Merge pull request #325 from miekg/issue-324

Issue 324

client.go

@@ -258,7 +258,7 @@ func (co *Conn) ReadMsgHeader(hdr *Header) ([]byte, error) {
 		}
 		p = make([]byte, l)
 		n, err = tcpRead(r, p)
-
+		co.rtt = time.Since(co.t)
 	default:
 		if co.UDPSize > MinMsgSize {
 			p = make([]byte, co.UDPSize)
@@ -266,6 +266,7 @@ func (co *Conn) ReadMsgHeader(hdr *Header) ([]byte, error) {
 			p = make([]byte, MinMsgSize)
 		}
 		n, err = co.Read(p)
+		co.rtt = time.Since(co.t)
 	}
 
 	if err != nil {
@@ -342,8 +343,6 @@ func (co *Conn) Read(p []byte) (n int, err error) {
 	if err != nil {
 		return n, err
 	}
-
-	co.rtt = time.Since(co.t)
 	return n, err
 }
 

issue_test.go

@@ -0,0 +1,23 @@
+package dns
+
+// Tests that solve that an specific issue.
+
+import "testing"
+
+func TestTCPRtt(t *testing.T) {
+	m := new(Msg)
+	m.RecursionDesired = true
+	m.SetQuestion("example.org.", TypeA)
+
+	c := &Client{}
+	for _, proto := range []string{"udp", "tcp"} {
+		c.Net = proto
+		_, rtt, err := c.Exchange(m, "8.8.4.4:53")
+		if err != nil {
+			t.Fatal(err)
+		}
+		if rtt == 0 {
+			t.Fatalf("expecting non zero rtt %s, got zero", c.Net)
+		}
+	}
+}