socks: Add custom udp listener

common/bufio/copy_direct_windows.go

@@ -120,16 +120,16 @@ func (w *syscallPacketReadWaiter) InitializeReadWaiter(options N.ReadWaitOptions
 		var readN int
 		var from windows.Sockaddr
 		readN, from, w.readErr = windows.Recvfrom(windows.Handle(fd), buffer.FreeBytes(), 0)
+		//goland:noinspection GoDirectComparisonOfErrors
+		if w.readErr != nil {
+			buffer.Release()
+			return w.readErr != windows.WSAEWOULDBLOCK
+		}
 		if readN > 0 {
 			buffer.Truncate(readN)
-			w.options.PostReturn(buffer)
-			w.buffer = buffer
-		} else {
-			buffer.Release()
-		}
-		if w.readErr == windows.WSAEWOULDBLOCK {
-			return false
 		}
+		w.options.PostReturn(buffer)
+		w.buffer = buffer
 		if from != nil {
 			switch fromAddr := from.(type) {
 			case *windows.SockaddrInet4:

common/bufio/nat.go

@@ -30,6 +30,14 @@ func NewNATPacketConn(conn N.NetPacketConn, origin M.Socksaddr, destination M.So
 	}
 }
 
+func NewDestinationNATPacketConn(conn N.NetPacketConn, origin M.Socksaddr, destination M.Socksaddr) NATPacketConn {
+	return &destinationNATPacketConn{
+		NetPacketConn: conn,
+		origin:        origin,
+		destination:   destination,
+	}
+}
+
 type unidirectionalNATPacketConn struct {
 	N.NetPacketConn
 	origin      M.Socksaddr
@@ -144,6 +152,60 @@ func (c *bidirectionalNATPacketConn) RemoteAddr() net.Addr {
 	return c.destination.UDPAddr()
 }
 
+type destinationNATPacketConn struct {
+	N.NetPacketConn
+	origin      M.Socksaddr
+	destination M.Socksaddr
+}
+
+func (c *destinationNATPacketConn) ReadFrom(p []byte) (n int, addr net.Addr, err error) {
+	n, addr, err = c.NetPacketConn.ReadFrom(p)
+	if err != nil {
+		return
+	}
+	if M.SocksaddrFromNet(addr) == c.origin {
+		addr = c.destination.UDPAddr()
+	}
+	return
+}
+
+func (c *destinationNATPacketConn) WriteTo(p []byte, addr net.Addr) (n int, err error) {
+	if M.SocksaddrFromNet(addr) == c.destination {
+		addr = c.origin.UDPAddr()
+	}
+	return c.NetPacketConn.WriteTo(p, addr)
+}
+
+func (c *destinationNATPacketConn) ReadPacket(buffer *buf.Buffer) (destination M.Socksaddr, err error) {
+	destination, err = c.NetPacketConn.ReadPacket(buffer)
+	if err != nil {
+		return
+	}
+	if destination == c.origin {
+		destination = c.destination
+	}
+	return
+}
+
+func (c *destinationNATPacketConn) WritePacket(buffer *buf.Buffer, destination M.Socksaddr) error {
+	if destination == c.destination {
+		destination = c.origin
+	}
+	return c.NetPacketConn.WritePacket(buffer, destination)
+}
+
+func (c *destinationNATPacketConn) UpdateDestination(destinationAddress netip.Addr) {
+	c.destination = M.SocksaddrFrom(destinationAddress, c.destination.Port)
+}
+
+func (c *destinationNATPacketConn) Upstream() any {
+	return c.NetPacketConn
+}
+
+func (c *destinationNATPacketConn) RemoteAddr() net.Addr {
+	return c.destination.UDPAddr()
+}
+
 func socksaddrWithoutPort(destination M.Socksaddr) M.Socksaddr {
 	destination.Port = 0
 	return destination

common/exceptions/error.go

@@ -40,11 +40,11 @@ func Extend(cause error, message ...any) error {
 }
 
 func IsClosedOrCanceled(err error) bool {
-	return IsMulti(err, io.EOF, net.ErrClosed, io.ErrClosedPipe, os.ErrClosed, syscall.EPIPE, syscall.ECONNRESET, context.Canceled, context.DeadlineExceeded) || IsTimeout(err)
+	return IsClosed(err) || IsCanceled(err) || IsTimeout(err)
 }
 
 func IsClosed(err error) bool {
-	return IsMulti(err, io.EOF, net.ErrClosed, io.ErrClosedPipe, os.ErrClosed, syscall.EPIPE, syscall.ECONNRESET)
+	return IsMulti(err, io.EOF, net.ErrClosed, io.ErrClosedPipe, os.ErrClosed, syscall.EPIPE, syscall.ECONNRESET, syscall.ENOTCONN)
 }
 
 func IsCanceled(err error) bool {

common/json/badjson/merge_objects.go

@@ -2,9 +2,11 @@ package badjson
 
 import (
 	"context"
+	"reflect"
 
 	E "github.com/sagernet/sing/common/exceptions"
 	"github.com/sagernet/sing/common/json"
+	cJSON "github.com/sagernet/sing/common/json/internal/contextjson"
 )
 
 func MarshallObjects(objects ...any) ([]byte, error) {
@@ -31,16 +33,12 @@ func UnmarshallExcluded(inputContent []byte, parentObject any, object any) error
 }
 
 func UnmarshallExcludedContext(ctx context.Context, inputContent []byte, parentObject any, object any) error {
-	parentContent, err := newJSONObject(ctx, parentObject)
-	if err != nil {
-		return err
-	}
 	var content JSONObject
-	err = content.UnmarshalJSONContext(ctx, inputContent)
+	err := content.UnmarshalJSONContext(ctx, inputContent)
 	if err != nil {
 		return err
 	}
-	for _, key := range parentContent.Keys() {
+	for _, key := range cJSON.ObjectKeys(reflect.TypeOf(parentObject)) {
 		content.Remove(key)
 	}
 	if object == nil {

common/json/badoption/listable.go

@@ -18,6 +18,9 @@ func (l Listable[T]) MarshalJSONContext(ctx context.Context) ([]byte, error) {
 }
 
 func (l *Listable[T]) UnmarshalJSONContext(ctx context.Context, content []byte) error {
+	if string(content) == "null" {
+		return nil
+	}
 	var singleItem T
 	err := json.UnmarshalContextDisallowUnknownFields(ctx, content, &singleItem)
 	if err == nil {

common/json/internal/contextjson/keys.go

@@ -0,0 +1,20 @@
+package json
+
+import (
+	"reflect"
+
+	"github.com/sagernet/sing/common"
+)
+
+func ObjectKeys(object reflect.Type) []string {
+	switch object.Kind() {
+	case reflect.Pointer:
+		return ObjectKeys(object.Elem())
+	case reflect.Struct:
+	default:
+		panic("invalid non-struct input")
+	}
+	return common.Map(cachedTypeFields(object).list, func(field field) string {
+		return field.name
+	})
+}

common/json/internal/contextjson/keys_test.go

@@ -0,0 +1,26 @@
+package json_test
+
+import (
+	"reflect"
+	"testing"
+
+	json "github.com/sagernet/sing/common/json/internal/contextjson"
+
+	"github.com/stretchr/testify/require"
+)
+
+type MyObject struct {
+	Hello string `json:"hello,omitempty"`
+	MyWorld
+	MyWorld2 string `json:"-"`
+}
+
+type MyWorld struct {
+	World string `json:"world,omitempty"`
+}
+
+func TestObjectKeys(t *testing.T) {
+	t.Parallel()
+	keys := json.ObjectKeys(reflect.TypeOf(&MyObject{}))
+	require.Equal(t, []string{"hello", "world"}, keys)
+}

common/ntp/time_windows.go

@@ -7,6 +7,7 @@ import (
 )
 
 func SetSystemTime(nowTime time.Time) error {
+	nowTime = nowTime.UTC()
 	var systemTime windows.Systemtime
 	systemTime.Year = uint16(nowTime.Year())
 	systemTime.Month = uint16(nowTime.Month())

