1/*
2 *  Copyright 2004 The WebRTC Project Authors. All rights reserved.
3 *
4 *  Use of this source code is governed by a BSD-style license
5 *  that can be found in the LICENSE file in the root of the source
6 *  tree. An additional intellectual property rights grant can be found
7 *  in the file PATENTS.  All contributing project authors may
8 *  be found in the AUTHORS file in the root of the source tree.
9 */
10
11#ifndef WEBRTC_P2P_BASE_PSEUDOTCP_H_
12#define WEBRTC_P2P_BASE_PSEUDOTCP_H_
13
14#include <list>
15
16#include "webrtc/base/basictypes.h"
17#include "webrtc/base/stream.h"
18
19namespace cricket {
20
21//////////////////////////////////////////////////////////////////////
22// IPseudoTcpNotify
23//////////////////////////////////////////////////////////////////////
24
25class PseudoTcp;
26
27class IPseudoTcpNotify {
28 public:
29  // Notification of tcp events
30  virtual void OnTcpOpen(PseudoTcp* tcp) = 0;
31  virtual void OnTcpReadable(PseudoTcp* tcp) = 0;
32  virtual void OnTcpWriteable(PseudoTcp* tcp) = 0;
33  virtual void OnTcpClosed(PseudoTcp* tcp, uint32_t error) = 0;
34
35  // Write the packet onto the network
36  enum WriteResult { WR_SUCCESS, WR_TOO_LARGE, WR_FAIL };
37  virtual WriteResult TcpWritePacket(PseudoTcp* tcp,
38                                     const char* buffer, size_t len) = 0;
39
40 protected:
41  virtual ~IPseudoTcpNotify() {}
42};
43
44//////////////////////////////////////////////////////////////////////
45// PseudoTcp
46//////////////////////////////////////////////////////////////////////
47
48class PseudoTcp {
49 public:
50  static uint32_t Now();
51
52  PseudoTcp(IPseudoTcpNotify* notify, uint32_t conv);
53  virtual ~PseudoTcp();
54
55  int Connect();
56  int Recv(char* buffer, size_t len);
57  int Send(const char* buffer, size_t len);
58  void Close(bool force);
59  int GetError();
60
61  enum TcpState {
62    TCP_LISTEN, TCP_SYN_SENT, TCP_SYN_RECEIVED, TCP_ESTABLISHED, TCP_CLOSED
63  };
64  TcpState State() const { return m_state; }
65
66  // Call this when the PMTU changes.
67  void NotifyMTU(uint16_t mtu);
68
69  // Call this based on timeout value returned from GetNextClock.
70  // It's ok to call this too frequently.
71  void NotifyClock(uint32_t now);
72
73  // Call this whenever a packet arrives.
74  // Returns true if the packet was processed successfully.
75  bool NotifyPacket(const char * buffer, size_t len);
76
77  // Call this to determine the next time NotifyClock should be called.
78  // Returns false if the socket is ready to be destroyed.
79  bool GetNextClock(uint32_t now, long& timeout);
80
81  // Call these to get/set option values to tailor this PseudoTcp
82  // instance's behaviour for the kind of data it will carry.
83  // If an unrecognized option is set or got, an assertion will fire.
84  //
85  // Setting options for OPT_RCVBUF or OPT_SNDBUF after Connect() is called
86  // will result in an assertion.
87  enum Option {
88    OPT_NODELAY,      // Whether to enable Nagle's algorithm (0 == off)
89    OPT_ACKDELAY,     // The Delayed ACK timeout (0 == off).
90    OPT_RCVBUF,       // Set the receive buffer size, in bytes.
91    OPT_SNDBUF,       // Set the send buffer size, in bytes.
92  };
93  void GetOption(Option opt, int* value);
94  void SetOption(Option opt, int value);
95
96  // Returns current congestion window in bytes.
97  uint32_t GetCongestionWindow() const;
98
99  // Returns amount of data in bytes that has been sent, but haven't
100  // been acknowledged.
101  uint32_t GetBytesInFlight() const;
102
103  // Returns number of bytes that were written in buffer and haven't
104  // been sent.
105  uint32_t GetBytesBufferedNotSent() const;
106
107  // Returns current round-trip time estimate in milliseconds.
