Using PHP broadcast to detect Server IP address - php

Question

I want to do something like this article:
broadcast to detect Server IP address
and transfer to PHP, does it possible?
The reason is I want to send broadcast socket to server, and the server will return message then I can determine the message is what I want or not to detect the true IP of the message sender.
The code is like:
<?php
error_reporting(E_ALL);
$address = "255.255.255.255";
$port = 10000;
/* Create a udp socket. */
$socket = socket_create(AF_INET, SOCK_STREAM, SOL_TCP);
if ($socket === false) {
echo "socket_create() failed: reason: " . socket_strerror(socket_last_error()) . "<br/>";
} else {
echo "socket successfully created.<br/>";
}
echo "Attempting to connect to '$address' on port '$port'..."."<br/>";
$result = socket_connect($socket, $address, $port);
if ($result === false) {
echo "socket_connect() failed.\nReason: ($result) " . socket_strerror(socket_last_error($socket)) . "<br/>";
} else {
echo "successfully connected to $address."."<br/>";
}
$i="theMessage";
echo "Sending $i to server."."<br/>";
socket_write($socket, $i, strlen($i));
$input = socket_read($socket, 512);
echo "Response from server is: $input"."<br/>";
$ip="";
if($input=="I want")
$ip=socket_send_from_the_IP; // just psuedocode
echo "Closing socket...";
socket_close($socket);
?>
Or is the direction of my question wrong?
I also think that I should use httprequest?
Any answer appreciated.