Split FixedResponse

client.go

@@ -520,47 +520,13 @@ func (c *Client) exchangeToLookup(ctx context.Context, transport Transport, mess
 	if err != nil {
 		return nil, wrapError(err)
 	}
-	response := dns.Msg{
-		MsgHdr: dns.MsgHdr{
-			Id:       message.Id,
-			Rcode:    dns.RcodeSuccess,
-			Response: true,
-		},
-		Question: message.Question,
-	}
 	var timeToLive uint32
 	if rewriteTTL, loaded := RewriteTTLFromContext(ctx); loaded {
 		timeToLive = rewriteTTL
 	} else {
 		timeToLive = DefaultTTL
 	}
-	for _, address := range result {
-		if address.Is4In6() {
-			address = netip.AddrFrom4(address.As4())
-		}
-		if address.Is4() {
-			response.Answer = append(response.Answer, &dns.A{
-				Hdr: dns.RR_Header{
-					Name:   question.Name,
-					Rrtype: dns.TypeA,
-					Class:  dns.ClassINET,
-					Ttl:    timeToLive,
-				},
-				A: address.AsSlice(),
-			})
-		} else {
-			response.Answer = append(response.Answer, &dns.AAAA{
-				Hdr: dns.RR_Header{
-					Name:   question.Name,
-					Rrtype: dns.TypeAAAA,
-					Class:  dns.ClassINET,
-					Ttl:    timeToLive,
-				},
-				AAAA: address.AsSlice(),
-			})
-		}
-	}
-	return &response, nil
+	return FixedResponse(message.Id, question, result, timeToLive), nil
 }
 
 func (c *Client) lookupToExchange(ctx context.Context, transport Transport, name string, qType uint16, strategy DomainStrategy, responseChecker func(responseAddrs []netip.Addr) bool) ([]netip.Addr, error) {

transport_hosts.go

@@ -0,0 +1,42 @@
+package dns
+
+import (
+	"net/netip"
+
+	"github.com/miekg/dns"
+)
+
+func FixedResponse(id uint16, question dns.Question, addresses []netip.Addr, timeToLive uint32) *dns.Msg {
+	response := dns.Msg{
+		MsgHdr: dns.MsgHdr{
+			Id:       id,
+			Rcode:    dns.RcodeSuccess,
+			Response: true,
+		},
+		Question: []dns.Question{question},
+	}
+	for _, address := range addresses {
+		if address.Is4() {
+			response.Answer = append(response.Answer, &dns.A{
+				Hdr: dns.RR_Header{
+					Name:   question.Name,
+					Rrtype: dns.TypeA,
+					Class:  dns.ClassINET,
+					Ttl:    timeToLive,
+				},
+				A: address.AsSlice(),
+			})
+		} else {
+			response.Answer = append(response.Answer, &dns.AAAA{
+				Hdr: dns.RR_Header{
+					Name:   question.Name,
+					Rrtype: dns.TypeAAAA,
+					Class:  dns.ClassINET,
+					Ttl:    timeToLive,
+				},
+				AAAA: address.AsSlice(),
+			})
+		}
+	}
+	return &response
+}

transport_test.go

@@ -13,6 +13,7 @@ import (
 )
 
 func TestTransports(t *testing.T) {
+	t.Parallel()
 	serverAddressList := []string{
 		"114.114.114.114",
 		"tcp://114.114.114.114",
@@ -24,6 +25,7 @@ func TestTransports(t *testing.T) {
 	for _, serverAddressItem := range serverAddressList {
 		serverAddress := serverAddressItem
 		t.Run(serverAddress, func(t *testing.T) {
+			t.Parallel()
 			transport, err := dns.CreateTransport(dns.TransportOptions{
 				Context: context.Background(),
 				Logger:  logger.NOP(),