Fix all the examples

client.go

@@ -230,15 +230,15 @@ func (c *Client) Do(m *Msg, a string) {
 	c.QueryChan <- &Request{Client: c, Addr: a, Request: m}
 }
 
-// ExchangeBuffer performs a synchronous query. It sends the buffer m to the
+// exchangeBuffer performs a synchronous query. It sends the buffer m to the
 // address contained in a.
-func (c *Client) ExchangeBuffer(inbuf []byte, a string, outbuf []byte) (n int, err error) {
-	w := new(reply)
+func (c *Client) exchangeBuffer(inbuf []byte, a string, outbuf []byte) (n int, w *reply, err error) {
+	w = new(reply)
 	w.client = c
 	w.addr = a
 	if c.Hijacked == nil {
 		if err = w.Dial(); err != nil {
-			return 0, err
+			return 0, w, err
 		}
 		defer w.Close()
 	}
@@ -247,23 +247,23 @@ func (c *Client) ExchangeBuffer(inbuf []byte, a string, outbuf []byte) (n int, e
 	}
 	w.t = time.Now()
 	if n, err = w.writeClient(inbuf); err != nil {
-		return 0, err
+		return 0, w, err
 	}
 	if n, err = w.readClient(outbuf); err != nil {
-		return n, err
+		return n, w, err
 	}
-	// This rtt value isn't useful atm, need to return it somehow, TODO(mg)
 	w.rtt = time.Since(w.t)
-	return n, nil
+	return n, w, nil
 }
 
 // Exchange performs an synchronous query. It sends the message m to the address
 // contained in a and waits for an reply.
-func (c *Client) Exchange(m *Msg, a string) (r *Msg, err error) {
+func (c *Client) Exchange(m *Msg, a string) (r *Msg, rtt time.Duration, err error) {
 	var n int
+	var w *reply
 	out, ok := m.Pack()
 	if !ok {
-		return nil, ErrPack
+		return nil, 0, ErrPack
 	}
 	var in []byte
 	switch c.Net {
@@ -278,14 +278,14 @@ func (c *Client) Exchange(m *Msg, a string) (r *Msg, err error) {
 		}
 		in = make([]byte, size)
 	}
-	if n, err = c.ExchangeBuffer(out, a, in); err != nil {
-		return nil, err
+	if n, w, err = c.exchangeBuffer(out, a, in); err != nil {
+		return nil, 0, err
 	}
 	r = new(Msg)
 	if ok := r.Unpack(in[:n]); !ok {
-		return nil, ErrUnpack
+		return nil, w.rtt, ErrUnpack
 	}
-	return r, nil
+	return r, w.rtt, nil
 }
 
 // Dial connects to the address addr for the network set in c.Net

ex/chaos/chaos.go

@@ -27,14 +27,14 @@ func main() {
 	}
 	for _, a := range addr {
 		m.Question[0] = dns.Question{"version.bind.", dns.TypeTXT, dns.ClassCHAOS}
-		in, _ := c.Exchange(m, a)
+		in, rtt, _ := c.Exchange(m, a)
 		if in != nil && len(in.Answer) > 0  {
-			fmt.Printf("%v\n", in.Answer[0])
+			fmt.Printf("(time %.3d µs) %v\n", rtt/1e3, in.Answer[0])
 		}
 		m.Question[0] = dns.Question{"hostname.bind.", dns.TypeTXT, dns.ClassCHAOS}
-		in, _ = c.Exchange(m, a)
+		in, rtt, _ = c.Exchange(m, a)
 		if in != nil && len(in.Answer) > 0 {
-			fmt.Printf("%v\n", in.Answer[0])
+			fmt.Printf("(time %.3d µs) %v\n", rtt/1e3, in.Answer[0])
 		}
 	}
 }

ex/fp/fp.go

@@ -13,7 +13,7 @@ import (
 // returns a fingerprint.
 func probe(c *dns.Client, addr string, f *fingerprint) *fingerprint {
 	m := f.msg()
-	r, err := c.Exchange(m, addr)
+	r, _, err := c.Exchange(m, addr)
 	if err != nil {
 		return errorToFingerprint(err)
 	}

ex/key2ds/key2ds.go

@@ -21,7 +21,7 @@ func main() {
         m.SetEdns0(2048, true)
 
 	c := dns.NewClient()
-        r, _ := c.Exchange(m, conf.Servers[0] + ":" + conf.Port)
+        r, _, _ := c.Exchange(m, conf.Servers[0] + ":" + conf.Port)
 	if r == nil {
 		fmt.Printf("*** no answer received for %s\n", os.Args[1])
 		os.Exit(1)

ex/mx/mx.go

@@ -22,7 +22,7 @@ func main() {
 	m.MsgHdr.RecursionDesired = true
 
 	// Simple sync query, nothing fancy
-        r, err := c.Exchange(m, config.Servers[0] + ":" + config.Port)
+        r, _, err := c.Exchange(m, config.Servers[0] + ":" + config.Port)
 	if err != nil {
 		fmt.Printf("%s\n", err.Error())
 		os.Exit(1)

ex/q/q.go

@@ -27,8 +27,6 @@ func q(w dns.RequestWriter, m *dns.Msg) {
 	if w.TsigStatus() != nil {
 		fmt.Printf(";; Couldn't verify TSIG signature: %s\n", w.TsigStatus().Error())
 	}
-	// Save the Rtt in the message
-	// It's better to extend dns.RequestWriter...
 	w.Write(r)
 }
 
@@ -343,7 +341,7 @@ func getKey(name string, keytag uint16, server string, tcp bool) *dns.RR_DNSKEY
 	m := new(dns.Msg)
 	m.SetQuestion(name, dns.TypeDNSKEY)
 	m.SetEdns0(4096, true)
-	r, err := c.Exchange(m, server)
+	r, _, err := c.Exchange(m, server)
 	if err != nil {
 		return nil
 	}