includes/IP.php

   1 <?php
   2 /**
   3  * Functions and constants to play with IP addresses and ranges
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  * @author Ashar Voultoiz <hashar at free dot fr>
  22  */
  23
  24 // Some regex definition to "play" with IP address and IP address blocks
  25
  26 // An IP is made of 4 bytes from x00 to xFF which is d0 to d255
  27 define( 'RE_IP_BYTE', '(25[0-5]|2[0-4][0-9]|1[0-9][0-9]|0?[0-9]?[0-9])' );
  28 define( 'RE_IP_ADD' , RE_IP_BYTE . '\.' . RE_IP_BYTE . '\.' . RE_IP_BYTE . '\.' . RE_IP_BYTE );
  29 // An IPv4 block is an IP address and a prefix (d1 to d32)
  30 define( 'RE_IP_PREFIX', '(3[0-2]|[12]?\d)' );
  31 define( 'RE_IP_BLOCK', RE_IP_ADD . '\/' . RE_IP_PREFIX );
  32 // For IPv6 canonicalization (NOT for strict validation; these are quite lax!)
  33 define( 'RE_IPV6_WORD', '([0-9A-Fa-f]{1,4})' );
  34 define( 'RE_IPV6_GAP', ':(?:0+:)*(?::(?:0+:)*)?' );
  35 define( 'RE_IPV6_V4_PREFIX', '0*' . RE_IPV6_GAP . '(?:ffff:)?' );
  36 // An IPv6 block is an IP address and a prefix (d1 to d128)
  37 define( 'RE_IPV6_PREFIX', '(12[0-8]|1[01][0-9]|[1-9]?\d)');
  38 // An IPv6 IP is made up of 8 octets. However abbreviations like "::" can be used.
  39 // This is lax! The number of colon groups is checked (1 to 7) but
  40 // the number of double colons is not validated (must be 0 to 1).
  41 define( 'RE_IPV6_ADD',
  42         '(' .
  43                 ':(:' . RE_IPV6_WORD . '){1,7}' . // starts with "::"
  44         '|' .
  45                 RE_IPV6_WORD . '(:{1,2}' . RE_IPV6_WORD . '){0,6}::' . // ends with "::"
  46         '|' .
  47                 RE_IPV6_WORD . '(:{1,2}' . RE_IPV6_WORD . '){1,7}' . // neither of the above
  48         ')'
  49 );
  50 define( 'RE_IPV6_BLOCK', RE_IPV6_ADD . '\/' . RE_IPV6_PREFIX );
  51 // This might be useful for regexps used elsewhere, matches any IPv6 or IPv6 address or network
  52 define( 'IP_ADDRESS_STRING',
  53         '(?:' .
  54                 RE_IP_ADD . '(\/' . RE_IP_PREFIX . '|)' . // IPv4
  55         '|' .
  56                 RE_IPV6_ADD . '(\/' . RE_IPV6_PREFIX . '|)' . // IPv6
  57         ')'
  58 );
  59
  60 /**
  61  * A collection of public static functions to play with IP address
  62  * and IP blocks.
  63  */
  64 class IP {
  65         /**
  66          * Given a string, determine if it as valid IP.
  67          * Note: Unlike isValid(), this looks for networks too.
  68          * @param $ip string possible IP address
  69          * @return string
  70          */
  71         public static function isIPAddress( $ip ) {
  72                 if ( !$ip ) {
  73                         return false;
  74                 }
  75                 if ( is_array( $ip ) ) {
  76                         throw new MWException( 'invalid value passed to ' . __METHOD__ );
  77                 }
  78                 return preg_match( '/^' . IP_ADDRESS_STRING . '$/', $ip )
  79                         && ( substr_count( $ip, '::' ) <= 1 ); // IPv6 IPs with 2+ "::" are ambiguous
  80         }
  81
  82         /**
  83          * Given a string, determine if it as valid IP in IPv6 only.
