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<?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 Database::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 Database::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;
}
}
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