request.Request: remove useless function (#2714)

ErrorMessage was a very shallow function that didn't add anything.
Remove it and remove its usage.
Signed-off-by: Miek Gieben <miek@miek.nl>

plugin/forward/forward.go

@@ -146,7 +146,8 @@ func (f *Forward) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg
 		if !state.Match(ret) {
 			debug.Hexdumpf(ret, "Wrong reply for id: %d, %s %d", ret.Id, state.QName(), state.QType())
 
-			formerr := state.ErrorMessage(dns.RcodeFormatError)
+			formerr := new(dns.Msg)
+			formerr.SetRcode(state.Req, dns.RcodeFormatError)
 			w.WriteMsg(formerr)
 			return 0, taperr
 		}

plugin/grpc/grpc.go

@@ -77,7 +77,8 @@ func (g *GRPC) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (
 		if !state.Match(ret) {
 			debug.Hexdumpf(ret, "Wrong reply for id: %d, %s %d", ret.Id, state.QName(), state.QType())
 
-			formerr := state.ErrorMessage(dns.RcodeFormatError)
+			formerr := new(dns.Msg)
+			formerr.SetRcode(state.Req, dns.RcodeFormatError)
 			w.WriteMsg(formerr)
 			return 0, nil
 		}

request/request.go

@@ -433,14 +433,6 @@ func (r *Request) QClass() uint16 {
 
 }
 
-// ErrorMessage returns an error message suitable for sending
-// back to the client.
-func (r *Request) ErrorMessage(rcode int) *dns.Msg {
-	m := new(dns.Msg)
-	m.SetRcode(r.Req, rcode)
-	return m
-}
-
 // Clear clears all caching from Request s.
 func (r *Request) Clear() {
 	r.name = ""