1 /* Copyright (c) 2012-2020. The SimGrid Team. All rights reserved. */
3 /* This program is free software; you can redistribute it and/or modify it
4 * under the terms of the license (GNU LGPL) which comes with this package. */
6 #include "bittorrent-peer.h"
7 #include "bittorrent-messages.h"
8 #include "connection.h"
10 #include <simgrid/msg.h>
13 #include <stdio.h> /* snprintf */
15 XBT_LOG_NEW_DEFAULT_CATEGORY(msg_peers, "Messages specific for the peers");
18 * User parameters for transferred file data. For the test, the default values are :
19 * File size: 10 pieces * 5 blocks/piece * 16384 bytes/block = 819200 bytes
21 #define FILE_PIECES 10UL
22 #define PIECES_BLOCKS 5UL
23 #define BLOCK_SIZE 16384
24 static const unsigned long int FILE_SIZE = FILE_PIECES * PIECES_BLOCKS * BLOCK_SIZE;
26 /** Number of blocks asked by each request */
27 #define BLOCKS_REQUESTED 2
29 #define SLEEP_DURATION 1
31 int count_pieces(unsigned int bitfield)
34 unsigned int n = bitfield;
42 int peer_has_not_piece(const s_peer_t* peer, unsigned int piece)
44 return !(peer->bitfield & 1U << piece);
47 /** Check that a piece is not currently being download by the peer. */
48 int peer_is_not_downloading_piece(const s_peer_t* peer, unsigned int piece)
50 return !(peer->current_pieces & 1U << piece);
53 void get_status(char** status, unsigned int bitfield)
55 for (int i = FILE_PIECES - 1; i >= 0; i--)
56 (*status)[i] = (bitfield & (1U << i)) ? '1' : '0';
57 (*status)[FILE_PIECES] = '\0';
60 /** Peer main function */
61 int peer(int argc, char* argv[])
64 xbt_assert(argc == 3 || argc == 4, "Wrong number of arguments");
67 peer_t peer = peer_init(xbt_str_parse_int(argv[1], "Invalid ID: %s"), argc == 4 ? 1 : 0);
70 double deadline = xbt_str_parse_double(argv[2], "Invalid deadline: %s");
71 xbt_assert(deadline > 0, "Wrong deadline supplied");
73 char* status = xbt_malloc0(FILE_PIECES + 1);
74 get_status(&status, peer->bitfield);
75 XBT_INFO("Hi, I'm joining the network with id %d", peer->id);
76 // Getting peer data from the tracker.
77 if (get_peers_data(peer)) {
78 XBT_DEBUG("Got %d peers from the tracker. Current status is: %s", xbt_dict_length(peer->peers), status);
79 peer->begin_receive_time = MSG_get_clock();
80 MSG_mailbox_set_async(peer->mailbox);
81 if (has_finished(peer->bitfield)) {
82 send_handshake_all(peer);
84 leech_loop(peer, deadline);
86 seed_loop(peer, deadline);
88 XBT_INFO("Couldn't contact the tracker.");
91 get_status(&status, peer->bitfield);
92 XBT_INFO("Here is my current status: %s", status);
93 if (peer->comm_received) {
94 MSG_comm_destroy(peer->comm_received);
102 /** @brief Peer main loop when it is leeching.
