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
23 ACK 02, 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).
63 #define NOW Datagram::now
65 /** tintbin is basically a pair<tint,bin64_t> plus some nice operators.
66 Most frequently used in different queues (acknowledgements, requests,
71 tintbin(const tintbin& b) : time(b.time), bin(b.bin) {}
72 tintbin() : time(TINT_NEVER), bin(bin64_t::NONE) {}
73 tintbin(tint time_, bin64_t bin_) : time(time_), bin(bin_) {}
74 tintbin(bin64_t bin_) : time(NOW), bin(bin_) {}
75 bool operator < (const tintbin& b) const
76 { return time > b.time; }
77 bool operator == (const tintbin& b) const
78 { return time==b.time && bin==b.bin; }
79 bool operator != (const tintbin& b) const
80 { return !(*this==b); }
83 typedef std::deque<tintbin> tbqueue;
84 typedef std::deque<bin64_t> binqueue;
85 typedef Address Address;
87 /** A heap (priority queue) for timestamped bin numbers (tintbins). */
91 int size () const { return data_.size(); }
92 bool is_empty () const { return data_.empty(); }
94 tintbin ret = data_.front();
95 std::pop_heap(data_.begin(),data_.end());
99 void push(const tintbin& tb) {
101 push_heap(data_.begin(),data_.end());
103 const tintbin& peek() const {
104 return data_.front();
108 /** swift protocol message types; these are used on the wire. */
117 SWIFT_SIGNED_HASH = 7,
119 SWIFT_MSGTYPE_RCVD = 9,
120 SWIFT_MESSAGE_COUNT = 10
124 class CongestionController;
128 /** A class representing single file transfer. */
133 /** A constructor. Open/submit/retrieve a file.
134 * @param file_name the name of the file
135 * @param root_hash the root hash of the file; zero hash if the file
136 is newly submitted */
137 FileTransfer(const char *file_name, const Sha1Hash& root_hash=Sha1Hash::ZERO);
139 /** Close everything. */
143 /** While we need to feed ACKs to every peer, we try (1) avoid
144 unnecessary duplication and (2) keep minimum state. Thus,
145 we use a rotating queue of bin completion events. */
146 //bin64_t RevealAck (uint64_t& offset);
147 /** Rotating queue read for channels of this transmission. */
148 int RevealChannel (int& i);
150 /** Find transfer by the root hash. */
151 static FileTransfer* Find (const Sha1Hash& hash);
152 /** Find transfer by the file descriptor. */
153 static FileTransfer* file (int fd) {
154 return fd<files.size() ? files[fd] : NULL;
157 /** The binmap for data already retrieved and checked. */
158 binmap_t& ack_out () { return file_.ack_out(); }
159 /** Piece picking strategy used by this transfer. */
160 PiecePicker& picker () { return *picker_; }
161 /** The number of channels working for this transfer. */
162 int channel_count () const { return hs_in_.size(); }
163 /** Hash tree checked file; all the hashes and data are kept here. */
164 HashTree& file() { return file_; }
165 /** File descriptor for the data file. */
166 int fd () const { return file_.file_descriptor(); }
167 /** Root SHA1 hash of the transfer (and the data file). */
168 const Sha1Hash& root_hash () const { return file_.root_hash(); }
172 static std::vector<FileTransfer*> files;
176 /** Piece picker strategy. */
177 PiecePicker* picker_;
179 /** Channels working for this transfer. */
182 std::deque<Address> pex_in_;
184 /** Messages we are accepting. */
190 void OnDataIn (bin64_t pos);
191 void OnPexIn (const Address& addr);
193 friend class Channel;
194 friend uint64_t Size (int fdes);
195 friend bool IsComplete (int fdes);
196 friend uint64_t Complete (int fdes);
197 friend uint64_t SeqComplete (int fdes);
198 friend int Open (const char* filename, const Sha1Hash& hash) ;
199 friend void Close (int fd) ;
203 /** PiecePicker implements some strategy of choosing (picking) what
204 to request next, given the possible range of choices:
205 data acknowledged by the peer minus data already retrieved.
206 May pick sequentially, do rarest first or in some other way. */
209 virtual void Randomize (uint64_t twist) = 0;
210 /** The piece picking method itself.
