-
Notifications
You must be signed in to change notification settings - Fork 3
/
check-soa.go
434 lines (423 loc) · 11.8 KB
/
check-soa.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
// A simple program to have rapidly an idea of the health of a DNS
// zone. It queries each name server of the zone for the SOA record and
// displays the value of the serial number for each server.
//
// Stephane Bortzmeyer <bortzmeyer@nic.fr>
package main
import (
"errors"
"flag"
"fmt"
"github.com/miekg/dns"
"net"
"os"
"sort"
"time"
)
const (
TIMEOUT float64 = float64(1.5)
MAXTRIALS uint = 3
MAX_NAMESERVERS uint = 20
MAX_ADDRESSES uint = 10
EDNSBUFFERSIZE uint16 = 4096
)
var (
/* TODO: make it per-thread? It does not seem necessary, the goroutines
do not modify it */
conf *dns.ClientConfig
v4only *bool
v6only *bool
debug *bool
quiet *bool
noedns *bool
times *bool
timeout time.Duration
maxTrials *int
)
type DNSreply struct {
qname string
qtype uint16
r *dns.Msg
err error
nameserver string
rtt time.Duration
}
type SOAreply struct {
name string
address string
serial uint32
retrieved bool
msg string
rtt time.Duration
}
type nameServer struct {
name string
ips []string
globalErrMsg string
success []bool
errMsg []string
serial []uint32
rtts []time.Duration
}
type Results map[string]nameServer
func localQuery(mychan chan DNSreply, qname string, qtype uint16) {
var result DNSreply
var trials uint
result.qname = qname
result.qtype = qtype
result.r = nil
result.err = errors.New("No name server to answer the question")
localm := new(dns.Msg)
localm.MsgHdr.RecursionDesired = true
localm.Question = make([]dns.Question, 1)
localc := new(dns.Client)
localc.ReadTimeout = timeout
localm.Question[0] = dns.Question{qname, qtype, dns.ClassINET}
Tests:
for trials = 0; trials < uint(*maxTrials); trials++ {
Resolvers:
for serverIndex := range conf.Servers {
server := conf.Servers[serverIndex]
result.nameserver = server
r, rtt, err := localc.Exchange(localm, server+":"+conf.Port) // Do not use net.JoinHostPort, see https://github.com/bortzmeyer/check-soa/commit/3e4edb13855d8c4016768796b2892aa83eda1933#commitcomment-2355543
if r == nil {
result.r = nil
result.err = err
if err.(net.Error).Timeout() {
// Try another resolver
break Resolvers
} else { // We give in
break Tests
}
} else {
result.rtt = rtt
if r.Rcode == dns.RcodeSuccess {
// TODO: for rcodes like SERVFAIL, trying another resolver could make sense
result.r = r
result.err = nil
break Tests
} else {
// All the other codes are errors. Yes, it may
// happens that one resolver returns REFUSED
// and the others work but we do not handle
// this case. TODO: delete the resolver from
// the list and try another one
result.r = r
result.err = errors.New(dns.RcodeToString[r.Rcode])
break Tests
}
}
}
}
if *debug {
fmt.Printf("DEBUG: end of request %s %d\n", qname, qtype)
}
mychan <- result
}
func soaQuery(mychan chan SOAreply, zone string, name string, server string) {
var result SOAreply
var trials uint
result.retrieved = false
result.name = name
result.address = server
result.msg = "UNKNOWN"
m := new(dns.Msg)
// TODO: allow option DNSSEC DO (to detect firewall or fragmentation problems)
if !*noedns {
m.SetEdns0(EDNSBUFFERSIZE, true)
}
m.MsgHdr.RecursionDesired = false
m.Question = make([]dns.Question, 1)
c := new(dns.Client)
c.ReadTimeout = timeout
m.Question[0] = dns.Question{zone, dns.TypeSOA, dns.ClassINET}
nsAddressPort := ""
nsAddressPort = net.JoinHostPort(server, "53")
if *debug {
fmt.Printf("DEBUG Querying SOA from %s\n", nsAddressPort)
}
for trials = 0; trials < uint(*maxTrials); trials++ {
soa, rtt, err := c.Exchange(m, nsAddressPort)
if soa == nil {
result.rtt = 0
if !err.(net.Error).Timeout() {
result.msg = fmt.Sprintf("%s", err)
break
} else {
result.msg = fmt.Sprintf("Timeout")
}
} else {
result.rtt = rtt
if soa.Rcode != dns.RcodeSuccess {
result.msg = dns.RcodeToString[soa.Rcode]
break
} else {
if len(soa.Answer) == 0 { /* May happen if the server is a recursor, not authoritative, since we query with RD=0 */
result.msg = "0 answer"
break
} else {
rsoa := soa.Answer[0]
switch rsoa.(type) {
case *dns.SOA:
if soa.MsgHdr.Authoritative {
result.retrieved = true
result.serial = rsoa.(*dns.SOA).Serial
result.msg = "OK"
} else {
result.msg = "Not authoritative"
}
default:
// TODO: a name server can send us other RR types.
