panic: runtime error: index out of range [0] with length 0 #28
Comments
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Per stack trace, unbound is trying to write an invalid response without the question in it. |
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#25 Seems related |
It's the same mode of failure. Probably best to figure out why that happens in the first place in if len(res.AnswerPacket.Question) == 0 {
res.AnswerPacket.Question = r.Question
}Although it would be a safer hack to SERVFAIL when if err != nil || len(res.AnswerPacket.Question) == 0 {
return dns.RcodeServerFailure, err
} |
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Will you make a PR? I'm not good with golang. |
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do you have a test case? I think I can paper over it in miekg/unbound, but not sure if that is the best approach |
A papered over solution probably better to live here in the plugin - e.g. to return SERVFAIL if the AnswerPacket is missing a Question. |
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proper fix upstream with miekg/unbound#18. Thanks miekg! |
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Can the fix be applied in this repo since the upstream fix has stalled before being merged? It has been over a year, so I assume it won't be. |
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I think my issue might be related to this one since I'm getting same error message "[ERROR] Recovered from panic in server: "dns://:53" runtime error: index out of range [0] with length 0" with unbound plugin when I try to resolve IBM Cloud Kafka broker instance - broker-5-48d5s71514qnmqz3.kafka.svc11.us-south.eventstreams.cloud.ibm.com. Seems like it might be related to trying to resolve long sub-domains, but again not sure. When I was testing this 9/10 times it throws error message above and only once time it resolves and returns CNAME. |
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I echo the need for miekg/unbound#18 to be patched in this repo since upstream has stalled on merging in the fix. For others that are looking for a quick not ideal workaround you can manually patch the three line change with the following: Grab the patch from the PR: curl -sL -o pr18.patch https://patch-diff.githubusercontent.com/raw/miekg/unbound/pull/18.patchIf you are using a container to build a custom CoreDNS binary with this plugin you can apply it with the following: RUN go mod download
COPY plugin.cfg $GOPATH/src/github.com/coredns/coredns
RUN make gen
COPY pr18.patch /root/go/pkg/mod/github.com/miekg/unbound\@v0.0.0-20210309082708-dbeefb4cdb29
WORKDIR /root/go/pkg/mod/github.com/miekg/unbound\@v0.0.0-20210309082708-dbeefb4cdb29
RUN patch -p1 < pr18.patch
WORKDIR $GOPATH/src/github.com/coredns/corednsI have tested this with the latest CoreDNS 1.11.3 pre-release and it works as expected: $ podman exec coredns drill A 2.0.0.127.zen.spamhaus.org
;; ->>HEADER<<- opcode: QUERY, rcode: NOERROR, id: 51610
;; flags: qr rd ra ; QUERY: 1, ANSWER: 3, AUTHORITY: 0, ADDITIONAL: 0
;; QUESTION SECTION:
;; 2.0.0.127.zen.spamhaus.org. IN A
;; ANSWER SECTION:
2.0.0.127.zen.spamhaus.org. 60 IN A 127.0.0.4
2.0.0.127.zen.spamhaus.org. 60 IN A 127.0.0.2
2.0.0.127.zen.spamhaus.org. 60 IN A 127.0.0.10
;; AUTHORITY SECTION:
;; ADDITIONAL SECTION:
;; Query time: 392 msec
;; SERVER: 127.0.0.1
;; WHEN: Mon Jun 10 18:09:10 2024
;; MSG SIZE rcvd: 170 |
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I clicked a button |
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@miekg you are the best! Thanks dude! |
What happened:
Facing panic: runtime error: index out of range [0] with length 0
What you expected to happen:
No runtime panic.
How to reproduce it (as minimally and precisely as possible):
Do not know - happens periodically.
Anything else we need to know?:
Dockerfile:
Environment:
cat /etc/os-release):docker version:
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