3 * the main header file for libswift, normally you should only read this one
5 * Created by Victor Grishchenko on 3/6/09.
6 * Copyright 2009 Delft University of Technology. All rights reserved.
15 HANDSHAKE 00, channelid
16 Communicates the channel id of the sender. The
17 initial handshake packet also has the root hash
20 DATA 01, bin_32, buffer
24 ACKTS 08, bin_32, timestamp_32
25 Confirms successfull delivery of data. Used for
26 congestion control, as well.
29 Practical value of "hints" is to avoid overlap, mostly.
30 Hints might be lost in the network or ignored.
31 Peer might send out data without a hint.
32 Hint which was not responded (by DATA) in some RTTs
33 is considered to be ignored.
34 As peers cant pick randomly kilobyte here and there,
35 they send out "long hints" for non-base bins.
37 HASH 04, bin_32, sha1hash
38 SHA1 hash tree hashes for data verification. The
39 connection to a fresh peer starts with bootstrapping
40 him with peak hashes. Later, before sending out
41 any data, a peer sends the necessary uncle hashes.
43 PEX+/PEX- 05/06, ipv4 addr, port
44 Peer exchange messages; reports all connected and
45 disconected peers. Might has special meaning (as
46 in the case with swarm supervisors).
53 #include "compat/stdint.h"
68 #define NOW Datagram::now
70 /** tintbin is basically a pair<tint,bin64_t> plus some nice operators.
71 Most frequently used in different queues (acknowledgements, requests,
76 tintbin(const tintbin& b) : time(b.time), bin(b.bin) {}
77 tintbin() : time(TINT_NEVER), bin(bin64_t::NONE) {}
78 tintbin(tint time_, bin64_t bin_) : time(time_), bin(bin_) {}
79 tintbin(bin64_t bin_) : time(NOW), bin(bin_) {}
80 bool operator < (const tintbin& b) const
81 { return time > b.time; }
82 bool operator == (const tintbin& b) const
83 { return time==b.time && bin==b.bin; }
84 bool operator != (const tintbin& b) const
85 { return !(*this==b); }
88 typedef std::deque<tintbin> tbqueue;
89 typedef std::deque<bin64_t> binqueue;
90 typedef Address Address;
92 /** A heap (priority queue) for timestamped bin numbers (tintbins). */
96 int size () const { return data_.size(); }
97 bool is_empty () const { return data_.empty(); }
99 tintbin ret = data_.front();
100 std::pop_heap(data_.begin(),data_.end());
104 void push(const tintbin& tb) {
106 push_heap(data_.begin(),data_.end());
108 const tintbin& peek() const {
109 return data_.front();
113 /** swift protocol message types; these are used on the wire. */
123 P2TP_SIGNED_HASH = 7,
124 P2TP_MESSAGE_COUNT = 8
128 class CongestionController;
132 /** A class representing single file transfer. */
137 /** A constructor. Open/submit/retrieve a file.
138 * @param file_name the name of the file
139 * @param root_hash the root hash of the file; zero hash if the file
140 is newly submitted */
141 FileTransfer(const char *file_name, const Sha1Hash& root_hash=Sha1Hash::ZERO);
143 /** Close everything. */
147 /** While we need to feed ACKs to every peer, we try (1) avoid
148 unnecessary duplication and (2) keep minimum state. Thus,
149 we use a rotating queue of bin completion events. */
150 //bin64_t RevealAck (uint64_t& offset);
151 /** Rotating queue read for channels of this transmission. */
152 int RevealChannel (int& i);
154 /** Find transfer by the root hash. */
155 static FileTransfer* Find (const Sha1Hash& hash);
156 /** Find transfer by the file descriptor. */
157 static FileTransfer* file (int fd) {
158 return fd<files.size() ? files[fd] : NULL;
161 /** The binmap for data already retrieved and checked. */
162 binmap_t& ack_out () { return file_.ack_out(); }
163 /** Piece picking strategy used by this transfer. */
164 PiecePicker& picker () { return *picker_; }
165 /** The number of channels working for this transfer. */
166 int channel_count () const { return hs_in_.size(); }
167 /** Hash tree checked file; all the hashes and data are kept here. */
168 HashTree& file() { return file_; }
169 /** File descriptor for the data file. */
170 int fd () const { return file_.file_descriptor(); }
171 /** Root SHA1 hash of the transfer (and the data file). */
172 const Sha1Hash& root_hash () const { return file_.root_hash(); }
176 static std::vector<FileTransfer*> files;
180 /** Piece picker strategy. */
181 PiecePicker* picker_;
183 /** Channels working for this transfer. */
186 std::deque<Address> pex_in_;
188 /** Messages we are accepting. */
194 void OnDataIn (bin64_t pos);
195 void OnPexIn (const Address& addr);
197 friend class Channel;
198 friend uint64_t Size (int fdes);
199 friend bool IsComplete (int fdes);
200 friend uint64_t Complete (int fdes);
201 friend uint64_t SeqComplete (int fdes);
202 friend int Open (const char* filename, const Sha1Hash& hash) ;
203 friend void Close (int fd) ;
207 /** PiecePicker implements some strategy of choosing (picking) what
208 to request next, given the possible range of choices:
209 data acknowledged by the peer minus data already retrieved.
