METADAPT-A handles closing messages

metadapta.go

@@ -7,6 +7,7 @@ import "sync"
 import "git.tebibyte.media/sashakoshka/hopp/tape"
 import "git.tebibyte.media/sashakoshka/go-util/sync"
 
+const closeMethod = 0xFFFF
 const int64Max = int64((^uint64(0)) >> 1)
 
 // Party represents a side of a connection.
@@ -169,6 +170,7 @@ func (this *transA) Close() error {
 }
 
 func (this *transA) closeDontUnlist() error {
+	this.Send(closeMethod, nil)
 	return this.incoming.Close()
 }
 
@@ -184,10 +186,14 @@ func (this *transA) Receive() (method uint16, data []byte, err error) {
 	receive := this.incoming.Receive()
 	if receive != nil {
 		if message, ok := <- receive; ok {
-			return message.method, message.payload, nil
+			if message.method != closeMethod {
+				return message.method, message.payload, nil
+			}
 		}
 	}
-	
+
+	// close and return error on failure
+	this.Close()
 	if this.parent.err == nil {
 		return 0, nil, fmt.Errorf("could not receive message: %w", io.EOF)
 	} else {