Cleanup docs and the chaos middleware

Make the CH middleware actually work. Needs a bit of a hack to route

the fake version.bind and friends zone to the correct handler. Fiddle

with the order in directive.go so that CH queries get logged as well.



Secondly add class rewriting to the rewrite middleware handler and also

log the class by default.

middleware/rewrite/README.md

@@ -16,6 +16,9 @@ rewrite from to
 If from *and* to look like a DNS type (`A`, `MX`, etc.) the type of the message will be rewriten,
 i.e. to rewrite ANY queries to HINFO, use `rewrite ANY HINFO`.
 
+If from *and* to look like a DNS class (`IN`, `CH`, or `HS`) the class of the message will be
+rewritten. I.e. to rewrite CH queries to IN use `rewrite CH IN`.
+
 If it does not look like a type a name is assumed and the qname in the message is rewritten, this
 needs to be a full match of the name `rewrite miek.nl example.org`.
 

middleware/rewrite/rewrite.go

@@ -58,24 +58,29 @@ type Rule interface {
 // the type of the request is rewritten, otherwise the name is.
 // Note: TSIG signed requests will be invalid.
 type SimpleRule struct {
-	From, To         string
-	fromType, toType uint16
+	From, To           string
+	fromType, toType   uint16
+	fromClass, toClass uint16
 }
 
 // NewSimpleRule creates a new Simple Rule
 func NewSimpleRule(from, to string) SimpleRule {
 	tpf := dns.StringToType[from]
 	tpt := dns.StringToType[to]
-	// It's only a type if uppercase is used.
+	clf := dns.StringToClass[from]
+	clt := dns.StringToClass[to]
+	// It's only a type/class if uppercase is used.
 	if from != strings.ToUpper(from) {
 		tpf = 0
+		clf = 0
 		from = middleware.Name(from).Normalize()
 	}
 	if to != strings.ToUpper(to) {
 		tpt = 0
+		clt = 0
 		to = middleware.Name(to).Normalize()
 	}
-	return SimpleRule{From: from, To: to, fromType: tpf, toType: tpt}
+	return SimpleRule{From: from, To: to, fromType: tpf, toType: tpt, fromClass: clf, toClass: clt}
 }
 
 // Rewrite rewrites the the current request.
@@ -89,6 +94,15 @@ func (s SimpleRule) Rewrite(r *dns.Msg) Result {
 		return RewriteIgnored
 	}
 
+	// class rewrite
+	if s.fromClass > 0 && s.toClass > 0 {
+		if r.Question[0].Qclass == s.fromClass {
+			r.Question[0].Qclass = s.toClass
+			return RewriteDone
+		}
+		return RewriteIgnored
+	}
+
 	// name rewite
 	if s.From == r.Question[0].Name {
 		r.Question[0].Name = s.To