Add AT Protocol DID endpoint

src/wp-admin/options-general.php

@@ -97,6 +97,20 @@
 <p class="description" id="tagline-description"><?php echo $tagline_description; ?></p></td>
 </tr>
 
+<tr>
+<th scope="row"><label for="atproto_did"><?php _e( 'AT Protocol DID' ); ?></label></th>
+<td><input name="atproto_did" type="text" id="atproto_did" aria-describedby="atproto-did-description" value="<?php form_option( 'atproto_did' ); ?>" class="regular-text code" />
+<p class="description" id="atproto-did-description">
+<?php
+printf(
+	/* translators: %s: .well-known URL path. */
+	__( 'Used to verify this domain as an AT Protocol handle. WordPress publishes it at %s.' ),
+	'<code>/.well-known/atproto-did</code>'
+);
+?>
+</p></td>
+</tr>
+
 <?php if ( current_user_can( 'upload_files' ) ) : ?>
 <tr class="hide-if-no-js site-icon-section">
 <th scope="row"><?php _e( 'Site Icon' ); ?></th>

src/wp-admin/options.php

@@ -91,6 +91,7 @@
 	'general'    => array(
 		'blogname',
 		'blogdescription',
+		'atproto_did',
 		'site_icon',
 		'gmt_offset',
 		'date_format',

src/wp-includes/atproto.php

@@ -0,0 +1,83 @@
+<?php
+/**
+ * AT Protocol functions.
+ *
+ * @package WordPress
+ * @subpackage ATProto
+ */
+
+/**
+ * Determines whether a value is a valid AT Protocol DID.
+ *
+ * @since 7.1.0
+ *
+ * @param mixed $did The value to check.
+ * @return bool Whether the value is a valid AT Protocol DID.
+ */
+function wp_is_atproto_did( $did ) {
+	if ( ! is_string( $did ) ) {
+		return false;
+	}
+
+	$did = trim( $did );
+
+	if ( '' === $did || str_contains( $did, "\n" ) || str_contains( $did, "\r" ) ) {
+		return false;
+	}
+
+	if ( preg_match( '/^did:plc:[a-z2-7]{24}$/', $did ) ) {
+		return true;
+	}
+
+	if ( preg_match( '/^did:web:localhost(?:%3[Aa][0-9]+)?$/', $did ) ) {
+		return true;
+	}
+
+	return (bool) preg_match( '/^did:web:(?:[a-z0-9](?:[a-z0-9-]{0,61}[a-z0-9])?\.)+[a-z](?:[a-z0-9-]{0,61}[a-z0-9])?$/', $did );
+}
+
+/**
+ * Retrieves the AT Protocol DID for this site.
+ *
+ * @since 7.1.0
+ *
+ * @return string The AT Protocol DID, or an empty string if one is not configured.
+ */
+function get_atproto_did() {
+	$did = get_option( 'atproto_did', '' );
+
+	/**
+	 * Filters the AT Protocol DID for this site.
+	 *
+	 * Returning an empty string disables the AT Protocol DID endpoint.
+	 *
+	 * @since 7.1.0
+	 *
+	 * @param string $did The configured AT Protocol DID.
+	 */
+	$did = apply_filters( 'atproto_did', $did );
+
+	if ( ! wp_is_atproto_did( $did ) ) {
+		return '';
+	}
+
+	return trim( $did );
+}
+
+/**
+ * Displays the AT Protocol DID document.
+ *
+ * @since 7.1.0
+ */
+function do_atproto_did() {
+	$did = get_atproto_did();
+
+	if ( '' === $did ) {
+		status_header( 404 );
+		nocache_headers();
+		return;
+	}
+
+	header( 'Content-Type: text/plain; charset=utf-8' );
+	echo $did;
+}

src/wp-includes/canonical.php

@@ -705,8 +705,9 @@ function redirect_canonical( $requested_url = null, $do_redirect = true ) {
 		$redirect['path'] = trailingslashit( $redirect['path'] );
 	}
 
-	// Remove trailing slash for robots.txt or sitemap requests.
+	// Remove trailing slash for robots.txt, sitemap, or AT Protocol DID requests.
 	if ( is_robots()
+		|| is_atproto_did()
 		|| ! empty( get_query_var( 'sitemap' ) ) || ! empty( get_query_var( 'sitemap-stylesheet' ) )
 	) {
 		$redirect['path'] = untrailingslashit( $redirect['path'] );

src/wp-includes/class-wp-query.php

@@ -410,6 +410,14 @@ class WP_Query {
 	 */
 	public $is_favicon = false;
 
