core: new message decryption error - ratchet synchronization (#3367)

src/Simplex/Chat.hs

@@ -3635,6 +3635,7 @@ processAgentMessageConn user@User {userId} corrId agentConnId agentMessage = do
       RATCHET_HEADER -> (MDERatchetHeader, 1)
       RATCHET_EARLIER _ -> (MDERatchetEarlier, 1)
       RATCHET_SKIPPED n -> (MDETooManySkipped, n)
+      RATCHET_SYNC -> (MDERatchetSync, 0)
 
     mdeUpdatedCI :: (MsgDecryptError, Word32) -> CChatItem c -> Maybe (ChatItem c 'MDRcv, CIContent 'MDRcv)
     mdeUpdatedCI (mde', n') (CChatItem _ ci@ChatItem {content = CIRcvDecryptionError mde n})
@@ -3643,6 +3644,7 @@ processAgentMessageConn user@User {userId} corrId agentConnId agentMessage = do
         MDETooManySkipped -> r n' -- the numbers are not added as sequential MDETooManySkipped will have it incremented by 1
         MDERatchetEarlier -> r (n + n')
         MDEOther -> r (n + n')
+        MDERatchetSync -> r 0
       | otherwise = Nothing
       where
         r n'' = Just (ci, CIRcvDecryptionError mde n'')

src/Simplex/Chat/Messages/CIContent.hs

@@ -150,7 +150,12 @@ ciMsgContent = \case
   CIRcvMsgContent mc -> Just mc
   _ -> Nothing
 
-data MsgDecryptError = MDERatchetHeader | MDETooManySkipped | MDERatchetEarlier | MDEOther
+data MsgDecryptError
+  = MDERatchetHeader
+  | MDETooManySkipped
+  | MDERatchetEarlier
+  | MDEOther
+  | MDERatchetSync
   deriving (Eq, Show, Generic)
 
 instance ToJSON MsgDecryptError where
@@ -460,6 +465,7 @@ msgDecryptErrorText err n =
       MDETooManySkipped -> Just $ "too many skipped messages" <> counter
       MDERatchetEarlier -> Just $ "earlier message" <> counter
       MDEOther -> counter_
+      MDERatchetSync -> Just "synchronization error"
     counter_ = if n == 1 then Nothing else Just $ tshow n <> " messages"
     counter = maybe "" (", " <>) counter_