Support fetching private posts

src/Module/Objects.php

@@ -25,9 +25,11 @@ use Friendica\BaseModule;
 use Friendica\Core\System;
 use Friendica\Database\DBA;
 use Friendica\DI;
+use Friendica\Model\Contact;
 use Friendica\Model\Item;
 use Friendica\Network\HTTPException;
 use Friendica\Protocol\ActivityPub;
+use Friendica\Util\HTTPSignature;
 use Friendica\Util\Network;
 
 /**
@@ -45,17 +47,27 @@ class Objects extends BaseModule
 			DI::baseUrl()->redirect(str_replace('objects/', 'display/', DI::args()->getQueryString()));
 		}
 
-		/// @todo Add Authentication to enable fetching of non public content
-		// $requester = HTTPSignature::getSigner('', $_SERVER);
+		$item = Item::selectFirst(['id', 'uid', 'origin', 'author-link', 'changed', 'private', 'psid'],
+			['guid' => $parameters['guid']], ['order' => ['origin' => true]]);
+
+		$validated = false;
+		$requester = HTTPSignature::getSigner('', $_SERVER);
+		if (!empty($requester) && $item['origin']) {
+			$requester_id = Contact::getIdForURL($requester, $item['uid']);
+			if (!empty($requester_id)) {
+				$permissionSets = DI::permissionSet()->selectByContactId($requester_id, $item['uid']);
+				if (!empty($permissionSets)) {
+					$psid = array_merge($permissionSets->column('id'),
+						[DI::permissionSet()->getIdFromACL($item['uid'], '', '', '', '')]);
+					$validated = in_array($item['psid'], $psid);
+				}
+			}
+		}
+
+		if (!$validated && !in_array($item['private'], [Item::PUBLIC, Item::UNLISTED])) {
+			unset($item);
+		}
 
-		$item = Item::selectFirst(
-			['id', 'origin', 'author-link', 'changed'],
-			[
-				'guid' => $parameters['guid'],
-				'private' => [Item::PUBLIC, Item::UNLISTED]
-			],
-			['order' => ['origin' => true]]
-		);
 		// Valid items are original post or posted from this node (including in the case of a forum)
 		if (!DBA::isResult($item) || !$item['origin'] && (parse_url($item['author-link'], PHP_URL_HOST) != parse_url(DI::baseUrl()->get(), PHP_URL_HOST))) {
 			throw new HTTPException\NotFoundException();