<?php /** * Functions to help implement an external link filter for spam control. * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 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 General Public License for more details. * * You should have received a copy of the GNU General Public License along * with this program; if not, write to the Free Software Foundation, Inc., * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. * http://www.gnu.org/copyleft/gpl.html * * @file */ /** * Some functions to help implement an external link filter for spam control. * * @todo implement the filter. Currently these are just some functions to help * maintenance/cleanupSpam.php remove links to a single specified domain. The * next thing is to implement functions for checking a given page against a big * list of domains. * * Another cool thing to do would be a web interface for fast spam removal. */ class LinkFilter { /** * Check whether $content contains a link to $filterEntry * * @param Content $content Content to check * @param string $filterEntry Domainparts, see makeRegex() for more details * @return int 0 if no match or 1 if there's at least one match */ static function matchEntry( Content $content, $filterEntry ) { if ( !( $content instanceof TextContent ) ) { //TODO: handle other types of content too. // Maybe create ContentHandler::matchFilter( LinkFilter ). // Think about a common base class for LinkFilter and MagicWord. return 0; } $text = $content->getNativeData(); $regex = LinkFilter::makeRegex( $filterEntry ); return preg_match( $regex, $text ); } /** * Builds a regex pattern for $filterEntry. * * @param string $filterEntry URL, if it begins with "*.", it'll be * replaced to match any subdomain * @return string Regex pattern, for preg_match() */ private static function makeRegex( $filterEntry ) { $regex = '!http://'; if ( substr( $filterEntry, 0, 2 ) == '*.' ) { $regex .= '(?:[A-Za-z0-9.-]+\.|)'; $filterEntry = substr( $filterEntry, 2 ); } $regex .= preg_quote( $filterEntry, '!' ) . '!Si'; return $regex; } /** * Make an array to be used for calls to DatabaseBase::buildLike(), which * will match the specified string. There are several kinds of filter entry: * *.domain.com - Produces http://com.domain.%, matches domain.com * and www.domain.com * domain.com - Produces http://com.domain./%, matches domain.com * or domain.com/ but not www.domain.com * *.domain.com/x - Produces http://com.domain.%/x%, matches * www.domain.com/xy * domain.com/x - Produces http://com.domain./x%, matches * domain.com/xy but not www.domain.com/xy * * Asterisks in any other location are considered invalid. * * This function does the same as wfMakeUrlIndexes(), except it also takes care * of adding wildcards * * @param string $filterEntry Domainparts * @param string $protocol Protocol (default http://) * @return array Array to be passed to DatabaseBase::buildLike() or false on error */ public static function makeLikeArray( $filterEntry, $protocol = 'http://' ) { $db = wfGetDB( DB_SLAVE ); $target = $protocol . $filterEntry; $bits = wfParseUrl( $target ); if ( $bits == false ) { // Unknown protocol? return false; } if ( substr( $bits['host'], 0, 2 ) == '*.' ) { $subdomains = true; $bits['host'] = substr( $bits['host'], 2 ); if ( $bits['host'] == '' ) { // We don't want to make a clause that will match everything, // that could be dangerous return false; } } else { $subdomains = false; } // Reverse the labels in the hostname, convert to lower case // For emails reverse domainpart only if ( $bits['scheme'] === 'mailto' && strpos( $bits['host'], '@' ) ) { // complete email address $mailparts = explode( '@', $bits['host'] ); $domainpart = strtolower( implode( '.', array_reverse( explode( '.', $mailparts[1] ) ) ) ); $bits['host'] = $domainpart . '@' . $mailparts[0]; } elseif ( $bits['scheme'] === 'mailto' ) { // domainpart of email address only, do not add '.' $bits['host'] = strtolower( implode( '.', array_reverse( explode( '.', $bits['host'] ) ) ) ); } else { $bits['host'] = strtolower( implode( '.', array_reverse( explode( '.', $bits['host'] ) ) ) ); if ( substr( $bits['host'], -1, 1 ) !== '.' ) { $bits['host'] .= '.'; } } $like[] = $bits['scheme'] . $bits['delimiter'] . $bits['host']; if ( $subdomains ) { $like[] = $db->anyString(); } if ( isset( $bits['port'] ) ) { $like[] = ':' . $bits['port']; } if ( isset( $bits['path'] ) ) { $like[] = $bits['path']; } elseif ( !$subdomains ) { $like[] = '/'; } if ( isset( $bits['query'] ) ) { $like[] = '?' . $bits['query']; } if ( isset( $bits['fragment'] ) ) { $like[] = '#' . $bits['fragment']; } // Check for stray asterisks: asterisk only allowed at the start of the domain foreach ( $like as $likepart ) { if ( !( $likepart instanceof LikeMatch ) && strpos( $likepart, '*' ) !== false ) { return false; } } if ( !( $like[count( $like ) - 1] instanceof LikeMatch ) ) { // Add wildcard at the end if there isn't one already $like[] = $db->anyString(); } return $like; } /** * Filters an array returned by makeLikeArray(), removing everything past first * pattern placeholder. * * @param array $arr Array to filter * @return array Filtered array */ public static function keepOneWildcard( $arr ) { if ( !is_array( $arr ) ) { return $arr; } foreach ( $arr as $key => $value ) { if ( $value instanceof LikeMatch ) { return array_slice( $arr, 0, $key + 1 ); } } return $arr; } }