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>, Aaron Schulz
  22  */
  23
  24 // Some regex definition to "play" with IP address and IP address blocks
  25
  26 // An IPv4 address 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
  33 // An IPv6 address is made up of 8 words (each x0000 to xFFFF).
  34 // However, the "::" abbreviation can be used on consecutive x0000 words.
  35 define( 'RE_IPV6_WORD', '([0-9A-Fa-f]{1,4})' );
  36 define( 'RE_IPV6_PREFIX', '(12[0-8]|1[01][0-9]|[1-9]?\d)');
  37 define( 'RE_IPV6_ADD',
  38         '(?:' . // starts with "::" (including "::")
  39                 ':(?::|(?::' . RE_IPV6_WORD . '){1,7})' .
  40         '|' . // ends with "::" (except "::")
  41                 RE_IPV6_WORD . '(?::' . RE_IPV6_WORD . '){0,6}::' .
  42         '|' . // contains no "::"
  43                 RE_IPV6_WORD . '(?::' . RE_IPV6_WORD . '){7}' .
  44         '|' . // contains one "::" in the middle and 2 words
  45                 RE_IPV6_WORD . '::' . RE_IPV6_WORD .
  46         '|' . // contains one "::" in the middle and 3+ words (awkward regex for PCRE 4.0+)
  47                 RE_IPV6_WORD . '(?::(?P<abn>:(?P<iabn>))?' . RE_IPV6_WORD . '(?!:(?P=abn))){1,5}' .
  48                         ':' . RE_IPV6_WORD . '(?P=iabn)' .
  49                 // NOTE: (?!(?P=abn)) fails iff "::" used twice; (?P=iabn) passes iff a "::" was found.
  50                 // RegExp (PCRE 7.2+ only) for last 2 cases that allows easy regex concatenation:
  51                 #RE_IPV6_WORD . '(?::((?(-1)|:))?' . RE_IPV6_WORD . '){1,6}(?(-2)|^)' .
  52         ')'
  53 );
  54 // An IPv6 block is an IP address and a prefix (d1 to d128)
  55 define( 'RE_IPV6_BLOCK', RE_IPV6_ADD . '\/' . RE_IPV6_PREFIX );
  56 // For IPv6 canonicalization (NOT for strict validation; these are quite lax!)
  57 define( 'RE_IPV6_GAP', ':(?:0+:)*(?::(?:0+:)*)?' );
  58 define( 'RE_IPV6_V4_PREFIX', '0*' . RE_IPV6_GAP . '(?:ffff:)?' );
  59
  60 // This might be useful for regexps used elsewhere, matches any IPv6 or IPv6 address or network
  61 define( 'IP_ADDRESS_STRING',
  62         '(?:' .
  63                 RE_IP_ADD . '(?:\/' . RE_IP_PREFIX . ')?' . // IPv4
  64         '|' .
  65                 RE_IPV6_ADD . '(?:\/' . RE_IPV6_PREFIX . ')?' . // IPv6
  66         ')'
  67 );
  68
  69 /**
  70  * A collection of public static functions to play with IP address
  71  * and IP blocks.
  72  */
  73 class IP {
  74         /**
  75          * Determine if a string is as valid IP address or network (CIDR prefix).
  76          * SIIT IPv4-translated addresses are rejected.
  77          * Note: canonicalize() tries to convert translated addresses to IPv4.
  78          *
  79          * @param $ip String: possible IP address
  80          * @return Boolean
  81          */
  82         public static function isIPAddress( $ip ) {
  83                 return (bool)preg_match( '/^' . IP_ADDRESS_STRING . '$/', $ip );
  84         }
  85
  86         /**
  87          * Given a string, determine if it as valid IP in IPv6 only.
  88          * Note: Unlike isValid(), this looks for networks too.
  89          *
  90          * @param $ip String: possible IP address
  91          * @return Boolean
  92          */
  93         public static function isIPv6( $ip ) {
  94                 return (bool)preg_match( '/^' . RE_IPV6_ADD . '(?:\/' . RE_IPV6_PREFIX . ')?$/', $ip );
  95         }
  96
  97         /**
  98          * Given a string, determine if it as valid IP in IPv4 only.
  99          * Note: Unlike isValid(), this looks for networks too.
