Mirrors/coredns
1
0
Fork 0
mirror of https://github.com/coredns/coredns.git synced 2025-10-31 10:13:14 -04:00
Code Issues Packages Projects Releases Wiki Activity

plugin/file: respond correctly to IXFR message (#3177)

Browse Source 
* plugin/file: respond correctly to IXFR message

Respond with a sing SOA record to an IXFR request if the SOA serials
match.

The added test fails on the current code with:

~~~
=== RUN   TestIxfrResponse
--- FAIL: TestIxfrResponse (0.00s)
    secondary_test.go:122: Expected answer section with single RR
FAIL
exit status 1
~~~

And obviously passes with the new code. This should cut down on the
weird number of zone transfers that I was seeing. At some point IXFR
support might be cool.

Fixes: #3176

Signed-off-by: Miek Gieben <miek@miek.nl>

* reuse code

Signed-off-by: Miek Gieben <miek@miek.nl>

* Sligtht tweaks

Signed-off-by: Miek Gieben <miek@miek.nl>
This commit is contained in:
Miek Gieben
2019-08-26 08:14:43 +00:00
committed by GitHub
parent e08d3335b0
commit d65cd709cd
2 changed files with 87 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

41
plugin/file/xfr.go
View File

@@ -26,6 +26,15 @@ func (x Xfr) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (in
return 0, plugin.Error(x.Name(), fmt.Errorf("xfr called with non transfer type: %d", state.QType()))
}
// For IXFR we take the SOA in the IXFR message (if there), compare it what we have and then decide to do an
// AXFR or just reply with one SOA message back.
if state.QType() == dns.TypeIXFR {
code, _ := x.ServeIxfr(ctx, w, r)
if plugin.ClientWrite(code) {
return code, nil
}
}
records := x.All()
if len(records) == 0 {
return dns.RcodeServerFailure, nil
@@ -63,4 +72,36 @@ func (x Xfr) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (in
// Name implements the plugin.Handler interface.
func (x Xfr) Name() string { return "xfr" }
// ServeIxfr checks if we need to serve a simpler IXFR for the incoming message.
// See RFC 1995 Section 3: "... and the authority section containing the SOA record of client's version of the zone."
// and Section 2, paragraph 4 where we only need to echo the SOA record back.
// This function must be called when the qtype is IXFR. It returns a plugin.ClientWrite(code) == false, when it didn't
// write anything and we should perform an AXFR.
func (x Xfr) ServeIxfr(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (int, error) {
if len(r.Ns) != 1 {
return dns.RcodeServerFailure, nil
}
soa, ok := r.Ns[0].(*dns.SOA)
if !ok {
return dns.RcodeServerFailure, nil
}
x.RLock()
if x.Apex.SOA == nil {
x.RUnlock()
return dns.RcodeServerFailure, nil
}
serial := x.Apex.SOA.Serial
x.RUnlock()
if soa.Serial == serial { // Section 2, para 4; echo SOA back. We have the same zone
m := new(dns.Msg)
m.SetReply(r)
m.Answer = []dns.RR{soa}
w.WriteMsg(m)
return 0, nil
}
return dns.RcodeServerFailure, nil
}
const transferLength = 1000 // Start a new envelop after message reaches this size in bytes. Intentionally small to test multi envelope parsing.