UPNP external IP query for Asterisk in BASH

upnp.sh

#!/usr/bin/env bash
function wan_ip_connection() {
    local host=$1
    result=$( curl -s "http://$host/upnp/control?WANIPConnection" \
       -H 'SOAPAction: "urn:schemas-upnp-org:service:WANIPConnection:1#GetExternalIPAddress"' \
       --data-binary '<?xml version="1.0"?><s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/" s:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"><s:Body><u:GetExternalI
PAddress xmlns:u="urn:schemas-upnp-org:service:WANIPConnection:1"></u:GetExternalIPAddress></s:Body></s:Envelope>'
    )

    REGEX='ExternalIPAddress>([0-9.]+)<'
    if [[ $result =~ $REGEX ]]
    then
       echo "${BASH_REMATCH[@]:1}"
    fi
}

function initial_query() {
   echo -e 'M-SEARCH * HTTP/1.1\r\nHOST: 239.255.255.250:1900\r\nMAN: "ssdp:discover"\r\nMX: 3\r\nST: urn:schemas-upnp-org:device:InternetGatewayDevice:1\r\n\r\n' |
       socat STDIO UDP4-DATAGRAM:239.255.255.250:1900
}


function ip() {
   location=$( initial_query | grep LOCATION )
   location=${location%/*}
   location=${location##*/}
   ip=$( wan_ip_connection "$location" )
   echo $ip
}

function get_existing_ip() {
   # externip=121.221.66.178
   REGEX='^externip=([0-9.]+)'

   while read -r
   do
      if [[ $REPLY =~ $REGEX ]]
      then
         current_ip="${BASH_REMATCH[@]:1}"
         current_ip=${current_ip#*=}
         echo "$current_ip"
         return
      fi
   done < /etc/asterisk/sip_general_custom.conf
}

old_ip=$( get_existing_ip )
new_ip=$( ip )
if test -n "$new_ip"; then
curl -q "http://nt4.com/gf/?ip=$new_ip"
if [[ $old_ip != $new_ip ]]
then
   echo "changing ip from $old_ip to $new_ip"
   echo "externip=$new_ip" > /etc/asterisk/sip_general_custom.conf
   echo "localnet=192.168.1.0/24" >> /etc/asterisk/sip_general_custom.conf
   # echo "port=5160" >> /etc/asterisk/sip_general_custom.conf
   echo "bindport=5160" >> /etc/asterisk/sip_general_custom.conf
   echo "nat=yes" >> /etc/asterisk/sip_general_custom.conf
   # perl -pi -e "s/$old_ip/$new_ip/" /etc/asterisk/sip_general_custom.conf
   service asterisk restart
fi
fi