1 files changed, 60 insertions, 0 deletions
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)
+	}
+}