common/udpnat2/conn.go

@@ -28,6 +28,7 @@ type natConn struct {
 	cache           freelru.Cache[netip.AddrPort, *natConn]
 	writer          N.PacketWriter
 	localAddr       M.Socksaddr
+	handlerAccess   sync.RWMutex
 	handler         N.UDPHandlerEx
 	packetChan      chan *N.PacketBuffer
 	closeOnce       sync.Once
@@ -75,12 +76,10 @@ func (c *natConn) WaitReadPacket() (buffer *buf.Buffer, destination M.Socksaddr,
 }
 
 func (c *natConn) SetHandler(handler N.UDPHandlerEx) {
-	select {
-	case <-c.doneChan:
-	default:
-	}
+	c.handlerAccess.Lock()
 	c.handler = handler
 	c.readWaitOptions = N.NewReadWaitOptions(c.writer, handler)
+	c.handlerAccess.Unlock()
 fetch:
 	for {
 		select {

common/udpnat2/service.go

@@ -27,7 +27,7 @@ func New(handler N.UDPConnectionHandlerEx, prepare PrepareFunc, timeout time.Dur
 	}
 	var cache freelru.Cache[netip.AddrPort, *natConn]
 	if !shared {
-		cache = common.Must1(freelru.New[netip.AddrPort, *natConn](1024, maphash.NewHasher[netip.AddrPort]().Hash32))
+		cache = common.Must1(freelru.NewSynced[netip.AddrPort, *natConn](1024, maphash.NewHasher[netip.AddrPort]().Hash32))
 	} else {
 		cache = common.Must1(freelru.NewSharded[netip.AddrPort, *natConn](1024, maphash.NewHasher[netip.AddrPort]().Hash32))
 	}
@@ -51,7 +51,7 @@ func New(handler N.UDPConnectionHandlerEx, prepare PrepareFunc, timeout time.Dur
 }
 
 func (s *Service) NewPacket(bufferSlices [][]byte, source M.Socksaddr, destination M.Socksaddr, userData any) {
-	conn, loaded := s.cache.GetAndRefreshOrAdd(source.AddrPort(), func() (*natConn, bool) {
+	conn, _, ok := s.cache.GetAndRefreshOrAdd(source.AddrPort(), func() (*natConn, bool) {
 		ok, ctx, writer, onClose := s.prepare(source, destination, userData)
 		if !ok {
 			return nil, false
@@ -67,17 +67,18 @@ func (s *Service) NewPacket(bufferSlices [][]byte, source M.Socksaddr, destinati
 		go s.handler.NewPacketConnectionEx(ctx, newConn, source, destination, onClose)
 		return newConn, true
 	})
-	if !loaded {
-		if conn == nil {
-			return
-		}
+	if !ok {
+		return
 	}
 	buffer := conn.readWaitOptions.NewPacketBuffer()
 	for _, bufferSlice := range bufferSlices {
 		buffer.Write(bufferSlice)
 	}
-	if conn.handler != nil {
-		conn.handler.NewPacketEx(buffer, destination)
+	conn.handlerAccess.RLock()
+	handler := conn.handler
+	conn.handlerAccess.RUnlock()
+	if handler != nil {
+		handler.NewPacketEx(buffer, destination)
 		return
 	}
 	packet := N.NewPacketBuffer()

common/windnsapi/dnsapi_test.go

@@ -1,16 +1,14 @@
+//go:build windows
+
 package windnsapi
 
 import (
-	"runtime"
 	"testing"
 
 	"github.com/stretchr/testify/require"
 )
 
 func TestDNSAPI(t *testing.T) {
-	if runtime.GOOS != "windows" {
-		t.SkipNow()
-	}
 	t.Parallel()
 	require.NoError(t, FlushResolverCache())
 }

common/winiphlpapi/helper.go

@@ -0,0 +1,217 @@
+//go:build windows
+
+package winiphlpapi
+
+import (
+	"context"
+	"encoding/binary"
+	"net"
+	"net/netip"
+	"os"
+	"time"
+	"unsafe"
+
+	E "github.com/sagernet/sing/common/exceptions"
+	M "github.com/sagernet/sing/common/metadata"
+	N "github.com/sagernet/sing/common/network"
+)
+
+func LoadEStats() error {
+	err := modiphlpapi.Load()
+	if err != nil {
+		return err
+	}
+	err = procGetTcpTable.Find()
+	if err != nil {
+		return err
+	}
+	err = procGetTcp6Table.Find()
+	if err != nil {
+		return err
+	}
+	err = procGetPerTcp6ConnectionEStats.Find()
+	if err != nil {
+		return err
+	}
+	err = procGetPerTcp6ConnectionEStats.Find()
+	if err != nil {
+		return err
+	}
+	err = procSetPerTcpConnectionEStats.Find()
+	if err != nil {
+		return err
+	}
+	err = procSetPerTcp6ConnectionEStats.Find()
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+func LoadExtendedTable() error {
+	err := modiphlpapi.Load()
+	if err != nil {
+		return err
+	}
+	err = procGetExtendedTcpTable.Find()
+	if err != nil {
+		return err
+	}
+	err = procGetExtendedUdpTable.Find()
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+func FindPid(network string, source netip.AddrPort) (uint32, error) {
+	switch N.NetworkName(network) {
+	case N.NetworkTCP:
+		if source.Addr().Is4() {
+			tcpTable, err := GetExtendedTcpTable()
+			if err != nil {
+				return 0, err
+			}
+			for _, row := range tcpTable {
+				if source == netip.AddrPortFrom(DwordToAddr(row.DwLocalAddr), DwordToPort(row.DwLocalPort)) {
+					return row.DwOwningPid, nil
+				}
+			}
+		} else {
+			tcpTable, err := GetExtendedTcp6Table()
+			if err != nil {
+				return 0, err
+			}
+			for _, row := range tcpTable {
+				if source == netip.AddrPortFrom(netip.AddrFrom16(row.UcLocalAddr), DwordToPort(row.DwLocalPort)) {
+					return row.DwOwningPid, nil
+				}
+			}
+		}
+	case N.NetworkUDP:
+		if source.Addr().Is4() {
+			udpTable, err := GetExtendedUdpTable()
+			if err != nil {
+				return 0, err
+			}
+			for _, row := range udpTable {
+				if source == netip.AddrPortFrom(DwordToAddr(row.DwLocalAddr), DwordToPort(row.DwLocalPort)) {
+					return row.DwOwningPid, nil
+				}
+			}
+		} else {
+			udpTable, err := GetExtendedUdp6Table()
+			if err != nil {
+				return 0, err
+			}
+			for _, row := range udpTable {
+				if source == netip.AddrPortFrom(netip.AddrFrom16(row.UcLocalAddr), DwordToPort(row.DwLocalPort)) {
+					return row.DwOwningPid, nil
+				}
+			}
+		}
+	}
+	return 0, E.New("process not found for ", source)
+}
+
+func WriteAndWaitAck(ctx context.Context, conn net.Conn, payload []byte) error {
+	source := M.AddrPortFromNet(conn.LocalAddr())
+	destination := M.AddrPortFromNet(conn.RemoteAddr())
+	if source.Addr().Is4() {
+		tcpTable, err := GetTcpTable()
+		if err != nil {
+			return err
+		}
+		var tcpRow *MibTcpRow
+		for _, row := range tcpTable {
+			if source == netip.AddrPortFrom(DwordToAddr(row.DwLocalAddr), DwordToPort(row.DwLocalPort)) ||
+				destination == netip.AddrPortFrom(DwordToAddr(row.DwRemoteAddr), DwordToPort(row.DwRemotePort)) {
+				tcpRow = &row
+				break
+			}
+		}
+		if tcpRow == nil {
+			return E.New("row not found for: ", source)
+		}
+		err = SetPerTcpConnectionEStatsSendBuffer(tcpRow, &TcpEstatsSendBuffRwV0{
+			EnableCollection: true,
+		})
+		if err != nil {
+			return os.NewSyscallError("SetPerTcpConnectionEStatsSendBufferV0", err)
+		}
+		defer SetPerTcpConnectionEStatsSendBuffer(tcpRow, &TcpEstatsSendBuffRwV0{
+			EnableCollection: false,
+		})
+		_, err = conn.Write(payload)
+		if err != nil {
+			return err
+		}
+		for {
+			select {
+			case <-ctx.Done():
+				return ctx.Err()
+			default:
+			}
+			eStstsSendBuffer, err := GetPerTcpConnectionEStatsSendBuffer(tcpRow)
+			if err != nil {
+				return err
+			}
+			if eStstsSendBuffer.CurRetxQueue == 0 {
+				return nil
+			}
+			time.Sleep(10 * time.Millisecond)
+		}
+	} else {
+		tcpTable, err := GetTcp6Table()
+		if err != nil {
+			return err
+		}
+		var tcpRow *MibTcp6Row
+		for _, row := range tcpTable {
+			if source == netip.AddrPortFrom(netip.AddrFrom16(row.LocalAddr), DwordToPort(row.LocalPort)) ||
+				destination == netip.AddrPortFrom(netip.AddrFrom16(row.RemoteAddr), DwordToPort(row.RemotePort)) {
+				tcpRow = &row
+				break
+			}
+		}
+		if tcpRow == nil {
+			return E.New("row not found for: ", source)
+		}
+		err = SetPerTcp6ConnectionEStatsSendBuffer(tcpRow, &TcpEstatsSendBuffRwV0{
+			EnableCollection: true,
+		})
+		if err != nil {
+			return os.NewSyscallError("SetPerTcpConnectionEStatsSendBufferV0", err)
+		}
+		defer SetPerTcp6ConnectionEStatsSendBuffer(tcpRow, &TcpEstatsSendBuffRwV0{
+			EnableCollection: false,
+		})
+		_, err = conn.Write(payload)
+		if err != nil {
+			return err
+		}
+		for {
+			select {
+			case <-ctx.Done():
+				return ctx.Err()
+			default:
+			}
+			eStstsSendBuffer, err := GetPerTcp6ConnectionEStatsSendBuffer(tcpRow)
+			if err != nil {
+				return err
+			}
+			if eStstsSendBuffer.CurRetxQueue == 0 {
+				return nil
+			}
+			time.Sleep(10 * time.Millisecond)
+		}
+	}
+}
+
+func DwordToAddr(addr uint32) netip.Addr {
+	return netip.AddrFrom4(*(*[4]byte)(unsafe.Pointer(&addr)))
+}
+
+func DwordToPort(dword uint32) uint16 {
+	return binary.BigEndian.Uint16((*[4]byte)(unsafe.Pointer(&dword))[:])
+}

