#!/bin/bash
#
# local-ssh-tunnel - sets up and maintains an SSH port-forwarding tunnel
#
# FIXME needs more testing
# killing remote ssh process does not produce expected results

set -e

NAME=local-ssh-tunnel
DESC="Secure port-forwarding tunnel"
LOGGER="logger -t $NAME"
PIDFILE_CONTROL=/var/run/$NAME.control.pid
PIDFILE_SSH=/var/run/$NAME.ssh.pid

# Set defaults
REMOTE_USER=nturner
REMOTE_HOST=codeine.cancerprev.org
TUNNELS="-L 10143:localhost:143 -L 10025:localhost:25"
SSH_OPTS="-g -2 -o ProtocolKeepAlives=300"
SSH_IDENT="/etc/$NAME/.ssh/id_rsa"

# Read config
if [ -f /etc/default/local-ssh-tunnel ]; then
    . /etc/default/local-ssh-tunnel
fi

# Run
case "$1" in
    start)
        if [ -e "$PIDFILE_CONTROL" ] \
                && kill -0 `cat "$PIDFILE_CONTROL"` 2>/dev/null; then
            echo "$NAME already running." 1>&2
            exit 1
        fi
        echo -n "Starting $DESC: "
        (
            (
                echo "starting up."
                while true; do
                    ssh -i "$SSH_IDENT" -l $REMOTE_USER \
                        $SSH_OPTS $TUNNELS $REMOTE_HOST -N &
                    # XXX replace -N with sleep 5 to test failover XXX
                    ssh_pid=$!
                    echo $ssh_pid > "$PIDFILE_SSH"
                    echo "connected. [$ssh_pid]"
                    wait $ssh_pid
                    echo "disconnected [$ssh_pid]; reconnecting in 1 second..."
                    sleep 1
                done
            ) &
            echo $! > "$PIDFILE_CONTROL"
            wait $!
        ) 2>&1 | $LOGGER &
        echo "cdp-tunnel."
        ;;
    stop)
        if [ ! -e "$PIDFILE_CONTROL" -a ! -e "$PIDFILE_SSH" ]; then
            echo "$NAME not running." 1>&2
            exit 1
        fi
        echo -n "Stopping $DESC:"
        echo "shutting down." | $LOGGER
        if [ -e "$PIDFILE_CONTROL" ]; then
            if kill -0 `cat "$PIDFILE_CONTROL"` 2>/dev/null; then
                kill -HUP `cat "$PIDFILE_CONTROL"` 2>/dev/null
                echo -n " control"
            fi
            rm "$PIDFILE_CONTROL"
        fi
        if [ -e "$PIDFILE_SSH" ]; then
            if kill -0 `cat "$PIDFILE_SSH"` 2>/dev/null; then
                kill -HUP `cat "$PIDFILE_SSH"` 2>/dev/null
                echo -n " ssh"
            fi
            rm "$PIDFILE_SSH"
        fi
        echo "."
        ;;
    restart|force-reload)
        $0 stop || true
        $0 start
        ;;
    *)
        echo "ERROR: (FIXME need better feedback)"
        exit 2
        ;;
esac