From 3fe85449a9833bc38e897e1dfc38784711b6472d Mon Sep 17 00:00:00 2001
From: Jim Han <50871214+JimhHan@users.noreply.github.com>
Date: Sun, 14 Mar 2021 23:58:27 +0800
Subject: [PATCH] Use 198.18.0.0/16 as default Fake IP Pool (#377)

---
 app/dns/fakedns/fake.go         |  2 +-
 app/dns/fakedns/fakedns_test.go | 13 +++++++++----
 features/dns/fakedns.go         |  2 ++
 infra/conf/fakedns.go           |  3 ++-
 4 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/app/dns/fakedns/fake.go b/app/dns/fakedns/fake.go
index b4a986a5..5d3965e4 100644
--- a/app/dns/fakedns/fake.go
+++ b/app/dns/fakedns/fake.go
@@ -41,7 +41,7 @@ func NewFakeDNSHolder() (*Holder, error) {
 	if fkdns, err = NewFakeDNSHolderConfigOnly(nil); err != nil {
 		return nil, newError("Unable to create Fake Dns Engine").Base(err).AtError()
 	}
-	err = fkdns.initialize("240.0.0.0/8", 65535)
+	err = fkdns.initialize(dns.FakeIPPool, 65535)
 	if err != nil {
 		return nil, err
 	}
diff --git a/app/dns/fakedns/fakedns_test.go b/app/dns/fakedns/fakedns_test.go
index b0812f62..74106171 100644
--- a/app/dns/fakedns/fakedns_test.go
+++ b/app/dns/fakedns/fakedns_test.go
@@ -8,6 +8,11 @@ import (
 	"github.com/xtls/xray-core/common"
 	"github.com/xtls/xray-core/common/net"
 	"github.com/xtls/xray-core/common/uuid"
+	"github.com/xtls/xray-core/features/dns"
+)
+
+var (
+	ipPrefix = "198.18."
 )
 
 func TestNewFakeDnsHolder(_ *testing.T) {
@@ -20,7 +25,7 @@ func TestFakeDnsHolderCreateMapping(t *testing.T) {
 	common.Must(err)
 
 	addr := fkdns.GetFakeIPForDomain("fakednstest.example.com")
-	assert.Equal(t, "240.", addr[0].IP().String()[0:4])
+	assert.Equal(t, ipPrefix, addr[0].IP().String()[0:len(ipPrefix)])
 }
 
 func TestFakeDnsHolderCreateMappingMany(t *testing.T) {
@@ -28,10 +33,10 @@ func TestFakeDnsHolderCreateMappingMany(t *testing.T) {
 	common.Must(err)
 
 	addr := fkdns.GetFakeIPForDomain("fakednstest.example.com")
-	assert.Equal(t, "240.", addr[0].IP().String()[0:4])
+	assert.Equal(t, ipPrefix, addr[0].IP().String()[0:len(ipPrefix)])
 
 	addr2 := fkdns.GetFakeIPForDomain("fakednstest2.example.com")
-	assert.Equal(t, "240.", addr2[0].IP().String()[0:4])
+	assert.Equal(t, ipPrefix, addr2[0].IP().String()[0:len(ipPrefix)])
 	assert.NotEqual(t, addr[0].IP().String(), addr2[0].IP().String())
 }
 
@@ -64,7 +69,7 @@ func TestFakeDnsHolderCreateMappingManySingleDomain(t *testing.T) {
 
 func TestFakeDnsHolderCreateMappingAndRollOver(t *testing.T) {
 	fkdns, err := NewFakeDNSHolderConfigOnly(&FakeDnsPool{
-		IpPool:  "240.0.0.0/12",
+		IpPool:  dns.FakeIPPool,
 		LruSize: 256,
 	})
 	common.Must(err)
diff --git a/features/dns/fakedns.go b/features/dns/fakedns.go
index f0755bfd..12a7b41d 100644
--- a/features/dns/fakedns.go
+++ b/features/dns/fakedns.go
@@ -13,3 +13,5 @@ type FakeDNSEngine interface {
 	GetDomainFromFakeDNS(ip net.Address) string
 	GetFakeIPRange() *gonet.IPNet
 }
+
+var FakeIPPool = "198.18.0.0/16"
diff --git a/infra/conf/fakedns.go b/infra/conf/fakedns.go
index 47fc62dc..a047ee9f 100644
--- a/infra/conf/fakedns.go
+++ b/infra/conf/fakedns.go
@@ -3,6 +3,7 @@ package conf
 import (
 	"github.com/golang/protobuf/proto"
 	"github.com/xtls/xray-core/app/dns/fakedns"
+	"github.com/xtls/xray-core/features/dns"
 )
 
 type FakeDNSConfig struct {
@@ -36,7 +37,7 @@ func (FakeDNSPostProcessingStage) Process(conf *Config) error {
 		if conf.FakeDNS == nil {
 			// Add a Fake DNS Config if there is none
 			conf.FakeDNS = &FakeDNSConfig{
-				IPPool:  "240.0.0.0/8",
+				IPPool:  dns.FakeIPPool,
 				LruSize: 65535,
 			}
 		}