//服务器信息  
$server = 'udp://127.0.0.1:9998';  
//消息结束符号  
$msg_eof = "\n";  
$socket = stream_socket_server($server, $errno, $errstr, STREAM_SERVER_BIND);  
if (!$socket) {  
    die("$errstr ($errno)");  
}  
  
do {  
    //接收客户端发来的信息  
    $inMsg = stream_socket_recvfrom($socket, 1024, 0, $peer);  
    //服务端打印出相关信息  
    echo "Client : $peer\n";  
    echo "Receive : {$inMsg}";  
    //给客户端发送信息  
    $outMsg = substr($inMsg, 0, (strrpos($inMsg, $msg_eof))).' -- '.date("D M j H:i:s Y\r\n");  
    stream_socket_sendto($socket, $outMsg, 0, $peer);  
      
} while ($inMsg !== false); 

function udpGet($sendMsg = '', $ip = '127.0.0.1', $port = '9998'){
	$handle = stream_socket_client("udp://{$ip}:{$port}", $errno, $errstr);
	if( !$handle ){
		die("ERROR: {$errno} - {$errstr}\n");
	}
	fwrite($handle, $sendMsg."\n");
	$result = fread($handle, 1024);
	fclose($handle);
	return $result;
}

$result = udpGet('Hello World');
echo $result;