<?php
/**
 * Piwik - free/libre analytics platform
 *
 * @link http://piwik.org
 * @license http://www.gnu.org/licenses/lgpl-3.0.html LGPL v3 or later
 */

namespace Piwik\Network;

/**
 * IP address utilities (for both IPv4 and IPv6).
 *
 * As a matter of naming convention, we use `$ip` for the binary format (network address format)
 * and `$ipString` for the string/presentation format (i.e., human-readable form).
 */
class IPUtils
{
    /**
     * Removes the port and the last portion of a CIDR IP address.
     *
     * @param string $ipString The IP address to sanitize.
     * @return string
     */
    public static function sanitizeIp($ipString)
    {
        $ipString = trim($ipString);

        // CIDR notation, A.B.C.D/E
        $posSlash = strrpos($ipString, '/');
        if ($posSlash !== false) {
            $ipString = substr($ipString, 0, $posSlash);
        }

        $posColon = strrpos($ipString, ':');
        $posDot = strrpos($ipString, '.');
        if ($posColon !== false) {
            // IPv6 address with port, [A:B:C:D:E:F:G:H]:EEEE
            $posRBrac = strrpos($ipString, ']');
            if ($posRBrac !== false && $ipString[0] == '[') {
                $ipString = substr($ipString, 1, $posRBrac - 1);
            }

            if ($posDot !== false) {
                // IPv4 address with port, A.B.C.D:EEEE
                if ($posColon > $posDot) {
                    $ipString = substr($ipString, 0, $posColon);
                }
                // else: Dotted quad IPv6 address, A:B:C:D:E:F:G.H.I.J
            } else if (strpos($ipString, ':') === $posColon) {
                $ipString = substr($ipString, 0, $posColon);
            }
            // else: IPv6 address, A:B:C:D:E:F:G:H
        }
        // else: IPv4 address, A.B.C.D

        return $ipString;
    }

    /**
     * Sanitize human-readable (user-supplied) IP address range.
     *
     * Accepts the following formats for $ipRange:
     * - single IPv4 address, e.g., 127.0.0.1
     * - single IPv6 address, e.g., ::1/128
     * - IPv4 block using CIDR notation, e.g., 192.168.0.0/22 represents the IPv4 addresses from 192.168.0.0 to 192.168.3.255
     * - IPv6 block using CIDR notation, e.g., 2001:DB8::/48 represents the IPv6 addresses from 2001:DB8:0:0:0:0:0:0 to 2001:DB8:0:FFFF:FFFF:FFFF:FFFF:FFFF
     * - wildcards, e.g., 192.168.0.* or 2001:DB8:*:*:*:*:*:*
     *
     * @param string $ipRangeString IP address range
     * @return string|null  IP address range in CIDR notation OR null on failure
     */
    public static function sanitizeIpRange($ipRangeString)
    {
        $ipRangeString = trim($ipRangeString);
        if (empty($ipRangeString)) {
            return null;
        }

        // IP address with wildcards '*'
        if (strpos($ipRangeString, '*') !== false) {
            // Disallow prefixed wildcards and anything other than wildcards
            // and separators (including IPv6 zero groups) after first wildcard
            if (preg_match('/[^.:]\*|\*.*([^.:*]|::)/', $ipRangeString)) {
                return null;
            }

            $numWildcards = substr_count($ipRangeString, '*');
            $ipRangeString = str_replace('*', '0', $ipRangeString);

        // CIDR
        } elseif (($pos = strpos($ipRangeString, '/')) !== false) {
            $bits = substr($ipRangeString, $pos + 1);
            $ipRangeString = substr($ipRangeString, 0, $pos);

            if (!is_numeric($bits)) {
                return null;
            }
        }

        // single IP
        if (($ip = @inet_pton($ipRangeString)) === false)
            return null;

        $maxbits = strlen($ip) * 8;
        if (!isset($bits)) {
            $bits = $maxbits;

            if (isset($numWildcards)) {
                $bits -= ($maxbits === 32 ? 8 : 16) * $numWildcards;
            }
        }

        if ($bits < 0 || $bits > $maxbits) {
            return null;
        }

        return "$ipRangeString/$bits";
    }

    /**
     * Converts an IP address in string/presentation format to binary/network address format.
     *
     * @param string $ipString IP address, either IPv4 or IPv6, e.g. `'127.0.0.1'`.
     * @return string Binary-safe string, e.g. `"\x7F\x00\x00\x01"`.
     */
    public static function stringToBinaryIP($ipString)
    {
        // use @inet_pton() because it throws an exception and E_WARNING on invalid input
        $ip = @inet_pton($ipString);
        return $ip === false ? "\x00\x00\x00\x00" : $ip;
    }

    /**
     * Convert binary/network address format to string/presentation format.
     *
     * @param string $ip IP address in binary/network address format, e.g. `"\x7F\x00\x00\x01"`.
     * @return string IP address in string format, e.g. `'127.0.0.1'`.
     */
    public static function binaryToStringIP($ip)
    {
        // use @inet_ntop() because it throws an exception and E_WARNING on invalid input
        $ipStr = @inet_ntop($ip);
        return $ipStr === false ? '0.0.0.0' : $ipStr;
    }

    /**
     * Get low and high IP addresses for a specified IP range.
     *
     * @param string $ipRange An IP address range in string format, e.g. `'192.168.1.1/24'`.
     * @return array|null Array `array($lowIp, $highIp)` in binary format, or null on failure.
     */
    public static function getIPRangeBounds($ipRange)
    {
        $ipRange = self::sanitizeIpRange($ipRange);

        if ($ipRange === null ||
            (($pos = strpos($ipRange, '/')) === false) ||
            ($pos + 1 === strlen($ipRange))
        ) {
            return null;
        }

        $range = substr($ipRange, 0, $pos);
        $high  = $low = @inet_pton($range);

        if ($low === false) {
            return null;
        }

        $addrLen = strlen($low);
        $bits   = (int) substr($ipRange, $pos + 1);

        if ($bits < 0 || $bits > $addrLen * 8) {
            return null;
        }

        $octet = (int) (($bits + 7) / 8);

        for ($i = $octet; $i < $addrLen; $i++) {
            $low[$i]  = chr(0);
            $high[$i] = chr(255);
        }

        if (($n = $bits % 8)) {
            $mask  = (1 << (8 - $n)) - 1;
            $value = ord($low[--$octet]) & ~$mask;

            $low[$octet]  = chr($value);
            $high[$octet] = chr($value | $mask);
        }

        return array($low, $high);
    }
}
