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   1  <?php
   2  /**
   3   * Error Protection API: WP_Recovery_Mode_Cookie_Service class
   4   *
   5   * @package WordPress
   6   * @since 5.2.0
   7   */
   8  
   9  /**
  10   * Core class used to set, validate, and clear cookies that identify a Recovery Mode session.
  11   *
  12   * @since 5.2.0
  13   */
  14  final class WP_Recovery_Mode_Cookie_Service {
  15  
  16      /**
  17       * Checks whether the recovery mode cookie is set.
  18       *
  19       * @since 5.2.0
  20       *
  21       * @return bool True if the cookie is set, false otherwise.
  22       */
  23  	public function is_cookie_set() {
  24          return ! empty( $_COOKIE[ RECOVERY_MODE_COOKIE ] );
  25      }
  26  
  27      /**
  28       * Sets the recovery mode cookie.
  29       *
  30       * This must be immediately followed by exiting the request.
  31       *
  32       * @since 5.2.0
  33       */
  34  	public function set_cookie() {
  35  
  36          $value = $this->generate_cookie();
  37  
  38          /**
  39           * Filters the length of time a Recovery Mode cookie is valid for.
  40           *
  41           * @since 5.2.0
  42           *
  43           * @param int $length Length in seconds.
  44           */
  45          $length = apply_filters( 'recovery_mode_cookie_length', WEEK_IN_SECONDS );
  46  
  47          $expire = time() + $length;
  48  
  49          setcookie( RECOVERY_MODE_COOKIE, $value, $expire, COOKIEPATH, COOKIE_DOMAIN, is_ssl(), true );
  50  
  51          if ( COOKIEPATH !== SITECOOKIEPATH ) {
  52              setcookie( RECOVERY_MODE_COOKIE, $value, $expire, SITECOOKIEPATH, COOKIE_DOMAIN, is_ssl(), true );
  53          }
  54      }
  55  
  56      /**
  57       * Clears the recovery mode cookie.
  58       *
  59       * @since 5.2.0
  60       */
  61  	public function clear_cookie() {
  62          setcookie( RECOVERY_MODE_COOKIE, ' ', time() - YEAR_IN_SECONDS, COOKIEPATH, COOKIE_DOMAIN );
  63          setcookie( RECOVERY_MODE_COOKIE, ' ', time() - YEAR_IN_SECONDS, SITECOOKIEPATH, COOKIE_DOMAIN );
  64      }
  65  
  66      /**
  67       * Validates the recovery mode cookie.
  68       *
  69       * @since 5.2.0
  70       *
  71       * @param string $cookie Optionally specify the cookie string.
  72       *                       If omitted, it will be retrieved from the super global.
  73       * @return true|WP_Error True on success, error object on failure.
  74       */
  75  	public function validate_cookie( $cookie = '' ) {
  76  
  77          if ( ! $cookie ) {
  78              if ( empty( $_COOKIE[ RECOVERY_MODE_COOKIE ] ) ) {
  79                  return new WP_Error( 'no_cookie', __( 'No cookie present.' ) );
  80              }
  81  
  82              $cookie = $_COOKIE[ RECOVERY_MODE_COOKIE ];
  83          }
  84  
  85          $parts = $this->parse_cookie( $cookie );
  86  
  87          if ( is_wp_error( $parts ) ) {
  88              return $parts;
  89          }
  90  
  91          list( , $created_at, $random, $signature ) = $parts;
  92  
  93          if ( ! ctype_digit( $created_at ) ) {
  94              return new WP_Error( 'invalid_created_at', __( 'Invalid cookie format.' ) );
  95          }
  96  
  97          /** This filter is documented in wp-includes/class-wp-recovery-mode-cookie-service.php */
  98          $length = apply_filters( 'recovery_mode_cookie_length', WEEK_IN_SECONDS );
  99  
 100          if ( time() > $created_at + $length ) {
 101              return new WP_Error( 'expired', __( 'Cookie expired.' ) );
 102          }
 103  
 104          $to_sign = sprintf( 'recovery_mode|%s|%s', $created_at, $random );
 105          $hashed  = $this->recovery_mode_hash( $to_sign );
 106  
 107          if ( ! hash_equals( $signature, $hashed ) ) {
 108              return new WP_Error( 'signature_mismatch', __( 'Invalid cookie.' ) );
 109          }
 110  
 111          return true;
 112      }
 113  
 114      /**
 115       * Gets the session identifier from the cookie.
 116       *
 117       * The cookie should be validated before calling this API.
 118       *
 119       * @since 5.2.0
 120       *
 121       * @param string $cookie Optionally specify the cookie string.
