Relay settings are now valid for the ActivityRelay as well

src/Model/Search.php

@@ -42,7 +42,7 @@ class Search
 		$tags = [];
 
 		while ($term = DBA::fetch($termsStmt)) {
-			$tags[] = trim($term['term'], '#');
+			$tags[] = trim(mb_strtolower($term['term']), '#');
 		}
 		DBA::close($termsStmt);
 		return $tags;

src/Module/Admin/Site.php

@@ -691,8 +691,8 @@ class Site extends BaseAdmin
 			'$worker_fastlane'        => ['worker_fastlane', DI::l10n()->t('Enable fastlane'), DI::config()->get('system', 'worker_fastlane'), DI::l10n()->t('When enabed, the fastlane mechanism starts an additional worker if processes with higher priority are blocked by processes of lower priority.')],
 			'$worker_frontend'        => ['worker_frontend', DI::l10n()->t('Enable frontend worker'), DI::config()->get('system', 'frontend_worker'), DI::l10n()->t('When enabled the Worker process is triggered when backend access is performed (e.g. messages being delivered). On smaller sites you might want to call %s/worker on a regular basis via an external cron job. You should only enable this option if you cannot utilize cron/scheduled jobs on your server.', DI::baseUrl()->get())],
 
-			'$relay_subscribe'        => ['relay_subscribe', DI::l10n()->t('Subscribe to relay'), DI::config()->get('system', 'relay_subscribe'), DI::l10n()->t('Enables the receiving of public posts from the relay. They will be included in the search, subscribed tags and on the global community page.')],
-			'$relay_server'           => ['relay_server', DI::l10n()->t('Relay server'), DI::config()->get('system', 'relay_server'), DI::l10n()->t('Address of the relay server where public posts should be send to. For example %s', 'https://social-relay.isurf.ca')],
+			'$relay_subscribe'        => ['relay_subscribe', DI::l10n()->t('Use relay servers'), DI::config()->get('system', 'relay_subscribe'), DI::l10n()->t('Enables the receiving of public posts from relay servers. They will be included in the search, subscribed tags and on the global community page.')],
+			'$relay_server'           => ['relay_server', DI::l10n()->t('"Social Relay" server'), DI::config()->get('system', 'relay_server'), DI::l10n()->t('Address of the "Social Relay" server where public posts should be send to. For example %s. ActivityRelay servers are administrated via the "console relay" command line command.', 'https://social-relay.isurf.ca')],
 			'$relay_directly'         => ['relay_directly', DI::l10n()->t('Direct relay transfer'), DI::config()->get('system', 'relay_directly'), DI::l10n()->t('Enables the direct transfer to other servers without using the relay servers')],
 			'$relay_scope'            => ['relay_scope', DI::l10n()->t('Relay scope'), DI::config()->get('system', 'relay_scope'), DI::l10n()->t('Can be "all" or "tags". "all" means that every public post should be received. "tags" means that only posts with selected tags should be received.'), ['' => DI::l10n()->t('Disabled'), 'all' => DI::l10n()->t('all'), 'tags' => DI::l10n()->t('tags')]],
 			'$relay_server_tags'      => ['relay_server_tags', DI::l10n()->t('Server tags'), DI::config()->get('system', 'relay_server_tags'), DI::l10n()->t('Comma separated list of tags for the "tags" subscription.')],

src/Protocol/ActivityPub/Processor.php

@@ -35,6 +35,7 @@ use Friendica\Model\Event;
 use Friendica\Model\Item;
 use Friendica\Model\ItemURI;
 use Friendica\Model\Mail;
+use Friendica\Model\Search;
 use Friendica\Model\Tag;
 use Friendica\Model\User;
 use Friendica\Protocol\Activity;
@@ -767,6 +768,10 @@ class Processor
 		$ldactivity['thread-completion'] = true;
 		$ldactivity['from-relay'] = Contact::getIdForURL($relay_actor);
 
+		if (!empty($relay_actor) && !self::acceptIncomingMessage($ldactivity, $object['id'])) {
+			return '';
+		}
+
 		ActivityPub\Receiver::processActivity($ldactivity, json_encode($activity), $uid, true, false, $signer);
 
 		Logger::notice('Activity had been fetched and processed.', ['url' => $url, 'object' => $activity['id']]);
@@ -774,6 +779,92 @@ class Processor
 		return $activity['id'];
 	}
 
