refactor: new dns app

app/router/command/config.go

@@ -28,6 +28,12 @@ func (c routingContext) GetTargetPort() net.Port {
 	return net.Port(c.RoutingContext.GetTargetPort())
 }
 
+// GetSkipDNSResolve is a mock implementation here to match the interface,
+// SkipDNSResolve is set from dns module, no use if coming from a protobuf object?
+func (c routingContext) GetSkipDNSResolve() bool {
+	return false
+}
+
 // AsRoutingContext converts a protobuf RoutingContext into an implementation of routing.Context.
 func AsRoutingContext(r *RoutingContext) routing.Context {
 	return routingContext{r}

app/router/router.go

@@ -80,7 +80,13 @@ func (r *Router) PickRoute(ctx routing.Context) (routing.Route, error) {
 }
 
 func (r *Router) pickRouteInternal(ctx routing.Context) (*Rule, routing.Context, error) {
-	if r.domainStrategy == Config_IpOnDemand {
+
+	// SkipDNSResolve is set from DNS module.
+	// the DOH remote server maybe a domain name,
+	// this prevents cycle resolving dead loop
+	skipDNSResolve := ctx.GetSkipDNSResolve()
+
+	if r.domainStrategy == Config_IpOnDemand && !skipDNSResolve {
 		ctx = routing_dns.ContextWithDNSClient(ctx, r.dns)
 	}
 
@@ -90,7 +96,7 @@ func (r *Router) pickRouteInternal(ctx routing.Context) (*Rule, routing.Context,
 		}
 	}
 
-	if r.domainStrategy != Config_IpIfNonMatch || len(ctx.GetTargetDomain()) == 0 {
+	if r.domainStrategy != Config_IpIfNonMatch || len(ctx.GetTargetDomain()) == 0 || skipDNSResolve {
 		return nil, ctx, common.ErrNoClue
 	}