'; } } add_action( 'wp_head', 'independent_publisher_2_pingback_header' ); /** * Utility function to check if a gravatar exists for a given email or id * @param int|string|object $id_or_email A user ID, email address, or comment object * @return bool if the gravatar exists or not * @link https://gist.github.com/justinph/5197810 */ function validate_gravatar( $id_or_email ) { // The id or email code is borrowed from wp-includes/pluggable.php. $email = ''; if ( is_numeric( $id_or_email ) ) { $id = (int) $id_or_email; $user = get_userdata( $id ); if ( $user ) { $email = $user->user_email; } } elseif ( is_object( $id_or_email ) ) { // No avatar for pingbacks or trackbacks. $allowed_comment_types = apply_filters( 'get_avatar_comment_types', array( 'comment' ) ); if ( ! empty( $id_or_email->comment_type ) && ! in_array( $id_or_email->comment_type, (array) $allowed_comment_types, true ) ) { return false; } if ( ! empty( $id_or_email->user_id ) ) { $id = (int) $id_or_email->user_id; $user = get_userdata( $id ); if ( $user ) { $email = $user->user_email; } } elseif ( ! empty( $id_or_email->comment_author_email ) ) { $email = $id_or_email->comment_author_email; } } else { $email = $id_or_email; } $hashkey = md5( strtolower( trim( $email ) ) ); $uri = 'http://www.gravatar.com/avatar/' . $hashkey . '?d=404'; $data = wp_cache_get( $hashkey ); $expire = 60 * 5; $group = ''; if ( false === $data ) { $response = wp_remote_head( $uri ); if ( is_wp_error( $response ) ) { $data = 'not200'; } else { $data = $response['response']['code']; } wp_cache_set( $hashkey, $data, $group, $expire ); } if ( 200 === $data ) { return true; } else { return false; } }