Add shadowtls v2 support

transport/shadowtls/client.go

@@ -0,0 +1,40 @@
+package shadowtls
+
+import (
+	"github.com/sagernet/sing/common/buf"
+	"github.com/sagernet/sing/common/bufio"
+	N "github.com/sagernet/sing/common/network"
+)
+
+var _ N.VectorisedWriter = (*ClientConn)(nil)
+
+type ClientConn struct {
+	*Conn
+	hashConn *HashReadConn
+}
+
+func NewClientConn(hashConn *HashReadConn) *ClientConn {
+	return &ClientConn{NewConn(hashConn.Conn), hashConn}
+}
+
+func (c *ClientConn) Write(p []byte) (n int, err error) {
+	if c.hashConn != nil {
+		sum := c.hashConn.Sum()
+		c.hashConn = nil
+		_, err = bufio.WriteVectorised(c.Conn, [][]byte{sum, p})
+		if err == nil {
+			n = len(p)
+		}
+		return
+	}
+	return c.Conn.Write(p)
+}
+
+func (c *ClientConn) WriteVectorised(buffers []*buf.Buffer) error {
+	if c.hashConn != nil {
+		sum := c.hashConn.Sum()
+		c.hashConn = nil
+		return c.Conn.WriteVectorised(append([]*buf.Buffer{buf.As(sum)}, buffers...))
+	}
+	return c.Conn.WriteVectorised(buffers)
+}