IP range vs IP check

<?php
// 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 - Using substr to chop up the range and pad it with 1s to the right
      $broadcast_dec = bindec(substr(decbin32($range_dec), 0, $netmask) 
                            . str_pad('', 32-$netmask, '1'));

      # Strategy 2 - Use math to OR the range with the wildcard to create the Broadcast address
      $wildcard_dec = pow(2, (32-$netmask)) - 1;
      $broadcast_dec = $range_dec | $wildcard_dec;

      return (($ip_dec & $broadcast_dec) == $ip_dec);
    }
  } else {
    // range might be 255.255.*.* or 1.2.3.0-1.2.3.255
    if (strpos($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);
      $lower_dec = ip2long($lower);
      $upper_dec = ip2long($upper);
      $ip_dec = ip2long($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;
  }

  $ip_dec = ip2long($ip);
  printf("ip_dec       = %s\n", decbin32($ip_dec));
  printf("netmask_dec  = %s\n", decbin32($netmask_dec));
  printf("ANDed        = %s\n", decbin32(($ip_dec & $netmask_dec)));
  return (($ip_dec & $netmask_dec) == $ip_dec);
}
?>

<?php
// 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 - Using substr to chop up the range and pad it with 1s to the right
      $broadcast_dec = bindec(substr(decbin32($range_dec), 0, $netmask) 
                            . str_pad('', 32-$netmask, '1'));
 
      # Strategy 2 - Use math to OR the range with the wildcard to create the Broadcast address
      $wildcard_dec = pow(2, (32-$netmask)) - 1;
      $broadcast_dec = $range_dec | $wildcard_dec;
 
      return (($ip_dec & $broadcast_dec) == $ip_dec);
    }
  } else {
    // range might be 255.255.*.* or 1.2.3.0-1.2.3.255
    if (strpos($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);
      $lower_dec = ip2long($lower);
      $upper_dec = ip2long($upper);
      $ip_dec = ip2long($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;
  }
 
  $ip_dec = ip2long($ip);
  printf("ip_dec       = %s\n", decbin32($ip_dec));
  printf("netmask_dec  = %s\n", decbin32($netmask_dec));
  printf("ANDed        = %s\n", decbin32(($ip_dec & $netmask_dec)));
  return (($ip_dec & $netmask_dec) == $ip_dec);
}
?>