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   1  <?php
   2  /**
   3   * HTTPS detection functions.
   4   *
   5   * @package WordPress
   6   * @since 5.7.0
   7   */
   8  
   9  /**
  10   * Checks whether the website is using HTTPS.
  11   *
  12   * This is based on whether both the home and site URL are using HTTPS.
  13   *
  14   * @since 5.7.0
  15   * @see wp_is_home_url_using_https()
  16   * @see wp_is_site_url_using_https()
  17   *
  18   * @return bool True if using HTTPS, false otherwise.
  19   */
  20  function wp_is_using_https() {
  21      if ( ! wp_is_home_url_using_https() ) {
  22          return false;
  23      }
  24  
  25      return wp_is_site_url_using_https();
  26  }
  27  
  28  /**
  29   * Checks whether the current site URL is using HTTPS.
  30   *
  31   * @since 5.7.0
  32   * @see home_url()
  33   *
  34   * @return bool True if using HTTPS, false otherwise.
  35   */
  36  function wp_is_home_url_using_https() {
  37      return 'https' === wp_parse_url( home_url(), PHP_URL_SCHEME );
  38  }
  39  
  40  /**
  41   * Checks whether the current site's URL where WordPress is stored is using HTTPS.
  42   *
  43   * This checks the URL where WordPress application files (e.g. wp-blog-header.php or the wp-admin/ folder)
  44   * are accessible.
  45   *
  46   * @since 5.7.0
  47   * @see site_url()
  48   *
  49   * @return bool True if using HTTPS, false otherwise.
  50   */
  51  function wp_is_site_url_using_https() {
  52      // Use direct option access for 'siteurl' and manually run the 'site_url'
  53      // filter because `site_url()` will adjust the scheme based on what the
  54      // current request is using.
  55      /** This filter is documented in wp-includes/link-template.php */
  56      $site_url = apply_filters( 'site_url', get_option( 'siteurl' ), '', null, null );
  57  
  58      return 'https' === wp_parse_url( $site_url, PHP_URL_SCHEME );
  59  }
  60  
  61  /**
  62   * Checks whether HTTPS is supported for the server and domain.
  63   *
  64   * @since 5.7.0
  65   *
  66   * @return bool True if HTTPS is supported, false otherwise.
  67   */
  68  function wp_is_https_supported() {
  69      $https_detection_errors = get_option( 'https_detection_errors' );
  70  
  71      // If option has never been set by the Cron hook before, run it on-the-fly as fallback.
  72      if ( false === $https_detection_errors ) {
  73          wp_update_https_detection_errors();
  74  
  75          $https_detection_errors = get_option( 'https_detection_errors' );
  76      }
  77  
  78      // If there are no detection errors, HTTPS is supported.
  79      return empty( $https_detection_errors );
  80  }
  81  
  82  /**
  83   * Runs a remote HTTPS request to detect whether HTTPS supported, and stores potential errors.
  84   *
  85   * This internal function is called by a regular Cron hook to ensure HTTPS support is detected and maintained.
  86   *
  87   * @since 5.7.0
  88   * @access private
  89   */
  90  function wp_update_https_detection_errors() {
  91      /**
  92       * Short-circuits the process of detecting errors related to HTTPS support.
  93       *
  94       * Returning a `WP_Error` from the filter will effectively short-circuit the default logic of trying a remote
  95       * request to the site over HTTPS, storing the errors array from the returned `WP_Error` instead.
  96       *
  97       * @since 5.7.0
  98       *
  99       * @param null|WP_Error $pre Error object to short-circuit detection,
 100       *                           or null to continue with the default behavior.
