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authorGravatar Miek Gieben <miek@miek.nl> 2018-12-06 21:18:11 +0000
committerGravatar GitHub <noreply@github.com> 2018-12-06 21:18:11 +0000
commitfc667b98e0587dcebe19183b83f99059513dba0e (patch)
treefe45c8a3659458427d2114c4767308b362a807af /request
parentf51c110511c13b80c7d7234c3d56dbefa79705a2 (diff)
downloadcoredns-fc667b98e0587dcebe19183b83f99059513dba0e.tar.gz
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Fix EDNS0 compliance (#2357)
* 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>
Diffstat (limited to 'request')
-rw-r--r--request/edns0.go31
-rw-r--r--request/request.go12
-rw-r--r--request/request_test.go8
-rw-r--r--request/writer.go2
4 files changed, 42 insertions, 11 deletions
diff --git a/request/edns0.go b/request/edns0.go
new file mode 100644
index 000000000..89eb6b468
--- /dev/null
+++ b/request/edns0.go
@@ -0,0 +1,31 @@
+package request
+
+import (
+ "github.com/coredns/coredns/plugin/pkg/edns"
+
+ "github.com/miekg/dns"
+)
+
+func supportedOptions(o []dns.EDNS0) []dns.EDNS0 {
+ var supported = make([]dns.EDNS0, 0, 3)
+ // For as long as possible try avoid looking up in the map, because that need an Rlock.
+ for _, opt := range o {
+ switch code := opt.Option(); code {
+ case dns.EDNS0NSID:
+ fallthrough
+ case dns.EDNS0EXPIRE:
+ fallthrough
+ case dns.EDNS0COOKIE:
+ fallthrough
+ case dns.EDNS0TCPKEEPALIVE:
+ fallthrough
+ case dns.EDNS0PADDING:
+ supported = append(supported, opt)
+ default:
+ if edns.SupportedOption(code) {
+ supported = append(supported, opt)
+ }
+ }
+ }
+ return supported
+}
diff --git a/request/request.go b/request/request.go
index 105cd8528..52bf8629b 100644
--- a/request/request.go
+++ b/request/request.go
@@ -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
}
diff --git a/request/request_test.go b/request/request_test.go
index 5e814f76e..4411c6a82 100644
--- a/request/request_test.go
+++ b/request/request_test.go
@@ -123,10 +123,6 @@ func TestRequestScrubExtraEdns0(t *testing.T) {
if reply.Truncated {
t.Errorf("Want scrub to not set truncated bit")
}
- opt := reply.Extra[len(reply.Extra)-1]
- if opt.Header().Rrtype != dns.TypeOPT {
- t.Errorf("Last RR must be OPT record")
- }
}
func TestRequestScrubExtraRegression(t *testing.T) {
@@ -153,10 +149,6 @@ func TestRequestScrubExtraRegression(t *testing.T) {
if reply.Truncated {
t.Errorf("Want scrub to not set truncated bit")
}
- opt := reply.Extra[len(reply.Extra)-1]
- if opt.Header().Rrtype != dns.TypeOPT {
- t.Errorf("Last RR must be OPT record")
- }
}
func TestTruncation(t *testing.T) {
diff --git a/request/writer.go b/request/writer.go
index ffbbe93e3..67be53ebb 100644
--- a/request/writer.go
+++ b/request/writer.go
@@ -15,6 +15,8 @@ func NewScrubWriter(req *dns.Msg, w dns.ResponseWriter) *ScrubWriter { return &S
// scrub on the message m and will then write it to the client.
func (s *ScrubWriter) WriteMsg(m *dns.Msg) error {
state := Request{Req: s.req, W: s.ResponseWriter}
+
n := state.Scrub(m)
+ state.SizeAndDo(n)
return s.ResponseWriter.WriteMsg(n)
}