refactor: make 'inner' encoder/decoder explicit

router/crypto.go

@@ -337,9 +337,9 @@ type SimpleTCPSender struct {
 }
 
 type EncryptedTCPSender struct {
-	SimpleTCPSender
 	sync.RWMutex
-	state *TCPCryptoState
+	sender TCPSender
+	state  *TCPCryptoState
 }
 
 func NewSimpleTCPSender(encoder *gob.Encoder) *SimpleTCPSender {
@@ -350,10 +350,8 @@ func (sender *SimpleTCPSender) Send(msg []byte) error {
 	return sender.encoder.Encode(msg)
 }
 
-func NewEncryptedTCPSender(encoder *gob.Encoder, sessionKey *[32]byte, outbound bool) *EncryptedTCPSender {
-	return &EncryptedTCPSender{
-		SimpleTCPSender: *NewSimpleTCPSender(encoder),
-		state:           NewTCPCryptoState(sessionKey, outbound)}
+func NewEncryptedTCPSender(sender TCPSender, sessionKey *[32]byte, outbound bool) *EncryptedTCPSender {
+	return &EncryptedTCPSender{sender: sender, state: NewTCPCryptoState(sessionKey, outbound)}
 }
 
 func (sender *EncryptedTCPSender) Send(msg []byte) error {
@@ -361,7 +359,7 @@ func (sender *EncryptedTCPSender) Send(msg []byte) error {
 	defer sender.Unlock()
 	encodedMsg := secretbox.Seal(nil, msg, &sender.state.nonce, sender.state.sessionKey)
 	sender.state.advance()
-	return sender.SimpleTCPSender.Send(encodedMsg)
+	return sender.sender.Send(encodedMsg)
 }
 
 type TCPReceiver interface {
@@ -373,8 +371,8 @@ type SimpleTCPReceiver struct {
 }
 
 type EncryptedTCPReceiver struct {
-	SimpleTCPReceiver
-	state *TCPCryptoState
+	receiver TCPReceiver
+	state    *TCPCryptoState
 }
 
 func NewSimpleTCPReceiver(decoder *gob.Decoder) *SimpleTCPReceiver {
@@ -387,14 +385,12 @@ func (receiver *SimpleTCPReceiver) Receive() ([]byte, error) {
 	return msg, err
 }
 
-func NewEncryptedTCPReceiver(decoder *gob.Decoder, sessionKey *[32]byte, outbound bool) *EncryptedTCPReceiver {
-	return &EncryptedTCPReceiver{
-		SimpleTCPReceiver: *NewSimpleTCPReceiver(decoder),
-		state:             NewTCPCryptoState(sessionKey, !outbound)}
+func NewEncryptedTCPReceiver(receiver TCPReceiver, sessionKey *[32]byte, outbound bool) *EncryptedTCPReceiver {
+	return &EncryptedTCPReceiver{receiver: receiver, state: NewTCPCryptoState(sessionKey, !outbound)}
 }
 
 func (receiver *EncryptedTCPReceiver) Receive() ([]byte, error) {
-	msg, err := receiver.SimpleTCPReceiver.Receive()
+	msg, err := receiver.receiver.Receive()
 	if err != nil {
 		return nil, err
 	}

router/protocol.go

@@ -180,12 +180,13 @@ func (res *ProtocolIntroResults) doIntroV1(params ProtocolIntroParams, pubKey, p
 		return err
 	}
 
+	res.Sender = NewSimpleTCPSender(enc)
+	res.Receiver = NewSimpleTCPReceiver(dec)
+
 	if pubKey == nil {
 		if _, present := res.Features["PublicKey"]; present {
 			return ErrExpectedNoCrypto
 		}
-
-		res.setupNoCrypto(enc, dec)
 	} else {
 		remotePubKeyStr, ok := res.Features["PublicKey"]
 		if !ok {
@@ -197,7 +198,7 @@ func (res *ProtocolIntroResults) doIntroV1(params ProtocolIntroParams, pubKey, p
 			return err
 		}
 
-		res.setupCrypto(params, enc, dec, remotePubKey, privKey)
+		res.setupCrypto(params, remotePubKey, privKey)
 	}
 
 	res.Features = filterV1Features(res.Features)
@@ -265,7 +266,8 @@ func (res *ProtocolIntroResults) doIntroV2(params ProtocolIntroParams, pubKey, p
 			return ErrExpectedCrypto
 		}
 
-		res.setupNoCrypto(gob.NewEncoder(params.Conn), gob.NewDecoder(params.Conn))
+		res.Sender = NewSimpleTCPSender(gob.NewEncoder(params.Conn))
+		res.Receiver = NewSimpleTCPReceiver(gob.NewDecoder(params.Conn))
 
 	case 1:
 		if pubKey == nil {
@@ -277,7 +279,9 @@ func (res *ProtocolIntroResults) doIntroV2(params ProtocolIntroParams, pubKey, p
 			return err
 		}
 
-		res.setupCrypto(params, gob.NewEncoder(params.Conn), gob.NewDecoder(params.Conn), rbuf, privKey)
+		res.Sender = NewSimpleTCPSender(gob.NewEncoder(params.Conn))
+		res.Receiver = NewSimpleTCPReceiver(gob.NewDecoder(params.Conn))
+		res.setupCrypto(params, rbuf, privKey)
 
 	default:
 		return fmt.Errorf("Bad encryption flag %d", rbuf[0])
@@ -314,18 +318,12 @@ func (res *ProtocolIntroResults) doIntroV2(params ProtocolIntroParams, pubKey, p
 	return nil
 }
 
-func (res *ProtocolIntroResults) setupNoCrypto(enc *gob.Encoder, dec *gob.Decoder) {
-	res.Sender = NewSimpleTCPSender(enc)
-	res.Receiver = NewSimpleTCPReceiver(dec)
-}
-
-func (res *ProtocolIntroResults) setupCrypto(params ProtocolIntroParams,
-	enc *gob.Encoder, dec *gob.Decoder, remotePubKey []byte, privKey *[32]byte) {
+func (res *ProtocolIntroResults) setupCrypto(params ProtocolIntroParams, remotePubKey []byte, privKey *[32]byte) {
 	var remotePubKeyArr [32]byte
 	copy(remotePubKeyArr[:], remotePubKey)
 	res.SessionKey = FormSessionKey(&remotePubKeyArr, privKey, params.Password)
-	res.Sender = NewEncryptedTCPSender(enc, res.SessionKey, params.Outbound)
-	res.Receiver = NewEncryptedTCPReceiver(dec, res.SessionKey, params.Outbound)
+	res.Sender = NewEncryptedTCPSender(res.Sender, res.SessionKey, params.Outbound)
+	res.Receiver = NewEncryptedTCPReceiver(res.Receiver, res.SessionKey, params.Outbound)
 }
 
 type ProtocolTag byte