' ), 'type' => 'string', 'context' => array( 'view', 'edit', 'embed' ), 'readonly' => true, ), 'icon' => array( 'description' => sprintf( /* translators: %s: HTML link tag. */ __( 'The favicon image link of the %s element from the URL.' ), '<link rel="icon">' ), 'type' => 'string', 'format' => 'uri', 'context' => array( 'view', 'edit', 'embed' ), 'readonly' => true, ), 'description' => array( 'description' => sprintf( /* translators: %s: HTML meta tag. */ __( 'The content of the %s element from the URL.' ), '<meta name="description">' ), 'type' => 'string', 'context' => array( 'view', 'edit', 'embed' ), 'readonly' => true, ), 'image' => array( 'description' => sprintf( /* translators: 1: HTML meta tag, 2: HTML meta tag. */ __( 'The Open Graph image link of the %1$s or %2$s element from the URL.' ), '<meta property="og:image">', '<meta property="og:image:url">' ), 'type' => 'string', 'format' => 'uri', 'context' => array( 'view', 'edit', 'embed' ), 'readonly' => true, ), ), ); return $this->add_additional_fields_schema( $this->schema ); } /** * Retrieves the contents of the title tag from the HTML response. * * @since 5.9.0 * * @param WP_REST_REQUEST $request Full details about the request. * @return WP_REST_Response|WP_Error The parsed details as a response object. WP_Error if there are errors. */ public function parse_url_details( $request ) { $url = untrailingslashit( $request['url'] ); if ( empty( $url ) ) { return new WP_Error( 'rest_invalid_url', __( 'Invalid URL' ), array( 'status' => 404 ) ); } // Transient per URL. $cache_key = $this->build_cache_key_for_url( $url ); // Attempt to retrieve cached response. $cached_response = $this->get_cache( $cache_key ); if ( ! empty( $cached_response ) ) { $remote_url_response = $cached_response; } else { $remote_url_response = $this->get_remote_url( $url ); // Exit if we don't have a valid body or it's empty. if ( is_wp_error( $remote_url_response ) || empty( $remote_url_response ) ) { return $remote_url_response; } // Cache the valid response. $this->set_cache( $cache_key, $remote_url_response ); } $html_head = $this->get_document_head( $remote_url_response ); $meta_elements = $this->get_meta_with_content_elements( $html_head ); $data = $this->add_additional_fields_to_object( array( 'title' => $this->get_title( $html_head ), 'icon' => $this->get_icon( $html_head, $url ), 'description' => $this->get_description( $meta_elements ), 'image' => $this->get_image( $meta_elements, $url ), ), $request ); // Wrap the data in a response object. $response = rest_ensure_response( $data ); /** * Filters the URL data for the response. * * @since 5.9.0 * * @param WP_REST_Response $response The response object. * @param string $url The requested URL. * @param WP_REST_Request $request Request object. * @param string $remote_url_response HTTP response body from the remote URL. */ return apply_filters( 'rest_prepare_url_details', $response, $url, $request, $remote_url_response ); } /** * Checks whether a given request has permission to read remote URLs. * * @since 5.9.0 * * @return WP_Error|bool True if the request has permission, else WP_Error. */ public function permissions_check() { if ( current_user_can( 'edit_posts' ) ) { return true; } foreach ( get_post_types( array( 'show_in_rest' => true ), 'objects' ) as $post_type ) { if ( current_user_can( $post_type->cap->edit_posts ) ) { return true; } } return new WP_Error( 'rest_cannot_view_url_details', __( 'Sorry, you are not allowed to process remote URLs.' ), array( 'status' => rest_authorization_required_code() ) ); } /** * Retrieves the document title from a remote URL. * * @since 5.9.0 * * @param string $url The website URL whose HTML to access. * @return string|WP_Error The HTTP response from the remote URL on success. * WP_Error if no response or no content. */ private function get_remote_url( $url ) { /* * Provide a modified UA string to workaround web properties which block WordPress "Pingbacks". * Why? The UA string used for pingback requests contains `WordPress/` which is very similar * to that used as the default UA string by the WP HTTP API. Therefore requests from this * REST endpoint are being unintentionally blocked as they are misidentified as pingback requests. * By slightly modifying the UA string, but still retaining the "WordPress" identification (via "WP") * we are able to work