Add shadowtls v2 support

transport/shadowtls/hash.go

@@ -0,0 +1,60 @@
+package shadowtls
+
+import (
+	"crypto/hmac"
+	"crypto/sha1"
+	"hash"
+	"net"
+)
+
+type HashReadConn struct {
+	net.Conn
+	hmac hash.Hash
+}
+
+func NewHashReadConn(conn net.Conn, password string) *HashReadConn {
+	return &HashReadConn{
+		conn,
+		hmac.New(sha1.New, []byte(password)),
+	}
+}
+
+func (c *HashReadConn) Read(b []byte) (n int, err error) {
+	n, err = c.Conn.Read(b)
+	if err != nil {
+		return
+	}
+	_, err = c.hmac.Write(b[:n])
+	return
+}
+
+func (c *HashReadConn) Sum() []byte {
+	return c.hmac.Sum(nil)[:8]
+}
+
+type HashWriteConn struct {
+	net.Conn
+	hmac hash.Hash
+}
+
+func NewHashWriteConn(conn net.Conn, password string) *HashWriteConn {
+	return &HashWriteConn{
+		conn,
+		hmac.New(sha1.New, []byte(password)),
+	}
+}
+
+func (c *HashWriteConn) Write(p []byte) (n int, err error) {
+	if c.hmac != nil {
+		c.hmac.Write(p)
+	}
+	return c.Conn.Write(p)
+}
+
+func (c *HashWriteConn) Sum() []byte {
+	return c.hmac.Sum(nil)[:8]
+}
+
+func (c *HashWriteConn) Fallback() {
+	c.hmac = nil
+}