Direct WebSocket

internal/client/auth.go

@@ -13,11 +13,11 @@ const (
 )
 
 type chHiddenData struct {
-	rawCiphertextWithTag []byte
-	chRandom             []byte
-	chSessionId          []byte
-	chX25519KeyShare     []byte
-	chExtSNI             []byte
+	fullRaw          []byte // pubkey, ciphertext, tag
+	chRandom         []byte
+	chSessionId      []byte
+	chX25519KeyShare []byte
+	chExtSNI         []byte
 }
 
 // makeHiddenData generates the ephemeral key pair, calculates the shared secret, and then compose and
@@ -50,7 +50,7 @@ func makeHiddenData(sta *State) (ret chHiddenData, sharedSecret []byte) {
 	sharedSecret = ecdh.GenerateSharedSecret(ephPv, sta.staticPub)
 	nonce := ret.chRandom[0:12]
 	ciphertextWithTag, _ := util.AESGCMEncrypt(nonce, sharedSecret, plaintext)
-	ret.rawCiphertextWithTag = ciphertextWithTag
+	ret.fullRaw = append(ret.chRandom, ciphertextWithTag...)
 	ret.chSessionId = ciphertextWithTag[0:32]
 	ret.chX25519KeyShare = ciphertextWithTag[32:64]
 	ret.chExtSNI = makeServerName(sta.ServerName)

internal/client/websocket.go

@@ -3,53 +3,14 @@ package client
 import (
 	"encoding/base64"
 	"errors"
+	"fmt"
 	"github.com/cbeuw/Cloak/internal/util"
+	"github.com/gorilla/websocket"
 	"net"
 	"net/http"
 	"net/url"
-	"time"
-
-	"github.com/gorilla/websocket"
 )
 
-type WebSocketConn struct {
-	c *websocket.Conn
-}
-
-func (ws *WebSocketConn) Write(data []byte) (int, error) {
-	err := ws.c.WriteMessage(websocket.BinaryMessage, data)
-	if err != nil {
-		return 0, err
-	} else {
-		return len(data), nil
-	}
-}
-
-func (ws *WebSocketConn) Read(buf []byte) (int, error) {
-	_, r, err := ws.c.NextReader()
-	if err != nil {
-		return 0, err
-	}
-	return r.Read(buf)
-}
-
-func (ws *WebSocketConn) Close() error         { return ws.c.Close() }
-func (ws *WebSocketConn) LocalAddr() net.Addr  { return ws.c.LocalAddr() }
-func (ws *WebSocketConn) RemoteAddr() net.Addr { return ws.c.RemoteAddr() }
-func (ws *WebSocketConn) SetDeadline(t time.Time) error {
-	err := ws.c.SetReadDeadline(t)
-	if err != nil {
-		return err
-	}
-	err = ws.c.SetWriteDeadline(t)
-	if err != nil {
-		return err
-	}
-	return nil
-}
-func (ws *WebSocketConn) SetReadDeadline(t time.Time) error  { return ws.c.SetReadDeadline(t) }
-func (ws *WebSocketConn) SetWriteDeadline(t time.Time) error { return ws.c.SetWriteDeadline(t) }
-
 type WebSocket struct {
 	Transport
 }
@@ -57,27 +18,31 @@ type WebSocket struct {
 func (WebSocket) PrepareConnection(sta *State, conn net.Conn) (sessionKey []byte, err error) {
 	u, err := url.Parse("ws://" + sta.RemoteHost + ":" + sta.RemotePort) //TODO IPv6
 	if err != nil {
-		return nil, err
+		return nil, fmt.Errorf("failed to parse ws url: %v")
 	}
 
 	hd, sharedSecret := makeHiddenData(sta)
 	header := http.Header{}
-	header.Add("hidden", base64.StdEncoding.EncodeToString(hd.rawCiphertextWithTag))
-	c, resp, err := websocket.NewClient(conn, u, header, 16480, 16480)
+	header.Add("hidden", base64.StdEncoding.EncodeToString(hd.fullRaw))
+	c, _, err := websocket.NewClient(conn, u, header, 16480, 16480)
 	if err != nil {
-		return nil, err
+		return nil, fmt.Errorf("failed to handshake: %v", err)
 	}
 
