add blacklist settings

includes/class-admin.php

@@ -106,6 +106,14 @@ class Admin {
 				'default'      => array( 'post', 'pages' ),
 			)
 		);
+		\register_setting(
+			'activitypub', 'activitypub_blacklist', array(
+				'type'         => 'string',
+				'description'  => \esc_html__( 'Block fediverse instances', 'activitypub' ),
+				'show_in_rest' => true,
+				'default'      => 'gab.com',
+			)
+		);
 	}
 
 	public static function add_settings_help_tab() {

includes/functions.php

@@ -287,3 +287,50 @@ function url_to_authorid( $url ) {
 
 	return 0;
 }
+
+/**
+ * Get the blacklist from the WordPress options table
+ *
+ * @return array the list of blacklisted hosts
+ *
+ * @uses apply_filters() Calls 'activitypub_blacklist' filter
+ */
+function get_blacklist() {
+	$blacklist = \get_option( 'activitypub_blacklist' );
+	$blacklist_hosts  = \explode( PHP_EOL, $blacklist );
+
+	// if no values have been set, revert to the defaults
+	if ( ! $blacklist || ! $blacklist_hosts || ! is_array( $blacklist_hosts ) ) {
+		$blacklist_hosts = array(
+			'gab.com',
+		);
+	}
+
+	// clean out any blank values
+	foreach ( $blacklist_hosts as $key => $value ) {
+		if ( empty( $value ) ) {
+			unset( $blacklist_hosts[ $key ] );
+		} else {
+			$blacklist_hosts[ $key ] = \trim( $blacklist_hosts[ $key ] );
+		}
+	}
+
+	return \apply_filters( 'activitypub_blacklist', $blacklist_hosts );
+}
+
+/**
+ * Check if an URL is blacklisted
+ *
+ * @param string $url an URL to check
+ *
+ * @return boolean
+ */
+function is_blacklisted( $url ) {
+	foreach ( \ActivityPub\get_blacklist() as $blacklisted_host ) {
+		if ( \strpos( $url, $blacklisted_host ) !== false ) {
+			return true;
+		}
+	}
+
+	return false;
+}

templates/settings.php

@@ -90,6 +90,31 @@
 
 		<?php \do_settings_fields( 'activitypub', 'activity' ); ?>
 
+		<h2><?php \esc_html_e( 'Server', 'activitypub' ); ?></h2>
+
+		<p><?php \esc_html_e( 'Server related settings.', 'activitypub' ); ?></p>
+
+		<?php
+		// load the existing blacklist from the WordPress options table
+		$activitypub_blacklist = \trim( \implode( PHP_EOL, \ActivityPub\get_blacklist() ), PHP_EOL );
+		?>
+
+		<table class="form-table">
+			<tbody>
+				<tr>
+					<th scope="row">
+						<?php \esc_html_e( 'Blacklist', 'activitypub' ); ?>
+					</th>
+					<td>
+						<textarea name="activitypub_blacklist" id="activitypub_blacklist" rows="10" cols="50" class="large-text"><?php echo $activitypub_blacklist; ?></textarea>
+						<p class="description"><?php \_e( 'A list of hosts, you want to block, one host per line. Please use only the host/domain of the server you want to block, without <code>http://</code> and without <code>www.</code>. For example <code>example.com</code>.', 'activitypub' ); ?></p>
+					</td>
+				</tr>
+			</tbody>
+		</table>
+
+		<?php \do_settings_fields( 'activitypub', 'server' ); ?>
+
 		<?php \do_settings_sections( 'activitypub' ); ?>
 
 		<?php \submit_button(); ?>