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 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
  33 // An IPv6 block is an IP address and a prefix (d1 to d128)
  34 define( 'RE_IPV6_WORD', '([0-9A-Fa-f]{1,4})' );
  35 define( 'RE_IPV6_PREFIX', '(12[0-8]|1[01][0-9]|[1-9]?\d)');
  36 // An IPv6 address is made up of 8 words. However, the "::" abbreviations can be used.
  37 define( 'RE_IPV6_ADD',
  38         '(' . // starts with "::" (includes the address "::")
  39                 '(::|:(:' . RE_IPV6_WORD . '){1,7})' .
  40         '|' . // ends with "::" (not including the address "::")
  41                 RE_IPV6_WORD . '(:' . RE_IPV6_WORD . '){0,6}::' .
  42         '|' . // has no "::"
  43                 RE_IPV6_WORD . '(:' . RE_IPV6_WORD . '){7}' .
  44         '|' . // contains one "::" in the middle ("^" check always fails if no "::" found)
  45                 RE_IPV6_WORD . '(:(?P<abbr>(?(abbr)|:))?' . RE_IPV6_WORD . '){1,6}(?(abbr)|^)' .
  46         ')'
  47 );
  48 define( 'RE_IPV6_BLOCK', RE_IPV6_ADD . '\/' . RE_IPV6_PREFIX );
  49 // For IPv6 canonicalization (NOT for strict validation; these are quite lax!)
  50 define( 'RE_IPV6_GAP', ':(?:0+:)*(?::(?:0+:)*)?' );
  51 define( 'RE_IPV6_V4_PREFIX', '0*' . RE_IPV6_GAP . '(?:ffff:)?' );
  52
  53 // This might be useful for regexps used elsewhere, matches any IPv6 or IPv6 address or network
  54 define( 'IP_ADDRESS_STRING',
  55         '(?:' .
  56                 RE_IP_ADD . '(\/' . RE_IP_PREFIX . '|)' . // IPv4
  57         '|' .
  58                 RE_IPV6_ADD . '(\/' . RE_IPV6_PREFIX . '|)' . // IPv6
  59         ')'
  60 );
  61
  62 /**
  63  * A collection of public static functions to play with IP address
  64  * and IP blocks.
  65  */
  66 class IP {
  67         /**
  68          * Determine if a string is as valid IP address or network (CIDR prefix).
  69          * SIIT IPv4-translated addresses are rejected.
  70          * Note: canonicalize() tries to convert translated addresses to IPv4.
  71          * @param string $ip possible IP address
  72          * @return bool
  73          */
  74         public static function isIPAddress( $ip ) {
  75                 return (bool)preg_match( '/^' . IP_ADDRESS_STRING . '$/', $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 string $ip possible IP address
  82          * @return bool
  83          */
  84         public static function isIPv6( $ip ) {
  85                 return (bool)preg_match( '/^' . RE_IPV6_ADD . '(\/' . RE_IPV6_PREFIX . '|)$/', $ip );
  86         }
  87
  88         /**
  89          * Given a string, determine if it as valid IP in IPv4 only.
  90          * Note: Unlike isValid(), this looks for networks too.
  91          * @param string $ip possible IP address
  92          * @return bool
  93          */
  94         public static function isIPv4( $ip ) {
  95                 return (bool)preg_match( '/^' . RE_IP_ADD . '(\/' . RE_IP_PREFIX . '|)$/', $ip );
  96         }
  97
  98         /**
  99          * Validate an IP address. Ranges are NOT considered valid.
 100          * SIIT IPv4-translated addresses are rejected.
 101          * Note: canonicalize() tries to convert translated addresses to IPv4.
 102          * @param string $ip
 103          * @return boolean True if it is valid.
 104          */
 105         public static function isValid( $ip ) {
 106                 return ( preg_match( '/^' . RE_IP_ADD . '$/', $ip )
 107                         || preg_match( '/^' . RE_IPV6_ADD . '$/', $ip ) );
 108         }
 109
 110         /**
 111          * Validate an IP Block (valid address WITH a valid prefix).
 112          * SIIT IPv4-translated addresses are rejected.
 113          * Note: canonicalize() tries to convert translated addresses to IPv4.
 114          * @param string $ipblock
 115          * @return boolean True if it is valid.
