Planet CakePHP

Let’s say we need to build a list of network addresses to whitelist access to a restricted area, or blacklist a troublesome spammer. It’s handy to be able to enter data in a variety of formats, including hostnames, IP addresses, and IP ranges.
Usually we will store this information as a long, then we can easily see if a requesting IP address falls within our list of networks simply by numerical comparison, specifically: start_range < requesting_ip < end_range.
However, our user doesn't want to enter the list of IPs as a long so we need tools to convert between an attractive input format, and an array of start and end ranges.
To accomplish this, we define two functions network_expand_range and network_compact_range. Let’s have a look:

/**
* Take small human readable network and give dotted quad range
*
* Acceptable inputs:
* 1.1.1.1 - 1.1.255.255
* 2.2.2.0-255
* 3.3.3.*
* 4.4.*.*
* 5.5.5.20-40
* google.com
*
* @author Aidan Lister
* @link http://aidanlister.com/2009/10/dealing-with-human-readable-network-addre...
* @param input $string A newline separated list of network ranges
* @return array Start and end addresses in dotted quads, or false
*/
function network_expand_range($network)
{
// Sanity check
if (empty($network)) {
return false;
}

$has_star = strpos($network, '*');
$has_dash = strpos($network, '-');

// Last character of a domain must be in the alphabet
if (ctype_alpha($network[strlen($network)-1])) {
if (!$address = gethostbyname($network)) {
return false;
}
return array($address, $address);
}

// Simple
if ($has_star === false && $has_dash === false) {
$res = long2ip(ip2long($network));
$start = $end = $res;
if ($res === '0.0.0.0') {
return false;
}
}

// Using a star
if ($has_star !== false) {
$start = long2ip(ip2long(str_replace('*', '0', $network)));
$end = long2ip(ip2long(str_replace('*', '255', $network)));
if ($start === '0.0.0.0' || $end === '0.0.0.0') {
return false;
}
}

// Using a dash
if ($has_dash !== false) {
list($start, $end) = explode('-', $network);

// Check whether end is a full IP or just the last quad
if (strpos($end, '.') !== false) {
$end = long2ip(ip2long(trim($end)));
} else {
// Get the first 3 quads of the start address
$classc = substr($start, 0, strrpos($start, '.'));
$classc .= '.' . $end;
$end = long2ip(ip2long(trim($classc)));
}

// Check for failure
$start = long2ip(ip2long(trim($start)));
if ($start === '0.0.0.0' || $end === '0.0.0.0') {
return false;
}
}

return array($start, $end);
}

Next, the sister function to reverse the expansion process:

/**
* Convert start and end address into small human readable string
*
* For example, $s=1.1.1.1 and $e=1.1.255.255 into 1.1.*.*
*
* @author Aidan Lister
* @link http://aidanlister.com/2009/10/dealing-with-human-readable-network-addre...
* @param int $start The start address
* @param int $end The end address
* @return string A start and end range as the small formatted string
*/
function network_compact_range($start, $end)
{
if ($start === $end) {
$output = $start;
} else {
$s = explode('.', $start);
$e = explode('.', $end);
if ($s[0] === $e[0] && $s[1] === $e[1] && $s[2] === $e[2]) {
if ($s[3] === '0' && $e[3] === '255') {
$s[3] = '*';
$output = implode('.', $s);
} else {
$s[3] = sprintf('%s-%s', $s[3], $e[3]);
$output = implode('.', $s);
}
} else {
$output = $start .' - '. $end;
}
}

return $output;
}

To show how it all works, let’s look at some examples:

// Example input (maybe from a textarea, database or file)
$input = array();
$input[] = '1.1.1.1 - 1.1.255.255';
$input[] = '2.2.2.0-255';
$input[] = '3.3.3.*';
$input[] = '4.4.*.*';
$input[] = '5.5.5.20-40';
$input[] = 'google.com';

echo "The input is:\n";
foreach ($input as $network) {
echo "$network\n";
}

echo "\n";
echo "Expanded into ranges:\n";
foreach ($input as $network) {
list($start, $end) = network_expand_range($network);
echo "$start - $end\n";
}

echo "\n";
echo "As a long:\n";
foreach ($input as $network) {
list($start, $end) = network_expand_range($network);
echo ip2long($start) . ' - ' . ip2long($end) . "\n";
}

echo "\n";
echo "Back into compacted form:\n";
foreach ($input as $network) {
list($start, $end) = network_expand_range($network);
echo network_compact_range($start, $end), "\n";
}

The output of this would be something like:

The input is:
1.1.1.1 - 1.1.255.255
2.2.2.0-255
3.3.3.*
4.4.*.*
5.5.5.20-40
google.com

Expanded into ranges:
1.1.1.1 - 1.1.255.255
2.2.2.0 - 2.2.2.255
3.3.3.0 - 3.3.3.255
4.4.0.0 - 4.4.255.255
5.5.5.20 - 5.5.5.40
74.125.53.100 - 74.125.53.100

As a long:
16843009 - 16908287
33686016 - 33686271
50529024 - 50529279
67371008 - 67436543
84215060 - 84215080
1249719652 - 1249719652

Back into compacted form:
1.1.1.1 - 1.1.255.255
2.2.2.*
3.3.3.*
4.4.0.0 - 4.4.255.255
5.5.5.20-40
74.125.53.100

Hope you find this useful.