diff options
Diffstat (limited to 'obfs4.go')
| -rw-r--r-- | obfs4.go | 27 |
1 files changed, 15 insertions, 12 deletions
@@ -44,10 +44,8 @@ const ( headerLength = framing.FrameOverhead + packetOverhead connectionTimeout = time.Duration(30) * time.Second - minCloseThreshold = 0 - maxCloseThreshold = framing.MaximumSegmentLength * 5 - minCloseInterval = 0 - maxCloseInterval = 60 + maxCloseDelayBytes = framing.MaximumSegmentLength * 5 + maxCloseDelay = 60 ) type connState int @@ -77,6 +75,9 @@ type Obfs4Conn struct { // Server side state. listener *Obfs4Listener + startTime time.Time + closeDelayBytes int + closeDelay int } func (c *Obfs4Conn) padBurst(burst *bytes.Buffer) (err error) { @@ -116,11 +117,13 @@ func (c *Obfs4Conn) closeAfterDelay() { // I-it's not like I w-wanna handshake with you or anything. B-b-baka! defer c.conn.Close() - delaySecs := randRange(minCloseInterval, maxCloseInterval) - toDiscard := randRange(minCloseThreshold, maxCloseThreshold) + delay := time.Duration(c.closeDelay) * time.Second + deadline := c.startTime.Add(delay) + if time.Now().After(deadline) { + return + } - delay := time.Duration(delaySecs) * time.Second - err := c.conn.SetReadDeadline(time.Now().Add(delay)) + err := c.conn.SetReadDeadline(deadline) if err != nil { return } @@ -129,7 +132,7 @@ func (c *Obfs4Conn) closeAfterDelay() { // interval passes or a certain size has been reached. discarded := 0 var buf [framing.MaximumSegmentLength]byte - for discarded < int(toDiscard) { + for discarded < int(c.closeDelayBytes) { n, err := c.conn.Read(buf[:]) if err != nil { return @@ -324,9 +327,6 @@ func (c *Obfs4Conn) ServerHandshake() error { err := c.serverHandshake(c.listener.nodeID, c.listener.keyPair) c.listener = nil if err != nil { - // XXX: Maybe make the timeout period deterministic, since random - // hangup intervals are also suspicious. An ok value would be someting - // like the Nginx client_header_timeout (60s). c.closeAfterDelay() } @@ -544,6 +544,9 @@ func (l *Obfs4Listener) Accept() (net.Conn, error) { c.Close() return nil, err } + cObfs.startTime = time.Now() + cObfs.closeDelayBytes = cObfs.lenProbDist.rng.Intn(maxCloseDelayBytes) + cObfs.closeDelay = cObfs.lenProbDist.rng.Intn(maxCloseDelay) return cObfs, nil } |