<?php
/**
 * See https://developer.valvesoftware.com/wiki/Source_RCON_Protocol for
 * more information about Source RCON Packets
 *
 * @copyright 2013 Chris Churchwell
 */
class Rcon {

	private $host;
	private $port;
	private $password;
	private $timeout;

	private $socket;

	private $authorized;
	private $last_response;

	const PACKET_AUTHORIZE = 5;
	const PACKET_COMMAND = 6;

	const SERVERDATA_AUTH = 3;
	const SERVERDATA_AUTH_RESPONSE = 2;
	const SERVERDATA_EXECCOMMAND = 2;
	const SERVERDATA_RESPONSE_VALUE = 0;

	public function __construct($host, $port, $password, $timeout)
	{
		$this->host = $host;
		$this->port = $port;
		$this->password = $password;
		$this->timeout = $timeout;

	}

	public function get_response() {
		return $this->last_response;
	}

	public function connect() {

		$this->socket = fsockopen($this->host, $this->port, $errno, $errstr, $this->timeout);

		if (!$this->socket)
		{
		  $this->last_response = $errstr;
			return false;
		}

		//set timeout
		stream_set_timeout($this->socket, 3, 0);

		//authorize
		$auth = $this->authorize();

		if ($auth) {
			return true;
		}

		return false;
	}

	public function disconnect()
	{
		if ($this->socket)
		{
			fclose($this->socket);
		}
	}

	public function is_connected() {
		return $this->authorized;
	}

	public function send_command($command)
	{
		if (!$this->is_connected()) return false;

		// send command packet.
		$this->write_packet(Rcon::PACKET_COMMAND, Rcon::SERVERDATA_EXECCOMMAND, $command);

		// get response.
		$response_packet = $this->read_packet();
		if ($response_packet['id'] == Rcon::PACKET_COMMAND)
		{
			if ($response_packet['type'] == Rcon::SERVERDATA_RESPONSE_VALUE)
			{
				$this->last_response = $response_packet['body'];
				return $response_packet['body'];
			}
		}

		return false;
	}

	private function authorize() {
		$this->write_packet(Rcon::PACKET_AUTHORIZE, Rcon::SERVERDATA_AUTH, $this->password);
		$response_packet = $this->read_packet();

		if ($response_packet['type'] == Rcon::SERVERDATA_AUTH_RESPONSE)
		{
			if ($response_packet['id'] == Rcon::PACKET_AUTHORIZE)
			{
				$this->authorized = true;
				return true;
			}
		}

		$this->disconnect();
		return false;
	}

	/**
	 * Writes a packet to the socket stream..
	 */
	private function write_packet($packet_id, $packet_type, $packet_body)
	{
		/*
		Size			32-bit little-endian Signed Integer	 	Varies, see below.
		ID				32-bit little-endian Signed Integer		Varies, see below.
		Type			32-bit little-endian Signed Integer		Varies, see below.
		Body			Null-terminated ASCII String			Varies, see below.
		Empty String	Null-terminated ASCII String			0x00
		*/

		//create packet
		$packet = pack("VV", $packet_id, $packet_type);
		$packet = $packet . $packet_body . "\x00";
		$packet = $packet . "\x00";

		// get packet size.
		$packet_size = strlen($packet);

		// attach size to packet.
		$packet = pack("V", $packet_size) . $packet;

		// write packet.
		fwrite($this->socket, $packet, strlen($packet));

	}

	private function read_packet()
	{
		//get packet size.
		$size_data = fread($this->socket, 4);
		$size_pack = unpack("V1size", $size_data);
		$size = $size_pack['size'];

		// if size is > 4096, the response will be in multiple packets.
		// this needs to be address. get more info about multi-packet responses
		// from the RCON protocol specification at
		// https://developer.valvesoftware.com/wiki/Source_RCON_Protocol
		// currently, this script does not support multi-packet responses.

		$packet_data = fread($this->socket, $size);
		$packet_pack = unpack("V1id/V1type/a*body", $packet_data);

		return $packet_pack;
	}
}