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server: actually scrub response (#2225)

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* server: actually scrub response

Did all the worked, hooked it up wrongly :(

This also needs test, but those are hard(er) because we only receive
packets after they have been decoded; i.e. we never see the wirefmt.

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

* Add tests

Add a test for checking is compression pointers are set in the packet.
This also adds an undocumented 'large' feature to the erratic plugin to
send large responses that should be compressed.

Commenting the Scrub out in server results in:

=== RUN   TestCompressScrub
--- FAIL: TestCompressScrub (0.00s)
    compression_scrub_test.go:41: Expected returned packet to be < 512, got 839
FAIL
exit status 1
FAIL    github.com/coredns/coredns/test 0.036s

Actually checking the size might be easier, but lets be thorough here
and check the pointers them selves.

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

* Fix tests

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

* plugin erratic: fix e.large

always put an rr in the reply, fix e.large in erractic and add test to
check for it.

Signed-off-by: Miek Gieben <miek@miek.nl>
This commit is contained in:
Miek Gieben
2018-10-23 17:55:40 +01:00
committed by John Belamaric
parent 96529b2c50
commit 898b1ef316
7 changed files with 93 additions and 13 deletions
Download Patch File Download Diff File Expand all files Collapse all files

8
request/request.go
View File

@@ -226,11 +226,7 @@ func (r *Request) SizeAndDo(m *dns.Msg) bool {
return true
}
// Scrub is a noop function, added for backwards compatibility reasons. The original Scrub is now called
// automatically by the server on writing the reply. See ScrubWriter.
func (r *Request) Scrub(reply *dns.Msg) (*dns.Msg, int) { return reply, 0 }
// scrub scrubs the reply message so that it will fit the client's buffer. It will first
// Scrub scrubs the reply message so that it will fit the client's buffer. It will first
// check if the reply fits without compression and then *with* compression.
// Scrub will then use binary search to find a save cut off point in the additional section.
// If even *without* the additional section the reply still doesn't fit we
@@ -238,7 +234,7 @@ func (r *Request) Scrub(reply *dns.Msg) (*dns.Msg, int) { return reply, 0 }
// we set the TC bit on the reply; indicating the client should retry over TCP.
// Note, the TC bit will be set regardless of protocol, even TCP message will
// get the bit, the client should then retry with pigeons.
func (r *Request) scrub(reply *dns.Msg) *dns.Msg {
func (r *Request) Scrub(reply *dns.Msg) *dns.Msg {
size := r.Size()
reply.Compress = false

10
request/request_test.go
View File

@@ -73,7 +73,7 @@ func TestRequestScrubAnswer(t *testing.T) {
fmt.Sprintf("large.example.com. 10 IN SRV 0 0 80 10-0-0-%d.default.pod.k8s.example.com.", i)))
}
req.scrub(reply)
req.Scrub(reply)
if want, got := req.Size(), reply.Len(); want < got {
t.Errorf("Want scrub to reduce message length below %d bytes, got %d bytes", want, got)
}
@@ -94,7 +94,7 @@ func TestRequestScrubExtra(t *testing.T) {
fmt.Sprintf("large.example.com. 10 IN SRV 0 0 80 10-0-0-%d.default.pod.k8s.example.com.", i)))
}
req.scrub(reply)
req.Scrub(reply)
if want, got := req.Size(), reply.Len(); want < got {
t.Errorf("Want scrub to reduce message length below %d bytes, got %d bytes", want, got)
}
@@ -116,7 +116,7 @@ func TestRequestScrubExtraEdns0(t *testing.T) {
fmt.Sprintf("large.example.com. 10 IN SRV 0 0 80 10-0-0-%d.default.pod.k8s.example.com.", i)))
}
req.scrub(reply)
req.Scrub(reply)
if want, got := req.Size(), reply.Len(); want < got {
t.Errorf("Want scrub to reduce message length below %d bytes, got %d bytes", want, got)
}
@@ -146,7 +146,7 @@ func TestRequestScrubExtraRegression(t *testing.T) {
fmt.Sprintf("10-0-0-%d.default.pod.k8s.example.com. 10 IN A 10.0.0.%d", i, i)))
}
reply = req.scrub(reply)
reply = req.Scrub(reply)
if want, got := req.Size(), reply.Len(); want < got {
t.Errorf("Want scrub to reduce message length below %d bytes, got %d bytes", want, got)
}
@@ -171,7 +171,7 @@ func TestRequestScrubAnswerExact(t *testing.T) {
reply.Answer = append(reply.Answer, test.A(fmt.Sprintf("large.example.com. 10 IN A 127.0.0.%d", i)))
}
req.scrub(reply)
req.Scrub(reply)
if want, got := req.Size(), reply.Len(); want < got {
t.Errorf("Want scrub to reduce message length below %d bytes, got %d bytes", want, got)
}

4
request/writer.go
View File

@@ -15,6 +15,6 @@ 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}
new, _ := state.Scrub(m)
return s.ResponseWriter.WriteMsg(new)
n := state.Scrub(m)
return s.ResponseWriter.WriteMsg(n)
}