#!/usr/bin/env python
"""This starts an SSH tunnel to a given host.
If the SSH process ever dies then this script will detect that and restart it.
I use this under Cygwin to keep open encrypted tunnels to
port 25 (SMTP), port 143 (IMAP4), and port 110 (POP3). I set my mail client to talk to
localhost and I keep this script running in the background.

Note that this is a rather stupid script at the moment because it
just looks to see if any ssh process is running. It should really
make sure that our specific ssh process is running.
ssh is missing a very useful feature. It has no way to report the
process id of the background daemon that it creates with the -f command.
This would be a really useful script if I could figure a way around this problem.
"""
import pexpect
import getpass
import time

# SMTP:25 IMAP4:143 POP3:110
tunnel_command = 'ssh -C -N -f -L 25:127.0.0.1:25 -L 143:127.0.0.1:143 -L 110:127.0.0.1:110 %(user)@%(host)'
host = raw_input('Hostname: ')
user = raw_input('Username: ')
X = getpass.getpass('Password: ')

def get_process_info ():
    # This seems to work on both Linux and BSD, but should otherwise be considered highly UNportable.
    ps = pexpect.run ('ps ax -O ppid')
    pass
def start_tunnel ():
    try:
        ssh_tunnel = pexpect.spawn (tunnel_command % globals())
        ssh_tunnel.expect ('password:')
        time.sleep (0.1)
        ssh_tunnel.sendline (X)
        time.sleep (60) # Cygwin is slow to update process status.
        ssh_tunnel.expect (pexpect.EOF)

    except Exception, e:
        print str(e)

def main ():
    while 1:
        ps = pexpect.spawn ('ps')
        time.sleep (1)
        index = ps.expect (['/usr/bin/ssh', pexpect.EOF, pexpect.TIMEOUT])
        if index == 2:
            print 'TIMEOUT in ps command...'
            print str(ps)
            time.sleep (13)
        if index == 1:
            print time.asctime(),
            print 'restarting tunnel'
            start_tunnel ()
            time.sleep (11)
	        print 'tunnel OK'
        else:
            # print 'tunnel OK'
            time.sleep (7)

if __name__ == '__main__':
    main ()

# This was for older SSH versions that didn't have -f option
#tunnel_command = 'ssh -C -n -L 25:%(host)s:25 -L 110:%(host)s:110 %(user)s@%(host)s -f nothing.sh'
#nothing_script = """#!/bin/sh
#while true; do sleep 53; done
#"""