around this issue. * Example UA string: `WP-URLDetails/5.9-alpha-51389 (+http://localhost:8888)`. */ $modified_user_agent = 'WP-URLDetails/' . get_bloginfo( 'version' ) . ' (+' . get_bloginfo( 'url' ) . ')'; $args = array( 'limit_response_size' => 150 * KB_IN_BYTES, 'user-agent' => $modified_user_agent, ); /** * Filters the HTTP request args for URL data retrieval. * * Can be used to adjust response size limit and other WP_Http::request() args. * * @since 5.9.0 * * @param array $args Arguments used for the HTTP request. * @param string $url The attempted URL. */ $args = apply_filters( 'rest_url_details_http_request_args', $args, $url ); $response = wp_safe_remote_get( $url, $args ); if ( WP_Http::OK !== wp_remote_retrieve_response_code( $response ) ) { // Not saving the error response to cache since the error might be temporary. return new WP_Error( 'no_response', __( 'URL not found. Response returned a non-200 status code for this URL.' ), array( 'status' => WP_Http::NOT_FOUND ) ); } $remote_body = wp_remote_retrieve_body( $response ); if ( empty( $remote_body ) ) { return new WP_Error( 'no_content', __( 'Unable to retrieve body from response at this URL.' ), array( 'status' => WP_Http::NOT_FOUND ) ); } return $remote_body; } /** * Parses the title tag contents from the provided HTML. * * @since 5.9.0 * * @param string $html The HTML from the remote website at URL. * @return string The title tag contents on success. Empty string if not found. */ private function get_title( $html ) { $pattern = '#<title[^>]*>(.*?)<\s*/\s*title>#is'; preg_match( $pattern, $html, $match_title ); if ( empty( $match_title[1] ) || ! is_string( $match_title[1] ) ) { return ''; } $title = trim( $match_title[1] ); return $this->prepare_metadata_for_output( $title ); } /** * Parses the site icon from the provided HTML. * * @since 5.9.0 * * @param string $html The HTML from the remote website at URL. * @param string $url The target website URL. * @return string The icon URI on success. Empty string if not found. */ private function get_icon( $html, $url ) { // Grab the icon's link element. $pattern = '#<link\s[^>]*rel=(?:[\"\']??)\s*(?:icon|shortcut icon|icon shortcut)\s*(?:[\"\']??)[^>]*\/?>#isU'; preg_match( $pattern, $html, $element ); if ( empty( $element[0] ) || ! is_string( $element[0] ) ) { return ''; } $element = trim( $element[0] ); // Get the icon's href value. $pattern = '#href=([\"\']??)([^\" >]*?)\\1[^>]*#isU'; preg_match( $pattern, $element, $icon ); if ( empty( $icon[2] ) || ! is_string( $icon[2] ) ) { return ''; } $icon = trim( $icon[2] ); // If the icon is a data URL, return it. $parsed_icon = parse_url( $icon ); if ( isset( $parsed_icon['scheme'] ) && 'data' === $parsed_icon['scheme'] ) { return $icon; } // Attempt to convert relative URLs to absolute. if ( ! is_string( $url ) || '' === $url ) { return $icon; } $parsed_url = parse_url( $url ); if ( isset( $parsed_url['scheme'] ) && isset( $parsed_url['host'] ) ) { $root_url = $parsed_url['scheme'] . '://' . $parsed_url['host'] . '/'; $icon = WP_Http::make_absolute_url( $icon, $root_url ); } return $icon; } /** * Parses the meta description from the provided HTML. * * @since 5.9.0 * * @param array $meta_elements { * A multi-dimensional indexed array on success, else empty array. * * @type string[] $0 Meta elements with a content attribute. * @type string[] $1 Content attribute's opening quotation mark. * @type string[] $2 Content attribute's value for each meta element. * } * @return string The meta description contents on success. Empty string if not found. */ private function get_description( $meta_elements ) { // Bail out if there are no meta elements. if ( empty( $meta_elements[0] ) ) { return ''; } $description = $this->get_metadata_from_meta_element( $meta_elements, 'name', '(?:description|og:description)' ); // Bail out if description not found. if ( '' === $description ) { return ''; } return $this->prepare_metadata_for_output( $description ); } /** * Parses the Open Graph (OG) Image from the provided HTML. * * See: https://ogp.me/. * * @since 5.9.0 * * @param array $meta_elements { * A multi-dimensional indexed array on success, else empty array. * * @type string[] $0 Meta elements with a content attribute. * @type string[] $1 Content attribute's opening quotation mark. * @type string[] $2 Content attribute's value for each meta