Working with IPv6 Addresses in PHP

Question

After searching around somewhat thoroughly, I noticed a slight lack of functions in PHP for handling IPv6. For my own personal satisfaction I created a few functions to help the transition.

The IPv6ToLong() function is a temporary solution to that brought up here: How to store IPv6-compatible address in a relational database. It will split the IP in to two integers and return them in an array.

/**
 * Convert an IPv4 address to IPv6
 *
 * @param string IP Address in dot notation (192.168.1.100)
 * @return string IPv6 formatted address or false if invalid input
 */
function IPv4To6($Ip) {
    static $Mask = '::ffff:'; // This tells IPv6 it has an IPv4 address
    $IPv6 = (strpos($Ip, '::') === 0);
    $IPv4 = (strpos($Ip, '.') > 0);

    if (!$IPv4 && !$IPv6) return false;
    if ($IPv6 && $IPv4) $Ip = substr($Ip, strrpos($Ip, ':')+1); // Strip IPv4 Compatibility notation
    elseif (!$IPv4) return $Ip; // Seems to be IPv6 already?
    $Ip = array_pad(explode('.', $Ip), 4, 0);
    if (count($Ip) > 4) return false;
    for ($i = 0; $i < 4; $i++) if ($Ip[$i] > 255) return false;

    $Part7 = base_convert(($Ip[0] * 256) + $Ip[1], 10, 16);
    $Part8 = base_convert(($Ip[2] * 256) + $Ip[3], 10, 16);
    return $Mask.$Part7.':'.$Part8;
}

/**
 * Replace '::' with appropriate number of ':0'
 */
function ExpandIPv6Notation($Ip) {
    if (strpos($Ip, '::') !== false)
     $Ip = str_replace('::', str_repeat(':0', 8 - substr_count($Ip, ':')).':', $Ip);
    if (strpos($Ip, ':') === 0) $Ip = '0'.$Ip;
    return $Ip;
}

/**
 * Convert IPv6 address to an integer
 *
 * Optionally split in to two parts.
 *
 * @see http://stackoverflow.com/questions/420680/
 */
function IPv6ToLong($Ip, $DatabaseParts= 2) {
    $Ip = ExpandIPv6Notation($Ip);
    $Parts = explode(':', $Ip);
    $Ip = array('', '');
    for ($i = 0; $i < 4; $i++) $Ip[0] .= str_pad(base_convert($Parts[$i], 16, 2), 16, 0, STR_PAD_LEFT);
    for ($i = 4; $i < 8; $i++) $Ip[1] .= str_pad(base_convert($Parts[$i], 16, 2), 16, 0, STR_PAD_LEFT);

    if ($DatabaseParts == 2)
            return array(base_convert($Ip[0], 2, 10), base_convert($Ip[1], 2, 10));
    else    return base_convert($Ip[0], 2, 10) + base_convert($Ip[1], 2, 10);
}

For these functions I typically implement them by calling this function first:

/**
 * Attempt to find the client's IP Address
 *
 * @param bool Should the IP be converted using ip2long?
 * @return string|long The IP Address
 */
function GetRealRemoteIp($ForDatabase= false, $DatabaseParts= 2) {
    $Ip = '0.0.0.0';
    if (isset($_SERVER['HTTP_CLIENT_IP']) && $_SERVER['HTTP_CLIENT_IP'] != '')
     $Ip = $_SERVER['HTTP_CLIENT_IP'];
    elseif (isset($_SERVER['HTTP_X_FORWARDED_FOR']) && $_SERVER['HTTP_X_FORWARDED_FOR'] != '')
     $Ip = $_SERVER['HTTP_X_FORWARDED_FOR'];
    elseif (isset($_SERVER['REMOTE_ADDR']) && $_SERVER['REMOTE_ADDR'] != '')
     $Ip = $_SERVER['REMOTE_ADDR'];
    if (($CommaPos = strpos($Ip, ',')) > 0)
     $Ip = substr($Ip, 0, ($CommaPos - 1));

    $Ip = IPv4To6($Ip);
    return ($ForDatabase ? IPv6ToLong($Ip, $DatabaseParts) : $Ip);
}

Someone please tell me if I'm reinventing the wheel here or I've done something wrong.

This implementation converts IPv4 to IPv6. Any IPv6 address it doesn't touch.

Answer 1

PHP.net's Filter extension contains some constants for matching IPv4 and IPv6 addresses, which might be useful for checking the address. I haven't seen any conversion utilities though.

Answer 2

How about inet_ntop()? Then instead of chopping things into integers, you just use a varbinary(16) to store it.

Answer 3

You could also store the address in a binary(16) in mysql, so you should have an option to output it in binary from IPv6ToLong().

This is really something that need to be added natively in PHP, especially when many IPv6 enabled web-servers report ::FFFF:1.2.3.4 as the client IP and it's incompatible with ip2long, and will break alot of stuff.