From 414bfa8b1020dd91dcd349e9bb9506d77f9d6b18 Mon Sep 17 00:00:00 2001
From: k9982874 <k9982874@gmail.com>
Date: Mon, 10 Mar 2025 13:57:59 +0800
Subject: [PATCH] Fix hosts DNS server

---
 dns/client.go                     |  4 ++--
 dns/transport/hosts/hosts.go      | 20 +++++++++++++++++---
 dns/transport/hosts/hosts_file.go |  2 +-
 dns/transport/hosts/hosts_test.go |  4 ++--
 option/dns.go                     |  4 ++--
 5 files changed, 24 insertions(+), 10 deletions(-)

diff --git a/dns/client.go b/dns/client.go
index d44883b5..f456f878 100644
--- a/dns/client.go
+++ b/dns/client.go
@@ -537,7 +537,7 @@ func FixedResponse(id uint16, question dns.Question, addresses []netip.Addr, tim
 		Question: []dns.Question{question},
 	}
 	for _, address := range addresses {
-		if address.Is4() {
+		if address.Is4() && question.Qtype == dns.TypeA {
 			response.Answer = append(response.Answer, &dns.A{
 				Hdr: dns.RR_Header{
 					Name:   question.Name,
@@ -547,7 +547,7 @@ func FixedResponse(id uint16, question dns.Question, addresses []netip.Addr, tim
 				},
 				A: address.AsSlice(),
 			})
-		} else {
+		} else if address.Is6() && question.Qtype == dns.TypeAAAA {
 			response.Answer = append(response.Answer, &dns.AAAA{
 				Hdr: dns.RR_Header{
 					Name:   question.Name,
diff --git a/dns/transport/hosts/hosts.go b/dns/transport/hosts/hosts.go
index 773a1d2a..0a1dd395 100644
--- a/dns/transport/hosts/hosts.go
+++ b/dns/transport/hosts/hosts.go
@@ -2,6 +2,7 @@ package hosts
 
 import (
 	"context"
+	"net/netip"
 	"os"
 
 	"github.com/sagernet/sing-box/adapter"
@@ -22,11 +23,15 @@ var _ adapter.DNSTransport = (*Transport)(nil)
 
 type Transport struct {
 	dns.TransportAdapter
-	files []*File
+	files      []*File
+	predefined map[string][]netip.Addr
 }
 
 func NewTransport(ctx context.Context, logger log.ContextLogger, tag string, options option.HostsDNSServerOptions) (adapter.DNSTransport, error) {
-	var files []*File
+	var (
+		files      []*File
+		predefined = make(map[string][]netip.Addr)
+	)
 	if len(options.Path) == 0 {
 		files = append(files, NewFile(DefaultPath))
 	} else {
@@ -34,9 +39,15 @@ func NewTransport(ctx context.Context, logger log.ContextLogger, tag string, opt
 			files = append(files, NewFile(filemanager.BasePath(ctx, os.ExpandEnv(path))))
 		}
 	}
+	if options.Predefined != nil {
+		for _, entry := range options.Predefined.Entries() {
+			predefined[mDNS.CanonicalName(entry.Key)] = entry.Value
+		}
+	}
 	return &Transport{
 		TransportAdapter: dns.NewTransportAdapter(C.DNSTypeHosts, tag, nil),
 		files:            files,
+		predefined:       predefined,
 	}, nil
 }
 
@@ -45,8 +56,11 @@ func (t *Transport) Reset() {
 
 func (t *Transport) Exchange(ctx context.Context, message *mDNS.Msg) (*mDNS.Msg, error) {
 	question := message.Question[0]
-	domain := dns.FqdnToDomain(question.Name)
+	domain := mDNS.CanonicalName(question.Name)
 	if question.Qtype == mDNS.TypeA || question.Qtype == mDNS.TypeAAAA {
+		if addresses, ok := t.predefined[domain]; ok {
+			return dns.FixedResponse(message.Id, question, addresses, C.DefaultDNSTTL), nil
+		}
 		for _, file := range t.files {
 			addresses := file.Lookup(domain)
 			if len(addresses) > 0 {
diff --git a/dns/transport/hosts/hosts_file.go b/dns/transport/hosts/hosts_file.go
index 7ff34f69..ec384882 100644
--- a/dns/transport/hosts/hosts_file.go
+++ b/dns/transport/hosts/hosts_file.go
@@ -34,7 +34,7 @@ func (f *File) Lookup(name string) []netip.Addr {
 	f.access.Lock()
 	defer f.access.Unlock()
 	f.update()
-	return f.byName[name]
+	return f.byName[dns.CanonicalName(name)]
 }
 
 func (f *File) update() {
diff --git a/dns/transport/hosts/hosts_test.go b/dns/transport/hosts/hosts_test.go
index 944aa437..3ae160b7 100644
--- a/dns/transport/hosts/hosts_test.go
+++ b/dns/transport/hosts/hosts_test.go
@@ -11,6 +11,6 @@ import (
 
 func TestHosts(t *testing.T) {
 	t.Parallel()
-	require.Equal(t, []netip.Addr{netip.AddrFrom4([4]byte{127, 0, 0, 1}), netip.IPv6Loopback()}, hosts.NewFile("testdata/hosts").Lookup("localhost."))
-	require.NotEmpty(t, hosts.NewFile(hosts.DefaultPath).Lookup("localhost."))
+	require.Equal(t, []netip.Addr{netip.AddrFrom4([4]byte{127, 0, 0, 1}), netip.IPv6Loopback()}, hosts.NewFile("testdata/hosts").Lookup("localhost"))
+	require.NotEmpty(t, hosts.NewFile(hosts.DefaultPath).Lookup("localhost"))
 }
diff --git a/option/dns.go b/option/dns.go
index 64dbea38..04eb442d 100644
--- a/option/dns.go
+++ b/option/dns.go
@@ -316,8 +316,8 @@ type LegacyDNSServerOptions struct {
 }
 
 type HostsDNSServerOptions struct {
-	Path       badoption.Listable[string]                               `json:"path,omitempty"`
-	Predefined badjson.TypedMap[string, badoption.Listable[netip.Addr]] `json:"predefined,omitempty"`
+	Path       badoption.Listable[string]                                `json:"path,omitempty"`
+	Predefined *badjson.TypedMap[string, badoption.Listable[netip.Addr]] `json:"predefined,omitempty"`
 }
 
 type LocalDNSServerOptions struct {