Merge pull request #912 from chiragshah6/mdev

[mirror_frr.git] / watchfrr / watchfrr.c

/*
 * Monitor status of frr daemons and restart if necessary.
 *
 * Copyright (C) 2004  Andrew J. Schorr
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; see the file COPYING; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include <zebra.h>
#include <thread.h>
#include <log.h>
#include <network.h>
#include <sigevent.h>
#include <lib/version.h>
#include "command.h"
#include "memory_vty.h"
#include "libfrr.h"

#include <getopt.h>
#include <sys/un.h>
#include <sys/wait.h>
#include <memory.h>
#include <systemd.h>

#include "watchfrr.h"

#ifndef MIN
#define MIN(X,Y) (((X) <= (Y)) ? (X) : (Y))
#endif

/* Macros to help randomize timers. */
#define JITTER(X) ((random() % ((X)+1))-((X)/2))
#define FUZZY(X) ((X)+JITTER((X)/20))

#define DEFAULT_PERIOD          5
#define DEFAULT_TIMEOUT         10
#define DEFAULT_RESTART_TIMEOUT 20
#define DEFAULT_LOGLEVEL        LOG_INFO
#define DEFAULT_MIN_RESTART     60
#define DEFAULT_MAX_RESTART     600
#ifdef PATH_WATCHFRR_PID
#define DEFAULT_PIDFILE         PATH_WATCHFRR_PID
#else
#define DEFAULT_PIDFILE         STATEDIR "/watchfrr.pid"
#endif
#ifdef DAEMON_VTY_DIR
#define VTYDIR                  DAEMON_VTY_DIR
#else
#define VTYDIR                  STATEDIR
#endif

#define PING_TOKEN      "PING"

/* Needs to be global, referenced somewhere inside libfrr. */
struct thread_master *master;

typedef enum {
        MODE_MONITOR = 0,
        MODE_GLOBAL_RESTART,
        MODE_SEPARATE_RESTART,
        MODE_PHASED_ZEBRA_RESTART,
        MODE_PHASED_ALL_RESTART
} watch_mode_t;

static const char *mode_str[] = {
        "monitor",
        "global restart",
        "individual daemon restart",
        "phased zebra restart",
        "phased global restart for any failure",
};

typedef enum {
        PHASE_NONE = 0,
        PHASE_STOPS_PENDING,
        PHASE_WAITING_DOWN,
        PHASE_ZEBRA_RESTART_PENDING,
        PHASE_WAITING_ZEBRA_UP
} restart_phase_t;

static const char *phase_str[] = {
        "None",
        "Stop jobs running",
        "Waiting for other daemons to come down",
        "Zebra restart job running",
        "Waiting for zebra to come up",
        "Start jobs running",
};

#define PHASE_TIMEOUT (3*gs.restart_timeout)

struct restart_info {
        const char *name;
        const char *what;
        pid_t pid;
        struct timeval time;
        long interval;
        struct thread *t_kill;
        int kills;
};

static struct global_state {
        watch_mode_t mode;
        restart_phase_t phase;
        struct thread *t_phase_hanging;
        const char *vtydir;
        long period;
        long timeout;
        long restart_timeout;
        long min_restart_interval;
        long max_restart_interval;
        int do_ping;
        struct daemon *daemons;
        const char *restart_command;
        const char *start_command;
        const char *stop_command;
        struct restart_info restart;
        int unresponsive_restart;
        int loglevel;
        struct daemon *special; /* points to zebra when doing phased restart */
        int numdaemons;
        int numpids;
        int numdown; /* # of daemons that are not UP or UNRESPONSIVE */
} gs = {
        .mode = MODE_MONITOR,
        .phase = PHASE_NONE,
        .vtydir = VTYDIR,
        .period = 1000 * DEFAULT_PERIOD,
        .timeout = DEFAULT_TIMEOUT,
        .restart_timeout = DEFAULT_RESTART_TIMEOUT,
        .loglevel = DEFAULT_LOGLEVEL,
        .min_restart_interval = DEFAULT_MIN_RESTART,
        .max_restart_interval = DEFAULT_MAX_RESTART,
        .do_ping = 1,
};

typedef enum {
        DAEMON_INIT,
        DAEMON_DOWN,
        DAEMON_CONNECTING,
        DAEMON_UP,
        DAEMON_UNRESPONSIVE
} daemon_state_t;

#define IS_UP(DMN)                                                             \
        (((DMN)->state == DAEMON_UP) || ((DMN)->state == DAEMON_UNRESPONSIVE))

static const char *state_str[] = {
        "Init", "Down", "Connecting", "Up", "Unresponsive",
};

struct daemon {
        const char *name;
        daemon_state_t state;
        int fd;
        struct timeval echo_sent;
        u_int connect_tries;
        struct thread *t_wakeup;
        struct thread *t_read;
        struct thread *t_write;
        struct daemon *next;
        struct restart_info restart;
};

#define OPTION_MINRESTART 2000
#define OPTION_MAXRESTART 2001

static const struct option longopts[] = {
        {"daemon", no_argument, NULL, 'd'},
        {"statedir", required_argument, NULL, 'S'},
        {"no-echo", no_argument, NULL, 'e'},
        {"loglevel", required_argument, NULL, 'l'},
        {"interval", required_argument, NULL, 'i'},
        {"timeout", required_argument, NULL, 't'},
        {"restart-timeout", required_argument, NULL, 'T'},
        {"restart", required_argument, NULL, 'r'},
        {"start-command", required_argument, NULL, 's'},
        {"kill-command", required_argument, NULL, 'k'},
        {"restart-all", required_argument, NULL, 'R'},
        {"all-restart", no_argument, NULL, 'a'},
        {"always-all-restart", no_argument, NULL, 'A'},
        {"unresponsive-restart", no_argument, NULL, 'z'},
        {"min-restart-interval", required_argument, NULL, OPTION_MINRESTART},
        {"max-restart-interval", required_argument, NULL, OPTION_MAXRESTART},
        {"pid-file", required_argument, NULL, 'p'},
        {"blank-string", required_argument, NULL, 'b'},
        {"help", no_argument, NULL, 'h'},
        {"version", no_argument, NULL, 'v'},
        {NULL, 0, NULL, 0}};