 100          *
 101          * @param $ip String: possible IP address
 102          * @return Boolean
 103          */
 104         public static function isIPv4( $ip ) {
 105                 return (bool)preg_match( '/^' . RE_IP_ADD . '(?:\/' . RE_IP_PREFIX . ')?$/', $ip );
 106         }
 107
 108         /**
 109          * Validate an IP address. Ranges are NOT considered valid.
 110          * SIIT IPv4-translated addresses are rejected.
 111          * Note: canonicalize() tries to convert translated addresses to IPv4.
 112          *
 113          * @param $ip String
 114          * @return Boolean: True if it is valid.
 115          */
 116         public static function isValid( $ip ) {
 117                 return ( preg_match( '/^' . RE_IP_ADD . '$/', $ip )
 118                         || preg_match( '/^' . RE_IPV6_ADD . '$/', $ip ) );
 119         }
 120
 121         /**
 122          * Validate an IP Block (valid address WITH a valid prefix).
 123          * SIIT IPv4-translated addresses are rejected.
 124          * Note: canonicalize() tries to convert translated addresses to IPv4.
 125          *
 126          * @param $ipblock String
 127          * @return Boolean: True if it is valid.
 128          */
 129         public static function isValidBlock( $ipblock ) {
 130                 return ( preg_match( '/^' . RE_IPV6_BLOCK . '$/', $ipblock )
 131                         || preg_match( '/^' . RE_IP_BLOCK . '$/', $ipblock ) );
 132         }
 133
 134         /**
 135          * Convert an IP into a nice standard form.
 136          * IPv6 addresses in octet notation are expanded to 8 words.
 137          * IPv4 addresses are just trimmed.
 138          *
 139          * @param $ip String: IP address in quad or octet form (CIDR or not).
 140          * @return String
 141          */
 142         public static function sanitizeIP( $ip ) {
 143                 $ip = trim( $ip );
 144                 if ( $ip === '' ) {
 145                         return null;
 146                 }
 147                 if ( self::isIPv4( $ip ) || !self::isIPv6( $ip ) ) {
 148                         return $ip; // nothing else to do for IPv4 addresses or invalid ones
 149                 }
 150                 // Remove any whitespaces, convert to upper case
 151                 $ip = strtoupper( $ip );
 152                 // Expand zero abbreviations
 153                 $abbrevPos = strpos( $ip, '::' );
 154                 if ( $abbrevPos !== false ) {
 155                         // We know this is valid IPv6. Find the last index of the
 156                         // address before any CIDR number (e.g. "a:b:c::/24").
 157                         $CIDRStart = strpos( $ip, "/" );
 158                         $addressEnd = ( $CIDRStart !== false )
 159                                 ? $CIDRStart - 1
 160                                 : strlen( $ip ) - 1;
 161                         // If the '::' is at the beginning...
 162                         if ( $abbrevPos == 0 ) {
 163                                 $repeat = '0:';
 164                                 $extra = ( $ip == '::' ) ? '0' : ''; // for the address '::'
 165                                 $pad = 9; // 7+2 (due to '::')
 166                         // If the '::' is at the end...
 167                         } elseif ( $abbrevPos == ( $addressEnd - 1 ) ) {
 168                                 $repeat = ':0';
 169                                 $extra = '';
 170                                 $pad = 9; // 7+2 (due to '::')
 171                         // If the '::' is in the middle...
 172                         } else {
 173                                 $repeat = ':0';
 174                                 $extra = ':';
 175                                 $pad = 8; // 6+2 (due to '::')
 176                         }
 177                         $ip = str_replace( '::',
 178                                 str_repeat( $repeat, $pad - substr_count( $ip, ':' ) ) . $extra,
 179                                 $ip
 180                         );
 181                 }
 182                 // Remove leading zereos from each bloc as needed
 183                 $ip = preg_replace( '/(^|:)0+(' . RE_IPV6_WORD . ')/', '$1$2', $ip );
 184                 return $ip;
 185         }
 186
 187         /**
 188          * Given an unsigned integer, returns an IPv6 address in octet notation
 189          *
 190          * @param $ip_int String: IP address.