103 * @param peer peer data
104 * @param deadline time at which the peer has to leave
106 void leech_loop(peer_t peer, double deadline)
108 double next_choked_update = MSG_get_clock() + UPDATE_CHOKED_INTERVAL;
109 XBT_DEBUG("Start downloading.");
111 /* Send a "handshake" message to all the peers it got (since it couldn't have gotten more than 50 peers) */
112 send_handshake_all(peer);
113 XBT_DEBUG("Starting main leech loop");
115 while (MSG_get_clock() < deadline && count_pieces(peer->bitfield) < FILE_PIECES) {
116 if (peer->comm_received == NULL) {
117 peer->task_received = NULL;
118 peer->comm_received = MSG_task_irecv(&peer->task_received, peer->mailbox);
120 if (MSG_comm_test(peer->comm_received)) {
121 msg_error_t status = MSG_comm_get_status(peer->comm_received);
122 MSG_comm_destroy(peer->comm_received);
123 peer->comm_received = NULL;
124 if (status == MSG_OK) {
125 handle_message(peer, peer->task_received);
128 // We don't execute the choke algorithm if we don't already have a piece
129 if (MSG_get_clock() >= next_choked_update && count_pieces(peer->bitfield) > 0) {
130 update_choked_peers(peer);
131 next_choked_update += UPDATE_CHOKED_INTERVAL;
133 MSG_process_sleep(SLEEP_DURATION);
137 if (has_finished(peer->bitfield))
138 XBT_DEBUG("%d becomes a seeder", peer->id);
141 /** @brief Peer main loop when it is seeding
142 * @param peer peer data
143 * @param deadline time when the peer will leave
145 void seed_loop(peer_t peer, double deadline)
147 double next_choked_update = MSG_get_clock() + UPDATE_CHOKED_INTERVAL;
148 XBT_DEBUG("Start seeding.");
149 // start the main seed loop
150 while (MSG_get_clock() < deadline) {
151 if (peer->comm_received == NULL) {
152 peer->task_received = NULL;
153 peer->comm_received = MSG_task_irecv(&peer->task_received, peer->mailbox);
155 if (MSG_comm_test(peer->comm_received)) {
156 msg_error_t status = MSG_comm_get_status(peer->comm_received);
157 MSG_comm_destroy(peer->comm_received);
158 peer->comm_received = NULL;
159 if (status == MSG_OK) {
160 handle_message(peer, peer->task_received);
163 if (MSG_get_clock() >= next_choked_update) {
164 update_choked_peers(peer);
165 // TODO: Change the choked peer algorithm when seeding.
166 next_choked_update += UPDATE_CHOKED_INTERVAL;
168 MSG_process_sleep(SLEEP_DURATION);
174 /** @brief Retrieves the peer list from the tracker
175 * @param peer current peer data
177 int get_peers_data(const s_peer_t* peer)
180 double timeout = MSG_get_clock() + GET_PEERS_TIMEOUT;
182 // Build the task to send to the tracker
183 tracker_task_data_t data =
184 tracker_task_data_new(MSG_host_get_name(MSG_host_self()), peer->mailbox_tracker, peer->id, 0, 0, FILE_SIZE);
185 msg_task_t task_send = MSG_task_create(NULL, 0, TRACKER_COMM_SIZE, data);
186 while ((success == 0) && MSG_get_clock() < timeout) {
187 XBT_DEBUG("Sending a peer request to the tracker.");
188 msg_error_t status = MSG_task_send_with_timeout(task_send, TRACKER_MAILBOX, GET_PEERS_TIMEOUT);
189 if (status == MSG_OK) {
195 msg_task_t task_received = NULL;
196 while ((success == 0) && MSG_get_clock() < timeout) {
197 msg_comm_t comm_received = MSG_task_irecv(&task_received, peer->mailbox_tracker);
198 msg_error_t status = MSG_comm_wait(comm_received, GET_PEERS_TIMEOUT);
199 if (status == MSG_OK) {
200 tracker_task_data_t data = MSG_task_get_data(task_received);
203 // Add the peers the tracker gave us to our peer list.
204 xbt_dynar_foreach (data->peers, i, peer_id) {
205 if (peer_id != peer->id)
206 xbt_dict_set_ext(peer->peers, (char*)&peer_id, sizeof(int), connection_new(peer_id));
209 // free the communication and the task
210 MSG_comm_destroy(comm_received);
211 tracker_task_data_free(data);
212 MSG_task_destroy(task_received);
219 /** @brief Initialize the peer data.
220 * @param peer peer data
221 * @param id id of the peer to take in the network
222 * @param seed indicates if the peer is a seed.
