includes/libs/IPSet.php

   1 <?php
   2 /**
   3  * This program is free software; you can redistribute it and/or modify
   4  * it under the terms of the GNU General Public License as published by
   5  * the Free Software Foundation; either version 2 of the License, or
   6  * (at your option) any later version.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  11  * GNU General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public License along
  14  * with this program; if not, write to the Free Software Foundation, Inc.,
  15  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  16  * http://www.gnu.org/copyleft/gpl.html
  17  *
  18  * @file
  19  * @author Brandon Black <blblack@gmail.com>
  20  */
  21
  22 /**
  23  * Matches IP addresses against a set of CIDR specifications
  24  *
  25  * Usage:
  26  *   // At startup, calculate the optimized data structure for the set:
  27  *   $ipset = new IPSet( $wgSquidServersNoPurge );
  28  *   // runtime check against cached set (returns bool):
  29  *   $allowme = $ipset->match( $ip );
  30  *
  31  * In rough benchmarking, this takes about 80% more time than
  32  * in_array() checks on a short (a couple hundred at most) array
  33  * of addresses.  It's fast either way at those levels, though,
  34  * and IPSet would scale better than in_array if the array were
  35  * much larger.
  36  *
  37  * For mixed-family CIDR sets, however, this code gives well over
  38  * 100x speedup vs iterating IP::isInRange() over an array
  39  * of CIDR specs.
  40  *
  41  * The basic implementation is two separate binary trees
  42  * (IPv4 and IPv6) as nested php arrays with keys named 0 and 1.
  43  * The values false and true are terminal match-fail and match-success,
  44  * otherwise the value is a deeper node in the tree.
  45  *
  46  * A simple depth-compression scheme is also implemented: whole-byte
  47  * tree compression at whole-byte boundaries only, where no branching
  48  * occurs during that whole byte of depth.  A compressed node has
  49  * keys 'comp' (the byte to compare) and 'next' (the next node to
  50  * recurse into if 'comp' matched successfully).
  51  *
  52  * For example, given these inputs:
  53  * 25.0.0.0/9
  54  * 25.192.0.0/10
  55  *
  56  * The v4 tree would look like:
  57  * root4 => array(
  58  *     'comp' => 25,
  59  *     'next' => array(
  60  *         0 => true,
  61  *         1 => array(
  62  *             0 => false,
  63  *             1 => true,
  64  *         ),
  65  *     ),
  66  * );
  67  *
  68  * (multi-byte compression nodes were attempted as well, but were
  69  * a net loss in my test scenarios due to additional match complexity)
  70  *
  71  * @since 1.24
  72  */
  73 class IPSet {
  74         /** @var array $root4: the root of the IPv4 matching tree */
  75         private $root4 = array( false, false );
  76
  77         /** @var array $root6: the root of the IPv6 matching tree */
  78         private $root6 = array( false, false );
  79
  80         /**
  81          * __construct() instantiate the object from an array of CIDR specs
  82          *
  83          * @param array $cfg array of IPv[46] CIDR specs as strings
  84          * @return IPSet new IPSet object
  85          *
  86          * Invalid input network/mask values in $cfg will result in issuing
  87          * E_WARNING and/or E_USER_WARNING and the bad values being ignored.
  88          */
  89         public function __construct( array $cfg ) {
  90                 foreach ( $cfg as $cidr ) {
  91                         $this->addCidr( $cidr );
  92                 }
  93
  94                 self::recOptimize( $this->root4 );
  95                 self::recCompress( $this->root4, 0, 24 );
  96                 self::recOptimize( $this->root6 );
  97                 self::recCompress( $this->root6, 0, 120 );
  98         }
  99
 100         /**
 101          * Add a single CIDR spec to the internal matching trees
 102          *
 103          * @param string $cidr string CIDR spec, IPv[46], optional /mask (def all-1's)
 104          */
 105         private function addCidr( $cidr ) {
 106                 // v4 or v6 check
 107                 if ( strpos( $cidr, ':' ) === false ) {
 108                         $node =& $this->root4;
 109                         $defMask = '32';
 110                 } else {
 111                         $node =& $this->root6;
 112                         $defMask = '128';
 113                 }
 114
 115                 // Default to all-1's mask if no netmask in the input
 116                 if ( strpos( $cidr, '/' ) === false ) {
 117                         $net = $cidr;
 118                         $mask = $defMask;
 119                 } else {
 120                         list( $net, $mask ) = explode( '/', $cidr, 2 );
 121                         if ( !ctype_digit( $mask ) || intval( $mask ) > $defMask ) {
 122                                 trigger_error( "IPSet: Bad mask '$mask' from '$cidr', ignored", E_USER_WARNING );
 123                                 return;
 124                         }
 125                 }
 126                 $mask = intval( $mask ); // explicit integer convert, checked above
 127
 128                 // convert $net to an array of integer bytes, length 4 or 16:
 129                 $raw = inet_pton( $net );
 130                 if ( $raw === false ) {
 131                         return; // inet_pton() sends an E_WARNING for us
 132                 }
 133                 $rawOrd = array_map( 'ord', str_split( $raw ) );
 134
 135                 // special-case: zero mask overwrites the whole tree with a pair of terminal successes
 136                 if ( $mask == 0 ) {
 137                         $node = array( true, true );
 138                         return;
 139                 }
 140
 141                 // iterate the bits of the address while walking the tree structure for inserts
 142                 $curBit = 0;
 143                 while ( 1 ) {
 144                         $maskShift = 7 - ( $curBit & 7 );
 145                         $node =& $node[( $rawOrd[$curBit >> 3] & ( 1 << $maskShift ) ) >> $maskShift];
 146                         ++$curBit;
 147                         if ( $node === true ) {
 148                                 // already added a larger supernet, no need to go deeper
