includes/IP.php

   1 <?php
   2 /**
   3  * Functions and constants to play with IP addresses and ranges
   4  *
   5  * @file
   6  * @author Ashar Voultoiz <hashar at free dot fr>
   7  * @license GPL v2 or later
   8  */
   9
  10 // Some regex definition to "play" with IP address and IP address blocks
  11
  12 // An IP is made of 4 bytes from x00 to xFF which is d0 to d255
  13 define( 'RE_IP_BYTE', '(25[0-5]|2[0-4][0-9]|1[0-9][0-9]|0?[0-9]?[0-9])' );
  14 define( 'RE_IP_ADD' , RE_IP_BYTE . '\.' . RE_IP_BYTE . '\.' . RE_IP_BYTE . '\.' . RE_IP_BYTE );
  15 // An IPv4 block is an IP address and a prefix (d1 to d32)
  16 define( 'RE_IP_PREFIX', '(3[0-2]|[12]?\d)' );
  17 define( 'RE_IP_BLOCK', RE_IP_ADD . '\/' . RE_IP_PREFIX );
  18 // For IPv6 canonicalization (NOT for strict validation; these are quite lax!)
  19 define( 'RE_IPV6_WORD', '([0-9A-Fa-f]{1,4})' );
  20 define( 'RE_IPV6_GAP', ':(?:0+:)*(?::(?:0+:)*)?' );
  21 define( 'RE_IPV6_V4_PREFIX', '0*' . RE_IPV6_GAP . '(?:ffff:)?' );
  22 // An IPv6 block is an IP address and a prefix (d1 to d128)
  23 define( 'RE_IPV6_PREFIX', '(12[0-8]|1[01][0-9]|[1-9]?\d)');
  24 // An IPv6 IP is made up of 8 octets. However abbreviations like "::" can be used.
  25 // This is lax! Number of octets/double colons validation not done.
  26 define( 'RE_IPV6_ADD',
  27         '(' .
  28                 ':(:' . RE_IPV6_WORD . '){1,7}' . // IPs that start with ":"
  29         '|' .
  30                 RE_IPV6_WORD . '(:{1,2}' . RE_IPV6_WORD . '|::$){1,7}' . // IPs that don't start with ":"
  31         ')'
  32 );
  33 define( 'RE_IPV6_BLOCK', RE_IPV6_ADD . '\/' . RE_IPV6_PREFIX );
  34 // This might be useful for regexps used elsewhere, matches any IPv6 or IPv6 address or network
  35 define( 'IP_ADDRESS_STRING',
  36         '(?:' .
  37                 RE_IP_ADD . '(\/' . RE_IP_PREFIX . '|)' . // IPv4
  38         '|' .
  39                 RE_IPV6_ADD . '(\/' . RE_IPV6_PREFIX . '|)' . // IPv6
  40         ')'
  41 );
  42
  43 /**
  44  * A collection of public static functions to play with IP address
  45  * and IP blocks.
  46  */
  47 class IP {
  48         /**
  49          * Given a string, determine if it as valid IP
  50          * Unlike isValid(), this looks for networks too
  51          * @param $ip IP address.
  52          * @return string
  53          */
  54         public static function isIPAddress( $ip ) {
  55                 if ( !$ip ) {
  56                         return false;
  57                 }
  58                 if ( is_array( $ip ) ) {
  59                   throw new MWException( 'invalid value passed to ' . __METHOD__ );
  60                 }
  61                 // IPv6 IPs with two "::" strings are ambiguous and thus invalid
  62                 return preg_match( '/^' . IP_ADDRESS_STRING . '$/', $ip ) && ( substr_count( $ip, '::' ) < 2 );
  63         }
  64
  65         public static function isIPv6( $ip ) {
  66                 if ( !$ip ) {
  67                         return false;
  68                 }
  69                 if( is_array( $ip ) ) {
  70                         throw new MWException( 'invalid value passed to ' . __METHOD__ );
  71                 }
  72                 $doubleColons = substr_count( $ip, '::' );
  73                 // IPv6 IPs with two "::" strings are ambiguous and thus invalid
  74                 return preg_match( '/^' . RE_IPV6_ADD . '(\/' . RE_IPV6_PREFIX . '|)$/', $ip )
  75                         && ( $doubleColons == 1 || substr_count( $ip, ':' ) == 7 );
  76         }
  77
  78         public static function isIPv4( $ip ) {
  79                 if ( !$ip ) {
  80                         return false;
  81                 }
  82                 return preg_match( '/^' . RE_IP_ADD . '(\/' . RE_IP_PREFIX . '|)$/', $ip);
  83         }
  84
  85         /**
  86          * Given an IP address in dotted-quad notation, returns an IPv6 octet.
