2 GoVPN -- simple secure free software virtual private network daemon
3 Copyright (C) 2014-2016 Sergey Matveev <stargrave@stargrave.org>
5 This program is free software: you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by
7 the Free Software Foundation, either version 3 of the License, or
8 (at your option) any later version.
10 This program is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU General Public License for more details.
15 You should have received a copy of the GNU General Public License
16 along with this program. If not, see <http://www.gnu.org/licenses/>.
30 "golang.org/x/crypto/poly1305"
31 "golang.org/x/crypto/salsa20"
32 "golang.org/x/crypto/xtea"
38 TagSize = poly1305.TagSize
39 // S20BS is Salsa20's internal blocksize in bytes
41 // Maximal amount of bytes transfered with single key (4 GiB)
42 MaxBytesPerKey int64 = 1 << 32
43 // Heartbeat rate, relative to Timeout
45 // Minimal valid packet length
46 MinPktLength = 1 + 16 + 8
51 func newNonceCipher(key *[32]byte) *xtea.Cipher {
52 nonceKey := make([]byte, 16)
56 make([]byte, xtea.BlockSize),
59 ciph, err := xtea.NewCipher(nonceKey)
74 CPRCycle time.Duration `json:"-"`
78 // Cryptography related
79 Key *[SSize]byte `json:"-"`
80 NonceCipher *xtea.Cipher `json:"-"`
84 NonceExpect uint64 `json:"-"`
85 nonceBucket0 map[uint64]struct{}
86 nonceBucket1 map[uint64]struct{}
92 Timeout time.Duration `json:"-"`
96 willSentCycle time.Time
102 BytesPayloadOut int64
111 BusyR sync.Mutex `json:"-"`
114 keyAuthR *[SSize]byte
118 BusyT sync.Mutex `json:"-"`
121 keyAuthT *[SSize]byte
126 func (p *Peer) String() string {
127 return p.Id.String() + ":" + p.Addr
130 // Zero peer's memory state.
131 func (p *Peer) Zero() {
137 SliceZero(p.keyAuthR[:])
138 SliceZero(p.keyAuthT[:])
143 func (p *Peer) NonceExpectation(buf []byte) {
144 binary.BigEndian.PutUint64(buf, p.NonceExpect)
145 p.NonceCipher.Encrypt(buf, buf)
148 func newPeer(isClient bool, addr string, conn io.Writer, conf *PeerConf, key *[SSize]byte) *Peer {
150 timeout := conf.Timeout
152 cprCycle := cprCycleCalculate(conf.CPR)
153 noiseEnable := conf.Noise
158 timeout = timeout / TimeoutHeartbeat
161 bufSize := S20BS + 2*conf.MTU
163 bufSize += EncLessEnlargeSize
171 NoiseEnable: noiseEnable,
174 EncLess: conf.EncLess,
178 NonceCipher: newNonceCipher(key),
179 nonceBucket0: make(map[uint64]struct{}, NonceBucketSize),
180 nonceBucket1: make(map[uint64]struct{}, NonceBucketSize),
186 bufR: make([]byte, bufSize),
187 bufT: make([]byte, bufSize),
188 tagR: new([TagSize]byte),
189 tagT: new([TagSize]byte),
190 keyAuthR: new([SSize]byte),
191 keyAuthT: new([SSize]byte),
195 peer.NonceExpect = 0 + 2
198 peer.NonceExpect = 1 + 2
204 // Process incoming Ethernet packet.
205 // ready channel is TAPListen's synchronization channel used to tell him
206 // that he is free to receive new packets. Encrypted and authenticated
207 // packets will be sent to remote Peer side immediately.
