Removed transports from shapeshifter-dispatcher (now located in shapeshifter-transports)

7 files changed, 0 insertions, 2222 deletions

diff --git a/transports/obfs4/framing/framing.go b/transports/obfs4/framing/framing.go
deleted file mode 100644
index 9eaba69..0000000
--- a/transports/obfs4/framing/framing.go
+++ /dev/null
@@ -1,306 +0,0 @@
-/*
- * Copyright (c) 2014, Yawning Angel <yawning at torproject dot org>
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are met:
- *
- *  * Redistributions of source code must retain the above copyright notice,
- *    this list of conditions and the following disclaimer.
- *
- *  * Redistributions in binary form must reproduce the above copyright notice,
- *    this list of conditions and the following disclaimer in the documentation
- *    and/or other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
- * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
- * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
- * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
- * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
- * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
- * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
- * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
- * POSSIBILITY OF SUCH DAMAGE.
- */
-
-//
-// Package framing implements the obfs4 link framing and cryptography.
-//
-// The Encoder/Decoder shared secret format is:
-//    uint8_t[32] NaCl secretbox key
-//    uint8_t[16] NaCl Nonce prefix
-//    uint8_t[16] SipHash-2-4 key (used to obfsucate length)
-//    uint8_t[8]  SipHash-2-4 IV
-//
-// The frame format is:
-//   uint16_t length (obfsucated, big endian)
-//   NaCl secretbox (Poly1305/XSalsa20) containing:
-//     uint8_t[16] tag (Part of the secretbox construct)
-//     uint8_t[]   payload
-//
-// The length field is length of the NaCl secretbox XORed with the truncated
-// SipHash-2-4 digest ran in OFB mode.
-//
-//     Initialize K, IV[0] with values from the shared secret.
-//     On each packet, IV[n] = H(K, IV[n - 1])
-//     mask[n] = IV[n][0:2]
-//     obfsLen = length ^ mask[n]
-//
-// The NaCl secretbox (Poly1305/XSalsa20) nonce format is:
-//     uint8_t[24] prefix (Fixed)
-//     uint64_t    counter (Big endian)
-//
-// The counter is initialized to 1, and is incremented on each frame.  Since
-// the protocol is designed to be used over a reliable medium, the nonce is not
-// transmitted over the wire as both sides of the conversation know the prefix
-// and the initial counter value.  It is imperative that the counter does not
-// wrap, and sessions MUST terminate before 2^64 frames are sent.
-//
-package framing
-
-import (
-	"bytes"
-	"encoding/binary"
-	"errors"
-	"fmt"
-	"io"
-
-	"golang.org/x/crypto/nacl/secretbox"
-
-	"github.com/OperatorFoundation/obfs4/common/csrand"
-	"github.com/OperatorFoundation/obfs4/common/drbg"
-)
-
-const (
-	// MaximumSegmentLength is the length of the largest possible segment
-	// including overhead.
-	MaximumSegmentLength = 1500 - (40 + 12)
-
-	// FrameOverhead is the length of the framing overhead.
-	FrameOverhead = lengthLength + secretbox.Overhead
-
-	// MaximumFramePayloadLength is the length of the maximum allowed payload
-	// per frame.
-	MaximumFramePayloadLength = MaximumSegmentLength - FrameOverhead
-
-	// KeyLength is the length of the Encoder/Decoder secret key.
-	KeyLength = keyLength + noncePrefixLength + drbg.SeedLength
-
-	maxFrameLength = MaximumSegmentLength - lengthLength
-	minFrameLength = FrameOverhead - lengthLength
-
-	keyLength = 32
-
-	noncePrefixLength  = 16
-	nonceCounterLength = 8
-	nonceLength        = noncePrefixLength + nonceCounterLength
-
-	lengthLength = 2
-)
-
-// Error returned when Decoder.Decode() requires more data to continue.
-var ErrAgain = errors.New("framing: More data needed to decode")
-
-// Error returned when Decoder.Decode() failes to authenticate a frame.
-var ErrTagMismatch = errors.New("framing: Poly1305 tag mismatch")
-
-// Error returned when the NaCl secretbox nonce's counter wraps (FATAL).
-var ErrNonceCounterWrapped = errors.New("framing: Nonce counter wrapped")
-
-// InvalidPayloadLengthError is the error returned when Encoder.Encode()
-// rejects the payload length.
-type InvalidPayloadLengthError int
-
-func (e InvalidPayloadLengthError) Error() string {
-	return fmt.Sprintf("framing: Invalid payload length: %d", int(e))
-}
-
-type boxNonce struct {
-	prefix  [noncePrefixLength]byte
-	counter uint64
-}
-
-func (nonce *boxNonce) init(prefix []byte) {
-	if noncePrefixLength != len(prefix) {
-		panic(fmt.Sprintf("BUG: Nonce prefix length invalid: %d", len(prefix)))
-	}
-
-	copy(nonce.prefix[:], prefix)
-	nonce.counter = 1
-}
-
-func (nonce boxNonce) bytes(out *[nonceLength]byte) error {
-	// The security guarantee of Poly1305 is broken if a nonce is ever reused
-	// for a given key.  Detect this by checking for counter wraparound since
-	// we start each counter at 1.  If it ever happens that more than 2^64 - 1
-	// frames are transmitted over a given connection, support for rekeying
-	// will be neccecary, but that's unlikely to happen.
-	if nonce.counter == 0 {
-		return ErrNonceCounterWrapped
-	}
-
-	copy(out[:], nonce.prefix[:])
-	binary.BigEndian.PutUint64(out[noncePrefixLength:], nonce.counter)
-
-	return nil
-}
-
-// Encoder is a frame encoder instance.
-type Encoder struct {
-	key   [keyLength]byte
-	nonce boxNonce
-	drbg  *drbg.HashDrbg
-}
-
-// NewEncoder creates a new Encoder instance.  It must be supplied a slice
-// containing exactly KeyLength bytes of keying material.
-func NewEncoder(key []byte) *Encoder {
-	if len(key) != KeyLength {
-		panic(fmt.Sprintf("BUG: Invalid encoder key length: %d", len(key)))
-	}
-
-	encoder := new(Encoder)
-	copy(encoder.key[:], key[0:keyLength])
-	encoder.nonce.init(key[keyLength : keyLength+noncePrefixLength])
-	seed, err := drbg.SeedFromBytes(key[keyLength+noncePrefixLength:])
-	if err != nil {
-		panic(fmt.Sprintf("BUG: Failed to initialize DRBG: %s", err))
-	}
-	encoder.drbg, _ = drbg.NewHashDrbg(seed)
-
-	return encoder
-}
-
-// Encode encodes a single frame worth of payload and returns the encoded
-// length.  InvalidPayloadLengthError is recoverable, all other errors MUST be
-// treated as fatal and the session aborted.
-func (encoder *Encoder) Encode(frame, payload []byte) (n int, err error) {
-	payloadLen := len(payload)
-	if MaximumFramePayloadLength < payloadLen {
-		return 0, InvalidPayloadLengthError(payloadLen)
-	}
-	if len(frame) < payloadLen+FrameOverhead {
-		return 0, io.ErrShortBuffer
-	}
-
-	// Generate a new nonce.
-	var nonce [nonceLength]byte
-	if err = encoder.nonce.bytes(&nonce); err != nil {
-		return 0, err
-	}
-	encoder.nonce.counter++
-
-	// Encrypt and MAC payload.
-	box := secretbox.Seal(frame[:lengthLength], payload, &nonce, &encoder.key)
-
-	// Obfuscate the length.
-	length := uint16(len(box) - lengthLength)
-	lengthMask := encoder.drbg.NextBlock()
-	length ^= binary.BigEndian.Uint16(lengthMask)
-	binary.BigEndian.PutUint16(frame[:2], length)
-
-	// Return the frame.
-	return len(box), nil
-}
-
-// Decoder is a frame decoder instance.
-type Decoder struct {
-	key   [keyLength]byte
-	nonce boxNonce
-	drbg  *drbg.HashDrbg
-
-	nextNonce         [nonceLength]byte
-	nextLength        uint16
-	nextLengthInvalid bool
-}
-
-// NewDecoder creates a new Decoder instance.  It must be supplied a slice
-// containing exactly KeyLength bytes of keying material.
-func NewDecoder(key []byte) *Decoder {
-	if len(key) != KeyLength {
-		panic(fmt.Sprintf("BUG: Invalid decoder key length: %d", len(key)))
-	}
-
-	decoder := new(Decoder)
-	copy(decoder.key[:], key[0:keyLength])
-	decoder.nonce.init(key[keyLength : keyLength+noncePrefixLength])
-	seed, err := drbg.SeedFromBytes(key[keyLength+noncePrefixLength:])
-	if err != nil {
-		panic(fmt.Sprintf("BUG: Failed to initialize DRBG: %s", err))
-	}
-	decoder.drbg, _ = drbg.NewHashDrbg(seed)
-
-	return decoder
-}
-
-// Decode decodes a stream of data and returns the length if any.  ErrAgain is
-// a temporary failure, all other errors MUST be treated as fatal and the
-// session aborted.
-func (decoder *Decoder) Decode(data []byte, frames *bytes.Buffer) (int, error) {
-	// A length of 0 indicates that we do not know how big the next frame is
-	// going to be.
-	if decoder.nextLength == 0 {
-		// Attempt to pull out the next frame length.
-		if lengthLength > frames.Len() {
-			return 0, ErrAgain
-		}
-
-		// Remove the length field from the buffer.
-		var obfsLen [lengthLength]byte
-		_, err := io.ReadFull(frames, obfsLen[:])
-		if err != nil {
-			return 0, err
-		}
-
-		// Derive the nonce the peer used.
-		if err = decoder.nonce.bytes(&decoder.nextNonce); err != nil {
-			return 0, err
-		}
-
-		// Deobfuscate the length field.
-		length := binary.BigEndian.Uint16(obfsLen[:])
-		lengthMask := decoder.drbg.NextBlock()
-		length ^= binary.BigEndian.Uint16(lengthMask)
-		if maxFrameLength < length || minFrameLength > length {
-			// Per "Plaintext Recovery Attacks Against SSH" by
-			// Martin R. Albrecht, Kenneth G. Paterson and Gaven J. Watson,
-			// there are a class of attacks againt protocols that use similar
-			// sorts of framing schemes.
