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autossh.c
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/*
* Start an ssh session (or tunnel) and monitor it.
* If it fails or blocks, restart it.
*
* From the example of rstunnel.
*
* Copyright (c) Carson Harding, 2002-2008.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are freely permitted.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
* INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
* AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
* THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
* OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
*/
#include "config.h"
#include <sys/types.h>
#include <sys/time.h>
#ifndef HAVE_SOCKLEN_T
typedef int32_t socklen_t;
#endif
#include <sys/socket.h>
#include <sys/utsname.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <fcntl.h>
#include <netdb.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <signal.h>
#include <limits.h>
#include <sys/wait.h>
#include <setjmp.h>
#include <stdarg.h>
#include <syslog.h>
#include <time.h>
#include <errno.h>
#ifndef HAVE_POLL
# ifdef HAVE_SELECT
# include "fakepoll.h"
# else
# error "System lacks both select() and poll()!"
# endif
#else
# include <poll.h>
#endif
#ifndef __attribute__
# if __GNUC__ < 2 || (__GNUC__ == 2 && __GNUC_MINOR__ < 8) || __STRICT_ANSI__
# define __attribute__(x)
# endif
#endif
#ifndef _PATH_DEVNULL
# define _PATH_DEVNULL "/dev/null"
#endif
#ifndef HAVE_DAEMON
# include "daemon.h"
#endif
#ifdef HAVE___PROGNAME
extern char *__progname;
#else
char *__progname;
#endif
const char *rcsid = "$Id: autossh.c,v 1.82 2011/10/12 20:29:22 harding Exp $";
#ifndef SSH_PATH
# define SSH_PATH "/usr/bin/ssh"
#endif
#define POLL_TIME 600 /* 10 minutes default */
#define GATE_TIME 30 /* 30 seconds default */
#define MAX_LIFETIME 0 /* default max lifetime of forever */
#define TIMEO_NET 15000 /* poll on accept() and io (msecs) */
#define MAX_CONN_TRIES 3 /* how many attempts */
#define MAX_START (-1) /* max # of runs; <0 == forever */
#define MAX_MESSAGE 64 /* max length of message we can add */
#define P_CONTINUE 0 /* continue monitoring */
#define P_RESTART 1 /* restart ssh process */
#define P_EXIT 2 /* exit */
#define L_FILELOG 0x01 /* log to file */
#define L_SYSLOG 0x02 /* log to syslog */
#define NO_RD_SOCK -2 /* magic flag for echo: no read socket */
#define OPTION_STRING "M:V1246ab:c:e:fgi:kl:m:no:p:qstvw:xyACD:F:I:MKL:NO:PR:S:TVXY"
int logtype = L_SYSLOG; /* default log to syslog */
int loglevel = LOG_INFO; /* default loglevel */
int syslog_perror; /* use PERROR option? */
FILE *flog; /* log file */
char *writep; /* write port as string */
char readp[16]; /* read port as string */
char *echop; /* echo port as string */
char *mhost = "127.0.0.1"; /* host in port forwards */
char *env_port; /* port spec'd in environment */
char *echo_message = ""; /* message to append to echo string */
char *pid_file_name; /* path to pid file */
int pid_file_created; /* we have created pid file */
time_t pid_start_time; /* time autossh process started */
int poll_time = POLL_TIME; /* default connection poll time */
int first_poll_time = POLL_TIME; /* initial connection poll time */
double gate_time = GATE_TIME; /* time to "make it out of the gate" */
int max_start = MAX_START; /* how many times to run (default no limit) */
double max_lifetime = MAX_LIFETIME; /* how long can the process/daemon live */
int net_timeout = TIMEO_NET; /* timeout on network data */
char *ssh_path = SSH_PATH; /* default path to ssh */
int start_count; /* # of times exec()d ssh */
time_t start_time; /* time we exec()d ssh */
#if defined(__CYGWIN__)
int ntservice; /* set some stuff for running as nt service */
#endif
int newac; /* argc, argv for ssh */
char **newav;
#define START_AV_SZ 16
int cchild; /* current child */
volatile sig_atomic_t restart_ssh; /* signalled to restart ssh child */
volatile sig_atomic_t dolongjmp;
sigjmp_buf jumpbuf;
void usage(int code) __attribute__ ((__noreturn__));
void get_env_args(void);
void add_arg(char *s);
void strip_arg(char *arg, char ch, char *opts);
void ssh_run(int sock, char **argv);
int ssh_watch(int sock);
int ssh_wait(int options);
void ssh_kill(void);
int conn_test(int sock, char *host, char *write_port);
int conn_poll_for_accept(int sock, struct pollfd *pfd);
int conn_send_and_receive(char *rp, char *wp, size_t len,
struct pollfd *pfd, int ntopoll);
#ifndef HAVE_ADDRINFO
void conn_addr(char *host, char *port, struct sockaddr_in *resp);
#else
void conn_addr(char *host, char *port, struct addrinfo **resp);
#endif
int conn_listen(char *host, char *port);
int conn_remote(char *host, char *port);
void grace_time(time_t last_start);
void unlink_pid_file(void);
void errlog(int level, char *fmt, ...)
