IP in range (PHP)

<?php

/*
 * ip_in_range.php - Function to determine if an IP is located in a
 *                   specific range as specified via several alternative
 *                   formats.
 *
 * Network ranges can be specified as:
 * 1. Wildcard format:     1.2.3.*
 * 2. CIDR format:         1.2.3/24  OR  1.2.3.4/255.255.255.0
 * 3. Start-End IP format: 1.2.3.0-1.2.3.255
 *
 * Return value BOOLEAN : ip_in_range($ip, $range);
 *
 * Copyright 2008: Paul Gregg <pgregg@pgregg.com>
 * 10 January 2008
 * Version: 1.2
 *
 * Source website: http://www.pgregg.com/projects/php/ip_in_range/
 * Version 1.2
 *
 * This software is Donationware - if you feel you have benefited from
 * the use of this tool then please consider a donation. The value of
 * which is entirely left up to your discretion.
 * http://www.pgregg.com/donate/
 *
 * Please do not remove this header, or source attibution from this file.
 */


// decbin32
// In order to simplify working with IP addresses (in binary) and their
// netmasks, it is easier to ensure that the binary strings are padded
// with zeros out to 32 characters - IP addresses are 32 bit numbers
Function decbin32 ($dec) {
  return str_pad(decbin($dec), 32, '0', STR_PAD_LEFT);
}

// ip_in_range
// This function takes 2 arguments, an IP address and a "range" in several
// different formats.
// Network ranges can be specified as:
// 1. Wildcard format:     1.2.3.*
// 2. CIDR format:         1.2.3/24  OR  1.2.3.4/255.255.255.0
// 3. Start-End IP format: 1.2.3.0-1.2.3.255
// The function will return true if the supplied IP is within the range.
// Note little validation is done on the range inputs - it expects you to
// use one of the above 3 formats.
Function ip_in_range($ip, $range) {
  if (strpos($range, '/') !== false) {
    // $range is in IP/NETMASK format
    list($range, $netmask) = explode('/', $range, 2);
    if (strpos($netmask, '.') !== false) {
      // $netmask is a 255.255.0.0 format
      $netmask = str_replace('*', '0', $netmask);
      $netmask_dec = ip2long($netmask);
      return ( (ip2long($ip) & $netmask_dec) == (ip2long($range) & $netmask_dec) );
    } else {
      // $netmask is a CIDR size block
      // fix the range argument
      $x = explode('.', $range);
      while(count($x)<4) $x[] = '0';
      list($a,$b,$c,$d) = $x;
      $range = sprintf("%u.%u.%u.%u", empty($a)?'0':$a, empty($b)?'0':$b,empty($c)?'0':$c,empty($d)?'0':$d);
      $range_dec = ip2long($range);
      $ip_dec = ip2long($ip);

      # Strategy 1 - Create the netmask with 'netmask' 1s and then fill it to 32 with 0s
      #$netmask_dec = bindec(str_pad('', $netmask, '1') . str_pad('', 32-$netmask, '0'));

      # Strategy 2 - Use math to create it
      $wildcard_dec = pow(2, (32-$netmask)) - 1;
      $netmask_dec = ~ $wildcard_dec;

      return (($ip_dec & $netmask_dec) == ($range_dec & $netmask_dec));
    }
  } else {
    // range might be 255.255.*.* or 1.2.3.0-1.2.3.255
    if (strpos($range, '*') !==false) { // a.b.*.* format
      // Just convert to A-B format by setting * to 0 for A and 255 for B
      $lower = str_replace('*', '0', $range);
      $upper = str_replace('*', '255', $range);
      $range = "$lower-$upper";
    }

    if (strpos($range, '-')!==false) { // A-B format
      list($lower, $upper) = explode('-', $range, 2);
      $lower_dec = (float)sprintf("%u",ip2long($lower));
      $upper_dec = (float)sprintf("%u",ip2long($upper));
      $ip_dec = (float)sprintf("%u",ip2long($ip));
      return ( ($ip_dec>=$lower_dec) && ($ip_dec<=$upper_dec) );
    }

    echo 'Range argument is not in 1.2.3.4/24 or 1.2.3.4/255.255.255.0 format';
    return false;
  }

}
?>