<?php
/**
 * Piwik - Open source web analytics
 *
 * @link http://piwik.org
 * @license http://www.gnu.org/licenses/gpl-3.0.html GPL v3 or later
 *
 * @category Piwik
 * @package Piwik
 */

/**
 * Proxy headers
 *
 * @package Piwik
 */
class Piwik_ProxyHeaders
{
	/**
	 * Get protocol information, with the exception of HTTPS
	 *
	 * @return string protocol information
	 */
	public static function getProtocolInformation()
	{
		if(Piwik_Common::getRequestVar('clientProtocol', 'http', 'string') == 'https')
		{
			return 'https';
		}

		if(isset($_SERVER['SERVER_PORT']) && $_SERVER['SERVER_PORT'] == 443)
		{
			return 'SERVER_PORT=443';
		}

		if(isset($_SERVER['HTTP_X_FORWARDED_PROTO']) && strtolower($_SERVER['HTTP_X_FORWARDED_PROTO']) == 'https')
		{
			return 'X-Forwarded-Proto';
		}

		if(isset($_SERVER['HTTP_X_FORWARDED_SCHEME']) && strtolower($_SERVER['HTTP_X_FORWARDED_SCHEME']) == 'https')
		{
			return 'X-Forwarded-Scheme';
		}

		if(isset($_SERVER['HTTP_X_URL_SCHEME']) && strtolower($_SERVER['HTTP_X_URL_SCHEME']) == 'https')
		{
			return 'X-Url-Scheme';
		}

		return null;
	}

	/**
	 * Get headers present in the HTTP request
	 *
	 * @param array $recognizedHeaders
	 * @return array HTTP headers
	 */
	private static function getHeaders($recognizedHeaders)
	{
		$headers = array();

		foreach($recognizedHeaders as $header)
		{
			if(isset($_SERVER[$header]))
			{
				$headers[] = $header;
			}
		}

		return $headers;
	}

	/**
	 * Detect proxy client headers
	 *
	 * @return array Proxy client HTTP headers
	 */
	public static function getProxyClientHeaders()
	{
		return self::getHeaders(array(
			'HTTP_CF_CONNECTING_IP',
			'HTTP_CLIENT_IP',
			'HTTP_X_FORWARDED_FOR',
		));
	}

	/**
	 * Detect proxy host headers
	 *
	 * @return array Proxy host HTTP headers
	 */
	public static function getProxyHostHeaders()
	{
		return self::getHeaders(array(
			'HTTP_X_FORWARDED_HOST',
		));
	}
}