__attribute__ ((__format__ (__printf__, 2, 3)));
void xerrlog(int level, char *fmt, ...)
__attribute__ ((__format__ (__printf__, 2, 3)));
void doerrlog(int level, char *fmt, va_list ap);
char *timestr(void);
void sig_catch(int sig);
int exceeded_lifetime(void);
void
usage(int code)
{
fprintf(code ? stderr : stdout,
"usage: %s [-V] [-M monitor_port[:echo_port]] [-f] [SSH_OPTIONS]\n",
__progname);
if (code) {
fprintf(stderr, "\n");
fprintf(stderr,
" -M specifies monitor port. May be overridden by"
" environment\n"
" variable AUTOSSH_PORT. 0 turns monitoring"
" loop off.\n"
" Alternatively, a port for an echo service on"
" the remote\n"
" machine may be specified. (Normally port 7.)\n");
fprintf(stderr,
" -f run in background (autossh handles this, and"
" does not\n"
" pass it to ssh.)\n");
fprintf(stderr,
" -V print autossh version and exit.\n");
fprintf(stderr, "\n");
fprintf(stderr, "Environment variables are:\n");
fprintf(stderr,
" AUTOSSH_GATETIME "
"- how long must an ssh session be established\n"
" "
" before we decide it really was established\n"
" "
" (in seconds). Default is %d seconds; use of -f\n"
" "
" flag sets this to 0.\n", GATE_TIME);
fprintf(stderr,
" AUTOSSH_LOGFILE "
"- file to log to (default is to use the syslog\n"
" "
" facility)\n");
fprintf(stderr,
" AUTOSSH_LOGLEVEL "
"- level of log verbosity\n");
fprintf(stderr,
" AUTOSSH_MAXLIFETIME "
"- set the maximum time to live (seconds)\n");
fprintf(stderr,
" AUTOSSH_MAXSTART "
"- max times to restart (default is no limit)\n");
fprintf(stderr,
" AUTOSSH_MESSAGE "
"- message to append to echo string (max 64 bytes)\n");
#if defined(__CYGWIN__)
fprintf(stderr,
" AUTOSSH_NTSERVICE "
"- tweak some things for running under cygrunsrv\n");
#endif
fprintf(stderr,
" AUTOSSH_PATH "
"- path to ssh if not default\n");
fprintf(stderr,
" AUTOSSH_PIDFILE "
"- write pid to this file\n");
fprintf(stderr,
" AUTOSSH_POLL "
"- how often to check the connection (seconds)\n");
fprintf(stderr,
" AUTOSSH_FIRST_POLL "
"- time before first connection check (seconds)\n");
fprintf(stderr,
" AUTOSSH_PORT "
"- port to use for monitor connection\n");
fprintf(stderr,
" AUTOSSH_DEBUG "
"- turn logging to maximum verbosity and log to\n"
" "
" stderr\n");
fprintf(stderr, "\n");
}
exit(code);
}
int
main(int argc, char **argv)
{
int i;
int n;
int ch;
char *s;
int wp, rp, ep = 0;
char wmbuf[256], rmbuf[256];
FILE *pid_file;
int sock = -1;
int done_fwds = 0;
int runasdaemon = 0;
int sawargstop = 0;
#if defined(__CYGWIN__)
int sawoptionn = 0;
#endif
#ifndef HAVE___PROGNAME
__progname = "autossh";
#endif
/*
* set up options from environment
*/
get_env_args();
/*
* We accept all ssh args, and quietly pass them on
* to ssh when we call it.
