1<?php
  2/**
  3 * SSL utilities for Requests
  4 *
  5 * @package Requests\Utilities
  6 */
  7
  8namespace WpOrg\Requests;
  9
 10use WpOrg\Requests\Exception\InvalidArgument;
 11use WpOrg\Requests\Utility\InputValidator;
 12
 13/**
 14 * SSL utilities for Requests
 15 *
 16 * Collection of utilities for working with and verifying SSL certificates.
 17 *
 18 * @package Requests\Utilities
 19 */
 20final class Ssl {
 21	/**
 22	 * Verify the certificate against common name and subject alternative names
 23	 *
 24	 * Unfortunately, PHP doesn't check the certificate against the alternative
 25	 * names, leading things like 'https://www.github.com/' to be invalid.
 26	 *
 27	 * @link https://tools.ietf.org/html/rfc2818#section-3.1 RFC2818, Section 3.1
 28	 *
 29	 * @param string|Stringable $host Host name to verify against
 30	 * @param array $cert Certificate data from openssl_x509_parse()
 31	 * @return bool
 32	 * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed $host argument is not a string or a stringable object.
 33	 * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed $cert argument is not an array or array accessible.
 34	 */
 35	public static function verify_certificate($host, $cert) {
 36		if (InputValidator::is_string_or_stringable($host) === false) {
 37			throw InvalidArgument::create(1, '$host', 'string|Stringable', gettype($host));
 38		}
 39
 40		if (InputValidator::has_array_access($cert) === false) {
 41			throw InvalidArgument::create(2, '$cert', 'array|ArrayAccess', gettype($cert));
 42		}
 43
 44		$has_dns_alt = false;
 45
 46		// Check the subjectAltName
 47		if (!empty($cert['extensions']['subjectAltName'])) {
 48			$altnames = explode(',', $cert['extensions']['subjectAltName']);
 49			foreach ($altnames as $altname) {
 50				$altname = trim($altname);
 51				if (strpos($altname, 'DNS:') !== 0) {
 52					continue;
 53				}
 54
 55				$has_dns_alt = true;
 56
 57				// Strip the 'DNS:' prefix and trim whitespace
 58				$altname = trim(substr($altname, 4));
 59
 60				// Check for a match
 61				if (self::match_domain($host, $altname) === true) {
 62					return true;
 63				}
 64			}
 65
 66			if ($has_dns_alt === true) {
 67				return false;
 68			}
 69		}
 70
 71		// Fall back to checking the common name if we didn't get any dNSName
 72		// alt names, as per RFC2818
 73		if (!empty($cert['subject']['CN'])) {
 74			// Check for a match
 75			return (self::match_domain($host, $cert['subject']['CN']) === true);
 76		}
 77
 78		return false;
 79	}
 80
 81	/**
 82	 * Verify that a reference name is valid
 83	 *
 84	 * Verifies a dNSName for HTTPS usage, (almost) as per Firefox's rules:
 85	 * - Wildcards can only occur in a name with more than 3 components
 86	 * - Wildcards can only occur as the last character in the first
 87	 *   component
 88	 * - Wildcards may be preceded by additional characters
 89	 *
 90	 * We modify these rules to be a bit stricter and only allow the wildcard
 91	 * character to be the full first component; that is, with the exclusion of
 92	 * the third rule.
 93	 *
 94	 * @param string|Stringable $reference Reference dNSName
 95	 * @return boolean Is the name valid?
 96	 * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed argument is not a string or a stringable object.
 97	 */
 98	public static function verify_reference_name($reference) {
 99		if (InputValidator::is_string_or_stringable($reference) === false) {
100			throw InvalidArgument::create(1, '$reference', 'string|Stringable', gettype($reference));
101		}
102
103		if ($reference === '') {
104			return false;
105		}
106
107		if (preg_match('`\s`', $reference) > 0) {
108			// Whitespace detected. This can never be a dNSName.
109			return false;
110		}
111
112		$parts = explode('.', $reference);
113		if ($parts !== array_filter($parts)) {
114			// DNSName cannot contain two dots next to each other.
115			return false;
116		}
117
118		// Check the first part of the name
119		$first = array_shift($parts);
120
121		if (strpos($first, '*') !== false) {
122			// Check that the wildcard is the full part
123			if ($first !== '*') {
124				return false;
125			}
126
127			// Check that we have at least 3 components (including first)
128			if (count($parts) < 2) {
129				return false;
130			}
131		}
132
133		// Check the remaining parts
134		foreach ($parts as $part) {
135			if (strpos($part, '*') !== false) {
136				return false;
137			}
138		}
139
140		// Nothing found, verified!
141		return true;
142	}
143
144	/**
145	 * Match a hostname against a dNSName reference
146	 *
147	 * @param string|Stringable $host Requested host
148	 * @param string|Stringable $reference dNSName to match against
149	 * @return boolean Does the domain match?
150	 * @throws \WpOrg\Requests\Exception\InvalidArgument When either of the passed arguments is not a string or a stringable object.
151	 */
152	public static function match_domain($host, $reference) {
153		if (InputValidator::is_string_or_stringable($host) === false) {
154			throw InvalidArgument::create(1, '$host', 'string|Stringable', gettype($host));
155		}
156
157		// Check if the reference is blocklisted first
158		if (self::verify_reference_name($reference) !== true) {
159			return false;
160		}
161
162		// Check for a direct match
163		if ((string) $host === (string) $reference) {
164			return true;
165		}
166
167		// Calculate the valid wildcard match if the host is not an IP address
168		// Also validates that the host has 3 parts or more, as per Firefox's ruleset,
169		// as a wildcard reference is only allowed with 3 parts or more, so the
170		// comparison will never match if host doesn't contain 3 parts or more as well.
171		if (ip2long($host) === false) {
172			$parts    = explode('.', $host);
173			$parts[0] = '*';
174			$wildcard = implode('.', $parts);
175			if ($wildcard === (string) $reference) {
176				return true;
177			}
178		}
179
180		return false;
181	}
182}
183