Add headroom interface

go.mod

@@ -3,7 +3,7 @@ module github.com/sagernet/sing-shadowsocks
 go 1.18
 
 require (
-	github.com/sagernet/sing v0.0.0-20220726034811-bc109486f14e
+	github.com/sagernet/sing v0.0.0-20220801112236-1bb95f9661fc
 	golang.org/x/crypto v0.0.0-20220622213112-05595931fe9d
 	lukechampine.com/blake3 v1.1.7
 )

go.sum

@@ -1,8 +1,8 @@
 github.com/klauspost/cpuid/v2 v2.0.9/go.mod h1:FInQzS24/EEf25PyTYn52gqo7WaD8xa0213Md/qVLRg=
 github.com/klauspost/cpuid/v2 v2.0.12 h1:p9dKCg8i4gmOxtv35DvrYoWqYzQrvEVdjQ762Y0OqZE=
 github.com/klauspost/cpuid/v2 v2.0.12/go.mod h1:g2LTdtYhdyuGPqyWyv7qRAmj1WBqxuObKfj5c0PQa7c=
-github.com/sagernet/sing v0.0.0-20220726034811-bc109486f14e h1:5lfrAc+vSv0iW6eHGNLyHC+a/k6BDGJvYxYxwB/68Kk=
-github.com/sagernet/sing v0.0.0-20220726034811-bc109486f14e/go.mod h1:GbtQfZSpmtD3cXeD1qX2LCMwY8dH+bnnInDTqd92IsM=
+github.com/sagernet/sing v0.0.0-20220801112236-1bb95f9661fc h1:x7H64IiqyrpxPWl/KrWkknzEK4GmpqgfZeVKFVw6E/M=
+github.com/sagernet/sing v0.0.0-20220801112236-1bb95f9661fc/go.mod h1:GbtQfZSpmtD3cXeD1qX2LCMwY8dH+bnnInDTqd92IsM=
 golang.org/x/crypto v0.0.0-20220622213112-05595931fe9d h1:sK3txAijHtOK88l68nt020reeT1ZdKLIYetKl95FzVY=
 golang.org/x/crypto v0.0.0-20220622213112-05595931fe9d/go.mod h1:IxCIyHEi3zRg3s0A5j5BB6A9Jmi73HwBIUl50j+osU4=
 golang.org/x/sys v0.0.0-20220715151400-c0bba94af5f8 h1:0A+M6Uqn+Eje4kHMK80dtF3JCXC4ykBgQG4Fe06QRhQ=

none.go

@@ -89,6 +89,13 @@ func (c *noneConn) WriteBuffer(buffer *buf.Buffer) error {
 	return common.Error(c.Conn.Write(buffer.Bytes()))
 }
 
+func (c *noneConn) Headroom() int {
+	if !c.handshake {
+		return M.SocksaddrSerializer.AddrPortLen(c.destination)
+	}
+	return 0
+}
+
 func (c *noneConn) ReadFrom(r io.Reader) (n int64, err error) {
 	if !c.handshake {
 		return bufio.ReadFrom0(c, r)
@@ -170,6 +177,10 @@ func (c *nonePacketConn) WriteTo(p []byte, addr net.Addr) (n int, err error) {
 	return len(p), nil
 }
 
+func (c *nonePacketConn) Headroom() int {
+	return M.MaxSocksaddrLength
+}
+
 type NoneService struct {
 	handler Handler
 	udpNat  *udpnat.Service[netip.AddrPort]
@@ -228,6 +239,10 @@ func (w *nonePacketWriter) Upstream() any {
 	return w.source
 }
 
+func (c *nonePacketWriter) Headroom() int {
+	return M.MaxSocksaddrLength
+}
+
 func (s *NoneService) NewError(ctx context.Context, err error) {
 	s.handler.NewError(ctx, err)
 }

shadowaead/protocol.go

@@ -310,6 +310,10 @@ func (c *clientPacketConn) WriteTo(p []byte, addr net.Addr) (n int, err error) {
 	return len(p), nil
 }
 
+func (c *clientPacketConn) Headroom() int {
+	return c.keySaltLength + M.MaxSocksaddrLength
+}
+
 func (c *clientPacketConn) Upstream() any {
 	return c.Conn
 }

shadowaead/service.go

@@ -280,6 +280,10 @@ func (w *serverPacketWriter) WritePacket(buffer *buf.Buffer, destination M.Socks
 	return w.source.WritePacket(buffer, M.SocksaddrFromNet(w.nat.LocalAddr()))
 }
 
+func (w *serverPacketWriter) Headroom() int {
+	return w.keySaltLength + M.MaxSocksaddrLength
+}
+
 func (w *serverPacketWriter) Upstream() any {
 	return w.source
 }

shadowaead_2022/protocol.go

@@ -802,6 +802,26 @@ func (c *clientPacketConn) WriteTo(p []byte, addr net.Addr) (n int, err error) {
 	return len(p), nil
 }
 
+func (c *clientPacketConn) Headroom() int {
+	var overHead int
+	if c.udpCipher != nil {
+		overHead = PacketNonceSize + shadowaead.Overhead
+	} else {
+		overHead = shadowaead.Overhead
+	}
+	overHead += 16 // packet header
+	pskLen := len(c.pskList)
+	if c.udpCipher == nil && pskLen > 1 {
+		overHead += (pskLen - 1) * aes.BlockSize
+	}
+	overHead += 1 // header type
+	overHead += 8 // timestamp
+	overHead += 2 // padding length
+	overHead += MaxPaddingLength
+	overHead += M.MaxSocksaddrLength
+	return overHead
+}
+
 type udpSession struct {
 	sessionId           uint64
 	packetId            uint64

shadowaead_2022/service.go

@@ -550,6 +550,21 @@ func (w *serverPacketWriter) WritePacket(buffer *buf.Buffer, destination M.Socks
 	return w.source.WritePacket(buffer, M.SocksaddrFromNet(w.nat.LocalAddr()))
 }
 
+func (w *serverPacketWriter) Headroom() int {
+	var hdrLen int
+	if w.udpCipher != nil {
+		hdrLen = PacketNonceSize
+	}
+	hdrLen += 16 // packet header
+	hdrLen += 1  // header type
+	hdrLen += 8  // timestamp
+	hdrLen += 8  // remote session id
+	hdrLen += 2  // padding length
+	hdrLen += MaxPaddingLength
+	hdrLen += M.MaxSocksaddrLength
+	return hdrLen
+}
+
 func (w *serverPacketWriter) Upstream() any {
 	return w.source
 }

shadowstream/protocol.go

@@ -325,6 +325,10 @@ func (c *clientPacketConn) WriteTo(p []byte, addr net.Addr) (n int, err error) {
 	return len(p), nil
 }
 
+func (c *clientPacketConn) Headroom() int {
+	return c.saltLength + M.MaxSocksaddrLength
+}
+
 func (c *clientPacketConn) Upstream() any {
 	return c.Conn
 }