proxy: add quic session to dns context

proxy/dns_context.go

@@ -26,7 +26,8 @@ type DNSContext struct {
 	// If set, Resolve() uses it instead of default servers
 	CustomUpstreamConfig *UpstreamConfig
 
-	// Conn - underlying client connection. Can be null in the case of DOH.
+	// Conn is the underlying client connection.  It is nil if Proto is
+	// ProtoDNSCrypt, ProtoHTTPS, or ProtoQUIC.
 	Conn net.Conn
 
 	// localIP - local IP address (for UDP socket to call udpMakeOOBWithSrc)
@@ -40,9 +41,14 @@ type DNSContext struct {
 	// DNSCryptResponseWriter - necessary to respond to a DNSCrypt query
 	DNSCryptResponseWriter dnscrypt.ResponseWriter
 
-	// QUICStream - QUIC stream from which we got the query (for DOQ only)
+	// QUICStream is the QUIC stream from which we got the query.  For
+	// ProtoQUIC only.
 	QUICStream quic.Stream
 
+	// QUICSession is the QUIC session from which we got the query.  For
+	// ProtoQUIC only.
+	QUICSession quic.Session
+
 	ecsReqIP   net.IP // ECS IP used in request
 	ecsReqMask uint8  // ECS mask used in request
 }

proxy/server_quic.go

@@ -138,10 +138,11 @@ func (p *Proxy) handleQUICStream(stream quic.Stream, session quic.Session) {
 	}
 
 	d := &DNSContext{
-		Proto:      ProtoQUIC,
-		Req:        &msg,
-		Addr:       session.RemoteAddr(),
-		QUICStream: stream,
+		Proto:       ProtoQUIC,
+		Req:         &msg,
+		Addr:        session.RemoteAddr(),
+		QUICStream:  stream,
+		QUICSession: session,
 	}
 
 	err = p.handleDNSRequest(d)