-			//
-			// While obfs4 should not allow plaintext recovery (CBC mode is
-			// not used), attempt to mitigate out of bound frame length errors
-			// by pretending that the length was a random valid range as per
-			// the countermeasure suggested by Denis Bider in section 6 of the
-			// paper.
-
-			decoder.nextLengthInvalid = true
-			length = uint16(csrand.IntRange(minFrameLength, maxFrameLength))
-		}
-		decoder.nextLength = length
-	}
-
-	if int(decoder.nextLength) > frames.Len() {
-		return 0, ErrAgain
-	}
-
-	// Unseal the frame.
-	var box [maxFrameLength]byte
-	n, err := io.ReadFull(frames, box[:decoder.nextLength])
-	if err != nil {
-		return 0, err
-	}
-	out, ok := secretbox.Open(data[:0], box[:n], &decoder.nextNonce, &decoder.key)
-	if !ok || decoder.nextLengthInvalid {
-		// When a random length is used (on length error) the tag should always
-		// mismatch, but be paranoid.
-		return 0, ErrTagMismatch
-	}
-
-	// Clean up and prepare for the next frame.
-	decoder.nextLength = 0
-	decoder.nonce.counter++
-
-	return len(out), nil
-}
diff --git a/transports/obfs4/framing/framing_test.go b/transports/obfs4/framing/framing_test.go
deleted file mode 100644
index 03e0d3b..0000000
--- a/transports/obfs4/framing/framing_test.go
+++ /dev/null
@@ -1,169 +0,0 @@
-/*
- * Copyright (c) 2014, Yawning Angel <yawning at torproject dot org>
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are met:
- *
- *  * Redistributions of source code must retain the above copyright notice,
- *    this list of conditions and the following disclaimer.
- *
- *  * Redistributions in binary form must reproduce the above copyright notice,
- *    this list of conditions and the following disclaimer in the documentation
- *    and/or other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
- * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
- * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
- * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
- * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
- * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
- * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
- * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
- * POSSIBILITY OF SUCH DAMAGE.
- */
-
-package framing
-
-import (
-	"bytes"
-	"crypto/rand"
-	"testing"
-)
-
-func generateRandomKey() []byte {
-	key := make([]byte, KeyLength)
-
-	_, err := rand.Read(key)
-	if err != nil {
-		panic(err)
-	}
-
-	return key
-}
-
-func newEncoder(t *testing.T) *Encoder {
-	// Generate a key to use.
-	key := generateRandomKey()
-
-	encoder := NewEncoder(key)
-	if encoder == nil {
-		t.Fatalf("NewEncoder returned nil")
-	}
-
-	return encoder
-}
-
-// TestNewEncoder tests the Encoder ctor.
-func TestNewEncoder(t *testing.T) {
-	encoder := newEncoder(t)
-	_ = encoder
-}
-
-// TestEncoder_Encode tests Encoder.Encode.
-func TestEncoder_Encode(t *testing.T) {
-	encoder := newEncoder(t)
-
-	buf := make([]byte, MaximumFramePayloadLength)
-	_, _ = rand.Read(buf) // YOLO
-	for i := 0; i <= MaximumFramePayloadLength; i++ {
-		var frame [MaximumSegmentLength]byte
-		n, err := encoder.Encode(frame[:], buf[0:i])
-		if err != nil {
-			t.Fatalf("Encoder.encode([%d]byte), failed: %s", i, err)
-		}
-		if n != i+FrameOverhead {
-			t.Fatalf("Unexpected encoded framesize: %d, expecting %d", n, i+
-				FrameOverhead)
-		}
-	}
-}
-
-// TestEncoder_Encode_Oversize tests oversized frame rejection.
-func TestEncoder_Encode_Oversize(t *testing.T) {
-	encoder := newEncoder(t)
-
-	var frame [MaximumSegmentLength]byte
-	var buf [MaximumFramePayloadLength + 1]byte
-	_, _ = rand.Read(buf[:]) // YOLO
-	_, err := encoder.Encode(frame[:], buf[:])
-	if _, ok := err.(InvalidPayloadLengthError); !ok {
-		t.Error("Encoder.encode() returned unexpected error:", err)
-	}
-}
-
-// TestNewDecoder tests the Decoder ctor.
-func TestNewDecoder(t *testing.T) {
-	key := generateRandomKey()
-	decoder := NewDecoder(key)
-	if decoder == nil {
-		t.Fatalf("NewDecoder returned nil")
-	}
-}
-
-// TestDecoder_Decode tests Decoder.Decode.
-func TestDecoder_Decode(t *testing.T) {
-	key := generateRandomKey()
-
-	encoder := NewEncoder(key)
-	decoder := NewDecoder(key)
-
-	var buf [MaximumFramePayloadLength]byte
-	_, _ = rand.Read(buf[:]) // YOLO
-	for i := 0; i <= MaximumFramePayloadLength; i++ {
-		var frame [MaximumSegmentLength]byte
-		encLen, err := encoder.Encode(frame[:], buf[0:i])
-		if err != nil {
-			t.Fatalf("Encoder.encode([%d]byte), failed: %s", i, err)
-		}
-		if encLen != i+FrameOverhead {
-			t.Fatalf("Unexpected encoded framesize: %d, expecting %d", encLen,
-				i+FrameOverhead)
-		}
-
-		var decoded [MaximumFramePayloadLength]byte
-
-		decLen, err := decoder.Decode(decoded[:], bytes.NewBuffer(frame[:encLen]))
-		if err != nil {
-			t.Fatalf("Decoder.decode([%d]byte), failed: %s", i, err)
-		}
-		if decLen != i {
-			t.Fatalf("Unexpected decoded framesize: %d, expecting %d",
-				decLen, i)
-		}
-
-		if 0 != bytes.Compare(decoded[:decLen], buf[:i]) {
-			t.Fatalf("Frame %d does not match encoder input", i)
-		}
-	}
-}
-
-// BencharkEncoder_Encode benchmarks Encoder.Encode processing 1 MiB
-// of payload.
-func BenchmarkEncoder_Encode(b *testing.B) {
-	var chopBuf [MaximumFramePayloadLength]byte
-	var frame [MaximumSegmentLength]byte
-	payload := make([]byte, 1024*1024)
-	encoder := NewEncoder(generateRandomKey())
-	b.ResetTimer()
-
-	for i := 0; i < b.N; i++ {
-		transfered := 0
-		buffer := bytes.NewBuffer(payload)
-		for 0 < buffer.Len() {
-			n, err := buffer.Read(chopBuf[:])
-			if err != nil {
-				b.Fatal("buffer.Read() failed:", err)
-			}
-
-			n, err = encoder.Encode(frame[:], chopBuf[:n])
-			transfered += n - FrameOverhead
-		}
-		if transfered != len(payload) {
-			b.Fatalf("Transfered length mismatch: %d != %d", transfered,
-				len(payload))
-		}
-	}
-}
diff --git a/transports/obfs4/handshake_ntor.go b/transports/obfs4/handshake_ntor.go
deleted file mode 100644
index ed7c114..0000000
--- a/transports/obfs4/handshake_ntor.go
+++ /dev/null
@@ -1,425 +0,0 @@
-/*
- * Copyright (c) 2014, Yawning Angel <yawning at torproject dot org>
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are met:
- *
- *  * Redistributions of source code must retain the above copyright notice,
- *    this list of conditions and the following disclaimer.
- *
- *  * Redistributions in binary form must reproduce the above copyright notice,
- *    this list of conditions and the following disclaimer in the documentation
- *    and/or other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
- * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
- * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
- * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
- * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
- * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
- * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
- * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
- * POSSIBILITY OF SUCH DAMAGE.
- */
-
-package obfs4
-
-import (
-	"bytes"
-	"crypto/hmac"
-	"crypto/sha256"
-	"encoding/hex"
-	"errors"
-	"fmt"
-	"hash"
-	"strconv"
-	"time"
-
-	"github.com/OperatorFoundation/obfs4/common/csrand"
-	"github.com/OperatorFoundation/obfs4/common/ntor"
-	"github.com/OperatorFoundation/obfs4/common/replayfilter"
-	"github.com/OperatorFoundation/obfs4/transports/obfs4/framing"
-)
-
-const (
-	maxHandshakeLength = 8192
-
-	clientMinPadLength = (serverMinHandshakeLength + inlineSeedFrameLength) -
-		clientMinHandshakeLength
-	clientMaxPadLength       = maxHandshakeLength - clientMinHandshakeLength
-	clientMinHandshakeLength = ntor.RepresentativeLength + markLength + macLength
-
-	serverMinPadLength = 0
-	serverMaxPadLength = maxHandshakeLength - (serverMinHandshakeLength +
-		inlineSeedFrameLength)
-	serverMinHandshakeLength = ntor.RepresentativeLength + ntor.AuthLength +
-		markLength + macLength
-
-	markLength = sha256.Size / 2
-	macLength  = sha256.Size / 2
-
-	inlineSeedFrameLength = framing.FrameOverhead + packetOverhead + seedPacketPayloadLength
-)
-
-// ErrMarkNotFoundYet is the error returned when the obfs4 handshake is
-// incomplete and requires more data to continue.  This error is non-fatal and
-// is the equivalent to EAGAIN/EWOULDBLOCK.
-var ErrMarkNotFoundYet = errors.New("handshake: M_[C,S] not found yet")
-
-// ErrInvalidHandshake is the error returned when the obfs4 handshake fails due
-// to the peer not sending the correct mark.  This error is fatal and the
-// connection MUST be dropped.
-var ErrInvalidHandshake = errors.New("handshake: Failed to find M_[C,S]")
-
-// ErrReplayedHandshake is the error returned when the obfs4 handshake fails
-// due it being replayed.  This error is fatal and the connection MUST be
-// dropped.
-var ErrReplayedHandshake = errors.New("handshake: Replay detected")
-
-// ErrNtorFailed is the error returned when the ntor handshake fails.  This
-// error is fatal and the connection MUST be dropped.
-var ErrNtorFailed = errors.New("handshake: ntor handshake failure")
-
-// InvalidMacError is the error returned when the handshake MACs do not match.
-// This error is fatal and the connection MUST be dropped.
