Added an option to only dump nameservers

go.mod

@@ -0,0 +1,8 @@
+module github.com/hakluke/dnstrace
+
+go 1.16
+
+require (
+	github.com/miekg/dns v1.1.43
+	github.com/rs/dnstrace v1.4.1
+)

go.sum

@@ -0,0 +1,14 @@
+github.com/miekg/dns v1.1.43 h1:JKfpVSCB84vrAmHzyrsxB5NAr5kLoMXZArPSw7Qlgyg=
+github.com/miekg/dns v1.1.43/go.mod h1:+evo5L0630/F6ca/Z9+GAqzhjGyn8/c+TBaOyfEl0V4=
+github.com/rs/dnstrace v1.4.1 h1:o6W+8hO9kGcdq9FZAVudpCyw6WXeD9XXamXyYiei/Hs=
+github.com/rs/dnstrace v1.4.1/go.mod h1:pFQiHK1kt94r2csi+qAxUsJ58r74QbN2q4JCDuFYTeY=
+golang.org/x/net v0.0.0-20210226172049-e18ecbb05110 h1:qWPm9rbaAMKs8Bq/9LRpbMqxWRVUAQwMI9fVrssnTfw=
+golang.org/x/net v0.0.0-20210226172049-e18ecbb05110/go.mod h1:m0MpNAwzfU5UDzcl9v0D8zg8gWTRqZa9RBIspLL5mdg=
+golang.org/x/sync v0.0.0-20210220032951-036812b2e83c h1:5KslGYwFpkhGh+Q16bwMP3cOontH8FOep7tGV86Y7SQ=
+golang.org/x/sync v0.0.0-20210220032951-036812b2e83c/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20210303074136-134d130e1a04 h1:cEhElsAv9LUt9ZUUocxzWe05oFLVd+AA2nstydTeI8g=
+golang.org/x/sys v0.0.0-20210303074136-134d130e1a04/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
+golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
+golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=

main.go

@@ -41,6 +41,7 @@ func init() {
 
 func main() {
 	color := flag.Bool("color", true, "Enable/disable colors")
+	nsonly := flag.Bool("nsonly", false, "Only print nameservers")
 	flag.Parse()
 
 	if flag.NArg() < 2 || flag.NArg() > 3 {
@@ -90,13 +91,21 @@ func main() {
 			qname := m.Question[0].Name
 			qtype := dns.TypeToString[m.Question[0].Qtype]
 			if i > 1 {
-				fmt.Println()
+				if !*nsonly {
+					fmt.Println()
+				}
+			}
+			if !*nsonly {
+				fmt.Printf("%d - query %s %s", i, qtype, qname)
 			}
-			fmt.Printf("%d - query %s %s", i, qtype, qname)
 			if r != nil {
-				fmt.Printf(": %s", strings.Replace(strings.Replace(r.MsgHdr.String(), ";; ", "", -1), "\n", ", ", -1))
+				if !*nsonly {
+					fmt.Printf(": %s", strings.Replace(strings.Replace(r.MsgHdr.String(), ";; ", "", -1), "\n", ", ", -1))
+				}
+			}
+			if !*nsonly {
+				fmt.Println()
 			}
-			fmt.Println()
 			for _, pr := range rs {
 				ln := 0
 				if pr.Msg != nil {
@@ -107,17 +116,25 @@ func main() {
 				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))
+					if !*nsonly {
+						lrtt = fmt.Sprintf("%.2fms", float64(pr.Server.LookupRTT)/float64(time.Millisecond))
+					}
+				}
+				if !*nsonly {
+					fmt.Printf(col("  - %d bytes in %.2fms + %s lookup on %s(%s)", cDarkGray), ln, rtt, lrtt, pr.Server.Name, pr.Addr)
 				}
-				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 {
 						err = oerr.Err
 					}
-					fmt.Printf(": %v", col(err, cRed))
+					if !*nsonly {
+						fmt.Printf(": %v", col(err, cRed))
+					}
+				}
+				if !*nsonly {
+					fmt.Print("\n")
 				}
-				fmt.Print("\n")
 			}
 
 			switch rtype {
@@ -133,15 +150,26 @@ func main() {
 				for _, s := range ns {
 					var glue string
 					if s.HasGlue {
-						glue = col("glue: "+strings.Join(s.Addrs, ","), cDarkGray)
+						if !*nsonly {
+							glue = col("glue: "+strings.Join(s.Addrs, ","), cDarkGray)
+						}
+					} else {
+						if !*nsonly {
+							glue = col("no glue", cYellow)
+						}
+					}
+					if !*nsonly {
+						fmt.Printf("%s %d NS %s (%s)\n", label, s.TTL, s.Name, glue)
 					} else {
-						glue = col("no glue", cYellow)
+						// just print the nameserver hostname without any details
+						fmt.Printf("%s\n", s.Name)
 					}
-					fmt.Printf("%s %d NS %s (%s)\n", label, s.TTL, s.Name, glue)
 				}
 			case client.ResponseTypeCNAME:
 				for _, rr := range r.Answer {
-					fmt.Println(rr)
+					if !*nsonly {
+						fmt.Println(rr)
+					}
 				}
 			}
 		},
@@ -154,10 +182,13 @@ func main() {
 		fmt.Printf(col("*** error: %v\n", cRed), err)
 		os.Exit(1)
 	}
-
-	fmt.Println()
-	fmt.Printf(col(";; Cold best path time: %s\n\n", cGray), rtt)
+	if !*nsonly {
+		fmt.Println()
+		fmt.Printf(col(";; Cold best path time: %s\n\n", cGray), rtt)
+	}
 	for _, rr := range r.Answer {
-		fmt.Println(rr)
+		if !*nsonly {
+			fmt.Println(rr)
+		}
 	}
 }