static int try_connect(struct daemon *dmn);
static int wakeup_send_echo(struct thread *t_wakeup);
static void try_restart(struct daemon *dmn);
static void phase_check(void);

static const char *progname;
static void printhelp(FILE *target)
{
        fprintf(target,
                "Usage : %s [OPTION...] <daemon name> ...\n\n\
Watchdog program to monitor status of frr daemons and try to restart\n\
them if they are down or unresponsive.  It determines whether a daemon is\n\
up based on whether it can connect to the daemon's vty unix stream socket.\n\
It then repeatedly sends echo commands over that socket to determine whether\n\
the daemon is responsive.  If the daemon crashes, we will receive an EOF\n\
on the socket connection and know immediately that the daemon is down.\n\n\
The daemons to be monitored should be listed on the command line.\n\n\
This program can run in one of 5 modes:\n\n\
0. Mode: %s.\n\
  Just monitor and report on status changes.  Example:\n\
    %s -d zebra ospfd bgpd\n\n\
1. Mode: %s.\n\
  Whenever any daemon hangs or crashes, use the given command to restart\n\
  them all.  Example:\n\
    %s -dz \\\n\
      -R '/sbin/service zebra restart; /sbin/service ospfd restart' \\\n\
      zebra ospfd\n\n\
2. Mode: %s.\n\
  When any single daemon hangs or crashes, restart only the daemon that's\n\
  in trouble using the supplied restart command.  Example:\n\
    %s -dz -r '/sbin/service %%s restart' zebra ospfd bgpd\n\n\
3. Mode: %s.\n\
  The same as the previous mode, except that there is special treatment when\n\
  the zebra daemon is in trouble.  In that case, a phased restart approach\n\
  is used: 1. stop all other daemons; 2. restart zebra; 3. start the other\n\
  daemons.  Example:\n\
    %s -adz -r '/sbin/service %%s restart' \\\n\
      -s '/sbin/service %%s start' \\\n\
      -k '/sbin/service %%s stop' zebra ospfd bgpd\n\n\
4. Mode: %s.\n\
  This is the same as the previous mode, except that the phased restart\n\
  procedure is used whenever any of the daemons hangs or crashes.  Example:\n\
    %s -Adz -r '/sbin/service %%s restart' \\\n\
      -s '/sbin/service %%s start' \\\n\
      -k '/sbin/service %%s stop' zebra ospfd bgpd\n\n\
As of this writing, it is believed that mode 2 [%s]\n\
is not safe, and mode 3 [%s] may not be safe with some of the\n\
routing daemons.\n\n\
In order to avoid attempting to restart the daemons in a fast loop,\n\
the -m and -M options allow you to control the minimum delay between\n\
restart commands.  The minimum restart delay is recalculated each time\n\
a restart is attempted: if the time since the last restart attempt exceeds\n\
twice the -M value, then the restart delay is set to the -m value.\n\
Otherwise, the interval is doubled (but capped at the -M value).\n\n",
                progname, mode_str[0], progname, mode_str[1], progname,
                mode_str[2], progname, mode_str[3], progname, mode_str[4],
                progname, mode_str[2], mode_str[3]);

        fprintf(target,
                "Options:\n\
-d, --daemon    Run in daemon mode.  In this mode, error messages are sent\n\
                to syslog instead of stdout.\n\
-S, --statedir  Set the vty socket directory (default is %s)\n\
-e, --no-echo   Do not ping the daemons to test responsiveness (this\n\
                option is necessary if the daemons do not support the\n\
                echo command)\n\
-l, --loglevel  Set the logging level (default is %d).\n\
                The value should range from %d (LOG_EMERG) to %d (LOG_DEBUG),\n\
                but it can be set higher than %d if extra-verbose debugging\n\
                messages are desired.\n\
    --min-restart-interval\n\
                Set the minimum seconds to wait between invocations of daemon\n\
                restart commands (default is %d).\n\
    --max-restart-interval\n\
                Set the maximum seconds to wait between invocations of daemon\n\
                restart commands (default is %d).\n\
-i, --interval  Set the status polling interval in seconds (default is %d)\n\
-t, --timeout   Set the unresponsiveness timeout in seconds (default is %d)\n\
-T, --restart-timeout\n\
                Set the restart (kill) timeout in seconds (default is %d).\n\
                If any background jobs are still running after this much\n\
                time has elapsed, they will be killed.\n\
-r, --restart   Supply a Bourne shell command to use to restart a single\n\
                daemon.  The command string should include '%%s' where the\n\
                name of the daemon should be substituted.\n\
                Note that -r and -R are incompatible.\n\
-s, --start-command\n\
                Supply a Bourne shell to command to use to start a single\n\
                daemon.  The command string should include '%%s' where the\n\
                name of the daemon should be substituted.\n\
-k, --kill-command\n\
                Supply a Bourne shell to command to use to stop a single\n\
                daemon.  The command string should include '%%s' where the\n\
                name of the daemon should be substituted.\n\
-R, --restart-all\n\
                When one or more daemons is down, try to restart everything\n\
                using the Bourne shell command supplied as the argument.\n\
                Note that -r and -R are incompatible.\n\
-z, --unresponsive-restart\n\
                When a daemon is unresponsive, treat it as being down for\n\
                restart purposes.\n\
-a, --all-restart\n\
                When zebra hangs or crashes, restart all daemons using\n\
                this phased approach: 1. stop all other daemons; 2. restart\n\
                zebra; 3. start other daemons.  Requires -r, -s, and -k.\n\
-A, --always-all-restart\n\
                When any daemon (not just zebra) hangs or crashes, use the\n\
                same phased restart mechanism described above for -a.\n\
                Requires -r, -s, and -k.\n\
-p, --pid-file  Set process identifier file name\n\
                (default is %s).\n\
-b, --blank-string\n\
                When the supplied argument string is found in any of the\n\
                various shell command arguments (-r, -s, -k, or -R), replace\n\
                it with a space.  This is an ugly hack to circumvent problems\n\
                passing command-line arguments with embedded spaces.\n\
-v, --version   Print program version\n\
-h, --help      Display this help and exit\n",
                VTYDIR, DEFAULT_LOGLEVEL, LOG_EMERG, LOG_DEBUG, LOG_DEBUG,
                DEFAULT_MIN_RESTART, DEFAULT_MAX_RESTART, DEFAULT_PERIOD,
                DEFAULT_TIMEOUT, DEFAULT_RESTART_TIMEOUT, DEFAULT_PIDFILE);
}