+	/**
+	 * Signifies whether the current query is for the AT Protocol DID document.
+	 *
+	 * @since 7.1.0
+	 * @var bool
+	 */
+	public $is_atproto_did = false;
+
 	/**
 	 * Signifies whether the current query is for the page_for_posts page.
 	 *
@@ -519,6 +527,7 @@ private function init_query_flags() {
 		$this->is_singular          = false;
 		$this->is_robots            = false;
 		$this->is_favicon           = false;
+		$this->is_atproto_did       = false;
 		$this->is_posts_page        = false;
 		$this->is_post_type_archive = false;
 	}
@@ -817,6 +826,8 @@ public function parse_query( $query = '' ) {
 			$this->is_robots = true;
 		} elseif ( ! empty( $query_vars['favicon'] ) ) {
 			$this->is_favicon = true;
+		} elseif ( ! empty( $query_vars['atproto_did'] ) ) {
+			$this->is_atproto_did = true;
 		}
 
 		if ( ! is_scalar( $query_vars['p'] ) || (int) $query_vars['p'] < 0 ) {
@@ -1040,7 +1051,7 @@ public function parse_query( $query = '' ) {
 
 		if ( ! ( $this->is_singular || $this->is_archive || $this->is_search || $this->is_feed
 				|| ( wp_is_serving_rest_request() && $this->is_main_query() )
-				|| $this->is_trackback || $this->is_404 || $this->is_admin || $this->is_robots || $this->is_favicon ) ) {
+				|| $this->is_trackback || $this->is_404 || $this->is_admin || $this->is_robots || $this->is_favicon || $this->is_atproto_did ) ) {
 			$this->is_home = true;
 		}
 
@@ -4634,6 +4645,17 @@ public function is_favicon() {
 		return (bool) $this->is_favicon;
 	}
 
+	/**
+	 * Determines whether the query is for the AT Protocol DID document.
+	 *
+	 * @since 7.1.0
+	 *
+	 * @return bool Whether the query is for the AT Protocol DID document.
+	 */
+	public function is_atproto_did() {
+		return (bool) $this->is_atproto_did;
+	}
+
 	/**
 	 * Determines whether the query is for a search.
 	 *

src/wp-includes/class-wp-rewrite.php

@@ -1287,6 +1287,9 @@ public function rewrite_rules() {
 		// favicon.ico -- only if installed at the root.
 		$favicon_rewrite = ( empty( $home_path['path'] ) || '/' === $home_path['path'] ) ? array( 'favicon\.ico$' => $this->index . '?favicon=1' ) : array();
 
+		// .well-known/atproto-did -- only if installed at the root.
+		$atproto_did_rewrite = ( empty( $home_path['path'] ) || '/' === $home_path['path'] ) ? array( '\.well-known/atproto-did$' => $this->index . '?atproto_did=1' ) : array();
+
 		// sitemap.xml -- only if installed at the root.
 		$sitemap_rewrite = ( empty( $home_path['path'] ) || '/' === $home_path['path'] ) ? array( 'sitemap\.xml' => $this->index . '?sitemap=index' ) : array();
 
@@ -1452,9 +1455,9 @@ public function rewrite_rules() {
 
 		// Put them together.
 		if ( $this->use_verbose_page_rules ) {
-			$this->rules = array_merge( $this->extra_rules_top, $robots_rewrite, $favicon_rewrite, $sitemap_rewrite, $deprecated_files, $registration_pages, $root_rewrite, $comments_rewrite, $search_rewrite, $author_rewrite, $date_rewrite, $page_rewrite, $post_rewrite, $this->extra_rules );
+			$this->rules = array_merge( $this->extra_rules_top, $robots_rewrite, $favicon_rewrite, $atproto_did_rewrite, $sitemap_rewrite, $deprecated_files, $registration_pages, $root_rewrite, $comments_rewrite, $search_rewrite, $author_rewrite, $date_rewrite, $page_rewrite, $post_rewrite, $this->extra_rules );
 		} else {
-			$this->rules = array_merge( $this->extra_rules_top, $robots_rewrite, $favicon_rewrite, $sitemap_rewrite, $deprecated_files, $registration_pages, $root_rewrite, $comments_rewrite, $search_rewrite, $author_rewrite, $date_rewrite, $post_rewrite, $page_rewrite, $this->extra_rules );
+			$this->rules = array_merge( $this->extra_rules_top, $robots_rewrite, $favicon_rewrite, $atproto_did_rewrite, $sitemap_rewrite, $deprecated_files, $registration_pages, $root_rewrite, $comments_rewrite, $search_rewrite, $author_rewrite, $date_rewrite, $post_rewrite, $page_rewrite, $this->extra_rules );
 		}
 
