Why does TCP work, when UDP does not? - php

Question

The code:
<?php
error_reporting(E_ALL);
/* Allow the script to hang around waiting for connections. */
set_time_limit(0);
/* Turn on implicit output flushing so we see what we're getting
* as it comes in. */
ob_implicit_flush();
$address = '127.0.0.1';
$port = 11100;
if (($sock = socket_create(AF_INET, SOCK_DGRAM, SOL_UP)) === false) {
echo "socket_create() failed: reason: " . socket_strerror(socket_last_error()) . "\n";
}
if (socket_bind($sock, $address, $port) === false) {
echo "socket_bind() failed: reason: " . socket_strerror(socket_last_error($sock)) . "\n";
}
if (socket_listen($sock, 5) === false) {
echo "socket_listen() failed: reason: " . socket_strerror(socket_last_error($sock)) . "\n";
}
do {
if (($msgsock = socket_accept($sock)) === false) {
echo "socket_accept() failed: reason: " . socket_strerror(socket_last_error($sock)) . "\n";
break;
}
do {
$out = socket_read($msgsock, 2048);
if (!empty($out)) {
if ($out == 'quit') {
break;
}
elseif ($out == 'shutdown') {
socket_write($msgsock, 'plc down', 8);
socket_close($msgsock);
break 2;
}
else {
switch ($out) {
case "KABBE": $response = "Kabbe te!"; break;
case "SZOPJ": $response = "Szopjal te!"; break;
default: $response = "Ismeretlen parancs";
}
socket_write($msgsock, $response, strlen($response));
break;
}
}
} while (true);
socket_close($msgsock);
} while (true);
socket_close($sock);
?>
It works with TCP:
$socket = socket_create(AF_INET, SOCK_STREAM, SOL_TCP);
but with UDP it's not working:
$sock = socket_create(AF_INET, SOCK_DGRAM, SOL_UDP);
The errors:
Warning: socket_listen() [function.socket-listen]: unable to listen on socket [0]: The attempted operation is not supported for the type of object referenced. in C:\wamp\www\socket\socket.php on line 22
socket_listen() failed: reason: The attempted operation is not supported for the type of object referenced.
Warning: socket_accept() [function.socket-accept]: unable to accept incoming connection [0]: The attempted operation is not supported for the type of object referenced. in C:\wamp\www\socket\socket.php on line 27
socket_accept() failed: reason: The attempted operation is not supported for the type of object referenced.

Answer 1

Because TCP is connection oriented and UDP is not, and there are different APIs for UDP sockets. Have a look at socket_recvfrom and socket_sendto.

Answer 2

I've fixed it by editing Growl class from
socket_sendto($sck, $data, strlen($data), 0x100, $this->address, $this->port);
to
socket_sendto($sck, $data, strlen($data), 0x0, $this->address, $this->port);