static pid_t run_background(char *shell_cmd)
{
        pid_t child;

        switch (child = fork()) {
        case -1:
                zlog_err("fork failed, cannot run command [%s]: %s", shell_cmd,
                         safe_strerror(errno));
                return -1;
        case 0:
                /* Child process. */
                /* Use separate process group so child processes can be killed
                 * easily. */
                if (setpgid(0, 0) < 0)
                        zlog_warn("warning: setpgid(0,0) failed: %s",
                                  safe_strerror(errno));
                {
                        char shell[] = "sh";
                        char dashc[] = "-c";
                        char *const argv[4] = {shell, dashc, shell_cmd, NULL};
                        execv("/bin/sh", argv);
                        zlog_err("execv(/bin/sh -c '%s') failed: %s", shell_cmd,
                                 safe_strerror(errno));
                        _exit(127);
                }
        default:
                /* Parent process: we will reap the child later. */
                zlog_err("Forked background command [pid %d]: %s", (int)child,
                         shell_cmd);
                return child;
        }
}

static struct timeval *time_elapsed(struct timeval *result,
                                    const struct timeval *start_time)
{
        gettimeofday(result, NULL);
        result->tv_sec -= start_time->tv_sec;
        result->tv_usec -= start_time->tv_usec;
        while (result->tv_usec < 0) {
                result->tv_usec += 1000000L;
                result->tv_sec--;
        }
        return result;
}

static int restart_kill(struct thread *t_kill)
{
        struct restart_info *restart = THREAD_ARG(t_kill);
        struct timeval delay;

        time_elapsed(&delay, &restart->time);
        zlog_warn(
                "Warning: %s %s child process %d still running after "
                "%ld seconds, sending signal %d",
                restart->what, restart->name, (int)restart->pid,
                (long)delay.tv_sec, (restart->kills ? SIGKILL : SIGTERM));
        kill(-restart->pid, (restart->kills ? SIGKILL : SIGTERM));
        restart->kills++;
        restart->t_kill = NULL;
        thread_add_timer(master, restart_kill, restart, gs.restart_timeout,
                         &restart->t_kill);
        return 0;
}

static struct restart_info *find_child(pid_t child)
{
        if (gs.mode == MODE_GLOBAL_RESTART) {
                if (gs.restart.pid == child)
                        return &gs.restart;
        } else {
                struct daemon *dmn;
                for (dmn = gs.daemons; dmn; dmn = dmn->next) {
                        if (dmn->restart.pid == child)
                                return &dmn->restart;
                }
        }
        return NULL;
}

static void sigchild(void)
{
        pid_t child;
        int status;
        const char *name;
        const char *what;
        struct restart_info *restart;

        switch (child = waitpid(-1, &status, WNOHANG)) {
        case -1:
                zlog_err("waitpid failed: %s", safe_strerror(errno));
                return;
        case 0:
                zlog_warn("SIGCHLD received, but waitpid did not reap a child");
                return;
        }

        if (child == integrated_write_pid) {
                integrated_write_sigchld(status);
                return;
        }

        if ((restart = find_child(child)) != NULL) {
                name = restart->name;
                what = restart->what;
                restart->pid = 0;
                gs.numpids--;
                thread_cancel(restart->t_kill);
                restart->t_kill = NULL;
                /* Update restart time to reflect the time the command
                 * completed. */
                gettimeofday(&restart->time, NULL);
        } else {
                zlog_err(
                        "waitpid returned status for an unknown child process %d",
                        (int)child);
                name = "(unknown)";
                what = "background";
        }
        if (WIFSTOPPED(status))
                zlog_warn("warning: %s %s process %d is stopped", what, name,
                          (int)child);
        else if (WIFSIGNALED(status))
                zlog_warn("%s %s process %d terminated due to signal %d", what,
                          name, (int)child, WTERMSIG(status));
        else if (WIFEXITED(status)) {
                if (WEXITSTATUS(status) != 0)
                        zlog_warn(
                                "%s %s process %d exited with non-zero status %d",
                                what, name, (int)child, WEXITSTATUS(status));
                else
                        zlog_debug("%s %s process %d exited normally", what,
                                   name, (int)child);
        } else
                zlog_err("cannot interpret %s %s process %d wait status 0x%x",
                         what, name, (int)child, status);
        phase_check();
}

static int run_job(struct restart_info *restart, const char *cmdtype,
                   const char *command, int force, int update_interval)
{
        struct timeval delay;

        if (gs.loglevel > LOG_DEBUG + 1)
                zlog_debug("attempting to %s %s", cmdtype, restart->name);

        if (restart->pid) {
                if (gs.loglevel > LOG_DEBUG + 1)
                        zlog_debug(
                                "cannot %s %s, previous pid %d still running",
                                cmdtype, restart->name, (int)restart->pid);
                return -1;
        }

        /* Note: time_elapsed test must come before the force test, since we
           need
           to make sure that delay is initialized for use below in updating the
           restart interval. */
        if ((time_elapsed(&delay, &restart->time)->tv_sec < restart->interval)
            && !force) {
                if (gs.loglevel > LOG_DEBUG + 1)
                        zlog_debug(
                                "postponing %s %s: "
                                "elapsed time %ld < retry interval %ld",
                                cmdtype, restart->name, (long)delay.tv_sec,
                                restart->interval);
                return -1;
        }

        gettimeofday(&restart->time, NULL);
        restart->kills = 0;
        {
                char cmd[strlen(command) + strlen(restart->name) + 1];
                snprintf(cmd, sizeof(cmd), command, restart->name);
                if ((restart->pid = run_background(cmd)) > 0) {
                        restart->t_kill = NULL;
                        thread_add_timer(master, restart_kill, restart,
                                         gs.restart_timeout, &restart->t_kill);
                        restart->what = cmdtype;
                        gs.numpids++;
                } else
                        restart->pid = 0;
        }