 		/**

src/wp-includes/class-wp.php

@@ -15,7 +15,7 @@ class WP {
 	 * @since 2.0.0
 	 * @var string[]
 	 */
-	public $public_query_vars = array( 'm', 'p', 'posts', 'w', 'cat', 'withcomments', 'withoutcomments', 's', 'search', 'exact', 'sentence', 'calendar', 'page', 'paged', 'more', 'tb', 'pb', 'author', 'order', 'orderby', 'year', 'monthnum', 'day', 'hour', 'minute', 'second', 'name', 'category_name', 'tag', 'feed', 'author_name', 'pagename', 'page_id', 'error', 'attachment', 'attachment_id', 'subpost', 'subpost_id', 'preview', 'robots', 'favicon', 'taxonomy', 'term', 'cpage', 'post_type', 'embed' );
+	public $public_query_vars = array( 'm', 'p', 'posts', 'w', 'cat', 'withcomments', 'withoutcomments', 's', 'search', 'exact', 'sentence', 'calendar', 'page', 'paged', 'more', 'tb', 'pb', 'author', 'order', 'orderby', 'year', 'monthnum', 'day', 'hour', 'minute', 'second', 'name', 'category_name', 'tag', 'feed', 'author_name', 'pagename', 'page_id', 'error', 'attachment', 'attachment_id', 'subpost', 'subpost_id', 'preview', 'robots', 'favicon', 'atproto_did', 'taxonomy', 'term', 'cpage', 'post_type', 'embed' );
 
 	/**
 	 * Private query variables.
@@ -746,8 +746,8 @@ public function handle_404() {
 
 		$set_404 = true;
 
-		// Never 404 for the admin, robots, or favicon.
-		if ( is_admin() || is_robots() || is_favicon() ) {
+		// Never 404 for the admin, robots, favicon, or AT Protocol DID endpoint.
+		if ( is_admin() || is_robots() || is_favicon() || is_atproto_did() ) {
 			$set_404 = false;
 
 			// If posts were found, check for paged content.

src/wp-includes/default-filters.php

@@ -550,6 +550,9 @@
 // Sitemaps actions.
 add_action( 'init', 'wp_sitemaps_get_server' );
 
+// AT Protocol actions.
+add_action( 'do_atproto_did', 'do_atproto_did' );
+
 /**
  * Filters formerly mixed into wp-includes.
  */

src/wp-includes/formatting.php

@@ -5003,6 +5003,13 @@ function sanitize_option( $option, $value ) {
 			}
 			break;
 
+		case 'atproto_did':
+			$value = is_string( $value ) ? trim( $value ) : '';
+			if ( '' !== $value && ! wp_is_atproto_did( $value ) ) {
+				$error = __( 'The AT Protocol DID you entered did not appear to be valid. Please enter a did:plc or did:web identifier.' );
+			}
+			break;
+
 		case 'date_format':
 		case 'time_format':
 		case 'mailserver_url':

src/wp-includes/option.php

@@ -2765,6 +2765,18 @@ function register_initial_settings() {
 		)
 	);
 
+	register_setting(
+		'general',
+		'atproto_did',
+		array(
+			'show_in_rest' => true,
+			'type'         => 'string',
+			'label'        => __( 'AT Protocol DID' ),
+			'description'  => __( 'A decentralized identifier for AT Protocol handle verification.' ),
+			'default'      => '',
+		)
+	);
+
 	if ( ! is_multisite() ) {
 		register_setting(
 			'general',

src/wp-includes/query.php

@@ -680,6 +680,26 @@ function is_favicon() {
 	return $wp_query->is_favicon();
 }
 