common/winiphlpapi/iphlpapi.go

@@ -0,0 +1,313 @@
+//go:build windows
+
+package winiphlpapi
+
+import (
+	"errors"
+	"os"
+	"unsafe"
+
+	"golang.org/x/sys/windows"
+)
+
+const (
+	TcpTableBasicListener uint32 = iota
+	TcpTableBasicConnections
+	TcpTableBasicAll
+	TcpTableOwnerPidListener
+	TcpTableOwnerPidConnections
+	TcpTableOwnerPidAll
+	TcpTableOwnerModuleListener
+	TcpTableOwnerModuleConnections
+	TcpTableOwnerModuleAll
+)
+
+const (
+	UdpTableBasic uint32 = iota
+	UdpTableOwnerPid
+	UdpTableOwnerModule
+)
+
+const (
+	TcpConnectionEstatsSynOpts uint32 = iota
+	TcpConnectionEstatsData
+	TcpConnectionEstatsSndCong
+	TcpConnectionEstatsPath
+	TcpConnectionEstatsSendBuff
+	TcpConnectionEstatsRec
+	TcpConnectionEstatsObsRec
+	TcpConnectionEstatsBandwidth
+	TcpConnectionEstatsFineRtt
+	TcpConnectionEstatsMaximum
+)
+
+type MibTcpTable struct {
+	DwNumEntries uint32
+	Table        [1]MibTcpRow
+}
+
+type MibTcpRow struct {
+	DwState      uint32
+	DwLocalAddr  uint32
+	DwLocalPort  uint32
+	DwRemoteAddr uint32
+	DwRemotePort uint32
+}
+
+type MibTcp6Table struct {
+	DwNumEntries uint32
+	Table        [1]MibTcp6Row
+}
+
+type MibTcp6Row struct {
+	State         uint32
+	LocalAddr     [16]byte
+	LocalScopeId  uint32
+	LocalPort     uint32
+	RemoteAddr    [16]byte
+	RemoteScopeId uint32
+	RemotePort    uint32
+}
+
+type MibTcpTableOwnerPid struct {
+	DwNumEntries uint32
+	Table        [1]MibTcpRowOwnerPid
+}
+
+type MibTcpRowOwnerPid struct {
+	DwState      uint32
+	DwLocalAddr  uint32
+	DwLocalPort  uint32
+	DwRemoteAddr uint32
+	DwRemotePort uint32
+	DwOwningPid  uint32
+}
+
+type MibTcp6TableOwnerPid struct {
+	DwNumEntries uint32
+	Table        [1]MibTcp6RowOwnerPid
+}
+
+type MibTcp6RowOwnerPid struct {
+	UcLocalAddr     [16]byte
+	DwLocalScopeId  uint32
+	DwLocalPort     uint32
+	UcRemoteAddr    [16]byte
+	DwRemoteScopeId uint32
+	DwRemotePort    uint32
+	DwState         uint32
+	DwOwningPid     uint32
+}
+
+type MibUdpTableOwnerPid struct {
+	DwNumEntries uint32
+	Table        [1]MibUdpRowOwnerPid
+}
+
+type MibUdpRowOwnerPid struct {
+	DwLocalAddr uint32
+	DwLocalPort uint32
+	DwOwningPid uint32
+}
+
+type MibUdp6TableOwnerPid struct {
+	DwNumEntries uint32
+	Table        [1]MibUdp6RowOwnerPid
+}
+
+type MibUdp6RowOwnerPid struct {
+	UcLocalAddr    [16]byte
+	DwLocalScopeId uint32
+	DwLocalPort    uint32
+	DwOwningPid    uint32
+}
+
+type TcpEstatsSendBufferRodV0 struct {
+	CurRetxQueue uint64
+	MaxRetxQueue uint64
+	CurAppWQueue uint64
+	MaxAppWQueue uint64
+}
+
+type TcpEstatsSendBuffRwV0 struct {
+	EnableCollection bool
+}
+
+const (
+	offsetOfMibTcpTable            = unsafe.Offsetof(MibTcpTable{}.Table)
+	offsetOfMibTcp6Table           = unsafe.Offsetof(MibTcp6Table{}.Table)
+	offsetOfMibTcpTableOwnerPid    = unsafe.Offsetof(MibTcpTableOwnerPid{}.Table)
+	offsetOfMibTcp6TableOwnerPid   = unsafe.Offsetof(MibTcpTableOwnerPid{}.Table)
+	offsetOfMibUdpTableOwnerPid    = unsafe.Offsetof(MibUdpTableOwnerPid{}.Table)
+	offsetOfMibUdp6TableOwnerPid   = unsafe.Offsetof(MibUdp6TableOwnerPid{}.Table)
+	sizeOfTcpEstatsSendBuffRwV0    = unsafe.Sizeof(TcpEstatsSendBuffRwV0{})
+	sizeOfTcpEstatsSendBufferRodV0 = unsafe.Sizeof(TcpEstatsSendBufferRodV0{})
+)
+
+func GetTcpTable() ([]MibTcpRow, error) {
+	var size uint32
+	err := getTcpTable(nil, &size, false)
+	if !errors.Is(err, windows.ERROR_INSUFFICIENT_BUFFER) {
+		return nil, err
+	}
+	for {
+		table := make([]byte, size)
+		err = getTcpTable(&table[0], &size, false)
+		if err != nil {
+			if errors.Is(err, windows.ERROR_INSUFFICIENT_BUFFER) {
+				continue
+			}
+			return nil, err
+		}
+		dwNumEntries := int(*(*uint32)(unsafe.Pointer(&table[0])))
+		return unsafe.Slice((*MibTcpRow)(unsafe.Pointer(&table[offsetOfMibTcpTable])), dwNumEntries), nil
+	}
+}
+
+func GetTcp6Table() ([]MibTcp6Row, error) {
+	var size uint32
+	err := getTcp6Table(nil, &size, false)
+	if !errors.Is(err, windows.ERROR_INSUFFICIENT_BUFFER) {
+		return nil, err
+	}
+	for {
+		table := make([]byte, size)
+		err = getTcp6Table(&table[0], &size, false)
+		if err != nil {
+			if errors.Is(err, windows.ERROR_INSUFFICIENT_BUFFER) {
+				continue
+			}
+			return nil, err
+		}
+		dwNumEntries := int(*(*uint32)(unsafe.Pointer(&table[0])))
+		return unsafe.Slice((*MibTcp6Row)(unsafe.Pointer(&table[offsetOfMibTcp6Table])), dwNumEntries), nil
+	}
+}
+
+func GetExtendedTcpTable() ([]MibTcpRowOwnerPid, error) {
