win-gpg-agent-relay

win-gpg-agent-relay.sh

#!/usr/bin/env bash

GNUPGHOME="$HOME/.gnupg"
PIDFILE="$GNUPGHOME/win-gpg-agent-relay.pid"
LOGFILE="$GNUPGHOME/win-gpg-agent-relay.log"

is_pid_running() {
  if [[ -z "$1" ]]; then
    return 1
  fi
  ps -p "$1" >/dev/null
  return $?
}

# Log only if verbose mode is active
log() {
  if [[ -n "$VERBOSE" ]]; then
    # shellcheck disable=SC2068
    echo >&2 "$@"
  fi
}
# Log
info() {
  # shellcheck disable=SC2068
  echo >&2 "$@"
}

_cleanup() {
  info "Cleaning up relay to $GNUPGHOME/S.gpg-agent..."
  if is_pid_running "$SOCAT_GPG_AGENT_PID"; then
    kill -SIGTERM "$SOCAT_GPG_AGENT_PID" || info "Failed."
  fi

  info "Cleaning up relay to $GNUPGHOME/S.gpg-agent.ssh..."
  if is_pid_running "$SOCAT_GPG_AGENT_SSH_PID"; then
    kill -SIGTERM "$SOCAT_GPG_AGENT_SSH_PID" || info "Failed."
  fi
}

die() {
  if [[ -n "$1" ]]; then
    info "$1"
  fi
  info "Exiting."
  exit 1
}

usage() {
  info "Usage: win-gpg-agent-relay [OPTIONS] COMMAND"
  info ""
  info "  SUMMARY: Relay local GPG sockets to win-gpg-agent's ones in order to integrate WSL2 and host."
  info ""
  info "  OPTIONS:"
  info "    -h|--help     this page"
  info ""
  info "    -v|--verbose  verbose mode"
  info ""
  info "    --wingpgagent-sockets-windir DIR  Directory where win-gpg-agent store its sockets."
  info "                                     This is a the directory from windows host. ex: 'C:\win-gpg-agent-sockets'"
  info ""
  info "    --wingpgagent-dir DIR            Directory where win-gpg-agent is."
  info ""
  info "  COMMAND: start, stop foreground"
}

fg_opts() {
  FG_OPTS=()
  # Generate opts for passing it to foreground version
  if [[ -n "$VERBOSE" ]]; then
    FG_OPTS+=("-v")
  fi
  if [[ -n "$WINGPGAGENT_SOCKETS_WINDIR" ]]; then
    # shellcheck disable=SC2089
    FG_OPTS+=("--wingpgagent-sockets-windir")
    FG_OPTS+=("$WINGPGAGENT_SOCKETS_WINDIR")
  fi
  if [[ -n "$WINGPGAGENT_DIR" ]]; then
    FG_OPTS+=("--wingpgagent-dir")
    FG_OPTS+=("$WINGPGAGENT_DIR")
  fi
}

main() {

  POSITIONAL=()
  VERBOSE=""
  while (($# > 0)); do
    case "$1" in
    -v | --verbose)
      VERBOSE="ENABLED"
      shift # shift once since flags have no values
      ;;

    -h | --help)
      usage
      exit 0
      ;;

    --wingpgagent-sockets-windir)
      numOfArgs=1
      if (($# < numOfArgs + 1)); then
        shift $#
      else
        WINGPGAGENT_SOCKETS_WINDIR="$2"
        shift $((numOfArgs + 1))
      fi
      ;;

    --wingpgagent-dir)
      numOfArgs=1
      if (($# < numOfArgs + 1)); then
        shift $#
      else
        WINGPGAGENT_DIR="$2"
        shift $((numOfArgs + 1))
      fi
      ;;