  84          * Note: Unlike isValid(), this looks for networks too.
  85          * @param $ip string possible IP address
  86          * @return string
  87          */
  88         public static function isIPv6( $ip ) {
  89                 if ( !$ip ) {
  90                         return false;
  91                 }
  92                 if ( is_array( $ip ) ) {
  93                         throw new MWException( 'invalid value passed to ' . __METHOD__ );
  94                 }
  95                 return preg_match( '/^' . RE_IPV6_ADD . '(\/' . RE_IPV6_PREFIX . '|)$/', $ip )
  96                         && ( substr_count( $ip, '::' ) <= 1 ); // IPv6 IPs with 2+ "::" are ambiguous
  97         }
  98
  99         /**
 100          * Given a string, determine if it as valid IP in IPv4 only.
 101          * Note: Unlike isValid(), this looks for networks too.
 102          * @param $ip string possible IP address
 103          * @return string
 104          */
 105         public static function isIPv4( $ip ) {
 106                 if ( !$ip ) {
 107                         return false;
 108                 }
 109                 return preg_match( '/^' . RE_IP_ADD . '(\/' . RE_IP_PREFIX . '|)$/', $ip );
 110         }
 111
 112         /**
 113          * Given an IP address in dotted-quad notation, returns an IPv6 octet.
 114          * See http://www.answers.com/topic/ipv4-compatible-address
 115          * IPs with the first 92 bits as zeros are reserved from IPv6
 116          * @param $ip quad-dotted IP address.
 117          * @return string
 118          */
 119         public static function IPv4toIPv6( $ip ) {
 120                 if ( !$ip ) {
 121                         return null;
 122                 }
 123                 // Convert only if needed
 124                 if ( self::isIPv6( $ip ) ) {
 125                         return $ip;
 126                 }
 127                 // IPv4 CIDRs
 128                 if ( strpos( $ip, '/' ) !== false ) {
 129                         $parts = explode( '/', $ip, 2 );
 130                         if ( count( $parts ) != 2 ) {
 131                                 return false;
 132                         }
 133                         list( $network, $bits ) = $parts;
 134                         $network = self::toUnsigned( $network );
 135                         if ( $network !== false && is_numeric( $bits ) && $bits >= 0 && $bits <= 32 ) {
 136                                 $bits += 96;
 137                                 return self::toOctet( $network ) . "/$bits";
 138                         } else {
 139                                 return false;
 140                         }
 141                 }
 142                 return self::toOctet( self::toUnsigned( $ip ) );
 143         }
 144
 145         /**
 146          * Given an IPv6 address in octet notation, returns an unsigned integer.
 147          * @param $ip octet ipv6 IP address.
 148          * @return string
 149          */
 150         public static function toUnsigned6( $ip ) {
 151                 if ( !$ip ) {
 152                         return null;
 153                 }
 154                 $ip = explode( ':', self::sanitizeIP( $ip ) );
 155                 $r_ip = '';
 156                 foreach ( $ip as $v ) {
 157                         $r_ip .= str_pad( $v, 4, 0, STR_PAD_LEFT );
 158                 }
 159                 $r_ip = wfBaseConvert( $r_ip, 16, 10 );
 160                 return $r_ip;
 161         }
 162
 163         /**
 164          * Given an IPv6 address in octet notation, returns the expanded octet.
 165          * IPv4 IPs will be trimmed, thats it...
 166          * @param $ip octet ipv6 IP address.
 167          * @return string
 168          */
 169         public static function sanitizeIP( $ip ) {
 170                 $ip = trim( $ip );
 171                 if ( $ip === '' ) {
 172                         return null;
 173                 }
 174                 // Trim and return IPv4 addresses
 175                 if ( self::isIPv4( $ip ) ) {
 176                         return $ip;
 177                 }
 178                 // Only IPv6 addresses can be expanded
 179                 if ( !self::isIPv6( $ip ) ) {
 180                         return $ip;
 181                 }
 182                 // Remove any whitespaces, convert to upper case
 183                 $ip = strtoupper( $ip );
 184                 // Expand zero abbreviations
 185                 $abbrevPos = strpos( $ip, '::' );
 186                 if ( $abbrevPos !== false ) {
 187                         // If the '::' is at the beginning...