  87          * See http://www.answers.com/topic/ipv4-compatible-address
  88          * IPs with the first 92 bits as zeros are reserved from IPv6
  89          * @param $ip quad-dotted IP address.
  90          * @return string
  91          */
  92         public static function IPv4toIPv6( $ip ) {
  93                 if ( !$ip ) {
  94                         return null;
  95                 }
  96                 // Convert only if needed
  97                 if ( self::isIPv6( $ip ) ) {
  98                         return $ip;
  99                 }
 100                 // IPv4 CIDRs
 101                 if ( strpos( $ip, '/' ) !== false ) {
 102                         $parts = explode( '/', $ip, 2 );
 103                         if ( count( $parts ) != 2 ) {
 104                                 return false;
 105                         }
 106                         $network = self::toUnsigned( $parts[0] );
 107                         if ( $network !== false && is_numeric( $parts[1] ) && $parts[1] >= 0 && $parts[1] <= 32 ) {
 108                                 $bits = $parts[1] + 96;
 109                                 return self::toOctet( $network ) . "/$bits";
 110                         } else {
 111                                 return false;
 112                         }
 113                 }
 114                 return self::toOctet( self::toUnsigned( $ip ) );
 115         }
 116
 117         /**
 118          * Given an IPv6 address in octet notation, returns an unsigned integer.
 119          * @param $ip octet ipv6 IP address.
 120          * @return string
 121          */
 122         public static function toUnsigned6( $ip ) {
 123                 if ( !$ip ) {
 124                         return null;
 125                 }
 126                 $ip = explode( ':', self::sanitizeIP( $ip ) );
 127                 $r_ip = '';
 128                 foreach ( $ip as $v ) {
 129                         $r_ip .= str_pad( $v, 4, 0, STR_PAD_LEFT );
 130                 }
 131                 $r_ip = wfBaseConvert( $r_ip, 16, 10 );
 132                 return $r_ip;
 133         }
 134
 135         /**
 136          * Given an IPv6 address in octet notation, returns the expanded octet.
 137          * IPv4 IPs will be trimmed, thats it...
 138          * @param $ip octet ipv6 IP address.
 139          * @return string
 140          */
 141         public static function sanitizeIP( $ip ) {
 142                 $ip = trim( $ip );
 143                 if ( $ip === '' ) {
 144                         return null;
 145                 }
 146                 // Trim and return IPv4 addresses
 147                 if ( self::isIPv4( $ip ) ) {
 148                         return $ip;
 149                 }
 150                 // Only IPv6 addresses can be expanded
 151                 if ( !self::isIPv6( $ip ) ) {
 152                         return $ip;
 153                 }
 154                 // Remove any whitespaces, convert to upper case
 155                 $ip = strtoupper( $ip );
 156                 // Expand zero abbreviations
 157                 $abbrevPos = strpos( $ip, '::' );
 158                 if ( $abbrevPos !== false ) {
 159                         // If the '::' is at the beginning...
 160                         if( $abbrevPos == 0 ) {
 161                                 $repeat = '0:';
 162                                 $extra = '';
 163                                 $pad = 9; // 7+2 (due to '::')
 164                         // If the '::' is at the end...
 165                         } elseif( $abbrevPos == ( strlen( $ip ) - 2 ) ) {
 166                                 $repeat = ':0';
 167                                 $extra = '';
 168                                 $pad = 9; // 7+2 (due to '::')
 169                         // If the '::' is at the end...
 170                         } else {
 171                                 $repeat = ':0';
 172                                 $extra = ':';
 173                                 $pad = 8; // 6+2 (due to '::')
 174                         }
 175                         $ip = str_replace( '::', str_repeat( $repeat, $pad - substr_count( $ip, ':' ) ) . $extra, $ip );
 176                 }
 177                 // Remove leading zereos from each bloc as needed
 178                 $ip = preg_replace( '/(^|:)0+' . RE_IPV6_WORD . '/', '$1$2', $ip );
 179                 return $ip;
 180         }
 181
 182         /**
 183          * Given an unsigned integer, returns an IPv6 address in octet notation
 184          * @param $ip_int integer IP address.