224 peer_t peer_init(int id, int seed)
226 peer_t peer = xbt_new(s_peer_t, 1);
228 peer->hostname = MSG_host_get_name(MSG_host_self());
230 snprintf(peer->mailbox, MAILBOX_SIZE - 1, "%d", id);
231 snprintf(peer->mailbox_tracker, MAILBOX_SIZE - 1, "tracker_%d", id);
232 peer->peers = xbt_dict_new_homogeneous(NULL);
233 peer->active_peers = xbt_dict_new_homogeneous(NULL);
236 peer->bitfield = (1U << FILE_PIECES) - 1U;
237 peer->bitfield_blocks = (1ULL << (FILE_PIECES * PIECES_BLOCKS)) - 1ULL;
240 peer->bitfield_blocks = 0;
243 peer->current_pieces = 0;
245 peer->pieces_count = xbt_new0(short, FILE_PIECES);
247 peer->comm_received = NULL;
254 /** Destroys a poor peer object. */
255 void peer_free(peer_t peer)
258 connection_t connection;
259 xbt_dict_cursor_t cursor;
260 xbt_dict_foreach (peer->peers, cursor, key, connection) {
261 connection_free(connection);
263 xbt_dict_free(&peer->peers);
264 xbt_dict_free(&peer->active_peers);
265 xbt_free(peer->pieces_count);
269 /** @brief Returns if a peer has finished downloading the file
270 * @param bitfield peer bitfield
272 int has_finished(unsigned int bitfield)
274 return bitfield == (1U << FILE_PIECES) - 1U;
277 int nb_interested_peers(const s_peer_t* peer)
279 xbt_dict_cursor_t cursor = NULL;
281 connection_t connection;
283 xbt_dict_foreach (peer->peers, cursor, key, connection) {
284 if (connection->interested)
290 void update_active_peers_set(const s_peer_t* peer, connection_t remote_peer)
292 if ((remote_peer->interested != 0) && (remote_peer->choked_upload == 0)) {
293 // add in the active peers set
294 xbt_dict_set_ext(peer->active_peers, (char*)&remote_peer->id, sizeof(int), remote_peer);
295 } else if (xbt_dict_get_or_null_ext(peer->active_peers, (char*)&remote_peer->id, sizeof(int))) {
296 xbt_dict_remove_ext(peer->active_peers, (char*)&remote_peer->id, sizeof(int));
300 /** @brief Handle a received message sent by another peer
301 * @param peer Peer data
302 * @param task task received.
304 void handle_message(peer_t peer, msg_task_t task)
306 const char* type_names[10] = {"HANDSHAKE", "CHOKE", "UNCHOKE", "INTERESTED", "NOTINTERESTED",
307 "HAVE", "BITFIELD", "REQUEST", "PIECE", "CANCEL"};
308 message_t message = MSG_task_get_data(task);
309 XBT_DEBUG("Received a %s message from %s (%s)", type_names[message->type], message->mailbox,
310 message->issuer_host_name);
312 connection_t remote_peer;
313 remote_peer = xbt_dict_get_or_null_ext(peer->peers, (char*)&message->peer_id, sizeof(int));
315 switch (message->type) {
316 case MESSAGE_HANDSHAKE:
317 // Check if the peer is in our connection list.
318 if (remote_peer == 0) {
319 xbt_dict_set_ext(peer->peers, (char*)&message->peer_id, sizeof(int), connection_new(message->peer_id));
320 send_handshake(peer, message->mailbox);
322 // Send our bitfield to the peer
323 send_bitfield(peer, message->mailbox);
325 case MESSAGE_BITFIELD:
326 // Update the pieces list
327 update_pieces_count_from_bitfield(peer, message->bitfield);
328 // Store the bitfield
329 remote_peer->bitfield = message->bitfield;
330 xbt_assert(!remote_peer->am_interested, "Should not be interested at first");
331 if (is_interested(peer, remote_peer)) {
332 remote_peer->am_interested = 1;
333 send_interested(peer, message->mailbox);
336 case MESSAGE_INTERESTED:
337 xbt_assert((remote_peer != NULL), "A non-in-our-list peer has sent us a message. WTH ?");
338 // Update the interested state of the peer.
