1Jul/109
How to create a socket server in PHP
EDIT: If you need to submit bugs or want to improve my work, its now available on github!
Ever tried searching for information on how to properly create a multi-client socket server in PHP? You’ll get plenty of results with outdated and messy source code, some of which won’t even work.
This was the my state a couple days ago when I decided that I wanted to build an IRC server. The why is not important… (For the fun of building an IRC Server). So I googled around a hell of a lot bit until I finally found some code that worked on its own, and quickly built a semi-functional IRC server using it, and headed off to sleep at 5am.
The next day I was very, very happy with the results of my hard labor, but it wasn’t good enough, so I started re-writing it from scratch as an Object, and thus I created class::IRCServer.
Today, once I felt that I was finished screwing around with my newly built IRCd, I decided to modify the function enough to be used on its own as a socket server, to share with the world.
And thus, class::SocketServer was created.
< ?php /*! @class SocketServer @author Navarr Barnier @abstract A Framework for creating a multi-client server using the PHP language. */ class SocketServer { /*! @var config @abstract Array - an array of configuration information used by the server. */ protected $config; /*! @var hooks @abstract Array - a dictionary of hooks and the callbacks attached to them. */ protected $hooks; /*! @var master_socket @abstract resource - The master socket used by the server. */ protected $master_socket; /*! @var max_clients @abstract unsigned int - The maximum number of clients allowed to connect. */ public $max_clients = 10; /*! @var max_read @abstract unsigned int - The maximum number of bytes to read from a socket at a single time. */ public $max_read = 1024; /*! @var clients @abstract Array - an array of connected clients. */ public $clients; /*! @function __construct @abstract Creates the socket and starts listening to it. @param string - IP Address to bind to, NULL for default. @param int - Port to bind to @result void */ public function __construct($bind_ip,$port) { set_time_limit(0); $this->hooks = array(); $this->config["ip"] = $bind_ip; $this->config["port"] = $port; $this->master_socket = socket_create(AF_INET, SOCK_STREAM, 0); socket_bind($this->master_socket,$this->config["ip"],$this->config["port"]) or die("Issue Binding"); socket_getsockname($this->master_socket,$bind_ip,$port); socket_listen($this->master_socket); SocketServer::debug("Listenting for connections on {$bind_ip}:{$port}"); } /*! @function hook @abstract Adds a function to be called whenever a certain action happens. Can be extended in your implementation. @param string - Command @param callback- Function to Call. @see unhook @see trigger_hooks @result void */ public function hook($command,$function) { $command = strtoupper($command); if(!isset($this->hooks[$command])) { $this->hooks[$command] = array(); } $k = array_search($function,$this->hooks[$command]); if($k === FALSE) { $this->hooks[$command][] = $function; } } /*! @function unhook @abstract Deletes a function from the call list for a certain action. Can be extended in your implementation. @param string - Command @param callback- Function to Delete from Call List @see hook @see trigger_hooks @result void */ public function unhook($command = NULL,$function) { $command = strtoupper($command); if($command !== NULL) { $k = array_search($function,$this->hooks[$command]); if($k !== FALSE) { unset($this->hooks[$command][$k]); } } else { $k = array_search($this->user_funcs,$function); if($k !== FALSE) { unset($this->user_funcs[$k]); } } } /*! @function loop_once @abstract Runs the class's actions once. @discussion Should only be used if you want to run additional checks during server operation. Otherwise, use infinite_loop() @param void @see infinite_loop @result bool - True */ public function loop_once() { // Setup Clients Listen Socket For Reading $read[0] = $this->master_socket; for($i = 0; $i < $this->max_clients; $i++) { if(isset($this->clients[$i])) { $read[$i + 1] = $this->clients[$i]->socket; } } // Set up a blocking call to socket_select if(socket_select($read,$write = NULL, $except = NULL, $tv_sec = 5) < 1) { // SocketServer::debug("Problem blocking socket_select?"); return true; } // Handle new Connections if(in_array($this->master_socket, $read)) { for($i = 0; $i < $this->max_clients; $i++) { if(empty($this->clients[$i])) { $temp_sock = $this->master_socket; $this->clients[$i] = new SocketServerClient($this->master_socket,$i); $this->trigger_hooks("CONNECT",$this->clients[$i],""); break; } elseif($i == ($this->max_clients-1)) { SocketServer::debug("Too many clients... "); } } } // Handle Input for($i = 0; $i < $this->max_clients; $i++) // for each client { if(isset($this->clients[$i])) { if(in_array($this->clients[$i]->socket, $read)) { $input = socket_read($this->clients[$i]->socket, $this->max_read); if($input == null) { $this->disconnect($i); } else { SocketServer::debug("{$i}@{$this->clients[$i]->ip} --> {$input}"); $this->trigger_hooks("INPUT",$this->clients[$i],$input); } } } } return true; } /*! @function disconnect @abstract Disconnects a client from the server. @param int - Index of the client to disconnect. @param string - Message to send to the hooks @result void */ public function disconnect($client_index,$message = "") { $i = $client_index; SocketServer::debug("Client {$i} from {$this->clients[$i]->ip} Disconnecting"); $this->trigger_hooks("DISCONNECT",$this->clients[$i],$message); $this->clients[$i]->destroy(); unset($this->clients[$i]); } /*! @function trigger_hooks @abstract Triggers Hooks for a certain command. @param string - Command who's hooks you want to trigger. @param object - The client who activated this command. @param string - The input from the client, or a message to be sent to the hooks. @result void */ public function trigger_hooks($command,&$client,$input) { if(isset($this->hooks[$command])) { foreach($this->hooks[$command] as $function) { SocketServer::debug("Triggering Hook '{$function}' for '{$command}'"); $continue = call_user_func($function,$this,$client,$input); if($continue === FALSE) { break; } } } } /*! @function infinite_loop @abstract Runs the server code until the server is shut down. @see loop_once @param void @result void */ public function infinite_loop() { $test = true; do { $test = $this->loop_once(); } while($test); } /*! @function debug @static @abstract Outputs Text directly. @discussion Yeah, should probably make a way to turn this off. @param string - Text to Output @result void */ public static function debug($text) { echo("{$text}\r\n"); } /*! @function socket_write_smart @static @abstract Writes data to the socket, including the length of the data, and ends it with a CRLF unless specified. @discussion It is perfectly valid for socket_write_smart to return zero which means no bytes have been written. Be sure to use the === operator to check for FALSE in case of an error. @param resource- Socket Instance @param string - Data to write to the socket. @param string - Data to end the line with. Specify a "" if you don't want a line end sent. @result mixed - Returns the number of bytes successfully written to the socket or FALSE on failure. The error code can be retrieved with socket_last_error(). This code may be passed to socket_strerror() to get a textual explanation of the error. */ public static function socket_write_smart(&$sock,$string,$crlf = "\r\n") { SocketServer::debug("< -- {$string}"); if($crlf) { $string = "{$string}{$crlf}"; } return socket_write($sock,$string,strlen($string)); } /*! @function __get @abstract Magic Method used for allowing the reading of protected variables. @discussion You never need to use this method, simply calling $server->variable works because of this method's existence. @param string - Variable to retrieve @result mixed - Returns the reference to the variable called. */ function &__get($name) { return $this->{$name}; } } /*! @class SocketServerClient @author Navarr Barnier @abstract A Client Instance for use with SocketServer */ class SocketServerClient { /*! @var socket @abstract resource - The client's socket resource, for sending and receiving data with. */ protected $socket; /*! @var ip @abstract string - The client's IP address, as seen by the server. */ protected $ip; /*! @var hostname @abstract string - The client's hostname, as seen by the server. @discussion This variable is only set after calling lookup_hostname, as hostname lookups can take up a decent amount of time. @see lookup_hostname */ protected $hostname; /*! @var server_clients_index @abstract int - The index of this client in the SocketServer's client array. */ protected $server_clients_index; /*! @function __construct @param resource- The resource of the socket the client is connecting by, generally the master socket. @param int - The Index in the Server's client array. @result void */ public function __construct(&$socket,$i) { $this->server_clients_index = $i; $this->socket = socket_accept($socket) or die("Failed to Accept"); SocketServer::debug("New Client Connected"); socket_getpeername($this->socket,$ip); $this->ip = $ip; } /*! @function lookup_hostname @abstract Searches for the user's hostname and stores the result to hostname. @see hostname @param void @result string - The hostname on success or the IP address on failure. */ public function lookup_hostname() { $this->hostname = gethostbyaddr($this->ip); return $this->hostname; } /*! @function destroy @abstract Closes the socket. Thats pretty much it. @param void @result void */ public function destroy() { socket_close($this->socket); } function &__get($name) { return $this->{$name}; } function __isset($name) { return isset($this->{$name}); } }
class::SocketServer does all the functions necessary for a server. It binds to the IP address and starts listening to the port. Its easy to specify a maximum number of clients to allow, and the way its coded makes it easily modified.
Here is an example of a server (using this class) that listens for a user to send a string, and then echoes the reverse of that string back to the user.
< ?php // This is PHP5 Code, by the way. require_once("SocketServer.class.php"); // Include the Class File $server = new SocketServer(null,31337); // Create a Server binding to the default IP address (null) and listen to port 31337 for connections $server->max_clients = 10; // Allow no more than 10 people to connect at a time $server->hook("CONNECT","handle_connect"); // Run handle_connect everytime someone connects $server->hook("INPUT","handle_input"); // Run handle_input whenever text is sent to the server $server->infinite_loop(); // Run Server Code Until Process is terminated. /* * All hooked functions are sent the parameters $server (The server class), $client (the connection), and $input (anything sent, if anything was sent) * You should save the variables $server and $client using an ampersand (&) to make sure they are references to the objects and not duplications. */ function handle_connect(&$server,&$client,$input) { SocketServer::socket_write_smart($client->socket,"String? ",""); // Outputs 'String? ' without a Line Ending } function handle_input(&$server,&$client,$input) { $trim = trim($input); // Trim the input, Remove Line Endings and Extra Whitespace. if(strtolower($trim) == "quit") // User Wants to quit the server { SocketServer::socket_write_smart($client->socket,"Oh... Goodbye..."); // Give the user a sad goodbye message, meany! $server->disconnect($client->server_clients_index); // Disconnect this client. return; // Ends the function } $output = strrev($trim); // Reverse the String SocketServer::socket_write_smart($client->socket,$output); // Send the Client back the String SocketServer::socket_write_smart($client->socket,"String? ",""); // Request Another String }
In essence, this class allows you to handle sockets in PHP. Beautifully handle sockets in PHP, that is.