-type InvalidMacError struct {
-	Derived  []byte
-	Received []byte
-}
-
-func (e *InvalidMacError) Error() string {
-	return fmt.Sprintf("handshake: MAC mismatch: Dervied: %s Received: %s.",
-		hex.EncodeToString(e.Derived), hex.EncodeToString(e.Received))
-}
-
-// InvalidAuthError is the error returned when the ntor AUTH tags do not match.
-// This error is fatal and the connection MUST be dropped.
-type InvalidAuthError struct {
-	Derived  *ntor.Auth
-	Received *ntor.Auth
-}
-
-func (e *InvalidAuthError) Error() string {
-	return fmt.Sprintf("handshake: ntor AUTH mismatch: Derived: %s Received:%s.",
-		hex.EncodeToString(e.Derived.Bytes()[:]),
-		hex.EncodeToString(e.Received.Bytes()[:]))
-}
-
-type clientHandshake struct {
-	keypair        *ntor.Keypair
-	nodeID         *ntor.NodeID
-	serverIdentity *ntor.PublicKey
-	epochHour      []byte
-
-	padLen int
-	mac    hash.Hash
-
-	serverRepresentative *ntor.Representative
-	serverAuth           *ntor.Auth
-	serverMark           []byte
-}
-
-func newClientHandshake(nodeID *ntor.NodeID, serverIdentity *ntor.PublicKey, sessionKey *ntor.Keypair) *clientHandshake {
-	hs := new(clientHandshake)
-	hs.keypair = sessionKey
-	hs.nodeID = nodeID
-	hs.serverIdentity = serverIdentity
-	hs.padLen = csrand.IntRange(clientMinPadLength, clientMaxPadLength)
-	hs.mac = hmac.New(sha256.New, append(hs.serverIdentity.Bytes()[:], hs.nodeID.Bytes()[:]...))
-
-	return hs
-}
-
-func (hs *clientHandshake) generateHandshake() ([]byte, error) {
-	var buf bytes.Buffer
-
-	hs.mac.Reset()
-	hs.mac.Write(hs.keypair.Representative().Bytes()[:])
-	mark := hs.mac.Sum(nil)[:markLength]
-
-	// The client handshake is X | P_C | M_C | MAC(X | P_C | M_C | E) where:
-	//  * X is the client's ephemeral Curve25519 public key representative.
-	//  * P_C is [clientMinPadLength,clientMaxPadLength] bytes of random padding.
-	//  * M_C is HMAC-SHA256-128(serverIdentity | NodeID, X)
-	//  * MAC is HMAC-SHA256-128(serverIdentity | NodeID, X .... E)
-	//  * E is the string representation of the number of hours since the UNIX
-	//    epoch.
-
-	// Generate the padding
-	pad, err := makePad(hs.padLen)
-	if err != nil {
-		return nil, err
-	}
-
-	// Write X, P_C, M_C.
-	buf.Write(hs.keypair.Representative().Bytes()[:])
-	buf.Write(pad)
-	buf.Write(mark)
-
-	// Calculate and write the MAC.
-	hs.mac.Reset()
-	hs.mac.Write(buf.Bytes())
-	hs.epochHour = []byte(strconv.FormatInt(getEpochHour(), 10))
-	hs.mac.Write(hs.epochHour)
-	buf.Write(hs.mac.Sum(nil)[:macLength])
-
-	return buf.Bytes(), nil
-}
-
-func (hs *clientHandshake) parseServerHandshake(resp []byte) (int, []byte, error) {
-	// No point in examining the data unless the miminum plausible response has
-	// been received.
-	if serverMinHandshakeLength > len(resp) {
-		return 0, nil, ErrMarkNotFoundYet
-	}
-
-	if hs.serverRepresentative == nil || hs.serverAuth == nil {
-		// Pull out the representative/AUTH. (XXX: Add ctors to ntor)
-		hs.serverRepresentative = new(ntor.Representative)
-		copy(hs.serverRepresentative.Bytes()[:], resp[0:ntor.RepresentativeLength])
-		hs.serverAuth = new(ntor.Auth)
-		copy(hs.serverAuth.Bytes()[:], resp[ntor.RepresentativeLength:])
-
-		// Derive the mark.
-		hs.mac.Reset()
-		hs.mac.Write(hs.serverRepresentative.Bytes()[:])
-		hs.serverMark = hs.mac.Sum(nil)[:markLength]
-	}
-
-	// Attempt to find the mark + MAC.
-	pos := findMarkMac(hs.serverMark, resp, ntor.RepresentativeLength+ntor.AuthLength+serverMinPadLength,
-		maxHandshakeLength, false)
-	if pos == -1 {
-		if len(resp) >= maxHandshakeLength {
-			return 0, nil, ErrInvalidHandshake
-		}
-		return 0, nil, ErrMarkNotFoundYet
-	}
-
-	// Validate the MAC.
-	hs.mac.Reset()
-	hs.mac.Write(resp[:pos+markLength])
-	hs.mac.Write(hs.epochHour)
-	macCmp := hs.mac.Sum(nil)[:macLength]
-	macRx := resp[pos+markLength : pos+markLength+macLength]
-	if !hmac.Equal(macCmp, macRx) {
-		return 0, nil, &InvalidMacError{macCmp, macRx}
-	}
-
-	// Complete the handshake.
-	serverPublic := hs.serverRepresentative.ToPublic()
-	ok, seed, auth := ntor.ClientHandshake(hs.keypair, serverPublic,
-		hs.serverIdentity, hs.nodeID)
-	if !ok {
-		return 0, nil, ErrNtorFailed
-	}
-	if !ntor.CompareAuth(auth, hs.serverAuth.Bytes()[:]) {
-		return 0, nil, &InvalidAuthError{auth, hs.serverAuth}
-	}
-
-	return pos + markLength + macLength, seed.Bytes()[:], nil
-}
-
-type serverHandshake struct {
-	keypair        *ntor.Keypair
-	nodeID         *ntor.NodeID
-	serverIdentity *ntor.Keypair
-	epochHour      []byte
-	serverAuth     *ntor.Auth
-
-	padLen int
-	mac    hash.Hash
-
-	clientRepresentative *ntor.Representative
-	clientMark           []byte
-}
-
-func newServerHandshake(nodeID *ntor.NodeID, serverIdentity *ntor.Keypair, sessionKey *ntor.Keypair) *serverHandshake {
-	hs := new(serverHandshake)
-	hs.keypair = sessionKey
-	hs.nodeID = nodeID
-	hs.serverIdentity = serverIdentity
-	hs.padLen = csrand.IntRange(serverMinPadLength, serverMaxPadLength)
-	hs.mac = hmac.New(sha256.New, append(hs.serverIdentity.Public().Bytes()[:], hs.nodeID.Bytes()[:]...))
-
-	return hs
-}
-
-func (hs *serverHandshake) parseClientHandshake(filter *replayfilter.ReplayFilter, resp []byte) ([]byte, error) {
-	// No point in examining the data unless the miminum plausible response has
-	// been received.
-	if clientMinHandshakeLength > len(resp) {
-		return nil, ErrMarkNotFoundYet
-	}
-
-	if hs.clientRepresentative == nil {
-		// Pull out the representative/AUTH. (XXX: Add ctors to ntor)
-		hs.clientRepresentative = new(ntor.Representative)
-		copy(hs.clientRepresentative.Bytes()[:], resp[0:ntor.RepresentativeLength])
-
-		// Derive the mark.
-		hs.mac.Reset()
-		hs.mac.Write(hs.clientRepresentative.Bytes()[:])
-		hs.clientMark = hs.mac.Sum(nil)[:markLength]
-	}
-
-	// Attempt to find the mark + MAC.
-	pos := findMarkMac(hs.clientMark, resp, ntor.RepresentativeLength+clientMinPadLength,
-		maxHandshakeLength, true)
-	if pos == -1 {
-		if len(resp) >= maxHandshakeLength {
-			return nil, ErrInvalidHandshake
-		}
-		return nil, ErrMarkNotFoundYet
-	}
-
-	// Validate the MAC.
-	macFound := false
-	for _, off := range []int64{0, -1, 1} {
-		// Allow epoch to be off by up to a hour in either direction.
-		epochHour := []byte(strconv.FormatInt(getEpochHour()+int64(off), 10))
-		hs.mac.Reset()
-		hs.mac.Write(resp[:pos+markLength])
-		hs.mac.Write(epochHour)
-		macCmp := hs.mac.Sum(nil)[:macLength]
-		macRx := resp[pos+markLength : pos+markLength+macLength]
-		if hmac.Equal(macCmp, macRx) {
-			// Ensure that this handshake has not been seen previously.
-			if filter.TestAndSet(time.Now(), macRx) {
-				// The client either happened to generate exactly the same
-				// session key and padding, or someone is replaying a previous
-				// handshake.  In either case, fuck them.
-				return nil, ErrReplayedHandshake
-			}
-
-			macFound = true
-			hs.epochHour = epochHour
-
-			// We could break out here, but in the name of reducing timing
-			// variation, evaluate all 3 MACs.
-		}
-	}
-	if !macFound {
-		// This probably should be an InvalidMacError, but conveying the 3 MACS
-		// that would be accepted is annoying so just return a generic fatal
-		// failure.
-		return nil, ErrInvalidHandshake
-	}
-
-	// Client should never sent trailing garbage.
-	if len(resp) != pos+markLength+macLength {
-		return nil, ErrInvalidHandshake
-	}
-
-	clientPublic := hs.clientRepresentative.ToPublic()
-	ok, seed, auth := ntor.ServerHandshake(clientPublic, hs.keypair,
-		hs.serverIdentity, hs.nodeID)
-	if !ok {
-		return nil, ErrNtorFailed
-	}
-	hs.serverAuth = auth
-
-	return seed.Bytes()[:], nil
-}
-
-func (hs *serverHandshake) generateHandshake() ([]byte, error) {
-	var buf bytes.Buffer
-
-	hs.mac.Reset()
-	hs.mac.Write(hs.keypair.Representative().Bytes()[:])
-	mark := hs.mac.Sum(nil)[:markLength]
-
-	// The server handshake is Y | AUTH | P_S | M_S | MAC(Y | AUTH | P_S | M_S | E) where:
-	//  * Y is the server's ephemeral Curve25519 public key representative.
-	//  * AUTH is the ntor handshake AUTH value.