element. * } * @param string $url The target website URL. * @return string The OG image on success. Empty string if not found. */ private function get_image( $meta_elements, $url ) { $image = $this->get_metadata_from_meta_element( $meta_elements, 'property', '(?:og:image|og:image:url)' ); // Bail out if image not found. if ( '' === $image ) { return ''; } // Attempt to convert relative URLs to absolute. $parsed_url = parse_url( $url ); if ( isset( $parsed_url['scheme'] ) && isset( $parsed_url['host'] ) ) { $root_url = $parsed_url['scheme'] . '://' . $parsed_url['host'] . '/'; $image = WP_Http::make_absolute_url( $image, $root_url ); } return $image; } /** * Prepares the metadata by: * - stripping all HTML tags and tag entities. * - converting non-tag entities into characters. * * @since 5.9.0 * * @param string $metadata The metadata content to prepare. * @return string The prepared metadata. */ private function prepare_metadata_for_output( $metadata ) { $metadata = html_entity_decode( $metadata, ENT_QUOTES, get_bloginfo( 'charset' ) ); $metadata = wp_strip_all_tags( $metadata ); return $metadata; } /** * Utility function to build cache key for a given URL. * * @since 5.9.0 * * @param string $url The URL for which to build a cache key. * @return string The cache key. */ private function build_cache_key_for_url( $url ) { return 'g_url_details_response_' . md5( $url ); } /** * Utility function to retrieve a value from the cache at a given key. * * @since 5.9.0 * * @param string $key The cache key. * @return mixed The value from the cache. */ private function get_cache( $key ) { return get_site_transient( $key ); } /** * Utility function to cache a given data set at a given cache key. * * @since 5.9.0 * * @param string $key The cache key under which to store the value. * @param string $data The data to be stored at the given cache key. * @return bool True when transient set. False if not set. */ private function set_cache( $key, $data = '' ) { $ttl = HOUR_IN_SECONDS; /** * Filters the cache expiration. * * Can be used to adjust the time until expiration in seconds for the cache * of the data retrieved for the given URL. * * @since 5.9.0 * * @param int $ttl The time until cache expiration in seconds. */ $cache_expiration = apply_filters( 'rest_url_details_cache_expiration', $ttl ); return set_site_transient( $key, $data, $cache_expiration ); } /** * Retrieves the head element section. * * @since 5.9.0 * * @param string $html The string of HTML to parse. * @return string The `<head>..</head>` section on success. Given `$html` if not found. */ private function get_document_head( $html ) { $head_html = $html; // Find the opening `<head>` tag. $head_start = strpos( $html, '<head' ); if ( false === $head_start ) { // Didn't find it. Return the original HTML. return $html; } // Find the closing `</head>` tag. $head_end = strpos( $head_html, '</head>' ); if ( false === $head_end ) { // Didn't find it. Find the opening `<body>` tag. $head_end = strpos( $head_html, '<body' ); // Didn't find it. Return the original HTML. if ( false === $head_end ) { return $html; } } // Extract the HTML from opening tag to the closing tag. Then add the closing tag. $head_html = substr( $head_html, $head_start, $head_end ); $head_html .= '</head>'; return $head_html; } /** * Gets all the meta tag elements that have a 'content' attribute. * * @since 5.9.0 * * @param string $html The string of HTML to be parsed. * @return array { * A multi-dimensional indexed array on success, else empty array. * * @type string[] $0 Meta elements with a content attribute. * @type string[] $1 Content attribute's opening quotation mark. * @type string[] $2 Content attribute's value for each meta element. * } */ private function get_meta_with_content_elements( $html ) { /* * Parse all meta elements with a content attribute. * * Why first search for the content attribute rather than directly searching for name=description element? * tl;dr The content attribute's value will be truncated when it contains a > symbol. * * The content attribute's value (i.e. the description to get) can have HTML in it and be well-formed as * it's a string to the browser. Imagine what happens when attempting to match for the name=description * first. Hmm, if a > or /> symbol is in the content attribute's value, then it terminates the match * as the element's closing symbol. But wait, it's in the content attribute and is not the end of the * element. This is a limitation of using regex. It can't determine "wait a minute this is inside of quotation". * If this happens, what gets matched is not the entire element or all of the content. * * Why not search for the name=description and then content="(.