 188                         if( $abbrevPos == 0 ) {
 189                                 $repeat = '0:';
 190                                 $extra = '';
 191                                 $pad = 9; // 7+2 (due to '::')
 192                         // If the '::' is at the end...
 193                         } elseif( $abbrevPos == ( strlen( $ip ) - 2 ) ) {
 194                                 $repeat = ':0';
 195                                 $extra = '';
 196                                 $pad = 9; // 7+2 (due to '::')
 197                         // If the '::' is at the end...
 198                         } else {
 199                                 $repeat = ':0';
 200                                 $extra = ':';
 201                                 $pad = 8; // 6+2 (due to '::')
 202                         }
 203                         $ip = str_replace( '::',
 204                                 str_repeat( $repeat, $pad - substr_count( $ip, ':' ) ) . $extra,
 205                                 $ip
 206                         );
 207                 }
 208                 // Remove leading zereos from each bloc as needed
 209                 $ip = preg_replace( '/(^|:)0+' . RE_IPV6_WORD . '/', '$1$2', $ip );
 210                 return $ip;
 211         }
 212
 213         /**
 214          * Given an unsigned integer, returns an IPv6 address in octet notation
 215          * @param $ip_int integer IP address.
 216          * @return string
 217          */
 218         public static function toOctet( $ip_int ) {
 219                 // Convert to padded uppercase hex
 220                 $ip_hex = wfBaseConvert( $ip_int, 10, 16, 32, false );
 221                 // Separate into 8 octets
 222                 $ip_oct = substr( $ip_hex, 0, 4 );
 223                 for ( $n = 1; $n < 8; $n++ ) {
 224                         $ip_oct .= ':' . substr( $ip_hex, 4 * $n, 4 );
 225                 }
 226                 // NO leading zeroes
 227                 $ip_oct = preg_replace( '/(^|:)0+' . RE_IPV6_WORD . '/', '$1$2', $ip_oct );
 228                 return $ip_oct;
 229         }
 230
 231         /**
 232          * Convert an IPv4 or IPv6 hexadecimal representation back to readable format
 233          * @param $hex string number, with "v6-" prefix if it is IPv6
 234          * @return string quad-dotted (IPv4) or octet notation (IPv6)
 235          */
 236         public static function formatHex( $hex ) {
 237                 if ( substr( $hex, 0, 3 ) == 'v6-' ) { // IPv6
 238                         return self::hexToOctet( substr( $hex, 3 ) );
 239                 } else { // IPv4
 240                         return self::hexToQuad( $hex );
 241                 }
 242         }
 243
 244         /**
 245          * Converts a hexadecimal number to an IPv6 address in octet notation
 246          * @param $ip_hex string hex IP
 247          * @return string (of format a:b:c:d:e:f:g:h)
 248          */
 249         public static function hexToOctet( $ip_hex ) {
 250                 // Convert to padded uppercase hex
 251                 $ip_hex = str_pad( strtoupper( $ip_hex ), 32, '0' );
 252                 // Separate into 8 octets
 253                 $ip_oct = substr( $ip_hex, 0, 4 );
 254                 for ( $n = 1; $n < 8; $n++ ) {
 255                         $ip_oct .= ':' . substr( $ip_hex, 4 * $n, 4 );
 256                 }
 257                 // NO leading zeroes
 258                 $ip_oct = preg_replace( '/(^|:)0+' . RE_IPV6_WORD . '/', '$1$2', $ip_oct );
 259                 return $ip_oct;
 260         }
 261
 262         /**
 263          * Converts a hexadecimal number to an IPv4 address in quad-dotted notation
 264          * @param $ip string Hex IP
 265          * @return string (of format a.b.c.d)
 266          */
 267         public static function hexToQuad( $ip ) {
 268                 $s = '';