-	//  * P_S is [serverMinPadLength,serverMaxPadLength] bytes of random padding.
-	//  * M_S is HMAC-SHA256-128(serverIdentity | NodeID, Y)
-	//  * MAC is HMAC-SHA256-128(serverIdentity | NodeID, Y .... E)
-	//  * E is the string representation of the number of hours since the UNIX
-	//    epoch.
-
-	// Generate the padding
-	pad, err := makePad(hs.padLen)
-	if err != nil {
-		return nil, err
-	}
-
-	// Write Y, AUTH, P_S, M_S.
-	buf.Write(hs.keypair.Representative().Bytes()[:])
-	buf.Write(hs.serverAuth.Bytes()[:])
-	buf.Write(pad)
-	buf.Write(mark)
-
-	// Calculate and write the MAC.
-	hs.mac.Reset()
-	hs.mac.Write(buf.Bytes())
-	hs.epochHour = []byte(strconv.FormatInt(getEpochHour(), 10))
-	hs.mac.Write(hs.epochHour)
-	buf.Write(hs.mac.Sum(nil)[:macLength])
-
-	return buf.Bytes(), nil
-}
-
-// getEpochHour returns the number of hours since the UNIX epoch.
-func getEpochHour() int64 {
-	return time.Now().Unix() / 3600
-}
-
-func findMarkMac(mark, buf []byte, startPos, maxPos int, fromTail bool) (pos int) {
-	if len(mark) != markLength {
-		panic(fmt.Sprintf("BUG: Invalid mark length: %d", len(mark)))
-	}
-
-	endPos := len(buf)
-	if startPos > len(buf) {
-		return -1
-	}
-	if endPos > maxPos {
-		endPos = maxPos
-	}
-	if endPos-startPos < markLength+macLength {
-		return -1
-	}
-
-	if fromTail {
-		// The server can optimize the search process by only examining the
-		// tail of the buffer.  The client can't send valid data past M_C |
-		// MAC_C as it does not have the server's public key yet.
-		pos = endPos - (markLength + macLength)
-		if !hmac.Equal(buf[pos:pos+markLength], mark) {
-			return -1
-		}
-
-		return
-	}
-
-	// The client has to actually do a substring search since the server can
-	// and will send payload trailing the response.
-	//
-	// XXX: bytes.Index() uses a naive search, which kind of sucks.
-	pos = bytes.Index(buf[startPos:endPos], mark)
-	if pos == -1 {
-		return -1
-	}
-
-	// Ensure that there is enough trailing data for the MAC.
-	if startPos+pos+markLength+macLength > endPos {
-		return -1
-	}
-
-	// Return the index relative to the start of the slice.
-	pos += startPos
-	return
-}
-
-func makePad(padLen int) ([]byte, error) {
-	pad := make([]byte, padLen)
-	if err := csrand.Bytes(pad); err != nil {
-		return nil, err
-	}
-
-	return pad, nil
-}
diff --git a/transports/obfs4/handshake_ntor_test.go b/transports/obfs4/handshake_ntor_test.go
deleted file mode 100644
index 04afcef..0000000
--- a/transports/obfs4/handshake_ntor_test.go
+++ /dev/null
@@ -1,248 +0,0 @@
-/*
- * Copyright (c) 2014, Yawning Angel <yawning at torproject dot org>
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are met:
- *
- *  * Redistributions of source code must retain the above copyright notice,
- *    this list of conditions and the following disclaimer.
- *
- *  * Redistributions in binary form must reproduce the above copyright notice,
- *    this list of conditions and the following disclaimer in the documentation
- *    and/or other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
- * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
- * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
- * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
- * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
- * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
- * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
- * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
- * POSSIBILITY OF SUCH DAMAGE.
- */
-
-package obfs4
-
-import (
-	"bytes"
-	"testing"
-
-	"github.com/OperatorFoundation/obfs4/common/ntor"
-	"github.com/OperatorFoundation/obfs4/common/replayfilter"
-)
-
-func TestHandshakeNtorClient(t *testing.T) {
-	// Generate the server node id and id keypair, and ephemeral session keys.
-	nodeID, _ := ntor.NewNodeID([]byte("\x00\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f\x10\x11\x12\x13"))
-	idKeypair, _ := ntor.NewKeypair(false)
-	serverFilter, _ := replayfilter.New(replayTTL)
-	clientKeypair, err := ntor.NewKeypair(true)
-	if err != nil {
-		t.Fatalf("client: ntor.NewKeypair failed: %s", err)
-	}
-	serverKeypair, err := ntor.NewKeypair(true)
-	if err != nil {
-		t.Fatalf("server: ntor.NewKeypair failed: %s", err)
-	}
-
-	// Test client handshake padding.
-	for l := clientMinPadLength; l <= clientMaxPadLength; l++ {
-		// Generate the client state and override the pad length.
-		clientHs := newClientHandshake(nodeID, idKeypair.Public(), clientKeypair)
-		clientHs.padLen = l
-
-		// Generate what the client will send to the server.
-		clientBlob, err := clientHs.generateHandshake()
-		if err != nil {
-			t.Fatalf("[%d:0] clientHandshake.generateHandshake() failed: %s", l, err)
-		}
-		if len(clientBlob) > maxHandshakeLength {
-			t.Fatalf("[%d:0] Generated client body is oversized: %d", l, len(clientBlob))
-		}
-		if len(clientBlob) < clientMinHandshakeLength {
-			t.Fatalf("[%d:0] Generated client body is undersized: %d", l, len(clientBlob))
-		}
-		if len(clientBlob) != clientMinHandshakeLength+l {
-			t.Fatalf("[%d:0] Generated client body incorrect size: %d", l, len(clientBlob))
-		}
-
-		// Generate the server state and override the pad length.
-		serverHs := newServerHandshake(nodeID, idKeypair, serverKeypair)
-		serverHs.padLen = serverMinPadLength
-
-		// Parse the client handshake message.
-		serverSeed, err := serverHs.parseClientHandshake(serverFilter, clientBlob)
-		if err != nil {
-			t.Fatalf("[%d:0] serverHandshake.parseClientHandshake() failed: %s", l, err)
-		}
-
-		// Genrate what the server will send to the client.
-		serverBlob, err := serverHs.generateHandshake()
-		if err != nil {
-			t.Fatalf("[%d:0]: serverHandshake.generateHandshake() failed: %s", l, err)
-		}
-
-		// Parse the server handshake message.
-		clientHs.serverRepresentative = nil
-		n, clientSeed, err := clientHs.parseServerHandshake(serverBlob)
-		if err != nil {
-			t.Fatalf("[%d:0] clientHandshake.parseServerHandshake() failed: %s", l, err)
-		}
-		if n != len(serverBlob) {
-			t.Fatalf("[%d:0] clientHandshake.parseServerHandshake() has bytes remaining: %d", l, n)
-		}
-
-		// Ensure the derived shared secret is the same.
-		if 0 != bytes.Compare(clientSeed, serverSeed) {
-			t.Fatalf("[%d:0] client/server seed mismatch", l)
-		}
-	}
-
-	// Test oversized client padding.
-	clientHs := newClientHandshake(nodeID, idKeypair.Public(), clientKeypair)
-	if err != nil {
-		t.Fatalf("newClientHandshake failed: %s", err)
-	}
-	clientHs.padLen = clientMaxPadLength + 1
-	clientBlob, err := clientHs.generateHandshake()
-	if err != nil {
-		t.Fatalf("clientHandshake.generateHandshake() (forced oversize) failed: %s", err)
-	}
-	serverHs := newServerHandshake(nodeID, idKeypair, serverKeypair)
-	_, err = serverHs.parseClientHandshake(serverFilter, clientBlob)
-	if err == nil {
-		t.Fatalf("serverHandshake.parseClientHandshake() succeded (oversized)")
-	}
-
-	// Test undersized client padding.
-	clientHs.padLen = clientMinPadLength - 1
-	clientBlob, err = clientHs.generateHandshake()
-	if err != nil {
-		t.Fatalf("clientHandshake.generateHandshake() (forced undersize) failed: %s", err)
-	}
-	serverHs = newServerHandshake(nodeID, idKeypair, serverKeypair)
-	_, err = serverHs.parseClientHandshake(serverFilter, clientBlob)
-	if err == nil {
-		t.Fatalf("serverHandshake.parseClientHandshake() succeded (undersized)")
-	}
-}
-
-func TestHandshakeNtorServer(t *testing.T) {
-	// Generate the server node id and id keypair, and ephemeral session keys.
-	nodeID, _ := ntor.NewNodeID([]byte("\x00\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f\x10\x11\x12\x13"))
-	idKeypair, _ := ntor.NewKeypair(false)
-	serverFilter, _ := replayfilter.New(replayTTL)
-	clientKeypair, err := ntor.NewKeypair(true)
-	if err != nil {
-		t.Fatalf("client: ntor.NewKeypair failed: %s", err)
-	}
-	serverKeypair, err := ntor.NewKeypair(true)
-	if err != nil {
-		t.Fatalf("server: ntor.NewKeypair failed: %s", err)
-	}
-
-	// Test server handshake padding.
-	for l := serverMinPadLength; l <= serverMaxPadLength+inlineSeedFrameLength; l++ {
-		// Generate the client state and override the pad length.
-		clientHs := newClientHandshake(nodeID, idKeypair.Public(), clientKeypair)
-		clientHs.padLen = clientMinPadLength
-
-		// Generate what the client will send to the server.
-		clientBlob, err := clientHs.generateHandshake()
-		if err != nil {
-			t.Fatalf("[%d:1] clientHandshake.generateHandshake() failed: %s", l, err)
-		}
-		if len(clientBlob) > maxHandshakeLength {
-			t.Fatalf("[%d:1] Generated client body is oversized: %d", l, len(clientBlob))
-		}
-
-		// Generate the server state and override the pad length.
-		serverHs := newServerHandshake(nodeID, idKeypair, serverKeypair)
-		serverHs.padLen = l
-
-		// Parse the client handshake message.
-		serverSeed, err := serverHs.parseClientHandshake(serverFilter, clientBlob)
-		if err != nil {
-			t.Fatalf("[%d:1] serverHandshake.parseClientHandshake() failed: %s", l, err)
-		}
-
-		// Genrate what the server will send to the client.
