Rework the way NS are looked up

rs · Aug 15, 2018 · 4f4d9db · 4f4d9db
1 parent 3542d18
commit 4f4d9db
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Showing 3 changed files with 37 additions and 36 deletions.
diff --git a/client/cache.go b/client/cache.go
@@ -53,11 +53,11 @@ func (d *DelegationCache) Get(domain string) (label string, servers []Server) {
 	for offset, end := 0, false; !end; offset, end = dns.NextLabel(domain, offset) {
 		label = domain[offset:]
 		var found bool
-		if servers, found = d.c[label]; found {
-			return
+		if _, found = d.c[label]; found {
+			return label, append(servers, d.c[label]...)
 		}
 	}
-	return ".", roots
+	return ".", append(servers, roots...)
 }
 
 // Add adds a server as a delegation for domain. If addrs is not specified,

diff --git a/client/client.go b/client/client.go
@@ -52,8 +52,8 @@ func (rs Responses) Fastest() *Response {
 }
 
 type Tracer struct {
-	GotDelegateResponses func(i int, m *dns.Msg, rs Responses, rtype ResponseType)
-	FollowingCNAME       func(domain, target string)
+	GotIntermediaryResponse func(i int, m *dns.Msg, rs Responses, rtype ResponseType)
+	FollowingCNAME          func(domain, target string)
 }
 
 // New creates a new Client.
@@ -103,6 +103,26 @@ func (c *Client) RecursiveQuery(m *dns.Msg, tracer Tracer) (r *dns.Msg, rtt time
 	zone := "."
 	for i := 1; i < 100; i++ {
 		_, servers := c.DCache.Get(qname)
+
+		// Resolve servers name if needed.
+		wg := &sync.WaitGroup{}
+		for i, s := range servers {
+			if len(s.Addrs) == 0 {
+				wg.Add(1)
+				go func(s *Server) {
+					var err error
+					lm := m.Copy()
+					lm.SetQuestion(s.Name, 0) // qtypes are set by lookup host
+					s.Addrs, s.LookupRTT, err = c.lookupHost(lm)
+					if err != nil {
+						s.LookupErr = err
+					}
+					wg.Done()
+				}(&servers[i])
+			}
+		}
+		wg.Wait()
+
 		m.Question[0].Name = qname
 		rs := c.ParallelQuery(m, servers)
 
@@ -147,7 +167,6 @@ func (c *Client) RecursiveQuery(m *dns.Msg, tracer Tracer) (r *dns.Msg, rtt time
 		}
 
 		if rtype == ResponseTypeDelegation {
-			wg := &sync.WaitGroup{}
 			for _, ns := range r.Ns {
 				ns, ok := ns.(*dns.NS)
 				if !ok {
@@ -171,33 +190,17 @@ func (c *Client) RecursiveQuery(m *dns.Msg, tracer Tracer) (r *dns.Msg, rtt time
 					TTL:     ns.Header().Ttl,
 					Addrs:   addrs,
 				}
-				if !s.HasGlue {
-					wg.Add(1)
-					go func() {
-						var err error
-						lm := m.Copy()
-						lm.SetQuestion(s.Name, 0) // qtypes are set by lookup host
-						s.Addrs, s.LookupRTT, err = c.lookupHost(lm)
-						if err != nil {
-							s.LookupErr = err
-						}
-						c.DCache.Add(name, s)
-						wg.Done()
-					}()
-					continue
-				}
 				c.DCache.Add(name, s)
 				c.LCache.Set(s.Name, s.Addrs)
-				if tracer.GotDelegateResponses == nil {
-					// If not traced, do not resolve all NS
+				if tracer.GotIntermediaryResponse == nil {
+					// If not traced, only take first NS.
 					break
 				}
 			}
-			wg.Wait()
 		}
 
-		if tracer.GotDelegateResponses != nil {
-			tracer.GotDelegateResponses(i, m.Copy(), rs, rtype)
+		if tracer.GotIntermediaryResponse != nil {
+			tracer.GotIntermediaryResponse(i, m.Copy(), rs, rtype)
 		}
 
 		switch rtype {

diff --git a/main.go b/main.go
@@ -81,7 +81,7 @@ func main() {
 	c := client.New()
 	c.Client.Timeout = 500 * time.Millisecond
 	t := client.Tracer{
-		GotDelegateResponses: func(i int, m *dns.Msg, rs client.Responses, rtype client.ResponseType) {
+		GotIntermediaryResponse: func(i int, m *dns.Msg, rs client.Responses, rtype client.ResponseType) {
 			fr := rs.Fastest()
 			var r *dns.Msg
 			if fr != nil {
@@ -103,8 +103,13 @@ func main() {
 					ln = pr.Msg.Len()
 				}
 				rtt := float64(pr.RTT) / float64(time.Millisecond)
-				lrtt := float64(pr.Server.LookupRTT) / float64(time.Millisecond)
-				fmt.Printf(col("  - %3d bytes in %6.2fms + %6.2fms on %s(%s)", cDarkGray), ln, rtt, lrtt, pr.Addr, pr.Server.Name)
+				lrtt := "0ms (from cache)"
+				if pr.Server.HasGlue {
+					lrtt = "0ms (from glue)"
+				} else if pr.Server.LookupRTT > 0 {
+					lrtt = fmt.Sprintf("%.2fms", float64(pr.Server.LookupRTT)/float64(time.Millisecond))
+				}
+				fmt.Printf(col("  - %d bytes in %.2fms + %s lookup on %s(%s)", cDarkGray), ln, rtt, lrtt, pr.Server.Name, pr.Addr)
 				if pr.Err != nil {
 					err := pr.Err
 					if oerr, ok := err.(*net.OpError); ok {
@@ -130,13 +135,6 @@ func main() {
 						glue = col("glue: "+strings.Join(s.Addrs, ","), cDarkGray)
 					} else {
 						glue = col("no glue", cYellow)
-						if s.LookupErr != nil {
-							glue += fmt.Sprintf(col(": lookup err: %v", cDarkGray), col(s.LookupErr, cRed))
-						} else if s.LookupRTT == 0 {
-							glue += fmt.Sprintf(col(": lookup from cache", cDarkGray))
-						} else {
-							glue += fmt.Sprintf(col(": lookup time: %s", cDarkGray), s.LookupRTT)
-						}
 					}
 					fmt.Printf("%s %d NS %s (%s)\n", label, s.TTL, s.Name, glue)
 				}