1 package dns
2 
3 import (
4 	"math/rand"
5 	"net"
6 	"testing"
7 
8 	"golang.org/x/net/dns/dnsmessage"
9 )
10 
11 var testq = dnsmessage.Question{Name: dnsmessage.MustNewName("www.example.com."), Type: dnsmessage.TypeA, Class: dnsmessage.ClassINET}
12 
13 func resolveBadly(w ResponseWriter, qmsg *dnsmessage.Message) {
14 	rmsg := dnsmessage.Message{
15 		Header: dnsmessage.Header{
16 			ID:       qmsg.Header.ID + 69,
17 			Response: false,
18 			RCode:    dnsmessage.RCodeNameError,
19 		},
20 		Questions: qmsg.Questions,
21 	}
22 	w.WriteMsg(rmsg)
23 }
24 
25 func resolveWrongQuestion(w ResponseWriter, qmsg *dnsmessage.Message) {
26 	wrongq := dnsmessage.Question{Name: dnsmessage.MustNewName("blabla.example.org."), Type: dnsmessage.TypeNS, Class: dnsmessage.ClassCHAOS}
27 	rmsg := dnsmessage.Message{
28 		Header: dnsmessage.Header{
29 			ID:            qmsg.Header.ID,
30 			Response:      true,
31 			RCode:         dnsmessage.RCodeSuccess,
32 			Authoritative: true,
33 		},
34 		Questions: []dnsmessage.Question{wrongq},
35 	}
36 	w.WriteMsg(rmsg)
37 }
38 
39 func TestBadResolver(t *testing.T) {
40 	srv := Server{network: "udp", addr: "127.0.0.1", Handler: resolveBadly}
41 	conn, err := net.ListenPacket("udp", "127.0.0.1:5359")
42 	if err != nil {
43 		t.Fatal(err)
44 	}
45 	go func() {
46 		t.Fatal(srv.ServePacket(conn))
47 	}()
48 	rmsg, err := Ask(testq, "127.0.0.1:5359")
49 	if err == nil {
50 		t.Error("wanted error, got nil")
51 	}
52 	t.Log(err)
53 	t.Log("sent:", testq, "received", rmsg)
54 
55 	srv.Handler = resolveWrongQuestion
56 	rmsg, err = Ask(testq, "127.0.0.1:5359")
57 	if err == nil {
58 		t.Error("wanted error, got nil")
59 	} else if err != nil {
60 		t.Log(err)
61 	}
62 	t.Log("sent:", testq, "received:", rmsg)
63 }
64 
65 func buildmsg(s string) (dnsmessage.Message, error) {
66 	name, err := dnsmessage.NewName(s)
67 	if err != nil {
68 		return dnsmessage.Message{}, err
69 	}
70 	var msg dnsmessage.Message
71 	header := dnsmessage.Header{ID: uint16(rand.Intn(8192)), RecursionDesired: true}
72 	buf := make([]byte, 2, 512+2)
73 	b := dnsmessage.NewBuilder(buf, header)
74 	b.EnableCompression()
75 	q := dnsmessage.Question{Name: name, Type: dnsmessage.TypeA, Class: dnsmessage.ClassINET}
76 	if err := b.StartQuestions(); err != nil {
77 		return msg, err
78 	}
79 	if err := b.Question(q); err != nil {
80 		return msg, err
81 	}
82 	packed, err := b.Finish()
83 	if err != nil {
84 		return msg, err
85 	}
86 	if err := msg.Unpack(packed[2:]); err != nil {
87 		return msg, err
88 	}
89 	return msg, nil
90 }