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Fix dns-01-003 (#1634)

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* plugin/{cache,forward,proxy}: don't allow responses that are bogus

Responses that are not matching what we've been querying for should be
dropped. They are converted into FormErrs by forward and proxy; as a 2nd
backstop cache will also not cache these.

* plug

* add explicit test
This commit is contained in:
Miek Gieben 2018-03-25 17:11:10 +01:00 • committed by GitHub
parent 91413c25e1
commit 5616fcb175
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GPG key ID: 4AEE18F83AFDEB23
7 changed files with 102 additions and 5 deletions
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11
plugin/cache/handler.go vendored
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@ -46,7 +46,7 @@ func (c *Cache) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg)
// When prefetching we loose the item i, and with it the frequency
// that we've gathered sofar. See we copy the frequencies info back
// into the new item that was stored in the cache.
prr := &ResponseWriter{ResponseWriter: w, Cache: c, prefetch: true}
prr := &ResponseWriter{ResponseWriter: w, Cache: c, prefetch: true, state: state}
plugin.NextOrFailure(c.Name(), c.Next, ctx, prr, r)
if i1 := c.exists(qname, qtype, do); i1 != nil {
@ -58,7 +58,7 @@ func (c *Cache) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg)
return dns.RcodeSuccess, nil
}
crr := &ResponseWriter{ResponseWriter: w, Cache: c}
crr := &ResponseWriter{ResponseWriter: w, Cache: c, state: state}
return plugin.NextOrFailure(c.Name(), c.Next, ctx, crr, r)
}
@ -127,6 +127,13 @@ var (
Name: "prefetch_total",
Help: "The number of time the cache has prefetched a cached item.",
})
cacheDrops = prometheus.NewCounter(prometheus.CounterOpts{
Namespace: plugin.Namespace,
Subsystem: "cache",
Name: "drops_total",
Help: "The number responses that are not cached, because the reply is malformed.",
})
)
var once sync.Once