only write to listener's app relayers

relayer/listener.go

@@ -192,7 +192,12 @@ func (lstnr *Listener) processLogs(ctx context.Context) error {
 				return fmt.Errorf("failed to catch up on historical blocks")
 			}
 		case blockHeader := <-lstnr.Subscriber.Headers():
-			go lstnr.messageCoordinator.ProcessBlock(blockHeader, lstnr.ethClient, errChan)
+			go lstnr.messageCoordinator.ProcessBlock(
+				blockHeader,
+				lstnr.sourceBlockchain.GetBlockchainID(),
+				lstnr.ethClient,
+				errChan,
+			)
 		case err := <-lstnr.Subscriber.Err():
 			lstnr.healthStatus.Store(false)
 			lstnr.logger.Error(

relayer/message_coordinator.go

@@ -224,6 +224,7 @@ func (mc *MessageCoordinator) ProcessMessageID(
 // Meant to be ran asynchronously. Errors should be sent to errChan.
 func (mc *MessageCoordinator) ProcessBlock(
 	blockHeader *types.Header,
+	blockchainID ids.ID,
 	ethClient ethclient.Client,
 	errChan chan error,
 ) {
@@ -256,6 +257,9 @@ func (mc *MessageCoordinator) ProcessBlock(
 	}
 	// Initiate message relay of all registered messages
 	for _, appRelayer := range mc.applicationRelayers {
+		if appRelayer.sourceBlockchain.GetBlockchainID() != blockchainID {
+			continue
+		}
 		// Dispatch all messages in the block to the appropriate application relayer.
 		// An empty slice is still a valid argument to ProcessHeight; in this case the height is immediately committed.
 		handlers := messageHandlers[appRelayer.relayerID.ID]