*/
while ((ch = getopt(argc, argv, OPTION_STRING)) != -1) {
switch(ch) {
case 'M':
if (!env_port)
writep = optarg;
break;
case 'V':
fprintf(stdout, "%s %s\n", __progname, VER);
exit(0);
break;
case 'f':
runasdaemon = 1;
break;
#if defined(__CYGWIN__)
case 'N':
sawoptionn = 1;
break;
#endif
case '?':
usage(1);
break;
default:
/* other options get passed to ssh */
break;
}
}
/* if we got it from the environment */
if (env_port)
writep = env_port;
/*
* We must at least have a monitor port and a remote host.
*/
if (env_port) {
if (argc < 2)
usage(1);
} else if (!writep || argc < 4)
usage(1);
if (logtype & L_SYSLOG)
openlog(__progname, LOG_PID|syslog_perror, LOG_USER);
/*
* Check for echo port
*/
if ((s = strchr(writep, ':')) != NULL) {
*s = '\0';
echop = s + 1;
ep = strtoul(echop, &s, 0);
if (*echop == '\0' || *s != '\0' || ep == 0)
xerrlog(LOG_ERR, "invalid echo port \"%s\"", echop);
}
/*
* Check, and get the read port (write port + 1);
* then construct port-forwarding arguments for ssh.
*/
wp = strtoul(writep, &s, 0);
if (*writep == '\0' || *s != '\0')
xerrlog(LOG_ERR, "invalid port \"%s\"", writep);
if (wp == 0) {
errlog(LOG_INFO, "port set to 0, monitoring disabled");
writep = NULL;
}
else if (wp > 65534 || wp < 0)
xerrlog(LOG_ERR, "monitor port (%d) out of range", wp);
else {
rp = wp+1;
/* all this for solaris; we could use asprintf() */
(void)snprintf(readp, sizeof(readp), "%d", rp);
/* port-forward arg strings */
n = snprintf(wmbuf, sizeof(wmbuf), "%d:%s:%d", wp, mhost,
echop ? ep : wp);
if (n > sizeof(wmbuf))
xerrlog(LOG_ERR,
"overflow building forwarding string");
if (!echop) {
n = snprintf(rmbuf, sizeof(rmbuf), "%d:%s:%d",
wp, mhost, rp);
if (n > sizeof(rmbuf))
xerrlog(LOG_ERR,
"overflow building forwarding string");
}
}
/*
* Adjust timeouts if necessary: net_timeout is first
* the timeout for accept and then for io, so if the
* poll_time is set less than 2 timeouts, the timeouts need
* to be adjusted to be at least 1/2. Perhaps there should be
* be some padding here as well....
*/
if ((poll_time * 1000) / 2 < net_timeout) {
net_timeout = (poll_time * 1000) / 2;
errlog(LOG_INFO,
"short poll time: adjusting net timeouts to %d",
net_timeout);
}
/*
* Build a new arg list, skipping -f, -M and inserting
* port forwards.
*/
add_arg(ssh_path);
#if defined(__CYGWIN__)
if (ntservice && !sawoptionn)
add_arg("-N");
#endif
for (i = 1; i < argc; i++) {
/*
* We step past the first '--', taking it as ours
* (autossh's). Any further ones we pass to ssh.
