remove decryptor shutdown

we only needed it because of the nonce channels

router/connection.go

@@ -442,7 +442,6 @@ func (conn *LocalConnection) sendProtocolMsg(m ProtocolMsg) error {
 }
 
 func (conn *LocalConnection) receiveTCP(decoder *gob.Decoder) {
-	defer conn.Decryptor.Shutdown()
 	usingPassword := conn.SessionKey != nil
 	var receiver TCPReceiver
 	if usingPassword {

router/crypto.go

@@ -152,7 +152,6 @@ type FrameConsumer func(src []byte, dst []byte, frame []byte)
 
 type Decryptor interface {
 	IterateFrames([]byte, FrameConsumer) error
-	Shutdown()
 }
 
 type NonDecryptor struct {
@@ -209,9 +208,6 @@ func (nd *NonDecryptor) IterateFrames(packet []byte, consumer FrameConsumer) err
 	return nil
 }
 
-func (nd *NonDecryptor) Shutdown() {
-}
-
 func NewNaClDecryptor(sessionKey *[32]byte, outbound bool) *NaClDecryptor {
 	return &NaClDecryptor{
 		NonDecryptor: *NewNonDecryptor(),
@@ -220,9 +216,6 @@ func NewNaClDecryptor(sessionKey *[32]byte, outbound bool) *NaClDecryptor {
 		instanceDF:   NewNaClDecryptorInstance(outbound)}
 }
 
-func (nd *NaClDecryptor) Shutdown() {
-}
-
 func (nd *NaClDecryptor) IterateFrames(packet []byte, consumer FrameConsumer) error {
 	if len(packet) < 8 {
 		return PacketDecodingError{Desc: fmt.Sprintf("encrypted UDP packet too short; expected length >= 8, got %d", len(packet))}