From 83d6acf536164100d2f60b17217d3e5bd7f1bd2b Mon Sep 17 00:00:00 2001
From: yuhan6665 <1588741+yuhan6665@users.noreply.github.com>
Date: Fri, 29 Nov 2024 01:38:28 -0500
Subject: [PATCH] Fakedns should be optional

---
 app/dispatcher/default.go     | 2 +-
 app/dns/nameserver.go         | 6 +++++-
 app/dns/nameserver_fakedns.go | 4 ++++
 proxy/dns/dns.go              | 2 +-
 4 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/app/dispatcher/default.go b/app/dispatcher/default.go
index 42fca674..dbf58dad 100644
--- a/app/dispatcher/default.go
+++ b/app/dispatcher/default.go
@@ -106,7 +106,7 @@ func init() {
 	common.Must(common.RegisterConfig((*Config)(nil), func(ctx context.Context, config interface{}) (interface{}, error) {
 		d := new(DefaultDispatcher)
 		if err := core.RequireFeatures(ctx, func(om outbound.Manager, router routing.Router, pm policy.Manager, sm stats.Manager, dc dns.Client) error {
-			core.RequireFeatures(ctx, func(fdns dns.FakeDNSEngine) {
+			core.RequireFeatures(ctx, func(fdns dns.FakeDNSEngine) { // FakeDNSEngine is optional
 				d.fdns = fdns
 			})
 			return d.Init(config.(*Config), om, router, pm, sm, dc)
diff --git a/app/dns/nameserver.go b/app/dns/nameserver.go
index 1cca1453..ecba9aff 100644
--- a/app/dns/nameserver.go
+++ b/app/dns/nameserver.go
@@ -78,7 +78,11 @@ func NewClient(
 ) (*Client, error) {
 	client := &Client{}
 
-	err := core.RequireFeatures(ctx, func(dispatcher routing.Dispatcher, fd dns.FakeDNSEngine) error {
+	var fd dns.FakeDNSEngine
+	err := core.RequireFeatures(ctx, func(dispatcher routing.Dispatcher) error {
+		core.RequireFeatures(ctx, func(fdns dns.FakeDNSEngine) { // FakeDNSEngine is optional
+			fd = fdns
+		})
 		// Create a new server for each client for now
 		server, err := NewServer(ns.Address.AsDestination(), dispatcher, ns.GetQueryStrategy(), fd)
 		if err != nil {
diff --git a/app/dns/nameserver_fakedns.go b/app/dns/nameserver_fakedns.go
index 4b9d93f9..ae7a1a7d 100644
--- a/app/dns/nameserver_fakedns.go
+++ b/app/dns/nameserver_fakedns.go
@@ -21,6 +21,10 @@ func (FakeDNSServer) Name() string {
 }
 
 func (f *FakeDNSServer) QueryIP(ctx context.Context, domain string, _ net.IP, opt dns.IPOption, _ bool) ([]net.IP, error) {
+	if f.fakeDNSEngine == nil {
+		return nil, errors.New("Unable to locate a fake DNS Engine").AtError()
+	}
+
 	var ips []net.Address
 	if fkr0, ok := f.fakeDNSEngine.(dns.FakeDNSEngineRev0); ok {
 		ips = fkr0.GetFakeIPForDomain3(domain, opt.IPv4Enable, opt.IPv6Enable)
diff --git a/proxy/dns/dns.go b/proxy/dns/dns.go
index ed063197..790c80c1 100644
--- a/proxy/dns/dns.go
+++ b/proxy/dns/dns.go
@@ -27,7 +27,7 @@ func init() {
 	common.Must(common.RegisterConfig((*Config)(nil), func(ctx context.Context, config interface{}) (interface{}, error) {
 		h := new(Handler)
 		if err := core.RequireFeatures(ctx, func(dnsClient dns.Client, policyManager policy.Manager) error {
-			core.RequireFeatures(ctx, func(fdns dns.FakeDNSEngine) {
+			core.RequireFeatures(ctx, func(fdns dns.FakeDNSEngine) { // FakeDNSEngine is optional
 				h.fdns = fdns
 			})
 			return h.Init(config.(*Config), dnsClient, policyManager)