*/
if (argv[i][0] == '-' && argv[i][1] == '-') {
if (!sawargstop) {
sawargstop = 1;
continue;
}
}
if (wp && env_port && !done_fwds) {
add_arg("-L");
add_arg(wmbuf);
if (!echop) {
add_arg("-R");
add_arg(rmbuf);
}
done_fwds = 1;
} else if (!sawargstop && argv[i][0] == '-' && argv[i][1] == 'M') {
if (argv[i][2] == '\0')
i++;
if (wp && !done_fwds) {
add_arg("-L");
add_arg(wmbuf);
if (!echop) {
add_arg("-R");
add_arg(rmbuf);
}
done_fwds = 1;
}
continue;
}
/* look for -f in option args and strip out */
strip_arg(argv[i], 'f', OPTION_STRING);
add_arg(argv[i]);
}
/*
* Only if we're doing the network monitor thing.
* Socket once opened stays open for listening for
* the duration of the program.
*/
if (writep) {
if (!echop) {
sock = conn_listen(mhost, readp);
/* set close-on-exec */
(void)fcntl(sock, F_SETFD, FD_CLOEXEC);
} else
sock = NO_RD_SOCK;
}
if (runasdaemon) {
if (daemon(0, 0) == -1) {
xerrlog(LOG_ERR, "run as daemon failed: %s",
strerror(errno));
}
/*
* If running as daemon, the user likely wants it
* to just run and not fail early (perhaps machines
* are coming up, etc.)
*/
gate_time = 0;
}
if (pid_file_name) {
pid_file = fopen(pid_file_name, "w");
if (!pid_file) {
xerrlog(LOG_ERR, "cannot open pid file \"%s\": %s",
pid_file_name, strerror(errno));
}
pid_file_created = 1;
atexit(unlink_pid_file);
if (fprintf(pid_file, "%d\n", (int)getpid()) == 0)
xerrlog(LOG_ERR, "write failed to pid file \"%s\": %s",
pid_file_name, strerror(errno));
fflush(pid_file);
fclose(pid_file);
}
ssh_run(sock, newav);
if (sock >= 0) {
shutdown(sock, SHUT_RDWR);
close(sock);
}
if (logtype & L_SYSLOG)
closelog();
exit(0);
}
/*
* Add an argument to the argument array.
*/
void
add_arg(char *s)
{
char *p;
size_t len;
static size_t newamax = START_AV_SZ;
len = strlen(s);
if (len == 0)
return;
if (!newav) {
newav = malloc(START_AV_SZ * sizeof(char *));
if (!newav)
xerrlog(LOG_ERR, "malloc: %s", strerror(errno));
} else if (newac >= newamax-1) {
newamax *= 2;
newav = realloc(newav, newamax * sizeof(char *));
if (!newav)
xerrlog(LOG_ERR, "realloc: %s", strerror(errno));
}
p = malloc(len+1);
if (!p) xerrlog(LOG_ERR, "malloc: %s", strerror(errno));
memmove(p, s, len);
p[len] = '\0';
newav[newac++] = p;
newav[newac] = NULL;
return;
}
/*
* strip an argument option from an option string; strings that
* end up with just a '-' become zero length (add_arg() will
* skip them). An option that enters as '-' is untouched.
*
*/
void
strip_arg(char *arg, char ch, char *opts)
{
char *f, *o;
size_t len;
if (arg[0] == '-' && arg[1] != '\0') {
for (len = strlen(arg), f = arg; *f != '\0'; f++, len--) {
/*
* If f in option string and next char is ':' then
* what follows is a parameter to the flag, and
* what we're stripping may be valid in it. We do
* not validate f in opts: that is really someone
* else's job, and the options may change. In that
* case, this provides a best effort. This is
* terribly inefficient.
*/
if ((o = strchr(opts, *f)) != NULL) {
if (*(o+1) == ':')
return;
}
if (*f == ch)
(void)memmove(f, f+1, len);
}
/* left with "-" alone? then truncate */
if (arg[1] == '\0')
arg[0] = '\0';
}
return;
}
/*
* Ugly, but as we've used so many command args...