208 func (p *Peer) EthProcess(data []byte) {
209 if len(data) > p.MTU-1 { // 1 is for padding byte
210 log.Println("Padded data packet size", len(data)+1, "is bigger than MTU", p.MTU, p)
216 // Zero size is a heartbeat packet
219 // If this heartbeat is necessary
220 if !p.LastSent.Add(p.Timeout).Before(p.now) {
224 p.bufT[S20BS+0] = PadByte
227 // Copy payload to our internal buffer and we are ready to
228 // accept the next one
229 copy(p.bufT[S20BS:], data)
230 p.bufT[S20BS+len(data)] = PadByte
231 p.BytesPayloadOut += int64(len(data))
234 if p.NoiseEnable && !p.EncLess {
235 p.frameT = p.bufT[S20BS : S20BS+p.MTU-TagSize]
236 } else if p.EncLess {
237 p.frameT = p.bufT[S20BS : S20BS+p.MTU]
239 p.frameT = p.bufT[S20BS : S20BS+len(data)+1+NonceSize]
242 binary.BigEndian.PutUint64(p.frameT[len(p.frameT)-NonceSize:], p.nonceOur)
243 p.NonceCipher.Encrypt(
244 p.frameT[len(p.frameT)-NonceSize:],
245 p.frameT[len(p.frameT)-NonceSize:],
250 out, err = EncLessEncode(
252 p.frameT[len(p.frameT)-NonceSize:],
253 p.frameT[:len(p.frameT)-NonceSize],
258 out = append(out, p.frameT[len(p.frameT)-NonceSize:]...)
260 salsa20.XORKeyStream(
261 p.bufT[:S20BS+len(p.frameT)-NonceSize],
262 p.bufT[:S20BS+len(p.frameT)-NonceSize],
263 p.frameT[len(p.frameT)-NonceSize:],
266 copy(p.keyAuthT[:], p.bufT[:SSize])
267 poly1305.Sum(p.tagT, p.frameT, p.keyAuthT)
268 atomic.AddInt64(&p.BytesOut, int64(len(p.frameT)+TagSize))
269 out = append(p.tagT[:], p.frameT...)
273 if p.CPRCycle != time.Duration(0) {
274 p.willSentCycle = p.LastSent.Add(p.CPRCycle)
275 if p.willSentCycle.After(p.now) {
276 time.Sleep(p.willSentCycle.Sub(p.now))
277 p.now = p.willSentCycle
286 func (p *Peer) PktProcess(data []byte, tap io.Writer, reorderable bool) bool {
287 if len(data) < MinPktLength {
294 out, err = EncLessDecode(
296 data[len(data)-NonceSize:],
297 data[:len(data)-NonceSize],
305 for i := 0; i < SSize; i++ {
308 copy(p.bufR[S20BS:], data[TagSize:])
309 salsa20.XORKeyStream(
310 p.bufR[:S20BS+len(data)-TagSize-NonceSize],
311 p.bufR[:S20BS+len(data)-TagSize-NonceSize],
312 data[len(data)-NonceSize:],
315 copy(p.keyAuthR[:], p.bufR[:SSize])
316 copy(p.tagR[:], data[:TagSize])
317 if !poly1305.Verify(p.tagR, data[TagSize:], p.keyAuthR) {
322 out = p.bufR[S20BS : S20BS+len(data)-TagSize-NonceSize]
325 // Check if received nonce is known to us in either of two buckets.
326 // If yes, then this is ignored duplicate.
327 // Check from the oldest bucket, as in most cases this will result
328 // in constant time check.
329 // If Bucket0 is filled, then it becomes Bucket1.
330 p.NonceCipher.Decrypt(
331 data[len(data)-NonceSize:],
332 data[len(data)-NonceSize:],
334 p.nonceRecv = binary.BigEndian.Uint64(data[len(data)-NonceSize:])
336 _, p.nonceFound0 = p.nonceBucket0[p.nonceRecv]
337 _, p.nonceFound1 = p.nonceBucket1[p.nonceRecv]
338 if p.nonceFound0 || p.nonceFound1 || p.nonceRecv+2*NonceBucketSize < p.nonceLatest {
343 p.nonceBucket0[p.nonceRecv] = struct{}{}
345 if p.nonceBucketN == NonceBucketSize {
346 p.nonceBucket1 = p.nonceBucket0
347 p.nonceBucket0 = make(map[uint64]struct{}, NonceBucketSize)
351 if p.nonceRecv != p.NonceExpect {
358 if p.nonceRecv > p.nonceLatest {
359 p.nonceLatest = p.nonceRecv
363 atomic.AddInt64(&p.BytesIn, int64(len(data)))
364 p.LastPing = time.Now()
365 p.pktSizeR = bytes.LastIndexByte(out, PadByte)
366 if p.pktSizeR == -1 {
371 for i := p.pktSizeR + 1; i < len(out); i++ {
383 p.BytesPayloadIn += int64(p.pktSizeR)
384 tap.Write(out[:p.pktSizeR])