From 09426dcd3626eb66fb4709952330d766a324bf9e Mon Sep 17 00:00:00 2001
From: Cuong Manh Le <cuong@windscribe.com>
Date: Thu, 5 Dec 2024 17:06:06 +0700
Subject: [PATCH] cmd/cli: new flow for LAN hostname query

If there is no explicit rules for LAN hostname queries, using OS
resolver instead of forwarding requests to remote upstreams.
---
 cmd/cli/dns_proxy.go      | 10 ++++++----
 cmd/cli/dns_proxy_test.go |  3 +++
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/cmd/cli/dns_proxy.go b/cmd/cli/dns_proxy.go
index f195f62..a69f5b5 100644
--- a/cmd/cli/dns_proxy.go
+++ b/cmd/cli/dns_proxy.go
@@ -456,7 +456,7 @@ func (p *prog) proxy(ctx context.Context, req *proxyRequest) *proxyResponse {
 				res.clientInfo = true
 				return res
 			}
-			upstreams, upstreamConfigs = p.upstreamsAndUpstreamConfigForLanAndPtr(upstreams, upstreamConfigs)
+			upstreams, upstreamConfigs = p.upstreamsAndUpstreamConfigForPtr(upstreams, upstreamConfigs)
 			ctrld.Log(ctx, mainLog.Load().Debug(), "private PTR lookup, using upstreams: %v", upstreams)
 		case isLanHostnameQuery(req.msg):
 			isLanOrPtrQuery = true
@@ -465,7 +465,8 @@ func (p *prog) proxy(ctx context.Context, req *proxyRequest) *proxyResponse {
 				res.clientInfo = true
 				return res
 			}
-			upstreams, upstreamConfigs = p.upstreamsAndUpstreamConfigForLanAndPtr(upstreams, upstreamConfigs)
+			upstreams = []string{upstreamOS}
+			upstreamConfigs = []*ctrld.UpstreamConfig{osUpstreamConfig}
 			ctrld.Log(ctx, mainLog.Load().Debug(), "lan hostname lookup, using upstreams: %v", upstreams)
 		default:
 			ctrld.Log(ctx, mainLog.Load().Debug(), "no explicit policy matched, using default routing -> %v", upstreams)
@@ -605,7 +606,7 @@ func (p *prog) proxy(ctx context.Context, req *proxyRequest) *proxyResponse {
 	return res
 }
 
-func (p *prog) upstreamsAndUpstreamConfigForLanAndPtr(upstreams []string, upstreamConfigs []*ctrld.UpstreamConfig) ([]string, []*ctrld.UpstreamConfig) {
+func (p *prog) upstreamsAndUpstreamConfigForPtr(upstreams []string, upstreamConfigs []*ctrld.UpstreamConfig) ([]string, []*ctrld.UpstreamConfig) {
 	if len(p.localUpstreams) > 0 {
 		tmp := make([]string, 0, len(p.localUpstreams)+len(upstreams))
 		tmp = append(tmp, p.localUpstreams...)
@@ -1060,7 +1061,8 @@ func isLanHostnameQuery(m *dns.Msg) bool {
 	name := strings.TrimSuffix(q.Name, ".")
 	return !strings.Contains(name, ".") ||
 		strings.HasSuffix(name, ".domain") ||
-		strings.HasSuffix(name, ".lan")
+		strings.HasSuffix(name, ".lan") ||
+		strings.HasSuffix(name, ".local")
 }
 
 // isSrvLookup reports whether DNS message is a SRV query.
diff --git a/cmd/cli/dns_proxy_test.go b/cmd/cli/dns_proxy_test.go
index 6e7a431..9deb9ed 100644
--- a/cmd/cli/dns_proxy_test.go
+++ b/cmd/cli/dns_proxy_test.go
@@ -365,6 +365,9 @@ func Test_isLanHostnameQuery(t *testing.T) {
 		{"A not LAN", newDnsMsgWithHostname("example.com", dns.TypeA), false},
 		{"AAAA not LAN", newDnsMsgWithHostname("example.com", dns.TypeAAAA), false},
 		{"Not A or AAAA", newDnsMsgWithHostname("foo", dns.TypeTXT), false},
+		{".domain", newDnsMsgWithHostname("foo.domain", dns.TypeA), true},
+		{".lan", newDnsMsgWithHostname("foo.lan", dns.TypeA), true},
+		{".local", newDnsMsgWithHostname("foo.local", dns.TypeA), true},
 	}
 	for _, tc := range tests {
 		tc := tc