*/
void
get_env_args(void)
{
char *s;
char *t;
if ((s = getenv("AUTOSSH_PATH")) != NULL)
ssh_path = s;
if ((s = getenv("AUTOSSH_DEBUG")) != NULL) {
#ifdef HAVE_LOG_PERROR
syslog_perror = LOG_PERROR;
#else
syslog_perror = 0;
logtype |= L_FILELOG;
flog = stderr;
#endif
loglevel = LOG_DEBUG;
} else if ((s = getenv("AUTOSSH_LOGLEVEL")) != NULL) {
loglevel = strtoul(s, &t, 0);
if (*s == '\0' || *t != '\0' ||
loglevel < LOG_EMERG || loglevel > LOG_DEBUG)
xerrlog(LOG_ERR, "invalid log level \"%s\"", s);
}
if ((s = getenv("AUTOSSH_FIRST_POLL")) != NULL) {
first_poll_time = strtoul(s, &t, 0);
if (*s == '\0' || first_poll_time == 0 || *t != '\0' )
xerrlog(LOG_ERR,
"invalid first poll time \"%s\"", s);
if (first_poll_time <= 0)
first_poll_time = POLL_TIME;
}
if ((s = getenv("AUTOSSH_POLL")) != NULL) {
poll_time = strtoul(s, &t, 0);
if (*s == '\0' || poll_time == 0 || *t != '\0' )
xerrlog(LOG_ERR,
"invalid poll time \"%s\"", s);
if (poll_time <= 0)
poll_time = POLL_TIME;
}
if ((s = getenv("AUTOSSH_GATETIME")) != NULL) {
gate_time = (double)strtol(s, &t, 0);
if (*s == '\0' || gate_time < 0 || *t != '\0' )
xerrlog(LOG_ERR, "invalid gate time \"%s\"", s);
}
if ((s = getenv("AUTOSSH_MAXSTART")) != NULL) {
max_start = (int)strtol(s, &t, 0);
if (*s == '\0' || max_start < 0 || *t != '\0')
xerrlog(LOG_ERR, "invalid max start number \"%s\"", s);
}
if ((s = getenv("AUTOSSH_MESSAGE")) != NULL) {
if (*s != '\0')
echo_message = s;
if (strlen(echo_message) > MAX_MESSAGE)
xerrlog(LOG_ERR, "echo message may only be %d bytes long",
MAX_MESSAGE);
}
if ((s = getenv("AUTOSSH_PORT")) != NULL)
if (*s != '\0')
env_port = s;
if ((s = getenv("AUTOSSH_MAXLIFETIME")) != NULL) {
max_lifetime = (double)strtoul(s, &t, 0);
if (*s == '\0' || *t != '\0' )
xerrlog(LOG_ERR,
"invalid max lifetime \"%s\"", s);
/* can't really be < 0, as converted as unsigned long */
if (max_lifetime <= 0 )
max_lifetime = MAX_LIFETIME;
else {
if (poll_time > max_lifetime) {
errlog( LOG_INFO,
"poll time is greater then lifetime,"
" dropping poll time to %.0f", max_lifetime );
poll_time = max_lifetime;
}
if (first_poll_time > max_lifetime) {
errlog( LOG_INFO,
"first poll time is greater then lifetime,"
" dropping first poll time to %.0f", max_lifetime );
first_poll_time = max_lifetime;
}
time(&pid_start_time);
}
}
if ((s = getenv("AUTOSSH_PIDFILE")) != NULL)
if (*s != '\0')
pid_file_name = s;
#if defined(__CYGWIN__)
if ((s = getenv("AUTOSSH_NTSERVICE")) != NULL) {
if (*s != '\0' && strncasecmp("yes", s, strlen(s)) == 0) {
ntservice = 1;
logtype = L_FILELOG;
flog = stdout;
}
}
#endif
/*
* Look for this after nt service; in case we may wish to log
* elsewhere than stdout when running under cygrunsrv.