fmt.Printf("Internal error when processing %s\n", rsoa)
os.Exit(1)
}
break
}
}
}
}
mychan <- result
}
func masterTask(zone string, nameserverRecords []dns.RR) (uint, uint, bool, Results) {
var (
numRequests uint
)
success := true
addressChannel := make(chan DNSreply)
soaChannel := make(chan SOAreply)
numNS := uint(0)
numAddrNS := uint(0)
nameservers := make(map[string]nameServer)
results := make(Results)
for i := range nameserverRecords {
ans := nameserverRecords[i]
switch ans.(type) {
case *dns.NS:
name := ans.(*dns.NS).Ns
nameservers[name] = nameServer{name: name, ips: make([]string, MAX_ADDRESSES)}
if !*v6only {
go localQuery(addressChannel, name, dns.TypeA)
}
if !*v4only {
go localQuery(addressChannel, name, dns.TypeAAAA)
}
numNS += 1
}
}
if *v6only || *v4only {
numRequests = numNS
} else {
numRequests = numNS * 2
}
for i := uint(0); i < numRequests; i++ {
addrResult := <-addressChannel
addrFamily := "IPv6"
if addrResult.qtype == dns.TypeA {
addrFamily = "IPv4"
}
if addrResult.r == nil {
// TODO We may have different globalErrMsg is it
// works with IPv4 but not IPv6 (it should not happen but it does)
nameservers[addrResult.qname] = nameServer{
name: addrResult.qname,
ips: nil,
globalErrMsg: fmt.Sprintf("Cannot get the %s address: %s", addrFamily, addrResult.err)}
success = false
} else {
if addrResult.r.Rcode != dns.RcodeSuccess {
nameservers[addrResult.qname] = nameServer{
name: addrResult.qname,
ips: nil,
globalErrMsg: fmt.Sprintf("Cannot get the %s address: %s", addrFamily, dns.RcodeToString[addrResult.r.Rcode])}
success = false
} else {
for j := range addrResult.r.Answer {
ansa := addrResult.r.Answer[j]
var ns string
switch ansa.(type) {
case *dns.A:
ns = ansa.(*dns.A).A.String()
nameservers[addrResult.qname] = nameServer{name: addrResult.qname, ips: append(nameservers[addrResult.qname].ips, ns)}
numAddrNS += 1
go soaQuery(soaChannel, zone, addrResult.qname, ns)
case *dns.AAAA:
ns = ansa.(*dns.AAAA).AAAA.String()
nameservers[addrResult.qname] = nameServer{name: addrResult.qname, ips: append(nameservers[addrResult.qname].ips, ns)}
numAddrNS += 1
go soaQuery(soaChannel, zone, addrResult.qname, ns)
}
}
}
}
}
for i := uint(0); i < numAddrNS; i++ {
if *debug {
fmt.Printf("DEBUG Getting result for ns #%d/%d\n", i+1, numAddrNS)
}
soaResult := <-soaChannel
_, present := results[soaResult.name]
if !present {
results[soaResult.name] = nameServer{name: soaResult.name,
ips: make([]string, 0),
success: make([]bool, 0),
errMsg: make([]string, 0),
serial: make([]uint32, 0),
rtts: make([]time.Duration, 0)}
}
if !soaResult.retrieved {
results[soaResult.name] = nameServer{name: soaResult.name,
ips: append(results[soaResult.name].ips, soaResult.address),
success: append(results[soaResult.name].success, false),
errMsg: append(results[soaResult.name].errMsg, fmt.Sprintf("%s", soaResult.msg)),
serial: append(results[soaResult.name].serial, 0),
rtts: append(results[soaResult.name].rtts, soaResult.rtt)}
success = false
} else {
results[soaResult.name] = nameServer{name: soaResult.name,
ips: append(results[soaResult.name].ips, soaResult.address),
success: append(results[soaResult.name].success, true),
errMsg: append(results[soaResult.name].errMsg, ""),
serial: append(results[soaResult.name].serial, soaResult.serial),
rtts: append(results[soaResult.name].rtts, soaResult.rtt)}
}
}
for name := range nameservers {
if nameservers[name].ips == nil {