339 remote_peer->interested = 1;
340 update_active_peers_set(peer, remote_peer);
342 case MESSAGE_NOTINTERESTED:
343 xbt_assert((remote_peer != NULL), "A non-in-our-list peer has sent us a message. WTH ?");
344 remote_peer->interested = 0;
345 update_active_peers_set(peer, remote_peer);
347 case MESSAGE_UNCHOKE:
348 xbt_assert((remote_peer != NULL), "A non-in-our-list peer has sent us a message. WTH ?");
349 xbt_assert(remote_peer->choked_download);
350 remote_peer->choked_download = 0;
351 // Send requests to the peer, since it has unchoked us
352 if (remote_peer->am_interested)
353 request_new_piece_to_peer(peer, remote_peer);
356 xbt_assert((remote_peer != NULL), "A non-in-our-list peer has sent us a message. WTH ?");
357 xbt_assert(!remote_peer->choked_download);
358 remote_peer->choked_download = 1;
359 if (remote_peer->current_piece != -1)
360 remove_current_piece(peer, remote_peer, remote_peer->current_piece);
363 XBT_DEBUG("\t for piece %d", message->index);
364 xbt_assert((message->index >= 0 && message->index < FILE_PIECES), "Wrong HAVE message received");
365 remote_peer->bitfield = remote_peer->bitfield | (1U << message->index);
366 peer->pieces_count[message->index]++;
367 // If the piece is in our pieces, we tell the peer that we are interested.
368 if ((remote_peer->am_interested == 0) && peer_has_not_piece(peer, message->index)) {
369 remote_peer->am_interested = 1;
370 send_interested(peer, message->mailbox);
371 if (remote_peer->choked_download == 0)
372 request_new_piece_to_peer(peer, remote_peer);
375 case MESSAGE_REQUEST:
376 xbt_assert(remote_peer->interested);
377 xbt_assert((message->index >= 0 && message->index < FILE_PIECES), "Wrong request received");
378 if (remote_peer->choked_upload == 0) {
379 XBT_DEBUG("\t for piece %d (%d,%d)", message->index, message->block_index,
380 message->block_index + message->block_length);
381 if (!peer_has_not_piece(peer, message->index)) {
382 send_piece(peer, message->mailbox, message->index, message->block_index, message->block_length);
385 XBT_DEBUG("\t for piece %d but he is choked.", message->peer_id);
389 XBT_DEBUG(" \t for piece %d (%d,%d)", message->index, message->block_index,
390 message->block_index + message->block_length);
391 xbt_assert(!remote_peer->choked_download);
392 xbt_assert(remote_peer->choked_download != 1, "Can't received a piece if I'm choked !");
393 xbt_assert((message->index >= 0 && message->index < FILE_PIECES), "Wrong piece received");
394 // TODO: Execute à computation.
395 if (peer_has_not_piece(peer, message->index)) {
396 update_bitfield_blocks(peer, message->index, message->block_index, message->block_length);
397 if (piece_complete(peer, message->index)) {
398 // Removing the piece from our piece list
399 remove_current_piece(peer, remote_peer, message->index);
400 // Setting the fact that we have the piece
401 peer->bitfield = peer->bitfield | (1U << message->index);
402 char* status = xbt_malloc0(FILE_PIECES + 1);
403 get_status(&status, peer->bitfield);
404 XBT_DEBUG("My status is now %s", status);
406 // Sending the information to all the peers we are connected to
407 send_have(peer, message->index);
408 // sending UNINTERESTED to peers that do not have what we want.
409 update_interested_after_receive(peer);
410 } else { // piece not completed
411 send_request_to_peer(peer, remote_peer, message->index); // ask for the next block
414 XBT_DEBUG("However, we already have it");
415 request_new_piece_to_peer(peer, remote_peer);
423 // Update the peer speed.
