summaryrefslogtreecommitdiff
path: root/includes/LinkFilter.php
blob: 11b655956eba343371803fa824861c7d418d5404 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
<?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 Integer: 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.
	 *
	 * @param string $filterEntry domainparts
	 * @param $prot        String: protocol
	 * @return Array to be passed to DatabaseBase::buildLike() or false on error
	 */
	public static function makeLikeArray( $filterEntry, $prot = 'http://' ) {
		$db = wfGetDB( DB_MASTER );
		if ( substr( $filterEntry, 0, 2 ) == '*.' ) {
			$subdomains = true;
			$filterEntry = substr( $filterEntry, 2 );
			if ( $filterEntry == '' ) {
				// We don't want to make a clause that will match everything,
				// that could be dangerous
				return false;
			}
		} else {
			$subdomains = false;
		}
		// No stray asterisks, that could cause confusion
		// It's not simple or efficient to handle it properly so we don't
		// handle it at all.
		if ( strpos( $filterEntry, '*' ) !== false ) {
			return false;
		}
		$slash = strpos( $filterEntry, '/' );
		if ( $slash !== false ) {
			$path = substr( $filterEntry, $slash );
			$host = substr( $filterEntry, 0, $slash );
		} else {
			$path = '/';
			$host = $filterEntry;
		}
		// Reverse the labels in the hostname, convert to lower case
		// For emails reverse domainpart only
		if ( $prot == 'mailto:' && strpos( $host, '@' ) ) {
			// complete email address
			$mailparts = explode( '@', $host );
			$domainpart = strtolower( implode( '.', array_reverse( explode( '.', $mailparts[1] ) ) ) );
			$host = $domainpart . '@' . $mailparts[0];
			$like = array( "$prot$host", $db->anyString() );
		} elseif ( $prot == 'mailto:' ) {
			// domainpart of email address only. do not add '.'
			$host = strtolower( implode( '.', array_reverse( explode( '.', $host ) ) ) );
			$like = array( "$prot$host", $db->anyString() );
		} else {
			$host = strtolower( implode( '.', array_reverse( explode( '.', $host ) ) ) );
			if ( substr( $host, -1, 1 ) !== '.' ) {
				$host .= '.';
			}
			$like = array( "$prot$host" );

			if ( $subdomains ) {
				$like[] = $db->anyString();
			}
			if ( !$subdomains || $path !== '/' ) {
				$like[] = $path;
				$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;
	}
}