//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;