// perform a DNS query and assert the reply code, number or answers, etc
func assertExchange(t *testing.T, z string, ty uint16, minAnswers int, maxAnswers int, expErr int) *dns.Msg {
c := new(dns.Client)
c.UDPSize = testUDPBufSize
m := new(dns.Msg)
m.RecursionDesired = true
m.SetQuestion(z, ty)
m.SetEdns0(testUDPBufSize, false) // we don't want to play with truncation here...
r, _, err := c.Exchange(m, fmt.Sprintf("127.0.0.1:%d", testPort))
t.Logf("Response:\n%+v\n", r)
wt.AssertNoErr(t, err)
if minAnswers == 0 && maxAnswers == 0 {
wt.AssertStatus(t, r.Rcode, expErr, "DNS response code")
} else {
wt.AssertStatus(t, r.Rcode, dns.RcodeSuccess, "DNS response code")
}
answers := len(r.Answer)
if minAnswers >= 0 && answers < minAnswers {
wt.Fatalf(t, "Number of answers >= %d", minAnswers)
}
if maxAnswers >= 0 && answers > maxAnswers {
wt.Fatalf(t, "Number of answers <= %d", maxAnswers)
}
return r
}
func TestTCPDNSServer(t *testing.T) {
setupForTest(t)
const (
numAnswers = 512
nonLocalName = "weave.works."
)
InitDefaultLogging(testing.Verbose())
Info.Println("TestTCPDNSServer starting")
zone, err := NewZoneDb(ZoneConfig{})
require.NoError(t, err)
err = zone.Start()
require.NoError(t, err)
defer zone.Stop()
// generate a list of `numAnswers` IP addresses
var addrs []ZoneRecord
bs := make([]byte, 4)
for i := 0; i < numAnswers; i++ {
binary.LittleEndian.PutUint32(bs, uint32(i))
ip := net.IPv4(bs[0], bs[1], bs[2], bs[3])
addrs = append(addrs, ZoneRecord(Record{"", ip, 0, 0, 0}))
}
// handler for the fallback server: it will just return a very long response
fallbackUDPHandler := func(w dns.ResponseWriter, req *dns.Msg) {
if len(req.Question) == 0 {
return // ignore empty queries (sent when shutting down the server)
}
maxLen := getMaxReplyLen(req, protUDP)
t.Logf("Fallback UDP server got asked: returning %d answers", numAnswers)
q := req.Question[0]
m := makeAddressReply(req, &q, addrs, DefaultLocalTTL)
mLen := m.Len()
m.SetEdns0(uint16(maxLen), false)
if mLen > maxLen {
t.Logf("... truncated response (%d > %d)", mLen, maxLen)
m.Truncated = true
}
w.WriteMsg(m)
}
fallbackTCPHandler := func(w dns.ResponseWriter, req *dns.Msg) {
if len(req.Question) == 0 {
return // ignore empty queries (sent when shutting down the server)
}
t.Logf("Fallback TCP server got asked: returning %d answers", numAnswers)
q := req.Question[0]
m := makeAddressReply(req, &q, addrs, DefaultLocalTTL)
w.WriteMsg(m)
}
t.Logf("Running a DNS fallback server with UDP")
fallback, err := newMockedFallback(fallbackUDPHandler, fallbackTCPHandler)
require.NoError(t, err)
fallback.Start()
defer fallback.Stop()
t.Logf("Creating a WeaveDNS server instance, falling back to 127.0.0.1:%d", fallback.Port)
srv, err := NewDNSServer(DNSServerConfig{
Zone: zone,
UpstreamCfg: fallback.CliConfig,
CacheDisabled: true,
ListenReadTimeout: testSocketTimeout,
})
require.NoError(t, err)
err = srv.Start()
require.NoError(t, err)
go srv.ActivateAndServe()
defer srv.Stop()
time.Sleep(100 * time.Millisecond) // Allow sever goroutine to start
testPort, err := srv.GetPort()