 149                                 return;
 150                         } elseif ( $curBit == $mask ) {
 151                                 // this may wipe out deeper subnets from earlier
 152                                 $node = true;
 153                                 return;
 154                         } elseif ( $node === false ) {
 155                                 // create new subarray to go deeper
 156                                 $node = array( false, false );
 157                         }
 158                 }
 159         }
 160
 161         /**
 162          * Match an IP address against the set
 163          *
 164          * @param string $ip string IPv[46] address
 165          * @return bool true is match success, false is match failure
 166          *
 167          * If $ip is unparseable, inet_pton may issue an E_WARNING to that effect
 168          */
 169         public function match( $ip ) {
 170                 $raw = inet_pton( $ip );
 171                 if ( $raw === false ) {
 172                         return false; // inet_pton() sends an E_WARNING for us
 173                 }
 174
 175                 $rawOrd = array_map( 'ord', str_split( $raw ) );
 176                 if ( count( $rawOrd ) == 4 ) {
 177                         $node =& $this->root4;
 178                 } else {
 179                         $node =& $this->root6;
 180                 }
 181
 182                 $curBit = 0;
 183                 while ( 1 ) {
 184                         if ( isset( $node['comp'] ) ) {
 185                                 // compressed node, matches 1 whole byte on a byte boundary
 186                                 if ( $rawOrd[$curBit >> 3] != $node['comp'] ) {
 187                                         return false;
 188                                 }
 189                                 $curBit += 8;
 190                                 $node =& $node['next'];
 191                         } else {
 192                                 // uncompressed node, walk in the correct direction for the current bit-value
 193                                 $maskShift = 7 - ( $curBit & 7 );
 194                                 $node =& $node[( $rawOrd[$curBit >> 3] & ( 1 << $maskShift ) ) >> $maskShift];
 195                                 ++$curBit;
 196                         }
 197
 198                         if ( $node === true || $node === false ) {
 199                                 return $node;
 200                         }
 201                 }
 202         }
 203
 204         /**
 205          * Recursively merges adjacent nets into larger supernets
 206          *
 207          * @param array &$node Tree node to optimize, by-reference
 208          *
 209          *  e.g.: 8.0.0.0/8 + 9.0.0.0/8 -> 8.0.0.0/7
 210          */
 211         private static function recOptimize( &$node ) {
 212                 if ( $node[0] !== false && $node[0] !== true && self::recOptimize( $node[0] ) ) {
 213                         $node[0] = true;
 214                 }
 215                 if ( $node[1] !== false && $node[1] !== true && self::recOptimize( $node[1] ) ) {
 216                         $node[1] = true;
 217                 }
 218                 if ( $node[0] === true && $node[1] === true ) {
 219                         return true;
 220                 }
 221                 return false;
 222         }
 223
 224         /**
 225          * Recursively compresses a tree
 226          *
 227          * @param array &$node Tree node to compress, by-reference
 228          * @param integer $curBit current depth in the tree
 229          * @param integer $maxCompStart maximum depth at which compression can start, family-specific
 230          *
 231          * This is a very simplistic compression scheme: if we go through a whole
 232          * byte of address starting at a byte boundary with no real branching
 233          * other than immediate false-vs-(node|true), compress that subtree down to a single
 234          * byte-matching node.
 235          * The $maxCompStart check elides recursing the final 7 levels of depth (family-dependent)
 236          */
 237         private static function recCompress( &$node, $curBit, $maxCompStart ) {
 238                 if ( !( $curBit & 7 ) ) { // byte boundary, check for depth-8 single path(s)
 239                         $byte = 0;
 240                         $cnode =& $node;
 241                         $i = 8;
 242                         while ( $i-- ) {
 243                                 if ( $cnode[0] === false ) {
 244                                         $byte |= 1 << $i;
 245                                         $cnode =& $cnode[1];
 246                                 } elseif ( $cnode[1] === false ) {
 247                                         $cnode =& $cnode[0];
 248                                 } else {
 249                                         // partial-byte branching, give up
 250                                         break;
 251                                 }
 252                         }
 253                         if ( $i == -1 ) { // means we did not exit the while() via break
 254                                 $node = array(
 255                                         'comp' => $byte,
 256                                         'next' => &$cnode,
 257                                 );
 258                                 $curBit += 8;
 259                                 if ( $cnode !== true ) {
 260                                         self::recCompress( $cnode, $curBit, $maxCompStart );
 261                                 }
 262                                 return;
 263                         }
 264                 }
 265
 266                 ++$curBit;
 267                 if ( $curBit <= $maxCompStart ) {
 268                         if ( $node[0] !== false && $node[0] !== true ) {
 269                                 self::recCompress( $node[0], $curBit, $maxCompStart );
 270                         }
 271                         if ( $node[1] !== false && $node[1] !== true ) {
 272                                 self::recCompress( $node[1], $curBit, $maxCompStart );
 273                         }
 274                 }
 275         }
 276 }