*/
if ((s = getenv("AUTOSSH_LOGFILE")) != NULL) {
flog = fopen(s, "a");
if (!flog)
xerrlog(LOG_ERR, "%s: %s", s, strerror(errno));
logtype = L_FILELOG;
}
return;
}
/*
* Run ssh
*/
void
ssh_run(int sock, char **av)
{
struct sigaction act;
struct timeval tv;
act.sa_handler = sig_catch;
sigemptyset(&act.sa_mask);
act.sa_flags = 0;
sigaction(SIGTERM, &act, NULL);
sigaction(SIGINT, &act, NULL);
sigaction(SIGHUP, &act, NULL);
sigaction(SIGUSR1, &act, NULL);
sigaction(SIGUSR2, &act, NULL);
sigaction(SIGCHLD, &act, NULL);
act.sa_flags |= SA_RESTART;
sigaction(SIGALRM, &act, NULL);
/*
* There are much better things. and we all wait
* for solaris to get /dev/random.
*/
gettimeofday(&tv, NULL);
srandom(getpid() ^ tv.tv_usec ^ tv.tv_sec);
while (max_start < 0 || start_count < max_start) {
if (exceeded_lifetime())
return;
restart_ssh = 0;
start_count++;
grace_time(start_time);
time(&start_time);
if (max_start < 0)
errlog(LOG_INFO, "starting ssh (count %d)",
start_count);
else
errlog(LOG_INFO, "starting ssh (count %d of %d)",
start_count, max_start);
cchild = fork();
switch (cchild) {
case 0:
errlog(LOG_DEBUG, "execing %s", av[0]);
execvp(av[0], av);
xerrlog(LOG_ERR, "%s: %s", av[0], strerror(errno));
/* else can loop restarting! */
kill(SIGTERM, getppid());
exit(1);
break;
case -1:
cchild = 0;
xerrlog(LOG_ERR, "fork: %s", strerror(errno));
break;
default:
errlog(LOG_INFO, "ssh child pid is %d", (int)cchild);
if (ssh_watch(sock) == P_EXIT)
return;
break;
}
}
errlog(LOG_INFO, "max start count reached; exiting");
}
/*
* Periodically test network connection. On signals, determine what
* happened or what to do with child. Return as necessary for exit
* or restart of child.
*/
int
ssh_watch(int sock)
{
int r;
int val;
static int secs_left;
int my_poll_time = first_poll_time;
time_t now;
double secs_to_shutdown;
#if defined(HAVE_SETPROCTITLE)
setproctitle("parent of %d (%d)",
(int)cchild, start_count);
#endif
for (;;) {
if (restart_ssh) {
errlog(LOG_INFO, "signalled to kill and restart ssh");
ssh_kill();
return P_RESTART;
}
if ((val = sigsetjmp(jumpbuf, 1)) == 0) {
errlog(LOG_DEBUG, "check on child %d", cchild);
/* poll for expired child */
r = ssh_wait(WNOHANG);
if (r != P_CONTINUE) {
errlog(LOG_DEBUG,
"expired child, returning %d", r);
return r;
}
secs_left = alarm(0);
if (secs_left == 0)
secs_left = my_poll_time;
my_poll_time = poll_time;
if (max_lifetime != 0) {
time(&now);
secs_to_shutdown = max_lifetime - difftime(now,pid_start_time);
if (secs_to_shutdown < poll_time)
secs_left = secs_to_shutdown;
}
errlog(LOG_DEBUG,
"set alarm for %d secs", secs_left);
alarm(secs_left);
dolongjmp = 1;
pause();
} else {
switch(val) {
case SIGINT:
case SIGTERM:
case SIGQUIT:
case SIGABRT:
errlog(LOG_INFO,
"received signal to exit (%d)", val);
ssh_kill();
return P_EXIT;
break;
case SIGALRM:
if (exceeded_lifetime()) {
ssh_kill();
return P_EXIT;
}
if (writep && sock != -1 &&
!conn_test(sock, mhost, writep)) {
errlog(LOG_INFO,
"port down, restarting ssh");
ssh_kill();
return P_RESTART;
}
#ifdef TOUCH_PIDFILE
/*
* utimes() with a NULL time argument sets
* file access and modification times to
* the current time
*/
if (pid_file_name &&
utimes(pid_file_name, NULL) != 0) {
errlog(LOG_ERR,
"could not touch pid file: %s",
strerror(errno));
}
#endif
break;
default:
break;
}
}
}
}
/*
* Checks to see if we have exceeded our time to live
* Returns 1 if we have, 0 if we haven't
*/
int
exceeded_lifetime(void)
{
time_t now;
if (max_lifetime > 0 ) {
time(&now);
if (difftime(now, pid_start_time) >= max_lifetime ) {
errlog(LOG_INFO,
"exceeded maximum time to live, shutting down");
return 1;
}
}
return 0;
}
/*
* Wait on child: with options == WNOHANG, poll for
* dead child, else if options == 0, then wait for
* known dead child.
