Fix transport will modify input

quic/transport_http3.go

@@ -80,8 +80,9 @@ func (t *HTTP3Transport) Raw() bool {
 }
 
 func (t *HTTP3Transport) Exchange(ctx context.Context, message *mDNS.Msg) (*mDNS.Msg, error) {
-	message.Id = 0
-	rawMessage, err := message.Pack()
+	exMessage := *message
+	exMessage.Id = 0
+	rawMessage, err := exMessage.Pack()
 	if err != nil {
 		return nil, err
 	}

quic/transport_quic.go

@@ -121,8 +121,8 @@ func (t *Transport) Exchange(ctx context.Context, message *mDNS.Msg) (*mDNS.Msg,
 	)
 	for i := 0; i < 2; i++ {
 		conn, err = t.openConnection()
-		if conn == nil {
-			return nil, err
+		if err == nil {
+			break
 		}
 		response, err = t.exchange(ctx, message, conn)
 		if err == nil {
@@ -138,8 +138,9 @@ func (t *Transport) Exchange(ctx context.Context, message *mDNS.Msg) (*mDNS.Msg,
 }
 
 func (t *Transport) exchange(ctx context.Context, message *mDNS.Msg, conn quic.Connection) (*mDNS.Msg, error) {
-	message.Id = 0
-	rawMessage, err := message.Pack()
+	exMessage := *message
+	exMessage.Id = 0
+	rawMessage, err := exMessage.Pack()
 	if err != nil {
 		return nil, err
 	}

transport_base.go

@@ -114,42 +114,47 @@ func (t *myTransportAdapter) recvLoop(conn *dnsConnection) {
 
 func (t *myTransportAdapter) Exchange(ctx context.Context, message *dns.Msg) (*dns.Msg, error) {
 	messageId := message.Id
-	var response *dns.Msg
-	var err error
-	for attempts := 0; attempts < 3; attempts++ {
-		response, err = t.exchange(ctx, message)
-		if err != nil && !common.Done(ctx) {
-			continue
+	var (
+		conn *dnsConnection
+		err  error
+	)
+	for attempts := 0; attempts < 2; attempts++ {
+		conn, err = t.open(t.ctx)
+		if err == nil {
+			break
 		}
-		break
 	}
-	if err == nil {
-		response.Id = messageId
+	if err != nil {
+		return nil, err
 	}
-	return response, err
-}
-
-func (t *myTransportAdapter) exchange(ctx context.Context, message *dns.Msg) (*dns.Msg, error) {
-	conn, err := t.open(t.ctx)
+	response, err := t.exchange(ctx, conn, message)
 	if err != nil {
 		return nil, err
 	}
+	response.Id = messageId
+	return response, nil
+}
+
+func (t *myTransportAdapter) exchange(ctx context.Context, conn *dnsConnection, message *dns.Msg) (*dns.Msg, error) {
+	messageId := message.Id
 	callback := make(chan *dns.Msg)
+	exMessage := *message
 	conn.access.Lock()
 	conn.queryId++
-	message.Id = conn.queryId
-	conn.callbacks[message.Id] = callback
+	exMessage.Id = conn.queryId
+	conn.callbacks[exMessage.Id] = callback
 	conn.access.Unlock()
-	defer t.cleanup(conn, message.Id, callback)
+	defer t.cleanup(conn, exMessage.Id, callback)
 	conn.writeAccess.Lock()
-	err = t.handler.WriteMessage(conn, message)
+	err := t.handler.WriteMessage(conn, &exMessage)
 	conn.writeAccess.Unlock()
 	if err != nil {
 		conn.cancel()
 		return nil, err
 	}
 	select {
 	case response := <-callback:
+		response.Id = messageId
 		return response, nil
 	case <-conn.ctx.Done():
 		return nil, E.Errors(conn.err, conn.ctx.Err())

transport_https.go

@@ -69,8 +69,9 @@ func (t *HTTPSTransport) Raw() bool {
 }
 
 func (t *HTTPSTransport) Exchange(ctx context.Context, message *dns.Msg) (*dns.Msg, error) {
-	message.Id = 0
-	rawMessage, err := message.Pack()
+	exMessage := *message
+	exMessage.Id = 0
+	rawMessage, err := exMessage.Pack()
 	if err != nil {
 		return nil, err
 	}