 116          */
 117         public static function isValidBlock( $ipblock ) {
 118                 return ( preg_match( '/^' . RE_IPV6_BLOCK . '$/', $ipblock )
 119                         || preg_match( '/^' . RE_IPV4_BLOCK . '$/', $ipblock ) );
 120         }
 121
 122         /**
 123          * Given an IP address in dotted-quad notation, returns an IPv6 octet.
 124          * See http://www.answers.com/topic/ipv4-compatible-address
 125          * IPs with the first 92 bits as zeros are reserved from IPv6
 126          * @param string $ip quad-dotted IP address.
 127          * @return string
 128          */
 129         public static function IPv4toIPv6( $ip ) {
 130                 if ( !$ip ) {
 131                         return null;
 132                 }
 133                 // Convert only if needed
 134                 if ( self::isIPv6( $ip ) ) {
 135                         return $ip;
 136                 }
 137                 // IPv4 address with CIDR
 138                 if ( strpos( $ip, '/' ) !== false ) {
 139                         $parts = explode( '/', $ip, 2 );
 140                         if ( count( $parts ) != 2 ) {
 141                                 return false;
 142                         }
 143                         list( $network, $bits ) = $parts;
 144                         $network = self::toUnsigned( $network );
 145                         if ( $network !== false && is_numeric( $bits ) && $bits >= 0 && $bits <= 32 ) {
 146                                 $bits += 96;
 147                                 return self::toOctet( $network ) . "/$bits";
 148                         } else {
 149                                 return false;
 150                         }
 151                 }
 152                 return self::toOctet( self::toUnsigned( $ip ) );
 153         }
 154
 155         /**
 156          * Convert an IP into a nice standard form.
 157          * IPv6 addresses in octet notation are expanded to 8 words.
 158          * IPv4 addresses are just trimmed.
 159          * @param string $ip IP address in quad or octet form (CIDR or not).
 160          * @return string
 161          */
 162         public static function sanitizeIP( $ip ) {
 163                 $ip = trim( $ip );
 164                 if ( $ip === '' ) {
 165                         return null;
 166                 }
 167                 if ( self::isIPv4( $ip ) || !self::isIPv6( $ip ) ) {
 168                         return $ip; // nothing else to do for IPv4 addresses or invalid ones
 169                 }
 170                 // Remove any whitespaces, convert to upper case
 171                 $ip = strtoupper( $ip );
 172                 // Expand zero abbreviations
 173                 $abbrevPos = strpos( $ip, '::' );
 174                 if ( $abbrevPos !== false ) {
 175                         // We know this is valid IPv6. Find the last index of the
 176                         // address before any CIDR number (e.g. "a:b:c::/24").
 177                         $CIDRStart = strpos( $ip, "/" );
 178                         $addressEnd = ( $CIDRStart !== false )
 179                                 ? $CIDRStart - 1
 180                                 : strlen( $ip ) - 1;
 181                         // If the '::' is at the beginning...
 182                         if( $abbrevPos == 0 ) {
 183                                 $repeat = '0:';
 184                                 $extra = ( $ip == '::' ) ? '0' : ''; // for the address '::'
 185                                 $pad = 9; // 7+2 (due to '::')
 186                         // If the '::' is at the end...
 187                         } elseif( $abbrevPos == ( $addressEnd - 1 ) ) {
 188                                 $repeat = ':0';
 189                                 $extra = '';
 190                                 $pad = 9; // 7+2 (due to '::')
 191                         // If the '::' is in the middle...
 192                         } else {
 193                                 $repeat = ':0';
 194                                 $extra = ':';
 195                                 $pad = 8; // 6+2 (due to '::')
 196                         }
 197                         $ip = str_replace( '::',
 198                                 str_repeat( $repeat, $pad - substr_count( $ip, ':' ) ) . $extra,
 199                                 $ip
 200                         );
 201                 }
 202                 // Remove leading zereos from each bloc as needed
 203                 $ip = preg_replace( '/(^|:)0+' . RE_IPV6_WORD . '/', '$1$2', $ip );
 204                 return $ip;
 205         }
 206
 207         /**
 208          * Given an unsigned integer, returns an IPv6 address in octet notation
 209          * @param string $ip_int IP address.
 210          * @return string
 211          */
 212         public static function toOctet( $ip_int ) {
 213                 return self::hexToOctet( wfBaseConvert( $ip_int, 10, 16, 32, false ) );
 214         }
 215
 216         /**
 217          * Convert an IPv4 or IPv6 hexadecimal representation back to readable format
 218          * @param string $hex number, with "v6-" prefix if it is IPv6
 219          * @return string quad-dotted (IPv4) or octet notation (IPv6)
 220          */
 221         public static function formatHex( $hex ) {
 222                 if ( substr( $hex, 0, 3 ) == 'v6-' ) { // IPv6
 223                         return self::hexToOctet( substr( $hex, 3 ) );
 224                 } else { // IPv4
 225                         return self::hexToQuad( $hex );
 226                 }
 227         }
 228
 229         /**
 230          * Converts a hexadecimal number to an IPv6 address in octet notation
 231          * @param string $ip_hex pure hex (no v6- prefix)
 232          * @return string (of format a:b:c:d:e:f:g:h)
 233          */
 234         public static function hexToOctet( $ip_hex ) {
 235                 // Pad hex to 32 chars (128 bits)
 236                 $ip_hex = str_pad( strtoupper( $ip_hex ), 32, '0', STR_PAD_LEFT );
 237                 // Separate into 8 words
 238                 $ip_oct = substr( $ip_hex, 0, 4 );
 239                 for ( $n = 1; $n < 8; $n++ ) {
 240                         $ip_oct .= ':' . substr( $ip_hex, 4 * $n, 4 );
 241                 }
 242                 // NO leading zeroes
 243                 $ip_oct = preg_replace( '/(^|:)0+' . RE_IPV6_WORD . '/', '$1$2', $ip_oct );
 244                 return $ip_oct;
 245         }
 246
 247         /**
 248          * Converts a hexadecimal number to an IPv4 address in quad-dotted notation
 249          * @param string $ip_hex pure hex
 250          * @return string (of format a.b.c.d)
 251          */
 252         public static function hexToQuad( $ip_hex ) {
 253                 // Pad hex to 8 chars (32 bits)
 254                 $ip_hex = str_pad( strtoupper( $ip_hex ), 8, '0', STR_PAD_LEFT );
 255                 // Separate into four quads
 256                 $s = '';
 257                 for ( $i = 0; $i < 4; $i++ ) {
 258                         if ( $s !== '' ) {
 259                                 $s .= '.';
 260                         }
 261                         $s .= base_convert( substr( $ip_hex, $i * 2, 2 ), 16, 10 );
 262                 }
 263                 return $s;
 264         }
 265
 266         /**
 267          * Determine if an IP address really is an IP address, and if it is public,
 268          * i.e. not RFC 1918 or similar
 269          * Comes from ProxyTools.php
 270          * @param string $ip
 271          * @return bool
 272          */
 273         public static function isPublic( $ip ) {
 274                 if ( self::isIPv6( $ip ) ) {
 275                         return self::isPublic6( $ip );
 276                 }
 277                 $n = self::toUnsigned( $ip );
 278                 if ( !$n ) {
 279                         return false;
 280                 }
 281
 282                 // ip2long accepts incomplete addresses, as well as some addresses
 283                 // followed by garbage characters. Check that it's really valid.
 284                 if( $ip != long2ip( $n ) ) {
 285                         return false;
 286                 }
 287
 288                 static $privateRanges = false;
 289                 if ( !$privateRanges ) {
 290                         $privateRanges = array(
 291                                 array( '10.0.0.0',    '10.255.255.255' ),   # RFC 1918 (private)
 292                                 array( '172.16.0.0',  '172.31.255.255' ),   #     "
 293                                 array( '192.168.0.0', '192.168.255.255' ),  #     "
 294                                 array( '0.0.0.0',     '0.255.255.255' ),    # this network
 295                                 array( '127.0.0.0',   '127.255.255.255' ),  # loopback
 296                         );
 297                 }
 298
 299                 foreach ( $privateRanges as $r ) {
 300                         $start = self::toUnsigned( $r[0] );
 301                         $end = self::toUnsigned( $r[1] );
 302                         if ( $n >= $start && $n <= $end ) {
 303                                 return false;
 304                         }
 305                 }
 306                 return true;
 307         }
 308
 309         /**
 310          * Determine if an IPv6 address really is an IP address, and if it is public,
 311          * i.e. not RFC 4193 or similar
 312          * @param string $ip
 313          * @return bool
 314          */
 315         private static function isPublic6( $ip ) {
 316                 static $privateRanges = false;
 317                 if ( !$privateRanges ) {
 318                         $privateRanges = array(
 319                                 array( 'fc::', 'fdff:ffff:ffff:ffff:ffff:ffff:ffff:ffff' ), # RFC 4193 (local)
 320                                 array( '0:0:0:0:0:0:0:1', '0:0:0:0:0:0:0:1' ), # loopback
 321                         );
 322                 }
 323                 $n = self::toHex( $ip );
 324                 foreach ( $privateRanges as $r ) {
 325                         $start = self::toHex( $r[0] );
 326                         $end = self::toHex( $r[1] );
 327                         if ( $n >= $start && $n <= $end ) {
 328                                 return false;
 329                         }
 330                 }
 331                 return true;
 332         }
 333
 334         /**
 335          * Return a zero-padded upper case hexadecimal representation of an IP address.