    *) # unknown flag/switch
      POSITIONAL+=("$1")
      shift
      if [[ "${#POSITIONAL[@]}" -gt 1 ]]; then
        usage
        die
      fi
      ;;
    esac
  done

  set -- "${POSITIONAL[@]}" # restore positional params

  case "${POSITIONAL[0]}" in
  start)
    fg_opts
    true >"$LOGFILE"
    # shellcheck disable=SC2086,SC2090
    start-stop-daemon \
      --start --oknodo \
      --pidfile "$PIDFILE" -m \
      --output "$LOGFILE" \
      --background \
      --name bash --startas "$0" ${VERBOSE:+--verbose} -- foreground "${FG_OPTS[@]}"
    ;;

  stop)
    start-stop-daemon --pidfile "$PIDFILE" --stop --remove-pidfile ${VERBOSE:+--verbose}
    ;;

  status)
    start-stop-daemon --pidfile "$PIDFILE" --status ${VERBOSE:+--verbose}
    local result=$?
    case $result in
    0) info "$0 is running" ;;
    1 | 3) info "$0 is not running" ;;
    4) info "$0 unable to determine status" ;;
    esac
    return $result
    ;;

  foreground)
    relay
    ;;

  *)
    usage
    die
    ;;
  esac
}

mult_by_two_and_max() {
  # outputs max(x * 2, y) 
  # where x is first argument, y the second one
  local max
  max=${2:-600}
  last=${1:-1}
  
  curr=$((last * 2))
  curr=$((curr > max ? max : curr))
  echo "$curr"
}

sorelay() {
  # Serve socket at path $1 relaying to windows AF_LINUX socket $2 through sorelay tool
  # return 0 on successfully setup socat, outputs the PID
  info "Set up $1 as socket relaying to $2"

  local pid
  local exec
  exec="\'$SORELAY_BIN\' \'$2\'"
  socat UNIX-LISTEN:"\"$1\"",fork EXEC:"\"$exec\"",nofork 1>/dev/null 2>&1 &
  pid="$!"

  # quickly check if socat still running to catch early errors
  if ! is_pid_running "$pid"; then
    info "socat $1 failed"
    return 1
  fi

  echo "$pid"
}

relay() {

  trap _cleanup EXIT

  log "Verbose mode: ON"
  log "Using win-gpg-agent: $WINGPGAGENT_DIR"
  log "Using win-gpg-agent sockets in: $WINGPGAGENT_SOCKETS_WINDIR"

  [[ -z "$WINGPGAGENT_SOCKETS_WINDIR" ]] && usage && die "Please provide directory of win-gpg-agent sockets"
  [[ -z "$WINGPGAGENT_DIR" ]] && usage && die "Please provide directory of win-gpg-agent"

  TMPFOLDER=$(mktemp -d)
  { [[ -z "$TMPFOLDER" ]] && die "Failed creating a temp folder"; } || log "Temp folder: $TMPFOLDER"
  cp "$WINGPGAGENT_DIR/sorelay.exe" "$TMPFOLDER/sorelay.exe" || die "Failed to copy sorelay."

  SORELAY_BIN="$TMPFOLDER/sorelay.exe"
  GPG_AGENT_SOCK="$WINGPGAGENT_SOCKETS_WINDIR/S.gpg-agent"
  GPG_AGENT_SSH_SOCK="$WINGPGAGENT_SOCKETS_WINDIR/S.gpg-agent.ssh"

  info "Killing previously setup gpg agent..."
  echo "KILLAGENT" | gpg-connect-agent >/dev/null 2>&1

  if ! SOCAT_GPG_AGENT_PID=$(sorelay "$HOME/.gnupg/S.gpg-agent" "$GPG_AGENT_SOCK"); then die; fi
  info "socat running with PID: $SOCAT_GPG_AGENT_PID"
  if ! SOCAT_GPG_AGENT_SSH_PID=$(sorelay "$HOME/.gnupg/S.gpg-agent.ssh" "$GPG_AGENT_SSH_SOCK"); then die; fi
  info "socat running with PID: $SOCAT_GPG_AGENT_SSH_PID"

  while true; do
    log -n "Polling GPG agent... "
    gpg-connect-agent /bye >/dev/null 2>&1 || die "Failure communicating with S.gpg-agent."
    log "OK"
    log -n "Polling SSH agent..."
    ssh-add -L >/dev/null 2>&1 || die "Failure communicating with S.gpg-agent.ssh."
    log "OK"

    local time_s
    time_s=$(mult_by_two_and_max "${time_s:-5}" 600)
    log "Wait $time_s seconds"
    sleep "$time_s"
  done
}

main "$@"