+	var size uint32
+	err := getExtendedTcpTable(nil, &size, false, windows.AF_INET, TcpTableOwnerPidConnections, 0)
+	if !errors.Is(err, windows.ERROR_INSUFFICIENT_BUFFER) {
+		return nil, os.NewSyscallError("GetExtendedTcpTable", err)
+	}
+	for {
+		table := make([]byte, size)
+		err = getExtendedTcpTable(&table[0], &size, false, windows.AF_INET, TcpTableOwnerPidConnections, 0)
+		if err != nil {
+			if errors.Is(err, windows.ERROR_INSUFFICIENT_BUFFER) {
+				continue
+			}
+			return nil, os.NewSyscallError("GetExtendedTcpTable", err)
+		}
+		dwNumEntries := int(*(*uint32)(unsafe.Pointer(&table[0])))
+		return unsafe.Slice((*MibTcpRowOwnerPid)(unsafe.Pointer(&table[offsetOfMibTcpTableOwnerPid])), dwNumEntries), nil
+	}
+}
+
+func GetExtendedTcp6Table() ([]MibTcp6RowOwnerPid, error) {
+	var size uint32
+	err := getExtendedTcpTable(nil, &size, false, windows.AF_INET6, TcpTableOwnerPidConnections, 0)
+	if !errors.Is(err, windows.ERROR_INSUFFICIENT_BUFFER) {
+		return nil, os.NewSyscallError("GetExtendedTcpTable", err)
+	}
+	for {
+		table := make([]byte, size)
+		err = getExtendedTcpTable(&table[0], &size, false, windows.AF_INET6, TcpTableOwnerPidConnections, 0)
+		if err != nil {
+			if errors.Is(err, windows.ERROR_INSUFFICIENT_BUFFER) {
+				continue
+			}
+			return nil, os.NewSyscallError("GetExtendedTcpTable", err)
+		}
+		dwNumEntries := int(*(*uint32)(unsafe.Pointer(&table[0])))
+		return unsafe.Slice((*MibTcp6RowOwnerPid)(unsafe.Pointer(&table[offsetOfMibTcp6TableOwnerPid])), dwNumEntries), nil
+	}
+}
+
+func GetExtendedUdpTable() ([]MibUdpRowOwnerPid, error) {
+	var size uint32
+	err := getExtendedUdpTable(nil, &size, false, windows.AF_INET, UdpTableOwnerPid, 0)
+	if !errors.Is(err, windows.ERROR_INSUFFICIENT_BUFFER) {
+		return nil, os.NewSyscallError("GetExtendedUdpTable", err)
+	}
+	for {
+		table := make([]byte, size)
+		err = getExtendedUdpTable(&table[0], &size, false, windows.AF_INET, UdpTableOwnerPid, 0)
+		if err != nil {
+			if errors.Is(err, windows.ERROR_INSUFFICIENT_BUFFER) {
+				continue
+			}
+			return nil, os.NewSyscallError("GetExtendedUdpTable", err)
+		}
+		dwNumEntries := int(*(*uint32)(unsafe.Pointer(&table[0])))
+		return unsafe.Slice((*MibUdpRowOwnerPid)(unsafe.Pointer(&table[offsetOfMibUdpTableOwnerPid])), dwNumEntries), nil
+	}
+}
+
+func GetExtendedUdp6Table() ([]MibUdp6RowOwnerPid, error) {
+	var size uint32
+	err := getExtendedUdpTable(nil, &size, false, windows.AF_INET6, UdpTableOwnerPid, 0)
+	if !errors.Is(err, windows.ERROR_INSUFFICIENT_BUFFER) {
+		return nil, os.NewSyscallError("GetExtendedUdpTable", err)
+	}
+	for {
+		table := make([]byte, size)
+		err = getExtendedUdpTable(&table[0], &size, false, windows.AF_INET6, UdpTableOwnerPid, 0)
+		if err != nil {
+			if errors.Is(err, windows.ERROR_INSUFFICIENT_BUFFER) {
+				continue
+			}
+			return nil, os.NewSyscallError("GetExtendedUdpTable", err)
+		}
+		dwNumEntries := int(*(*uint32)(unsafe.Pointer(&table[0])))
+		return unsafe.Slice((*MibUdp6RowOwnerPid)(unsafe.Pointer(&table[offsetOfMibUdp6TableOwnerPid])), dwNumEntries), nil
+	}
+}
+
+func GetPerTcpConnectionEStatsSendBuffer(row *MibTcpRow) (*TcpEstatsSendBufferRodV0, error) {
+	var rod TcpEstatsSendBufferRodV0
+	err := getPerTcpConnectionEStats(row,
+		TcpConnectionEstatsSendBuff,
+		0,
+		0,
+		0,
+		0,
+		0,
+		0,
+		uintptr(unsafe.Pointer(&rod)),
+		0,
+		uint64(sizeOfTcpEstatsSendBufferRodV0),
+	)
+	if err != nil {
+		return nil, err
+	}
+	return &rod, nil
+}
+
+func GetPerTcp6ConnectionEStatsSendBuffer(row *MibTcp6Row) (*TcpEstatsSendBufferRodV0, error) {
+	var rod TcpEstatsSendBufferRodV0
+	err := getPerTcp6ConnectionEStats(row,
+		TcpConnectionEstatsSendBuff,
+		0,
+		0,
+		0,
+		0,
+		0,
+		0,
+		uintptr(unsafe.Pointer(&rod)),
+		0,
+		uint64(sizeOfTcpEstatsSendBufferRodV0),
+	)
+	if err != nil {
+		return nil, err
+	}
+	return &rod, nil
+}
+
+func SetPerTcpConnectionEStatsSendBuffer(row *MibTcpRow, rw *TcpEstatsSendBuffRwV0) error {
+	return setPerTcpConnectionEStats(row, TcpConnectionEstatsSendBuff, uintptr(unsafe.Pointer(&rw)), 0, uint64(sizeOfTcpEstatsSendBuffRwV0), 0)
+}
+
+func SetPerTcp6ConnectionEStatsSendBuffer(row *MibTcp6Row, rw *TcpEstatsSendBuffRwV0) error {
+	return setPerTcp6ConnectionEStats(row, TcpConnectionEstatsSendBuff, uintptr(unsafe.Pointer(&rw)), 0, uint64(sizeOfTcpEstatsSendBuffRwV0), 0)
+}