 191          * @return String
 192          */
 193         public static function toOctet( $ip_int ) {
 194                 return self::hexToOctet( wfBaseConvert( $ip_int, 10, 16, 32, false ) );
 195         }
 196
 197         /**
 198          * Convert an IPv4 or IPv6 hexadecimal representation back to readable format
 199          *
 200          * @param $hex String: number, with "v6-" prefix if it is IPv6
 201          * @return String: quad-dotted (IPv4) or octet notation (IPv6)
 202          */
 203         public static function formatHex( $hex ) {
 204                 if ( substr( $hex, 0, 3 ) == 'v6-' ) { // IPv6
 205                         return self::hexToOctet( substr( $hex, 3 ) );
 206                 } else { // IPv4
 207                         return self::hexToQuad( $hex );
 208                 }
 209         }
 210
 211         /**
 212          * Converts a hexadecimal number to an IPv6 address in octet notation
 213          *
 214          * @param $ip_hex String: pure hex (no v6- prefix)
 215          * @return String (of format a:b:c:d:e:f:g:h)
 216          */
 217         public static function hexToOctet( $ip_hex ) {
 218                 // Pad hex to 32 chars (128 bits)
 219                 $ip_hex = str_pad( strtoupper( $ip_hex ), 32, '0', STR_PAD_LEFT );
 220                 // Separate into 8 words
 221                 $ip_oct = substr( $ip_hex, 0, 4 );
 222                 for ( $n = 1; $n < 8; $n++ ) {
 223                         $ip_oct .= ':' . substr( $ip_hex, 4 * $n, 4 );
 224                 }
 225                 // NO leading zeroes
 226                 $ip_oct = preg_replace( '/(^|:)0+(' . RE_IPV6_WORD . ')/', '$1$2', $ip_oct );
 227                 return $ip_oct;
 228         }
 229
 230         /**
 231          * Converts a hexadecimal number to an IPv4 address in quad-dotted notation
 232          *
 233          * @param $ip_hex String: pure hex
 234          * @return String (of format a.b.c.d)
 235          */
 236         public static function hexToQuad( $ip_hex ) {
 237                 // Pad hex to 8 chars (32 bits)
 238                 $ip_hex = str_pad( strtoupper( $ip_hex ), 8, '0', STR_PAD_LEFT );
 239                 // Separate into four quads
 240                 $s = '';
 241                 for ( $i = 0; $i < 4; $i++ ) {
 242                         if ( $s !== '' ) {
 243                                 $s .= '.';
 244                         }
 245                         $s .= base_convert( substr( $ip_hex, $i * 2, 2 ), 16, 10 );
 246                 }
 247                 return $s;
 248         }
 249
 250         /**
 251          * Determine if an IP address really is an IP address, and if it is public,
 252          * i.e. not RFC 1918 or similar
 253          * Comes from ProxyTools.php
 254          *
 255          * @param $ip String
 256          * @return Boolean
 257          */
 258         public static function isPublic( $ip ) {
 259                 if ( self::isIPv6( $ip ) ) {
 260                         return self::isPublic6( $ip );
 261                 }
 262                 $n = self::toUnsigned( $ip );
 263                 if ( !$n ) {
 264                         return false;
 265                 }
 266
 267                 // ip2long accepts incomplete addresses, as well as some addresses
 268                 // followed by garbage characters. Check that it's really valid.
 269                 if ( $ip != long2ip( $n ) ) {
 270                         return false;
 271                 }
 272
 273                 static $privateRanges = false;
 274                 if ( !$privateRanges ) {
 275                         $privateRanges = array(
 276                                 array( '10.0.0.0',    '10.255.255.255' ),   # RFC 1918 (private)
 277                                 array( '172.16.0.0',  '172.31.255.255' ),   #     "
 278                                 array( '192.168.0.0', '192.168.255.255' ),  #     "
 279                                 array( '0.0.0.0',     '0.255.255.255' ),    # this network
 280                                 array( '127.0.0.0',   '127.255.255.255' ),  # loopback
 281                         );
 282                 }
 283
 284                 foreach ( $privateRanges as $r ) {
 285                         $start = self::toUnsigned( $r[0] );
 286                         $end = self::toUnsigned( $r[1] );
 287                         if ( $n >= $start && $n <= $end ) {
 288                                 return false;
 289                         }
 290                 }
 291                 return true;
 292         }
 293
 294         /**
 295          * Determine if an IPv6 address really is an IP address, and if it is public,
 296          * i.e. not RFC 4193 or similar
 297          *
 298          * @param $ip String
 299          * @return Boolean
 300          */
 301         private static function isPublic6( $ip ) {
 302                 static $privateRanges = false;
 303                 if ( !$privateRanges ) {
 304                         $privateRanges = array(
 305                                 array( 'fc::', 'fdff:ffff:ffff:ffff:ffff:ffff:ffff:ffff' ), # RFC 4193 (local)
 306                                 array( '0:0:0:0:0:0:0:1', '0:0:0:0:0:0:0:1' ), # loopback
 307                         );
 308                 }
 309                 $n = self::toHex( $ip );
 310                 foreach ( $privateRanges as $r ) {
 311                         $start = self::toHex( $r[0] );
 312                         $end = self::toHex( $r[1] );
 313                         if ( $n >= $start && $n <= $end ) {
 314                                 return false;
 315                         }
 316                 }
 317                 return true;
 318         }
 319
 320         /**
 321          * Return a zero-padded upper case hexadecimal representation of an IP address.