425 connection_add_speed_value(remote_peer, 1.0 / (MSG_get_clock() - peer->begin_receive_time));
427 peer->begin_receive_time = MSG_get_clock();
429 task_message_free(task);
432 /** Selects the appropriate piece to download and requests it to the remote_peer */
433 void request_new_piece_to_peer(peer_t peer, connection_t remote_peer)
435 int piece = select_piece_to_download(peer, remote_peer);
437 peer->current_pieces |= (1U << (unsigned int)piece);
438 send_request_to_peer(peer, remote_peer, piece);
442 /** remove current_piece from the list of currently downloaded pieces. */
443 void remove_current_piece(peer_t peer, connection_t remote_peer, unsigned int current_piece)
445 peer->current_pieces &= ~(1U << current_piece);
446 remote_peer->current_piece = -1;
449 /** @brief Updates the list of who has a piece from a bitfield
450 * @param peer peer we want to update the list
451 * @param bitfield bitfield
453 void update_pieces_count_from_bitfield(const s_peer_t* peer, unsigned int bitfield)
455 for (int i = 0; i < FILE_PIECES; i++) {
456 if (bitfield & (1U << i)) {
457 peer->pieces_count[i]++;
462 /** @brief Return the piece to be downloaded
463 * There are two cases (as described in "Bittorrent Architecture Protocol", Ryan Toole :
464 * If a piece is partially downloaded, this piece will be selected prioritarily
465 * If the peer has strictly less than 4 pieces, he chooses a piece at random.
466 * If the peer has more than pieces, he downloads the pieces that are the less replicated (rarest policy).
467 * If all pieces have been downloaded or requested, we select a random requested piece (endgame mode).
468 * @param peer: local peer
469 * @param remote_peer: information about the connection
470 * @return the piece to download if possible. -1 otherwise
472 int select_piece_to_download(const s_peer_t* peer, const s_connection_t* remote_peer)
474 int piece = partially_downloaded_piece(peer, remote_peer);
475 // strict priority policy
480 if (count_pieces(peer->current_pieces) >= (FILE_PIECES - count_pieces(peer->bitfield)) &&
481 (is_interested(peer, remote_peer) != 0)) {
482 int nb_interesting_pieces = 0;
483 // compute the number of interesting pieces
484 for (int i = 0; i < FILE_PIECES; i++) {
485 if (peer_has_not_piece(peer, i) && connection_has_piece(remote_peer, i)) {
486 nb_interesting_pieces++;
489 xbt_assert(nb_interesting_pieces != 0);
490 // get a random interesting piece
491 int random_piece_index = rand() % nb_interesting_pieces;
492 int current_index = 0;
493 for (int i = 0; i < FILE_PIECES; i++) {
494 if (peer_has_not_piece(peer, i) && connection_has_piece(remote_peer, i)) {
495 if (random_piece_index == current_index) {
502 xbt_assert(piece != -1);
505 // Random first policy
506 if (count_pieces(peer->bitfield) < 4 && (is_interested_and_free(peer, remote_peer) != 0)) {
507 int nb_interesting_pieces = 0;
508 // compute the number of interesting pieces
509 for (int i = 0; i < FILE_PIECES; i++) {
510 if (peer_has_not_piece(peer, i) && connection_has_piece(remote_peer, i) &&
511 peer_is_not_downloading_piece(peer, i)) {
512 nb_interesting_pieces++;
515 xbt_assert(nb_interesting_pieces != 0);
516 // get a random interesting piece
517 int random_piece_index = rand() % nb_interesting_pieces;
518 int current_index = 0;
519 for (int i = 0; i < FILE_PIECES; i++) {
520 if (peer_has_not_piece(peer, i) && connection_has_piece(remote_peer, i) &&
521 peer_is_not_downloading_piece(peer, i)) {
522 if (random_piece_index == current_index) {
529 xbt_assert(piece != -1);
531 } else { // Rarest first policy
532 short min = SHRT_MAX;
533 int nb_min_pieces = 0;
534 int current_index = 0;
535 // compute the smallest number of copies of available pieces
536 for (int i = 0; i < FILE_PIECES; i++) {
537 if (peer->pieces_count[i] < min && peer_has_not_piece(peer, i) && connection_has_piece(remote_peer, i) &&
538 peer_is_not_downloading_piece(peer, i))
539 min = peer->pieces_count[i];
541 xbt_assert(min != SHRT_MAX || (is_interested_and_free(peer, remote_peer) == 0));
542 // compute the number of rarest pieces
543 for (int i = 0; i < FILE_PIECES; i++) {
