<?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;
}
}
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