wifi_check.py

"""
http://www.raspberrypi.org/forums/viewtopic.php?f=28&t=54001
check for the connection to the WIFI router
if it is down, try to reestablish

alternately, can also reboot
"""

import subprocess
WLAN_check_flg = False
router_IP='10.0.1.1'

def WLAN_check(WLAN_check_flg=False):
    '''
    This function checks if the WLAN is still up by pinging the router.
    If there is no return, we'll reset the WLAN connection.
    If the resetting of the WLAN does not work, we need to reset the Pi.

    '''

    ping_ret = subprocess.call(['ping -c 2 -w 1 -q %s |grep "1 received" > /dev/null 2> /dev/null' % router_IP], shell=True)
    if ping_ret:
        # we lost the WLAN connection.
        # did we try a recovery already?
        if WLAN_check_flg:
            # we have a serious problem and need to reboot the Pi to recover the WLAN connection
            subprocess.call(['logger "WLAN Down, Pi is forcing a reboot"'], shell=True)
            WLAN_check_flg = False
            subprocess.call(['sudo reboot'], shell=True)
        else:
            # try to recover the connection by resetting the LAN
            subprocess.call(['logger "WLAN is down, Pi is resetting WLAN connection"'], shell=True)
            subprocess.call(['sudo python /home/pi/raspberrypi_python/turn_on_led.py 0'], shell=True)
            #WLAN_check_flg = True # try to recover
            subprocess.call(['sudo /sbin/ifdown wlan0 && sleep 10 && sudo /sbin/ifup --force wlan0'], shell=True)
    else:
        subprocess.call(['logger "WLAN is up"'], shell=True)
        subprocess.call(['sudo python /home/pi/raspberrypi_python/turn_on_led.py 1'], shell=True)
        WLAN_check_flg = False



WLAN_check(WLAN_check_flg)