<?php

/**

 * SSL utilities for Requests

 *

 * @package Requests

 * @subpackage Utilities

 */

/**

 * SSL utilities for Requests

 *

 * Collection of utilities for working with and verifying SSL certificates.

 *

 * @package Requests

 * @subpackage Utilities

 */

class Requests_SSL {

	/**

	 * Verify the certificate against common name and subject alternative names

	 *

	 * Unfortunately, PHP doesn't check the certificate against the alternative

	 * names, leading things like 'https://www.github.com/' to be invalid.

	 *

	 * @see https://tools.ietf.org/html/rfc2818#section-3.1 RFC2818, Section 3.1

	 *

	 * @throws Requests_Exception On not obtaining a match for the host (`fsockopen.ssl.no_match`)

	 * @param string $host Host name to verify against

	 * @param array $cert Certificate data from openssl_x509_parse()

	 * @return bool

	 */

	public static function verify_certificate($host, $cert) {

		$has_dns_alt = false;

		// Check the subjectAltName

		if (!empty($cert['extensions']) && !empty($cert['extensions']['subjectAltName'])) {

			$altnames = explode(',', $cert['extensions']['subjectAltName']);

			foreach ($altnames as $altname) {

				$altname = trim($altname);

				if (strpos($altname, 'DNS:') !== 0) {

					continue;

				}

				$has_dns_alt = true;

				// Strip the 'DNS:' prefix and trim whitespace

				$altname = trim(substr($altname, 4));

				// Check for a match

				if (self::match_domain($host, $altname) === true) {

					return true;

				}

			}

		}

		// Fall back to checking the common name if we didn't get any dNSName

		// alt names, as per RFC2818

		if (!$has_dns_alt && !empty($cert['subject']['CN'])) {

			// Check for a match

			if (self::match_domain($host, $cert['subject']['CN']) === true) {

				return true;

			}

		}

		return false;

	}

	/**

	 * Verify that a reference name is valid

	 *

	 * Verifies a dNSName for HTTPS usage, (almost) as per Firefox's rules:

	 * - Wildcards can only occur in a name with more than 3 components

	 * - Wildcards can only occur as the last character in the first

	 *   component

	 * - Wildcards may be preceded by additional characters

	 *

	 * We modify these rules to be a bit stricter and only allow the wildcard

	 * character to be the full first component; that is, with the exclusion of

	 * the third rule.

	 *

	 * @param string $reference Reference dNSName

	 * @return boolean Is the name valid?

	 */

	public static function verify_reference_name($reference) {

		$parts = explode('.', $reference);

		// Check the first part of the name

		$first = array_shift($parts);

		if (strpos($first, '*') !== false) {

			// Check that the wildcard is the full part

			if ($first !== '*') {

				return false;

			}

			// Check that we have at least 3 components (including first)

			if (count($parts) < 2) {

				return false;

			}

		}

		// Check the remaining parts

		foreach ($parts as $part) {

			if (strpos($part, '*') !== false) {

				return false;

			}

		}

		// Nothing found, verified!

		return true;

	}

	/**

	 * Match a hostname against a dNSName reference

	 *

	 * @param string $host Requested host

	 * @param string $reference dNSName to match against

	 * @return boolean Does the domain match?

	 */

	public static function match_domain($host, $reference) {

		// Check if the reference is blocklisted first

		if (self::verify_reference_name($reference) !== true) {

			return false;

		}

		// Check for a direct match

		if ($host === $reference) {

			return true;

		}

		// Calculate the valid wildcard match if the host is not an IP address

		// Also validates that the host has 3 parts or more, as per Firefox's

		// ruleset.

		if (ip2long($host) === false) {

			$parts    = explode('.', $host);

			$parts[0] = '*';

			$wildcard = implode('.', $parts);

			if ($wildcard === $reference) {

				return true;

			}

		}

		return false;

	}

}