 322          *
 323          * Hexadecimal addresses are used because they can easily be extended to
 324          * IPv6 support. To separate the ranges, the return value from this
 325          * function for an IPv6 address will be prefixed with "v6-", a non-
 326          * hexadecimal string which sorts after the IPv4 addresses.
 327          *
 328          * @param $ip String: quad dotted/octet IP address.
 329          * @return String
 330          */
 331         public static function toHex( $ip ) {
 332                 if ( self::isIPv6( $ip ) ) {
 333                         $n = 'v6-' . self::IPv6ToRawHex( $ip );
 334                 } else {
 335                         $n = self::toUnsigned( $ip );
 336                         if ( $n !== false ) {
 337                                 $n = wfBaseConvert( $n, 10, 16, 8, false );
 338                         }
 339                 }
 340                 return $n;
 341         }
 342
 343         /**
 344          * Given an IPv6 address in octet notation, returns a pure hex string.
 345          *
 346          * @param $ip String: octet ipv6 IP address.
 347          * @return String: pure hex (uppercase)
 348          */
 349         private static function IPv6ToRawHex( $ip ) {
 350                 $ip = self::sanitizeIP( $ip );
 351                 if ( !$ip ) {
 352                         return null;
 353                 }
 354                 $r_ip = '';
 355                 foreach ( explode( ':', $ip ) as $v ) {
 356                         $r_ip .= str_pad( $v, 4, 0, STR_PAD_LEFT );
 357                 }
 358                 return $r_ip;
 359         }
 360
 361         /**
 362          * Given an IP address in dotted-quad/octet notation, returns an unsigned integer.
 363          * Like ip2long() except that it actually works and has a consistent error return value.
 364          * Comes from ProxyTools.php
 365          *
 366          * @param $ip String: quad dotted IP address.
 367          * @return Mixed: string/int/false
 368          */
 369         public static function toUnsigned( $ip ) {
 370                 if ( self::isIPv6( $ip ) ) {
 371                         $n = self::toUnsigned6( $ip );
 372                 } else {
 373                         $n = ip2long( $ip );
 374                         if ( $n < 0 ) {
 375                                 $n += pow( 2, 32 );
 376                         }
 377                 }
 378                 return $n;
 379         }
 380
 381         private static function toUnsigned6( $ip ) {
 382                 return wfBaseConvert( self::IPv6ToRawHex( $ip ), 16, 10 );
 383         }
 384
 385         /**
 386          * Convert a network specification in CIDR notation
 387          * to an integer network and a number of bits
 388          *
 389          * @param $range String: IP with CIDR prefix
 390          * @return array(int or string, int)
 391          */
 392         public static function parseCIDR( $range ) {
 393                 if ( self::isIPv6( $range ) ) {
 394                         return self::parseCIDR6( $range );
 395                 }
 396                 $parts = explode( '/', $range, 2 );
 397                 if ( count( $parts ) != 2 ) {
 398                         return array( false, false );
 399                 }
 400                 list( $network, $bits ) = $parts;
 401                 $network = ip2long( $network );
 402                 if ( $network !== false && is_numeric( $bits ) && $bits >= 0 && $bits <= 32 ) {
 403                         if ( $bits == 0 ) {
 404                                 $network = 0;
 405                         } else {
 406                                 $network &= ~( ( 1 << ( 32 - $bits ) ) - 1);
 407                         }
 408                         # Convert to unsigned
 409                         if ( $network < 0 ) {
 410                                 $network += pow( 2, 32 );
 411                         }
 412                 } else {
 413                         $network = false;
 414                         $bits = false;
 415                 }
 416                 return array( $network, $bits );
 417         }
 418
 419         /**
 420          * Given a string range in a number of formats,
 421          * return the start and end of the range in hexadecimal.