common/winiphlpapi/iphlpapi_test.go

@@ -0,0 +1,90 @@
+//go:build windows
+
+package winiphlpapi_test
+
+import (
+	"context"
+	"net"
+	"syscall"
+	"testing"
+
+	M "github.com/sagernet/sing/common/metadata"
+	N "github.com/sagernet/sing/common/network"
+	"github.com/sagernet/sing/common/winiphlpapi"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestFindPidTcp4(t *testing.T) {
+	t.Parallel()
+	listener, err := net.Listen("tcp", "127.0.0.1:0")
+	require.NoError(t, err)
+	defer listener.Close()
+	go listener.Accept()
+	conn, err := net.Dial("tcp", listener.Addr().String())
+	require.NoError(t, err)
+	defer conn.Close()
+	pid, err := winiphlpapi.FindPid(N.NetworkTCP, M.AddrPortFromNet(conn.LocalAddr()))
+	require.NoError(t, err)
+	require.Equal(t, uint32(syscall.Getpid()), pid)
+}
+
+func TestFindPidTcp6(t *testing.T) {
+	t.Parallel()
+	listener, err := net.Listen("tcp", "[::1]:0")
+	require.NoError(t, err)
+	defer listener.Close()
+	go listener.Accept()
+	conn, err := net.Dial("tcp", listener.Addr().String())
+	require.NoError(t, err)
+	defer conn.Close()
+	pid, err := winiphlpapi.FindPid(N.NetworkTCP, M.AddrPortFromNet(conn.LocalAddr()))
+	require.NoError(t, err)
+	require.Equal(t, uint32(syscall.Getpid()), pid)
+}
+
+func TestFindPidUdp4(t *testing.T) {
+	t.Parallel()
+	conn, err := net.ListenPacket("udp", "127.0.0.1:0")
+	require.NoError(t, err)
+	defer conn.Close()
+	pid, err := winiphlpapi.FindPid(N.NetworkUDP, M.AddrPortFromNet(conn.LocalAddr()))
+	require.NoError(t, err)
+	require.Equal(t, uint32(syscall.Getpid()), pid)
+}
+
+func TestFindPidUdp6(t *testing.T) {
+	t.Parallel()
+	conn, err := net.ListenPacket("udp", "[::1]:0")
+	require.NoError(t, err)
+	defer conn.Close()
+	pid, err := winiphlpapi.FindPid(N.NetworkUDP, M.AddrPortFromNet(conn.LocalAddr()))
+	require.NoError(t, err)
+	require.Equal(t, uint32(syscall.Getpid()), pid)
+}
+
+func TestWaitAck4(t *testing.T) {
+	t.Parallel()
+	listener, err := net.Listen("tcp", "127.0.0.1:0")
+	require.NoError(t, err)
+	defer listener.Close()
+	go listener.Accept()
+	conn, err := net.Dial("tcp", listener.Addr().String())
+	require.NoError(t, err)
+	defer conn.Close()
+	err = winiphlpapi.WriteAndWaitAck(context.Background(), conn, []byte("hello"))
+	require.NoError(t, err)
+}
+
+func TestWaitAck6(t *testing.T) {
+	t.Parallel()
+	listener, err := net.Listen("tcp", "[::1]:0")
+	require.NoError(t, err)
+	defer listener.Close()
+	go listener.Accept()
+	conn, err := net.Dial("tcp", listener.Addr().String())
+	require.NoError(t, err)
+	defer conn.Close()
+	err = winiphlpapi.WriteAndWaitAck(context.Background(), conn, []byte("hello"))
+	require.NoError(t, err)
+}

common/winiphlpapi/syscall_windows.go

@@ -0,0 +1,27 @@
+package winiphlpapi
+
+//go:generate go run golang.org/x/sys/windows/mkwinsyscall -output zsyscall_windows.go syscall_windows.go
+
+// https://learn.microsoft.com/en-us/windows/win32/api/iphlpapi/nf-iphlpapi-gettcptable
+//sys getTcpTable(tcpTable *byte, sizePointer *uint32, order bool) (errcode error) = iphlpapi.GetTcpTable
+
+// https://learn.microsoft.com/en-us/windows/win32/api/iphlpapi/nf-iphlpapi-gettcp6table
+//sys getTcp6Table(tcpTable *byte, sizePointer *uint32, order bool) (errcode error) = iphlpapi.GetTcp6Table
+
+// https://learn.microsoft.com/en-us/windows/win32/api/iphlpapi/nf-iphlpapi-getpertcpconnectionestats
+//sys getPerTcpConnectionEStats(row *MibTcpRow, estatsType uint32, rw uintptr, rwVersion uint64, rwSize uint64, ros uintptr, rosVersion uint64, rosSize uint64, rod uintptr, rodVersion uint64, rodSize uint64) (errcode error) = iphlpapi.GetPerTcpConnectionEStats
+
+// https://learn.microsoft.com/en-us/windows/win32/api/iphlpapi/nf-iphlpapi-getpertcp6connectionestats
+//sys getPerTcp6ConnectionEStats(row *MibTcp6Row, estatsType uint32, rw uintptr, rwVersion uint64, rwSize uint64, ros uintptr, rosVersion uint64, rosSize uint64, rod uintptr, rodVersion uint64, rodSize uint64) (errcode error) = iphlpapi.GetPerTcp6ConnectionEStats
+
+// https://learn.microsoft.com/en-us/windows/win32/api/iphlpapi/nf-iphlpapi-setpertcpconnectionestats
+//sys setPerTcpConnectionEStats(row *MibTcpRow, estatsType uint32, rw uintptr, rwVersion uint64, rwSize uint64, offset uint64) (errcode error) = iphlpapi.SetPerTcpConnectionEStats
+
+// https://learn.microsoft.com/en-us/windows/win32/api/iphlpapi/nf-iphlpapi-setpertcp6connectionestats
+//sys setPerTcp6ConnectionEStats(row *MibTcp6Row, estatsType uint32, rw uintptr, rwVersion uint64, rwSize uint64, offset uint64) (errcode error) = iphlpapi.SetPerTcp6ConnectionEStats
+
+// https://learn.microsoft.com/en-us/windows/win32/api/iphlpapi/nf-iphlpapi-getextendedtcptable
+//sys getExtendedTcpTable(pTcpTable *byte, pdwSize *uint32, bOrder bool, ulAf uint64, tableClass uint32, reserved uint64) = (errcode error) = iphlpapi.GetExtendedTcpTable
+
+// https://learn.microsoft.com/en-us/windows/win32/api/iphlpapi/nf-iphlpapi-getextendedudptable
+//sys getExtendedUdpTable(pUdpTable *byte, pdwSize *uint32, bOrder bool, ulAf uint64, tableClass uint32, reserved uint64) = (errcode error) = iphlpapi.GetExtendedUdpTable

