core: Refactor bridge whitelisting

- Move all whitelisting functionality inside Bridge.php
- Set default whitelist once in index.php using Bridge::setWhitelist()
- Include bridge sanitizing inside Bridge.php
    Bridge::sanitizeBridgeName($name)

Bridge.php now maintains the whitelist internally.

lib/Bridge.php

@@ -4,6 +4,12 @@ class Bridge {
 
 	static protected $dirBridge;
 
+	/**
+	 * Holds the active whitelist.
+	 * Use Bridge::getWhitelist() instead of accessing this parameter directly!
+	 */
+	private static $whitelist = array();
+
 	public function __construct(){
 		throw new \LogicException('Please use ' . __CLASS__ . '::create for new object.');
 	}
@@ -78,11 +84,80 @@ EOD;
 		return $listBridge;
 	}
 
-	static public function isWhitelisted($whitelist, $name){
-		return in_array($name, $whitelist)
-		|| in_array($name . '.php', $whitelist)
-		|| in_array($name . 'bridge', $whitelist) // DEPRECATED
-		|| in_array($name . 'bridge.php', $whitelist) // DEPRECATED
-		|| (count($whitelist) === 1 && trim($whitelist[0]) === '*');
+	/**
+	 * @return bool Returns true if the given bridge is whitelisted.
+	 */
+	static public function isWhitelisted($name){
+		return in_array(Bridge::sanitizeBridgeName($name), Bridge::getWhitelist());
+	}
+
+	/**
+	 * On first call reads the whitelist from WHITELIST. Each line in the file
+	 * specifies one bridge that will be placed on the whitelist. An empty file
+	 * disables all bridges. '*' enables all bridges.
+	 *
+	 * @return array Returns a list of whitelisted bridges
+	 */
+	public static function getWhitelist() {
+
+		static $firstCall = true; // Initialized on first call
+
+		if($firstCall) {
+
+			// Create initial whitelist or load from disk
+			if (!file_exists(WHITELIST) && !empty(Bridge::$whitelist)) {
+				file_put_contents(WHITELIST, implode("\n", Bridge::$whitelist));
+			} else {
+
+				$contents = trim(file_get_contents(WHITELIST));
+
+				if($contents === '*') { // Whitelist all bridges
+					Bridge::$whitelist = Bridge::listBridges();
+				} else {
+					Bridge::$whitelist = array_map('Bridge::sanitizeBridgeName', explode("\n", $contents));
+				}
+
+			}
+
+		}
+
+		return Bridge::$whitelist;
+
+	}
+
+	public static function setWhitelist($default = array()) {
+		Bridge::$whitelist = array_map('Bridge::sanitizeBridgeName', $default);
+	}
+
+	/**
+	 * @return string Returns a sanitized bridge name if the given name has been
+	 * found valid, null otherwise.
+	 */
+	private static function sanitizeBridgeName($name) {
+
+		if(is_string($name)) {
+
+			// Trim trailing '.php' if exists
+			if(preg_match('/(.+)(?:\.php)/', $name, $matches)) {
+				$name = $matches[1];
+			}
+
+			// Trim trailing 'Bridge' if exists
+			if(preg_match('/(.+)(?:Bridge)/i', $name, $matches)) {
+				$name = $matches[1];
+			}
+
+			// The name is valid if a corresponding bridge file is found on disk
+			if(in_array(strtolower($name), array_map('strtolower', Bridge::listBridges()))) {
+				$index = array_search(strtolower($name), array_map('strtolower', Bridge::listBridges()));
+				return Bridge::listBridges()[$index];
+			}
+
+			Debug::log('Invalid bridge name specified: "' . $name . '"!');
+
+		}
+
+		return null; // Bad parameter
+
 	}
 }