211 * @param offered the daata acknowledged by the peer
212 * @param max_width maximum number of packets to ask for
213 * @param expires (not used currently) when to consider request expired
214 * @return the bin number to request */
215 virtual bin64_t Pick (binmap_t& offered, uint64_t max_width, tint expires) = 0;
216 virtual ~PiecePicker() {}
222 virtual void AddPeer (const Address& addr, const Sha1Hash& root) = 0;
223 virtual Address GetPeer (const Sha1Hash& for_root) = 0;
229 DataStorer (const Sha1Hash& id, size_t size);
230 virtual size_t ReadData (bin64_t pos,uint8_t** buf) = 0;
231 virtual size_t WriteData (bin64_t pos, uint8_t* buf, size_t len) = 0;
235 /** swift channel's "control block"; channels loosely correspond to TCP
236 connections or FTP sessions; one channel is created for one file
237 being transferred between two peers. As we don't need buffers and
238 lots of other TCP stuff, sizeof(Channel+members) must be below 1K.
239 Normally, API users do not deal with this class. */
242 Channel (FileTransfer* file, int socket=-1, Address peer=Address());
254 static const char* SEND_CONTROL_MODES[];
257 RecvDatagram (int socket);
258 static void Loop (tint till);
260 void Recv (Datagram& dgram);
264 void OnAck (Datagram& dgram);
265 void OnHave (Datagram& dgram);
266 bin64_t OnData (Datagram& dgram);
267 void OnHint (Datagram& dgram);
268 void OnHash (Datagram& dgram);
269 void OnPex (Datagram& dgram);
270 void OnHandshake (Datagram& dgram);
271 void AddHandshake (Datagram& dgram);
272 bin64_t AddData (Datagram& dgram);
273 void AddAck (Datagram& dgram);
274 void AddHave (Datagram& dgram);
275 void AddHint (Datagram& dgram);
276 void AddUncleHashes (Datagram& dgram, bin64_t pos);
277 void AddPeakHashes (Datagram& dgram);
278 void AddPex (Datagram& dgram);
280 void BackOffOnLosses (float ratio=0.5);
281 tint SwitchSendControl (int control_mode);
282 tint NextSendTime ();
283 tint KeepAliveNextSendTime ();
284 tint PingPongNextSendTime ();
285 tint CwndRateNextSendTime ();
286 tint SlowStartNextSendTime ();
287 tint AimdNextSendTime ();
288 tint LedbatNextSendTime ();
290 static int MAX_REORDERING;
293 static tint MAX_SEND_INTERVAL;
294 static tint LEDBAT_TARGET;
295 static float LEDBAT_GAIN;
296 static tint LEDBAT_DELAY_BIN;
297 static bool SELF_CONN_OK;
298 static tint MAX_POSSIBLE_RTT;
299 static FILE* debug_file;
301 const std::string id_string () const;
302 /** A channel is "established" if had already sent and received packets. */
303 bool is_established () { return peer_channel_id_ && own_id_mentioned_; }
304 FileTransfer& transfer() { return *transfer_; }
305 HashTree& file () { return transfer_->file(); }
306 const Address& peer() const { return peer_; }
307 tint ack_timeout () {
308 tint dev = dev_avg_ < MIN_DEV ? MIN_DEV : dev_avg_;
309 tint tmo = rtt_avg_ + dev * 4;
310 return tmo < 30*TINT_SEC ? tmo : 30*TINT_SEC;
312 uint32_t id () const { return id_; }
314 static int DecodeID(int scrambled);
315 static int EncodeID(int unscrambled);
316 static Channel* channel(int i) {
317 return i<channels.size()?channels[i]:NULL;
319 static void CloseTransfer (FileTransfer* trans);
320 static SOCKET default_socket() { return sockets[0]; }
323 /** Channel id: index in the channel array. */
325 /** Socket address of the peer. */
327 /** The UDP socket fd. */
329 /** Descriptor of the file in question. */
330 FileTransfer* transfer_;
331 /** Peer channel id; zero if we are trying to open a channel. */
332 uint32_t peer_channel_id_;
333 bool own_id_mentioned_;
334 /** Peer's progress, based on acknowledgements. */
336 /** Last data received; needs to be acked immediately. */
338 bin64_t data_in_dbl_;
339 /** The history of data sent and still unacknowledged. */
341 /** Timeouted data (potentially to be retransmitted). */
