make CoreDNS DoH Server (#1619)

* WIP: make CoreDNS DoH Server

* It works

* Fix tests

* Review from Tom - on diff. PR

* correct mime type

* Cleanups and use the pkg/nonwriter

* rename and updates

* implement get

* implement GET

* Code review comments

* correct context

* tweaks

* code review

plugin/normalize.go

@@ -71,6 +71,8 @@ func (h Host) Normalize() string {
 		s = s[len(TransportDNS+"://"):]
 	case strings.HasPrefix(s, TransportGRPC+"://"):
 		s = s[len(TransportGRPC+"://"):]
+	case strings.HasPrefix(s, TransportHTTPS+"://"):
+		s = s[len(TransportHTTPS+"://"):]
 	}
 
 	// The error can be ignore here, because this function is called after the corefile
@@ -138,7 +140,8 @@ func SplitHostPort(s string) (host, port string, ipnet *net.IPNet, err error) {
 
 // Duplicated from core/dnsserver/address.go !
 const (
-	TransportDNS  = "dns"
-	TransportTLS  = "tls"
-	TransportGRPC = "grpc"
+	TransportDNS   = "dns"
+	TransportTLS   = "tls"
+	TransportGRPC  = "grpc"
+	TransportHTTPS = "https"
 )

plugin/pkg/nonwriter/nonwriter.go

@@ -2,6 +2,8 @@
 package nonwriter
 
 import (
+	"net"
+
 	"github.com/miekg/dns"
 )
 
@@ -9,6 +11,11 @@ import (
 type Writer struct {
 	dns.ResponseWriter
 	Msg *dns.Msg
+
+	// Raddr is the remote's address. This can be optionally set.
+	Raddr net.Addr
+	// Laddr is our address. This can be optionally set.
+	Laddr net.Addr
 }
 
 // New makes and returns a new NonWriter.
@@ -20,4 +27,8 @@ func (w *Writer) WriteMsg(res *dns.Msg) error {
 	return nil
 }
 
-func (w *Writer) Write(buf []byte) (int, error) { return len(buf), nil }
+// RemoteAddr returns the remote address.
+func (w *Writer) RemoteAddr() net.Addr { return w.Raddr }
+
+// LocalAddr returns the local address.
+func (w *Writer) LocalAddr() net.Addr { return w.Laddr }