 185          * @return string
 186          */
 187         public static function toOctet( $ip_int ) {
 188                 // Convert to padded uppercase hex
 189                 $ip_hex = wfBaseConvert( $ip_int, 10, 16, 32, false );
 190                 // Separate into 8 octets
 191                 $ip_oct = substr( $ip_hex, 0, 4 );
 192                 for ( $n = 1; $n < 8; $n++ ) {
 193                         $ip_oct .= ':' . substr( $ip_hex, 4 * $n, 4 );
 194                 }
 195                 // NO leading zeroes
 196                 $ip_oct = preg_replace( '/(^|:)0+' . RE_IPV6_WORD . '/', '$1$2', $ip_oct );
 197                 return $ip_oct;
 198         }
 199
 200         /**
 201          * Convert an IPv4 or IPv6 hexadecimal representation back to readable format
 202          */
 203         public static function formatHex( $hex ) {
 204                 if ( substr( $hex, 0, 3 ) == 'v6-' ) {
 205                         return self::hexToOctet( $hex );
 206                 } else {
 207                         return self::hexToQuad( $hex );
 208                 }
 209         }
 210
 211         /**
 212          * Given a hexadecimal number, returns to an IPv6 address in octet notation
 213          * @param $ip_hex string hex IP
 214          * @return string
 215          */
 216         public static function hextoOctet( $ip_hex ) {
 217                 // Convert to padded uppercase hex
 218                 $ip_hex = str_pad( strtoupper( $ip_hex ), 32, '0' );
 219                 // Separate into 8 octets
 220                 $ip_oct = substr( $ip_hex, 0, 4 );
 221                 for ( $n = 1; $n < 8; $n++ ) {
 222                         $ip_oct .= ':' . substr( $ip_hex, 4 * $n, 4 );
 223                 }
 224                 // NO leading zeroes
 225                 $ip_oct = preg_replace( '/(^|:)0+' . RE_IPV6_WORD . '/', '$1$2', $ip_oct );
 226                 return $ip_oct;
 227         }
 228
 229         /**
 230          * Converts a hexadecimal number to an IPv4 address in octet notation
 231          * @param $ip string Hex IP
 232          * @return string
 233          */
 234         public static function hexToQuad( $ip ) {
 235                 // Converts a hexadecimal IP to nnn.nnn.nnn.nnn format
 236                 $s = '';
 237                 for ( $i = 0; $i < 4; $i++ ) {
 238                         if ( $s !== '' ) {
 239                                 $s .= '.';
 240                         }
 241                         $s .= base_convert( substr( $ip, $i * 2, 2 ), 16, 10 );
 242                 }
 243                 return $s;
 244         }
 245
 246         /**
 247          * Convert a network specification in IPv6 CIDR notation to an integer network and a number of bits
 248          * @return array(string, int)
 249          */
 250         public static function parseCIDR6( $range ) {
 251                 # Expand any IPv6 IP
 252                 $parts = explode( '/', IP::sanitizeIP( $range ), 2 );
 253                 if ( count( $parts ) != 2 ) {
 254                         return array( false, false );
 255                 }
 256                 $network = self::toUnsigned6( $parts[0] );
 257                 if ( $network !== false && is_numeric( $parts[1] ) && $parts[1] >= 0 && $parts[1] <= 128 ) {
 258                         $bits = $parts[1];
 259                         if ( $bits == 0 ) {
 260                                 $network = 0;
 261                         } else {
 262                         # Native 32 bit functions WONT work here!!!
 263                         # Convert to a padded binary number
 264                                 $network = wfBaseConvert( $network, 10, 2, 128 );
 265                         # Truncate the last (128-$bits) bits and replace them with zeros
 266                                 $network = str_pad( substr( $network, 0, $bits ), 128, 0, STR_PAD_RIGHT );
 267                         # Convert back to an integer
 268                                 $network = wfBaseConvert( $network, 2, 10 );
 269                         }
 270                 } else {
 271                         $network = false;
 272                         $bits = false;
 273                 }
 274                 return array( $network, $bits );
 275         }
 276
 277         /**
 278          * Given a string range in a number of formats, return the start and end of
 279          * the range in hexadecimal. For IPv6.