 336          *
 337          * Hexadecimal addresses are used because they can easily be extended to
 338          * IPv6 support. To separate the ranges, the return value from this
 339          * function for an IPv6 address will be prefixed with "v6-", a non-
 340          * hexadecimal string which sorts after the IPv4 addresses.
 341          *
 342          * @param string $ip Quad dotted/octet IP address.
 343          * @return string
 344          */
 345         public static function toHex( $ip ) {
 346                 if ( self::isIPv6( $ip ) ) {
 347                         $n = 'v6-' . self::IPv6ToRawHex( $ip );
 348                 } else {
 349                         $n = self::toUnsigned( $ip );
 350                         if ( $n !== false ) {
 351                                 $n = wfBaseConvert( $n, 10, 16, 8, false );
 352                         }
 353                 }
 354                 return $n;
 355         }
 356
 357         /**
 358          * Given an IPv6 address in octet notation, returns a pure hex string.
 359          * @param string $ip octet ipv6 IP address.
 360          * @return string pure hex (uppercase)
 361          */
 362         private static function IPv6ToRawHex( $ip ) {
 363                 $ip = self::sanitizeIP( $ip );
 364                 if ( !$ip ) {
 365                         return null;
 366                 }
 367                 $r_ip = '';
 368                 foreach ( explode( ':', $ip ) as $v ) {
 369                         $r_ip .= str_pad( $v, 4, 0, STR_PAD_LEFT );
 370                 }
 371                 return $r_ip;
 372         }
 373
 374         /**
 375          * Given an IP address in dotted-quad/octet notation, returns an unsigned integer.
 376          * Like ip2long() except that it actually works and has a consistent error return value.
 377          * Comes from ProxyTools.php
 378          * @param string $ip Quad dotted IP address.
 379          * @return mixed (string/int/false)
 380          */
 381         public static function toUnsigned( $ip ) {
 382                 if ( self::isIPv6( $ip ) ) {
 383                         $n = wfBaseConvert( self::IPv6ToRawHex( $ip ), 16, 10 );
 384                 } else {
 385                         $n = ip2long( $ip );
 386                         if ( $n < 0 ) {
 387                                 $n += pow( 2, 32 );
 388                         }
 389                 }
 390                 return $n;
 391         }
 392
 393         private static function toUnsigned6( $ip ) {
 394                 return wfBaseConvert( self::IPv6ToRawHex( $ip ), 16, 10 );
 395         }
 396
 397         /**
 398          * Convert a network specification in CIDR notation
 399          * to an integer network and a number of bits
 400          * @param string $range (CIDR IP)
 401          * @return array(int, int)
 402          */
 403         public static function parseCIDR( $range ) {
 404                 $parts = explode( '/', $range, 2 );
 405                 if ( count( $parts ) != 2 ) {
 406                         return array( false, false );
 407                 }
 408                 list( $network, $bits ) = $parts;
 409                 $network = ip2long( $network );
 410                 if ( $network !== false && is_numeric( $bits ) && $bits >= 0 && $bits <= 32 ) {
 411                         if ( $bits == 0 ) {
 412                                 $network = 0;
 413                         } else {
 414                                 $network &= ~( ( 1 << ( 32 - $bits ) ) - 1);
 415                         }
 416                         # Convert to unsigned
 417                         if ( $network < 0 ) {
 418                                 $network += pow( 2, 32 );
 419                         }
 420                 } else {
 421                         $network = false;
 422                         $bits = false;
 423                 }
 424                 return array( $network, $bits );
 425         }
 426
 427         /**
 428          * Given a string range in a number of formats, return the start and end of
 429          * the range in hexadecimal.