-		serverBlob, err := serverHs.generateHandshake()
-		if err != nil {
-			t.Fatalf("[%d:1]: serverHandshake.generateHandshake() failed: %s", l, err)
-		}
-
-		// Parse the server handshake message.
-		n, clientSeed, err := clientHs.parseServerHandshake(serverBlob)
-		if err != nil {
-			t.Fatalf("[%d:1] clientHandshake.parseServerHandshake() failed: %s", l, err)
-		}
-		if n != len(serverBlob) {
-			t.Fatalf("[%d:1] clientHandshake.parseServerHandshake() has bytes remaining: %d", l, n)
-		}
-
-		// Ensure the derived shared secret is the same.
-		if 0 != bytes.Compare(clientSeed, serverSeed) {
-			t.Fatalf("[%d:1] client/server seed mismatch", l)
-		}
-	}
-
-	// Test oversized client padding.
-	clientHs := newClientHandshake(nodeID, idKeypair.Public(), clientKeypair)
-	if err != nil {
-		t.Fatalf("newClientHandshake failed: %s", err)
-	}
-	clientHs.padLen = clientMaxPadLength + 1
-	clientBlob, err := clientHs.generateHandshake()
-	if err != nil {
-		t.Fatalf("clientHandshake.generateHandshake() (forced oversize) failed: %s", err)
-	}
-	serverHs := newServerHandshake(nodeID, idKeypair, serverKeypair)
-	_, err = serverHs.parseClientHandshake(serverFilter, clientBlob)
-	if err == nil {
-		t.Fatalf("serverHandshake.parseClientHandshake() succeded (oversized)")
-	}
-
-	// Test undersized client padding.
-	clientHs.padLen = clientMinPadLength - 1
-	clientBlob, err = clientHs.generateHandshake()
-	if err != nil {
-		t.Fatalf("clientHandshake.generateHandshake() (forced undersize) failed: %s", err)
-	}
-	serverHs = newServerHandshake(nodeID, idKeypair, serverKeypair)
-	_, err = serverHs.parseClientHandshake(serverFilter, clientBlob)
-	if err == nil {
-		t.Fatalf("serverHandshake.parseClientHandshake() succeded (undersized)")
-	}
-
-	// Test oversized server padding.
-	//
-	// NB: serverMaxPadLength isn't the real maxPadLength that triggers client
-	// rejection, because the implementation is written with the asusmption
-	// that the PRNG_SEED is also inlined with the response.  Thus the client
-	// actually accepts longer padding.  The server handshake test and this
-	// test adjust around that.
-	clientHs.padLen = clientMinPadLength
-	clientBlob, err = clientHs.generateHandshake()
-	if err != nil {
-		t.Fatalf("clientHandshake.generateHandshake() failed: %s", err)
-	}
-	serverHs = newServerHandshake(nodeID, idKeypair, serverKeypair)
-	serverHs.padLen = serverMaxPadLength + inlineSeedFrameLength + 1
-	_, err = serverHs.parseClientHandshake(serverFilter, clientBlob)
-	if err != nil {
-		t.Fatalf("serverHandshake.parseClientHandshake() failed: %s", err)
-	}
-	serverBlob, err := serverHs.generateHandshake()
-	if err != nil {
-		t.Fatalf("serverHandshake.generateHandshake() (forced oversize) failed: %s", err)
-	}
-	_, _, err = clientHs.parseServerHandshake(serverBlob)
-	if err == nil {
-		t.Fatalf("clientHandshake.parseServerHandshake() succeded (oversized)")
-	}
-}
diff --git a/transports/obfs4/obfs4.go b/transports/obfs4/obfs4.go
deleted file mode 100644
index 269e1c6..0000000
--- a/transports/obfs4/obfs4.go
+++ /dev/null
@@ -1,646 +0,0 @@
-/*
- * Copyright (c) 2014, Yawning Angel <yawning at torproject dot org>
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are met:
- *
- *  * Redistributions of source code must retain the above copyright notice,
- *    this list of conditions and the following disclaimer.
- *
- *  * Redistributions in binary form must reproduce the above copyright notice,
- *    this list of conditions and the following disclaimer in the documentation
- *    and/or other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
- * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
- * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
- * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
- * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
- * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
- * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
- * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
- * POSSIBILITY OF SUCH DAMAGE.
- */
-
-// Package obfs4 provides an implementation of the Tor Project's obfs4
-// obfuscation protocol.
-package obfs4
-
-import (
-	"bytes"
-	"crypto/sha256"
-	"flag"
-	"fmt"
-	"math/rand"
-	"net"
-	"strconv"
-	"syscall"
-	"time"
-
-	"git.torproject.org/pluggable-transports/goptlib.git"
-	"github.com/OperatorFoundation/obfs4/common/drbg"
-	"github.com/OperatorFoundation/obfs4/common/ntor"
-	"github.com/OperatorFoundation/obfs4/common/probdist"
-	"github.com/OperatorFoundation/obfs4/common/replayfilter"
-	"github.com/OperatorFoundation/obfs4/transports/base"
-	"github.com/OperatorFoundation/obfs4/transports/obfs4/framing"
-)
-
-const (
-	transportName = "obfs4"
-
-	nodeIDArg     = "node-id"
-	publicKeyArg  = "public-key"
-	privateKeyArg = "private-key"
-	seedArg       = "drbg-seed"
-	iatArg        = "iat-mode"
-	certArg       = "cert"
-
-	biasCmdArg = "obfs4-distBias"
-
-	seedLength             = drbg.SeedLength
-	headerLength           = framing.FrameOverhead + packetOverhead
-	clientHandshakeTimeout = time.Duration(60) * time.Second
-	serverHandshakeTimeout = time.Duration(30) * time.Second
-	replayTTL              = time.Duration(3) * time.Hour
-
-	maxIATDelay        = 100
-	maxCloseDelayBytes = maxHandshakeLength
-	maxCloseDelay      = 60
-)
-
-const (
-	iatNone = iota
-	iatEnabled
-	iatParanoid
-)
-
-// biasedDist controls if the probability table will be ScrambleSuit style or
-// uniformly distributed.
-var biasedDist bool
-
-type obfs4ClientArgs struct {
-	nodeID     *ntor.NodeID
-	publicKey  *ntor.PublicKey
-	sessionKey *ntor.Keypair
-	iatMode    int
-}
-
-// Transport is the obfs4 implementation of the base.Transport interface.
-type Transport struct{}
-
-// Name returns the name of the obfs4 transport protocol.
-func (t *Transport) Name() string {
-	return transportName
-}
-
-// ClientFactory returns a new obfs4ClientFactory instance.
-func (t *Transport) ClientFactory(stateDir string) (base.ClientFactory, error) {
-	cf := &obfs4ClientFactory{transport: t}
-	return cf, nil
-}
-
-// ServerFactory returns a new obfs4ServerFactory instance.
-func (t *Transport) ServerFactory(stateDir string, args *pt.Args) (base.ServerFactory, error) {
-	st, err := serverStateFromArgs(stateDir, args)
-	if err != nil {
-		return nil, err
-	}
-
-	var iatSeed *drbg.Seed
-	if st.iatMode != iatNone {
-		iatSeedSrc := sha256.Sum256(st.drbgSeed.Bytes()[:])
-		var err error
-		iatSeed, err = drbg.SeedFromBytes(iatSeedSrc[:])
-		if err != nil {
-			return nil, err
-		}
-	}
-
-	// Store the arguments that should appear in our descriptor for the clients.
-	ptArgs := pt.Args{}
-	ptArgs.Add(certArg, st.cert.String())
-	ptArgs.Add(iatArg, strconv.Itoa(st.iatMode))
-
-	// Initialize the replay filter.
-	filter, err := replayfilter.New(replayTTL)
-	if err != nil {
-		return nil, err
-	}
-
-	// Initialize the close thresholds for failed connections.
-	drbg, err := drbg.NewHashDrbg(st.drbgSeed)
-	if err != nil {
-		return nil, err
-	}
-	rng := rand.New(drbg)
-
-	sf := &obfs4ServerFactory{t, &ptArgs, st.nodeID, st.identityKey, st.drbgSeed, iatSeed, st.iatMode, filter, rng.Intn(maxCloseDelayBytes), rng.Intn(maxCloseDelay)}
-	return sf, nil
-}
-
-type obfs4ClientFactory struct {
-	transport base.Transport
-}
-
-func (cf *obfs4ClientFactory) Transport() base.Transport {
-	return cf.transport
-}
-
-func (cf *obfs4ClientFactory) ParseArgs(args *pt.Args) (interface{}, error) {
-	var nodeID *ntor.NodeID
-	var publicKey *ntor.PublicKey
-
-	// The "new" (version >= 0.0.3) bridge lines use a unified "cert" argument
-	// for the Node ID and Public Key.
-	certStr, ok := args.Get(certArg)
-	if ok {
-		cert, err := serverCertFromString(certStr)
-		if err != nil {
-			return nil, err
-		}
-		nodeID, publicKey = cert.unpack()
-	} else {
-		// The "old" style (version <= 0.0.2) bridge lines use separate Node ID
-		// and Public Key arguments in Base16 encoding and are a UX disaster.
-		nodeIDStr, ok := args.Get(nodeIDArg)
-		if !ok {
-			return nil, fmt.Errorf("missing argument '%s'", nodeIDArg)
-		}
-		var err error
-		if nodeID, err = ntor.NodeIDFromHex(nodeIDStr); err != nil {
-			return nil, err
-		}
-
-		publicKeyStr, ok := args.Get(publicKeyArg)
-		if !ok {
-			return nil, fmt.Errorf("missing argument '%s'", publicKeyArg)
-		}
-		if publicKey, err = ntor.PublicKeyFromHex(publicKeyStr); err != nil {
-			return nil, err
-		}
-	}
-
-	// IAT config is common across the two bridge line formats.
-	iatStr, ok := args.Get(iatArg)
-	if !ok {
-		return nil, fmt.Errorf("missing argument '%s'", iatArg)
-	}
-	iatMode, err := strconv.Atoi(iatStr)
-	if err != nil || iatMode < iatNone || iatMode > iatParanoid {
-		return nil, fmt.Errorf("invalid iat-mode '%d'", iatMode)
-	}
-
-	// Generate the session key pair before connectiong to hide the Elligator2
-	// rejection sampling from network observers.