544 if (peer->pieces_count[i] == min && peer_has_not_piece(peer, i) && connection_has_piece(remote_peer, i) &&
545 peer_is_not_downloading_piece(peer, i))
548 xbt_assert(nb_min_pieces != 0 || (is_interested_and_free(peer, remote_peer) == 0));
549 // get a random rarest piece
550 int random_rarest_index = 0;
551 if (nb_min_pieces > 0) {
552 random_rarest_index = rand() % nb_min_pieces;
554 for (int i = 0; i < FILE_PIECES; i++) {
555 if (peer->pieces_count[i] == min && peer_has_not_piece(peer, i) && connection_has_piece(remote_peer, i) &&
556 peer_is_not_downloading_piece(peer, i)) {
557 if (random_rarest_index == current_index) {
564 xbt_assert(piece != -1 || (is_interested_and_free(peer, remote_peer) == 0));
569 /** @brief Update the list of current choked and unchoked peers, using the choke algorithm
570 * @param peer the current peer
572 void update_choked_peers(peer_t peer)
574 if (nb_interested_peers(peer) == 0)
576 XBT_DEBUG("(%d) update_choked peers %u active peers", peer->id, xbt_dict_size(peer->active_peers));
577 // update the current round
578 peer->round = (peer->round + 1) % 3;
580 char* choked_key = NULL;
581 connection_t chosen_peer = NULL;
582 connection_t choked_peer = NULL;
583 // remove a peer from the list
584 xbt_dict_cursor_t cursor = NULL;
585 xbt_dict_cursor_first(peer->active_peers, &cursor);
586 if (!xbt_dict_is_empty(peer->active_peers)) {
587 choked_key = xbt_dict_cursor_get_key(cursor);
588 choked_peer = xbt_dict_cursor_get_data(cursor);
590 xbt_dict_cursor_free(&cursor);
592 /**If we are currently seeding, we unchoke the peer which has been unchoked the last time.*/
593 if (has_finished(peer->bitfield)) {
594 connection_t connection;
595 double unchoke_time = MSG_get_clock() + 1;
597 xbt_dict_foreach (peer->peers, cursor, key, connection) {
598 if (connection->last_unchoke < unchoke_time && (connection->interested != 0) &&
599 (connection->choked_upload != 0)) {
600 unchoke_time = connection->last_unchoke;
601 chosen_peer = connection;
605 // Random optimistic unchoking
606 if (peer->round == 0) {
609 // We choose a random peer to unchoke.
611 if (xbt_dict_length(peer->peers) > 0) {
612 id_chosen = rand() % xbt_dict_length(peer->peers);
615 connection_t connection;
616 xbt_dict_foreach (peer->peers, cursor, key, connection) {
617 if (i == id_chosen) {
618 chosen_peer = connection;
623 xbt_dict_cursor_free(&cursor);
624 xbt_assert(chosen_peer != NULL, "A peer should have been selected at this point");
625 if ((chosen_peer->interested == 0) || (chosen_peer->choked_upload == 0))
628 XBT_DEBUG("Nothing to do, keep going");
630 } while (chosen_peer == NULL && j < MAXIMUM_PEERS);
632 // Use the "fastest download" policy.
633 connection_t connection;
634 double fastest_speed = 0.0;
635 xbt_dict_foreach (peer->peers, cursor, key, connection) {
636 if (connection->peer_speed > fastest_speed && (connection->choked_upload != 0) &&
637 (connection->interested != 0)) {
638 chosen_peer = connection;
639 fastest_speed = connection->peer_speed;
645 if (chosen_peer != NULL)
646 XBT_DEBUG("(%d) update_choked peers unchoked (%d) ; int (%d) ; choked (%d) ", peer->id, chosen_peer->id,
647 chosen_peer->interested, chosen_peer->choked_upload);
649 if (choked_peer != chosen_peer) {
650 if (choked_peer != NULL) {
651 xbt_assert((!choked_peer->choked_upload), "Tries to choked a choked peer");
652 choked_peer->choked_upload = 1;
653 xbt_assert((*((int*)choked_key) == choked_peer->id));
654 update_active_peers_set(peer, choked_peer);
655 XBT_DEBUG("(%d) Sending a CHOKE to %d", peer->id, choked_peer->id);
656 send_choked(peer, choked_peer->mailbox);
658 if (chosen_peer != NULL) {
659 xbt_assert((chosen_peer->choked_upload), "Tries to unchoked an unchoked peer");
660 chosen_peer->choked_upload = 0;
661 xbt_dict_set_ext(peer->active_peers, (char*)&chosen_peer->id, sizeof(int), chosen_peer);
662 chosen_peer->last_unchoke = MSG_get_clock();
663 XBT_DEBUG("(%d) Sending a UNCHOKE to %d", peer->id, chosen_peer->id);
664 update_active_peers_set(peer, chosen_peer);
665 send_unchoked(peer, chosen_peer->mailbox);
670 /** @brief Update "interested" state of peers: send "not interested" to peers that don't have any more pieces we want.