 269                 for ( $i = 0; $i < 4; $i++ ) {
 270                         if ( $s !== '' ) {
 271                                 $s .= '.';
 272                         }
 273                         $s .= base_convert( substr( $ip, $i * 2, 2 ), 16, 10 );
 274                 }
 275                 return $s;
 276         }
 277
 278         /**
 279          * Convert a network specification in IPv6 CIDR notation to an
 280          * integer network and a number of bits
 281          * @return array(string, int)
 282          */
 283         public static function parseCIDR6( $range ) {
 284                 # Explode into <expanded IP,range>
 285                 $parts = explode( '/', IP::sanitizeIP( $range ), 2 );
 286                 if ( count( $parts ) != 2 ) {
 287                         return array( false, false );
 288                 }
 289                 list( $network, $bits ) = $parts;
 290                 $network = self::toUnsigned6( $network );
 291                 if ( $network !== false && is_numeric( $bits ) && $bits >= 0 && $bits <= 128 ) {
 292                         if ( $bits == 0 ) {
 293                                 $network = "0";
 294                         } else {
 295                                 # Native 32 bit functions WONT work here!!!
 296                                 # Convert to a padded binary number
 297                                 $network = wfBaseConvert( $network, 10, 2, 128 );
 298                                 # Truncate the last (128-$bits) bits and replace them with zeros
 299                                 $network = str_pad( substr( $network, 0, $bits ), 128, 0, STR_PAD_RIGHT );
 300                                 # Convert back to an integer
 301                                 $network = wfBaseConvert( $network, 2, 10 );
 302                         }
 303                 } else {
 304                         $network = false;
 305                         $bits = false;
 306                 }
 307                 return array( $network, (int)$bits );
 308         }
 309
 310         /**
 311          * Given a string range in a number of formats, return the start and end of
 312          * the range in hexadecimal. For IPv6.
 313          *
 314          * Formats are:
 315          *     2001:0db8:85a3::7344/96                                   CIDR
 316          *     2001:0db8:85a3::7344 - 2001:0db8:85a3::7344   Explicit range
 317          *     2001:0db8:85a3::7344/96                                   Single IP
 318          * @return array(string, int)
 319          */
 320         public static function parseRange6( $range ) {
 321                 # Expand any IPv6 IP
 322                 $range = IP::sanitizeIP( $range );
 323                 // CIDR notation...
 324                 if ( strpos( $range, '/' ) !== false ) {
 325                         list( $network, $bits ) = self::parseCIDR6( $range );
 326                         if ( $network === false ) {
 327                                 $start = $end = false;
 328                         } else {
 329                                 $start = wfBaseConvert( $network, 10, 16, 32, false );
 330                                 # Turn network to binary (again)
 331                                 $end = wfBaseConvert( $network, 10, 2, 128 );
 332                                 # Truncate the last (128-$bits) bits and replace them with ones
 333                                 $end = str_pad( substr( $end, 0, $bits ), 128, 1, STR_PAD_RIGHT );
 334                                 # Convert to hex
 335                                 $end = wfBaseConvert( $end, 2, 16, 32, false );
 336                                 # see toHex() comment
 337                                 $start = "v6-$start";
 338                                 $end = "v6-$end";
 339                         }
 340                 // Explicit range notation...
