#!/bin/sh
#
# 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"

# 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 the given ethernet device.
# $1 - The ethernet device to ping through.
# $2 - IP address to ping.
do_ping() {
  local eth=$1
  local ip_addr=$2
  ping -I ${eth} -c 1 ${ip_addr}
}

# Restart all our ethernet devices and restart shill.
recover_ethernet_devices() {
  local eth
  for eth in $(find_ethernet_interfaces); do
    ifconfig ${eth} down
    ifconfig ${eth} up
  done
  initctl stop flimflam || echo "Flimflam was not running."
  initctl start flimflam
  sleep 5
}

# Loop through all ethernet devices and see if we can connect to our default
# gateway.
ping_default_gateway_over_ethernet() {
  local eth default_gateway
  default_gateway="$(get_default_gateway)" || default_gateway=
  if [ -n "${default_gateway}" ]; then
    for eth in $(find_ethernet_interfaces); do
      if do_ping ${eth} ${default_gateway}; then
        return 0
      fi
    done
  fi
  return 1
}

main() {
  # Attempt to ping our default gateway over ethernet.
  if ping_default_gateway_over_ethernet; then
    return 0
  fi

  # We can't reach our default gateway 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_default_gateway_over_ethernet; then
    return 1
  fi

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

main