342 tbqueue data_out_tmo_;
343 bin64_t data_out_cap_;
344 /** Index in the history array. */
346 /** Transmit schedule: in most cases filled with the peer's hints */
348 /** Hints sent (to detect and reschedule ignored hints). */
350 uint64_t hint_out_size_;
351 /** Types of messages the peer accepts. */
354 //tint last_send_time, last_recv_time;
357 /** Smoothed averages for RTT, RTT deviation and data interarrival periods. */
358 tint rtt_avg_, dev_avg_, dip_avg_;
359 tint last_send_time_;
360 tint last_recv_time_;
361 tint last_data_out_time_;
362 tint last_data_in_time_;
363 tint last_loss_time_;
364 tint next_send_time_;
365 /** Congestion window; TODO: int, bytes. */
367 /** Data sending interval. */
369 /** The congestion control strategy. */
371 /** Datagrams (not data) sent since last recv. */
372 int sent_since_recv_;
373 /** Recent acknowlegements for data previously sent. */
374 int ack_rcvd_recent_;
375 /** Recent non-acknowlegements (losses) of data previously sent. */
376 int ack_not_rcvd_recent_;
377 /** LEDBAT one-way delay machinery */
378 tint owd_min_bins_[4];
380 tint owd_min_bin_start_;
381 tint owd_current_[4];
387 int PeerBPS() const {
388 return TINT_SEC / dip_avg_ * 1024;
390 /** Get a request for one packet from the queue of peer's requests. */
391 bin64_t DequeueHint();
392 bin64_t ImposeHint();
393 void TimeoutDataOut ();
394 void CleanStaleHintOut();
395 void CleanHintOut(bin64_t pos);
398 static PeerSelector* peer_selector;
400 static SOCKET sockets[8];
401 static int socket_count;
402 static tint last_tick;
403 static tbheap send_queue;
405 static Address tracker;
406 static std::vector<Channel*> channels;
408 friend int Listen (Address addr);
409 friend void Shutdown (int sock_des);
410 friend void AddPeer (Address address, const Sha1Hash& root);
411 friend void SetTracker(const Address& tracker);
412 friend int Open (const char*, const Sha1Hash&) ; // FIXME
418 /*************** The top-level API ****************/
419 /** Start listening a port. Returns socket descriptor. */
420 int Listen (Address addr);
421 /** Run send/receive loop for the specified amount of time. */
422 void Loop (tint till);
423 /** Stop listening to a port. */
424 void Shutdown (int sock_des=-1);
426 /** Open a file, start a transmission; fill it with content for a given root hash;
427 in case the hash is omitted, the file is a fresh submit. */
428 int Open (const char* filename, const Sha1Hash& hash=Sha1Hash::ZERO) ;
429 /** Get the root hash for the transmission. */
430 const Sha1Hash& RootMerkleHash (int file) ;
431 /** Close a file and a transmission. */
432 void Close (int fd) ;
433 /** Add a possible peer which participares in a given transmission. In the case
434 root hash is zero, the peer might be talked to regarding any transmission
435 (likely, a tracker, cache or an archive). */
436 void AddPeer (Address address, const Sha1Hash& root=Sha1Hash::ZERO);
438 void SetTracker(const Address& tracker);
440 /** Returns size of the file in bytes, 0 if unknown. Might be rounded up to a kilobyte
441 before the transmission is complete. */
442 uint64_t Size (int fdes);
443 /** Returns the amount of retrieved and verified data, in bytes.
444 A 100% complete transmission has Size()==Complete(). */
445 uint64_t Complete (int fdes);
446 bool IsComplete (int fdes);
447 /** Returns the number of bytes that are complete sequentially, starting from the
448 beginning, till the first not-yet-retrieved packet. */
449 uint64_t SeqComplete (int fdes);
452 //uint32_t Width (const tbinvec& v);
455 /** Must be called by any client using the library */
456 void LibraryInit(void);
462 #define dprintf(...) { if (Channel::debug_file) fprintf(Channel::debug_file,__VA_ARGS__); }
464 #define dprintf(...) {}
466 #define eprintf(...) fprintf(stderr,__VA_ARGS__)