jinrenjie
commented
1 month ago I think the problem might be here:
func (d *DNSServer) answer(q dns.Question) ([]dns.RR, int, bool, error) {
var rcode int
var err error
var txtRRs []dns.RR
var authoritative = d.isAuthoritative(q)
if !d.isOwnChallenge(q.Name) && !d.answeringForDomain(q.Name) {
rcode = dns.RcodeNameError
}
r, _ := d.getRecord(q)
+ for _, rr := range r {
+ if rr.Header().Rrtype == dns.TypeCNAME && len(r) == 1 {
+ q = dns.Question{
+ Name: rr.(*dns.CNAME).Target,
+ Qtype: q.Qtype,
+ Qclass: q.Qclass,
+ }
+ }
+ }
if q.Qtype == dns.TypeTXT {
if d.isOwnChallenge(q.Name) {
txtRRs, err = d.answerOwnChallenge(q)
} else {
txtRRs, err = d.answerTXT(q)
}
if err == nil {
r = append(r, txtRRs...)
}
}
if len(r) > 0 {
// Make sure that we return NOERROR if there were dynamic records for the domain
rcode = dns.RcodeSuccess
}
log.WithFields(log.Fields{"qtype": dns.TypeToString[q.Qtype], "domain": q.Name, "rcode": dns.RcodeToString[rcode]}).Debug("Answering question for domain")
return r, rcode, authoritative, nil
}When there is only one CNAME record obtained from DNS, use the value of the CNAME record as the parameter of d.answerTXT() to obtain the TXT record in the database.
Once I did this, Smallstep CA Server was able to verify and issue certificates just fine!
I don't know if this is a common practice, But I can traverse and query the TXT records on the CNAME in the cloud service provider's DNS like this:
dig TXT _acme-challenge.betterde.com @223.5.5.5
; <<>> DiG 9.10.6 <<>> TXT _acme-challenge.betterde.com @223.5.5.5
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 59316
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 1
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1408
;; QUESTION SECTION:
;_acme-challenge.betterde.com. IN TXT
;; ANSWER SECTION:
_acme-challenge.betterde.com. 600 IN CNAME 1ef56a0d-5f76-4aae-93ca-d3209823a217.betterde.com.
1ef56a0d-5f76-4aae-93ca-d3209823a217.betterde.com. 600 IN TXT "L6gnTrq24MA66xjFQ0jvAFhtia83cxu2zJBtPdMB6UH"
;; Query time: 200 msec
;; SERVER: 223.5.5.5#53(223.5.5.5)
;; WHEN: Tue Jul 16 03:13:24 CST 2024
;; MSG SIZE rcvd: 164
TRPB
Architecture
These services all run in containers and can communicate with each other.
acme-dns.cfgis configured as follows:Get acme-dns account fulldomain TXT records:
This seems to be all working fine!
Get the NS record of
ingress.test:Get the TXT record of
_acme-challenge.ingress.test:There seems to be a problem here. In theory, both the CNAME and TXT records should be queried at the same time, but no TXT record appears. As a result, the Smallstep CA I use cannot verify the DNS challenge and cannot issue a certificate!
This problem has troubled me for a long time and I have not found a solution. I look forward to your answer, which will be of great help to me. Thank you!