silverstripe-framework/Control/HTTP.php

<?php

namespace SilverStripe\Control;

use SilverStripe\Assets\File;
use SilverStripe\Core\Config\Configurable;
use SilverStripe\Core\Convert;
use SilverStripe\Core\Config\Config;
use InvalidArgumentException;
use finfo;

/**
 * A class with HTTP-related helpers. Like Debug, this is more a bundle of methods than a class.
 */
class HTTP {
	use Configurable;

	/**
	 * @var int
	 */
	protected static $cache_age = 0;

	/**
	 * @var int
	 */
	protected static $modification_date = null;

	/**
	 * @var string
	 */
	protected static $etag = null;

	/**
	 * @config
	 *
	 * @var bool
	 */
	private static $cache_ajax_requests = true;

	/**
	 * Turns a local system filename into a URL by comparing it to the script filename.
	 *
	 * @param string $filename
	 * @return string
	 */
	public static function filename2url($filename) {
		$filename = realpath($filename);
		if (!$filename) {
			return null;
		}

		// Filter files outside of the webroot
		$base = realpath(BASE_PATH);
		$baseLength = strlen($base);
		if (substr($filename, 0, $baseLength) !== $base) {
			return null;
		}

		$relativePath = ltrim(substr($filename, $baseLength), '/\\');
		return Director::absoluteURL($relativePath);
	}

	/**
	 * Turn all relative URLs in the content to absolute URLs.
	 *
	 * @param string $html
	 *
	 * @return string
	 */
	public static function absoluteURLs($html) {
		$html = str_replace('$CurrentPageURL', $_SERVER['REQUEST_URI'], $html);
		return HTTP::urlRewriter($html, function($url) {
			//no need to rewrite, if uri has a protocol (determined here by existence of reserved URI character ":")
			if(preg_match('/^\w+:/', $url)) {
				return $url;
			}
			return Director::absoluteURL($url, true);
		});
	}

	/**
	 * Rewrite all the URLs in the given content, evaluating the given string as PHP code.
	 *
	 * Put $URL where you want the URL to appear, however, you can't embed $URL in strings, for example:
	 * <ul>
	 * <li><code>'"../../" . $URL'</code></li>
	 * <li><code>'myRewriter($URL)'</code></li>
	 * <li><code>'(substr($URL, 0, 1)=="/") ? "../" . substr($URL, 1) : $URL'</code></li>
	 * </ul>
	 *
	 * As of 3.2 $code should be a callable which takes a single parameter and returns the rewritten,
	 * for example:
	 * <code>
	 * function($url) {
	 *		return Director::absoluteURL($url, true);
	 * }
	 * </code>
	 *
	 * @param string $content The HTML to search for links to rewrite.
	 * @param callable $code Either a string that can evaluate to an expression to rewrite links
	 * (depreciated), or a callable that takes a single parameter and returns the rewritten URL.
	 *
	 * @return string The content with all links rewritten as per the logic specified in $code.
	 */
	public static function urlRewriter($content, $code) {
		if(!is_callable($code)) {
			throw new InvalidArgumentException(
				'HTTP::urlRewriter expects a callable as the second parameter'
			);
		}

		// Replace attributes
		$attribs = array("src", "background", "a" => "href", "link" => "href", "base" => "href");
		$regExps = [];
		foreach($attribs as $tag => $attrib) {
			if(!is_numeric($tag)) {
				$tagPrefix = "$tag ";
			} else {
				$tagPrefix = "";
			}

			$regExps[] = "/(<{$tagPrefix}[^>]*$attrib *= *\")([^\"]*)(\")/i";
			$regExps[] = "/(<{$tagPrefix}[^>]*$attrib *= *')([^']*)(')/i";
			$regExps[] = "/(<{$tagPrefix}[^>]*$attrib *= *)([^\"' ]*)( )/i";
		}
		// Replace css styles
		// @todo - http://www.css3.info/preview/multiple-backgrounds/
		$styles = array('background-image', 'background', 'list-style-image', 'list-style', 'content');
		foreach($styles as $style) {
			$regExps[] = "/($style:[^;]*url *\\(\")([^\"]+)(\"\\))/i";
			$regExps[] = "/($style:[^;]*url *\\(')([^']+)('\\))/i";
			$regExps[] = "/($style:[^;]*url *\\()([^\"\\)')]+)(\\))/i";
		}

		// Callback for regexp replacement
		$callback = function($matches) use($code) {
			// Decode HTML attribute
			$URL = Convert::xml2raw($matches[2]);
			$rewritten = $code($URL);
			return $matches[1] . Convert::raw2xml($rewritten) . $matches[3];
		};

