fix an issue where untrusted contact's media message will never be marked as read

SessionMessagingKit/Messages/Signal/TSIncomingMessage.m

@@ -155,18 +155,26 @@ NS_ASSUME_NONNULL_BEGIN
     if (_read && readTimestamp >= self.expireStartedAt) {
         return;
     }
+    BOOL isTrusted = YES;
+    TSThread* thread = [self threadWithTransaction:transaction];
+    if ([thread isKindOfClass:[TSContactThread class]]) {
+        TSContactThread* contactThread = (TSContactThread*)thread;
+        isTrusted = [[LKStorage shared] getContactWithSessionID:[contactThread contactSessionID] using:transaction].isTrusted;
+    }
     
     BOOL areAllAttachmentsDownloaded = YES;
-    for (NSString *attachmentId in self.attachmentIds) {
-        TSAttachment *attachment = [TSAttachment fetchObjectWithUniqueID:attachmentId transaction:transaction];
-        // If the attachment download failed, we can mark this message as read.
-        // Otherwise, this message will never be marked as read.
-        if ([attachment isKindOfClass:[TSAttachmentPointer class]]
-            && ((TSAttachmentPointer *)attachment).state == TSAttachmentPointerStateFailed) {
-            continue;
+    if (isTrusted) {
+        for (NSString *attachmentId in self.attachmentIds) {
+            TSAttachment *attachment = [TSAttachment fetchObjectWithUniqueID:attachmentId transaction:transaction];
+            // If the attachment download failed, we can mark this message as read.
+            // Otherwise, this message will never be marked as read.
+            if ([attachment isKindOfClass:[TSAttachmentPointer class]]
+                && ((TSAttachmentPointer *)attachment).state == TSAttachmentPointerStateFailed) {
+                continue;
+            }
+            areAllAttachmentsDownloaded = areAllAttachmentsDownloaded && attachment.isDownloaded;
+            if (!areAllAttachmentsDownloaded) break;
         }
-        areAllAttachmentsDownloaded = areAllAttachmentsDownloaded && attachment.isDownloaded;
-        if (!areAllAttachmentsDownloaded) break;
     }
     
     if (!areAllAttachmentsDownloaded) {