 422          *
 423          * Formats are:
 424          *     1.2.3.4/24          CIDR
 425          *     1.2.3.4 - 1.2.3.5   Explicit range
 426          *     1.2.3.4             Single IP
 427          *
 428          *     2001:0db8:85a3::7344/96                                   CIDR
 429          *     2001:0db8:85a3::7344 - 2001:0db8:85a3::7344   Explicit range
 430          *     2001:0db8:85a3::7344                                      Single IP
 431          * @param $range String: IP range
 432          * @return array(string, string)
 433          */
 434         public static function parseRange( $range ) {
 435                 // CIDR notation
 436                 if ( strpos( $range, '/' ) !== false ) {
 437                         if ( self::isIPv6( $range ) ) {
 438                                 return self::parseRange6( $range );
 439                         }
 440                         list( $network, $bits ) = self::parseCIDR( $range );
 441                         if ( $network === false ) {
 442                                 $start = $end = false;
 443                         } else {
 444                                 $start = sprintf( '%08X', $network );
 445                                 $end = sprintf( '%08X', $network + pow( 2, ( 32 - $bits ) ) - 1 );
 446                         }
 447                 // Explicit range
 448                 } elseif ( strpos( $range, '-' ) !== false ) {
 449                         list( $start, $end ) = array_map( 'trim', explode( '-', $range, 2 ) );
 450                         if ( self::isIPv6( $start ) && self::isIPv6( $end ) ) {
 451                                 return self::parseRange6( $range );
 452                         }
 453                         if ( self::isIPv4( $start ) && self::isIPv4( $end ) ) {
 454                                 $start = self::toUnsigned( $start );
 455                                 $end = self::toUnsigned( $end );
 456                                 if ( $start > $end ) {
 457                                         $start = $end = false;
 458                                 } else {
 459                                         $start = sprintf( '%08X', $start );
 460                                         $end = sprintf( '%08X', $end );
 461                                 }
 462                         } else {
 463                                 $start = $end = false;
 464                         }
 465                 } else {
 466                         # Single IP
 467                         $start = $end = self::toHex( $range );
 468                 }
 469                 if ( $start === false || $end === false ) {
 470                         return array( false, false );
 471                 } else {
 472                         return array( $start, $end );
 473                 }
 474         }
 475
 476         /**
 477          * Convert a network specification in IPv6 CIDR notation to an
 478          * integer network and a number of bits
 479          *
 480          * @return array(string, int)
 481          */
 482         private static function parseCIDR6( $range ) {
 483                 # Explode into <expanded IP,range>
 484                 $parts = explode( '/', IP::sanitizeIP( $range ), 2 );
 485                 if ( count( $parts ) != 2 ) {
 486                         return array( false, false );
 487                 }
 488                 list( $network, $bits ) = $parts;
 489                 $network = self::IPv6ToRawHex( $network );
 490                 if ( $network !== false && is_numeric( $bits ) && $bits >= 0 && $bits <= 128 ) {
 491                         if ( $bits == 0 ) {
 492                                 $network = "0";
 493                         } else {
 494                                 # Native 32 bit functions WONT work here!!!
 495                                 # Convert to a padded binary number
 496                                 $network = wfBaseConvert( $network, 16, 2, 128 );
 497                                 # Truncate the last (128-$bits) bits and replace them with zeros
 498                                 $network = str_pad( substr( $network, 0, $bits ), 128, 0, STR_PAD_RIGHT );
 499                                 # Convert back to an integer
 500                                 $network = wfBaseConvert( $network, 2, 10 );
 501                         }
 502                 } else {
 503                         $network = false;
 504                         $bits = false;
 505                 }
 506                 return array( $network, (int)$bits );
 507         }
 508
 509         /**
 510          * Given a string range in a number of formats, return the
 511          * start and end of the range in hexadecimal. For IPv6.
 512          *
 513          * Formats are:
 514          *     2001:0db8:85a3::7344/96                                   CIDR
 515          *     2001:0db8:85a3::7344 - 2001:0db8:85a3::7344   Explicit range
 516          *     2001:0db8:85a3::7344/96                                   Single IP
 517          * @return array(string, string)
 518          */
 519         private static function parseRange6( $range ) {
 520                 # Expand any IPv6 IP
 521                 $range = IP::sanitizeIP( $range );
 522                 // CIDR notation...
