First version of blacklist plugin

First version of blacklist plugin. Replaces custom code in identi.ca's
config.php, which was getting scary and long. Also correctly handles
changed nicknames or URLs in profile settings and using 'forbidden'
URLs in notice text.

plugins/Blacklist/BlacklistPlugin.php

@@ -0,0 +1,203 @@
+<?php
+/**
+ * StatusNet, the distributed open-source microblogging tool
+ *
+ * Plugin to prevent use of nicknames or URLs on a blacklist
+ *
+ * PHP version 5
+ *
+ * LICENCE: 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 <http://www.gnu.org/licenses/>.
+ *
+ * @category  Action
+ * @package   StatusNet
+ * @author    Evan Prodromou <evan@status.net>
+ * @copyright 2009 StatusNet Inc.
+ * @license   http://www.fsf.org/licensing/licenses/agpl-3.0.html GNU Affero General Public License version 3.0
+ * @link      http://status.net/
+ */
+
+if (!defined('STATUSNET')) {
+    exit(1);
+}
+
+/**
+ * Plugin to prevent use of nicknames or URLs on a blacklist
+ *
+ * @category Plugin
+ * @package  StatusNet
+ * @author   Evan Prodromou <evan@status.net>
+ * @license  http://www.fsf.org/licensing/licenses/agpl-3.0.html GNU Affero General Public License version 3.0
+ * @link     http://status.net/
+ */
+
+class BlacklistPlugin extends Plugin
+{
+    public $nicknames = array();
+    public $urls      = array();
+
+    /**
+     * Hook registration to prevent blacklisted homepages or nicknames
+     *
+     * Throws an exception if there's a blacklisted homepage or nickname.
+     *
+     * @param Action $action Action being called (usually register)
+     *
+     * @return boolean hook value
+     */
+
+    function onStartRegistrationTry($action)
+    {
+        $homepage = strtolower($action->trimmed('homepage'));
+
+        if (!empty($homepage)) {
+            if (!$this->_checkUrl($homepage)) {
+                $msg = sprintf(_m("You may not register with homepage '%s'"),
+                               $homepage);
+                throw new ClientException($msg);
+            }
+        }
+
+        $nickname = strtolower($action->trimmed('nickname'));
+
+        if (!empty($nickname)) {
+            if (!$this->_checkNickname($nickname)) {
+                $msg = sprintf(_m("You may not register with nickname '%s'"),
+                               $nickname);
+                throw new ClientException($msg);
+            }
+        }
+
+        return true;
+    }
+
+    /**
+     * Hook profile update to prevent blacklisted homepages or nicknames
+     *
+     * Throws an exception if there's a blacklisted homepage or nickname.
+     *
+     * @param Action $action Action being called (usually register)
+     *
+     * @return boolean hook value
+     */
+
+    function onStartProfileSaveForm($action)
+    {
+        $homepage = strtolower($action->trimmed('homepage'));
+
+        if (!empty($homepage)) {
+            if (!$this->_checkUrl($homepage)) {
+                $msg = sprintf(_m("You may not use homepage '%s'"),
+                               $homepage);
+                throw new ClientException($msg);
+            }
+        }
+
+        $nickname = strtolower($action->trimmed('nickname'));
+
+        if (!empty($nickname)) {
+            if (!$this->_checkNickname($nickname)) {
+                $msg = sprintf(_m("You may not use nickname '%s'"),
+                               $nickname);
+                throw new ClientException($msg);
+            }
+        }
+
+        return true;
+    }
+
+    /**
+     * Hook notice save to prevent blacklisted urls
+     *
+     * Throws an exception if there's a blacklisted url in the content.
+     *
+     * @param Notice &$notice Notice being saved
+     *
+     * @return boolean hook value
+     */
+
+    function onStartNoticeSave(&$notice)
+    {
+        common_replace_urls_callback($notice->content,
+                                     array($this, 'checkNoticeUrl'));
+        return true;
+    }
+
+    /**
+     * Helper callback for notice save
+     *
+     * Throws an exception if there's a blacklisted url in the content.
+     *
+     * @param string $url URL in the notice content
+     *
+     * @return boolean hook value
+     */
+
+    function checkNoticeUrl($url)
+    {
+        // It comes in special'd, so we unspecial it
+        // before comparing against patterns
+
+        $url = htmlspecialchars_decode($url);
+
+        if (!$this->_checkUrl($url)) {
+            $msg = sprintf(_m("You may not use url '%s' in notices"),
+                           $url);
+            throw new ClientException($msg);
+        }
+
+        return $url;
+    }
+
+    /**
+     * Helper for checking URLs
+     *
+     * Checks an URL against our patterns for a match.
+     *
+     * @param string $url URL to check
+     *
+     * @return boolean true means it's OK, false means it's bad
+     */
+
+    private function _checkUrl($url)
+    {
+        foreach ($this->urls as $pattern) {
+            if (preg_match("/$pattern/", $url)) {
+                return false;
+            }
+        }
+
+        return true;
+    }
+
+    /**
+     * Helper for checking nicknames
+     *
+     * Checks a nickname against our patterns for a match.
+     *
+     * @param string $nickname nickname to check
+     *
+     * @return boolean true means it's OK, false means it's bad
+     */
+
+    private function _checkNickname($nickname)
+    {
+        foreach ($this->nicknames as $pattern) {
+            if (preg_match("/$pattern/", $nickname)) {
+                return false;
+            }
+        }
+
+        return true;
+    }
+}