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-rw-r--r--plugin/erratic/erratic.go6
-rw-r--r--plugin/erratic/erratic_test.go16
-rw-r--r--plugin/erratic/setup.go2
-rw-r--r--request/request.go8
-rw-r--r--request/request_test.go10
-rw-r--r--request/writer.go4
-rw-r--r--test/compression_scrub_test.go60
7 files changed, 93 insertions, 13 deletions
diff --git a/plugin/erratic/erratic.go b/plugin/erratic/erratic.go
index 3460f3bca..f60e605d1 100644
--- a/plugin/erratic/erratic.go
+++ b/plugin/erratic/erratic.go
@@ -19,6 +19,7 @@ type Erratic struct {
duration time.Duration
truncate uint64
+ large bool // undocumented feature; return large responses for A request (>512B, to test compression).
q uint64 // counter of queries
}
@@ -57,6 +58,11 @@ func (e *Erratic) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg
rr := *(rrA.(*dns.A))
rr.Header().Name = state.QName()
m.Answer = append(m.Answer, &rr)
+ if e.large {
+ for i := 0; i < 29; i++ {
+ m.Answer = append(m.Answer, &rr)
+ }
+ }
case dns.TypeAAAA:
rr := *(rrAAAA.(*dns.AAAA))
rr.Header().Name = state.QName()
diff --git a/plugin/erratic/erratic_test.go b/plugin/erratic/erratic_test.go
index 406fd8774..ec2ec5c0a 100644
--- a/plugin/erratic/erratic_test.go
+++ b/plugin/erratic/erratic_test.go
@@ -98,3 +98,19 @@ func TestAxfr(t *testing.T) {
t.Errorf("Expected for record to be %d, got %d", dns.TypeSOA, x)
}
}
+
+func TestErratic(t *testing.T) {
+ e := &Erratic{drop: 0, delay: 0}
+
+ ctx := context.TODO()
+
+ req := new(dns.Msg)
+ req.SetQuestion("example.org.", dns.TypeA)
+
+ rec := dnstest.NewRecorder(&test.ResponseWriter{})
+ e.ServeDNS(ctx, rec, req)
+
+ if rec.Msg.Answer[0].Header().Rrtype != dns.TypeA {
+ t.Errorf("Expected A response, got %d type", rec.Msg.Answer[0].Header().Rrtype)
+ }
+}
diff --git a/plugin/erratic/setup.go b/plugin/erratic/setup.go
index 52c4d245c..79e4449ee 100644
--- a/plugin/erratic/setup.go
+++ b/plugin/erratic/setup.go
@@ -104,6 +104,8 @@ func parseErratic(c *caddy.Controller) (*Erratic, error) {
return nil, fmt.Errorf("illegal amount value given %q", args[0])
}
e.truncate = uint64(amount)
+ case "large":
+ e.large = true
default:
return nil, c.Errf("unknown property '%s'", c.Val())
}
diff --git a/request/request.go b/request/request.go
index c4e4eea3c..f560612c8 100644
--- a/request/request.go
+++ b/request/request.go
@@ -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
diff --git a/request/request_test.go b/request/request_test.go
index 6685ad3b3..bfc95bc5e 100644
--- a/request/request_test.go
+++ b/request/request_test.go
@@ -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)
}
diff --git a/request/writer.go b/request/writer.go
index ef0c14417..ffbbe93e3 100644
--- a/request/writer.go
+++ b/request/writer.go
@@ -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)
}
diff --git a/test/compression_scrub_test.go b/test/compression_scrub_test.go
new file mode 100644
index 000000000..b18f1fe0a
--- /dev/null
+++ b/test/compression_scrub_test.go
@@ -0,0 +1,60 @@
+package test
+
+import (
+ "net"
+ "testing"
+
+ "github.com/miekg/dns"
+)
+
+func TestCompressScrub(t *testing.T) {
+ corefile := `example.org:0 {
+ erratic {
+ drop 0
+ delay 0
+ large
+ }
+ }`
+
+ i, udp, _, err := CoreDNSServerAndPorts(corefile)
+ if err != nil {
+ t.Fatalf("Could not get CoreDNS serving instance: %s", err)
+ }
+ defer i.Stop()
+
+ c, err := net.Dial("udp", udp)
+ if err != nil {
+ t.Fatalf("Could not dial %s", err)
+ }
+ m := new(dns.Msg)
+ m.SetQuestion("example.org.", dns.TypeA)
+ q, _ := m.Pack()
+
+ c.Write(q)
+ buf := make([]byte, 1024)
+ n, err := c.Read(buf)
+ if err != nil || n == 0 {
+ t.Errorf("Expected reply, got: %s", err)
+ return
+ }
+ if n >= 512 {
+ t.Fatalf("Expected returned packet to be < 512, got %d", n)
+ }
+ buf = buf[:n]
+ // If there is compression in the returned packet we should look for compression pointers, if found
+ // the pointers should return to the domain name in the query (the first domain name that's avaiable for
+ // compression. This means we're looking for a combo where the pointers is detected and the offset is 12
+ // the position of the first name after the header. The erratic plugin adds 30 RRs that should all be compressed.
+ found := 0
+ for i := 0; i < len(buf)-1; i++ {
+ if buf[i]&0xC0 == 0xC0 {
+ off := (int(buf[i])^0xC0)<<8 | int(buf[i+1])
+ if off == 12 {
+ found++
+ }
+ }
+ }
+ if found != 30 {
+ t.Errorf("Failed to find all compression pointers in the packet, wanted 30, got %d", found)
+ }
+}
generated by cgit v1.2.3 (git 2.39.1) at 2025-07-22 08:09:41 +0000