From 16e50ec5f82aa3969b27f5b8fa750919ad0a115a Mon Sep 17 00:00:00 2001
From: Miek Gieben <miek@miek.nl>
Date: Fri, 25 Mar 2016 17:23:06 +0000
Subject: [PATCH] Add state.SizeAndDo()

This methods returns an OPT record which can be used to create a new
message with the same bufsize and Do bit as the original one.
---
 middleware/proxy/lookup.go       |  6 ++--
 middleware/proxy/reverseproxy.go |  1 -
 middleware/state.go              | 54 ++++++++++++++++----------------
 3 files changed, 31 insertions(+), 30 deletions(-)

diff --git a/middleware/proxy/lookup.go b/middleware/proxy/lookup.go
index 599ecf12a..564b662c5 100644
--- a/middleware/proxy/lookup.go
+++ b/middleware/proxy/lookup.go
@@ -55,8 +55,10 @@ func New(hosts []string) Proxy {
 func (p Proxy) Lookup(state middleware.State, name string, tpe uint16) (*dns.Msg, error) {
 	req := new(dns.Msg)
 	req.SetQuestion(name, tpe)
-	// TODO(miek):
-	// USE STATE FOR DNSSEC ETCD BUFSIZE BLA BLA
+
+	opt := state.SizeAndDo()
+	req.Extra = []dns.RR{opt}
+
 	return p.lookup(state, req)
 }
 
diff --git a/middleware/proxy/reverseproxy.go b/middleware/proxy/reverseproxy.go
index 460b294a8..efe6f47d2 100644
--- a/middleware/proxy/reverseproxy.go
+++ b/middleware/proxy/reverseproxy.go
@@ -12,7 +12,6 @@ type ReverseProxy struct {
 }
 
 func (p ReverseProxy) ServeDNS(w dns.ResponseWriter, r *dns.Msg, extra []dns.RR) error {
-	// TODO(miek): use extra to EDNS0.
 	var (
 		reply *dns.Msg
 		err   error
diff --git a/middleware/state.go b/middleware/state.go
index fa8ef74a9..f4cd43542 100644
--- a/middleware/state.go
+++ b/middleware/state.go
@@ -19,17 +19,12 @@ type State struct {
 }
 
 // Now returns the current timestamp in the specified format.
-func (s State) Now(format string) string {
-	return time.Now().Format(format)
-}
+func (s State) Now(format string) string { return time.Now().Format(format) }
 
-// NowDate returns the current date/time that can be used
-// in other time functions.
-func (s State) NowDate() time.Time {
-	return time.Now()
-}
+// NowDate returns the current date/time that can be used in other time functions.
+func (s State) NowDate() time.Time { return time.Now() }
 
-// Header gets the value of a header.
+// Header gets the heaser of the request in State.
 func (s State) Header() *dns.RR_Header {
 	// TODO(miek)
 	return nil
@@ -107,36 +102,41 @@ func (s State) Size() int {
 	return dns.MinMsgSize
 }
 
-// Type returns the type of the question as a string.
-func (s State) Type() string {
-	return dns.Type(s.Req.Question[0].Qtype).String()
+// SizeAndDo returns a ready made OPT record that the reflects the intent
+// from the state. This can be added to upstream requests that will then
+// hopefully return a message that is understandable by the original client.
+func (s State) SizeAndDo() *dns.OPT {
+	size := s.Size()
+	Do := s.Do()
+
+	o := new(dns.OPT)
+	o.Hdr.Name = "."
+	o.Hdr.Rrtype = dns.TypeOPT
+	o.SetUDPSize(uint16(size))
+	if Do {
+		o.SetDo()
+	}
+	return o
 }
 
+// Type returns the type of the question as a string.
+func (s State) Type() string { return dns.Type(s.Req.Question[0].Qtype).String() }
+
 // QType returns the type of the question as a uint16.
-func (s State) QType() uint16 {
-	return s.Req.Question[0].Qtype
-}
+func (s State) QType() uint16 { return s.Req.Question[0].Qtype }
 
 // Name returns the name of the question in the request. Note
 // this name will always have a closing dot and will be lower cased.
-func (s State) Name() string {
-	return strings.ToLower(dns.Name(s.Req.Question[0].Name).String())
-}
+func (s State) Name() string { return strings.ToLower(dns.Name(s.Req.Question[0].Name).String()) }
 
 // QName returns the name of the question in the request.
-func (s State) QName() string {
-	return dns.Name(s.Req.Question[0].Name).String()
-}
+func (s State) QName() string { return dns.Name(s.Req.Question[0].Name).String() }
 
 // Class returns the class of the question in the request.
-func (s State) Class() string {
-	return dns.Class(s.Req.Question[0].Qclass).String()
-}
+func (s State) Class() string { return dns.Class(s.Req.Question[0].Qclass).String() }
 
 // QClass returns the class of the question in the request.
-func (s State) QClass() uint16 {
-	return s.Req.Question[0].Qclass
-}
+func (s State) QClass() uint16 { return s.Req.Question[0].Qclass }
 
 // ErrorMessage returns an error message suitable for sending
 // back to the client.