require.NoError(t, err)
require.NotEqual(t, 0, testPort, "listen port")
dnsAddr := fmt.Sprintf("127.0.0.1:%d", testPort)
t.Logf("Creating a UDP and a TCP client")
uc := new(dns.Client)
uc.UDPSize = minUDPSize
tc := new(dns.Client)
tc.Net = "tcp"
t.Logf("Creating DNS query message")
m := new(dns.Msg)
m.RecursionDesired = true
m.SetQuestion(nonLocalName, dns.TypeA)
t.Logf("Checking the fallback server at %s returns a truncated response with UDP", fallback.Addr)
r, _, err := uc.Exchange(m, fallback.Addr)
t.Logf("Got response from fallback server (UDP) with %d answers", len(r.Answer))
t.Logf("Response:\n%+v\n", r)
require.NoError(t, err)
require.True(t, r.MsgHdr.Truncated, "DNS truncated reponse flag")
require.NotEqual(t, numAnswers, len(r.Answer), "number of answers (UDP)")
t.Logf("Checking the WeaveDNS server at %s returns a truncated reponse with UDP", dnsAddr)
r, _, err = uc.Exchange(m, dnsAddr)
t.Logf("UDP Response:\n%+v\n", r)
require.NoError(t, err)
require.NotNil(t, r, "response")
t.Logf("%d answers", len(r.Answer))
require.True(t, r.MsgHdr.Truncated, "DNS truncated reponse flag")
require.NotEqual(t, numAnswers, len(r.Answer), "number of answers (UDP)")
t.Logf("Checking the WeaveDNS server at %s does not return a truncated reponse with TCP", dnsAddr)
r, _, err = tc.Exchange(m, dnsAddr)
t.Logf("TCP Response:\n%+v\n", r)
require.NoError(t, err)
require.NotNil(t, r, "response")
t.Logf("%d answers", len(r.Answer))
require.False(t, r.MsgHdr.Truncated, "DNS truncated response flag")
require.Equal(t, numAnswers, len(r.Answer), "number of answers (TCP)")
t.Logf("Checking the WeaveDNS server at %s does not return a truncated reponse with UDP with a bigger buffer", dnsAddr)
m.SetEdns0(testUDPBufSize, false)
r, _, err = uc.Exchange(m, dnsAddr)
t.Logf("UDP-large Response:\n%+v\n", r)
require.NoError(t, err)
require.NotNil(t, r, "response")
t.Logf("%d answers", len(r.Answer))
require.NoError(t, err)
require.False(t, r.MsgHdr.Truncated, "DNS truncated response flag")
require.Equal(t, numAnswers, len(r.Answer), "number of answers (UDP-long)")
}
func TestTCPDNSServer(t *testing.T) {
setupForTest(t)
const (
numAnswers = 512
nonLocalName = "weave.works."
)
dnsAddr := fmt.Sprintf("localhost:%d", testPort)
InitDefaultLogging(true)
var zone = NewZoneDb(DefaultLocalDomain)
// generate a list of `numAnswers` IP addresses
var addrs []ZoneRecord
bs := make([]byte, 4)
for i := 0; i < numAnswers; i++ {
binary.LittleEndian.PutUint32(bs, uint32(i))
addrs = append(addrs, Record{"", net.IPv4(bs[0], bs[1], bs[2], bs[3]), 0, 0, 0})
}
// handler for the fallback server: it will just return a very long response
fallbackUDPHandler := func(w dns.ResponseWriter, req *dns.Msg) {
maxLen := getMaxReplyLen(req, protUDP)
t.Logf("Fallback UDP server got asked: returning %d answers", numAnswers)
q := req.Question[0]
m := makeAddressReply(req, &q, addrs)
mLen := m.Len()
m.SetEdns0(uint16(maxLen), false)
if mLen > maxLen {
t.Logf("... truncated response (%d > %d)", mLen, maxLen)
m.Truncated = true
}
w.WriteMsg(m)
}
fallbackTCPHandler := func(w dns.ResponseWriter, req *dns.Msg) {