*)"? * The attribute order could be opposite. Plus, additional attributes may exist including being between * the name and content attributes. * * Why not lookahead? * Lookahead is not constrained to stay within the element. The first <meta it finds may not include * the name or content, but rather could be from a different element downstream. */ $pattern = '#<meta\s' . /* * Allows for additional attributes before the content attribute. * Searches for anything other than > symbol. */ '[^>]*' . /* * Find the content attribute. When found, capture its value (.*). * * Allows for (a) single or double quotes and (b) whitespace in the value. * * Why capture the opening quotation mark, i.e. (["\']), and then backreference, * i.e \1, for the closing quotation mark? * To ensure the closing quotation mark matches the opening one. Why? Attribute values * can contain quotation marks, such as an apostrophe in the content. */ 'content=(["\']??)(.*)\1' . /* * Allows for additional attributes after the content attribute. * Searches for anything other than > symbol. */ '[^>]*' . /* * \/?> searches for the closing > symbol, which can be in either /> or > format. * # ends the pattern. */ '\/?>#' . /* * These are the options: * - i : case insensitive * - s : allows newline characters for the . match (needed for multiline elements) * - U means non-greedy matching */ 'isU'; preg_match_all( $pattern, $html, $elements ); return $elements; } /** * Gets the metadata from a target meta element. * * @since 5.9.0 * * @param array $meta_elements { * A multi-dimensional indexed array on success, else empty array. * * @type string[] $0 Meta elements with a content attribute. * @type string[] $1 Content attribute's opening quotation mark. * @type string[] $2 Content attribute's value for each meta element. * } * @param string $attr Attribute that identifies the element with the target metadata. * @param string $attr_value The attribute's value that identifies the element with the target metadata. * @return string The metadata on success. Empty string if not found. */ private function get_metadata_from_meta_element( $meta_elements, $attr, $attr_value ) { // Bail out if there are no meta elements. if ( empty( $meta_elements[0] ) ) { return ''; } $metadata = ''; $pattern = '#' . /* * Target this attribute and value to find the metadata element. * * Allows for (a) no, single, double quotes and (b) whitespace in the value. * * Why capture the opening quotation mark, i.e. (["\']), and then backreference, * i.e \1, for the closing quotation mark? * To ensure the closing quotation mark matches the opening one. Why? Attribute values * can contain quotation marks, such as an apostrophe in the content. */ $attr . '=([\"\']??)\s*' . $attr_value . '\s*\1' . /* * These are the options: * - i : case insensitive * - s : allows newline characters for the . match (needed for multiline elements) * - U means non-greedy matching */ '#isU'; // Find the metadata element. foreach ( $meta_elements[0] as $index => $element ) { preg_match( $pattern, $element, $match ); // This is not the metadata element. Skip it. if ( empty( $match ) ) { continue; } /* * Found the metadata element. * Get the metadata from its matching content array. */ if ( isset( $meta_elements[2][ $index ] ) && is_string( $meta_elements[2][ $index ] ) ) { $metadata = trim( $meta_elements[2][ $index ] ); } break; } return $metadata; } }