 101       */
 102      $support_errors = apply_filters( 'pre_wp_update_https_detection_errors', null );
 103      if ( is_wp_error( $support_errors ) ) {
 104          update_option( 'https_detection_errors', $support_errors->errors );
 105          return;
 106      }
 107  
 108      $support_errors = new WP_Error();
 109  
 110      $response = wp_remote_request(
 111          home_url( '/', 'https' ),
 112          array(
 113              'headers'   => array(
 114                  'Cache-Control' => 'no-cache',
 115              ),
 116              'sslverify' => true,
 117          )
 118      );
 119  
 120      if ( is_wp_error( $response ) ) {
 121          $unverified_response = wp_remote_request(
 122              home_url( '/', 'https' ),
 123              array(
 124                  'headers'   => array(
 125                      'Cache-Control' => 'no-cache',
 126                  ),
 127                  'sslverify' => false,
 128              )
 129          );
 130  
 131          if ( is_wp_error( $unverified_response ) ) {
 132              $support_errors->add(
 133                  'https_request_failed',
 134                  __( 'HTTPS request failed.' )
 135              );
 136          } else {
 137              $support_errors->add(
 138                  'ssl_verification_failed',
 139                  __( 'SSL verification failed.' )
 140              );
 141          }
 142  
 143          $response = $unverified_response;
 144      }
 145  
 146      if ( ! is_wp_error( $response ) ) {
 147          if ( 200 !== wp_remote_retrieve_response_code( $response ) ) {
 148              $support_errors->add( 'bad_response_code', wp_remote_retrieve_response_message( $response ) );
 149          } elseif ( false === wp_is_local_html_output( wp_remote_retrieve_body( $response ) ) ) {
 150              $support_errors->add( 'bad_response_source', __( 'It looks like the response did not come from this site.' ) );
 151          }
 152      }
 153  
 154      update_option( 'https_detection_errors', $support_errors->errors );
 155  }
 156  
 157  /**
 158   * Schedules the Cron hook for detecting HTTPS support.
 159   *
 160   * @since 5.7.0
 161   * @access private
 162   */
 163  function wp_schedule_https_detection() {
 164      if ( wp_installing() ) {
 165          return;
 166      }
 167  
 168      if ( ! wp_next_scheduled( 'wp_https_detection' ) ) {
 169          wp_schedule_event( time(), 'twicedaily', 'wp_https_detection' );
 170      }
 171  }
 172  
 173  /**
 174   * Disables SSL verification if the 'cron_request' arguments include an HTTPS URL.
 175   *
 176   * This prevents an issue if HTTPS breaks, where there would be a failed attempt to verify HTTPS.
 177   *
 178   * @since 5.7.0
 179   * @access private
 180   *
 181   * @param array $request The Cron request arguments.
 182   * @return array The filtered Cron request arguments.
 183   */
 184  function wp_cron_conditionally_prevent_sslverify( $request ) {
 185      if ( 'https' === wp_parse_url( $request['url'], PHP_URL_SCHEME ) ) {
 186          $request['args']['sslverify'] = false;
 187      }
 188      return $request;
 189  }
 190  
 191  /**
 192   * Checks whether a given HTML string is likely an output from this WordPress site.
 193   *
 194   * This function attempts to check for various common WordPress patterns whether they are included in the HTML string.
 195   * Since any of these actions may be disabled through third-party code, this function may also return null to indicate
 196   * that it was not possible to determine ownership.
 197   *
 198   * @since 5.7.0
 199   * @access private
 200   *
 201   * @param string $html Full HTML output string, e.g. from a HTTP response.
 202   * @return bool|null True/false for whether HTML was generated by this site, null if unable to determine.
 203   */
 204  function wp_is_local_html_output( $html ) {
 205      // 1. Check if HTML includes the site's Really Simple Discovery link.
 206      if ( has_action( 'wp_head', 'rsd_link' ) ) {
 207          $pattern = preg_replace( '#^https?:(?=//)#', '', esc_url( site_url( 'xmlrpc.php?rsd', 'rpc' ) ) ); // See rsd_link().
 208          return false !== strpos( $html, $pattern );
 209      }
 210  
 211      // 2. Check if HTML includes the site's Windows Live Writer manifest link.
 212      if ( has_action( 'wp_head', 'wlwmanifest_link' ) ) {
 213          // Try both HTTPS and HTTP since the URL depends on context.
 214          $pattern = preg_replace( '#^https?:(?=//)#', '', includes_url( 'wlwmanifest.xml' ) ); // See wlwmanifest_link().
 215          return false !== strpos( $html, $pattern );
 216      }
 217  
 218      // 3. Check if HTML includes the site's REST API link.
 219      if ( has_action( 'wp_head', 'rest_output_link_wp_head' ) ) {
 220          // Try both HTTPS and HTTP since the URL depends on context.
 221          $pattern = preg_replace( '#^https?:(?=//)#', '', esc_url( get_rest_url() ) ); // See rest_output_link_wp_head().
 222          return false !== strpos( $html, $pattern );
 223      }
 224  
 225      // Otherwise the result cannot be determined.
 226      return null;
 227  }