Dealing with human readable network addresses

<?php
/**
 * 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 <aidan@php.net>
 * @link http://aidanlister.com/2009/10/dealing-with-human-readable-network-addresses/
 * @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);
}
?>

<?php
/**
 * 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 <aidan@php.net>
 * @link http://aidanlister.com/2009/10/dealing-with-human-readable-network-addresses/
 * @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;
}
?>

<?php
// 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";
}
?>