findgateway.php

<?php
header("Content-Type: application/json; charset=utf-8");

$broadcast_string="SEARCH HCGW";
$port = 49880;
$timeout = array('sec'=>1,'usec'=>500000);

if(!($socket = socket_create(AF_INET, SOCK_DGRAM, SOL_UDP))) {
    $errorcode = socket_last_error();
    $errormsg = socket_strerror($errorcode);
     
    die('{"ERROR":{"ERRORCODE":'.json_encode($errorcode).',"ERRORMSG":'.json_encode($errormsg).'}}');
}

socket_set_option($socket, SOL_SOCKET, SO_BROADCAST, 1); 
socket_sendto($socket, $broadcast_string, strlen($broadcast_string), 0, '255.255.255.255', $port);

socket_set_option($socket,SOL_SOCKET,SO_RCVTIMEO,$timeout);

$from_recv = '';
$port_recv = 0;
$hcgw = array();
$id=1;

while($len = @socket_recvfrom($socket, $buf, 255, 0, $from_recv, $port_recv)) {
    if("HCGW" == substr($buf, 0 , 4)) {
        $dataString = explode("HCGW:",$buf);
        for ($cnt=0;$cnt < count($dataString);$cnt++) {
            if ($dataString[$cnt] != "") {
                $data = array();
                $data['ID'] = $id;
                $data['STATUS'] = 'OK';
                foreach (explode(";", $dataString[$cnt]) as $keyValuePair) {
                    if(!$keyValuePair) continue;
                    list ($key, $value) = explode(':', $keyValuePair, 2);
                    $data[$key] = $value;
                }
                $data['PORT'] = $port;
                $hcgw["HCGW".$id] = $data; 
            }
        }
    $id++;
    }
}

if (empty($hcgw)) {
    $hcgw["HCGW".$id] = array('ID' => $id, 'STATUS' => 'NOT FOUND');
}
echo json_encode($hcgw);
socket_close($socket); 
?>