        /* Calculate the new restart interval. */
        if (update_interval) {
                if (delay.tv_sec > 2 * gs.max_restart_interval)
                        restart->interval = gs.min_restart_interval;
                else if ((restart->interval *= 2) > gs.max_restart_interval)
                        restart->interval = gs.max_restart_interval;
                if (gs.loglevel > LOG_DEBUG + 1)
                        zlog_debug("restart %s interval is now %ld",
                                   restart->name, restart->interval);
        }
        return restart->pid;
}

#define SET_READ_HANDLER(DMN)                                                  \
        do {                                                                   \
                (DMN)->t_read = NULL;                                          \
                thread_add_read(master, handle_read, (DMN), (DMN)->fd,         \
                                &(DMN)->t_read);                               \
        } while (0);

#define SET_WAKEUP_DOWN(DMN)                                                   \
        do {                                                                   \
                (DMN)->t_wakeup = NULL;                                        \
                thread_add_timer_msec(master, wakeup_down, (DMN),              \
                                      FUZZY(gs.period), &(DMN)->t_wakeup);     \
        } while (0);

#define SET_WAKEUP_UNRESPONSIVE(DMN)                                           \
        do {                                                                   \
                (DMN)->t_wakeup = NULL;                                        \
                thread_add_timer_msec(master, wakeup_unresponsive, (DMN),      \
                                      FUZZY(gs.period), &(DMN)->t_wakeup);     \
        } while (0);

#define SET_WAKEUP_ECHO(DMN)                                                   \
        do {                                                                   \
                (DMN)->t_wakeup = NULL;                                        \
                thread_add_timer_msec(master, wakeup_send_echo, (DMN),         \
                                      FUZZY(gs.period), &(DMN)->t_wakeup);     \
        } while (0);

static int wakeup_down(struct thread *t_wakeup)
{
        struct daemon *dmn = THREAD_ARG(t_wakeup);

        dmn->t_wakeup = NULL;
        if (try_connect(dmn) < 0)
                SET_WAKEUP_DOWN(dmn);
        if ((dmn->connect_tries > 1) && (dmn->state != DAEMON_UP))
                try_restart(dmn);
        return 0;
}

static int wakeup_init(struct thread *t_wakeup)
{
        struct daemon *dmn = THREAD_ARG(t_wakeup);

        dmn->t_wakeup = NULL;
        if (try_connect(dmn) < 0) {
                SET_WAKEUP_DOWN(dmn);
                zlog_err("%s state -> down : initial connection attempt failed",
                         dmn->name);
                dmn->state = DAEMON_DOWN;
        }
        return 0;
}

static void daemon_down(struct daemon *dmn, const char *why)
{
        if (IS_UP(dmn) || (dmn->state == DAEMON_INIT))
                zlog_err("%s state -> down : %s", dmn->name, why);
        else if (gs.loglevel > LOG_DEBUG)
                zlog_debug("%s still down : %s", dmn->name, why);
        if (IS_UP(dmn))
                gs.numdown++;
        dmn->state = DAEMON_DOWN;
        if (dmn->fd >= 0) {
                close(dmn->fd);
                dmn->fd = -1;
        }
        THREAD_OFF(dmn->t_read);
        THREAD_OFF(dmn->t_write);
        THREAD_OFF(dmn->t_wakeup);
        if (try_connect(dmn) < 0)
                SET_WAKEUP_DOWN(dmn);
        phase_check();
}

static int handle_read(struct thread *t_read)
{
        struct daemon *dmn = THREAD_ARG(t_read);
        static const char resp[sizeof(PING_TOKEN) + 4] = PING_TOKEN "\n";
        char buf[sizeof(resp) + 100];
        ssize_t rc;
        struct timeval delay;

        dmn->t_read = NULL;
        if ((rc = read(dmn->fd, buf, sizeof(buf))) < 0) {
                char why[100];

                if (ERRNO_IO_RETRY(errno)) {
                        /* Pretend it never happened. */
                        SET_READ_HANDLER(dmn);
                        return 0;
                }
                snprintf(why, sizeof(why), "unexpected read error: %s",
                         safe_strerror(errno));
                daemon_down(dmn, why);
                return 0;
        }
        if (rc == 0) {
                daemon_down(dmn, "read returned EOF");
                return 0;
        }
        if (!dmn->echo_sent.tv_sec) {
                char why[sizeof(buf) + 100];
                snprintf(why, sizeof(why),
                         "unexpected read returns %d bytes: %.*s", (int)rc,
                         (int)rc, buf);
                daemon_down(dmn, why);
                return 0;
        }

        /* We are expecting an echo response: is there any chance that the
           response would not be returned entirely in the first read?  That
           seems inconceivable... */
        if ((rc != sizeof(resp)) || memcmp(buf, resp, sizeof(resp))) {
                char why[100 + sizeof(buf)];
                snprintf(why, sizeof(why),
                         "read returned bad echo response of %d bytes "
                         "(expecting %u): %.*s",
                         (int)rc, (u_int)sizeof(resp), (int)rc, buf);
                daemon_down(dmn, why);
                return 0;
        }

        time_elapsed(&delay, &dmn->echo_sent);
        dmn->echo_sent.tv_sec = 0;
        if (dmn->state == DAEMON_UNRESPONSIVE) {
                if (delay.tv_sec < gs.timeout) {
                        dmn->state = DAEMON_UP;
                        zlog_warn(
                                "%s state -> up : echo response received after %ld.%06ld "
                                "seconds",
                                dmn->name, (long)delay.tv_sec,
                                (long)delay.tv_usec);
                } else
                        zlog_warn(
                                "%s: slow echo response finally received after %ld.%06ld "
                                "seconds",
                                dmn->name, (long)delay.tv_sec,
                                (long)delay.tv_usec);
        } else if (gs.loglevel > LOG_DEBUG + 1)
                zlog_debug("%s: echo response received after %ld.%06ld seconds",
                           dmn->name, (long)delay.tv_sec, (long)delay.tv_usec);

