<?php
/**
 * Utils class file.
 *
 * @package automattic/jetpack-ip
 */

namespace Automattic\Jetpack\IP;

/**
 * Class that provides static methods for working with IP addresses.
 */
class Utils {

	const PACKAGE_VERSION = '0.2.1';

	/**
	 * Get the current user's IP address.
	 *
	 * @return string|false IP address.
	 */
	public static function get_ip() {
		$trusted_header_data = get_site_option( 'trusted_ip_header' );
		if ( isset( $trusted_header_data->trusted_header ) && isset( $_SERVER[ $trusted_header_data->trusted_header ] ) ) {
			$ip            = wp_unslash( $_SERVER[ $trusted_header_data->trusted_header ] ); // phpcs:ignore WordPress.Security.ValidatedSanitizedInput.InputNotSanitized -- clean_ip does it below.
			$segments      = $trusted_header_data->segments;
			$reverse_order = $trusted_header_data->reverse;
		} else {
			$ip = isset( $_SERVER['REMOTE_ADDR'] ) ? wp_unslash( $_SERVER['REMOTE_ADDR'] ) : null; // phpcs:ignore WordPress.Security.ValidatedSanitizedInput.InputNotSanitized -- clean_ip does it below.
		}

		if ( ! $ip ) {
			return false;
		}

		$ips = explode( ',', $ip );
		if ( ! isset( $segments ) || ! $segments ) {
			$segments = 1;
		}
		if ( isset( $reverse_order ) && $reverse_order ) {
			$ips = array_reverse( $ips );
		}
		$ip_count = count( $ips );
		if ( 1 === $ip_count ) {
			return self::clean_ip( $ips[0] );
		} elseif ( $ip_count >= $segments ) {
			$the_one = $ip_count - $segments;
			return self::clean_ip( $ips[ $the_one ] );
		} else {
			return self::clean_ip( isset( $_SERVER['REMOTE_ADDR'] ) ? wp_unslash( $_SERVER['REMOTE_ADDR'] ) : null ); // phpcs:ignore WordPress.Security.ValidatedSanitizedInput.InputNotSanitized -- clean_ip does it.
		}
	}

	/**
	 * Clean IP address.
	 *
	 * @param string $ip The IP address to clean.
	 * @return string|false The cleaned IP address.
	 */
	public static function clean_ip( $ip ) {

		// Some misconfigured servers give back extra info, which comes after "unless".
		$ips = explode( ' unless ', $ip );
		$ip  = $ips[0];

		$ip = strtolower( trim( $ip ) );

		// Check for IPv4 with port.
		if ( preg_match( '/^(\d+\.\d+\.\d+\.\d+):\d+$/', $ip, $matches ) ) {
			$ip = $matches[1];
		}

		// Check for IPv6 (or IPvFuture) with brackets and optional port.
		if ( preg_match( '/^\[([a-z0-9\-._~!$&\'()*+,;=:]+)\](?::\d+)?$/', $ip, $matches ) ) {
			$ip = $matches[1];
		}

		// Check for IPv4 IP cast as IPv6.
		if ( preg_match( '/^::ffff:(\d+\.\d+\.\d+\.\d+)$/', $ip, $matches ) ) {
			$ip = $matches[1];
		}

		// Validate and return.
		return filter_var( $ip, FILTER_VALIDATE_IP ) ? $ip : false;
	}