-	reply, err := base64.StdEncoding.DecodeString(resp.Header.Get("reply"))
+	conn = &util.WebSocketConn{c}
+
+	buf := make([]byte, 128)
+	n, err := conn.Read(buf)
 	if err != nil {
-		return nil, err
+		return nil, fmt.Errorf("failed to read reply: %v", err)
 	}
 
-	if len(reply) != 60 {
+	if n != 60 {
 		return nil, errors.New("reply must be 60 bytes")
 	}
+
+	reply := buf[:60]
 	sessionKey, err = util.AESGCMDecrypt(reply[:12], sharedSecret, reply[12:])
 
-	conn = &WebSocketConn{c: c}
 	return
 }

internal/server/TLS.go

@@ -10,9 +10,6 @@ import (
 	"fmt"
 	"github.com/cbeuw/Cloak/internal/ecdh"
 	"github.com/cbeuw/Cloak/internal/util"
-	"net"
-
-	log "github.com/sirupsen/logrus"
 )
 
 // ClientHello contains every field in a ClientHello message
@@ -247,51 +244,3 @@ func unmarshalClientHello(ch *ClientHello, staticPv crypto.PrivateKey) (ai authe
 	}
 	return
 }
-
-// PrepareConnection checks if the first packet of data is ClientHello, and checks if it was from a Cloak client
-// if it is from a Cloak client, it returns the ClientInfo with the decrypted fields. It doesn't check if the user
-// is authorised. It also returns a finisher callback function to be called when the caller wishes to proceed with
-// the handshake
-func PrepareConnection(firstPacket []byte, sta *State, conn net.Conn) (info ClientInfo, finisher func([]byte) error, err error) {
-	ch, err := parseClientHello(firstPacket)
-	if err != nil {
-		log.Debug(err)
-		err = ErrBadClientHello
-		return
-	}
-
-	if sta.registerRandom(ch.random) {
-		err = ErrReplay
-		return
-	}
-
-	var ai authenticationInfo
-	ai, err = unmarshalClientHello(ch, sta.staticPv)
-	if err != nil {
-		return
-	}
-	info, err = touchStone(ai, sta.Now)
-	if err != nil {
-		log.Debug(err)
-		err = ErrNotCloak
-		return
-	}
-	if _, ok := sta.ProxyBook[info.ProxyMethod]; !ok {
-		err = ErrBadProxyMethod
-		return
-	}
-
-	finisher = func(sessionKey []byte) error {
-		reply, err := composeReply(ch, ai.sharedSecret, sessionKey)
-		if err != nil {
-			return err
-		}
-		_, err = conn.Write(reply)
-		if err != nil {
-			go conn.Close()
-			return err
-		}
-		return nil
-	}
-	return
-}

internal/server/auth.go

@@ -1,12 +1,19 @@
 package server
 
 import (
+	"bufio"
 	"bytes"
+	"crypto/rand"
+	"encoding/base64"
 	"encoding/binary"
 	"errors"
 	"fmt"
 	"github.com/cbeuw/Cloak/internal/util"
+	"net"
+	"net/http"
 	"time"
+
+	log "github.com/sirupsen/logrus"
 )
 
 type ClientInfo struct {
@@ -30,11 +37,11 @@ const (
 var ErrInvalidPubKey = errors.New("public key has invalid format")
 var ErrCiphertextLength = errors.New("ciphertext has the wrong length")
 var ErrTimestampOutOfWindow = errors.New("timestamp is outside of the accepting window")
+var ErrUnreconisedProtocol = errors.New("unreconised protocol")
 
