#!/usr/bin/env bash
#  SPDX-FileCopyrightText: 2019 Max Mehl <mail [at] mehl [dot] mx>
#  SPDX-License-Identifier: GPL-3.0-or-later
########################################################################
#
#  Reads hosts file and checks SSH access. If not possible with public
#  key, this script tries to place the system's public key on the host
#  via a normal (password-based) SSH access attempt.
#
########################################################################

CURDIR=$(dirname "$(readlink -f "$0")")
if [ ! -e "$CURDIR"/config.cfg ]; then echo "Missing config.cfg file. Edit and rename config.cfg.sample"; exit 1; fi
source "$CURDIR"/config.cfg

if [ ! -e "${HOSTS}" ]; then echo "Missing hosts file. Please set a correct value of HOSTS= in your config file. Current value: ${HOSTS}"; exit 1; fi

if [ -n "${SSH_KEY}" ]; then
  SSH_KEY_ARG="-i ${SSH_KEY}"
else
  # defaults
  SSH_KEY_ARG=""
  SSH_KEY=~/.ssh/id_rsa
fi

ARG1="$1"

function trim {
  sed -r -e 's/^\s*//g' -e 's/\s*$//g'
}

while read -r line; do
  # if line is a comment, go to next line
  if echo "$line" | grep -qE "^\s*#"; then continue; fi

  RHOST=$(echo "$line" | cut -d";" -f1 | trim)

  # Jump to next line if this line's host does not match host of ARG1 (if given)
  if [[ "${ARG1}" != "" ]] && [[ "${ARG1}" != "${RHOST}" ]]; then
    continue
  fi

  # Get SSH port if needed
  if echo "$RHOST" | grep -q ":"; then
    RPORT=$(echo "$RHOST" | cut -d":" -f2)
    RHOST=$(echo "$RHOST" | cut -d":" -f1)
    RPORT_ARG="-p ${RPORT}"
  else
    # defaults
    RPORT=""
    RPORT_ARG=""
  fi

  echo "[INFO] Trying ${RHOST}"

  STATUS=$(ssh -n -o StrictHostKeyChecking=no -o BatchMode=yes -o ConnectTimeout=5 ${RPORT_ARG} ${SSH_KEY_ARG} "${RHOST}" "echo -n"; echo $?)

  if [ $STATUS != 0 ]; then
    echo -n "[ERROR] No SSH login possible for ${RHOST}. "
    if [[ "${ARG1}" != "" ]]; then
      echo "Aborting."
      exit 1
    else
      echo "Adding public key with password: "
      cat "${SSH_KEY}".pub | ssh -o StrictHostKeyChecking=no ${RPORT_ARG} ${SSH_KEY_ARG} "${RHOST}" 'cat >> ~/.ssh/authorized_keys'
    fi
  else
    echo "[SUCCESS] SSH login possible for ${RHOST}."
  fi

done < "$HOSTS"