Default to scrubbing replies in the server (#2012)

Every plugin needs to deal with EDNS0 and should call Scrub to make a
message fit the client's buffer. Move this functionality into the server
and wrapping the ResponseWriter into a ScrubWriter that handles these
bits for us. Result:

Less code and faster, because multiple chained plugins could all be
calling scrub and SizeAndDo - now there is just one place.

Most tests in file/* and dnssec/* needed adjusting because in those unit
tests you don't see OPT RRs anymore. The DNSSEC signer was also looking
at the returned OPT RR to see if it needed to sign - as those are now
added by the server (and thus later), this needed to change slightly.

Scrub itself still exist (for backward compat reasons), but has been
made a noop. Scrub has been renamed to scrub as it should not be used by
external plugins.

Fixes: #2010

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

1 files changed, 3 insertions, 11 deletions

diff --git a/plugin/dnssec/handler_test.go b/plugin/dnssec/handler_test.go
index a1c35c635..ed9ddc5a5 100644
--- a/plugin/dnssec/handler_test.go
+++ b/plugin/dnssec/handler_test.go
@@ -56,7 +56,6 @@ var dnsTestCases = []test.Case{
 			test.NS("miek.nl.	1800	IN	NS	linode.atoom.net."),
 			test.RRSIG("miek.nl.	1800	IN	RRSIG	NS 13 2 3600 20161217114912 20161209084912 18512 miek.nl. ad9gA8VWgF1H8ze9/0Rk2Q=="),
 		},
-		Extra: []dns.RR{test.OPT(4096, true)},
 	},
 	{
 		Qname: "www.miek.nl.", Qtype: dns.TypeAAAA, Do: true,
@@ -70,7 +69,6 @@ var dnsTestCases = []test.Case{
 			test.NS("miek.nl.	1800	IN	NS	linode.atoom.net."),
 			test.RRSIG("miek.nl.	1800	IN	RRSIG	NS 13 2 3600 20161217114912 20161209084912 18512 miek.nl. ad9gA8VWgF1H8ze9/0Rk2Q=="),
 		},
-		Extra: []dns.RR{test.OPT(4096, true)},
 	},
 	{
 		Qname: "wwwww.miek.nl.", Qtype: dns.TypeAAAA, Do: true,
@@ -80,7 +78,6 @@ var dnsTestCases = []test.Case{
 			test.NSEC("wwwww.miek.nl.	1800	IN	NSEC	\\000.wwwww.miek.nl. A HINFO TXT LOC SRV CERT SSHFP RRSIG NSEC TLSA HIP OPENPGPKEY SPF"),
 			test.RRSIG("wwwww.miek.nl.	1800	IN	RRSIG	NSEC 13 3 3600 20171220135446 20171212105446 18512 miek.nl. cVUQWs8xw=="),
 		},
-		Extra: []dns.RR{test.OPT(4096, true)},
 	},
 	{
 		Qname: "miek.nl.", Qtype: dns.TypeHINFO, Do: true,
@@ -90,12 +87,10 @@ var dnsTestCases = []test.Case{
 			test.RRSIG("miek.nl.	1800	IN	RRSIG	SOA 13 2 3600 20171220141741 20171212111741 18512 miek.nl. 8bLTReqmuQtw=="),
 			test.SOA("miek.nl.	1800	IN	SOA	linode.atoom.net. miek.miek.nl. 1282630057 14400 3600 604800 14400"),
 		},
-		Extra: []dns.RR{test.OPT(4096, true)},
 	},
 	{
 		Qname: "www.example.org.", Qtype: dns.TypeAAAA, Do: true,
 		Rcode: dns.RcodeServerFailure,
-		// Extra: []dns.RR{test.OPT(4096, true)}, // test.ErrorHandler is a simple handler that does not do EDNS on ServerFailure
 	},
 }
 
@@ -110,20 +105,18 @@ func TestLookupZone(t *testing.T) {
 	defer rm2()
 	c := cache.New(defaultCap)
 	dh := New([]string{"miek.nl."}, []*DNSKEY{dnskey}, fm, c)
-	ctx := context.TODO()
 
 	for _, tc := range dnsTestCases {
 		m := tc.Msg()
 
 		rec := dnstest.NewRecorder(&test.ResponseWriter{})
-		_, err := dh.ServeDNS(ctx, rec, m)
+		_, err := dh.ServeDNS(context.TODO(), rec, m)
 		if err != nil {
 			t.Errorf("Expected no error, got %v\n", err)
 			return
 		}
 
-		resp := rec.Msg
-		test.SortAndCheck(t, resp, tc)
+		test.SortAndCheck(t, rec.Msg, tc)
 	}
 }
 
@@ -133,13 +126,12 @@ func TestLookupDNSKEY(t *testing.T) {
 	defer rm2()
 	c := cache.New(defaultCap)
 	dh := New([]string{"miek.nl."}, []*DNSKEY{dnskey}, test.ErrorHandler(), c)
-	ctx := context.TODO()
 
 	for _, tc := range dnssecTestCases {
 		m := tc.Msg()
 
 		rec := dnstest.NewRecorder(&test.ResponseWriter{})
-		_, err := dh.ServeDNS(ctx, rec, m)
+		_, err := dh.ServeDNS(context.TODO(), rec, m)
 		if err != nil {
 			t.Errorf("Expected no error, got %v\n", err)
 			return