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