 341                 } elseif ( strpos( $range, '-' ) !== false ) {
 342                         list( $start, $end ) = array_map( 'trim', explode( '-', $range, 2 ) );
 343                         $start = self::toUnsigned6( $start );
 344                         $end = self::toUnsigned6( $end );
 345                         if ( $start > $end ) {
 346                                 $start = $end = false;
 347                         } else {
 348                                 $start = wfBaseConvert( $start, 10, 16, 32, false );
 349                                 $end = wfBaseConvert( $end, 10, 16, 32, false );
 350                         }
 351                         # see toHex() comment
 352                         $start = "v6-$start";
 353                         $end = "v6-$end";
 354                 } else {
 355                         # Single IP
 356                         $start = $end = self::toHex( $range );
 357                 }
 358                 if ( $start === false || $end === false ) {
 359                         return array( false, false );
 360                 } else {
 361                         return array( $start, $end );
 362                 }
 363         }
 364
 365         /**
 366          * Validate an IP address.
 367          * @return boolean True if it is valid.
 368          */
 369         public static function isValid( $ip ) {
 370                 return ( preg_match( '/^' . RE_IP_ADD . '$/', $ip ) || preg_match( '/^' . RE_IPV6_ADD . '$/', $ip ) );
 371         }
 372
 373         /**
 374          * Validate an IP Block.
 375          * @return boolean True if it is valid.
 376          */
 377         public static function isValidBlock( $ipblock ) {
 378                 return ( count( self::toArray( $ipblock ) ) == 1 + 5 );
 379         }
 380
 381         /**
 382          * Determine if an IP address really is an IP address, and if it is public,
 383          * i.e. not RFC 1918 or similar
 384          * Comes from ProxyTools.php
 385          */
 386         public static function isPublic( $ip ) {
 387                 $n = self::toUnsigned( $ip );
 388                 if ( !$n ) {
 389                         return false;
 390                 }
 391
 392                 // ip2long accepts incomplete addresses, as well as some addresses
 393                 // followed by garbage characters. Check that it's really valid.
 394                 if( $ip != long2ip( $n ) ) {
 395                         return false;
 396                 }
 397
 398                 static $privateRanges = false;
 399                 if ( !$privateRanges ) {
 400                         $privateRanges = array(
 401                                 array( '10.0.0.0',    '10.255.255.255' ),   # RFC 1918 (private)
 402                                 array( '172.16.0.0',  '172.31.255.255' ),   #     "
 403                                 array( '192.168.0.0', '192.168.255.255' ),  #     "
 404                                 array( '0.0.0.0',     '0.255.255.255' ),    # this network
 405                                 array( '127.0.0.0',   '127.255.255.255' ),  # loopback
 406                         );
 407                 }
 408
 409                 foreach ( $privateRanges as $r ) {
 410                         $start = self::toUnsigned( $r[0] );
 411                         $end = self::toUnsigned( $r[1] );
 412                         if ( $n >= $start && $n <= $end ) {
 413                                 return false;
 414                         }
 415                 }
 416                 return true;
 417         }
 418
 419         /**
 420          * Split out an IP block as an array of 4 bytes and a mask,
 421          * return false if it can't be determined
 422          *
 423          * @param $ipblock string A quad dotted/octet IP address
 424          * @return array
 425          */
 426         public static function toArray( $ipblock ) {
 427                 $matches = array();
 428                 if( preg_match( '/^' . RE_IP_ADD . '(?:\/(?:' . RE_IP_PREFIX . '))?' . '$/', $ipblock, $matches ) ) {
 429                         return $matches;
 430                 } elseif ( preg_match( '/^' . RE_IPV6_ADD . '(?:\/(?:' . RE_IPV6_PREFIX . '))?' . '$/', $ipblock, $matches ) ) {
 431                         return $matches;
 432                 } else {
 433                         return false;
 434                 }
 435         }
 436
 437         /**
 438          * Return a zero-padded hexadecimal representation of an IP address.
 439          *
 440          * Hexadecimal addresses are used because they can easily be extended to
 441          * IPv6 support. To separate the ranges, the return value from this
 442          * function for an IPv6 address will be prefixed with "v6-", a non-
 443          * hexadecimal string which sorts after the IPv4 addresses.