 523                 if ( strpos( $range, '/' ) !== false ) {
 524                         list( $network, $bits ) = self::parseCIDR6( $range );
 525                         if ( $network === false ) {
 526                                 $start = $end = false;
 527                         } else {
 528                                 $start = wfBaseConvert( $network, 10, 16, 32, false );
 529                                 # Turn network to binary (again)
 530                                 $end = wfBaseConvert( $network, 10, 2, 128 );
 531                                 # Truncate the last (128-$bits) bits and replace them with ones
 532                                 $end = str_pad( substr( $end, 0, $bits ), 128, 1, STR_PAD_RIGHT );
 533                                 # Convert to hex
 534                                 $end = wfBaseConvert( $end, 2, 16, 32, false );
 535                                 # see toHex() comment
 536                                 $start = "v6-$start";
 537                                 $end = "v6-$end";
 538                         }
 539                 // Explicit range notation...
 540                 } elseif ( strpos( $range, '-' ) !== false ) {
 541                         list( $start, $end ) = array_map( 'trim', explode( '-', $range, 2 ) );
 542                         $start = self::toUnsigned6( $start );
 543                         $end = self::toUnsigned6( $end );
 544                         if ( $start > $end ) {
 545                                 $start = $end = false;
 546                         } else {
 547                                 $start = wfBaseConvert( $start, 10, 16, 32, false );
 548                                 $end = wfBaseConvert( $end, 10, 16, 32, false );
 549                         }
 550                         # see toHex() comment
 551                         $start = "v6-$start";
 552                         $end = "v6-$end";
 553                 } else {
 554                         # Single IP
 555                         $start = $end = self::toHex( $range );
 556                 }
 557                 if ( $start === false || $end === false ) {
 558                         return array( false, false );
 559                 } else {
 560                         return array( $start, $end );
 561                 }
 562         }
 563
 564         /**
 565          * Determine if a given IPv4/IPv6 address is in a given CIDR network
 566          *
 567          * @param $addr String: the address to check against the given range.
 568          * @param $range String: the range to check the given address against.
 569          * @return Boolean: whether or not the given address is in the given range.
 570          */
 571         public static function isInRange( $addr, $range ) {
 572                 $hexIP = self::toHex( $addr );
 573                 list( $start, $end ) = self::parseRange( $range );
 574                 return ( strcmp( $hexIP, $start ) >= 0 &&
 575                         strcmp( $hexIP, $end ) <= 0 );
 576         }
 577
 578         /**
 579          * Convert some unusual representations of IPv4 addresses to their
 580          * canonical dotted quad representation.
 581          *
 582          * This currently only checks a few IPV4-to-IPv6 related cases.  More
 583          * unusual representations may be added later.
 584          *
 585          * @param $addr String: something that might be an IP address
 586          * @return String: valid dotted quad IPv4 address or null
 587          */
 588         public static function canonicalize( $addr ) {
 589                 if ( self::isValid( $addr ) ) {
 590                         return $addr;
 591                 }
 592                 // Turn mapped addresses from ::ce:ffff:1.2.3.4 to 1.2.3.4
 593                 if ( strpos( $addr, ':' ) !== false && strpos( $addr, '.' ) !== false ) {
 594                         $addr = substr( $addr, strrpos( $addr, ':' ) + 1 );
 595                         if ( self::isIPv4( $addr ) ) {
 596                                 return $addr;
 597                         }
 598                 }
 599                 // IPv6 loopback address
 600                 $m = array();
 601                 if ( preg_match( '/^0*' . RE_IPV6_GAP . '1$/', $addr, $m ) ) {
 602                         return '127.0.0.1';
 603                 }
 604                 // IPv4-mapped and IPv4-compatible IPv6 addresses
 605                 if ( preg_match( '/^' . RE_IPV6_V4_PREFIX . '(' . RE_IP_ADD . ')$/i', $addr, $m ) ) {
 606                         return $m[1];
 607                 }
 608                 if ( preg_match( '/^' . RE_IPV6_V4_PREFIX . RE_IPV6_WORD .
 609                         ':' . RE_IPV6_WORD . '$/i', $addr, $m ) )
 610                 {
 611                         return long2ip( ( hexdec( $m[1] ) << 16 ) + hexdec( $m[2] ) );
 612                 }
 613
 614                 return null;  // give up
 615         }
 616 }