		// Execute each expression
		foreach($regExps as $regExp) {
			$content = preg_replace_callback($regExp, $callback, $content);
		}

		return $content;
	}

	/**
	 * Will try to include a GET parameter for an existing URL, preserving existing parameters and
	 * fragments. If no URL is given, falls back to $_SERVER['REQUEST_URI']. Uses parse_url() to
	 * dissect the URL, and http_build_query() to reconstruct it with the additional parameter.
	 * Converts any '&' (ampersand) URL parameter separators to the more XHTML compliant '&amp;'.
	 *
	 * CAUTION: If the URL is determined to be relative, it is prepended with Director::absoluteBaseURL().
	 * This method will always return an absolute URL because Director::makeRelative() can lead to
	 * inconsistent results.
	 *
	 * @param string $varname
	 * @param string $varvalue
	 * @param string $currentURL Relative or absolute URL.
	 * @param string $separator Separator for http_build_query().
	 *
	 * @return string
	 */
	public static function setGetVar($varname, $varvalue, $currentURL = null, $separator = '&amp;') {
		$uri = $currentURL ? $currentURL : Director::makeRelative($_SERVER['REQUEST_URI']);

		$isRelative = false;
		// We need absolute URLs for parse_url()
		if(Director::is_relative_url($uri)) {
			$uri = Director::absoluteBaseURL() . $uri;
			$isRelative = true;
		}

		// try to parse uri
		$parts = parse_url($uri);
		if(!$parts) {
			throw new InvalidArgumentException("Can't parse URL: " . $uri);
		}

		// Parse params and add new variable
		$params = array();
		if(isset($parts['query'])) parse_str($parts['query'], $params);
		$params[$varname] = $varvalue;

		// Generate URI segments and formatting
		$scheme = (isset($parts['scheme'])) ? $parts['scheme'] : 'http';
		$user = (isset($parts['user']) && $parts['user'] != '')  ? $parts['user'] : '';

		if($user != '') {
			// format in either user:pass@host.com or user@host.com
			$user .= (isset($parts['pass']) && $parts['pass'] != '') ? ':' . $parts['pass'] . '@' : '@';
		}

		$host = (isset($parts['host'])) ? $parts['host'] : '';
		$port = (isset($parts['port']) && $parts['port'] != '') ? ':'.$parts['port'] : '';
		$path = (isset($parts['path']) && $parts['path'] != '') ? $parts['path'] : '';

		// handle URL params which are existing / new
		$params = ($params) ?  '?' . http_build_query($params, null, $separator) : '';

		// keep fragments (anchors) intact.
		$fragment = (isset($parts['fragment']) && $parts['fragment'] != '') ?  '#'.$parts['fragment'] : '';

		// Recompile URI segments
		$newUri =  $scheme . '://' . $user . $host . $port . $path . $params . $fragment;

		if($isRelative) return Director::makeRelative($newUri);

		return $newUri;
	}

	/**
	 * @param string $varname
	 * @param string $varvalue
	 * @param null|string $currentURL
	 *
	 * @return string
	 */
	public static function RAW_setGetVar($varname, $varvalue, $currentURL = null) {
		$url = self::setGetVar($varname, $varvalue, $currentURL);
		return Convert::xml2raw($url);
	}

	/**
	 * Search for all tags with a specific attribute, then return the value of that attribute in a
	 * flat array.
	 *
	 * @param string $content
	 * @param array $attributes An array of tags to attributes, for example "[a] => 'href', [div] => 'id'"
	 *
	 * @return array
	 */
	public static function findByTagAndAttribute($content, $attributes) {
		$regexes = array();

		foreach($attributes as $tag => $attribute) {
			$regexes[] = "/<{$tag} [^>]*$attribute *= *([\"'])(.*?)\\1[^>]*>/i";
			$regexes[] = "/<{$tag} [^>]*$attribute *= *([^ \"'>]+)/i";
		}

		$result = array();

		if($regexes) foreach($regexes as $regex) {
			if(preg_match_all($regex, $content, $matches)) {
				$result = array_merge_recursive($result, (isset($matches[2]) ? $matches[2] : $matches[1]));
			}
		}

		return count($result) ? $result : null;
	}

	/**
	 * @param string $content
	 *
	 * @return array
	 */
	public static function getLinksIn($content) {
		return self::findByTagAndAttribute($content, array("a" => "href"));
	}

	/**
	 * @param string $content
	 *
	 * @return array
	 */
	public static function getImagesIn($content) {
		return self::findByTagAndAttribute($content, array("img" => "src"));
	}