namespace = 'wp-block-editor/v1'; $this->rest_base = 'url-details'; } /** * Registers the necessary REST API routes. * * @since 5.9.0 */ public function register_routes() { register_rest_route( $this->namespace, '/' . $this->rest_base, array( array( 'methods' => WP_REST_Server::READABLE, 'callback' => array( $this, 'parse_url_details' ), 'args' => array( 'url' => array( 'required' => true, 'description' => __( 'The URL to process.' ), 'validate_callback' => 'wp_http_validate_url', 'sanitize_callback' => 'sanitize_url', 'type' => 'string', 'format' => 'uri', ), ), 'permission_callback' => array( $this, 'permissions_check' ), 'schema' => array( $this, 'get_public_item_schema' ), ), ) ); } /** * Retrieves the item's schema, conforming to JSON Schema. * * @since 5.9.0 * * @return array Item schema data. */ public function get_item_schema() { if ( $this->schema ) { return $this->add_additional_fields_schema( $this->schema ); } $this->schema = array( '$schema' => 'http://json-schema.org/draft-04/schema#', 'title' => 'url-details', 'type' => 'object', 'properties' => array( 'title' => array( 'description' => sprintf( /* translators: %s: HTML title tag. */ __( 'The contents of the %s element from the URL.' ), '' ), 'type' => 'string', 'context' => array( 'view', 'edit', 'embed' ), 'readonly' => true, ), 'icon' => array( 'description' => sprintf( /* translators: %s: HTML link tag. */ __( 'The favicon image link of the %s element from the URL.' ), '<link rel="icon">' ), 'type' => 'string', 'format' => 'uri', 'context' => array( 'view', 'edit', 'embed' ), 'readonly' => true, ), 'description' => array( 'description' => sprintf( /* translators: %s: HTML meta tag. */ __( 'The content of the %s element from the URL.' ), '<meta name="description">' ), 'type' => 'string', 'context' => array( 'view', 'edit', 'embed' ), 'readonly' => true, ), 'image' => array( 'description' => sprintf( /* translators: 1: HTML meta tag, 2: HTML meta tag. */ __( 'The Open Graph image link of the %1$s or %2$s element from the URL.' ), '<meta property="og:image">', '<meta property="og:image:url">' ), 'type' => 'string', 'format' => 'uri', 'context' => array( 'view', 'edit', 'embed' ), 'readonly' => true, ), ), ); return $this->add_additional_fields_schema( $this->schema ); } /** * Retrieves the contents of the title tag from the HTML response. * * @since 5.9.0 * * @param WP_REST_REQUEST $request Full details about the request. * @return WP_REST_Response|WP_Error The parsed details as a response object. WP_Error if there are errors. */ public function parse_url_details( $request ) { $url = untrailingslashit( $request['url'] ); if ( empty( $url ) ) { return new WP_Error( 'rest_invalid_url', __( 'Invalid URL' ), array( 'status' => 404 ) ); } // Transient per URL. $cache_key = $this->build_cache_key_for_url( $url ); // Attempt to retrieve cached response. $cached_response = $this->get_cache( $cache_key ); if ( ! empty( $cached_response ) ) { $remote_url_response = $cached_response; } else { $remote_url_response = $this->get_remote_url( $url ); // Exit if we don't have a valid body or it's empty. if ( is_wp_error( $remote_url_response ) || empty( $remote_url_response ) ) { return $remote_url_response; } // Cache the valid response. $this->set_cache( $cache_key, $remote_url_response ); } $html_head = $this->get_document_head( $remote_url_response ); $meta_elements = $this->get_meta_with_content_elements( $html_head ); $data = $this->add_additional_fields_to_object( array( 'title' => $this->get_title( $html_head ), 'icon' => $this->get_icon( $html_head, $url ), 'description' => $this->get_description( $meta_elements ), 'image' => $this->get_image( $meta_elements, $url ), ), $request ); // Wrap the data in a response object. $response = rest_ensure_response( $data ); /** * Filters the URL data for the response. * * @since 5.9.0 * * @param WP_REST_Response $response The response object. * @param string $url The requested URL. * @param WP_REST_Request $request Request object. * @param string $remote_url_response HTTP response body from the remote URL. */ return apply_filters( 'rest_prepare_url_details', $response, $url, $request, $remote_url_response ); } /** * Checks whether a given request has permission to read remote URLs. * * @since 5.9.0 * * @return WP_Error|bool True if the request has permission, else WP_Error. */ public function permissions_check() { if ( current_user_can( 'edit_posts' ) ) { return true; } foreach ( get_post_types( array( 'show_in_rest' => true ), 'objects' ) as $post_type ) { if ( current_user_can( $post_type->cap->edit_posts ) ) { return true; } } return new WP_Error( 'rest_cannot_view_url_details', __( 'Sorry, you are not allowed to process remote URLs.' ), array( 'status' => rest_authorization_required_code() ) ); } /** * Retrieves the document title from a remote URL. * * @since 5.9.0 * * @param string $url The website URL whose HTML to access. * @return string|WP_Error The HTTP response from the