#!/bin/sh

# Roughly based on this article:
# https://werat.github.io/2017/02/04/tmux-ssh-agent-forwarding.html

REMOTE_LINK="${HOME}/.ssh/ssh_auth_sock"

if [ "${1:-}" = "force" ] && [ -S "${SSH_AUTH_SOCK}" ] ; then
  ln -sf "${SSH_AUTH_SOCK}" "${REMOTE_LINK}"
  exit 0
fi

if test \! -S "${REMOTE_LINK}" -a -S "${SSH_AUTH_SOCK}" ; then
  ln -sf "${SSH_AUTH_SOCK}" "${REMOTE_LINK}"
fi

# Handle X forwarding, per sshd(8)
if read proto cookie && [ -n "$DISPLAY" ]; then
  if [ `echo $DISPLAY | cut -c1-10` = 'localhost:' ]; then
    # X11UseLocalhost=yes
    echo add unix:`echo $DISPLAY |
      cut -c11-` $proto $cookie
  else
    # X11UseLocalhost=no
    echo add $DISPLAY $proto $cookie
  fi | xauth -q -
fi