	/**
	 * Get the MIME type based on a file's extension. If the finfo class exists in PHP, and the file
	 * exists relative to the project root, then use that extension, otherwise fallback to a list of
	 * commonly known MIME types.
	 *
	 * @param string $filename
	 *
	 * @return string
	 */
	public static function get_mime_type($filename) {
		// If the finfo module is compiled into PHP, use it.
		$path = BASE_PATH . DIRECTORY_SEPARATOR . $filename;
		if(class_exists('finfo') && file_exists($path)) {
			$finfo = new finfo(FILEINFO_MIME_TYPE);
			return $finfo->file($path);
		}

		// Fallback to use the list from the HTTP.yml configuration and rely on the file extension
		// to get the file mime-type
		$ext = File::get_file_extension($filename);
		// Get the mime-types
		$mimeTypes = HTTP::config()->get('MimeTypes');

		// The mime type doesn't exist
		if(!isset($mimeTypes[$ext])) {
			return 'application/unknown';
		}

		return $mimeTypes[$ext];
	}

	/**
	 * Set the maximum age of this page in web caches, in seconds.
	 *
	 * @param int $age
	 */
	public static function set_cache_age($age) {
		self::$cache_age = $age;
	}

	/**
	 * @param string $dateString
	 */
	public static function register_modification_date($dateString) {
		$timestamp = strtotime($dateString);
		if($timestamp > self::$modification_date)
			self::$modification_date = $timestamp;
	}

	/**
	 * @param int $timestamp
	 */
	public static function register_modification_timestamp($timestamp) {
		if($timestamp > self::$modification_date)
			self::$modification_date = $timestamp;
	}

	/**
	 * @param string $etag
	 */
	public static function register_etag($etag) {
		if (0 !== strpos($etag, '"')) {
			$etag = sprintf('"%s"', $etag);
		}
		self::$etag = $etag;
	}

	/**
	 * Add the appropriate caching headers to the response, including If-Modified-Since / 304 handling.
	 * Note that setting HTTP::$cache_age will overrule any cache headers set by PHP's
	 * session_cache_limiter functionality. It is your responsibility to ensure only cacheable data
	 * is in fact cached, and HTTP::$cache_age isn't set when the HTTP body contains session-specific
	 * content.
	 *
	 * Omitting the $body argument or passing a string is deprecated; in these cases, the headers are
	 * output directly.
	 *
	 * @param SS_HTTPResponse $body
	 */
	public static function add_cache_headers($body = null) {
		$cacheAge = self::$cache_age;

		// Validate argument
		if($body && !($body instanceof SS_HTTPResponse)) {
			user_error("HTTP::add_cache_headers() must be passed an SS_HTTPResponse object", E_USER_WARNING);
			$body = null;
		}

		// Development sites have frequently changing templates; this can get stuffed up by the code
		// below.
		if(Director::isDev()) {
			$cacheAge = 0;
		}

		// The headers have been sent and we don't have an SS_HTTPResponse object to attach things to; no point in
		// us trying.
		if(headers_sent() && !$body) {
			return;
		}

		// Populate $responseHeaders with all the headers that we want to build
		$responseHeaders = array();

		$cacheControlHeaders = Config::inst()->get(__CLASS__, 'cache_control');


		// currently using a config setting to cancel this, seems to be so that the CMS caches ajax requests
		if(function_exists('apache_request_headers') && Config::inst()->get(__CLASS__, 'cache_ajax_requests')) {
			$requestHeaders = array_change_key_case(apache_request_headers(), CASE_LOWER);
			if(
				isset($requestHeaders['x-requested-with'])
				&& $requestHeaders['x-requested-with']=='XMLHttpRequest'
			) {
				$cacheAge = 0;
			}
		}

		if($cacheAge > 0) {
			$cacheControlHeaders['max-age'] = self::$cache_age;

			// Set empty pragma to avoid PHP's session_cache_limiter adding conflicting caching information,
			// defaulting to "nocache" on most PHP configurations (see http://php.net/session_cache_limiter).
			// Since it's a deprecated HTTP 1.0 option, all modern HTTP clients and proxies should
			// prefer the caching information indicated through the "Cache-Control" header.
			$responseHeaders["Pragma"] = "";

			// To do: User-Agent should only be added in situations where you *are* actually
			// varying according to user-agent.
			$vary = Config::inst()->get(__CLASS__, 'vary');
			if ($vary && strlen($vary)) {
				$responseHeaders['Vary'] = $vary;
			}
		}
		else {
			$contentDisposition = null;
			if($body) {
				// Grab header for checking. Unfortunately HTTPRequest uses a mistyped variant.
				$contentDisposition = $body->getHeader('Content-disposition');
				if (!$contentDisposition) {
					$contentDisposition = $body->getHeader('Content-Disposition');
				}
			}

			if(
				$body &&
				Director::is_https() &&
				isset($_SERVER['HTTP_USER_AGENT']) &&
				strstr($_SERVER['HTTP_USER_AGENT'], 'MSIE')==true &&
				strstr($contentDisposition, 'attachment;')==true
			) {
				// IE6-IE8 have problems saving files when https and no-cache are used
				// (http://support.microsoft.com/kb/323308)
				// Note: this is also fixable by ticking "Do not save encrypted pages to disk" in advanced options.
				$cacheControlHeaders['max-age'] = 3;

