Export std net bind

conn/bind_std.go

@@ -16,6 +16,9 @@ import (
 	"sync"
 	"syscall"
 
+	"github.com/sagernet/sing/common"
+	"github.com/sagernet/sing/common/control"
+	M "github.com/sagernet/sing/common/metadata"
 	"golang.org/x/net/ipv4"
 	"golang.org/x/net/ipv6"
 )
@@ -28,6 +31,9 @@ var _ Bind = (*StdNetBind)(nil)
 // methods for sending and receiving multiple datagrams per-syscall. See the
 // proposal in https://github.com/golang/go/issues/45886#issuecomment-1218301564.
 type StdNetBind struct {
+	externalControl     control.Func
+	reservedForEndpoint map[netip.AddrPort][3]uint8
+
 	mu            sync.Mutex // protects all fields except as specified
 	ipv4          *net.UDPConn
 	ipv6          *net.UDPConn
@@ -46,8 +52,11 @@ type StdNetBind struct {
 	blackhole6 bool
 }
 
-func NewStdNetBind() Bind {
+func NewStdNetBind(externalControl control.Func) Bind {
 	return &StdNetBind{
+		externalControl:     externalControl,
+		reservedForEndpoint: make(map[netip.AddrPort][3]uint8),
+
 		udpAddrPool: sync.Pool{
 			New: func() any {
 				return &net.UDPAddr{
@@ -117,8 +126,29 @@ func (e *StdNetEndpoint) DstToString() string {
 	return e.AddrPort.String()
 }
 
-func listenNet(network string, port int) (*net.UDPConn, int, error) {
+func listenNet(externalControl control.Func, network string, port int) (*net.UDPConn, int, error) {
-	conn, err := listenConfig().ListenPacket(context.Background(), network, ":"+strconv.Itoa(port))
+	var listenerAddr string
+	if network == "udp6" {
+		listenerAddr = "[::]:" + strconv.Itoa(port)
+	} else {
+		listenerAddr = ":" + strconv.Itoa(port)
+	}
+
+	var listener net.ListenConfig
+	listener.Control = func(network, address string, conn syscall.RawConn) error {
+		for _, wgControlFn := range controlFns {
+			err := wgControlFn(network, address, conn)
+			if err != nil {
+				return err
+			}
+		}
+		if externalControl != nil {
+			return externalControl(network, address, conn)
+		} else {
+			return nil
+		}
+	}
+	conn, err := listener.ListenPacket(context.Background(), network, listenerAddr)
 	if err != nil {
 		return nil, 0, err
 	}
@@ -154,13 +184,13 @@ again:
 	var v4pc *ipv4.PacketConn
 	var v6pc *ipv6.PacketConn
 
-	v4conn, port, err = listenNet("udp4", port)
+	v4conn, port, err = listenNet(s.externalControl, "udp4", port)
 	if err != nil && !errors.Is(err, syscall.EAFNOSUPPORT) {
 		return nil, 0, err
 	}
 
 	// Listen on the same port as we're using for ipv4.
-	v6conn, port, err = listenNet("udp6", port)
+	v6conn, port, err = listenNet(s.externalControl, "udp6", port)
 	if uport == 0 && errors.Is(err, syscall.EADDRINUSE) && tries < 100 {
 		v4conn.Close()
 		tries++
@@ -265,8 +295,10 @@ func (s *StdNetBind) receiveIP(
 		if sizes[i] == 0 {
 			continue
 		}
-		addrPort := msg.Addr.(*net.UDPAddr).AddrPort()
+		if msg.N > 3 {
-		ep := &StdNetEndpoint{AddrPort: addrPort} // TODO: remove allocation
+			common.ClearArray(bufs[i][1:4])
+		}
+		ep := &StdNetEndpoint{AddrPort: M.AddrPortFromNet(msg.Addr)} // TODO: remove allocation
 		getSrcFromControl(msg.OOB[:msg.NN], ep)
 		eps[i] = ep
 	}
@@ -375,6 +407,14 @@ func (s *StdNetBind) Send(bufs [][]byte, endpoint Endpoint, offset int) error {
 		retried bool
 		err     error
 	)
+	for _, buf := range bufs {
+		if len(buf) > 3 {
+			reserved, loaded := s.reservedForEndpoint[endpoint.(*StdNetEndpoint).AddrPort]
+			if loaded {
+				copy(buf[1:4], reserved[:])
+			}
+		}
+	}
 retry:
 	if offload {
 		n := coalesceMessages(ua, endpoint.(*StdNetEndpoint), bufs, offset, *msgs, setGSOSize)
@@ -405,6 +445,10 @@ retry:
 	return err
 }
 
