#!/bin/bash

## Tunnel ssh over an XMPP MUC
##
## Server (system with access to the SSH and XMPP server):
##
##  # ssh-over-xmpp server <conference> <IP address> <port>
##  ssh-over-xmpp server sshxmpp 1.2.3.4 22
##
## Client (system with access to the XMPP server):
##
##  ssh -o ProxyCommand="ssh-over-xmpp client sshxmpp" 127.0.0.1
##

set -o errexit
set -o nounset
set -o pipefail

if [ "$DEBUG" ]; then
  set -x
fi

PROGNAME=$0
TMPDIR=$(mktemp -d)
out=$TMPDIR/out

atexit() {
  rm -rf "$TMPDIR"
}

decode() {
  # shellcheck disable=SC2034
  while IFS=: read stanza type from to body; do
    case "$stanza" in
      m) printf '%b' "${body//%/\\x}" ;;
      *) ;;
    esac
  done
}

server() {
  CONNECT=0
  xmppipe -e -r server -o "$1" -b 1024 -x </dev/null |
    while IFS=: read stanza rest; do
      case "$stanza" in
        p)
          CONNECT=$((CONNECT + 1))
          if [ "$CONNECT" -gt "1" ]; then
            # shellcheck disable=SC2068
            exec "$PROGNAME" session $@
          fi
          ;;
        *) ;;
      esac
    done >/dev/null
}

session() {
  mkdir -p "$TMPDIR"
  trap atexit 0

  mkfifo "$out"

  nc "$2" "$3" <"$out" |
    xmppipe -P 100 -r session -o "$1" -x -s |
    decode >"$out"
}

client() {
  xmppipe -P 100 -r client -o "$1" -x -s | decode
}

# shellcheck disable=SC2068
$@