 // touchStone checks if a ClientHello came from a Cloak client by checking and decrypting the fields Cloak hides data in
 // It returns the ClientInfo, but it doesn't check if the UID is authorised
 func touchStone(ai authenticationInfo, now func() time.Time) (info ClientInfo, err error) {
-
 	var plaintext []byte
 	plaintext, err = util.AESGCMDecrypt(ai.nonce, ai.sharedSecret, ai.ciphertextWithTag)
 	if err != nil {
@@ -59,3 +66,99 @@ func touchStone(ai authenticationInfo, now func() time.Time) (info ClientInfo, e
 	info.SessionId = binary.BigEndian.Uint32(plaintext[37:41])
 	return
 }
+
+// PrepareConnection checks if the first packet of data is ClientHello or HTTP GET, and checks if it was from a Cloak client
+// if it is from a Cloak client, it returns the ClientInfo with the decrypted fields. It doesn't check if the user
+// is authorised. It also returns a finisher callback function to be called when the caller wishes to proceed with
+// the handshake
+func PrepareConnection(firstPacket []byte, sta *State, conn net.Conn) (info ClientInfo, finisher func([]byte) error, err error) {
+	var ai authenticationInfo
+	switch firstPacket[0] {
+	case 0x47:
+		var req *http.Request
+		req, err = http.ReadRequest(bufio.NewReader(bytes.NewBuffer(firstPacket)))
+		if err != nil {
+			err = fmt.Errorf("failed to parse first HTTP GET: %v", err)
+			return
+		}
+		var hiddenData []byte
+		hiddenData, err = base64.StdEncoding.DecodeString(req.Header.Get("hidden"))
+
+		ai, err = unmarshalHidden(hiddenData, sta.staticPv)
+		if err != nil {
+			err = fmt.Errorf("failed to unmarshal hidden data from WS into authenticationInfo: %v", err)
+			return
+		}
+
+		finisher = func(sessionKey []byte) error {
+			handler := newWsHandshakeHandler()
+
+			go http.Serve(newWsAcceptor(conn, firstPacket), handler)
+
+			<-handler.finished
+			conn = handler.conn
+			nonce := make([]byte, 12)
+			rand.Read(nonce)
+
+			// reply: [12 bytes nonce][32 bytes encrypted session key][16 bytes authentication tag]
+			encryptedKey, err := util.AESGCMEncrypt(nonce, ai.sharedSecret, sessionKey) // 32 + 16 = 48 bytes
+			if err != nil {
+				return fmt.Errorf("failed to encrypt reply: %v", err)
+			}
+			reply := append(nonce, encryptedKey...)
+			_, err = conn.Write(reply)
+			if err != nil {
+				go conn.Close()
+				return fmt.Errorf("failed to write reply: %v", err)
+			}
+			return nil
+		}
+	case 0x16:
+		var ch *ClientHello
+		ch, err = parseClientHello(firstPacket)
+		if err != nil {
+			log.Debug(err)
+			err = ErrBadClientHello
+			return
+		}
+
+		if sta.registerRandom(ch.random) {
+			err = ErrReplay
+			return
+		}
+
+		ai, err = unmarshalClientHello(ch, sta.staticPv)
+		if err != nil {
+			err = fmt.Errorf("failed to unmarshal ClientHello into authenticationInfo: %v", err)
+			return
+		}
+		finisher = func(sessionKey []byte) error {
+			reply, err := composeReply(ch, ai.sharedSecret, sessionKey)
+			if err != nil {
+				return fmt.Errorf("failed to compose TLS reply: %v", err)
+			}
+			_, err = conn.Write(reply)
+			if err != nil {
+				go conn.Close()
+				return fmt.Errorf("failed to write TLS reply: %v", err)
+			}
+			return nil
+		}
+	default:
+		err = ErrUnreconisedProtocol
+		return
+	}
+
+	info, err = touchStone(ai, sta.Now)
+	if err != nil {
+		log.Debug(err)
+		err = ErrNotCloak
+		return
+	}
+	if _, ok := sta.ProxyBook[info.ProxyMethod]; !ok {
+		err = ErrBadProxyMethod
+		return
+	}
+
+	return
+}

