#!/bin/sh

# Wrapper around autossh to always keep open ssh and web tunnels
# Usable as cronjob and ifup hook

set -e

DEFAULTS=/etc/local/autoautossh
DAEMON=/usr/bin/autossh

# Set defaults
DEFAULTLOCALUSER=autossh
DEFAULTLOCALIFACE=eth0
DEFAULTREMOTEHOST=defaultserver
DEFAULTREMOTESSHPORT=2200
DEFAULTREMOTEHTTPPORT=2280

# Check for daemon presence
[ -x "$DAEMON" ] || exit 0

# Include config defaults if available
[ -r "$DEFAULTS" ] && . "$DEFAULTS"

# allow overriding these in environment
LOCALUSER=${LOCALUSER:-$DEFAULTLOCALUSER}
LOCALIFACE=${LOCALIFACE:-$DEFAULTLOCALIFACE}
REMOTEHOST=${REMOTEHOST:-$DEFAULTREMOTEHOST}
REMOTESSHPORT=${REMOTESSHPORT:-$DEFAULTREMOTESSHPORT}
REMOTEHTTPPORT=${REMOTEHTTPPORT:-$DEFAULTREMOTEHTTPPORT}


# ifup hack: Ignore ifup'ing irrelevant interfaces (including loopback)
# Unset LOCALIFACE to always continue
[ -z "$LOCALIFACE" ] || [ -z "$IFACE" ] || [ "$IFACE" = eth0 ] || exit 0

# Back out if possible to reach ourselves from outside
! su "$LOCALUSER" -c "ssh '$REMOTEHOST' -- ssh -C -o ConnectTimeout=5 -o ConnectionAttempts=3 -p '$REMOTESSHPORT' localhost -- true" || exit 0

# SSH tunnel is broken - establish fresh tunnels
killall autossh || true
su "$LOCALUSER" -c "autossh -fN -M 0 -o BatchMode=yes -o ServerAliveInterval=60 -o ServerAliveCountMax=3 -R '$REMOTESSHPORT':localhost:22 -R '$REMOTEHTTPPORT':localhost:80 '$REMOTEHOST'" &

exit 0