				// Set empty pragma to avoid PHP's session_cache_limiter adding conflicting caching information,
				// defaulting to "nocache" on most PHP configurations (see http://php.net/session_cache_limiter).
				// Since it's a deprecated HTTP 1.0 option, all modern HTTP clients and proxies should
				// prefer the caching information indicated through the "Cache-Control" header.
				$responseHeaders["Pragma"] = "";
			} else {
				$cacheControlHeaders['no-cache'] = "true";
				$cacheControlHeaders['no-store'] = "true";
			}
		}

		foreach($cacheControlHeaders as $header => $value) {
			if(is_null($value)) {
				unset($cacheControlHeaders[$header]);
			} elseif((is_bool($value) && $value) || $value === "true") {
				$cacheControlHeaders[$header] = $header;
			} else {
				$cacheControlHeaders[$header] = $header."=".$value;
			}
		}

		$responseHeaders['Cache-Control'] = implode(', ', $cacheControlHeaders);
		unset($cacheControlHeaders, $header, $value);

		if(self::$modification_date && $cacheAge > 0) {
			$responseHeaders["Last-Modified"] = self::gmt_date(self::$modification_date);

			// Chrome ignores Varies when redirecting back (http://code.google.com/p/chromium/issues/detail?id=79758)
			// which means that if you log out, you get redirected back to a page which Chrome then checks against
			// last-modified (which passes, getting a 304)
			// when it shouldn't be trying to use that page at all because it's the "logged in" version.
			// By also using and etag that includes both the modification date and all the varies
			// values which we also check against we can catch this and not return a 304
			$etagParts = array(self::$modification_date, serialize($_COOKIE));
			$etagParts[] = Director::is_https() ? 'https' : 'http';
			if (isset($_SERVER['HTTP_USER_AGENT'])) {
				$etagParts[] = $_SERVER['HTTP_USER_AGENT'];
			}
			if (isset($_SERVER['HTTP_ACCEPT'])) {
				$etagParts[] = $_SERVER['HTTP_ACCEPT'];
			}

			$etag = sha1(implode(':', $etagParts));
			$responseHeaders["ETag"] = $etag;

			// 304 response detection
			if(isset($_SERVER['HTTP_IF_MODIFIED_SINCE'])) {
				$ifModifiedSince = strtotime(stripslashes($_SERVER['HTTP_IF_MODIFIED_SINCE']));

				// As above, only 304 if the last request had all the same varies values
				// (or the etag isn't passed as part of the request - but with chrome it always is)
				$matchesEtag = !isset($_SERVER['HTTP_IF_NONE_MATCH']) || $_SERVER['HTTP_IF_NONE_MATCH'] == $etag;

				if($ifModifiedSince >= self::$modification_date && $matchesEtag) {
					if($body) {
						$body->setStatusCode(304);
						$body->setBody('');
					} else {
						header('HTTP/1.0 304 Not Modified');
						die();
					}
				}
			}

			$expires = time() + $cacheAge;
			$responseHeaders["Expires"] = self::gmt_date($expires);
		}

		if(self::$etag) {
			$responseHeaders['ETag'] = self::$etag;
		}

		// etag needs to be a quoted string according to HTTP spec
		if (!empty($responseHeaders['ETag']) && 0 !== strpos($responseHeaders['ETag'], '"')) {
			$responseHeaders['ETag'] = sprintf('"%s"', $responseHeaders['ETag']);
		}

		// Now that we've generated them, either output them or attach them to the SS_HTTPResponse as appropriate
		foreach($responseHeaders as $k => $v) {
			if($body) {
				// Set the header now if it's not already set.
				if ($body->getHeader($k) === null) {
					$body->addHeader($k, $v);
				}
			} elseif(!headers_sent()) {
				header("$k: $v");
			}
		}
	}


	/**
	 * Return an {@link http://www.faqs.org/rfcs/rfc2822 RFC 2822} date in the GMT timezone (a timestamp
	 * is always in GMT: the number of seconds since January 1 1970 00:00:00 GMT)
	 *
	 * @param int $timestamp
	 *
	 * @return string
	 */
	public static function gmt_date($timestamp) {
		return gmdate('D, d M Y H:i:s', $timestamp) . ' GMT';
	}

	/**
	 * Return static variable cache_age in second
	 *
	 * @return int
	 */
	public static function get_cache_age() {
		return self::$cache_age;
	}

}