108  uint32_t GetRoundTripTimeEstimateMs() const;
109
110 protected:
111  enum SendFlags { sfNone, sfDelayedAck, sfImmediateAck };
112
113  struct Segment {
114    uint32_t conv, seq, ack;
115    uint8_t flags;
116    uint16_t wnd;
117    const char * data;
118    uint32_t len;
119    uint32_t tsval, tsecr;
120  };
121
122  struct SSegment {
123    SSegment(uint32_t s, uint32_t l, bool c)
124        : seq(s), len(l), /*tstamp(0),*/ xmit(0), bCtrl(c) {}
125    uint32_t seq, len;
126    // uint32_t tstamp;
127    uint8_t xmit;
128    bool bCtrl;
129  };
130  typedef std::list<SSegment> SList;
131
132  struct RSegment {
133    uint32_t seq, len;
134  };
135
136  uint32_t queue(const char* data, uint32_t len, bool bCtrl);
137
138  // Creates a packet and submits it to the network. This method can either
139  // send payload or just an ACK packet.
140  //
141  // |seq| is the sequence number of this packet.
142  // |flags| is the flags for sending this packet.
143  // |offset| is the offset to read from |m_sbuf|.
144  // |len| is the number of bytes to read from |m_sbuf| as payload. If this
145  // value is 0 then this is an ACK packet, otherwise this packet has payload.
146  IPseudoTcpNotify::WriteResult packet(uint32_t seq,
147                                       uint8_t flags,
148                                       uint32_t offset,
149                                       uint32_t len);
150  bool parse(const uint8_t* buffer, uint32_t size);
151
152  void attemptSend(SendFlags sflags = sfNone);
153
154  void closedown(uint32_t err = 0);
155
156  bool clock_check(uint32_t now, long& nTimeout);
157
158  bool process(Segment& seg);
159  bool transmit(const SList::iterator& seg, uint32_t now);
160
161  void adjustMTU();
162
163 protected:
164  // This method is used in test only to query receive buffer state.
165  bool isReceiveBufferFull() const;
166
167  // This method is only used in tests, to disable window scaling
168  // support for testing backward compatibility.
169  void disableWindowScale();
170
171 private:
172  // Queue the connect message with TCP options.
173  void queueConnectMessage();
174
175  // Parse TCP options in the header.
176  void parseOptions(const char* data, uint32_t len);
177
178  // Apply a TCP option that has been read from the header.
179  void applyOption(char kind, const char* data, uint32_t len);
180
181  // Apply window scale option.
182  void applyWindowScaleOption(uint8_t scale_factor);
183
184  // Resize the send buffer with |new_size| in bytes.
185  void resizeSendBuffer(uint32_t new_size);
186
187  // Resize the receive buffer with |new_size| in bytes. This call adjusts
188  // window scale factor |m_swnd_scale| accordingly.
189  void resizeReceiveBuffer(uint32_t new_size);
190
191  IPseudoTcpNotify* m_notify;
192  enum Shutdown { SD_NONE, SD_GRACEFUL, SD_FORCEFUL } m_shutdown;
193  int m_error;
194
195  // TCB data
196  TcpState m_state;
197  uint32_t m_conv;
198  bool m_bReadEnable, m_bWriteEnable, m_bOutgoing;
199  uint32_t m_lasttraffic;
200
201  // Incoming data
202  typedef std::list<RSegment> RList;
203  RList m_rlist;
204  uint32_t m_rbuf_len, m_rcv_nxt, m_rcv_wnd, m_lastrecv;
205  uint8_t m_rwnd_scale;  // Window scale factor.
206  rtc::FifoBuffer m_rbuf;
207
208  // Outgoing data
209  SList m_slist;
210  uint32_t m_sbuf_len, m_snd_nxt, m_snd_wnd, m_lastsend, m_snd_una;
211  uint8_t m_swnd_scale;  // Window scale factor.
212  rtc::FifoBuffer m_sbuf;
213
214  // Maximum segment size, estimated protocol level, largest segment sent
215  uint32_t m_mss, m_msslevel, m_largest, m_mtu_advise;
216  // Retransmit timer
217  uint32_t m_rto_base;
218
219  // Timestamp tracking
220  uint32_t m_ts_recent, m_ts_lastack;
221
222  // Round-trip calculation
223  uint32_t m_rx_rttvar, m_rx_srtt, m_rx_rto;
224
225  // Congestion avoidance, Fast retransmit/recovery, Delayed ACKs
226  uint32_t m_ssthresh, m_cwnd;
227  uint8_t m_dup_acks;
228  uint32_t m_recover;
229  uint32_t m_t_ack;
230
231  // Configuration options
232  bool m_use_nagling;
233  uint32_t m_ack_delay;
234
235  // This is used by unit tests to test backward compatibility of
236  // PseudoTcp implementations that don't support window scaling.
237  bool m_support_wnd_scale;
238};
239
240}  // namespace cricket
241
242#endif  // WEBRTC_P2P_BASE_PSEUDOTCP_H_
243