/**
	 * Determines own remote IP address (e.g. can be used to probe if we are
	 * reachable from outside by determining external IP and then connect to it.
	 * This is accomblished by connecting to the IP of www.shipsimu.org which
	 * should default to 188.138.90.169 and requesting /ip.php which does only
	 * return the content of $_SERVER['REMOTE_ADDR']. Of course, this method
	 * requires a working Internet connection.
	 *
	 * This method is taken from a user comment on php.net and heavily rewritten.
	 * Compare to following link:
	 * http://de.php.net/manual/en/function.socket-create.php#49368
	 *
	 * @return	$externalAddress	The determined external IP address
	 * @todo	Make IP, host name, port and script name configurable
	 */
	public static function determineExternalAddress () {
		// Get helper instance
		$helperInstance = new ConsoleTools();

		// First get a socket
		// @TODO Add some DNS caching here

		// Open connection
		if ($helperInstance->isProxyUsed() === TRUE) {
			// Resolve hostname into IP address
			$ip = $helperInstance->resolveIpAddress($helperInstance->getConfigInstance()->getConfigEntry('proxy_host'));

			// Connect to host through proxy connection
			$socketResource = fsockopen($ip, $helperInstance->getConfigInstance()->getConfigEntry('proxy_port'), $errorNo, $errorStr, 30);
		} else {
			// Connect to host directly
			$socketResource = fsockopen('188.138.90.169', 80, $errorNo, $errorStr, 30);
		}

		// Check if there was an error else
		if ($errorNo > 0) {
			// Then throw again
			throw new InvalidSocketException(array($helperInstance, $socketResource, $errorNo, $errorStr), BaseListener::EXCEPTION_INVALID_SOCKET);
		} // END - if

		// Prepare the GET request
		$request  = 'GET ' . ($helperInstance->isProxyUsed() === TRUE ? 'http://shipsimu.org' : '') . '/ip.php HTTP/1.0' . self::HTTP_EOL;
		$request .= 'Host: shipsimu.org' . self::HTTP_EOL;
		$request .= 'User-Agent: ' . $this->getUserAgent() . self::HTTP_EOL;
		$request .= 'Connection: close' . self::HTTP_EOL;

		// Do we use proxy?
		if ($helperInstance->isProxyUsed() === TRUE) {
			// CONNECT method?
			if ($helperInstance->getConfigInstance()->getConfigEntry('proxy_connect_method') == 'Y') {
				// Setup proxy tunnel
				$response = $helperInstance->setupProxyTunnel('shipsimu.org', 80, $socketResource);

				// If the response is invalid, abort
				if ((count($response) == 3) && (empty($response[0])) && (empty($response[1])) && (empty($response[2]))) {
					// Invalid response!
					$helperInstance->debugBackTrace('Proxy tunnel not working: response=' . print_r($response, TRUE));
				} // END - if
			} else {
				// Add header for proxy
				$request .= 'Proxy-Connection: Keep-Alive' . self::HTTP_EOL;
			}
		} // END - if

		// Add last HTTP_EOL
		$request .= self::HTTP_EOL;

		// Send it to the socket
		fwrite($socketResource, $request);

		// Init IP (this will always be the last line)
		$externalAddress = 'invalid';

		// And read the reply
		while (!feof($socketResource)) {
			// Get line
			$externalAddress = trim(fgets($socketResource, 128));

			// Detect HTTP response
			if ((substr($externalAddress, 0, 7) == 'HTTP/1.') && (substr($externalAddress, -6, 6) != '200 OK')) {
				// Stop processing
				break;
			} // END - if
		} // END - while

		// Close socket
		fclose($socketResource);


		// Debug message
		/* DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput('CONSOLE-TOOLS[' . __METHOD__ . ':' . __LINE__ . ']: Resolved external address: ' . $externalAddress);

		// Return determined external IP
		return $externalAddress;
	}