fix: catch discard error and return

Signed-off-by: ningmingxiao <ning.mingxiao@zte.com.cn>

Author: ningmingxiao

channel.go

@@ -125,7 +125,7 @@ func (ch *channel) recv() (messageHeader, []byte, error) {
 
 	if mh.Length > uint32(messageLengthMax) {
 		if _, err := ch.br.Discard(int(mh.Length)); err != nil {
-			return mh, nil, fmt.Errorf("failed to discard after receiving oversized message: %w", err)
+			return mh, nil, DiscardError(fmt.Errorf("discard failed %w ,message length %v maximum message size %v", err, mh.Length, messageLengthMax))
 		}
 
 		return mh, nil, status.Errorf(codes.ResourceExhausted, "message length %v exceed maximum message size of %v", mh.Length, messageLengthMax)

errors.go

@@ -78,3 +78,20 @@ func (e *OversizedMessageErr) RejectedLength() int {
 func (*OversizedMessageErr) MaximumLength() int {
 	return messageLengthMax
 }
+
+type DiscardErr struct {
+	err error
+}
+
+func (d *DiscardErr) Error() string {
+	return d.err.Error()
+}
+
+func DiscardError(err error) error {
+	if err == nil {
+		return nil
+	}
+	return &DiscardErr{
+		err: err,
+	}
+}

server.go

@@ -559,6 +559,11 @@ func (c *serverConn) run(sctx context.Context) {
 				// requests, so that the client connection is closed
 				return
 			}
+
+			if _, ok := err.(*DiscardErr); ok {
+				log.G(ctx).WithError(err).Error("discard failed")
+				return
+			}
 			log.G(ctx).WithError(err).Error("error receiving message")
 			// else, initiate shutdown
 		case <-shutdown: