Add hysteria2 protocol

transport/hysteria2/salamander.go

@@ -0,0 +1,106 @@
+package hysteria2
+
+import (
+	"net"
+
+	"github.com/sagernet/sing/common"
+	"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"
+	N "github.com/sagernet/sing/common/network"
+
+	"golang.org/x/crypto/blake2b"
+)
+
+const salamanderSaltLen = 8
+
+const ObfsTypeSalamander = "salamander"
+
+type Salamander struct {
+	net.PacketConn
+	password []byte
+}
+
+func NewSalamanderConn(conn net.PacketConn, password []byte) net.PacketConn {
+	writer, isVectorised := bufio.CreateVectorisedPacketWriter(conn)
+	if isVectorised {
+		return &VectorisedSalamander{
+			Salamander: Salamander{
+				PacketConn: conn,
+				password:   password,
+			},
+			writer: writer,
+		}
+	} else {
+		return &Salamander{
+			PacketConn: conn,
+			password:   password,
+		}
+	}
+}
+
+func (s *Salamander) ReadFrom(p []byte) (n int, addr net.Addr, err error) {
+	n, addr, err = s.PacketConn.ReadFrom(p)
+	if err != nil {
+		return
+	}
+	if n <= salamanderSaltLen {
+		return 0, nil, E.New("salamander: packet too short")
+	}
+	key := blake2b.Sum256(append(s.password, p[:salamanderSaltLen]...))
+	for index, c := range p[salamanderSaltLen:n] {
+		p[index] = c ^ key[index%blake2b.Size256]
+	}
+	return n - salamanderSaltLen, addr, nil
+}
+
+func (s *Salamander) WriteTo(p []byte, addr net.Addr) (n int, err error) {
+	buffer := buf.NewSize(len(p) + salamanderSaltLen)
+	defer buffer.Release()
+	buffer.WriteRandom(salamanderSaltLen)
+	key := blake2b.Sum256(append(s.password, buffer.Bytes()...))
+	for index, c := range p {
+		common.Must(buffer.WriteByte(c ^ key[index%blake2b.Size256]))
+	}
+	_, err = s.PacketConn.WriteTo(buffer.Bytes(), addr)
+	if err != nil {
+		return
+	}
+	return len(p), nil
+}
+
+type VectorisedSalamander struct {
+	Salamander
+	writer N.VectorisedPacketWriter
+}
+
+func (s *VectorisedSalamander) WriteTo(p []byte, addr net.Addr) (n int, err error) {
+	buffer := buf.NewSize(salamanderSaltLen)
+	buffer.WriteRandom(salamanderSaltLen)
+	key := blake2b.Sum256(append(s.password, buffer.Bytes()...))
+	for i := range p {
+		p[i] ^= key[i%blake2b.Size256]
+	}
+	err = s.writer.WriteVectorisedPacket([]*buf.Buffer{buffer, buf.As(p)}, M.SocksaddrFromNet(addr))
+	if err != nil {
+		return
+	}
+	return len(p), nil
+}
+
+func (s *VectorisedSalamander) WriteVectorisedPacket(buffers []*buf.Buffer, destination M.Socksaddr) error {
+	header := buf.NewSize(salamanderSaltLen)
+	defer header.Release()
+	header.WriteRandom(salamanderSaltLen)
+	key := blake2b.Sum256(append(s.password, header.Bytes()...))
+	var bufferIndex int
+	for _, buffer := range buffers {
+		content := buffer.Bytes()
+		for index, c := range content {
+			content[bufferIndex+index] = c ^ key[bufferIndex+index%blake2b.Size256]
+		}
+		bufferIndex += len(content)
+	}
+	return s.writer.WriteVectorisedPacket(append([]*buf.Buffer{header}, buffers...), destination)
+}