	/**
	 * Checks an IP to see if it is within a private range.
	 *
	 * @param int $ip IP address.
	 * @return bool True if IP address is private, false otherwise.
	 */
	public static function ip_is_private( $ip ) {
		// We are dealing with ipv6, so we can simply rely on filter_var.
		// Note: str_contains() is not used here, as wp-includes/compat.php may not be loaded in this file.
		if ( false === strpos( $ip, '.' ) ) {
			return ! filter_var( $ip, FILTER_VALIDATE_IP, FILTER_FLAG_NO_PRIV_RANGE | FILTER_FLAG_NO_RES_RANGE );
		}
		// We are dealing with ipv4.
		$private_ip4_addresses = array(
			'10.0.0.0|10.255.255.255',     // Single class A network.
			'172.16.0.0|172.31.255.255',   // 16 contiguous class B network.
			'192.168.0.0|192.168.255.255', // 256 contiguous class C network.
			'169.254.0.0|169.254.255.255', // Link-local address also referred to as Automatic Private IP Addressing.
			'127.0.0.0|127.255.255.255',    // localhost.
		);
		$long_ip               = ip2long( $ip );
		if ( -1 !== $long_ip ) {
			foreach ( $private_ip4_addresses as $pri_addr ) {
				list ( $start, $end ) = explode( '|', $pri_addr );
				if ( $long_ip >= ip2long( $start ) && $long_ip <= ip2long( $end ) ) {
					return true;
				}
			}
		}
		return false;
	}

	/**
	 * Uses inet_pton if available to convert an IP address to a binary string.
	 * Returns false if an invalid IP address is given.
	 *
	 * @param mixed $ip IP address.
	 * @return int|string|bool
	 */
	public static function convert_ip_address( $ip ) {
		return inet_pton( $ip );
	}

	/**
	 * Checks that a given IP address is within a given low - high range.
	 *
	 * @param mixed $ip IP.
	 * @param mixed $range_low Range Low.
	 * @param mixed $range_high Range High.
	 * @return Bool
	 */
	public static function ip_address_is_in_range( $ip, $range_low, $range_high ) {
		$ip_num  = inet_pton( $ip );
		$ip_low  = inet_pton( $range_low );
		$ip_high = inet_pton( $range_high );
		if ( $ip_num && $ip_low && $ip_high && strcmp( $ip_num, $ip_low ) >= 0 && strcmp( $ip_num, $ip_high ) <= 0 ) {
			return true;
		}
		return false;
	}

	/**
	 * Extracts IP addresses from a given string.
	 *
	 * We allow for both, one IP per line or comma-; semicolon; or whitespace-separated lists. This also validates the IP addresses
	 * and only returns the ones that look valid. IP ranges using the "-" character are also supported.
	 *
	 * @param string $ips List of ips - example: "8.8.8.8\n4.4.4.4,2.2.2.2;1.1.1.1 9.9.9.9,5555.5555.5555.5555,1.1.1.10-1.1.1.20".
	 * @return array List of valid IP addresses. - example based on input example: array('8.8.8.8', '4.4.4.4', '2.2.2.2', '1.1.1.1', '9.9.9.9', '1.1.1.10-1.1.1.20')
	 */
	public static function get_ip_addresses_from_string( $ips ) {
		$ips = (string) $ips;
		$ips = preg_split( '/[\s,;]/', $ips );

		$result = array();

		foreach ( $ips as $ip ) {
			// Validate both IP values from the range.
			$range = explode( '-', $ip );
			if ( count( $range ) === 2 ) {
				if ( self::validate_ip_range( $range[0], $range[1] ) ) {
					$result[] = $ip;
				}
				continue;
			}

			// Validate the single IP value.
			if ( filter_var( $ip, FILTER_VALIDATE_IP ) !== false ) {
				$result[] = $ip;
			}
		}

		return $result;
	}

	/**
	 * Validates the low and high IP addresses of a range.
	 *
	 * @param string $range_low  Low IP address.
	 * @param string $range_high High IP address.
	 * @return bool True if the range is valid, false otherwise.
	 */
	public static function validate_ip_range( $range_low, $range_high ) {
		// Validate that both IP addresses are valid.
		if ( ! filter_var( $range_low, FILTER_VALIDATE_IP ) || ! filter_var( $range_high, FILTER_VALIDATE_IP ) ) {
			return false;
		}

		// Validate that the $range_low is lower or equal to $range_high.
		// The inet_pton will give us binary string of an ipv4 or ipv6.
		// We can then use strcmp to see if the address is in range.
		$ip_low  = inet_pton( $range_low );
		$ip_high = inet_pton( $range_high );
		if ( false === $ip_low || false === $ip_high ) {
			return false;
		}
		if ( strcmp( $ip_low, $ip_high ) > 0 ) {
			return false;
		}

		return true;
	}
}