 444          *
 445          * @param $ip Quad dotted/octet IP address.
 446          * @return hexidecimal
 447          */
 448         public static function toHex( $ip ) {
 449                 $n = self::toUnsigned( $ip );
 450                 if ( $n !== false ) {
 451                         $n = self::isIPv6( $ip ) ? 'v6-' . wfBaseConvert( $n, 10, 16, 32, false ) : wfBaseConvert( $n, 10, 16, 8, false );
 452                 }
 453                 return $n;
 454         }
 455
 456         /**
 457          * Given an IP address in dotted-quad/octet notation, returns an unsigned integer.
 458          * Like ip2long() except that it actually works and has a consistent error return value.
 459          * Comes from ProxyTools.php
 460          * @param $ip Quad dotted IP address.
 461          * @return integer
 462          */
 463         public static function toUnsigned( $ip ) {
 464                 // Use IPv6 functions if needed
 465                 if ( self::isIPv6( $ip ) ) {
 466                         return self::toUnsigned6( $ip );
 467                 }
 468                 if ( $ip == '255.255.255.255' ) {
 469                         $n = -1;
 470                 } else {
 471                         $n = ip2long( $ip );
 472                         if ( $n == -1 || $n === false ) { # Return value on error depends on PHP version
 473                                 $n = false;
 474                         }
 475                 }
 476                 if ( $n < 0 ) {
 477                         $n += pow( 2, 32 );
 478                 }
 479                 return $n;
 480         }
 481
 482         /**
 483          * Convert a dotted-quad IP to a signed integer
 484          * Returns false on failure
 485          */
 486         public static function toSigned( $ip ) {
 487                 if ( $ip == '255.255.255.255' ) {
 488                         $n = -1;
 489                 } else {
 490                         $n = ip2long( $ip );
 491                         if ( $n == -1 ) {
 492                                 $n = false;
 493                         }
 494                 }
 495                 return $n;
 496         }
 497
 498         /**
 499          * Convert a network specification in CIDR notation to an integer network and a number of bits
 500          * @return array(int, int)
 501          */
 502         public static function parseCIDR( $range ) {
 503                 $parts = explode( '/', $range, 2 );
 504                 if ( count( $parts ) != 2 ) {
 505                         return array( false, false );
 506                 }
 507                 list( $network, $bits ) = $parts;
 508                 $network = self::toSigned( $network );
 509                 if ( $network !== false && is_numeric( $bits ) && $bits >= 0 && $bits <= 32 ) {
 510                         if ( $bits == 0 ) {
 511                                 $network = 0;
 512                         } else {
 513                                 $network &= ~( ( 1 << ( 32 - $bits ) ) - 1);
 514                         }
 515                         # Convert to unsigned
 516                         if ( $network < 0 ) {
 517                                 $network += pow( 2, 32 );
 518                         }
 519                 } else {
 520                         $network = false;
 521                         $bits = false;
 522                 }
 523                 return array( $network, $bits );
 524         }
 525
 526         /**
 527          * Given a string range in a number of formats, return the start and end of
 528          * the range in hexadecimal.