t.Logf("Fallback TCP server got asked: returning %d answers", numAnswers)
q := req.Question[0]
m := makeAddressReply(req, &q, addrs)
w.WriteMsg(m)
}
t.Logf("Running a DNS fallback server with UDP")
us, fallbackUDPAddr, err := runLocalUDPServer(t, "127.0.0.1:0", fallbackUDPHandler)
wt.AssertNoErr(t, err)
defer us.Shutdown()
_, fallbackPort, err := net.SplitHostPort(fallbackUDPAddr)
wt.AssertNoErr(t, err)
t.Logf("Starting another fallback server, with TCP, on the same port as the UDP server")
fallbackTCPAddr := fmt.Sprintf("127.0.0.1:%s", fallbackPort)
ts, fallbackTCPAddr, err := runLocalTCPServer(t, fallbackTCPAddr, fallbackTCPHandler)
wt.AssertNoErr(t, err)
defer ts.Shutdown()
t.Logf("Creating a WeaveDNS server instance, falling back to 127.0.0.1:%s", fallbackPort)
config := &dns.ClientConfig{Servers: []string{"127.0.0.1"}, Port: fallbackPort}
srv, err := NewDNSServer(DNSServerConfig{UpstreamCfg: config, Port: testPort}, zone, nil)
wt.AssertNoErr(t, err)
defer srv.Stop()
go srv.Start()
time.Sleep(100 * time.Millisecond) // Allow sever goroutine to start
t.Logf("Creating a UDP and a TCP client")
uc := new(dns.Client)
uc.UDPSize = minUDPSize
tc := new(dns.Client)
tc.Net = "tcp"
t.Logf("Creating DNS query message")
m := new(dns.Msg)
m.RecursionDesired = true
m.SetQuestion(nonLocalName, dns.TypeA)
t.Logf("Checking the fallback server at %s returns a truncated response with UDP", fallbackUDPAddr)
r, _, err := uc.Exchange(m, fallbackUDPAddr)
t.Logf("Got response from fallback server (UDP) with %d answers", len(r.Answer))
t.Logf("Response:\n%+v\n", r)
wt.AssertNoErr(t, err)
wt.AssertTrue(t, r.MsgHdr.Truncated, "DNS truncated reponse flag")
wt.AssertNotEqualInt(t, len(r.Answer), numAnswers, "number of answers (UDP)")
t.Logf("Checking the WeaveDNS server at %s returns a truncated reponse with UDP", dnsAddr)
r, _, err = uc.Exchange(m, dnsAddr)
t.Logf("UDP Response:\n%+v\n", r)
wt.AssertNoErr(t, err)
wt.AssertNotNil(t, r, "response")
t.Logf("%d answers", len(r.Answer))
wt.AssertTrue(t, r.MsgHdr.Truncated, "DNS truncated reponse flag")
wt.AssertNotEqualInt(t, len(r.Answer), numAnswers, "number of answers (UDP)")
t.Logf("Checking the WeaveDNS server at %s does not return a truncated reponse with TCP", dnsAddr)
r, _, err = tc.Exchange(m, dnsAddr)
t.Logf("TCP Response:\n%+v\n", r)
wt.AssertNoErr(t, err)
wt.AssertNotNil(t, r, "response")
t.Logf("%d answers", len(r.Answer))
wt.AssertFalse(t, r.MsgHdr.Truncated, "DNS truncated response flag")
wt.AssertEqualInt(t, len(r.Answer), numAnswers, "number of answers (TCP)")
t.Logf("Checking the WeaveDNS server at %s does not return a truncated reponse with UDP with a bigger buffer", dnsAddr)
m.SetEdns0(testUDPBufSize, false)
r, _, err = uc.Exchange(m, dnsAddr)
t.Logf("UDP-large Response:\n%+v\n", r)
wt.AssertNoErr(t, err)
wt.AssertNotNil(t, r, "response")
t.Logf("%d answers", len(r.Answer))
wt.AssertNoErr(t, err)
wt.AssertFalse(t, r.MsgHdr.Truncated, "DNS truncated response flag")
wt.AssertEqualInt(t, len(r.Answer), numAnswers, "number of answers (UDP-long)")
}