internal/server/websocket.go

@@ -0,0 +1,108 @@
+package server
+
+import (
+	"crypto"
+	"errors"
+	"fmt"
+	"github.com/cbeuw/Cloak/internal/ecdh"
+	"github.com/cbeuw/Cloak/internal/util"
+	"github.com/gorilla/websocket"
+	"net"
+	"net/http"
+
+	log "github.com/sirupsen/logrus"
+)
+
+type firstBuffedConn struct {
+	net.Conn
+	firstRead   bool
+	firstPacket []byte
+}
+
+func (c *firstBuffedConn) Read(buf []byte) (int, error) {
+	if !c.firstRead {
+		copy(buf, c.firstPacket)
+		n := len(c.firstPacket)
+		c.firstPacket = []byte{}
+		return n, nil
+	}
+	return c.Read(buf)
+}
+
+type wsAcceptor struct {
+	done bool
+	c    *firstBuffedConn
+}
+
+func newWsAcceptor(conn net.Conn, first []byte) *wsAcceptor {
+	f := make([]byte, len(first))
+	copy(f, first)
+	return &wsAcceptor{
+		c: &firstBuffedConn{Conn: conn, firstPacket: first},
+	}
+}
+
+func (w *wsAcceptor) Accept() (net.Conn, error) {
+	if w.done {
+		return nil, errors.New("already accepted")
+	}
+	w.done = true
+	return w.c, nil
+}
+
+func (w *wsAcceptor) Close() error {
+	w.done = true
+	return nil
+}
+
+func (w *wsAcceptor) Addr() net.Addr {
+	return w.c.LocalAddr()
+}
+
+type wsHandshakeHandler struct {
+	conn     net.Conn
+	finished chan struct{}
+}
+
+func newWsHandshakeHandler() *wsHandshakeHandler {
+	return &wsHandshakeHandler{finished: make(chan struct{})}
+}
+
+func (ws *wsHandshakeHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	upgrader := websocket.Upgrader{
+		ReadBufferSize:  16380,
+		WriteBufferSize: 16380,
+	}
+	c, err := upgrader.Upgrade(w, r, nil)
+	if err != nil {
+		log.Errorf("failed to upgrade connection to ws: %v", err)
+		return
+	}
+	ws.conn = &util.WebSocketConn{c}
+	ws.finished <- struct{}{}
+}
+
+var ErrBadGET = errors.New("non (or malformed) HTTP GET")
+
+func unmarshalHidden(hidden []byte, staticPv crypto.PrivateKey) (ai authenticationInfo, err error) {
+	if len(hidden) < 96 {
+		err = ErrBadGET
+		return
+	}
+	ephPub, ok := ecdh.Unmarshal(hidden[0:32])
+	if !ok {
+		err = ErrInvalidPubKey
+		return
+	}
+
+	ai.nonce = hidden[:12]
+
+	ai.sharedSecret = ecdh.GenerateSharedSecret(staticPv, ephPub)
+
+	ai.ciphertextWithTag = hidden[32:]
+	if len(ai.ciphertextWithTag) != 64 {
+		err = fmt.Errorf("%v: %v", ErrCiphertextLength, len(ai.ciphertextWithTag))
+		return
+	}
+	return
+}

internal/util/websocket.go

@@ -0,0 +1,39 @@
+package util
+
+import (
+	"github.com/gorilla/websocket"
+	"time"
+)
+
+type WebSocketConn struct {
+	*websocket.Conn
+}
+
+func (ws *WebSocketConn) Write(data []byte) (int, error) {
+	err := ws.WriteMessage(websocket.BinaryMessage, data)
+	if err != nil {
+		return 0, err
+	} else {
+		return len(data), nil
+	}
+}
+
+func (ws *WebSocketConn) Read(buf []byte) (int, error) {
+	_, r, err := ws.NextReader()
+	if err != nil {
+		return 0, err
+	}
+	return r.Read(buf)
+}
+
+func (ws *WebSocketConn) SetDeadline(t time.Time) error {
+	err := ws.SetReadDeadline(t)
+	if err != nil {
+		return err
+	}
+	err = ws.SetWriteDeadline(t)
+	if err != nil {
+		return err
+	}
+	return nil
+}