 122       *                       If omitted, it will be retrieved from the super global.
 123       * @return string|WP_Error Session ID on success, or error object on failure.
 124       */
 125  	public function get_session_id_from_cookie( $cookie = '' ) {
 126          if ( ! $cookie ) {
 127              if ( empty( $_COOKIE[ RECOVERY_MODE_COOKIE ] ) ) {
 128                  return new WP_Error( 'no_cookie', __( 'No cookie present.' ) );
 129              }
 130  
 131              $cookie = $_COOKIE[ RECOVERY_MODE_COOKIE ];
 132          }
 133  
 134          $parts = $this->parse_cookie( $cookie );
 135          if ( is_wp_error( $parts ) ) {
 136              return $parts;
 137          }
 138  
 139          list( , , $random ) = $parts;
 140  
 141          return sha1( $random );
 142      }
 143  
 144      /**
 145       * Parses the cookie into its four parts.
 146       *
 147       * @since 5.2.0
 148       *
 149       * @param string $cookie Cookie content.
 150       * @return array|WP_Error Cookie parts array, or error object on failure.
 151       */
 152  	private function parse_cookie( $cookie ) {
 153          $cookie = base64_decode( $cookie );
 154          $parts  = explode( '|', $cookie );
 155  
 156          if ( 4 !== count( $parts ) ) {
 157              return new WP_Error( 'invalid_format', __( 'Invalid cookie format.' ) );
 158          }
 159  
 160          return $parts;
 161      }
 162  
 163      /**
 164       * Generates the recovery mode cookie value.
 165       *
 166       * The cookie is a base64 encoded string with the following format:
 167       *
 168       * recovery_mode|iat|rand|signature
 169       *
 170       * Where "recovery_mode" is a constant string,
 171       * iat is the time the cookie was generated at,
 172       * rand is a randomly generated password that is also used as a session identifier
 173       * and signature is an hmac of the preceding 3 parts.
 174       *
 175       * @since 5.2.0
 176       *
 177       * @return string Generated cookie content.
 178       */
 179  	private function generate_cookie() {
 180          $to_sign = sprintf( 'recovery_mode|%s|%s', time(), wp_generate_password( 20, false ) );
 181          $signed  = $this->recovery_mode_hash( $to_sign );
 182  
 183          return base64_encode( sprintf( '%s|%s', $to_sign, $signed ) );
 184      }
 185  
 186      /**
 187       * Gets a form of `wp_hash()` specific to Recovery Mode.
 188       *
 189       * We cannot use `wp_hash()` because it is defined in `pluggable.php` which is not loaded until after plugins are loaded,
 190       * which is too late to verify the recovery mode cookie.
 191       *
 192       * This tries to use the `AUTH` salts first, but if they aren't valid specific salts will be generated and stored.
 193       *
 194       * @since 5.2.0
 195       *
 196       * @param string $data Data to hash.
 197       * @return string|false The hashed $data, or false on failure.
 198       */
 199  	private function recovery_mode_hash( $data ) {
 200          if ( ! defined( 'AUTH_KEY' ) || AUTH_KEY === 'put your unique phrase here' ) {
 201              $auth_key = get_site_option( 'recovery_mode_auth_key' );
 202  
 203              if ( ! $auth_key ) {
 204                  if ( ! function_exists( 'wp_generate_password' ) ) {
 205                      require_once  ABSPATH . WPINC . '/pluggable.php';
 206                  }
 207  
 208                  $auth_key = wp_generate_password( 64, true, true );
 209                  update_site_option( 'recovery_mode_auth_key', $auth_key );
 210              }
 211          } else {
 212              $auth_key = AUTH_KEY;
 213          }
 214  
 215          if ( ! defined( 'AUTH_SALT' ) || AUTH_SALT === 'put your unique phrase here' || AUTH_SALT === $auth_key ) {
 216              $auth_salt = get_site_option( 'recovery_mode_auth_salt' );
 217  
 218              if ( ! $auth_salt ) {
 219                  if ( ! function_exists( 'wp_generate_password' ) ) {
 220                      require_once  ABSPATH . WPINC . '/pluggable.php';
 221                  }
 222  
 223                  $auth_salt = wp_generate_password( 64, true, true );
 224                  update_site_option( 'recovery_mode_auth_salt', $auth_salt );
 225              }
 226          } else {
 227              $auth_salt = AUTH_SALT;
 228          }
 229  
 230          $secret = $auth_key . $auth_salt;
 231  
 232          return hash_hmac( 'sha1', $data, $secret );
 233      }
 234  }