 430          *
 431          * Formats are:
 432          *     1.2.3.4/24          CIDR
 433          *     1.2.3.4 - 1.2.3.5   Explicit range
 434          *     1.2.3.4             Single IP
 435          *
 436          *     2001:0db8:85a3::7344/96                                   CIDR
 437          *     2001:0db8:85a3::7344 - 2001:0db8:85a3::7344   Explicit range
 438          *     2001:0db8:85a3::7344                                      Single IP
 439          * @param string $range IP range
 440          * @return array(string, int)
 441          */
 442         public static function parseRange( $range ) {
 443                 // Use IPv6 functions if needed
 444                 if ( self::isIPv6( $range ) ) {
 445                         return self::parseRange6( $range );
 446                 }
 447                 if ( strpos( $range, '/' ) !== false ) {
 448                         # CIDR
 449                         list( $network, $bits ) = self::parseCIDR( $range );
 450                         if ( $network === false ) {
 451                                 $start = $end = false;
 452                         } else {
 453                                 $start = sprintf( '%08X', $network );
 454                                 $end = sprintf( '%08X', $network + pow( 2, ( 32 - $bits ) ) - 1 );
 455                         }
 456                 } elseif ( strpos( $range, '-' ) !== false ) {
 457                         # Explicit range
 458                         list( $start, $end ) = array_map( 'trim', explode( '-', $range, 2 ) );
 459                         if( self::isIPAddress( $start ) && self::isIPAddress( $end ) ) {
 460                                 $start = self::toUnsigned( $start );
 461                                 $end = self::toUnsigned( $end );
 462                                 if ( $start > $end ) {
 463                                         $start = $end = false;
 464                                 } else {
 465                                         $start = sprintf( '%08X', $start );
 466                                         $end = sprintf( '%08X', $end );
 467                                 }
 468                         } else {
 469                                 $start = $end = false;
 470                         }
 471                 } else {
 472                         # Single IP
 473                         $start = $end = self::toHex( $range );
 474                 }
 475                 if ( $start === false || $end === false ) {
 476                         return array( false, false );
 477                 } else {
 478                         return array( $start, $end );
 479                 }
 480         }
 481
 482         /**
 483          * Convert a network specification in IPv6 CIDR notation to an
 484          * integer network and a number of bits
 485          * @return array(string, int)
 486          */
 487         private static function parseCIDR6( $range ) {
 488                 # Explode into <expanded IP,range>
 489                 $parts = explode( '/', IP::sanitizeIP( $range ), 2 );
 490                 if ( count( $parts ) != 2 ) {
 491                         return array( false, false );
 492                 }
 493                 list( $network, $bits ) = $parts;
 494                 $network = self::IPv6ToRawHex( $network );
 495                 if ( $network !== false && is_numeric( $bits ) && $bits >= 0 && $bits <= 128 ) {
 496                         if ( $bits == 0 ) {
 497                                 $network = "0";
 498                         } else {
 499                                 # Native 32 bit functions WONT work here!!!
 500                                 # Convert to a padded binary number
 501                                 $network = wfBaseConvert( $network, 16, 2, 128 );
 502                                 # Truncate the last (128-$bits) bits and replace them with zeros
 503                                 $network = str_pad( substr( $network, 0, $bits ), 128, 0, STR_PAD_RIGHT );
 504                                 # Convert back to an integer
 505                                 $network = wfBaseConvert( $network, 2, 10 );
 506                         }
 507                 } else {
 508                         $network = false;
 509                         $bits = false;
 510                 }
 511                 return array( $network, (int)$bits );
 512         }
 513
 514         /**
 515          * Given a string range in a number of formats, return the
 516          * start and end of the range in hexadecimal. For IPv6.
 517          *
 518          * Formats are:
 519          *     2001:0db8:85a3::7344/96                                   CIDR
 520          *     2001:0db8:85a3::7344 - 2001:0db8:85a3::7344   Explicit range
 521          *     2001:0db8:85a3::7344/96                                   Single IP
 522          * @return array(string, int)
 523          */
 524         private static function parseRange6( $range ) {
 525                 # Expand any IPv6 IP
 526                 $range = IP::sanitizeIP( $range );
 527                 // CIDR notation...
