--- /dev/null
+<?php
+/**
+ * Session API: WP_Session_Tokens class
+ *
+ * @package WordPress
+ * @subpackage Session
+ * @since 4.7.0
+ */
+
+/**
+ * Abstract class for managing user session tokens.
+ *
+ * @since 4.0.0
+ */
+abstract class WP_Session_Tokens {
+
+ /**
+ * User ID.
+ *
+ * @since 4.0.0
+ * @access protected
+ * @var int User ID.
+ */
+ protected $user_id;
+
+ /**
+ * Protected constructor.
+ *
+ * @since 4.0.0
+ *
+ * @param int $user_id User whose session to manage.
+ */
+ protected function __construct( $user_id ) {
+ $this->user_id = $user_id;
+ }
+
+ /**
+ * Get a session token manager instance for a user.
+ *
+ * This method contains a filter that allows a plugin to swap out
+ * the session manager for a subclass of WP_Session_Tokens.
+ *
+ * @since 4.0.0
+ * @access public
+ * @static
+ *
+ * @param int $user_id User whose session to manage.
+ */
+ final public static function get_instance( $user_id ) {
+ /**
+ * Filters the session token manager used.
+ *
+ * @since 4.0.0
+ *
+ * @param string $session Name of class to use as the manager.
+ * Default 'WP_User_Meta_Session_Tokens'.
+ */
+ $manager = apply_filters( 'session_token_manager', 'WP_User_Meta_Session_Tokens' );
+ return new $manager( $user_id );
+ }
+
+ /**
+ * Hashes a session token for storage.
+ *
+ * @since 4.0.0
+ * @access private
+ *
+ * @param string $token Session token to hash.
+ * @return string A hash of the session token (a verifier).
+ */
+ final private function hash_token( $token ) {
+ // If ext/hash is not present, use sha1() instead.
+ if ( function_exists( 'hash' ) ) {
+ return hash( 'sha256', $token );
+ } else {
+ return sha1( $token );
+ }
+ }
+
+ /**
+ * Get a user's session.
+ *
+ * @since 4.0.0
+ * @access public
+ *
+ * @param string $token Session token
+ * @return array User session
+ */
+ final public function get( $token ) {
+ $verifier = $this->hash_token( $token );
+ return $this->get_session( $verifier );
+ }
+
+ /**
+ * Validate a user's session token as authentic.
+ *
+ * Checks that the given token is present and hasn't expired.
+ *
+ * @since 4.0.0
+ * @access public
+ *
+ * @param string $token Token to verify.
+ * @return bool Whether the token is valid for the user.
+ */
+ final public function verify( $token ) {
+ $verifier = $this->hash_token( $token );
+ return (bool) $this->get_session( $verifier );
+ }
+
+ /**
+ * Generate a session token and attach session information to it.
+ *
+ * A session token is a long, random string. It is used in a cookie
+ * link that cookie to an expiration time and to ensure the cookie
+ * becomes invalidated upon logout.
+ *
+ * This function generates a token and stores it with the associated
+ * expiration time (and potentially other session information via the
+ * {@see 'attach_session_information'} filter).
+ *
+ * @since 4.0.0
+ * @access public
+ *
+ * @param int $expiration Session expiration timestamp.
+ * @return string Session token.
+ */
+ final public function create( $expiration ) {
+ /**
+ * Filters the information attached to the newly created session.
+ *
+ * Could be used in the future to attach information such as
+ * IP address or user agent to a session.
+ *
+ * @since 4.0.0
+ *
+ * @param array $session Array of extra data.
+ * @param int $user_id User ID.
+ */
+ $session = apply_filters( 'attach_session_information', array(), $this->user_id );
+ $session['expiration'] = $expiration;
+
+ // IP address.
+ if ( !empty( $_SERVER['REMOTE_ADDR'] ) ) {
+ $session['ip'] = $_SERVER['REMOTE_ADDR'];
+ }
+
+ // User-agent.
+ if ( ! empty( $_SERVER['HTTP_USER_AGENT'] ) ) {
+ $session['ua'] = wp_unslash( $_SERVER['HTTP_USER_AGENT'] );
+ }
+
+ // Timestamp
+ $session['login'] = time();
+
+ $token = wp_generate_password( 43, false, false );
+
+ $this->update( $token, $session );
+
+ return $token;
+ }
+
+ /**
+ * Update a session token.