-	sessionKey, err := ntor.NewKeypair(true)
-	if err != nil {
-		return nil, err
-	}
-
-	return &obfs4ClientArgs{nodeID, publicKey, sessionKey, iatMode}, nil
-}
-
-func (cf *obfs4ClientFactory) Dial(network, addr string, dialFn base.DialFunc, args interface{}) (net.Conn, error) {
-	// Validate args before bothering to open connection.
-	ca, ok := args.(*obfs4ClientArgs)
-	if !ok {
-		return nil, fmt.Errorf("invalid argument type for args")
-	}
-	conn, err := dialFn(network, addr)
-	if err != nil {
-		return nil, err
-	}
-	dialConn := conn
-	if conn, err = newObfs4ClientConn(conn, ca); err != nil {
-		dialConn.Close()
-		return nil, err
-	}
-	return conn, nil
-}
-
-type obfs4ServerFactory struct {
-	transport base.Transport
-	args      *pt.Args
-
-	nodeID       *ntor.NodeID
-	identityKey  *ntor.Keypair
-	lenSeed      *drbg.Seed
-	iatSeed      *drbg.Seed
-	iatMode      int
-	replayFilter *replayfilter.ReplayFilter
-
-	closeDelayBytes int
-	closeDelay      int
-}
-
-func (sf *obfs4ServerFactory) Transport() base.Transport {
-	return sf.transport
-}
-
-func (sf *obfs4ServerFactory) Args() *pt.Args {
-	return sf.args
-}
-
-func (sf *obfs4ServerFactory) WrapConn(conn net.Conn) (net.Conn, error) {
-	// Not much point in having a separate newObfs4ServerConn routine when
-	// wrapping requires using values from the factory instance.
-
-	// Generate the session keypair *before* consuming data from the peer, to
-	// attempt to mask the rejection sampling due to use of Elligator2.  This
-	// might be futile, but the timing differential isn't very large on modern
-	// hardware, and there are far easier statistical attacks that can be
-	// mounted as a distinguisher.
-	sessionKey, err := ntor.NewKeypair(true)
-	if err != nil {
-		return nil, err
-	}
-
-	lenDist := probdist.New(sf.lenSeed, 0, framing.MaximumSegmentLength, biasedDist)
-	var iatDist *probdist.WeightedDist
-	if sf.iatSeed != nil {
-		iatDist = probdist.New(sf.iatSeed, 0, maxIATDelay, biasedDist)
-	}
-
-	c := &obfs4Conn{conn, true, lenDist, iatDist, sf.iatMode, bytes.NewBuffer(nil), bytes.NewBuffer(nil), nil, nil}
-
-	startTime := time.Now()
-
-	if err = c.serverHandshake(sf, sessionKey); err != nil {
-		c.closeAfterDelay(sf, startTime)
-		return nil, err
-	}
-
-	return c, nil
-}
-
-type obfs4Conn struct {
-	net.Conn
-
-	isServer bool
-
-	lenDist *probdist.WeightedDist
-	iatDist *probdist.WeightedDist
-	iatMode int
-
-	receiveBuffer        *bytes.Buffer
-	receiveDecodedBuffer *bytes.Buffer
-
-	encoder *framing.Encoder
-	decoder *framing.Decoder
-}
-
-func newObfs4ClientConn(conn net.Conn, args *obfs4ClientArgs) (c *obfs4Conn, err error) {
-	// Generate the initial protocol polymorphism distribution(s).
-	var seed *drbg.Seed
-	if seed, err = drbg.NewSeed(); err != nil {
-		return
-	}
-	lenDist := probdist.New(seed, 0, framing.MaximumSegmentLength, biasedDist)
-	var iatDist *probdist.WeightedDist
-	if args.iatMode != iatNone {
-		var iatSeed *drbg.Seed
-		iatSeedSrc := sha256.Sum256(seed.Bytes()[:])
-		if iatSeed, err = drbg.SeedFromBytes(iatSeedSrc[:]); err != nil {
-			return
-		}
-		iatDist = probdist.New(iatSeed, 0, maxIATDelay, biasedDist)
-	}
-
-	// Allocate the client structure.
-	c = &obfs4Conn{conn, false, lenDist, iatDist, args.iatMode, bytes.NewBuffer(nil), bytes.NewBuffer(nil), nil, nil}
-
-	// Start the handshake timeout.
-	deadline := time.Now().Add(clientHandshakeTimeout)
-	if err = conn.SetDeadline(deadline); err != nil {
-		return nil, err
-	}
-
-	if err = c.clientHandshake(args.nodeID, args.publicKey, args.sessionKey); err != nil {
-		return nil, err
-	}
-
-	// Stop the handshake timeout.
-	if err = conn.SetDeadline(time.Time{}); err != nil {
-		return nil, err
-	}
-
-	return
-}
-
-func (conn *obfs4Conn) clientHandshake(nodeID *ntor.NodeID, peerIdentityKey *ntor.PublicKey, sessionKey *ntor.Keypair) error {
-	if conn.isServer {
-		return fmt.Errorf("clientHandshake called on server connection")
-	}
-
-	// Generate and send the client handshake.
-	hs := newClientHandshake(nodeID, peerIdentityKey, sessionKey)
-	blob, err := hs.generateHandshake()
-	if err != nil {
-		return err
-	}
-	if _, err = conn.Conn.Write(blob); err != nil {
-		return err
-	}
-
-	// Consume the server handshake.
-	var hsBuf [maxHandshakeLength]byte
-	for {
-		n, err := conn.Conn.Read(hsBuf[:])
-		if err != nil {
-			// The Read() could have returned data and an error, but there is
-			// no point in continuing on an EOF or whatever.
-			return err
-		}
-		conn.receiveBuffer.Write(hsBuf[:n])
-
-		n, seed, err := hs.parseServerHandshake(conn.receiveBuffer.Bytes())
-		if err == ErrMarkNotFoundYet {
-			continue
-		} else if err != nil {
-			return err
-		}
-		_ = conn.receiveBuffer.Next(n)
-
-		// Use the derived key material to intialize the link crypto.
-		okm := ntor.Kdf(seed, framing.KeyLength*2)
-		conn.encoder = framing.NewEncoder(okm[:framing.KeyLength])
-		conn.decoder = framing.NewDecoder(okm[framing.KeyLength:])
-
-		return nil
-	}
-}
-
-func (conn *obfs4Conn) serverHandshake(sf *obfs4ServerFactory, sessionKey *ntor.Keypair) error {
-	if !conn.isServer {
-		return fmt.Errorf("serverHandshake called on client connection")
-	}
-
-	// Generate the server handshake, and arm the base timeout.
-	hs := newServerHandshake(sf.nodeID, sf.identityKey, sessionKey)
-	if err := conn.Conn.SetDeadline(time.Now().Add(serverHandshakeTimeout)); err != nil {
-		return err
-	}
-
-	// Consume the client handshake.
-	var hsBuf [maxHandshakeLength]byte
-	for {
-		n, err := conn.Conn.Read(hsBuf[:])
-		if err != nil {
-			// The Read() could have returned data and an error, but there is
-			// no point in continuing on an EOF or whatever.
-			return err
-		}
-		conn.receiveBuffer.Write(hsBuf[:n])
-
-		seed, err := hs.parseClientHandshake(sf.replayFilter, conn.receiveBuffer.Bytes())
-		if err == ErrMarkNotFoundYet {
-			continue
-		} else if err != nil {
-			return err
-		}
-		conn.receiveBuffer.Reset()
-
-		if err := conn.Conn.SetDeadline(time.Time{}); err != nil {
-			return nil
-		}
-
-		// Use the derived key material to intialize the link crypto.
-		okm := ntor.Kdf(seed, framing.KeyLength*2)
-		conn.encoder = framing.NewEncoder(okm[framing.KeyLength:])
-		conn.decoder = framing.NewDecoder(okm[:framing.KeyLength])
-
-		break
-	}
-
-	// Since the current and only implementation always sends a PRNG seed for
-	// the length obfuscation, this makes the amount of data received from the
-	// server inconsistent with the length sent from the client.
-	//
-	// Rebalance this by tweaking the client mimimum padding/server maximum
-	// padding, and sending the PRNG seed unpadded (As in, treat the PRNG seed
-	// as part of the server response).  See inlineSeedFrameLength in
-	// handshake_ntor.go.
-
-	// Generate/send the response.
-	blob, err := hs.generateHandshake()
-	if err != nil {
-		return err
-	}
-	var frameBuf bytes.Buffer
-	if _, err = frameBuf.Write(blob); err != nil {
-		return err
-	}
-
-	// Send the PRNG seed as the first packet.
-	if err := conn.makePacket(&frameBuf, packetTypePrngSeed, sf.lenSeed.Bytes()[:], 0); err != nil {
-		return err
-	}
-	if _, err = conn.Conn.Write(frameBuf.Bytes()); err != nil {
-		return err
-	}
-
-	return nil
-}
-
-func (conn *obfs4Conn) Read(b []byte) (n int, err error) {
-	// If there is no payload from the previous Read() calls, consume data off
-	// the network.  Not all data received is guaranteed to be usable payload,
-	// so do this in a loop till data is present or an error occurs.
-	for conn.receiveDecodedBuffer.Len() == 0 {
-		err = conn.readPackets()
-		if err == framing.ErrAgain {
-			// Don't proagate this back up the call stack if we happen to break
-			// out of the loop.
-			err = nil
-			continue
-		} else if err != nil {
-			break
-		}
-	}
-
-	// Even if err is set, attempt to do the read anyway so that all decoded
-	// data gets relayed before the connection is torn down.
-	if conn.receiveDecodedBuffer.Len() > 0 {
-		var berr error
-		n, berr = conn.receiveDecodedBuffer.Read(b)
-		if err == nil {
-			// Only propagate berr if there are not more important (fatal)
-			// errors from the network/crypto/packet processing.
-			err = berr
-		}
-	}
-
-	return
-}
-
-func (conn *obfs4Conn) Write(b []byte) (n int, err error) {
-	chopBuf := bytes.NewBuffer(b)
-	var payload [maxPacketPayloadLength]byte
-	var frameBuf bytes.Buffer
-
-	// Chop the pending data into payload frames.
