+
+/**
+ * Get the HTTP Origin of the current request.
+ *
+ * @since 3.4.0
+ *
+ * @return string URL of the origin. Empty string if no origin.
+ */
+function get_http_origin() {
+ $origin = '';
+ if ( ! empty ( $_SERVER[ 'HTTP_ORIGIN' ] ) )
+ $origin = $_SERVER[ 'HTTP_ORIGIN' ];
+
+ /**
+ * Change the origin of an HTTP request.
+ *
+ * @since 3.4.0
+ *
+ * @param string $origin The original origin for the request.
+ */
+ return apply_filters( 'http_origin', $origin );
+}
+
+/**
+ * Retrieve list of allowed HTTP origins.
+ *
+ * @since 3.4.0
+ *
+ * @return array Array of origin URLs.
+ */
+function get_allowed_http_origins() {
+ $admin_origin = parse_url( admin_url() );
+ $home_origin = parse_url( home_url() );
+
+ // @todo preserve port?
+ $allowed_origins = array_unique( array(
+ 'http://' . $admin_origin[ 'host' ],
+ 'https://' . $admin_origin[ 'host' ],
+ 'http://' . $home_origin[ 'host' ],
+ 'https://' . $home_origin[ 'host' ],
+ ) );
+
+ /**
+ * Change the origin types allowed for HTTP requests.
+ *
+ * @since 3.4.0
+ *
+ * @param array $allowed_origins {
+ * Default allowed HTTP origins.
+ * @type string Non-secure URL for admin origin.
+ * @type string Secure URL for admin origin.
+ * @type string Non-secure URL for home origin.
+ * @type string Secure URL for home origin.
+ * }
+ */
+ return apply_filters( 'allowed_http_origins' , $allowed_origins );
+}
+
+/**
+ * Determines if the HTTP origin is an authorized one.
+ *
+ * @since 3.4.0
+ *
+ * @param string Origin URL. If not provided, the value of get_http_origin() is used.
+ * @return bool True if the origin is allowed. False otherwise.
+ */
+function is_allowed_http_origin( $origin = null ) {
+ $origin_arg = $origin;
+
+ if ( null === $origin )
+ $origin = get_http_origin();
+
+ if ( $origin && ! in_array( $origin, get_allowed_http_origins() ) )
+ $origin = '';
+
+ /**
+ * Change the allowed HTTP origin result.
+ *
+ * @since 3.4.0
+ *
+ * @param string $origin Result of check for allowed origin.
+ * @param string $origin_arg original origin string passed into is_allowed_http_origin function.
+ */
+ return apply_filters( 'allowed_http_origin', $origin, $origin_arg );
+}
+
+/**
+ * Send Access-Control-Allow-Origin and related headers if the current request
+ * is from an allowed origin.
+ *
+ * If the request is an OPTIONS request, the script exits with either access
+ * control headers sent, or a 403 response if the origin is not allowed. For
+ * other request methods, you will receive a return value.
+ *
+ * @since 3.4.0
+ *
+ * @return bool|string Returns the origin URL if headers are sent. Returns false
+ * if headers are not sent.
+ */
+function send_origin_headers() {
+ $origin = get_http_origin();
+
+ if ( is_allowed_http_origin( $origin ) ) {
+ @header( 'Access-Control-Allow-Origin: ' . $origin );
+ @header( 'Access-Control-Allow-Credentials: true' );
+ if ( 'OPTIONS' === $_SERVER['REQUEST_METHOD'] )
+ exit;
+ return $origin;
+ }
+
+ if ( 'OPTIONS' === $_SERVER['REQUEST_METHOD'] ) {
+ status_header( 403 );
+ exit;
+ }
+
+ return false;
+}
+
+/**
+ * Validate a URL for safe use in the HTTP API.
+ *
+ * @since 3.5.2
+ *
+ * @return mixed URL or false on failure.
+ */
+function wp_http_validate_url( $url ) {
+ $url = wp_kses_bad_protocol( $url, array( 'http', 'https' ) );
+ if ( ! $url )
+ return false;
+
+ $parsed_url = @parse_url( $url );
+ if ( ! $parsed_url || empty( $parsed_url['host'] ) )
+ return false;
+
+ if ( isset( $parsed_url['user'] ) || isset( $parsed_url['pass'] ) )
+ return false;
+
+ if ( false !== strpos( $parsed_url['host'], ':' ) )
+ return false;
+
+ $parsed_home = @parse_url( get_option( 'home' ) );
+
+ $same_host = strtolower( $parsed_home['host'] ) === strtolower( $parsed_url['host'] );
+
+ if ( ! $same_host ) {
+ $host = trim( $parsed_url['host'], '.' );
+ if ( preg_match( '#^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}$#', $host ) ) {
+ $ip = $host;
+ } else {
+ $ip = gethostbyname( $host );
+ if ( $ip === $host ) // Error condition for gethostbyname()
+ $ip = false;
+ }
+ if ( $ip ) {
+ $parts = array_map( 'intval', explode( '.', $ip ) );
+ if ( '127.0.0.1' === $ip
+ || ( 10 === $parts[0] )
+ || ( 172 === $parts[0] && 16 <= $parts[1] && 31 >= $parts[1] )
+ || ( 192 === $parts[0] && 168 === $parts[1] )
+ ) {
+ // If host appears local, reject unless specifically allowed.
+ /**
+ * Check if HTTP request is external or not.
+ *
+ * Allows to change and allow external requests for the HTTP request.
+ *
+ * @since 3.6.0
+ *
+ * @param bool false Whether HTTP request is external or not.
+ * @param string $host IP of the requested host.
+ * @param string $url URL of the requested host.
+ */
+ if ( ! apply_filters( 'http_request_host_is_external', false, $host, $url ) )
+ return false;
+ }
+ }
+ }
+
+ if ( empty( $parsed_url['port'] ) )
+ return $url;
+
+ $port = $parsed_url['port'];
+ if ( 80 === $port || 443 === $port || 8080 === $port )
+ return $url;
+
+ if ( $parsed_home && $same_host && $parsed_home['port'] === $port )
+ return $url;
+
+ return false;
+}
+
+/**
+ * Whitelists allowed redirect hosts for safe HTTP requests as well.
+ *
+ * Attached to the http_request_host_is_external filter.
+ *
+ * @since 3.6.0
+ *
+ * @param bool $is_external
+ * @param string $host
+ * @return bool
+ */
+function allowed_http_request_hosts( $is_external, $host ) {
+ if ( ! $is_external && wp_validate_redirect( 'http://' . $host ) )
+ $is_external = true;
+ return $is_external;
+}
+
+/**
+ * Whitelists any domain in a multisite installation for safe HTTP requests.
+ *
+ * Attached to the http_request_host_is_external filter.
+ *
+ * @since 3.6.0
+ *
+ * @param bool $is_external
+ * @param string $host
+ * @return bool
+ */
+function ms_allowed_http_request_hosts( $is_external, $host ) {
+ global $wpdb, $current_site;
+ static $queried = array();
+ if ( $is_external )
+ return $is_external;
+ if ( $host === $current_site->domain )
+ return true;
+ if ( isset( $queried[ $host ] ) )
+ return $queried[ $host ];
+ $queried[ $host ] = (bool) $wpdb->get_var( $wpdb->prepare( "SELECT domain FROM $wpdb->blogs WHERE domain = %s LIMIT 1", $host ) );
+ return $queried[ $host ];
+}