 529          *
 530          * Formats are:
 531          *     1.2.3.4/24          CIDR
 532          *     1.2.3.4 - 1.2.3.5   Explicit range
 533          *     1.2.3.4             Single IP
 534          *
 535          *     2001:0db8:85a3::7344/96                                   CIDR
 536          *     2001:0db8:85a3::7344 - 2001:0db8:85a3::7344   Explicit range
 537          *     2001:0db8:85a3::7344                                      Single IP
 538          * @return array(string, int)
 539          */
 540         public static function parseRange( $range ) {
 541                 // Use IPv6 functions if needed
 542                 if ( self::isIPv6( $range ) ) {
 543                         return self::parseRange6( $range );
 544                 }
 545                 if ( strpos( $range, '/' ) !== false ) {
 546                         # CIDR
 547                         list( $network, $bits ) = self::parseCIDR( $range );
 548                         if ( $network === false ) {
 549                                 $start = $end = false;
 550                         } else {
 551                                 $start = sprintf( '%08X', $network );
 552                                 $end = sprintf( '%08X', $network + pow( 2, ( 32 - $bits ) ) - 1 );
 553                         }
 554                 } elseif ( strpos( $range, '-' ) !== false ) {
 555                         # Explicit range
 556                         list( $start, $end ) = array_map( 'trim', explode( '-', $range, 2 ) );
 557                         if( self::isIPAddress( $start ) && self::isIPAddress( $end ) ) {
 558                                 $start = self::toUnsigned( $start );
 559                                 $end = self::toUnsigned( $end );
 560                                 if ( $start > $end ) {
 561                                         $start = $end = false;
 562                                 } else {
 563                                         $start = sprintf( '%08X', $start );
 564                                         $end = sprintf( '%08X', $end );
 565                                 }
 566                         } else {
 567                                 $start = $end = false;
 568                         }
 569                 } else {
 570                         # Single IP
 571                         $start = $end = self::toHex( $range );
 572                 }
 573                 if ( $start === false || $end === false ) {
 574                         return array( false, false );
 575                 } else {
 576                         return array( $start, $end );
 577                 }
 578         }
 579
 580         /**
 581          * Determine if a given IPv4/IPv6 address is in a given CIDR network
 582          * @param $addr The address to check against the given range.
 583          * @param $range The range to check the given address against.
 584          * @return bool Whether or not the given address is in the given range.
 585          */
 586         public static function isInRange( $addr, $range ) {
 587                 // Convert to IPv6 if needed
 588                 $hexIP = self::toHex( $addr );
 589                 list( $start, $end ) = self::parseRange( $range );
 590                 return ( strcmp( $hexIP, $start ) >= 0 &&
 591                         strcmp( $hexIP, $end ) <= 0 );
 592         }
 593
 594         /**
 595          * Convert some unusual representations of IPv4 addresses to their
 596          * canonical dotted quad representation.
 597          *
 598          * This currently only checks a few IPV4-to-IPv6 related cases.  More
 599          * unusual representations may be added later.
 600          *
 601          * @param $addr something that might be an IP address
 602          * @return valid dotted quad IPv4 address or null
 603          */
 604         public static function canonicalize( $addr ) {
 605                 if ( self::isValid( $addr ) ) {
 606                         return $addr;
 607                 }
 608
 609                 // Turn mapped addresses from ::ce:ffff:1.2.3.4 to 1.2.3.4
 610                 if ( strpos( $addr, ':' ) !== false && strpos( $addr, '.' ) !== false ) {
 611                         $addr = substr( $addr, strrpos( $addr, ':' ) + 1 );
 612                         if( self::isIPv4( $addr ) ) {
 613                                 return $addr;
 614                         }
 615                 }
 616
 617                 // IPv6 loopback address
 618                 $m = array();
 619                 if ( preg_match( '/^0*' . RE_IPV6_GAP . '1$/', $addr, $m ) ) {
 620                         return '127.0.0.1';
 621                 }
 622
 623                 // IPv4-mapped and IPv4-compatible IPv6 addresses
 624                 if ( preg_match( '/^' . RE_IPV6_V4_PREFIX . '(' . RE_IP_ADD . ')$/i', $addr, $m ) ) {
 625                         return $m[1];
 626                 }
 627                 if ( preg_match( '/^' . RE_IPV6_V4_PREFIX . RE_IPV6_WORD . ':' . RE_IPV6_WORD . '$/i', $addr, $m ) ) {
 628                         return long2ip( ( hexdec( $m[1] ) << 16 ) + hexdec( $m[2] ) );
 629                 }
 630
 631                 return null;  // give up
 632         }
 633 }