210 May pick sequentially, do rarest first or in some other way. */
213 virtual void Randomize (uint64_t twist) = 0;
214 /** The piece picking method itself.
215 * @param offered the daata acknowledged by the peer
216 * @param max_width maximum number of packets to ask for
217 * @param expires (not used currently) when to consider request expired
218 * @return the bin number to request */
219 virtual bin64_t Pick (binmap_t& offered, uint64_t max_width, tint expires) = 0;
225 virtual void AddPeer (const Address& addr, const Sha1Hash& root) = 0;
226 virtual Address GetPeer (const Sha1Hash& for_root) = 0;
232 DataStorer (const Sha1Hash& id, size_t size);
233 virtual size_t ReadData (bin64_t pos,uint8_t** buf) = 0;
234 virtual size_t WriteData (bin64_t pos, uint8_t* buf, size_t len) = 0;
238 /** P2TP channel's "control block"; channels loosely correspond to TCP
239 connections or FTP sessions; one channel is created for one file
240 being transferred between two peers. As we don't need buffers and
241 lots of other TCP stuff, sizeof(Channel+members) must be below 1K.
242 Normally, API users do not deal with this class. */
245 Channel (FileTransfer* file, int socket=-1, Address peer=Address());
256 static const char* SEND_CONTROL_MODES[];
259 RecvDatagram (int socket);
260 static void Loop (tint till);
262 void Recv (Datagram& dgram);
265 void OnAck (Datagram& dgram);
266 void OnTs (Datagram& dgram);
267 bin64_t OnData (Datagram& dgram);
268 void OnHint (Datagram& dgram);
269 void OnHash (Datagram& dgram);
270 void OnPex (Datagram& dgram);
271 void OnHandshake (Datagram& dgram);
272 void AddHandshake (Datagram& dgram);
273 bin64_t AddData (Datagram& dgram);
274 void AddAck (Datagram& dgram);
275 void AddTs (Datagram& dgram);
276 void AddHint (Datagram& dgram);
277 void AddUncleHashes (Datagram& dgram, bin64_t pos);
278 void AddPeakHashes (Datagram& dgram);
279 void AddPex (Datagram& dgram);
281 void BackOffOnLosses (float ratio=0.5);
282 tint SwitchSendControl (int control_mode);
283 tint NextSendTime ();
284 tint KeepAliveNextSendTime ();
285 tint PingPongNextSendTime ();
286 tint CwndRateNextSendTime ();
287 tint SlowStartNextSendTime ();
288 tint AimdNextSendTime ();
289 tint LedbatNextSendTime ();
291 static int MAX_REORDERING;
294 static tint MAX_SEND_INTERVAL;
295 static tint LEDBAT_TARGET;
296 static float LEDBAT_GAIN;
297 static tint LEDBAT_DELAY_BIN;
298 static bool SELF_CONN_OK;
300 const std::string id_string () const;
301 /** A channel is "established" if had already sent and received packets. */
302 bool is_established () { return peer_channel_id_ && own_id_mentioned_; }
303 FileTransfer& transfer() { return *transfer_; }
304 HashTree& file () { return transfer_->file(); }
305 const Address& peer() const { return peer_; }
306 tint ack_timeout () {
307 return rtt_avg_ + std::max(dev_avg_,MIN_DEV)*4;
309 uint32_t id () const { return id_; }
311 static int DecodeID(int scrambled);
312 static int EncodeID(int unscrambled);
313 static Channel* channel(int i) {
314 return i<channels.size()?channels[i]:NULL;
316 static void CloseTransfer (FileTransfer* trans);
317 static SOCKET default_socket() { return sockets[0]; }
320 /** Channel id: index in the channel array. */
322 /** Socket address of the peer. */
324 /** The UDP socket fd. */
326 /** Descriptor of the file in question. */
327 FileTransfer* transfer_;
328 /** Peer channel id; zero if we are trying to open a channel. */
329 uint32_t peer_channel_id_;
330 bool own_id_mentioned_;
331 /** Peer's progress, based on acknowledgements. */
333 /** Last data received; needs to be acked immediately. */
335 bin64_t data_in_dbl_;
