#!/bin/bash
#
# Copyright (c) 2012 The Chromium OS Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

set -e

# Only run this script on test machines that run in the lab.
# See autotest/server/hosts/site_host.py for more information.
if [ ! -f /mnt/stateful_partition/.labmachine ]; then
  exit 0
fi

NON_ETHERNET_DRIVERS="cdc_ether"

# Critical messages should be sent to /var/log/messages.  Other messages should
# be sent via echo to be harvested by recover_duts.py.
#
# TODO(tbroch) Relocate this to common hook library if/when there's more than
# one hook.
critical_msg() {
  logger -t "$(basename $0)" -- "$@"
}

# Returns the default gateway.
get_default_gateway() {
  local ip_route="$(ip route get 1.0.0.0)"
  echo ${ip_route} | head -n 1 | cut -f 3 -d ' '
}

# Returns 0 if $1 is a non-Ethernet driver, or 1 otherwise.
is_non_ethernet_driver() {
  local driver="$1"
  local non_ethernet_driver

  for non_ethernet_driver in ${NON_ETHERNET_DRIVERS}; do
    if [ "${driver}" = "${non_ethernet_driver}" ]; then
      return 0
    fi
  done
  return 1
}

# Shows the list of Ethernet interfaces found on the system.
find_ethernet_interfaces() {
  local device_path
  local driver_path
  local driver

  for device_path in /sys/class/net/eth*; do
    driver_path="${device_path}/device/driver"
    if [ -e "${driver_path}" ]; then
      driver=$(basename $(readlink -f "${driver_path}"))
      if ! is_non_ethernet_driver "${driver}"; then
        basename "${device_path}"
      fi
    fi
  done
}

# Pings the given ipaddress through all wired ethernet devices
# $1 - IP address to ping.
do_ping() {
  local ip_addr=$1
  for eth in $(find_ethernet_interfaces); do
    ping -q -I ${eth} -c 9 ${ip_addr} && return 0
  done
  return 1
}

# Restart all our ethernet devices and restart shill.
recover_ethernet_devices() {
  local eth
  critical_msg "Gateway still unreachable; restarting ethernet interfaces"
  for eth in $(find_ethernet_interfaces); do
    echo "Bounce interface ${eth}"
    ifconfig ${eth} down
    ifconfig ${eth} up
  done
  initctl stop shill || echo "Shill was not running."
  initctl start shill
  sleep 30
  ifconfig -a
}

# Return the remote IP address of the first established SSH connection
find_ssh_client() {
  netstat -lanp | awk '/tcp.*:22.*ESTABLISHED.*/ {split($5,a,":"); print a[1]}'
}

# Try to find a connected SSH client (our autotest server) and ping it
ping_controlling_server() {
  local default_gateway="$(get_default_gateway)" || default_gateway=
  if [ -n "${default_gateway}" ]; then
    do_ping ${default_gateway} && return 0
  fi

  local ssh_client="$(find_ssh_client)" || ssh_client=
  if [ -n "${ssh_client}" ]; then
    do_ping ${ssh_client} && return 0
  fi
  return 1
}

main() {
  # Attempt to ping our controlling autotest server over ethernet. We guarantee
  # a minimum of 12 minutes network timeout tolerance for tests that disrupt
  # connectivity with the SSH connection from the autotest server. This timeout
  # is 15 minutes to make sure it can never fail before that SSH session does.
  if ping_controlling_server; then
    return 0
  fi
  critical_msg "Gateway unreachable; will retry for 15 minutes"
  for i in {1..30}; do
    sleep 30
    if ping_controlling_server; then
      critical_msg "Gateway now answering; returning success"
      return 0
    fi
  done

  # We can't reach our controlling server through any ethernet devices.
  recover_ethernet_devices

  # Attempt to ping again. If successful, return 1 so that way log the fact
  # that we need to take action to recover the dut.
  if ping_controlling_server; then
    return 1
  fi

  # Last chance - reboot if we can't get any connectivity.
  critical_msg "All efforts to recover ethernet have been exhausted. Rebooting."
  sync
  (sleep 5 && reboot) &
  return 1
}

main