+/**
+ * Is the query for the AT Protocol DID document?
+ *
+ * @since 7.1.0
+ *
+ * @global WP_Query $wp_query WordPress Query object.
+ *
+ * @return bool Whether the query is for the AT Protocol DID document.
+ */
+function is_atproto_did() {
+	global $wp_query;
+
+	if ( ! isset( $wp_query ) ) {
+		_doing_it_wrong( __FUNCTION__, __( 'Conditional query tags do not work before the query is run. Before then, they always return false.' ), '3.1.0' );
+		return false;
+	}
+
+	return $wp_query->is_atproto_did();
+}
+
 /**
  * Determines whether the query is for a search.
  *

src/wp-includes/template-loader.php

@@ -54,6 +54,14 @@
 	 */
 	do_action( 'do_favicon' );
 	return;
+} elseif ( is_atproto_did() ) {
+	/**
+	 * Fired when the template loader determines an AT Protocol DID request.
+	 *
+	 * @since 7.1.0
+	 */
+	do_action( 'do_atproto_did' );
+	return;
 } elseif ( is_feed() ) {
 	do_feed();
 	return;

src/wp-settings.php

@@ -115,6 +115,7 @@
 require ABSPATH . WPINC . '/formatting.php';
 require ABSPATH . WPINC . '/meta.php';
 require ABSPATH . WPINC . '/functions.php';
+require ABSPATH . WPINC . '/atproto.php';
 require ABSPATH . WPINC . '/class-wp-meta-query.php';
 require ABSPATH . WPINC . '/class-wp-matchesmapregex.php';
 require ABSPATH . WPINC . '/class-wp.php';

tests/phpunit/tests/atproto.php

@@ -0,0 +1,72 @@
+<?php
+/**
+ * Tests for AT Protocol functions.
+ *
+ * @package WordPress
+ *
+ * @group atproto
+ */
+class Tests_ATProto extends WP_UnitTestCase {
+
+	public function tear_down() {
+		delete_option( 'atproto_did' );
+		remove_all_filters( 'atproto_did' );
+		parent::tear_down();
+	}
+
+	/**
+	 * @dataProvider data_wp_is_atproto_did
+	 *
+	 * @covers ::wp_is_atproto_did
+	 */
+	public function test_wp_is_atproto_did( $did, $expected ) {
+		$this->assertSame( $expected, wp_is_atproto_did( $did ) );
+	}
+
+	public function data_wp_is_atproto_did() {
+		return array(
+			'did:plc'            => array( 'did:plc:ewvi7nxzyoun6zhxrhs64oiz', true ),
+			'did:web domain'     => array( 'did:web:example.com', true ),
+			'did:web localhost'  => array( 'did:web:localhost%3A3000', true ),
+			'empty'              => array( '', false ),
+			'invalid method'     => array( 'did:key:z6MkiTBzTbWb4TLEt', false ),
+			'invalid plc length' => array( 'did:plc:abc', false ),
+			'did:web path'       => array( 'did:web:example.com%3Ausers%3Aalice', false ),
+			'did:web uppercase'  => array( 'did:web:Example.com', false ),
+			'newline'            => array( "did:web:example.com\ninvalid", false ),
+			'non-string'         => array( 123, false ),
+		);
+	}
+
+	/**
+	 * @covers ::get_atproto_did
+	 */
+	public function test_get_atproto_did_returns_option_value() {
+		update_option( 'atproto_did', 'did:web:example.com' );
+
+		$this->assertSame( 'did:web:example.com', get_atproto_did() );
+	}
+
+	/**
+	 * @covers ::get_atproto_did
+	 */
+	public function test_get_atproto_did_applies_filter() {
+		add_filter(
+			'atproto_did',
+			static function () {
+				return 'did:plc:ewvi7nxzyoun6zhxrhs64oiz';
+			}
+		);
+
+		$this->assertSame( 'did:plc:ewvi7nxzyoun6zhxrhs64oiz', get_atproto_did() );
+	}
+
+	/**
+	 * @covers ::get_atproto_did
+	 */
+	public function test_get_atproto_did_returns_empty_string_for_invalid_did() {
+		add_option( 'atproto_did', 'invalid' );
+
+		$this->assertSame( '', get_atproto_did() );
+	}
+}