 280          *
 281          * Formats are:
 282          *     2001:0db8:85a3::7344/96                                   CIDR
 283          *     2001:0db8:85a3::7344 - 2001:0db8:85a3::7344   Explicit range
 284          *     2001:0db8:85a3::7344/96                                   Single IP
 285          * @return array(string, int)
 286          */
 287         public static function parseRange6( $range ) {
 288                 # Expand any IPv6 IP
 289                 $range = IP::sanitizeIP( $range );
 290                 if ( strpos( $range, '/' ) !== false ) {
 291                         # CIDR
 292                         list( $network, $bits ) = self::parseCIDR6( $range );
 293                         if ( $network === false ) {
 294                                 $start = $end = false;
 295                         } else {
 296                                 $start = wfBaseConvert( $network, 10, 16, 32, false );
 297                                 # Turn network to binary (again)
 298                                 $end = wfBaseConvert( $network, 10, 2, 128 );
 299                                 # Truncate the last (128-$bits) bits and replace them with ones
 300                                 $end = str_pad( substr( $end, 0, $bits ), 128, 1, STR_PAD_RIGHT );
 301                                 # Convert to hex
 302                                 $end = wfBaseConvert( $end, 2, 16, 32, false );
 303                                 # see toHex() comment
 304                                 $start = "v6-$start";
 305                                 $end = "v6-$end";
 306                         }
 307                 } elseif ( strpos( $range, '-' ) !== false ) {
 308                         # Explicit range
 309                         list( $start, $end ) = array_map( 'trim', explode( '-', $range, 2 ) );
 310                         $start = self::toUnsigned6( $start );
 311                         $end = self::toUnsigned6( $end );
 312                         if ( $start > $end ) {
 313                                 $start = $end = false;
 314                         } else {
 315                                 $start = wfBaseConvert( $start, 10, 16, 32, false );
 316                                 $end = wfBaseConvert( $end, 10, 16, 32, false );
 317                         }
 318                         # see toHex() comment
 319                         $start = "v6-$start";
 320                         $end = "v6-$end";
 321                 } else {
 322                         # Single IP
 323                         $start = $end = self::toHex( $range );
 324                 }
 325                 if ( $start === false || $end === false ) {
 326                         return array( false, false );
 327                 } else {
 328                         return array( $start, $end );
 329                 }
 330         }
 331
 332         /**
 333          * Validate an IP address.
 334          * @return boolean True if it is valid.
 335          */
 336         public static function isValid( $ip ) {
 337                 return ( preg_match( '/^' . RE_IP_ADD . '$/', $ip ) || preg_match( '/^' . RE_IPV6_ADD . '$/', $ip ) );
 338         }
 339
 340         /**
 341          * Validate an IP Block.
 342          * @return boolean True if it is valid.
 343          */
 344         public static function isValidBlock( $ipblock ) {
 345                 return ( count( self::toArray( $ipblock ) ) == 1 + 5 );
 346         }
 347
 348         /**
 349          * Determine if an IP address really is an IP address, and if it is public,
 350          * i.e. not RFC 1918 or similar
 351          * Comes from ProxyTools.php
 352          */
 353         public static function isPublic( $ip ) {
 354                 $n = self::toUnsigned( $ip );
 355                 if ( !$n ) {
 356                         return false;
 357                 }
 358
 359                 // ip2long accepts incomplete addresses, as well as some addresses
 360                 // followed by garbage characters. Check that it's really valid.
 361                 if( $ip != long2ip( $n ) ) {
 362                         return false;
 363                 }
 364
 365                 static $privateRanges = false;
 366                 if ( !$privateRanges ) {
 367                         $privateRanges = array(
 368                                 array( '10.0.0.0',    '10.255.255.255' ),   # RFC 1918 (private)
 369                                 array( '172.16.0.0',  '172.31.255.255' ),   #     "
 370                                 array( '192.168.0.0', '192.168.255.255' ),  #     "
 371                                 array( '0.0.0.0',     '0.255.255.255' ),    # this network
 372                                 array( '127.0.0.0',   '127.255.255.255' ),  # loopback
 373                         );
 374                 }
 375
 376                 foreach ( $privateRanges as $r ) {
 377                         $start = self::toUnsigned( $r[0] );
 378                         $end = self::toUnsigned( $r[1] );
 379                         if ( $n >= $start && $n <= $end ) {
 380                                 return false;
 381                         }
 382                 }
 383                 return true;
 384         }
 385
 386         /**
 387          * Split out an IP block as an array of 4 bytes and a mask,
 388          * return false if it can't be determined
 389          *
 390          * @param $ipblock string A quad dotted/octet IP address
 391          * @return array
 392          */
 393         public static function toArray( $ipblock ) {
 394                 $matches = array();
 395                 if( preg_match( '/^' . RE_IP_ADD . '(?:\/(?:' . RE_IP_PREFIX . '))?' . '$/', $ipblock, $matches ) ) {
 396                         return $matches;
 397                 } elseif ( preg_match( '/^' . RE_IPV6_ADD . '(?:\/(?:' . RE_IPV6_PREFIX . '))?' . '$/', $ipblock, $matches ) ) {
 398                         return $matches;
 399                 } else {
 400                         return false;
 401                 }
 402         }
 403
 404         /**
 405          * Return a zero-padded hexadecimal representation of an IP address.