        SET_READ_HANDLER(dmn);
        if (dmn->t_wakeup)
                thread_cancel(dmn->t_wakeup);
        SET_WAKEUP_ECHO(dmn);

        return 0;
}

/*
 * Wait till we notice that all daemons are ready before
 * we send we are ready to systemd
 */
static void daemon_send_ready(void)
{
        static int sent = 0;
        if (!sent && gs.numdown == 0) {
                FILE *fp;

                fp = fopen(DAEMON_VTY_DIR "/watchfrr.started", "w");
                fclose(fp);
#if defined HAVE_SYSTEMD
                zlog_notice(
                        "Watchfrr: Notifying Systemd we are up and running");
                systemd_send_started(master, 0);
#endif
                sent = 1;
        }
}

static void daemon_up(struct daemon *dmn, const char *why)
{
        dmn->state = DAEMON_UP;
        gs.numdown--;
        dmn->connect_tries = 0;
        zlog_notice("%s state -> up : %s", dmn->name, why);
        daemon_send_ready();
        if (gs.do_ping)
                SET_WAKEUP_ECHO(dmn);
        phase_check();
}

static int check_connect(struct thread *t_write)
{
        struct daemon *dmn = THREAD_ARG(t_write);
        int sockerr;
        socklen_t reslen = sizeof(sockerr);

        dmn->t_write = NULL;
        if (getsockopt(dmn->fd, SOL_SOCKET, SO_ERROR, (char *)&sockerr, &reslen)
            < 0) {
                zlog_warn("%s: check_connect: getsockopt failed: %s", dmn->name,
                          safe_strerror(errno));
                daemon_down(dmn,
                            "getsockopt failed checking connection success");
                return 0;
        }
        if ((reslen == sizeof(sockerr)) && sockerr) {
                char why[100];
                snprintf(
                        why, sizeof(why),
                        "getsockopt reports that connection attempt failed: %s",
                        safe_strerror(sockerr));
                daemon_down(dmn, why);
                return 0;
        }

        daemon_up(dmn, "delayed connect succeeded");
        return 0;
}

static int wakeup_connect_hanging(struct thread *t_wakeup)
{
        struct daemon *dmn = THREAD_ARG(t_wakeup);
        char why[100];

        dmn->t_wakeup = NULL;
        snprintf(why, sizeof(why),
                 "connection attempt timed out after %ld seconds", gs.timeout);
        daemon_down(dmn, why);
        return 0;
}

/* Making connection to protocol daemon. */
static int try_connect(struct daemon *dmn)
{
        int sock;
        struct sockaddr_un addr;
        socklen_t len;

        if (gs.loglevel > LOG_DEBUG + 1)
                zlog_debug("%s: attempting to connect", dmn->name);
        dmn->connect_tries++;

        memset(&addr, 0, sizeof(struct sockaddr_un));
        addr.sun_family = AF_UNIX;
        snprintf(addr.sun_path, sizeof(addr.sun_path), "%s/%s.vty", gs.vtydir,
                 dmn->name);
#ifdef HAVE_STRUCT_SOCKADDR_UN_SUN_LEN
        len = addr.sun_len = SUN_LEN(&addr);
#else
        len = sizeof(addr.sun_family) + strlen(addr.sun_path);
#endif /* HAVE_STRUCT_SOCKADDR_UN_SUN_LEN */

        /* Quick check to see if we might succeed before we go to the trouble
           of creating a socket. */
        if (access(addr.sun_path, W_OK) < 0) {
                if (errno != ENOENT)
                        zlog_err("%s: access to socket %s denied: %s",
                                 dmn->name, addr.sun_path,
                                 safe_strerror(errno));
                return -1;
        }

        if ((sock = socket(AF_UNIX, SOCK_STREAM, 0)) < 0) {
                zlog_err("%s(%s): cannot make socket: %s", __func__,
                         addr.sun_path, safe_strerror(errno));
                return -1;
        }

        if (set_nonblocking(sock) < 0 || set_cloexec(sock) < 0) {
                zlog_err("%s(%s): set_nonblocking/cloexec(%d) failed", __func__,
                         addr.sun_path, sock);
                close(sock);
                return -1;
        }

        if (connect(sock, (struct sockaddr *)&addr, len) < 0) {
                if ((errno != EINPROGRESS) && (errno != EWOULDBLOCK)) {
                        if (gs.loglevel > LOG_DEBUG)
                                zlog_debug("%s(%s): connect failed: %s",
                                           __func__, addr.sun_path,
                                           safe_strerror(errno));
                        close(sock);
                        return -1;
                }
                if (gs.loglevel > LOG_DEBUG)
                        zlog_debug("%s: connection in progress", dmn->name);
                dmn->state = DAEMON_CONNECTING;
                dmn->fd = sock;
                dmn->t_write = NULL;
                thread_add_write(master, check_connect, dmn, dmn->fd,
                                 &dmn->t_write);
                dmn->t_wakeup = NULL;
                thread_add_timer(master, wakeup_connect_hanging, dmn,
                                 gs.timeout, &dmn->t_wakeup);
                SET_READ_HANDLER(dmn);
                return 0;
        }

        dmn->fd = sock;
        SET_READ_HANDLER(dmn);
        daemon_up(dmn, "connect succeeded");
        return 1;
}

static int phase_hanging(struct thread *t_hanging)
{
        gs.t_phase_hanging = NULL;
        zlog_err("Phase [%s] hanging for %ld seconds, aborting phased restart",
                 phase_str[gs.phase], PHASE_TIMEOUT);
        gs.phase = PHASE_NONE;
        return 0;
}

static void set_phase(restart_phase_t new_phase)
{
        gs.phase = new_phase;
        if (gs.t_phase_hanging)
                thread_cancel(gs.t_phase_hanging);
        gs.t_phase_hanging = NULL;
        thread_add_timer(master, phase_hanging, NULL, PHASE_TIMEOUT,
                         &gs.t_phase_hanging);
}

static void phase_check(void)
{
        switch (gs.phase) {
        case PHASE_NONE:
                break;
        case PHASE_STOPS_PENDING:
                if (gs.numpids)
                        break;
                zlog_info(
                        "Phased restart: all routing daemon stop jobs have completed.");
                set_phase(PHASE_WAITING_DOWN);

