Add fallback plugin (DNS endpoints only) #1398
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This fix adds a preliminary fallback plugin so that failed DNS queries could be sent to other endpoints. This fix only accept DNS endpoints at the moment. Signed-off-by: Yong Tang <yong.tang.github@outlook.com>
Codecov Report
@@ Coverage Diff @@
## master #1398 +/- ##
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- Coverage 51.51% 51.44% -0.08%
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Files 173 175 +2
Lines 8357 8421 +64
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+ Hits 4305 4332 +27
- Misses 3719 3753 +34
- Partials 333 336 +3
Continue to review full report at Codecov.
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| ~~~ corefile | ||
| . { | ||
| fallback example.org { | ||
| on NXDOMAIN 10.10.10.10:53 |
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maybe exemple with several failures cases - to show the full usage.
on NXDOMAIN
on SERVFAIL
on .. ???
is there a list of all events that can happen and we can use ?
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yes : SERVFAIL, NXDOMAIN, ERROR
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should NXDOMAIN be DENIAL ? or is there a NODATA ?
| } | ||
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| c = caddy.NewTestController("dns", `fallback example.org { | ||
| on NXDOMAIN 10.10.10.10:100 8.8.8.8:53 |
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test with several "on XXXX" ?
test with file (/etc/resolv.conf)
| state := request.Request{W: w, Req: r} | ||
| qname := state.Name() | ||
| log.Printf("[INFO] Send fallback %q to %q", qname, p.endpoint) | ||
| _, err := dns.Exchange(r, p.endpoint) |
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I understand we use directly Exchange as most of plugin are using Proxy.newLookup(...).
What I see is that in proxy (that is calling exchange), there is a management of the TTL of the query. We do not care here in case of error ?
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Knowing that this ErrorFunc can now be called whenever in the ServeDNS chain, including before any plugin is called, would it be safe to verify that the request is correctly defined ?
see in server.ServeDNS:
if r == nil || len(r.Question) == 0 {
DefaultErrorFunc(w, r, dns.RcodeServerFailure)
return
}
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I think there are some miscommunications there. Let's figure out what is the purpose of |
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I also initially though fallback was to send the failed query to some where else (thus no further handling). Now it looks like the purpose is to |
1. What does this pull request do?
This fix adds a preliminary fallback plugin so that failed DNS queries could be sent to other endpoints.
This fix only accept DNS endpoints at the moment.
2. Which issues (if any) are related?
This fix is part of the #1382.
3. Which documentation changes (if any) need to be made?
Signed-off-by: Yong Tang yong.tang.github@outlook.com