common/winiphlpapi/zsyscall_windows.go

@@ -0,0 +1,131 @@
+// Code generated by 'go generate'; DO NOT EDIT.
+
+package winiphlpapi
+
+import (
+	"syscall"
+	"unsafe"
+
+	"golang.org/x/sys/windows"
+)
+
+var _ unsafe.Pointer
+
+// Do the interface allocations only once for common
+// Errno values.
+const (
+	errnoERROR_IO_PENDING = 997
+)
+
+var (
+	errERROR_IO_PENDING error = syscall.Errno(errnoERROR_IO_PENDING)
+	errERROR_EINVAL     error = syscall.EINVAL
+)
+
+// errnoErr returns common boxed Errno values, to prevent
+// allocations at runtime.
+func errnoErr(e syscall.Errno) error {
+	switch e {
+	case 0:
+		return errERROR_EINVAL
+	case errnoERROR_IO_PENDING:
+		return errERROR_IO_PENDING
+	}
+	// TODO: add more here, after collecting data on the common
+	// error values see on Windows. (perhaps when running
+	// all.bat?)
+	return e
+}
+
+var (
+	modiphlpapi = windows.NewLazySystemDLL("iphlpapi.dll")
+
+	procGetExtendedTcpTable        = modiphlpapi.NewProc("GetExtendedTcpTable")
+	procGetExtendedUdpTable        = modiphlpapi.NewProc("GetExtendedUdpTable")
+	procGetPerTcp6ConnectionEStats = modiphlpapi.NewProc("GetPerTcp6ConnectionEStats")
+	procGetPerTcpConnectionEStats  = modiphlpapi.NewProc("GetPerTcpConnectionEStats")
+	procGetTcp6Table               = modiphlpapi.NewProc("GetTcp6Table")
+	procGetTcpTable                = modiphlpapi.NewProc("GetTcpTable")
+	procSetPerTcp6ConnectionEStats = modiphlpapi.NewProc("SetPerTcp6ConnectionEStats")
+	procSetPerTcpConnectionEStats  = modiphlpapi.NewProc("SetPerTcpConnectionEStats")
+)
+
+func getExtendedTcpTable(pTcpTable *byte, pdwSize *uint32, bOrder bool, ulAf uint64, tableClass uint32, reserved uint64) (errcode error) {
+	var _p0 uint32
+	if bOrder {
+		_p0 = 1
+	}
+	r0, _, _ := syscall.Syscall6(procGetExtendedTcpTable.Addr(), 6, uintptr(unsafe.Pointer(pTcpTable)), uintptr(unsafe.Pointer(pdwSize)), uintptr(_p0), uintptr(ulAf), uintptr(tableClass), uintptr(reserved))
+	if r0 != 0 {
+		errcode = syscall.Errno(r0)
+	}
+	return
+}
+
+func getExtendedUdpTable(pUdpTable *byte, pdwSize *uint32, bOrder bool, ulAf uint64, tableClass uint32, reserved uint64) (errcode error) {
+	var _p0 uint32
+	if bOrder {
+		_p0 = 1
+	}
+	r0, _, _ := syscall.Syscall6(procGetExtendedUdpTable.Addr(), 6, uintptr(unsafe.Pointer(pUdpTable)), uintptr(unsafe.Pointer(pdwSize)), uintptr(_p0), uintptr(ulAf), uintptr(tableClass), uintptr(reserved))
+	if r0 != 0 {
+		errcode = syscall.Errno(r0)
+	}
+	return
+}
+
+func getPerTcp6ConnectionEStats(row *MibTcp6Row, estatsType uint32, rw uintptr, rwVersion uint64, rwSize uint64, ros uintptr, rosVersion uint64, rosSize uint64, rod uintptr, rodVersion uint64, rodSize uint64) (errcode error) {
+	r0, _, _ := syscall.Syscall12(procGetPerTcp6ConnectionEStats.Addr(), 11, uintptr(unsafe.Pointer(row)), uintptr(estatsType), uintptr(rw), uintptr(rwVersion), uintptr(rwSize), uintptr(ros), uintptr(rosVersion), uintptr(rosSize), uintptr(rod), uintptr(rodVersion), uintptr(rodSize), 0)
+	if r0 != 0 {
+		errcode = syscall.Errno(r0)
+	}
+	return
+}
+
+func getPerTcpConnectionEStats(row *MibTcpRow, estatsType uint32, rw uintptr, rwVersion uint64, rwSize uint64, ros uintptr, rosVersion uint64, rosSize uint64, rod uintptr, rodVersion uint64, rodSize uint64) (errcode error) {
+	r0, _, _ := syscall.Syscall12(procGetPerTcpConnectionEStats.Addr(), 11, uintptr(unsafe.Pointer(row)), uintptr(estatsType), uintptr(rw), uintptr(rwVersion), uintptr(rwSize), uintptr(ros), uintptr(rosVersion), uintptr(rosSize), uintptr(rod), uintptr(rodVersion), uintptr(rodSize), 0)
+	if r0 != 0 {
+		errcode = syscall.Errno(r0)
+	}
+	return
+}
+
+func getTcp6Table(tcpTable *byte, sizePointer *uint32, order bool) (errcode error) {
+	var _p0 uint32
+	if order {
+		_p0 = 1
+	}
+	r0, _, _ := syscall.Syscall(procGetTcp6Table.Addr(), 3, uintptr(unsafe.Pointer(tcpTable)), uintptr(unsafe.Pointer(sizePointer)), uintptr(_p0))
+	if r0 != 0 {
+		errcode = syscall.Errno(r0)
+	}
+	return
+}
+
+func getTcpTable(tcpTable *byte, sizePointer *uint32, order bool) (errcode error) {
+	var _p0 uint32
+	if order {
+		_p0 = 1
+	}
+	r0, _, _ := syscall.Syscall(procGetTcpTable.Addr(), 3, uintptr(unsafe.Pointer(tcpTable)), uintptr(unsafe.Pointer(sizePointer)), uintptr(_p0))
+	if r0 != 0 {
+		errcode = syscall.Errno(r0)
+	}
+	return
+}
+
+func setPerTcp6ConnectionEStats(row *MibTcp6Row, estatsType uint32, rw uintptr, rwVersion uint64, rwSize uint64, offset uint64) (errcode error) {
+	r0, _, _ := syscall.Syscall6(procSetPerTcp6ConnectionEStats.Addr(), 6, uintptr(unsafe.Pointer(row)), uintptr(estatsType), uintptr(rw), uintptr(rwVersion), uintptr(rwSize), uintptr(offset))
+	if r0 != 0 {
+		errcode = syscall.Errno(r0)
+	}
+	return
+}
+
+func setPerTcpConnectionEStats(row *MibTcpRow, estatsType uint32, rw uintptr, rwVersion uint64, rwSize uint64, offset uint64) (errcode error) {
+	r0, _, _ := syscall.Syscall6(procSetPerTcpConnectionEStats.Addr(), 6, uintptr(unsafe.Pointer(row)), uintptr(estatsType), uintptr(rw), uintptr(rwVersion), uintptr(rwSize), uintptr(offset))
+	if r0 != 0 {
+		errcode = syscall.Errno(r0)
+	}
+	return
+}

contrab/freelru/cache.go

@@ -49,12 +49,14 @@ type Cache[K comparable, V comparable] interface {
 
 	GetWithLifetime(key K) (V, time.Time, bool)
 
+	GetWithLifetimeNoExpire(key K) (V, time.Time, bool)
+
 	// GetAndRefresh returns the value associated with the key, setting it as the most
 	// recently used item.
 	// The lifetime of the found cache item is refreshed, even if it was already expired.
 	GetAndRefresh(key K) (V, bool)
 
-	GetAndRefreshOrAdd(key K, constructor func() (V, bool)) (V, bool)
+	GetAndRefreshOrAdd(key K, constructor func() (V, bool)) (V, bool, bool)
 
 	// Peek looks up a key's value from the cache, without changing its recent-ness.
 	// If the found entry is already expired, the evict function is called.

contrab/freelru/lru.go

@@ -500,6 +500,24 @@ func (lru *LRU[K, V]) getWithLifetime(hash uint32, key K) (value V, lifetime tim
 	return
 }
 
+func (lru *LRU[K, V]) GetWithLifetimeNoExpire(key K) (value V, lifetime time.Time, ok bool) {
+	return lru.getWithLifetimeNoExpire(lru.hash(key), key)
+}
+
+func (lru *LRU[K, V]) getWithLifetimeNoExpire(hash uint32, key K) (value V, lifetime time.Time, ok bool) {
+	if pos, ok := lru.findKeyNoExpire(hash, key); ok {
+		if pos != lru.head {
+			lru.unlinkElement(pos)
+			lru.setHead(pos)
+		}
+		lru.metrics.Hits++
+		return lru.elements[pos].value, time.UnixMilli(lru.elements[pos].expire), ok
+	}
+
+	lru.metrics.Misses++
+	return
+}
+
 // GetAndRefresh returns the value associated with the key, setting it as the most
 // recently used item.
 // The lifetime of the found cache item is refreshed, even if it was already expired.
@@ -522,11 +540,15 @@ func (lru *LRU[K, V]) getAndRefresh(hash uint32, key K) (value V, ok bool) {
 	return
 }
 