336 /** The history of data sent and still unacknowledged. */
338 bin64_t data_out_cap_;
339 /** Index in the history array. */
341 /** Transmit schedule: in most cases filled with the peer's hints */
343 /** Hints sent (to detect and reschedule ignored hints). */
345 uint64_t hint_out_size_;
346 /** Types of messages the peer accepts. */
349 //tint last_send_time, last_recv_time;
352 /** Smoothed averages for RTT, RTT deviation and data interarrival periods. */
353 tint rtt_avg_, dev_avg_, dip_avg_;
354 tint last_send_time_;
355 tint last_recv_time_;
356 tint last_data_out_time_;
357 tint last_data_in_time_;
358 tint last_loss_time_;
359 tint next_send_time_;
360 tint peer_send_time_;
361 /** Congestion window; TODO: int, bytes. */
363 /** Data sending interval. */
365 /** The congestion control strategy. */
367 /** Datagrams (not data) sent since last recv. */
368 int sent_since_recv_;
369 /** Recent acknowlegements for data previously sent. */
370 int ack_rcvd_recent_;
371 /** Recent non-acknowlegements (losses) of data previously sent. */
372 int ack_not_rcvd_recent_;
373 /** LEDBAT one-way delay machinery */
374 tint owd_min_bins_[4];
376 tint owd_min_bin_start_;
377 tint owd_current_[4];
383 int PeerBPS() const {
384 return TINT_SEC / dip_avg_ * 1024;
386 /** Get a request for one packet from the queue of peer's requests. */
387 bin64_t DequeueHint();
388 void CleanDataOut (bin64_t acks_pos=bin64_t::NONE);
389 void CleanStaleHintOut();
390 void CleanHintOut(bin64_t pos);
393 static PeerSelector* peer_selector;
395 static SOCKET sockets[8];
396 static int socket_count;
397 static tint last_tick;
398 static tbheap send_queue;
400 static Address tracker;
401 static std::vector<Channel*> channels;
403 friend int Listen (Address addr);
404 friend void Shutdown (int sock_des);
405 friend void AddPeer (Address address, const Sha1Hash& root);
406 friend void SetTracker(const Address& tracker);
407 friend int Open (const char*, const Sha1Hash&) ; // FIXME
413 /*************** The top-level API ****************/
414 /** Start listening a port. Returns socket descriptor. */
415 int Listen (Address addr);
416 /** Run send/receive loop for the specified amount of time. */
417 void Loop (tint till);
418 /** Stop listening to a port. */
419 void Shutdown (int sock_des=-1);
421 /** Open a file, start a transmission; fill it with content for a given root hash;
422 in case the hash is omitted, the file is a fresh submit. */
423 int Open (const char* filename, const Sha1Hash& hash=Sha1Hash::ZERO) ;
424 /** Get the root hash for the transmission. */
425 const Sha1Hash& RootMerkleHash (int file) ;
426 /** Close a file and a transmission. */
427 void Close (int fd) ;
428 /** Add a possible peer which participares in a given transmission. In the case
429 root hash is zero, the peer might be talked to regarding any transmission
430 (likely, a tracker, cache or an archive). */
431 void AddPeer (Address address, const Sha1Hash& root=Sha1Hash::ZERO);
433 void SetTracker(const Address& tracker);
435 /** Returns size of the file in bytes, 0 if unknown. Might be rounded up to a kilobyte
436 before the transmission is complete. */
437 uint64_t Size (int fdes);
438 /** Returns the amount of retrieved and verified data, in bytes.
439 A 100% complete transmission has Size()==Complete(). */
440 uint64_t Complete (int fdes);
441 bool IsComplete (int fdes);
442 /** Returns the number of bytes that are complete sequentially, starting from the
443 beginning, till the first not-yet-retrieved packet. */
444 uint64_t SeqComplete (int fdes);
447 //uint32_t Width (const tbinvec& v);
450 /** Must be called by any client using the library */
451 void LibraryInit(void);