<?php
/**
- * @file src/Util/Network.php
+ * @copyright Copyright (C) 2020, Friendica
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <https://www.gnu.org/licenses/>.
+ *
*/
+
namespace Friendica\Util;
use DOMDocument;
return self::unparseURL($parsed);
}
+
+ /**
+ * Generates ETag and Last-Modified response headers and checks them against
+ * If-None-Match and If-Modified-Since request headers if present.
+ *
+ * Blocking function, sends 304 headers and exits if check passes.
+ *
+ * @param string $etag The page etag
+ * @param string $last_modified The page last modification UTC date
+ * @throws \Exception
+ */
+ public static function checkEtagModified(string $etag, string $last_modified)
+ {
+ $last_modified = DateTimeFormat::utc($last_modified, 'D, d M Y H:i:s') . ' GMT';
+
+ /**
+ * @see http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.26
+ */
+ $if_none_match = filter_input(INPUT_SERVER, 'HTTP_IF_NONE_MATCH');
+ $if_modified_since = filter_input(INPUT_SERVER, 'HTTP_IF_MODIFIED_SINCE');
+ $flag_not_modified = null;
+ if ($if_none_match) {
+ $result = [];
+ preg_match('/^(?:W\/")?([^"]+)"?$/i', $etag, $result);
+ $etagTrimmed = $result[1];
+ // Lazy exact ETag match, could check weak/strong ETags
+ $flag_not_modified = $if_none_match == '*' || strpos($if_none_match, $etagTrimmed) !== false;
+ }
+
+ if ($if_modified_since && (!$if_none_match || $flag_not_modified)) {
+ // Lazy exact Last-Modified match, could check If-Modified-Since validity
+ $flag_not_modified = $if_modified_since == $last_modified;
+ }
+
+ header('Etag: ' . $etag);
+ header('Last-Modified: ' . $last_modified);
+
+ if ($flag_not_modified) {
+ header("HTTP/1.1 304 Not Modified");
+ exit;
+ }
+ }
}