add cache size option

cmd/tun2socks/main.go

@@ -50,6 +50,7 @@ type CmdArgs struct {
 	FakeIPRange          *string
 	FakeDnsAddr          *string
 	FakeDnsHosts         *string
+	DnsCacheSize         *int
 	ExceptionApps        *string
 	ExceptionSendThrough *string
 	Stats                *bool

cmd/tun2socks/main_fakedns.go

@@ -13,10 +13,11 @@ func init() {
 	args.FakeDnsAddr = flag.String("fakeDnsAddr", ":53", "listen address of fake DNS")
 	args.FakeIPRange = flag.String("fakeIPRange", "198.18.0.1/16", "fake IP CIDR range for DNS")
 	args.FakeDnsHosts = flag.String("fakeDnsHosts", "", "Hosts mapping, e.g. 'a.com=1.1.1.1,b.net=2.2.2.2'")
+	args.DnsCacheSize = flag.Int("dnsCacheSize", 100, "Size of DNS LRU Cache")
 
 	addPostFlagsInitFn(func() {
 		if *args.EnableFakeDns {
-			fakeDnsServer, err := fakedns.NewServer(*args.FakeIPRange, *args.FakeDnsHosts)
+			fakeDnsServer, err := fakedns.NewServer(*args.FakeIPRange, *args.FakeDnsHosts, *args.DnsCacheSize)
 			if err != nil {
 				panic("create fake dns server error")
 			}

common/dns/fakedns/server.go

@@ -9,8 +9,6 @@ import (
 )
 
 const (
-	lruCacheSize = 1000
-
 	dnsFakeTTL    uint32 = 1
 	dnsDefaultTTL uint32 = 600
 )
@@ -56,12 +54,12 @@ func (s *Server) IPToHost(ip net.IP) (string, bool) {
 	return s.p.LookBack(ip)
 }
 
-func NewServer(fakeIPRange, hostsLine string) (*Server, error) {
+func NewServer(fakeIPRange, hostsLine string, size int) (*Server, error) {
 	_, ipnet, err := net.ParseCIDR(fakeIPRange)
 	if err != nil {
 		return nil, err
 	}
-	pool, err := fakeip.New(ipnet, lruCacheSize)
+	pool, err := fakeip.New(ipnet, size)
 	if err != nil {
 		return nil, err
 	}