        /*FALLTHRU*/
        case PHASE_WAITING_DOWN:
                if (gs.numdown + IS_UP(gs.special) < gs.numdaemons)
                        break;
                zlog_info("Phased restart: all routing daemons now down.");
                run_job(&gs.special->restart, "restart", gs.restart_command, 1,
                        1);
                set_phase(PHASE_ZEBRA_RESTART_PENDING);

        /*FALLTHRU*/
        case PHASE_ZEBRA_RESTART_PENDING:
                if (gs.special->restart.pid)
                        break;
                zlog_info("Phased restart: %s restart job completed.",
                          gs.special->name);
                set_phase(PHASE_WAITING_ZEBRA_UP);

        /*FALLTHRU*/
        case PHASE_WAITING_ZEBRA_UP:
                if (!IS_UP(gs.special))
                        break;
                zlog_info("Phased restart: %s is now up.", gs.special->name);
                {
                        struct daemon *dmn;
                        for (dmn = gs.daemons; dmn; dmn = dmn->next) {
                                if (dmn != gs.special)
                                        run_job(&dmn->restart, "start",
                                                gs.start_command, 1, 0);
                        }
                }
                gs.phase = PHASE_NONE;
                THREAD_OFF(gs.t_phase_hanging);
                zlog_notice("Phased global restart has completed.");
                break;
        }
}

static void try_restart(struct daemon *dmn)
{
        switch (gs.mode) {
        case MODE_MONITOR:
                return;
        case MODE_GLOBAL_RESTART:
                run_job(&gs.restart, "restart", gs.restart_command, 0, 1);
                break;
        case MODE_SEPARATE_RESTART:
                run_job(&dmn->restart, "restart", gs.restart_command, 0, 1);
                break;
        case MODE_PHASED_ZEBRA_RESTART:
                if (dmn != gs.special) {
                        if ((gs.special->state == DAEMON_UP)
                            && (gs.phase == PHASE_NONE))
                                run_job(&dmn->restart, "restart",
                                        gs.restart_command, 0, 1);
                        else
                                zlog_debug(
                                        "%s: postponing restart attempt because master %s daemon "
                                        "not up [%s], or phased restart in progress",
                                        dmn->name, gs.special->name,
                                        state_str[gs.special->state]);
                        break;
                }

        /*FALLTHRU*/
        case MODE_PHASED_ALL_RESTART:
                if ((gs.phase != PHASE_NONE) || gs.numpids) {
                        if (gs.loglevel > LOG_DEBUG + 1)
                                zlog_debug(
                                        "postponing phased global restart: restart already in "
                                        "progress [%s], or outstanding child processes [%d]",
                                        phase_str[gs.phase], gs.numpids);
                        break;
                }
                /* Is it too soon for a restart? */
                {
                        struct timeval delay;
                        if (time_elapsed(&delay, &gs.special->restart.time)
                                    ->tv_sec
                            < gs.special->restart.interval) {
                                if (gs.loglevel > LOG_DEBUG + 1)
                                        zlog_debug(
                                                "postponing phased global restart: "
                                                "elapsed time %ld < retry interval %ld",
                                                (long)delay.tv_sec,
                                                gs.special->restart.interval);
                                break;
                        }
                }
                run_job(&gs.restart, "restart", gs.restart_command, 0, 1);
                break;
        default:
                zlog_err("error: unknown restart mode %d", gs.mode);
                break;
        }
}

static int wakeup_unresponsive(struct thread *t_wakeup)
{
        struct daemon *dmn = THREAD_ARG(t_wakeup);

        dmn->t_wakeup = NULL;
        if (dmn->state != DAEMON_UNRESPONSIVE)
                zlog_err(
                        "%s: no longer unresponsive (now %s), "
                        "wakeup should have been cancelled!",
                        dmn->name, state_str[dmn->state]);
        else {
                SET_WAKEUP_UNRESPONSIVE(dmn);
                try_restart(dmn);
        }
        return 0;
}

static int wakeup_no_answer(struct thread *t_wakeup)
{
        struct daemon *dmn = THREAD_ARG(t_wakeup);

        dmn->t_wakeup = NULL;
        dmn->state = DAEMON_UNRESPONSIVE;
        zlog_err(
                "%s state -> unresponsive : no response yet to ping "
                "sent %ld seconds ago",
                dmn->name, gs.timeout);
        if (gs.unresponsive_restart) {
                SET_WAKEUP_UNRESPONSIVE(dmn);
                try_restart(dmn);
        }
        return 0;
}

static int wakeup_send_echo(struct thread *t_wakeup)
{
        static const char echocmd[] = "echo " PING_TOKEN;
        ssize_t rc;
        struct daemon *dmn = THREAD_ARG(t_wakeup);

        dmn->t_wakeup = NULL;
        if (((rc = write(dmn->fd, echocmd, sizeof(echocmd))) < 0)
            || ((size_t)rc != sizeof(echocmd))) {
                char why[100 + sizeof(echocmd)];
                snprintf(why, sizeof(why),
                         "write '%s' returned %d instead of %u", echocmd,
                         (int)rc, (u_int)sizeof(echocmd));
                daemon_down(dmn, why);
        } else {
                gettimeofday(&dmn->echo_sent, NULL);
                dmn->t_wakeup = NULL;
                thread_add_timer(master, wakeup_no_answer, dmn, gs.timeout,
                                 &dmn->t_wakeup);
        }
        return 0;
}

static void sigint(void)
{
        zlog_notice("Terminating on signal");
        systemd_send_stopping();
        exit(0);
}

static int valid_command(const char *cmd)
{
        char *p;

        return ((p = strchr(cmd, '%')) != NULL) && (*(p + 1) == 's')
               && !strchr(p + 1, '%');
}