results[name] = nameservers[name]
}
}
return numNS, numAddrNS, success, results
}
func main() {
var (
err error
)
flag.Usage = func() {
fmt.Fprintf(os.Stderr, "Usage of %s:\n", os.Args[0])
fmt.Fprintf(os.Stderr, "%s [options] ZONE\n", os.Args[0])
flag.PrintDefaults()
}
v4only = flag.Bool("4", false, "Use only IPv4")
v6only = flag.Bool("6", false, "Use only IPv6")
help := flag.Bool("h", false, "Print help")
debug = flag.Bool("d", false, "Debugging")
quiet = flag.Bool("q", false, "Quiet mode, display only errors")
noedns = flag.Bool("r", false, "Disable EDNS format")
times = flag.Bool("i", false, "Display the response time of servers")
timeoutI := flag.Float64("t", float64(TIMEOUT), "Timeout in seconds")
maxTrials = flag.Int("n", int(MAXTRIALS), "Number of trials before giving in")
flag.Parse()
if *debug && *quiet {
fmt.Fprintf(os.Stderr, "debug or quiet but not both\n")
flag.Usage()
os.Exit(1)
}
if *v4only && *v6only {
fmt.Fprintf(os.Stderr, "v4-only or v6-only but not both\n")
flag.Usage()
os.Exit(1)
}
if len(flag.Args()) != 1 {
fmt.Fprintf(os.Stderr, "Only one argument expected, %d arguments received\n", len(flag.Args()))
flag.Usage()
os.Exit(1)
}
if *timeoutI <= 0 {
fmt.Fprintf(os.Stderr, "Timeout must be positive, not %d\n", *timeoutI)
flag.Usage()
os.Exit(1)
}
timeout = time.Duration(*timeoutI * float64(time.Second))
if *maxTrials <= 0 {
fmt.Fprintf(os.Stderr, "Number of trials must be positive, not %d\n", *maxTrials)
flag.Usage()
os.Exit(1)
}
if *help {
flag.Usage()
os.Exit(0)
}
zone := dns.Fqdn(flag.Arg(0))
conf, err = dns.ClientConfigFromFile("/etc/resolv.conf")
if conf == nil {
fmt.Printf("Cannot initialize the local resolver: %s\n", err)
os.Exit(1)
}
nsChan := make(chan DNSreply)
go localQuery(nsChan, zone, dns.TypeNS)
nsResult := <-nsChan
if nsResult.r == nil {
fmt.Printf("Cannot retrieve the list of name servers for %s: %s\n", zone, nsResult.err)
os.Exit(1)
}
if nsResult.r.Rcode == dns.RcodeNameError {
fmt.Printf("No such domain %s\n", zone)
os.Exit(1)
}
numNS, numNSaddr, success, results := masterTask(zone, nsResult.r.Answer)
if numNS == 0 {
fmt.Printf("No NS records for \"%s\". It is probably a domain but not a zone\n", zone)
os.Exit(1)
}
if numNSaddr == 0 {
fmt.Printf("No IP addresses for name servers of %s\n", zone)
if *v4only {
fmt.Printf("May be retry without -4?\n")
}
if *v6only {
fmt.Printf("May be retry without -6?\n")
}
os.Exit(1)
}
/* TODO: test if all name servers have the same serial ? */
keys := make([]string, len(results))
i := 0
for k, _ := range results {
keys[i] = k
i++
}
// TODO: allow to sort by response time?
sort.Strings(keys)
for k := range keys {
serverOK := true
result := results[keys[k]]
for i := 0; i < len(result.ips); i++ {
if !result.success[i] {
serverOK = false
break
}
if result.ips == nil {
serverOK = false
break
}
}
if !*quiet || !serverOK {
fmt.Printf("%s\n", keys[k])
}
for i := 0; i < len(result.ips); i++ {
code := "ERROR"
msg := ""
if result.success[i] {
code = "OK"
msg = fmt.Sprintf("%d", result.serial[i])
} else {
msg = result.errMsg[i]
}
if *times && result.rtts[i] != 0 {
msg = msg + fmt.Sprintf(" (%d ms)", int(float64(result.rtts[i])/1e6))
}
if !*quiet || !result.success[i] {
fmt.Printf("\t%s: %s: %s\n", result.ips[i], code, msg)
}
}
if len(result.ips) == 0 {
success = false
fmt.Printf("\t%s\n", result.globalErrMsg)
}
}
if success {
os.Exit(0)
} else {
os.Exit(1)
}
}