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<source lang=“php”><?php

/* * PHP Multi-Client TCP Socket Example * * * Will listen on a given socket for TCP connections, echoing whatever data * * is sent to that socket. * * * * Original script by KnoB in a comment in the PHP documentation: * * * * * * Heavily modified and commented by Andrew Gillard * */

//What address are we listening on? This will have to be the same as in // the client. You probably just want '' for both. $address = '';

//What port to use? Again, the client will need to know this, too $port = 10000;

?><!DOCTYPE html PUBLIC “-//W3C//DTD XHTML 1.0 Strict//EN” “”> <html xmlns=“”> <head>

<title>PHP Multi-Client Server Example</title>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" />
<style type="text/css">
div.error {
	padding: 0px 10px 5px 10px;
	background-color: #f88;
	border: 1px solid #f00;
div.error span {
	font-family: monospace;

</head> <body>


//Disable PHP's script execution time limit set_time_limit(0);

//Ensure that every time we call “echo”, the data is sent to the browser // IMMEDIATELY, rather than when PHP feels like it ob_implicit_flush();

//Normally when the user clicks the “Stop” button in their browser, the // script is terminated. This line stops that happening, so that we can // detect the Stop button ourselves and properly close our sockets (to // prevent the listening socket remaining open and stealing the port) ignore_user_abort(true);

//Define a function that we can call when any of our socket function calls // fail. This allows us to consolidate our error message XHTML and avoid // code repetition. If $die is set to true, the script will terminate function socketError($errorFunction, $die=false) {

$errMsg = socket_strerror(socket_last_error());

//This odd construct (known as a heredoc) just echos all of the text // between “«<EOHTML” and “EOHTML;”. It's just a neater and easier to read // format than using standard quoted strings. If you want to use one // yourself, bear in mind that the structure is VERY strict: the opening // line must be just “«<” followed by the ending identifier, and the last // line must contain NOTHING except the identifier (“EOHTML” in this case). // The semi-colon after the closing identifier is optional, but it is // important to realise that there cannot even be whitespace (tabs or // spaces) before the EOHTML; at the end!!

echo <<<EOHTML

<div class=“error”> <h1>$errorFunction() failed!</h1> <p>

<strong>Error Message:</strong>

</p> <p>Note that if you have recently pressed your browser's Stop or Refresh/Reload button on this server script, you may have to wait a few seconds for the old server to release its listening port. As such, wait and try again in a few seconds. </p> </div> EOHTML;

if ($die) {

	<nowiki>//</nowiki>Close the BODY and HTML tags as well as terminating script 
	<nowiki>//</nowiki>execution because the die() call prevents us ever getting to the last
	<nowiki>//</nowiki> lines of this script


//Attempt to create our socket. The “@” hides PHP's standard error reporting, // so that we can output our own error message if it fails if (!($server = @socket_create(AF_INET, SOCK_STREAM, SOL_TCP))) {

socketError('socket_create', true);


//Set the “Reuse Address” socket option to enabled socket_set_option($server, SOL_SOCKET, SO_REUSEADDR, 1);

//Attempt to bind our socket to the address and port that we're listening on. // Again, we suppress PHP's error reporting in favour of our own if (!@socket_bind($server, $address, $port)) {

socketError('socket_bind', true);


//Start listening on the address and port that we bound our socket to above, // using our own error reporting code as before if (!@socket_listen($server)) {

socketError('socket_listen', true);


//Create an array to store our sockets in. We use this so that we can // determine which socket has new incoming data with the “socket_select()” // function, and to properly close each socket when the script finishes $allSockets = array($server);

//Start looping indefinitely. On each iteration we will make sure the browser's // “Stop” button hasn't been pressed and, if not, see if we have any incoming // client connection requests or any incoming data on existing clients while (true) {

<nowiki>//</nowiki>We have to echo something to the browser or PHP won't know if the Stop
<nowiki>//</nowiki> button has been pressed
  echo ' ';
  if (connection_aborted()) {
  	<nowiki>//</nowiki>The Stop button has been pressed, so close all our sockets and exit
  	foreach ($allSockets as $socket) {

//Now break out of this while() loop!


//socket_select() is slightly strange. You have to make a copy of the array

<nowiki>//</nowiki> of sockets you pass to it, because it changes that array when it returns
<nowiki>//</nowiki> and the resulting array will only contain sockets with waiting data on
<nowiki>//</nowiki> them. $write and $except are set to NULL because we aren't interested in
<nowiki>//</nowiki> them. The last parameter indicates that socket_select will return after
<nowiki>//</nowiki> that many seconds if no data is receiveed in that time; this prevents the
<nowiki>//</nowiki> script hanging forever at this point (remember, we might want to accept a
<nowiki>//</nowiki> new connection or even exit entirely) and also pauses the script briefly
<nowiki>//</nowiki> to prevent this tight while() loop using a lot of processor time
$changedSockets = $allSockets;
socket_select($changedSockets, $write = NULL, $except = NULL, 5);

//Now we loop over each of the sockets that socket_select() says have new

<nowiki>//</nowiki> data on them
foreach($changedSockets as $socket) {
    if ($socket == $server) {
    	<nowiki>//</nowiki>socket_select() will include our server socket in the
    	<nowiki>//</nowiki> $changedSockets array if there is an incoming connection attempt
    	<nowiki>//</nowiki> on it. This will only accept one incoming connection per while()
    	<nowiki>//</nowiki> loop iteration, but that shouldn't be a problem given the
    	<nowiki>//</nowiki> frequency that we're iterating
        if (!($client = @socket_accept($server))) {
        	<nowiki>//</nowiki>socket_accept() failed for some reason (again, we hid PHP's
        	<nowiki>//</nowiki> standard error message), so let's say what happened...
        	socketError('socket_accept', false);
        } else {
        	<nowiki>//</nowiki>We've accepted the incoming connection, so add the new client
        	<nowiki>//</nowiki> socket to our array of sockets
        	$allSockets[[]] = $client;
    } else {
		<nowiki>//</nowiki>Attempt to read data from this socket
        $data = socket_read($socket, 2048);
        if ($data === false || $data === //) {
          	<nowiki>//</nowiki>socket_read() returned FALSE, meaning that the client has
          	<nowiki>//</nowiki> closed the connection. Therefore we need to remove this
          	<nowiki>//</nowiki> socket from our client sockets array and close the socket
          	<nowiki>//</nowiki>A potential bug in PHP means that socket_read() will return
          	<nowiki>//</nowiki> an empty string instead of FALSE when the connection has
          	<nowiki>//</nowiki> been closed, contrary to what the documentation states. As
          	<nowiki>//</nowiki> such, we look for FALSE or an empty string (an empty string
          	<nowiki>//</nowiki> for the current, buggy, behaviour, and FALSE in case it ends
          	<nowiki>//</nowiki> up getting fixed at some point)
        } else {
          	<nowiki>//</nowiki>We got useful data from socket_read(), so let's echo it.
          	<nowiki>//</nowiki> "$socket" will be output as "Resource id #n", where n is
          	<nowiki>//</nowiki> the internal ID of the socket, e.g. "Resource id #3"
          	<nowiki>//</nowiki>Note also that $data can be an empty string, so we check
          	<nowiki>//</nowiki> for that in our "elseif ($data)" line
			echo "\r\n<p><strong>&middot;</strong> $socket wrote: $data</p>";


//Once we get here, the sockets have been closed, so just echo our XHTML footer


</body> </html></source>

multi-client_tcp_server_example.txt · Last modified: 2014/11/24 01:14 by