/* This is an ugly hack to circumvent problems with passing command-line
   arguments that contain spaces.  The fix is to use a configuration file. */
static char *translate_blanks(const char *cmd, const char *blankstr)
{
        char *res;
        char *p;
        size_t bslen = strlen(blankstr);

        if (!(res = strdup(cmd))) {
                perror("strdup");
                exit(1);
        }
        while ((p = strstr(res, blankstr)) != NULL) {
                *p = ' ';
                if (bslen != 1)
                        memmove(p + 1, p + bslen, strlen(p + bslen) + 1);
        }
        return res;
}

struct zebra_privs_t watchfrr_privs = {
#ifdef VTY_GROUP
        .vty_group = VTY_GROUP,
#endif
};

static struct quagga_signal_t watchfrr_signals[] = {
        {
                .signal = SIGINT,
                .handler = sigint,
        },
        {
                .signal = SIGTERM,
                .handler = sigint,
        },
        {
                .signal = SIGCHLD,
                .handler = sigchild,
        },
};

FRR_DAEMON_INFO(watchfrr, WATCHFRR,
                .flags = FRR_NO_PRIVSEP | FRR_NO_TCPVTY | FRR_LIMITED_CLI
                         | FRR_NO_CFG_PID_DRY | FRR_NO_ZCLIENT,

                .printhelp = printhelp,
                .copyright = "Copyright 2004 Andrew J. Schorr",

                .signals = watchfrr_signals,
                .n_signals = array_size(watchfrr_signals),

                .privs = &watchfrr_privs, )

int main(int argc, char **argv)
{
        int opt;
        const char *pidfile = DEFAULT_PIDFILE;
        const char *special = "zebra";
        const char *blankstr = NULL;

        frr_preinit(&watchfrr_di, argc, argv);
        progname = watchfrr_di.progname;

        frr_opt_add("aAb:dek:l:i:p:r:R:S:s:t:T:z", longopts, "");

        gs.restart.name = "all";
        while ((opt = frr_getopt(argc, argv, NULL)) != EOF) {
                switch (opt) {
                case 0:
                        break;
                case 'a':
                        if ((gs.mode != MODE_MONITOR)
                            && (gs.mode != MODE_SEPARATE_RESTART)) {
                                fputs("Ambiguous operating mode selected.\n",
                                      stderr);
                                frr_help_exit(1);
                        }
                        gs.mode = MODE_PHASED_ZEBRA_RESTART;
                        break;
                case 'A':
                        if ((gs.mode != MODE_MONITOR)
                            && (gs.mode != MODE_SEPARATE_RESTART)) {
                                fputs("Ambiguous operating mode selected.\n",
                                      stderr);
                                frr_help_exit(1);
                        }
                        gs.mode = MODE_PHASED_ALL_RESTART;
                        break;
                case 'b':
                        blankstr = optarg;
                        break;
                case 'e':
                        gs.do_ping = 0;
                        break;
                case 'k':
                        if (!valid_command(optarg)) {
                                fprintf(stderr,
                                        "Invalid kill command, must contain '%%s': %s\n",
                                        optarg);
                                frr_help_exit(1);
                        }
                        gs.stop_command = optarg;
                        break;
                case 'l': {
                        char garbage[3];
                        if ((sscanf(optarg, "%d%1s", &gs.loglevel, garbage)
                             != 1)
                            || (gs.loglevel < LOG_EMERG)) {
                                fprintf(stderr,
                                        "Invalid loglevel argument: %s\n",
                                        optarg);
                                frr_help_exit(1);
                        }
                } break;
                case OPTION_MINRESTART: {
                        char garbage[3];
                        if ((sscanf(optarg, "%ld%1s", &gs.min_restart_interval,
                                    garbage)
                             != 1)
                            || (gs.min_restart_interval < 0)) {
                                fprintf(stderr,
                                        "Invalid min_restart_interval argument: %s\n",
                                        optarg);
                                frr_help_exit(1);
                        }
                } break;
                case OPTION_MAXRESTART: {
                        char garbage[3];
                        if ((sscanf(optarg, "%ld%1s", &gs.max_restart_interval,
                                    garbage)
                             != 1)
                            || (gs.max_restart_interval < 0)) {
                                fprintf(stderr,
                                        "Invalid max_restart_interval argument: %s\n",
                                        optarg);
                                frr_help_exit(1);
                        }
                } break;
                case 'i': {
                        char garbage[3];
                        int period;
                        if ((sscanf(optarg, "%d%1s", &period, garbage) != 1)
                            || (gs.period < 1)) {
                                fprintf(stderr,
                                        "Invalid interval argument: %s\n",
                                        optarg);
                                frr_help_exit(1);
                        }
                        gs.period = 1000 * period;
                } break;
                case 'p':
                        pidfile = optarg;
                        break;
                case 'r':
                        if ((gs.mode == MODE_GLOBAL_RESTART)
                            || (gs.mode == MODE_SEPARATE_RESTART)) {
                                fputs("Ambiguous operating mode selected.\n",
                                      stderr);
                                frr_help_exit(1);
                        }
                        if (!valid_command(optarg)) {
                                fprintf(stderr,
                                        "Invalid restart command, must contain '%%s': %s\n",
                                        optarg);
                                frr_help_exit(1);
                        }
                        gs.restart_command = optarg;
                        if (gs.mode == MODE_MONITOR)
                                gs.mode = MODE_SEPARATE_RESTART;
                        break;
                case 'R':
                        if (gs.mode != MODE_MONITOR) {
                                fputs("Ambiguous operating mode selected.\n",
                                      stderr);
                                frr_help_exit(1);
                        }
                        if (strchr(optarg, '%')) {
                                fprintf(stderr,
                                        "Invalid restart-all arg, must not contain '%%s': %s\n",
                                        optarg);
                                frr_help_exit(1);
                        }
                        gs.restart_command = optarg;
                        gs.mode = MODE_GLOBAL_RESTART;
                        break;
                case 's':
                        if (!valid_command(optarg)) {
                                fprintf(stderr,
                                        "Invalid start command, must contain '%%s': %s\n",
                                        optarg);
                                frr_help_exit(1);
                        }
                        gs.start_command = optarg;
                        break;
                case 'S':
                        gs.vtydir = optarg;
                        break;
                case 't': {
                        char garbage[3];
                        if ((sscanf(optarg, "%ld%1s", &gs.timeout, garbage)
                             != 1)
                            || (gs.timeout < 1)) {
                                fprintf(stderr,
                                        "Invalid timeout argument: %s\n",
                                        optarg);
                                frr_help_exit(1);
                        }
                } break;
                case 'T': {
                        char garbage[3];
                        if ((sscanf(optarg, "%ld%1s", &gs.restart_timeout,
                                    garbage)
                             != 1)
                            || (gs.restart_timeout < 1)) {
                                fprintf(stderr,
                                        "Invalid restart timeout argument: %s\n",
                                        optarg);
                                frr_help_exit(1);
                        }
                } break;
                case 'z':
                        gs.unresponsive_restart = 1;
                        break;
                default:
                        fputs("Invalid option.\n", stderr);
                        frr_help_exit(1);
                }
        }