 406          *
 407          * Hexadecimal addresses are used because they can easily be extended to
 408          * IPv6 support. To separate the ranges, the return value from this
 409          * function for an IPv6 address will be prefixed with "v6-", a non-
 410          * hexadecimal string which sorts after the IPv4 addresses.
 411          *
 412          * @param $ip Quad dotted/octet IP address.
 413          * @return hexidecimal
 414          */
 415         public static function toHex( $ip ) {
 416                 $n = self::toUnsigned( $ip );
 417                 if ( $n !== false ) {
 418                         $n = self::isIPv6( $ip ) ? 'v6-' . wfBaseConvert( $n, 10, 16, 32, false ) : wfBaseConvert( $n, 10, 16, 8, false );
 419                 }
 420                 return $n;
 421         }
 422
 423         /**
 424          * Given an IP address in dotted-quad/octet notation, returns an unsigned integer.
 425          * Like ip2long() except that it actually works and has a consistent error return value.
 426          * Comes from ProxyTools.php
 427          * @param $ip Quad dotted IP address.
 428          * @return integer
 429          */
 430         public static function toUnsigned( $ip ) {
 431                 // Use IPv6 functions if needed
 432                 if ( self::isIPv6( $ip ) ) {
 433                         return self::toUnsigned6( $ip );
 434                 }
 435                 if ( $ip == '255.255.255.255' ) {
 436                         $n = -1;
 437                 } else {
 438                         $n = ip2long( $ip );
 439                         if ( $n == -1 || $n === false ) { # Return value on error depends on PHP version
 440                                 $n = false;
 441                         }
 442                 }
 443                 if ( $n < 0 ) {
 444                         $n += pow( 2, 32 );
 445                 }
 446                 return $n;
 447         }
 448
 449         /**
 450          * Convert a dotted-quad IP to a signed integer
 451          * Returns false on failure
 452          */
 453         public static function toSigned( $ip ) {
 454                 if ( $ip == '255.255.255.255' ) {
 455                         $n = -1;
 456                 } else {
 457                         $n = ip2long( $ip );
 458                         if ( $n == -1 ) {
 459                                 $n = false;
 460                         }
 461                 }
 462                 return $n;
 463         }
 464
 465         /**
 466          * Convert a network specification in CIDR notation to an integer network and a number of bits
 467          * @return array(string, int)
 468          */
 469         public static function parseCIDR( $range ) {
 470                 $parts = explode( '/', $range, 2 );
 471                 if ( count( $parts ) != 2 ) {
 472                         return array( false, false );
 473                 }
 474                 $network = self::toSigned( $parts[0] );
 475                 if ( $network !== false && is_numeric( $parts[1] ) && $parts[1] >= 0 && $parts[1] <= 32 ) {
 476                         $bits = $parts[1];
 477                         if ( $bits == 0 ) {
 478                                 $network = 0;
 479                         } else {
 480                                 $network &= ~( ( 1 << ( 32 - $bits ) ) - 1);
 481                         }
 482                         # Convert to unsigned
 483                         if ( $network < 0 ) {
 484                                 $network += pow( 2, 32 );
 485                         }
 486                 } else {
 487                         $network = false;
 488                         $bits = false;
 489                 }
 490                 return array( $network, $bits );
 491         }
 492
 493         /**
 494          * Given a string range in a number of formats, return the start and end of
 495          * the range in hexadecimal.
