#! /bin/bash
# This script can be run by any user with permissions to control the wifi
# interface - however, if it is run as a cron job it will require root
# permissions to re-enable a disabled WiFi radio.  It has been tested 
# succesfully with the following use cases:
# WiFi disabled (nmcli radio wifi off)
# Network device disabled, but WiFi enabled (nmcli dev dis ifname)
# Ethernet connection down (nmcli con down conn_name)
#
# Besides testing with nmcli, connectivity is confirmed with a wget spider
# command to a well known highly available web server (e.g., google.com)
# We do not use icmp/ping to do connectivity testing; this may be 
# prohibited in some environments and would always fail.
# It is not necessary to restart the network service; operations are 
# limited to just the WiFi connection.
#
# This script logs to the systemd journal with systemd-cat, and you can 
# see the entries with "journalctl -t script_name"
# You can see the latest entries first by using "-r", or you
# can have "follow" functionality with "-f"
# Finally, you can see all messages since last boot with "--boot"
# Example:  journalctl -rt wifi-check --boot
#
# Best to call this script as a cron job, with something like 20 minute
# granularity, depending on how unstable your wifi connection is.
# Example crontab entry:
# */20 * * * * /path/to/script
# 
# Finally, this script will not fix network connectivity issues that 
# originate outside of this machine. But you already knew this.


device="wlp3s0"			# device name, e.g., wlp[bus #]s[slot #]
conn="My_SSID"			# connection name often matches WiFi SSID
test_target="google.com"	# choose something with high availability
hostname=$(uname -n)
script=$(basename $0)
DO_RECOVERY=0

# try to get an http response from a well known HA server
# We use "--spider" to avoid actually bringing down content, because
# all we really need is a success response like HTTP 200
online_test() {
	wget -q --tries=10 --timeout=20 --spider http://${test_target}
}

online_test
if [ $? -eq 0 ]; then
	echo "$hostname wifi is connected" | systemd-cat -t $script -p info
else 
	echo "$hostname may be offline: wget failed" | systemd-cat -t $script -p alert
	DO_RECOVERY=1
fi

# Network Manager device status codes 
# GENERAL.STATE:10 (unmanaged) ==> we should never see this
# GENERAL.STATE:20 (unavailable) ==> wifi probably disabled
# GENERAL.STATE:30 (disconnected) ==> wifi enabled, but conn down
# GENERAL.STATE:100 (connected)
device_test() {
  nmcli_out=$(nmcli -t -f GENERAL.STATE device show $device)
  rgx="GENERAL.STATE\:([0-9]+)"
  [[ $nmcli_out =~ $rgx ]]
  return "${BASH_REMATCH[1]}"	
}

# network connection state; $con_state -eq 0 means not active
conn_test() {
	count=$(nmcli -t -f NAME conn show --active | grep wlp3s0 | wc -l)
	return $count
}

if [[ $DO_RECOVERY -eq 1 ]]; then

# Recovery steps
# 1 - Is WiFi enabled?  If not, then fix it.
# wifi radio state is either enabled or disabled

  wifi_status=$(nmcli r wifi)
  if [[ $wifi_status =~ "disabled" ]]; then
        echo "WiFi is disabled... enabling it now." | systemd-cat -t $script -p info

	nmcli r wifi on  # this one line doesn't work for non-root cron jobs
	sleep 15  # give everything a few seconds to re-connect.

	wifi_status=$(nmcli r wifi)
	if [[ $wifi_status =~ "enabled" ]]; then
		echo "WiFi is successfully enabled in Recovery Phase 1" | systemd-cat -t $script -p info
	else
		echo "ERROR: WiFi was NOT successfully enabled in Recovery Phase 1." | systemd-cat -t $script -p err
	fi

	device_test
	if [[ $? -eq 100 ]]; then
		echo "${device} is available and is connected" | systemd-cat -t $script -p info
	elif [[ $? -eq 30 ]]; then
		echo "${device} is available, but is not connected yet" | systemd-cat -t $script -p info
	elif [[ $? -eq 20 ]]; then
		echo "ERROR: ${device} is not available in Recovery Phase 1" | systemd-cat -t $script -p err
	fi

	conn_test
	if [[ $? > 0 ]]; then
		echo "Connection $conn is up in Recovery Phase 1" | systemd-cat -t $script -p info
	else
		echo "Connection $conn is down, attempting to bring it up" | systemd-cat -t $script -p info
		nmcli c up $conn
		conn_test
		if [ $? > 0 ]; then echo "Success!" | systemd-cat -t $script -p info
		fi
	fi

	online_test
	if [ $? -eq 0 ]; then
		echo "$hostname is back online. Recovery script is finished." | systemd-cat -t $script -p info
		DO_RECOVERY=0		# We're done now.
	else echo "$hostname is still offline in Recovery Phase 1" | systemd-cat -t $script -p info
	fi

  else echo "Phase 1 check: WiFi is enabled" | systemd-cat -t $script -p info

  fi # end wifi_status check

fi  # end DO_RECOVERY Phase 1

# echo "DO_RECOVERY flag is ${DO_RECOVERY} after Phase 1" | systemd-cat -t $script -p debug

# re-using the recovery flag is a bit stupid, but I'm tired.
if [[ $DO_RECOVERY -eq 1 ]]; then

#  echo "In Phase 2 now" | systemd-cat -t $script -p debug

  # 2 - WiFi is enabled, how about the network device?
  device_test
  dev_status=$?
  if [[ $dev_status > 20 ]]; then	# see network device status codes above
	nmcli conn up $conn
	if [[ $? -eq 0 ]]; then 
	  echo "Connection ${conn} is up in Phase 2" | systemd-cat -t $script -p debug
	  online_test
	  if [ $? -eq 0 ]; then
	    echo "$hostname is back online" | systemd-cat -t $script -p info
	  else echo "$hostname is still offline in Phase 2" | systemd-cat -t $script -p debug
	  fi  # end online test
	else 
	  echo "ERROR: Connection ${conn} did not come up in Phase 2" | systemd-cat -t $script -p err
	fi # end conn test
  else
	echo "ERROR: Device status is ${dev_status} - this can't be brought up in Phase 2" | systemd-cat -t $script -p err
  fi
fi # end second round of DO_RECOVERY
exit