+func (s *StdNetBind) SetReservedForEndpoint(destination netip.AddrPort, reserved [3]byte) {
+	s.reservedForEndpoint[destination] = reserved
+}
+
 func (s *StdNetBind) send(conn *net.UDPConn, pc batchWriter, msgs []ipv6.Message) error {
 	var (
 		n     int

conn/bind_windows.go

@@ -15,6 +15,10 @@ import (
 	"sync/atomic"
 	"unsafe"
 
+	"github.com/sagernet/sing/common"
+	"github.com/sagernet/sing/common/control"
+	E "github.com/sagernet/sing/common/exceptions"
+	M "github.com/sagernet/sing/common/metadata"
 	"github.com/sagernet/wireguard-go/conn/winrio"
 	"golang.org/x/sys/windows"
 )
@@ -71,18 +75,26 @@ type afWinRingBind struct {
 
 // WinRingBind uses Windows registered I/O for fast ring buffered networking.
 type WinRingBind struct {
+	externalControl     control.Func
+	reservedForEndpoint map[WinRingEndpoint][3]uint8
+
 	v4, v6 afWinRingBind
 	mu     sync.RWMutex
 	isOpen atomic.Uint32 // 0, 1, or 2
 }
 
-func NewDefaultBind() Bind { return NewWinRingBind() }
+func NewDefaultBind(externalControl control.Func) Bind {
+	return NewWinRingBind(externalControl)
+}
 
-func NewWinRingBind() Bind {
+func NewWinRingBind(externalControl control.Func) Bind {
 	if !winrio.Initialize() {
-		return NewStdNetBind()
+		return NewStdNetBind(externalControl)
+	}
+	return &WinRingBind{
+		externalControl:     externalControl,
+		reservedForEndpoint: make(map[WinRingEndpoint][3]uint8),
 	}
-	return new(WinRingBind)
 }
 
 type WinRingEndpoint struct {
@@ -238,7 +250,7 @@ func (ring *ringBuffer) Open() error {
 	return nil
 }
 
-func (bind *afWinRingBind) Open(family int32, sa windows.Sockaddr) (windows.Sockaddr, error) {
+func (bind *afWinRingBind) Open(family int32, sa windows.Sockaddr, externalControl control.Func) (windows.Sockaddr, error) {
 	var err error
 	bind.sock, err = winrio.Socket(family, windows.SOCK_DGRAM, windows.IPPROTO_UDP)
 	if err != nil {
@@ -256,6 +268,19 @@ func (bind *afWinRingBind) Open(family int32, sa windows.Sockaddr) (windows.Sock
 	if err != nil {
 		return nil, err
 	}
+	var network string
+	switch family {
+	case windows.AF_INET:
+		network = "udp4"
+	case windows.AF_INET6:
+		network = "udp6"
+	}
+	if externalControl != nil {
+		err = externalControl(network, M.AddrPortFromSockaddr(sa).String(), &fakeRawConn{bind.sock})
+		if err != nil {
+			return nil, err
+		}
+	}
 	err = windows.Bind(bind.sock, sa)
 	if err != nil {
 		return nil, err
@@ -267,6 +292,23 @@ func (bind *afWinRingBind) Open(family int32, sa windows.Sockaddr) (windows.Sock
 	return sa, nil
 }
 