-	for chopBuf.Len() > 0 {
-		// Send maximum sized frames.
-		rdLen := 0
-		rdLen, err = chopBuf.Read(payload[:])
-		if err != nil {
-			return 0, err
-		} else if rdLen == 0 {
-			panic(fmt.Sprintf("BUG: Write(), chopping length was 0"))
-		}
-		n += rdLen
-
-		err = conn.makePacket(&frameBuf, packetTypePayload, payload[:rdLen], 0)
-		if err != nil {
-			return 0, err
-		}
-	}
-
-	if conn.iatMode != iatParanoid {
-		// For non-paranoid IAT, pad once per burst.  Paranoid IAT handles
-		// things differently.
-		if err = conn.padBurst(&frameBuf, conn.lenDist.Sample()); err != nil {
-			return 0, err
-		}
-	}
-
-	// Write the pending data onto the network.  Partial writes are fatal,
-	// because the frame encoder state is advanced, and the code doesn't keep
-	// frameBuf around.  In theory, write timeouts and whatnot could be
-	// supported if this wasn't the case, but that complicates the code.
-	if conn.iatMode != iatNone {
-		var iatFrame [framing.MaximumSegmentLength]byte
-		for frameBuf.Len() > 0 {
-			iatWrLen := 0
-
-			switch conn.iatMode {
-			case iatEnabled:
-				// Standard (ScrambleSuit-style) IAT obfuscation optimizes for
-				// bulk transport and will write ~MTU sized frames when
-				// possible.
-				iatWrLen, err = frameBuf.Read(iatFrame[:])
-
-			case iatParanoid:
-				// Paranoid IAT obfuscation throws performance out of the
-				// window and will sample the length distribution every time a
-				// write is scheduled.
-				targetLen := conn.lenDist.Sample()
-				if frameBuf.Len() < targetLen {
-					// There's not enough data buffered for the target write,
-					// so padding must be inserted.
-					if err = conn.padBurst(&frameBuf, targetLen); err != nil {
-						return 0, err
-					}
-					if frameBuf.Len() != targetLen {
-						// Ugh, padding came out to a value that required more
-						// than one frame, this is relatively unlikely so just
-						// resample since there's enough data to ensure that
-						// the next sample will be written.
-						continue
-					}
-				}
-				iatWrLen, err = frameBuf.Read(iatFrame[:targetLen])
-			}
-			if err != nil {
-				return 0, err
-			} else if iatWrLen == 0 {
-				panic(fmt.Sprintf("BUG: Write(), iat length was 0"))
-			}
-
-			// Calculate the delay.  The delay resolution is 100 usec, leading
-			// to a maximum delay of 10 msec.
-			iatDelta := time.Duration(conn.iatDist.Sample() * 100)
-
-			// Write then sleep.
-			_, err = conn.Conn.Write(iatFrame[:iatWrLen])
-			if err != nil {
-				return 0, err
-			}
-			time.Sleep(iatDelta * time.Microsecond)
-		}
-	} else {
-		_, err = conn.Conn.Write(frameBuf.Bytes())
-	}
-
-	return
-}
-
-func (conn *obfs4Conn) SetDeadline(t time.Time) error {
-	return syscall.ENOTSUP
-}
-
-func (conn *obfs4Conn) SetWriteDeadline(t time.Time) error {
-	return syscall.ENOTSUP
-}
-
-func (conn *obfs4Conn) closeAfterDelay(sf *obfs4ServerFactory, startTime time.Time) {
-	// I-it's not like I w-wanna handshake with you or anything.  B-b-baka!
-	defer conn.Conn.Close()
-
-	delay := time.Duration(sf.closeDelay)*time.Second + serverHandshakeTimeout
-	deadline := startTime.Add(delay)
-	if time.Now().After(deadline) {
-		return
-	}
-
-	if err := conn.Conn.SetReadDeadline(deadline); err != nil {
-		return
-	}
-
-	// Consume and discard data on this connection until either the specified
-	// interval passes or a certain size has been reached.
-	discarded := 0
-	var buf [framing.MaximumSegmentLength]byte
-	for discarded < int(sf.closeDelayBytes) {
-		n, err := conn.Conn.Read(buf[:])
-		if err != nil {
-			return
-		}
-		discarded += n
-	}
-}
-
-func (conn *obfs4Conn) padBurst(burst *bytes.Buffer, toPadTo int) (err error) {
-	tailLen := burst.Len() % framing.MaximumSegmentLength
-
-	padLen := 0
-	if toPadTo >= tailLen {
-		padLen = toPadTo - tailLen
-	} else {
-		padLen = (framing.MaximumSegmentLength - tailLen) + toPadTo
-	}
-
-	if padLen > headerLength {
-		err = conn.makePacket(burst, packetTypePayload, []byte{},
-			uint16(padLen-headerLength))
-		if err != nil {
-			return
-		}
-	} else if padLen > 0 {
-		err = conn.makePacket(burst, packetTypePayload, []byte{},
-			maxPacketPayloadLength)
-		if err != nil {
-			return
-		}
-		err = conn.makePacket(burst, packetTypePayload, []byte{},
-			uint16(padLen))
-		if err != nil {
-			return
-		}
-	}
-
-	return
-}
-
-func init() {
-	flag.BoolVar(&biasedDist, biasCmdArg, false, "Enable obfs4 using ScrambleSuit style table generation")
-}
-
-var _ base.ClientFactory = (*obfs4ClientFactory)(nil)
-var _ base.ServerFactory = (*obfs4ServerFactory)(nil)
-var _ base.Transport = (*Transport)(nil)
-var _ net.Conn = (*obfs4Conn)(nil)
diff --git a/transports/obfs4/packet.go b/transports/obfs4/packet.go
deleted file mode 100644
index ac3028a..0000000
--- a/transports/obfs4/packet.go
+++ /dev/null
@@ -1,176 +0,0 @@
-/*
- * Copyright (c) 2014, Yawning Angel <yawning at torproject dot org>
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are met:
- *
- *  * Redistributions of source code must retain the above copyright notice,
- *    this list of conditions and the following disclaimer.
- *
- *  * Redistributions in binary form must reproduce the above copyright notice,
- *    this list of conditions and the following disclaimer in the documentation
- *    and/or other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
- * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
- * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
- * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
- * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
- * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
- * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
- * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
- * POSSIBILITY OF SUCH DAMAGE.
- */
-
-package obfs4
-
-import (
-	"crypto/sha256"
-	"encoding/binary"
-	"fmt"
-	"io"
-
-	"github.com/OperatorFoundation/obfs4/common/drbg"
-	"github.com/OperatorFoundation/obfs4/transports/obfs4/framing"
-)
-
-const (
-	packetOverhead          = 2 + 1
-	maxPacketPayloadLength  = framing.MaximumFramePayloadLength - packetOverhead
-	maxPacketPaddingLength  = maxPacketPayloadLength
-	seedPacketPayloadLength = seedLength
-
-	consumeReadSize = framing.MaximumSegmentLength * 16
-)
-
-const (
-	packetTypePayload = iota
-	packetTypePrngSeed
-)
-
-// InvalidPacketLengthError is the error returned when decodePacket detects a
-// invalid packet length/
-type InvalidPacketLengthError int
-
-func (e InvalidPacketLengthError) Error() string {
-	return fmt.Sprintf("packet: Invalid packet length: %d", int(e))
-}
-
-// InvalidPayloadLengthError is the error returned when decodePacket rejects the
-// payload length.
-type InvalidPayloadLengthError int
-
-func (e InvalidPayloadLengthError) Error() string {
-	return fmt.Sprintf("packet: Invalid payload length: %d", int(e))
-}
-
-var zeroPadBytes [maxPacketPaddingLength]byte
-
-func (conn *obfs4Conn) makePacket(w io.Writer, pktType uint8, data []byte, padLen uint16) error {
-	var pkt [framing.MaximumFramePayloadLength]byte
-
-	if len(data)+int(padLen) > maxPacketPayloadLength {
-		panic(fmt.Sprintf("BUG: makePacket() len(data) + padLen > maxPacketPayloadLength: %d + %d > %d",
-			len(data), padLen, maxPacketPayloadLength))
-	}
-
-	// Packets are:
-	//   uint8_t type      packetTypePayload (0x00)
-	//   uint16_t length   Length of the payload (Big Endian).
-	//   uint8_t[] payload Data payload.
-	//   uint8_t[] padding Padding.
-	pkt[0] = pktType
-	binary.BigEndian.PutUint16(pkt[1:], uint16(len(data)))
-	if len(data) > 0 {
-		copy(pkt[3:], data[:])
-	}
-	copy(pkt[3+len(data):], zeroPadBytes[:padLen])
-
-	pktLen := packetOverhead + len(data) + int(padLen)
-
-	// Encode the packet in an AEAD frame.
-	var frame [framing.MaximumSegmentLength]byte
-	frameLen, err := conn.encoder.Encode(frame[:], pkt[:pktLen])
-	if err != nil {
-		// All encoder errors are fatal.
-		return err
-	}
-	wrLen, err := w.Write(frame[:frameLen])
-	if err != nil {
-		return err
-	} else if wrLen < frameLen {
-		return io.ErrShortWrite
-	}
-
-	return nil
-}
-
-func (conn *obfs4Conn) readPackets() (err error) {
-	// Attempt to read off the network.
-	var buf [consumeReadSize]byte
-	rdLen, rdErr := conn.Conn.Read(buf[:])
-	conn.receiveBuffer.Write(buf[:rdLen])
-
-	var decoded [framing.MaximumFramePayloadLength]byte
-	for conn.receiveBuffer.Len() > 0 {
-		// Decrypt an AEAD frame.
-		decLen := 0
-		decLen, err = conn.decoder.Decode(decoded[:], conn.receiveBuffer)
-		if err == framing.ErrAgain {
-			break
-		} else if err != nil {
-			break
-		} else if decLen < packetOverhead {
-			err = InvalidPacketLengthError(decLen)
-			break
-		}
-
-		// Decode the packet.