-func (lru *LRU[K, V]) GetAndRefreshOrAdd(key K, constructor func() (V, bool)) (V, bool) {
-	return lru.getAndRefreshOrAdd(lru.hash(key), key, constructor)
+func (lru *LRU[K, V]) GetAndRefreshOrAdd(key K, constructor func() (V, bool)) (V, bool, bool) {
+	value, updated, ok := lru.getAndRefreshOrAdd(lru.hash(key), key, constructor)
+	if !updated && ok {
+		lru.PurgeExpired()
+	}
+	return value, updated, ok
 }
 
-func (lru *LRU[K, V]) getAndRefreshOrAdd(hash uint32, key K, constructor func() (V, bool)) (value V, ok bool) {
+func (lru *LRU[K, V]) getAndRefreshOrAdd(hash uint32, key K, constructor func() (V, bool)) (value V, updated bool, ok bool) {
 	if pos, ok := lru.findKeyNoExpire(hash, key); ok {
 		if pos != lru.head {
 			lru.unlinkElement(pos)
@@ -534,17 +556,15 @@ func (lru *LRU[K, V]) getAndRefreshOrAdd(hash uint32, key K, constructor func()
 		}
 		lru.metrics.Hits++
 		lru.elements[pos].expire = expire(lru.lifetime)
-		return lru.elements[pos].value, ok
+		return lru.elements[pos].value, true, true
 	}
-
 	lru.metrics.Misses++
 	value, ok = constructor()
 	if !ok {
 		return
 	}
 	lru.addWithLifetime(hash, key, value, lru.lifetime)
-	lru.PurgeExpired()
-	return value, false
+	return value, false, true
 }
 
 // Peek looks up a key's value from the cache, without changing its recent-ness.

contrab/freelru/shardedlru.go

@@ -187,6 +187,17 @@ func (lru *ShardedLRU[K, V]) GetWithLifetime(key K) (value V, lifetime time.Time
 	return
 }
 
+func (lru *ShardedLRU[K, V]) GetWithLifetimeNoExpire(key K) (value V, lifetime time.Time, ok bool) {
+	hash := lru.hash(key)
+	shard := (hash >> 16) & lru.mask
+
+	lru.mus[shard].RLock()
+	value, lifetime, ok = lru.lrus[shard].getWithLifetimeNoExpire(hash, key)
+	lru.mus[shard].RUnlock()
+
+	return
+}
+
 // GetAndRefresh returns the value associated with the key, setting it as the most
 // recently used item.
 // The lifetime of the found cache item is refreshed, even if it was already expired.
@@ -201,14 +212,17 @@ func (lru *ShardedLRU[K, V]) GetAndRefresh(key K) (value V, ok bool) {
 	return
 }
 
-func (lru *ShardedLRU[K, V]) GetAndRefreshOrAdd(key K, constructor func() (V, bool)) (value V, updated bool) {
+func (lru *ShardedLRU[K, V]) GetAndRefreshOrAdd(key K, constructor func() (V, bool)) (value V, updated bool, ok bool) {
 	hash := lru.hash(key)
 	shard := (hash >> 16) & lru.mask
 
 	lru.mus[shard].Lock()
-	value, updated = lru.lrus[shard].getAndRefreshOrAdd(hash, key, constructor)
+	value, updated, ok = lru.lrus[shard].getAndRefreshOrAdd(hash, key, constructor)
 	lru.mus[shard].Unlock()
 
+	if !updated && ok {
+		lru.PurgeExpired()
+	}
 	return
 }
 

contrab/freelru/syncedlru.go

@@ -108,6 +108,16 @@ func (lru *SyncedLRU[K, V]) GetWithLifetime(key K) (value V, lifetime time.Time,
 	return
 }
 
+func (lru *SyncedLRU[K, V]) GetWithLifetimeNoExpire(key K) (value V, lifetime time.Time, ok bool) {
+	hash := lru.lru.hash(key)
+
+	lru.mu.Lock()
+	value, lifetime, ok = lru.lru.getWithLifetimeNoExpire(hash, key)
+	lru.mu.Unlock()
+
+	return
+}
+
 // GetAndRefresh returns the value associated with the key, setting it as the most
 // recently used item.
 // The lifetime of the found cache item is refreshed, even if it was already expired.
@@ -121,11 +131,14 @@ func (lru *SyncedLRU[K, V]) GetAndRefresh(key K) (value V, ok bool) {
 	return
 }
 
-func (lru *SyncedLRU[K, V]) GetAndRefreshOrAdd(key K, constructor func() (V, bool)) (value V, updated bool) {
+func (lru *SyncedLRU[K, V]) GetAndRefreshOrAdd(key K, constructor func() (V, bool)) (value V, updated bool, ok bool) {
 	hash := lru.lru.hash(key)
 
 	lru.mu.Lock()
-	value, updated = lru.lru.getAndRefreshOrAdd(hash, key, constructor)
+	value, updated, ok = lru.lru.getAndRefreshOrAdd(hash, key, constructor)
+	if !updated && ok {
+		lru.lru.PurgeExpired()
+	}
 	lru.mu.Unlock()
 
 	return

protocol/socks/handshake.go

@@ -10,6 +10,7 @@ import (
 
 	"github.com/sagernet/sing/common"
 	"github.com/sagernet/sing/common/auth"
+	"github.com/sagernet/sing/common/buf"
 	"github.com/sagernet/sing/common/bufio"
 	E "github.com/sagernet/sing/common/exceptions"
 	M "github.com/sagernet/sing/common/metadata"
@@ -24,6 +25,10 @@ type HandlerEx interface {
 	N.UDPConnectionHandlerEx
 }
 
+type PacketListener interface {
+	ListenPacket(listenConfig net.ListenConfig, ctx context.Context, network string, address string) (net.PacketConn, error)
+}
+
 func ClientHandshake4(conn io.ReadWriter, command byte, destination M.Socksaddr, username string) (socks4.Response, error) {
 	err := socks4.WriteRequest(conn, socks4.Request{
 		Command:     command,
@@ -120,6 +125,8 @@ func HandleConnectionEx(
 	ctx context.Context, conn net.Conn, reader *std_bufio.Reader,
 	authenticator *auth.Authenticator,
 	handler HandlerEx,
+	packetListener PacketListener,
+	// resolver TorResolver,
 	source M.Socksaddr,
 	onClose N.CloseHandlerFunc,
 ) error {
@@ -147,6 +154,11 @@ func HandleConnectionEx(
 			}
 			handler.NewConnectionEx(auth.ContextWithUser(ctx, request.Username), NewLazyConn(conn, version), source, request.Destination, onClose)
 			return nil
+		/*case CommandTorResolve, CommandTorResolvePTR:
+		if resolver == nil {
+			return E.New("socks4: torsocks: commands not implemented")
+		}
+		return handleTorSocks4(ctx, conn, request, resolver)*/
 		default:
 			err = socks4.WriteResponse(conn, socks4.Response{
 				ReplyCode: socks4.ReplyCodeRejectedOrFailed,
@@ -213,13 +225,40 @@ func HandleConnectionEx(
 			handler.NewConnectionEx(ctx, NewLazyConn(conn, version), source, request.Destination, onClose)
 			return nil
 		case socks5.CommandUDPAssociate:
-			var udpConn *net.UDPConn
-			udpConn, err = net.ListenUDP(M.NetworkFromNetAddr("udp", M.AddrFromNet(conn.LocalAddr())), net.UDPAddrFromAddrPort(netip.AddrPortFrom(M.AddrFromNet(conn.LocalAddr()), 0)))
-			if err != nil {
-				return err
+			var (
+				listenConfig net.ListenConfig
+				udpConn      net.PacketConn
+			)
+			if packetListener != nil {
+				udpConn, err = packetListener.ListenPacket(listenConfig, ctx, M.NetworkFromNetAddr("udp", M.AddrFromNet(conn.LocalAddr())), M.SocksaddrFrom(M.AddrFromNet(conn.LocalAddr()), 0).String())
+			} else {
+				udpConn, err = listenConfig.ListenPacket(ctx, M.NetworkFromNetAddr("udp", M.AddrFromNet(conn.LocalAddr())), M.SocksaddrFrom(M.AddrFromNet(conn.LocalAddr()), 0).String())
 			}
-			handler.NewPacketConnectionEx(ctx, NewLazyAssociatePacketConn(bufio.NewServerPacketConn(udpConn), conn), source, M.Socksaddr{}, onClose)
+			if err != nil {
+				return E.Cause(err, "socks5: listen udp")
+			}
+			err = socks5.WriteResponse(conn, socks5.Response{
+				ReplyCode: socks5.ReplyCodeSuccess,
+				Bind:      M.SocksaddrFromNet(udpConn.LocalAddr()),
+			})
+			if err != nil {
+				return E.Cause(err, "socks5: write response")
+			}
+			var socksPacketConn N.PacketConn = NewAssociatePacketConn(bufio.NewServerPacketConn(udpConn), M.Socksaddr{}, conn)
+			firstPacket := buf.NewPacket()
+			var destination M.Socksaddr
+			destination, err = socksPacketConn.ReadPacket(firstPacket)
+			if err != nil {
+				return E.Cause(err, "socks5: read first packet")
+			}
+			socksPacketConn = bufio.NewCachedPacketConn(socksPacketConn, firstPacket, destination)
+			handler.NewPacketConnectionEx(ctx, socksPacketConn, source, destination, onClose)
 			return nil
+		/*case CommandTorResolve, CommandTorResolvePTR:
+		if resolver == nil {
+			return E.New("socks4: torsocks: commands not implemented")
+		}
+		return handleTorSocks5(ctx, conn, request, resolver)*/
 		default:
 			err = socks5.WriteResponse(conn, socks5.Response{
 				ReplyCode: socks5.ReplyCodeUnsupported,