+type fakeRawConn struct {
+	socket windows.Handle
+}
+
+func (c *fakeRawConn) Control(f func(fd uintptr)) error {
+	f(uintptr(c.socket))
+	return nil
+}
+
+func (c *fakeRawConn) Read(f func(fd uintptr) (done bool)) error {
+	panic("not implemented")
+}
+
+func (c *fakeRawConn) Write(f func(fd uintptr) (done bool)) error {
+	panic("not implemented")
+}
+
 func (bind *WinRingBind) Open(port uint16) (recvFns []ReceiveFunc, selectedPort uint16, err error) {
 	bind.mu.Lock()
 	defer bind.mu.Unlock()
@@ -279,11 +321,11 @@ func (bind *WinRingBind) Open(port uint16) (recvFns []ReceiveFunc, selectedPort
 		return nil, 0, ErrBindAlreadyOpen
 	}
 	var sa windows.Sockaddr
-	sa, err = bind.v4.Open(windows.AF_INET, &windows.SockaddrInet4{Port: int(port)})
+	sa, err = bind.v4.Open(windows.AF_INET, &windows.SockaddrInet4{Port: int(port)}, bind.externalControl)
 	if err != nil {
 		return nil, 0, err
 	}
-	sa, err = bind.v6.Open(windows.AF_INET6, &windows.SockaddrInet6{Port: sa.(*windows.SockaddrInet4).Port})
+	sa, err = bind.v6.Open(windows.AF_INET6, &windows.SockaddrInet6{Port: sa.(*windows.SockaddrInet4).Port}, bind.externalControl)
 	if err != nil {
 		return nil, 0, err
 	}
@@ -419,6 +461,9 @@ func (bind *WinRingBind) receiveIPv4(bufs [][]byte, sizes []int, eps []Endpoint)
 	bind.mu.RLock()
 	defer bind.mu.RUnlock()
 	n, ep, err := bind.v4.Receive(bufs[0], &bind.isOpen)
+	if n > 3 {
+		common.ClearArray(bufs[0][1:4])
+	}
 	sizes[0] = n
 	eps[0] = ep
 	return 1, err
@@ -428,6 +473,9 @@ func (bind *WinRingBind) receiveIPv6(bufs [][]byte, sizes []int, eps []Endpoint)
 	bind.mu.RLock()
 	defer bind.mu.RUnlock()
 	n, ep, err := bind.v6.Receive(bufs[0], &bind.isOpen)
+	if n > 3 {
+		common.ClearArray(bufs[0][1:4])
+	}
 	sizes[0] = n
 	eps[0] = ep
 	return 1, err
@@ -494,6 +542,12 @@ func (bind *WinRingBind) Send(bufs [][]byte, endpoint Endpoint, offset int) erro
 	defer bind.mu.RUnlock()
 	for _, buf := range bufs {
 		buf = buf[offset:]
+		if len(buf) > 3 {
+			reserved, loaded := bind.reservedForEndpoint[*endpoint.(*WinRingEndpoint)]
+			if loaded {
+				copy(buf[1:4], reserved[:])
+			}
+		}
 		switch nend.family {
 		case windows.AF_INET:
 			if bind.v4.blackhole {
@@ -514,6 +568,14 @@ func (bind *WinRingBind) Send(bufs [][]byte, endpoint Endpoint, offset int) erro
 	return nil
 }
 
+func (bind *WinRingBind) SetReservedForEndpoint(destination netip.AddrPort, reserved [3]byte) {
+	endpoint, err := bind.ParseEndpoint(destination.String())
+	if err != nil {
+		panic(E.Cause(err, "parse destination as WinRingEndpoint"))
+	}
+	bind.reservedForEndpoint[*endpoint.(*WinRingEndpoint)] = reserved
+}
+
 func (s *StdNetBind) BindSocketToInterface4(interfaceIndex uint32, blackhole bool) error {
 	s.mu.Lock()
 	defer s.mu.Unlock()

conn/conn.go

@@ -57,6 +57,8 @@ type Bind interface {
 	// BatchSize is the number of buffers expected to be passed to
 	// the ReceiveFuncs, and the maximum expected to be passed to SendBatch.
 	BatchSize() int
+
+	SetReservedForEndpoint(destination netip.AddrPort, reserved [3]byte)
 }
 
 // BindSocketToInterface is implemented by Bind objects that support being

conn/controlfns.go

@@ -6,8 +6,7 @@
 package conn
 
 import (
-	"net"
+	"github.com/sagernet/sing/common/control"
-	"syscall"
 )
 
 // UDP socket read/write buffer size (7MB). The value of 7MB is chosen as it is
@@ -17,27 +16,6 @@ import (
 // around this limitation)
 const socketBufferSize = 7 << 20
 
-// controlFn is the callback function signature from net.ListenConfig.Control.
-// It is used to apply platform specific configuration to the socket prior to
-// bind.
-type controlFn func(network, address string, c syscall.RawConn) error
-
 // controlFns is a list of functions that are called from the listen config
 // that can apply socket options.
-var controlFns = []controlFn{}
+var controlFns []control.Func
-
-// listenConfig returns a net.ListenConfig that applies the controlFns to the
-// socket prior to bind. This is used to apply socket buffer sizing and packet
-// information OOB configuration for sticky sockets.
-func listenConfig() *net.ListenConfig {
-	return &net.ListenConfig{
-		Control: func(network, address string, c syscall.RawConn) error {
-			for _, fn := range controlFns {
-				if err := fn(network, address, c); err != nil {
-					return err
-				}
-			}
-			return nil
-		},
-	}
-}

conn/default.go

@@ -7,4 +7,8 @@
 
 package conn
 
-func NewDefaultBind() Bind { return NewStdNetBind() }
+import "github.com/sagernet/sing/common/control"
+
+func NewDefaultBind(externalControl control.Func) Bind {
+	return NewStdNetBind(externalControl)
+}