671 * @param peer our peer data
673 void update_interested_after_receive(const s_peer_t* peer)
676 xbt_dict_cursor_t cursor;
677 connection_t connection;
678 xbt_dict_foreach (peer->peers, cursor, key, connection) {
679 if (connection->am_interested != 0) {
681 // Check if the peer still has a piece we want.
682 for (int i = 0; i < FILE_PIECES; i++) {
683 if (peer_has_not_piece(peer, i) && connection_has_piece(connection, i)) {
688 if (!interested) { // no more piece to download from connection
689 connection->am_interested = 0;
690 send_notinterested(peer, connection->mailbox);
696 void update_bitfield_blocks(peer_t peer, int index, int block_index, int block_length)
698 xbt_assert((index >= 0 && index <= FILE_PIECES), "Wrong piece.");
699 xbt_assert((block_index >= 0 && block_index <= PIECES_BLOCKS), "Wrong block : %d.", block_index);
700 for (int i = block_index; i < (block_index + block_length); i++) {
701 peer->bitfield_blocks |= (1ULL << (unsigned int)(index * PIECES_BLOCKS + i));
705 /** Returns if a peer has completed the download of a piece */
706 int piece_complete(const s_peer_t* peer, int index)
708 for (int i = 0; i < PIECES_BLOCKS; i++) {
709 if (!(peer->bitfield_blocks & 1ULL << (index * PIECES_BLOCKS + i))) {
716 /** Returns the first block that a peer doesn't have in a piece. If the peer has all blocks of the piece, returns -1. */
717 int get_first_block(const s_peer_t* peer, int piece)
719 for (int i = 0; i < PIECES_BLOCKS; i++) {
720 if (!(peer->bitfield_blocks & 1ULL << (piece * PIECES_BLOCKS + i))) {
727 /** Indicates if the remote peer has a piece not stored by the local peer */
728 int is_interested(const s_peer_t* peer, const s_connection_t* remote_peer)
730 return remote_peer->bitfield & (peer->bitfield ^ ((1 << FILE_PIECES) - 1));
733 /** Indicates if the remote peer has a piece not stored by the local peer nor requested by the local peer */
734 int is_interested_and_free(const s_peer_t* peer, const s_connection_t* remote_peer)
736 for (int i = 0; i < FILE_PIECES; i++) {
737 if (peer_has_not_piece(peer, i) && connection_has_piece(remote_peer, i) && peer_is_not_downloading_piece(peer, i)) {
744 /** Returns a piece that is partially downloaded and stored by the remote peer if any -1 otherwise. */
745 int partially_downloaded_piece(const s_peer_t* peer, const s_connection_t* remote_peer)
747 for (int i = 0; i < FILE_PIECES; i++) {
748 if (peer_has_not_piece(peer, i) && connection_has_piece(remote_peer, i) && peer_is_not_downloading_piece(peer, i) &&
749 get_first_block(peer, i) > 0)
755 /** @brief Send request messages to a peer that have unchoked us
757 * @param remote_peer peer data to the peer we want to send the request
759 void send_request_to_peer(const s_peer_t* peer, connection_t remote_peer, int piece)
761 remote_peer->current_piece = piece;
762 xbt_assert(connection_has_piece(remote_peer, piece));
763 int block_index = get_first_block(peer, piece);
764 if (block_index != -1) {
765 int block_length = MIN(BLOCKS_REQUESTED, PIECES_BLOCKS - block_index);
766 send_request(peer, remote_peer->mailbox, piece, block_index, block_length);
