cmd_wait_for_flush();
        if (!TAILQ_EMPTY(&clients))
                return (0);

        if (job_still_running())
                return (0);

        return (1);
}

/* Exit the server by killing all clients and windows. */
static void
server_send_exit(void)
{
        struct client   *c, *c1;
        struct session  *s, *s1;

        cmd_wait_for_flush();

        TAILQ_FOREACH_SAFE(c, &clients, entry, c1) {
                if (c->flags & CLIENT_SUSPENDED)
                        server_client_lost(c);
                else {
                        c->flags |= CLIENT_EXIT;
                        c->exit_type = CLIENT_EXIT_SHUTDOWN;
                }
                c->session = NULL;
        }

        RB_FOREACH_SAFE(s, sessions, &sessions, s1)
                session_destroy(s, 1, __func__);
}

/* Update socket execute permissions based on whether sessions are attached. */
void
server_update_socket(void)
{
        struct session  *s;
        static int       last = -1;
        int              n, mode;
        struct stat      sb;

        n = 0;
        RB_FOREACH(s, sessions, &sessions) {
                if (s->attached != 0) {
                        n++;
                        break;
                }
        }

        if (n != last) {
                last = n;

                if (stat(socket_path, &sb) != 0)
                        return;
                mode = sb.st_mode & ACCESSPERMS;
                if (n != 0) {
                        if (mode & S_IRUSR)
                                mode |= S_IXUSR;
                        if (mode & S_IRGRP)
                                mode |= S_IXGRP;
                        if (mode & S_IROTH)
                                mode |= S_IXOTH;
                } else
                        mode &= ~(S_IXUSR|S_IXGRP|S_IXOTH);
                chmod(socket_path, mode);
        }
}

/* Callback for server socket. */
static void
server_accept(int fd, short events, __unused void *data)
{
        struct sockaddr_storage  sa;
        socklen_t                slen = sizeof sa;
        int                      newfd;
        struct client           *c;

        server_add_accept(0);
        if (!(events & EV_READ))
                return;

        newfd = accept(fd, (struct sockaddr *) &sa, &slen);
        if (newfd == -1) {
                if (errno == EAGAIN || errno == EINTR || errno == ECONNABORTED)
                        return;
                if (errno == ENFILE || errno == EMFILE) {
                        /* Delete and don't try again for 1 second. */
                        server_add_accept(1);
                        return;
                }
                fatal("accept failed");
        }

        if (server_exit) {
                close(newfd);
                return;
        }
        c = server_client_create(newfd);
        if (!server_acl_join(c)) {
                c->exit_message = xstrdup("access not allowed");
                c->flags |= CLIENT_EXIT;
        }
}

/*
 * Add accept event. If timeout is nonzero, add as a timeout instead of a read
 * event - used to backoff when running out of file descriptors.
 */
void
server_add_accept(int timeout)
{
        struct timeval tv = { timeout, 0 };

        if (server_fd == -1)
                return;

        if (event_initialized(&server_ev_accept))
                event_del(&server_ev_accept);

        if (timeout == 0) {
                event_set(&server_ev_accept, server_fd, EV_READ, server_accept,
                    NULL);
                event_add(&server_ev_accept, NULL);
        } else {
                event_set(&server_ev_accept, server_fd, EV_TIMEOUT,
                    server_accept, NULL);
                event_add(&server_ev_accept, &tv);
        }
}

/* Signal handler. */
static void
server_signal(int sig)
{
        int     fd;

        log_debug("%s: %s", __func__, strsignal(sig));
        switch (sig) {
        case SIGINT:
        case SIGTERM:
                server_exit = 1;
                server_send_exit();
                break;
        case SIGCHLD:
                server_child_signal();
                break;
        case SIGUSR1:
                event_del(&server_ev_accept);
                fd = server_create_socket(server_client_flags, NULL);
                if (fd != -1) {
                        close(server_fd);
                        server_fd = fd;
                        server_update_socket();
                }
                server_add_accept(0);
                break;
        case SIGUSR2:
                proc_toggle_log(server_proc);
                break;
        }
}

/* Handle SIGCHLD. */
static void
server_child_signal(void)
{
        int      status;
        pid_t    pid;

        for (;;) {
                switch (pid = waitpid(WAIT_ANY, &status, WNOHANG|WUNTRACED)) {
                case -1:
                        if (errno == ECHILD)
                                return;
                        fatal("waitpid failed");
                case 0:
                        return;
                }
                if (WIFSTOPPED(status))
                        server_child_stopped(pid, status);
                else if (WIFEXITED(status) || WIFSIGNALED(status))
                        server_child_exited(pid, status);
        }
}

/* Handle exited children. */
static void
server_child_exited(pid_t pid, int status)
{
        struct window           *w, *w1;
        struct window_pane      *wp;

        RB_FOREACH_SAFE(w, windows, &windows, w1) {
                TAILQ_FOREACH(wp, &w->panes, entry) {
                        if (wp->pid == pid) {
                                wp->status = status;
                                wp->flags |= PANE_STATUSREADY;

                                log_debug("%%%u exited", wp->id);
                                wp->flags |= PANE_EXITED;

                                if (window_pane_destroy_ready(wp))
                                        server_destroy_pane(wp, 1);
                                break;
                        }
                }
        }
        job_check_died(pid, status);
}

/* Handle stopped children. */
static void
server_child_stopped(pid_t pid, int status)
{
        struct window           *w;
        struct window_pane      *wp;

        if (WSTOPSIG(status) == SIGTTIN || WSTOPSIG(status) == SIGTTOU)
                return;

        RB_FOREACH(w, windows, &windows) {
                TAILQ_FOREACH(wp, &w->panes, entry) {
                        if (wp->pid == pid) {
                                if (killpg(pid, SIGCONT) != 0)
                                        kill(pid, SIGCONT);
                        }
                }
        }
        job_check_died(pid, status);
}

/* Add to message log. */
void
server_add_message(const char *fmt, ...)
{
        struct message_entry    *msg, *msg1;
        char                    *s;
        va_list                  ap;
        u_int                    limit;

        va_start(ap, fmt);
        xvasprintf(&s, fmt, ap);
        va_end(ap);

        log_debug("message: %s", s);

        msg = xcalloc(1, sizeof *msg);
        gettimeofday(&msg->msg_time, NULL);
        msg->msg_num = message_next++;
        msg->msg = s;
        TAILQ_INSERT_TAIL(&message_log, msg, entry);

        limit = options_get_number(global_options, "message-limit");
        TAILQ_FOREACH_SAFE(msg, &message_log, entry, msg1) {
                if (msg->msg_num + limit >= message_next)
                        break;
                free(msg->msg);
                TAILQ_REMOVE(&message_log, msg, entry);
                free(msg);
        }
}