Save rtts for clients

client.go

@@ -13,10 +13,7 @@ import (
 	"time"
 )
 
-// Check incoming TSIG message. TODO(mg)
-// Need a tsigstatus for that too? Don't know yet. TODO(mg)
-
-// Incoming (just as in os.Signal)
+// Incoming (documentation just as in os.Signal)
 type QueryHandler interface {
 	QueryDNS(w RequestWriter, q *Msg)
 }
@@ -32,10 +29,12 @@ type RequestWriter interface {
 	Receive() (*Msg, error)
 	// Close closes the connection with the server.
 	Close() error
-	// Dials calls the server
+	// Dials calls the server.
 	Dial() error
-	// TsigStatus return the TSIG validation status.
+	// TsigStatus returns the TSIG validation status.
 	TsigStatus() error
+	// Rtt returns the duration of the request. The value is only valid after a Send()/Receive() sequence.
+	Rtt() time.Duration
 }
 
 // hijacked connections...?
@@ -47,6 +46,8 @@ type reply struct {
 	tsigRequestMAC string
 	tsigTimersOnly bool
 	tsigStatus     error
+	rtt            time.Duration
+	t              time.Time
 }
 
 // A Request is a incoming message from a Client.
@@ -190,7 +191,6 @@ func (q *Query) Query() error {
 	if handler == nil {
 		handler = DefaultQueryMux
 	}
-	//forever:
 	for {
 		select {
 		case in := <-q.QueryChan:
@@ -247,12 +247,14 @@ func (c *Client) ExchangeBuffer(inbuf []byte, a string, outbuf []byte) (n int, e
 	if c.Hijacked != nil {
 		w.conn = c.Hijacked
 	}
+	w.t = time.Now()
 	if n, err = w.writeClient(inbuf); err != nil {
 		return 0, err
 	}
 	if n, err = w.readClient(outbuf); err != nil {
 		return n, err
 	}
+	w.rtt = time.Since(w.t)
 	return n, nil
 }
 
@@ -297,22 +299,6 @@ func (w *reply) Dial() error {
 	return nil
 }
 
-func (w *reply) Close() (err error) {
-	return w.conn.Close()
-}
-
-func (w *reply) Client() *Client {
-	return w.client
-}
-
-func (w *reply) Request() *Msg {
-	return w.req
-}
-
-func (w *reply) TsigStatus() error {
-	return w.tsigStatus
-}
-
 func (w *reply) Receive() (*Msg, error) {
 	var p []byte
 	m := new(Msg)
@@ -323,13 +309,14 @@ func (w *reply) Receive() (*Msg, error) {
 		p = make([]byte, DefaultMsgSize)
 	}
 	n, err := w.readClient(p)
-	if err != nil {
+	if err != nil || n == 0 {
 		return nil, err
 	}
 	p = p[:n]
 	if ok := m.Unpack(p); !ok {
 		return nil, ErrUnpack
 	}
+	w.rtt = time.Since(w.t)
 	if m.IsTsig() {
 		secret := m.Extra[len(m.Extra)-1].(*RR_TSIG).Hdr.Name
 		if _, ok := w.Client().TsigSecret[secret]; !ok {
@@ -430,6 +417,7 @@ func (w *reply) Send(m *Msg) (err error) {
 			return ErrPack
 		}
 	}
+	w.t = time.Now()
 	if _, err = w.writeClient(out); err != nil {
 		return err
 	}
@@ -505,3 +493,18 @@ func (w *reply) writeClient(p []byte) (n int, err error) {
 	}
 	return
 }
+
+// Close implents the RequestWriter.Close method
+func (w *reply) Close() (err error) { return w.conn.Close() }
+
+// Client returns a pointer to the client
+func (w *reply) Client() *Client { return w.client }
+
+// Request returns the request contained in reply
+func (w *reply) Request() *Msg { return w.req }
+
+// TsigStatus implements the RequestWriter.TsigStatus method
+func (w *reply) TsigStatus() error { return w.tsigStatus }
+
+// Rtt implements the RequestWriter.Rtt method
+func (w *reply) Rtt() time.Duration { return w.rtt }

ex/q/q.go

@@ -27,6 +27,8 @@ 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
+	r.Rtt = w.Rtt()
 	w.Write(r)
 }
 
@@ -222,6 +224,8 @@ forever:
 				}
 
 				fmt.Printf("%v", r.Reply)
+				fmt.Printf("\n;; Query time: %.3d µs\n", r.Reply.Rtt/1e3)
+				// Server maybe
 			}
 			i++
 			if i == len(qname) {

msg.go

@@ -80,11 +80,12 @@ type MsgHdr struct {
 // The layout of a DNS message.
 type Msg struct {
 	MsgHdr
-	Compress bool       // If true, the message will be compressed when converted to wire format.
-	Question []Question // Holds the RR(s) of the question section.
-	Answer   []RR       // Holds the RR(s) of the answer section.
-	Ns       []RR       // Holds the RR(s) of the authority section.
-	Extra    []RR       // Holds the RR(s) of the additional section.
+	Compress   bool          // If true, the message will be compressed when converted to wire format.
+	Rtt        time.Duration // Round Trip Time, time it took between sending a reply and receiving the answer.
+	Question   []Question    // Holds the RR(s) of the question section.
+	Answer     []RR          // Holds the RR(s) of the answer section.
+	Ns         []RR          // Holds the RR(s) of the authority section.
+	Extra      []RR          // Holds the RR(s) of the additional section.
 }
 
 // Map of strings for each RR wire type.
@@ -373,7 +374,7 @@ func packStructValue(val reflect.Value, msg []byte, off int, compression map[str
 		case reflect.Slice:
 			switch val.Type().Field(i).Tag.Get("dns") {
 			default:
-				println("dns: unknown tag packing slice", val.Type().Field(i).Tag.Get("dns"), '"', val.Type().Field(i).Tag , '"')
+				println("dns: unknown tag packing slice", val.Type().Field(i).Tag.Get("dns"), '"', val.Type().Field(i).Tag, '"')
 				return lenmsg, false
 			case "domain-name":
 				for j := 0; j < val.Field(i).Len(); j++ {

server.go

@@ -23,7 +23,7 @@ type Handler interface {
 type ResponseWriter interface {
 	// RemoteAddr returns the net.Addr of the client that sent the current request.
 	RemoteAddr() net.Addr
-	// Return the status of the Tsig (TsigNone, TsigVerified or TsigBad)
+	// TsigSttus returns the status of the Tsig (TsigNone, TsigVerified or TsigBad).
 	TsigStatus() error
 	// Write writes a reply back to the client.
 	Write(*Msg) error
@@ -403,6 +403,4 @@ func (w *response) Write(m *Msg) (err error) {
 func (w *response) RemoteAddr() net.Addr { return w.conn.remoteAddr }
 
 // TsigStatus implements the ResponseWriter.TsigStatus method
-func (w *response) TsigStatus() error {
-	return w.tsigStatus
-}
+func (w *response) TsigStatus() error { return w.tsigStatus }