+	/**
+	 * Test if incoming relay messages should be accepted
+	 *
+	 * @param array $activity activity array
+	 * @param string $id      object ID
+	 * @return boolean true if message is accepted
+	 */
+	private static function acceptIncomingMessage(array $activity, string $id)
+	{
+		if (empty($activity['as:object'])) {
+			Logger::info('No object field in activity - accepted', ['id' => $id]);
+			return true;
+		}
+
+		$config = DI::config();
+
+		$subscribe = $config->get('system', 'relay_subscribe', false);
+		if ($subscribe) {
+			$scope = $config->get('system', 'relay_scope', SR_SCOPE_ALL);
+		} else {
+			$scope = SR_SCOPE_NONE;
+		}
+
+		if ($scope == SR_SCOPE_ALL) {
+			Logger::info('Server accept all posts - accepted', ['id' => $id]);
+			return true;
+		}
+
+		$replyto = JsonLD::fetchElement($activity['as:object'], 'as:inReplyTo', '@id');
+		if (Item::exists(['uri' => $replyto])) {
+			Logger::info('Post is a reply to an existing post - accepted', ['id' => $id, 'replyto' => $replyto]);
+			return true;
+		}
+
+		if ($scope == SR_SCOPE_NONE) {
+			Logger::info('Server does not accept relay posts - rejected', ['id' => $id]);
+			return false;
+		}
+
+		$messageTags = [];
+		$tags = Receiver::processTags(JsonLD::fetchElementArray($activity['as:object'], 'as:tag') ?? []);
+		if (!empty($tags)) {
+			foreach ($tags as $tag) {
+				if ($tag['type'] != 'Hashtag') {
+					continue;
+				}
+				$messageTags[] = ltrim(mb_strtolower($tag['name']), '#');
+			}
+		}
+
+		$systemTags = [];
+		$userTags = [];
+
+		if ($scope == SR_SCOPE_TAGS) {
+			$server_tags = $config->get('system', 'relay_server_tags', []);
+			$tagitems = explode(',', mb_strtolower($server_tags));
+
+			foreach ($tagitems AS $tag) {
+				$systemTags[] = trim($tag, '# ');
+			}
+
+			if ($config->get('system', 'relay_user_tags')) {
+				$userTags = Search::getUserTags();
+			}
+		}
+
+		$content = mb_strtolower(JsonLD::fetchElement($activity['as:object'], 'as:content', '@value'));
+
+		$tagList = array_unique(array_merge($systemTags, $userTags));
+		foreach ($messageTags as $tag) {
+			if (in_array($tag, $tagList)) {
+				Logger::info('Subscribed hashtag found - accepted', ['id' => $id, 'hashtag' => $tag]);
+				return true;
+			}
+			// We check with "strpos" for performance issues. Only when this is true, the regular expression check is used
+			// RegExp is taken from here: https://medium.com/@shiba1014/regex-word-boundaries-with-unicode-207794f6e7ed
+			if ((strpos($content, $tag) !== false) && preg_match('/(?<=[\s,.:;"\']|^)' . $tag . '(?=[\s,.:;"\']|$)/', $content)) {
+				Logger::info('Subscribed hashtag found in content - accepted', ['id' => $id, 'hashtag' => $tag]);
+				return true;
+			}
+		}
+
+		Logger::info('No matching hashtags found - rejected', ['id' => $id]);
+		return false;
+	}
+
 	/**
 	 * perform a "follow" request
 	 *

src/Protocol/ActivityPub/Receiver.php

@@ -181,7 +181,11 @@ class Receiver
 			return;
 		}
 
-		Processor::fetchMissingActivity($object_id, [], $actor);
+		$id = Processor::fetchMissingActivity($object_id, [], $actor);
+		if (empty($id)) {
+			Logger::notice('Relayed message had not been fetched', ['id' => $object_id]);
+			return;
+		}
 
 		$item_id = Item::searchByLink($object_id);
 		if ($item_id) {
@@ -964,7 +968,7 @@ class Receiver
 	 *
 	 * @return array with tags in a simplified format
 	 */
-	private static function processTags(array $tags)
+	public static function processTags(array $tags)
 	{
 		$taglist = [];