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Fix EDNS0 compliance (#2357)

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* Fix EDNS0 compliance

Do SizeAndDo in the server (ScrubWriter) and remove all uses of this
from the plugins. Also *always* do it. This is to get into compliance
for https://dnsflagday.net/.

The pkg/edns0 now exports the EDNS0 options we understand; this is
exported to allow plugins add things there. The *rewrite* plugin used
this to add custom EDNS0 option codes that the server needs to
understand.

This also needs a new release of miekg/dns because it triggered a
race-condition that was basicly there forever.

See:
* https://github.com/miekg/dns/issues/857
* https://github.com/miekg/dns/pull/859

Running a test instance and pointing the https://ednscomp.isc.org/ednscomp
to it shows the tests are now fixed:

~~~
EDNS Compliance Tester
Checking: 'miek.nl' as at 2018-12-01T17:53:15Z

miek.nl. @147.75.204.203 (drone.coredns.io.): dns=ok edns=ok edns1=ok edns@512=ok ednsopt=ok edns1opt=ok do=ok ednsflags=ok docookie=ok edns512tcp=ok optlist=ok
miek.nl. @2604:1380:2002:a000::1 (drone.coredns.io.): dns=ok edns=ok edns1=ok edns@512=ok ednsopt=ok edns1opt=ok do=ok ednsflags=ok docookie=ok edns512tcp=ok optlist=ok

All Ok
Codes
ok - test passed.
~~~

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

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

* typos in comments

Signed-off-by: Miek Gieben <miek@miek.nl>
This commit is contained in:
Miek Gieben 2018-12-06 21:18:11 +00:00 • committed by GitHub
parent f51c110511
commit fc667b98e0
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16 changed files with 113 additions and 20 deletions
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12
request/request.go
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@ -194,7 +194,7 @@ func (r *Request) Size() int {
// SizeAndDo adds an OPT record that the reflects the intent from request.
// The returned bool indicated if an record was found and normalised.
func (r *Request) SizeAndDo(m *dns.Msg) bool {
o := r.Req.IsEdns0() // TODO(miek): speed this up
o := r.Req.IsEdns0()
if o == nil {
return false
}
@ -208,6 +208,10 @@ func (r *Request) SizeAndDo(m *dns.Msg) bool {
mo.SetUDPSize(o.UDPSize())
mo.Hdr.Ttl &= 0xff00 // clear flags
if len(o.Option) > 0 {
o.Option = supportedOptions(o.Option)
}
if odo {
mo.SetDo()
}
@ -219,6 +223,10 @@ func (r *Request) SizeAndDo(m *dns.Msg) bool {
o.SetVersion(0)
o.Hdr.Ttl &= 0xff00 // clear flags
if len(o.Option) > 0 {
o.Option = supportedOptions(o.Option)
}
if odo {
o.SetDo()
}
@ -305,7 +313,6 @@ func (r *Request) Scrub(reply *dns.Msg) *dns.Msg {
}
if rl <= size {
r.SizeAndDo(reply)
return reply
}
@ -341,7 +348,6 @@ func (r *Request) Scrub(reply *dns.Msg) *dns.Msg {
// this extra m-1 step does make it fit in the client's buffer however.
}
r.SizeAndDo(reply)
reply.Truncated = true
return reply
}