*
* If child was deliberately killed (TERM, INT, KILL),
* or if child called exit(0) or _exit(0), then pass
* message on return to give up (P_EXIT). Otherwise death
* was unnatural (or unintended), and pass message back
* to restart (P_RESTART).
*
* However, if child died with exit(1) on first try, then
* there is some startup error (anything from network
* connection to authentication failure), so we exit.
* If on a restart, however, we keep trying as it must
* have worked once. This doesn't necessarily work if
* the user did an interactive authentication, and then
* isn't there on the restart to enter his password....
* But we can only know very little about what's going
* on inside ssh.
*
* This is further complicated by the behaviour of
* OpenSSH when sent SIGTERM (15). It is possible to
* kill it before it installs the handler for that
* signal, in which case it autossh behaves as above
* and exits. But, in at least interactive use, it
* appears that once the session is established ssh
* installs a handler, and then when signalled (killed)
* it exits with status 255. autossh does not know
* it (ssh) was signalled, so restarts it.
*
*/
int
ssh_wait(int options) {
int status;
int evalue;
time_t now;
if (waitpid(cchild, &status, options) > 0) {
if (WIFSIGNALED(status)) {
switch(WTERMSIG(status)) {
case SIGINT:
case SIGTERM:
case SIGKILL:
/* someone meant it */
errlog(LOG_INFO,
"ssh exited on signal %d; parent exiting",
WTERMSIG(status));
return P_EXIT;
break;
default:
/* continue on and restart */
errlog(LOG_INFO,
"ssh exited on signal %d, restarting ssh",
WTERMSIG(status));
return P_RESTART;
break;
}
} else if (WIFEXITED(status)) {
evalue = WEXITSTATUS(status);
if (start_count == 1 && gate_time != 0) {
/*
* If ssh exits too quickly, give up.
*/
time(&now);
if (difftime(now, start_time) <= gate_time) {
errlog(LOG_ERR,
"ssh exited prematurely "
"with status %d; %s exiting",
evalue, __progname);
return P_EXIT;
}
}
switch(evalue) {
case 255:
/*
* we can get this on an initial
* connection if the connection itself
* is ok, but authentication fails.
* But there's no way to do this nicely:
* we don't have enough info from the
* ssh session and we get the same exit
* status from a dropped connection.
* Hence the gate_time above.
*/
errlog(LOG_INFO,
"ssh exited with error "
"status %d; restarting ssh",
evalue);
return P_RESTART;
break;
case 1:
/*
* the first time, it could be any of
* a number of errors; so we exit and let
* the user fix. But if been running ok
* already, then network may be down and
* then ssh fails exit(1) on the attempt
* to reconnect....so we try to restart.
*/
if (start_count > 1 || gate_time == 0) {
errlog(LOG_INFO,
"ssh exited with error "
"status %d; restarting ssh",
evalue);
return P_RESTART;
}
/* FALLTHROUGH */
case 0: /* exited on success */
#if defined(__CYGWIN__)
if (ntservice)
return P_RESTART;
/* FALLTHROUGH */
#endif