protocol/socks/handshake_tor.go

@@ -0,0 +1,146 @@
+package socks
+
+import (
+	"context"
+	"net"
+	"net/netip"
+	"os"
+	"strings"
+
+	E "github.com/sagernet/sing/common/exceptions"
+	M "github.com/sagernet/sing/common/metadata"
+	"github.com/sagernet/sing/protocol/socks/socks4"
+	"github.com/sagernet/sing/protocol/socks/socks5"
+)
+
+const (
+	CommandTorResolve    byte = 0xF0
+	CommandTorResolvePTR byte = 0xF1
+)
+
+type TorResolver interface {
+	LookupIP(ctx context.Context, host string) (netip.Addr, error)
+	LookupPTR(ctx context.Context, addr netip.Addr) (string, error)
+}
+
+func handleTorSocks4(ctx context.Context, conn net.Conn, request socks4.Request, resolver TorResolver) error {
+	switch request.Command {
+	case CommandTorResolve:
+		if !request.Destination.IsFqdn() {
+			return E.New("socks4: torsocks: invalid destination")
+		}
+		ipAddr, err := resolver.LookupIP(ctx, request.Destination.Fqdn)
+		if err != nil {
+			err = socks4.WriteResponse(conn, socks4.Response{
+				ReplyCode: socks4.ReplyCodeRejectedOrFailed,
+			})
+			if err != nil {
+				return err
+			}
+			return E.Cause(err, "socks4: torsocks: lookup failed for domain: ", request.Destination.Fqdn)
+		}
+		err = socks4.WriteResponse(conn, socks4.Response{
+			ReplyCode:   socks4.ReplyCodeGranted,
+			Destination: M.SocksaddrFrom(ipAddr, 0),
+		})
+		if err != nil {
+			return E.Cause(err, "socks4: torsocks: write response")
+		}
+		return nil
+	case CommandTorResolvePTR:
+		var ipAddr netip.Addr
+		if request.Destination.IsIP() {
+			ipAddr = request.Destination.Addr
+		} else if strings.HasSuffix(request.Destination.Fqdn, ".in-addr.arpa") {
+			ipAddr, _ = netip.ParseAddr(request.Destination.Fqdn[:len(request.Destination.Fqdn)-len(".in-addr.arpa")])
+		} else if strings.HasSuffix(request.Destination.Fqdn, ".ip6.arpa") {
+			ipAddr, _ = netip.ParseAddr(strings.ReplaceAll(request.Destination.Fqdn[:len(request.Destination.Fqdn)-len(".ip6.arpa")], ".", ":"))
+		}
+		if !ipAddr.IsValid() {
+			return E.New("socks4: torsocks: invalid destination")
+		}
+		host, err := resolver.LookupPTR(ctx, ipAddr)
+		if err != nil {
+			err = socks4.WriteResponse(conn, socks4.Response{
+				ReplyCode: socks4.ReplyCodeRejectedOrFailed,
+			})
+			if err != nil {
+				return err
+			}
+			return E.Cause(err, "socks4: torsocks: lookup PTR failed for ip: ", ipAddr)
+		}
+		err = socks4.WriteResponse(conn, socks4.Response{
+			ReplyCode: socks4.ReplyCodeGranted,
+			Destination: M.Socksaddr{
+				Fqdn: host,
+			},
+		})
+		if err != nil {
+			return E.Cause(err, "socks4: torsocks: write response")
+		}
+		return nil
+	default:
+		return os.ErrInvalid
+	}
+}
+
+func handleTorSocks5(ctx context.Context, conn net.Conn, request socks5.Request, resolver TorResolver) error {
+	switch request.Command {
+	case CommandTorResolve:
+		if !request.Destination.IsFqdn() {
+			return E.New("socks5: torsocks: invalid destination")
+		}
+		ipAddr, err := resolver.LookupIP(ctx, request.Destination.Fqdn)
+		if err != nil {
+			err = socks5.WriteResponse(conn, socks5.Response{
+				ReplyCode: socks5.ReplyCodeFailure,
+			})
+			if err != nil {
+				return err
+			}
+			return E.Cause(err, "socks5: torsocks: lookup failed for domain: ", request.Destination.Fqdn)
+		}
+		err = socks5.WriteResponse(conn, socks5.Response{
+			ReplyCode: socks5.ReplyCodeSuccess,
+			Bind:      M.SocksaddrFrom(ipAddr, 0),
+		})
+		if err != nil {
+			return E.Cause(err, "socks5: torsocks: write response")
+		}
+		return nil
+	case CommandTorResolvePTR:
+		var ipAddr netip.Addr
+		if request.Destination.IsIP() {
+			ipAddr = request.Destination.Addr
+		} else if strings.HasSuffix(request.Destination.Fqdn, ".in-addr.arpa") {
+			ipAddr, _ = netip.ParseAddr(request.Destination.Fqdn[:len(request.Destination.Fqdn)-len(".in-addr.arpa")])
+		} else if strings.HasSuffix(request.Destination.Fqdn, ".ip6.arpa") {
+			ipAddr, _ = netip.ParseAddr(strings.ReplaceAll(request.Destination.Fqdn[:len(request.Destination.Fqdn)-len(".ip6.arpa")], ".", ":"))
+		}
+		if !ipAddr.IsValid() {
+			return E.New("socks5: torsocks: invalid destination")
+		}
+		host, err := resolver.LookupPTR(ctx, ipAddr)
+		if err != nil {
+			err = socks5.WriteResponse(conn, socks5.Response{
+				ReplyCode: socks5.ReplyCodeFailure,
+			})
+			if err != nil {
+				return err
+			}
+			return E.Cause(err, "socks5: torsocks: lookup PTR failed for ip: ", ipAddr)
+		}
+		err = socks5.WriteResponse(conn, socks5.Response{
+			ReplyCode: socks5.ReplyCodeSuccess,
+			Bind: M.Socksaddr{
+				Fqdn: host,
+			},
+		})
+		if err != nil {
+			return E.Cause(err, "socks5: torsocks: write response")
+		}
+		return nil
+	default:
+		return os.ErrInvalid
+	}
+}