remote URL on success. * WP_Error if no response or no content. */ private function get_remote_url( $url ) { /* * Provide a modified UA string to workaround web properties which block WordPress "Pingbacks". * Why? The UA string used for pingback requests contains `WordPress/` which is very similar * to that used as the default UA string by the WP HTTP API. Therefore requests from this * REST endpoint are being unintentionally blocked as they are misidentified as pingback requests. * By slightly modifying the UA string, but still retaining the "WordPress" identification (via "WP") * we are able to work around this issue. * Example UA string: `WP-URLDetails/5.9-alpha-51389 (+http://localhost:8888)`. */ $modified_user_agent = 'WP-URLDetails/' . get_bloginfo( 'version' ) . ' (+' . get_bloginfo( 'url' ) . ')'; $args = array( 'limit_response_size' => 150 * KB_IN_BYTES, 'user-agent' => $modified_user_agent, ); /** * Filters the HTTP request args for URL data retrieval. * * Can be used to adjust response size limit and other WP_Http::request() args. * * @since 5.9.0 * * @param array $args Arguments used for the HTTP request. * @param string $url The attempted URL. */ $args = apply_filters( 'rest_url_details_http_request_args', $args, $url ); $response = wp_safe_remote_get( $url, $args ); if ( WP_Http::OK !== wp_remote_retrieve_response_code( $response ) ) { // Not saving the error response to cache since the error might be temporary. return new WP_Error( 'no_response', __( 'URL not found. Response returned a non-200 status code for this URL.' ), array( 'status' => WP_Http::NOT_FOUND ) ); } $remote_body = wp_remote_retrieve_body( $response ); if ( empty( $remote_body ) ) { return new WP_Error( 'no_content', __( 'Unable to retrieve body from response at this URL.' ), array( 'status' => WP_Http::NOT_FOUND ) ); } return $remote_body; } /** * Parses the title tag contents from the provided HTML. * * @since 5.9.0 * * @param string $html The HTML from the remote website at URL. * @return string The title tag contents on success. Empty string if not found. */ private function get_title( $html ) { $pattern = '#<title[^>]*>(.*?)<\s*/\s*title>#is'; preg_match( $pattern, $html, $match_title ); if ( empty( $match_title[1] ) || ! is_string( $match_title[1] ) ) { return ''; } $title = trim( $match_title[1] ); return $this->prepare_metadata_for_output( $title ); } /** * Parses the site icon from the provided HTML. * * @since 5.9.0 * * @param string $html The HTML from the remote website at URL. * @param string $url The target website URL. * @return string The icon URI on success. Empty string if not found. */ private function get_icon( $html, $url ) { // Grab the icon's link element. $pattern = '#<link\s[^>]*rel=(?:[\"\']??)\s*(?:icon|shortcut icon|icon shortcut)\s*(?:[\"\']??)[^>]*\/?>#isU'; preg_match( $pattern, $html, $element ); if ( empty( $element[0] ) || ! is_string( $element[0] ) ) { return ''; } $element = trim( $element[0] ); // Get the icon's href value. $pattern = '#href=([\"\']??)([^\" >]*?)\\1[^>]*#isU'; preg_match( $pattern, $element, $icon ); if ( empty( $icon[2] ) || ! is_string( $icon[2] ) ) { return ''; } $icon = trim( $icon[2] ); // If the icon is a data URL, return it. $parsed_icon = parse_url( $icon ); if ( isset( $parsed_icon['scheme'] ) && 'data' === $parsed_icon['scheme'] ) { return $icon; } // Attempt to convert relative URLs to absolute. if ( ! is_string( $url ) || '' === $url ) { return $icon; } $parsed_url = parse_url( $url ); if ( isset( $parsed_url['scheme'] ) && isset( $parsed_url['host'] ) ) { $root_url = $parsed_url['scheme'] . '://' . $parsed_url['host'] . '/'; $icon = WP_Http::make_absolute_url( $icon, $root_url ); } return $icon; } /** * Parses the meta description from the provided HTML. * * @since 5.9.0 * * @param array $meta_elements { * A multi-dimensional indexed array on success, else empty array. * * @type string[] $0 Meta elements with a content attribute. * @type string[] $1 Content attribute's opening quotation mark. * @type string[] $2 Content attribute's value for each meta element. * } * @return string The meta description contents on success. Empty string if not found. */ private function get_description( $meta_elements ) { // Bail out if there are no meta elements. if ( empty( $meta_elements[0] ) ) { return ''; } $description = $this->get_metadata_from_meta_element( $meta_elements, 'name', '(?:description|og:description)' ); // Bail out if description not found. if ( '' === $description ) { return ''; } return $this->prepare_metadata_for_output( $description ); } /** * Parses the Open Graph (OG) Image from the provided HTML. * * See: https://ogp.me/. * * @since 5.9.0 * * @param array $meta_elements { * A multi-dimensional indexed array on success, else empty array. * * @type string[] $0 Meta elements with a content attribute. * @type string[] $1 Content attribute's opening quotation mark. * @type string[] $2 Content attribute's value for each meta element. * } * @param string $url The target website URL. * @return string The OG image on success. Empty string if not found. */ private function get_image( $meta_elements, $url ) { $image = $this->get_metadata_from_meta_element( $meta_elements, 'property', '(?:og:image|og:image:url)' ); // Bail out if image not found. if ( '' === $image ) { return ''; } // Attempt to convert relative URLs to absolute. $parsed_url = parse_url( $url ); if ( isset( $parsed_url['scheme'] ) && isset( $parsed_url['host'] ) ) { $root_url = $parsed_url['scheme'] . '://' . $parsed_url['host'] . '/'; $image = WP_Http::make_absolute_url( $image, $root_url ); } return $image; } /** * Prepares the metadata by: * - stripping all HTML tags and tag entities. * - converting non-tag entities into characters. * * @since 5.9.0 * * @param string $metadata The metadata content to prepare. * @return string The prepared metadata. */ private function prepare_metadata_for_output( $metadata ) { $metadata = html_entity_decode( $metadata, ENT_QUOTES, get_bloginfo( 'charset' ) ); $metadata = wp_strip_all_tags( $metadata ); return $metadata; } /** * Utility function to build cache key for a given URL. * * @since 5.9.0 * * @param string $url The URL for which to build a cache key. * @return string The cache key. */ private function build_cache_key_for_url( $url ) { return 'g_url_details_response_' . md5( $url ); } /** * Utility function to retrieve a value from the cache at a given key. * * @since 5.9.0 * * @param string $key The cache key. * @return mixed The value from the cache. */ private function get_cache( $key ) { return get_site_transient( $key ); } /** * Utility function to cache a given data set at a given cache key. * * @since 5.9.0 * * @param string $key The cache key under which to store the value. * @param string $data The data to be stored at the given cache key. * @return bool True when transient set. False if not set. */ private function set_cache( $key, $data = '' ) { $ttl = HOUR_IN_SECONDS; /** * Filters the cache expiration. * * Can be used to adjust the time until expiration in seconds for the cache * of the data retrieved for the given URL. * * @since 5.9.0 * * @param int $ttl The time until cache expiration in seconds. */ $cache_expiration = apply_filters( 'rest_url_details_cache_expiration', $ttl ); return set_site_transient( $key, $data, $cache_expiration ); } /** * Retrieves the head element section. * * @since 5.9.0 * * @param string $html The string of HTML to parse. * @return string The `<head>..</head>` section on success. Given `$html` if not found. */ private function get_document_head( $html ) { $head_html = $html; // Find the opening `<head>` tag. $head_start = strpos( $html, '<head' ); if ( false === $head_start ) { // Didn't find it. Return the original HTML. return $html; } // Find the closing `</head>` tag. $head_end = strpos( $head_html, '</head>' ); if ( false === $head_end ) { // Didn't find it. Find the opening `<body>` tag. $head_end = strpos( $head_html, '<body' ); // Didn't find it. Return the original HTML. if ( false === $head_end ) { return $html; } } // Extract the HTML from opening tag to the closing tag. Then add the closing tag. $head_html = substr( $head_html, $head_start, $head_end ); $head_html .