+ *
+ * @since 4.0.0
+ * @access public
+ *
+ * @param string $token Session token to update.
+ * @param array $session Session information.
+ */
+ final public function update( $token, $session ) {
+ $verifier = $this->hash_token( $token );
+ $this->update_session( $verifier, $session );
+ }
+
+ /**
+ * Destroy a session token.
+ *
+ * @since 4.0.0
+ * @access public
+ *
+ * @param string $token Session token to destroy.
+ */
+ final public function destroy( $token ) {
+ $verifier = $this->hash_token( $token );
+ $this->update_session( $verifier, null );
+ }
+
+ /**
+ * Destroy all session tokens for this user,
+ * except a single token, presumably the one in use.
+ *
+ * @since 4.0.0
+ * @access public
+ *
+ * @param string $token_to_keep Session token to keep.
+ */
+ final public function destroy_others( $token_to_keep ) {
+ $verifier = $this->hash_token( $token_to_keep );
+ $session = $this->get_session( $verifier );
+ if ( $session ) {
+ $this->destroy_other_sessions( $verifier );
+ } else {
+ $this->destroy_all_sessions();
+ }
+ }
+
+ /**
+ * Determine whether a session token is still valid,
+ * based on expiration.
+ *
+ * @since 4.0.0
+ * @access protected
+ *
+ * @param array $session Session to check.
+ * @return bool Whether session is valid.
+ */
+ final protected function is_still_valid( $session ) {
+ return $session['expiration'] >= time();
+ }
+
+ /**
+ * Destroy all session tokens for a user.
+ *
+ * @since 4.0.0
+ * @access public
+ */
+ final public function destroy_all() {
+ $this->destroy_all_sessions();
+ }
+
+ /**
+ * Destroy all session tokens for all users.
+ *
+ * @since 4.0.0
+ * @access public
+ * @static
+ */
+ final public static function destroy_all_for_all_users() {
+ $manager = apply_filters( 'session_token_manager', 'WP_User_Meta_Session_Tokens' );
+ call_user_func( array( $manager, 'drop_sessions' ) );
+ }
+
+ /**
+ * Retrieve all sessions of a user.
+ *
+ * @since 4.0.0
+ * @access public
+ *
+ * @return array Sessions of a user.
+ */
+ final public function get_all() {
+ return array_values( $this->get_sessions() );
+ }
+
+ /**
+ * This method should retrieve all sessions of a user, keyed by verifier.
+ *
+ * @since 4.0.0
+ * @access protected
+ *
+ * @return array Sessions of a user, keyed by verifier.
+ */
+ abstract protected function get_sessions();
+
+ /**
+ * This method should look up a session by its verifier (token hash).
+ *
+ * @since 4.0.0
+ * @access protected
+ *
+ * @param string $verifier Verifier of the session to retrieve.
+ * @return array|null The session, or null if it does not exist.
+ */
+ abstract protected function get_session( $verifier );
+
+ /**
+ * This method should update a session by its verifier.
+ *
+ * Omitting the second argument should destroy the session.
+ *
+ * @since 4.0.0
+ * @access protected
+ *
+ * @param string $verifier Verifier of the session to update.
+ * @param array $session Optional. Session. Omitting this argument destroys the session.
+ */
+ abstract protected function update_session( $verifier, $session = null );
+
+ /**
+ * This method should destroy all session tokens for this user,
+ * except a single session passed.
+ *
+ * @since 4.0.0
+ * @access protected
+ *
+ * @param string $verifier Verifier of the session to keep.
+ */
+ abstract protected function destroy_other_sessions( $verifier );
+
+ /**
+ * This method should destroy all sessions for a user.
+ *
+ * @since 4.0.0
+ * @access protected
+ */
+ abstract protected function destroy_all_sessions();
+
+ /**
+ * This static method should destroy all session tokens for all users.
+ *
+ * @since 4.0.0
+ * @access public
+ * @static
+ */
+ public static function drop_sessions() {}
+}