-		pkt := decoded[0:decLen]
-		pktType := pkt[0]
-		payloadLen := binary.BigEndian.Uint16(pkt[1:])
-		if int(payloadLen) > len(pkt)-packetOverhead {
-			err = InvalidPayloadLengthError(int(payloadLen))
-			break
-		}
-		payload := pkt[3 : 3+payloadLen]
-
-		switch pktType {
-		case packetTypePayload:
-			if payloadLen > 0 {
-				conn.receiveDecodedBuffer.Write(payload)
-			}
-		case packetTypePrngSeed:
-			// Only regenerate the distribution if we are the client.
-			if len(payload) == seedPacketPayloadLength && !conn.isServer {
-				var seed *drbg.Seed
-				seed, err = drbg.SeedFromBytes(payload)
-				if err != nil {
-					break
-				}
-				conn.lenDist.Reset(seed)
-				if conn.iatDist != nil {
-					iatSeedSrc := sha256.Sum256(seed.Bytes()[:])
-					iatSeed, err := drbg.SeedFromBytes(iatSeedSrc[:])
-					if err != nil {
-						break
-					}
-					conn.iatDist.Reset(iatSeed)
-				}
-			}
-		default:
-			// Ignore unknown packet types.
-		}
-	}
-
-	// Read errors (all fatal) take priority over various frame processing
-	// errors.
-	if rdErr != nil {
-		return rdErr
-	}
-
-	return
-}
diff --git a/transports/obfs4/statefile.go b/transports/obfs4/statefile.go
deleted file mode 100644
index 6f89c6c..0000000
--- a/transports/obfs4/statefile.go
+++ /dev/null
@@ -1,252 +0,0 @@
-/*
- * Copyright (c) 2014, Yawning Angel <yawning at torproject dot org>
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are met:
- *
- *  * Redistributions of source code must retain the above copyright notice,
- *    this list of conditions and the following disclaimer.
- *
- *  * Redistributions in binary form must reproduce the above copyright notice,
- *    this list of conditions and the following disclaimer in the documentation
- *    and/or other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
- * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
- * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
- * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
- * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
- * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
- * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
- * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
- * POSSIBILITY OF SUCH DAMAGE.
- */
-
-package obfs4
-
-import (
-	"encoding/base64"
-	"encoding/json"
-	"fmt"
-	"io/ioutil"
-	"os"
-	"path"
-	"strconv"
-	"strings"
-
-	"git.torproject.org/pluggable-transports/goptlib.git"
-	"github.com/OperatorFoundation/obfs4/common/csrand"
-	"github.com/OperatorFoundation/obfs4/common/drbg"
-	"github.com/OperatorFoundation/obfs4/common/ntor"
-)
-
-const (
-	stateFile  = "obfs4_state.json"
-	bridgeFile = "obfs4_bridgeline.txt"
-
-	certSuffix = "=="
-	certLength = ntor.NodeIDLength + ntor.PublicKeyLength
-)
-
-type jsonServerState struct {
-	NodeID     string `json:"node-id"`
-	PrivateKey string `json:"private-key"`
-	PublicKey  string `json:"public-key"`
-	DrbgSeed   string `json:"drbg-seed"`
-	IATMode    int    `json:"iat-mode"`
-}
-
-type obfs4ServerCert struct {
-	raw []byte
-}
-
-func (cert *obfs4ServerCert) String() string {
-	return strings.TrimSuffix(base64.StdEncoding.EncodeToString(cert.raw), certSuffix)
-}
-
-func (cert *obfs4ServerCert) unpack() (*ntor.NodeID, *ntor.PublicKey) {
-	if len(cert.raw) != certLength {
-		panic(fmt.Sprintf("cert length %d is invalid", len(cert.raw)))
-	}
-
-	nodeID, _ := ntor.NewNodeID(cert.raw[:ntor.NodeIDLength])
-	pubKey, _ := ntor.NewPublicKey(cert.raw[ntor.NodeIDLength:])
-
-	return nodeID, pubKey
-}
-
-func serverCertFromString(encoded string) (*obfs4ServerCert, error) {
-	decoded, err := base64.StdEncoding.DecodeString(encoded + certSuffix)
-	if err != nil {
-		return nil, fmt.Errorf("failed to decode cert: %s", err)
-	}
-
-	if len(decoded) != certLength {
-		return nil, fmt.Errorf("cert length %d is invalid", len(decoded))
-	}
-
-	return &obfs4ServerCert{raw: decoded}, nil
-}
-
-func serverCertFromState(st *obfs4ServerState) *obfs4ServerCert {
-	cert := new(obfs4ServerCert)
-	cert.raw = append(st.nodeID.Bytes()[:], st.identityKey.Public().Bytes()[:]...)
-	return cert
-}
-
-type obfs4ServerState struct {
-	nodeID      *ntor.NodeID
-	identityKey *ntor.Keypair
-	drbgSeed    *drbg.Seed
-	iatMode     int
-
-	cert *obfs4ServerCert
-}
-
-func (st *obfs4ServerState) clientString() string {
-	return fmt.Sprintf("%s=%s %s=%d", certArg, st.cert, iatArg, st.iatMode)
-}
-
-func serverStateFromArgs(stateDir string, args *pt.Args) (*obfs4ServerState, error) {
-	var js jsonServerState
-	var nodeIDOk, privKeyOk, seedOk bool
-
-	js.NodeID, nodeIDOk = args.Get(nodeIDArg)
-	js.PrivateKey, privKeyOk = args.Get(privateKeyArg)
-	js.DrbgSeed, seedOk = args.Get(seedArg)
-	iatStr, iatOk := args.Get(iatArg)
-
-	if !privKeyOk && !nodeIDOk && !seedOk && !iatOk {
-		if err := jsonServerStateFromFile(stateDir, &js); err != nil {
-			return nil, err
-		}
-	} else if !privKeyOk {
-		return nil, fmt.Errorf("missing argument '%s'", privateKeyArg)
-	} else if !nodeIDOk {
-		return nil, fmt.Errorf("missing argument '%s'", nodeIDArg)
-	} else if !seedOk {
-		return nil, fmt.Errorf("missing argument '%s'", seedArg)
-	} else if !iatOk {
-		// Disable IAT if not specified.
-		return nil, fmt.Errorf("missing argument '%s'", iatArg)
-	} else {
-		// Parse and validate the iat-mode argument.
-		iatMode, err := strconv.Atoi(iatStr)
-		if err != nil {
-			return nil, fmt.Errorf("malformed iat-mode '%s'", iatStr)
-		}
-		js.IATMode = iatMode
-	}
-
-	return serverStateFromJSONServerState(stateDir, &js)
-}
-
-func serverStateFromJSONServerState(stateDir string, js *jsonServerState) (*obfs4ServerState, error) {
-	var err error
-
-	st := new(obfs4ServerState)
-	if st.nodeID, err = ntor.NodeIDFromHex(js.NodeID); err != nil {
-		return nil, err
-	}
-	if st.identityKey, err = ntor.KeypairFromHex(js.PrivateKey); err != nil {
-		return nil, err
-	}
-	if st.drbgSeed, err = drbg.SeedFromHex(js.DrbgSeed); err != nil {
-		return nil, err
-	}
-	if js.IATMode < iatNone || js.IATMode > iatParanoid {
-		return nil, fmt.Errorf("invalid iat-mode '%d'", js.IATMode)
-	}
-	st.iatMode = js.IATMode
-	st.cert = serverCertFromState(st)
-
-	// Generate a human readable summary of the configured endpoint.
-	if err = newBridgeFile(stateDir, st); err != nil {
-		return nil, err
-	}
-
-	return st, nil
-}
-
-func jsonServerStateFromFile(stateDir string, js *jsonServerState) error {
-	fPath := path.Join(stateDir, stateFile)
-	f, err := ioutil.ReadFile(fPath)
-	if err != nil {
-		if os.IsNotExist(err) {
-			if err = newJSONServerState(stateDir, js); err == nil {
-				return nil
-			}
-		}
-		return err
-	}
-
-	if err := json.Unmarshal(f, js); err != nil {
-		return fmt.Errorf("failed to load statefile '%s': %s", fPath, err)
-	}
-
-	return nil
-}
-
-func newJSONServerState(stateDir string, js *jsonServerState) (err error) {
-	// Generate everything a server needs, using the cryptographic PRNG.
-	var st obfs4ServerState
-	rawID := make([]byte, ntor.NodeIDLength)
-	if err = csrand.Bytes(rawID); err != nil {
-		return
-	}
-	if st.nodeID, err = ntor.NewNodeID(rawID); err != nil {
-		return
-	}
-	if st.identityKey, err = ntor.NewKeypair(false); err != nil {
-		return
-	}
-	if st.drbgSeed, err = drbg.NewSeed(); err != nil {
-		return
-	}
-	st.iatMode = iatNone
-
-	// Encode it into JSON format and write the state file.
-	js.NodeID = st.nodeID.Hex()
-	js.PrivateKey = st.identityKey.Private().Hex()
-	js.PublicKey = st.identityKey.Public().Hex()
-	js.DrbgSeed = st.drbgSeed.Hex()
-	js.IATMode = st.iatMode
-
-	var encoded []byte
-	if encoded, err = json.Marshal(js); err != nil {
-		return
-	}
-
-	if err = ioutil.WriteFile(path.Join(stateDir, stateFile), encoded, 0600); err != nil {
-		return err
-	}
-
-	return nil
-}
-
-func newBridgeFile(stateDir string, st *obfs4ServerState) error {
-	const prefix = "# obfs4 torrc client bridge line\n" +
-		"#\n" +
-		"# This file is an automatically generated bridge line based on\n" +
-		"# the current obfs4proxy configuration.  EDITING IT WILL HAVE\n" +
-		"# NO EFFECT.\n" +
-		"#\n" +
-		"# Before distributing this Bridge, edit the placeholder fields\n" +
-		"# to contain the actual values:\n" +
-		"#  <IP ADDRESS>  - The public IP address of your obfs4 bridge.\n" +
-		"#  <PORT>        - The TCP/IP port of your obfs4 bridge.\n" +
-		"#  <FINGERPRINT> - The bridge's fingerprint.\n\n"
-
-	bridgeLine := fmt.Sprintf("Bridge obfs4 <IP ADDRESS>:<PORT> <FINGERPRINT> %s\n",
-		st.clientString())
-
-	tmp := []byte(prefix + bridgeLine)
-	if err := ioutil.WriteFile(path.Join(stateDir, bridgeFile), tmp, 0600); err != nil {
-		return err
-	}
-
-	return nil
-}