 496          *
 497          * Formats are:
 498          *     1.2.3.4/24          CIDR
 499          *     1.2.3.4 - 1.2.3.5   Explicit range
 500          *     1.2.3.4             Single IP
 501          *
 502          *     2001:0db8:85a3::7344/96                                   CIDR
 503          *     2001:0db8:85a3::7344 - 2001:0db8:85a3::7344   Explicit range
 504          *     2001:0db8:85a3::7344                                      Single IP
 505          * @return array(string, int)
 506          */
 507         public static function parseRange( $range ) {
 508                 // Use IPv6 functions if needed
 509                 if ( self::isIPv6( $range ) ) {
 510                         return self::parseRange6( $range );
 511                 }
 512                 if ( strpos( $range, '/' ) !== false ) {
 513                         # CIDR
 514                         list( $network, $bits ) = self::parseCIDR( $range );
 515                         if ( $network === false ) {
 516                                 $start = $end = false;
 517                         } else {
 518                                 $start = sprintf( '%08X', $network );
 519                                 $end = sprintf( '%08X', $network + pow( 2, ( 32 - $bits ) ) - 1 );
 520                         }
 521                 } elseif ( strpos( $range, '-' ) !== false ) {
 522                         # Explicit range
 523                         list( $start, $end ) = array_map( 'trim', explode( '-', $range, 2 ) );
 524                         if( self::isIPAddress( $start ) && self::isIPAddress( $end ) ) {
 525                                 $start = self::toUnsigned( $start );
 526                                 $end = self::toUnsigned( $end );
 527                                 if ( $start > $end ) {
 528                                         $start = $end = false;
 529                                 } else {
 530                                         $start = sprintf( '%08X', $start );
 531                                         $end = sprintf( '%08X', $end );
 532                                 }
 533                         } else {
 534                                 $start = $end = false;
 535                         }
 536                 } else {
 537                         # Single IP
 538                         $start = $end = self::toHex( $range );
 539                 }
 540                 if ( $start === false || $end === false ) {
 541                         return array( false, false );
 542                 } else {
 543                         return array( $start, $end );
 544                 }
 545         }
 546
 547         /**
 548          * Determine if a given IPv4/IPv6 address is in a given CIDR network
 549          * @param $addr The address to check against the given range.
 550          * @param $range The range to check the given address against.
 551          * @return bool Whether or not the given address is in the given range.
 552          */
 553         public static function isInRange( $addr, $range ) {
 554                 // Convert to IPv6 if needed
 555                 $hexIP = self::toHex( $addr );
 556                 list( $start, $end ) = self::parseRange( $range );
 557                 return ( strcmp( $hexIP, $start ) >= 0 &&
 558                         strcmp( $hexIP, $end ) <= 0 );
 559         }
 560
 561         /**
 562          * Convert some unusual representations of IPv4 addresses to their
 563          * canonical dotted quad representation.
 564          *
 565          * This currently only checks a few IPV4-to-IPv6 related cases.  More
 566          * unusual representations may be added later.
 567          *
 568          * @param $addr something that might be an IP address
 569          * @return valid dotted quad IPv4 address or null
 570          */
 571         public static function canonicalize( $addr ) {
 572                 if ( self::isValid( $addr ) ) {
 573                         return $addr;
 574                 }
 575
 576                 // Turn mapped addresses from ::ce:ffff:1.2.3.4 to 1.2.3.4
 577                 if ( strpos( $addr, ':' ) !== false && strpos( $addr, '.' ) !== false ) {
 578                         $addr = substr( $addr, strrpos( $addr, ':' ) + 1 );
 579                         if( self::isIPv4( $addr ) ) {
 580                                 return $addr;
 581                         }
 582                 }
 583
 584                 // IPv6 loopback address
 585                 $m = array();
 586                 if ( preg_match( '/^0*' . RE_IPV6_GAP . '1$/', $addr, $m ) ) {
 587                         return '127.0.0.1';
 588                 }
 589
 590                 // IPv4-mapped and IPv4-compatible IPv6 addresses
 591                 if ( preg_match( '/^' . RE_IPV6_V4_PREFIX . '(' . RE_IP_ADD . ')$/i', $addr, $m ) ) {
 592                         return $m[1];
 593                 }
 594                 if ( preg_match( '/^' . RE_IPV6_V4_PREFIX . RE_IPV6_WORD . ':' . RE_IPV6_WORD . '$/i', $addr, $m ) ) {
 595                         return long2ip( ( hexdec( $m[1] ) << 16 ) + hexdec( $m[2] ) );
 596                 }
 597
 598                 return null;  // give up
 599         }
 600 }