 528                 if ( strpos( $range, '/' ) !== false ) {
 529                         list( $network, $bits ) = self::parseCIDR6( $range );
 530                         if ( $network === false ) {
 531                                 $start = $end = false;
 532                         } else {
 533                                 $start = wfBaseConvert( $network, 10, 16, 32, false );
 534                                 # Turn network to binary (again)
 535                                 $end = wfBaseConvert( $network, 10, 2, 128 );
 536                                 # Truncate the last (128-$bits) bits and replace them with ones
 537                                 $end = str_pad( substr( $end, 0, $bits ), 128, 1, STR_PAD_RIGHT );
 538                                 # Convert to hex
 539                                 $end = wfBaseConvert( $end, 2, 16, 32, false );
 540                                 # see toHex() comment
 541                                 $start = "v6-$start";
 542                                 $end = "v6-$end";
 543                         }
 544                 // Explicit range notation...
 545                 } elseif ( strpos( $range, '-' ) !== false ) {
 546                         list( $start, $end ) = array_map( 'trim', explode( '-', $range, 2 ) );
 547                         $start = self::toUnsigned6( $start );
 548                         $end = self::toUnsigned6( $end );
 549                         if ( $start > $end ) {
 550                                 $start = $end = false;
 551                         } else {
 552                                 $start = wfBaseConvert( $start, 10, 16, 32, false );
 553                                 $end = wfBaseConvert( $end, 10, 16, 32, false );
 554                         }
 555                         # see toHex() comment
 556                         $start = "v6-$start";
 557                         $end = "v6-$end";
 558                 } else {
 559                         # Single IP
 560                         $start = $end = self::toHex( $range );
 561                 }
 562                 if ( $start === false || $end === false ) {
 563                         return array( false, false );
 564                 } else {
 565                         return array( $start, $end );
 566                 }
 567         }
 568
 569         /**
 570          * Determine if a given IPv4/IPv6 address is in a given CIDR network
 571          * @param $addr The address to check against the given range.
 572          * @param $range The range to check the given address against.
 573          * @return bool Whether or not the given address is in the given range.
 574          */
 575         public static function isInRange( $addr, $range ) {
 576                 $hexIP = self::toHex( $addr );
 577                 list( $start, $end ) = self::parseRange( $range );
 578                 return ( strcmp( $hexIP, $start ) >= 0 &&
 579                         strcmp( $hexIP, $end ) <= 0 );
 580         }
 581
 582         /**
 583          * Convert some unusual representations of IPv4 addresses to their
 584          * canonical dotted quad representation.
 585          *
 586          * This currently only checks a few IPV4-to-IPv6 related cases.  More
 587          * unusual representations may be added later.
 588          *
 589          * @param $addr something that might be an IP address
 590          * @return valid dotted quad IPv4 address or null
 591          */
 592         public static function canonicalize( $addr ) {
 593                 if ( self::isValid( $addr ) ) {
 594                         return $addr;
 595                 }
 596
 597                 // Turn mapped addresses from ::ce:ffff:1.2.3.4 to 1.2.3.4
 598                 if ( strpos( $addr, ':' ) !== false && strpos( $addr, '.' ) !== false ) {
 599                         $addr = substr( $addr, strrpos( $addr, ':' ) + 1 );
 600                         if( self::isIPv4( $addr ) ) {
 601                                 return $addr;
 602                         }
 603                 }
 604
 605                 // IPv6 loopback address
 606                 $m = array();
 607                 if ( preg_match( '/^0*' . RE_IPV6_GAP . '1$/', $addr, $m ) ) {
 608                         return '127.0.0.1';
 609                 }
 610
 611                 // IPv4-mapped and IPv4-compatible IPv6 addresses
 612                 if ( preg_match( '/^' . RE_IPV6_V4_PREFIX . '(' . RE_IP_ADD . ')$/i', $addr, $m ) ) {
 613                         return $m[1];
 614                 }
 615                 if ( preg_match( '/^' . RE_IPV6_V4_PREFIX . RE_IPV6_WORD . ':' . RE_IPV6_WORD . '$/i', $addr, $m ) ) {
 616                         return long2ip( ( hexdec( $m[1] ) << 16 ) + hexdec( $m[2] ) );
 617                 }
 618
 619                 return null;  // give up
 620         }
 621 }