        if (gs.unresponsive_restart && (gs.mode == MODE_MONITOR)) {
                fputs("Option -z requires a -r or -R restart option.\n",
                      stderr);
                frr_help_exit(1);
        }
        switch (gs.mode) {
        case MODE_MONITOR:
                if (gs.restart_command || gs.start_command || gs.stop_command) {
                        fprintf(stderr,
                                "No kill/(re)start commands needed for %s mode.\n",
                                mode_str[gs.mode]);
                        frr_help_exit(1);
                }
                break;
        case MODE_GLOBAL_RESTART:
        case MODE_SEPARATE_RESTART:
                if (!gs.restart_command || gs.start_command
                    || gs.stop_command) {
                        fprintf(stderr,
                                "No start/kill commands needed in [%s] mode.\n",
                                mode_str[gs.mode]);
                        frr_help_exit(1);
                }
                break;
        case MODE_PHASED_ZEBRA_RESTART:
        case MODE_PHASED_ALL_RESTART:
                if (!gs.restart_command || !gs.start_command
                    || !gs.stop_command) {
                        fprintf(stderr,
                                "Need start, kill, and restart commands in [%s] mode.\n",
                                mode_str[gs.mode]);
                        frr_help_exit(1);
                }
                break;
        }

        if (blankstr) {
                if (gs.restart_command)
                        gs.restart_command =
                                translate_blanks(gs.restart_command, blankstr);
                if (gs.start_command)
                        gs.start_command =
                                translate_blanks(gs.start_command, blankstr);
                if (gs.stop_command)
                        gs.stop_command =
                                translate_blanks(gs.stop_command, blankstr);
        }

        gs.restart.interval = gs.min_restart_interval;

        master = frr_init();

        zlog_set_level(ZLOG_DEST_MONITOR, ZLOG_DISABLED);
        if (watchfrr_di.daemon_mode) {
                zlog_set_level(ZLOG_DEST_SYSLOG, MIN(gs.loglevel, LOG_DEBUG));
                if (daemon(0, 0) < 0) {
                        fprintf(stderr, "Watchfrr daemon failed: %s",
                                strerror(errno));
                        exit(1);
                }
        } else
                zlog_set_level(ZLOG_DEST_STDOUT, MIN(gs.loglevel, LOG_DEBUG));

        watchfrr_vty_init();

        frr_vty_serv();

        {
                int i;
                struct daemon *tail = NULL;

                for (i = optind; i < argc; i++) {
                        struct daemon *dmn;

                        if (!(dmn = (struct daemon *)calloc(1, sizeof(*dmn)))) {
                                fprintf(stderr, "calloc(1,%u) failed: %s\n",
                                        (u_int)sizeof(*dmn),
                                        safe_strerror(errno));
                                return 1;
                        }
                        dmn->name = dmn->restart.name = argv[i];
                        dmn->state = DAEMON_INIT;
                        gs.numdaemons++;
                        gs.numdown++;
                        dmn->fd = -1;
                        dmn->t_wakeup = NULL;
                        thread_add_timer_msec(master, wakeup_init, dmn,
                                              100 + (random() % 900),
                                              &dmn->t_wakeup);
                        dmn->restart.interval = gs.min_restart_interval;
                        if (tail)
                                tail->next = dmn;
                        else
                                gs.daemons = dmn;
                        tail = dmn;

                        if (((gs.mode == MODE_PHASED_ZEBRA_RESTART)
                             || (gs.mode == MODE_PHASED_ALL_RESTART))
                            && !strcmp(dmn->name, special))
                                gs.special = dmn;
                }
        }
        if (!gs.daemons) {
                fputs("Must specify one or more daemons to monitor.\n", stderr);
                frr_help_exit(1);
        }
        if (((gs.mode == MODE_PHASED_ZEBRA_RESTART)
             || (gs.mode == MODE_PHASED_ALL_RESTART))
            && !gs.special) {
                fprintf(stderr,
                        "In mode [%s], but cannot find master daemon %s\n",
                        mode_str[gs.mode], special);
                frr_help_exit(1);
        }

        /* Make sure we're not already running. */
        pid_output(pidfile);

        /* Announce which daemons are being monitored. */
        {
                struct daemon *dmn;
                size_t len = 0;

                for (dmn = gs.daemons; dmn; dmn = dmn->next)
                        len += strlen(dmn->name) + 1;

                {
                        char buf[len + 1];
                        char *p = buf;

                        for (dmn = gs.daemons; dmn; dmn = dmn->next) {
                                if (p != buf)
                                        *p++ = ' ';
                                strcpy(p, dmn->name);
                                p += strlen(p);
                        }
                        zlog_notice("%s %s watching [%s], mode [%s]", progname,
                                    FRR_VERSION, buf, mode_str[gs.mode]);
                }
        }

        {
                struct thread thread;

                while (thread_fetch(master, &thread))
                        thread_call(&thread);
        }

        systemd_send_stopping();
        /* Not reached. */
        return 0;
}