= '</head>'; return $head_html; } /** * Gets all the meta tag elements that have a 'content' attribute. * * @since 5.9.0 * * @param string $html The string of HTML to be parsed. * @return array { * A multi-dimensional indexed array on success, else empty array. * * @type string[] $0 Meta elements with a content attribute. * @type string[] $1 Content attribute's opening quotation mark. * @type string[] $2 Content attribute's value for each meta element. * } */ private function get_meta_with_content_elements( $html ) { /* * Parse all meta elements with a content attribute. * * Why first search for the content attribute rather than directly searching for name=description element? * tl;dr The content attribute's value will be truncated when it contains a > symbol. * * The content attribute's value (i.e. the description to get) can have HTML in it and be well-formed as * it's a string to the browser. Imagine what happens when attempting to match for the name=description * first. Hmm, if a > or /> symbol is in the content attribute's value, then it terminates the match * as the element's closing symbol. But wait, it's in the content attribute and is not the end of the * element. This is a limitation of using regex. It can't determine "wait a minute this is inside of quotation". * If this happens, what gets matched is not the entire element or all of the content. * * Why not search for the name=description and then content="(.*)"? * The attribute order could be opposite. Plus, additional attributes may exist including being between * the name and content attributes. * * Why not lookahead? * Lookahead is not constrained to stay within the element. The first <meta it finds may not include * the name or content, but rather could be from a different element downstream. */ $pattern = '#<meta\s' . /* * Allows for additional attributes before the content attribute. * Searches for anything other than > symbol. */ '[^>]*' . /* * Find the content attribute. When found, capture its value (.*). * * Allows for (a) single or double quotes and (b) whitespace in the value. * * Why capture the opening quotation mark, i.e. (["\']), and then backreference, * i.e \1, for the closing quotation mark? * To ensure the closing quotation mark matches the opening one. Why? Attribute values * can contain quotation marks, such as an apostrophe in the content. */ 'content=(["\']??)(.*)\1' . /* * Allows for additional attributes after the content attribute. * Searches for anything other than > symbol. */ '[^>]*' . /* * \/?> searches for the closing > symbol, which can be in either /> or > format. * # ends the pattern. */ '\/?>#' . /* * These are the options: * - i : case insensitive * - s : allows newline characters for the . match (needed for multiline elements) * - U means non-greedy matching */ 'isU'; preg_match_all( $pattern, $html, $elements ); return $elements; } /** * Gets the metadata from a target meta element. * * @since 5.9.0 * * @param array $meta_elements { * A multi-dimensional indexed array on success, else empty array. * * @type string[] $0 Meta elements with a content attribute. * @type string[] $1 Content attribute's opening quotation mark. * @type string[] $2 Content attribute's value for each meta element. * } * @param string $attr Attribute that identifies the element with the target metadata. * @param string $attr_value The attribute's value that identifies the element with the target metadata. * @return string The metadata on success. Empty string if not found. */ private function get_metadata_from_meta_element( $meta_elements, $attr, $attr_value ) { // Bail out if there are no meta elements. if ( empty( $meta_elements[0] ) ) { return ''; } $metadata = ''; $pattern = '#' . /* * Target this attribute and value to find the metadata element. * * Allows for (a) no, single, double quotes and (b) whitespace in the value. * * Why capture the opening quotation mark, i.e. (["\']), and then backreference, * i.e \1, for the closing quotation mark? * To ensure the closing quotation mark matches the opening one. Why? Attribute values * can contain quotation marks, such as an apostrophe in the content. */ $attr . '=([\"\']??)\s*' . $attr_value . '\s*\1' . /* * These are the options: * - i : case insensitive * - s : allows newline characters for the . match (needed for multiline elements) * - U means non-greedy matching */ '#isU'; // Find the metadata element. foreach ( $meta_elements[0] as $index => $element ) { preg_match( $pattern, $element, $match ); // This is not the metadata element. Skip it. if ( empty( $match ) ) { continue; } /* * Found the metadata element. * Get the metadata from its matching content array. */ if ( isset( $meta_elements[2][ $index ] ) && is_string( $meta_elements[2][ $index ] ) ) { $metadata = trim( $meta_elements[2][ $index ] ); } break; } return $metadata; } }