770 /***********************************************************
772 * Low level message functions
774 ***********************************************************/
776 /** @brief Send a "interested" message to a peer
777 * @param peer peer data
778 * @param mailbox destination mailbox
780 void send_interested(const s_peer_t* peer, const char* mailbox)
782 msg_task_t task = task_message_new(MESSAGE_INTERESTED, peer->hostname, peer->mailbox, peer->id,
783 task_message_size(MESSAGE_INTERESTED));
784 MSG_task_dsend(task, mailbox, task_message_free);
785 XBT_DEBUG("Sending INTERESTED to %s", mailbox);
788 /** @brief Send a "not interested" message to a peer
789 * @param peer peer data
790 * @param mailbox destination mailbox
792 void send_notinterested(const s_peer_t* peer, const char* mailbox)
794 msg_task_t task = task_message_new(MESSAGE_NOTINTERESTED, peer->hostname, peer->mailbox, peer->id,
795 task_message_size(MESSAGE_NOTINTERESTED));
796 MSG_task_dsend(task, mailbox, task_message_free);
797 XBT_DEBUG("Sending NOTINTERESTED to %s", mailbox);
800 /** @brief Send a handshake message to all the peers the peer has.
801 * @param peer peer data
803 void send_handshake_all(const s_peer_t* peer)
805 connection_t remote_peer;
806 xbt_dict_cursor_t cursor = NULL;
808 xbt_dict_foreach (peer->peers, cursor, key, remote_peer) {
809 msg_task_t task = task_message_new(MESSAGE_HANDSHAKE, peer->hostname, peer->mailbox, peer->id,
810 task_message_size(MESSAGE_HANDSHAKE));
811 MSG_task_dsend(task, remote_peer->mailbox, task_message_free);
812 XBT_DEBUG("Sending a HANDSHAKE to %s", remote_peer->mailbox);
816 /** @brief Send a "handshake" message to an user
817 * @param peer peer data
818 * @param mailbox mailbox where to we send the message
820 void send_handshake(const s_peer_t* peer, const char* mailbox)
822 XBT_DEBUG("Sending a HANDSHAKE to %s", mailbox);
823 msg_task_t task = task_message_new(MESSAGE_HANDSHAKE, peer->hostname, peer->mailbox, peer->id,
824 task_message_size(MESSAGE_HANDSHAKE));
825 MSG_task_dsend(task, mailbox, task_message_free);
828 /** Send a "choked" message to a peer. */
829 void send_choked(const s_peer_t* peer, const char* mailbox)
831 XBT_DEBUG("Sending a CHOKE to %s", mailbox);
833 task_message_new(MESSAGE_CHOKE, peer->hostname, peer->mailbox, peer->id, task_message_size(MESSAGE_CHOKE));
834 MSG_task_dsend(task, mailbox, task_message_free);
837 /** Send a "unchoked" message to a peer */
838 void send_unchoked(const s_peer_t* peer, const char* mailbox)
840 XBT_DEBUG("Sending a UNCHOKE to %s", mailbox);
842 task_message_new(MESSAGE_UNCHOKE, peer->hostname, peer->mailbox, peer->id, task_message_size(MESSAGE_UNCHOKE));
843 MSG_task_dsend(task, mailbox, task_message_free);
846 /** Send a "HAVE" message to all peers we are connected to */
847 void send_have(const s_peer_t* peer, int piece)
849 XBT_DEBUG("Sending HAVE message to all my peers");
850 connection_t remote_peer;
851 xbt_dict_cursor_t cursor = NULL;
853 xbt_dict_foreach (peer->peers, cursor, key, remote_peer) {
854 msg_task_t task = task_message_index_new(MESSAGE_HAVE, peer->hostname, peer->mailbox, peer->id, piece,
855 task_message_size(MESSAGE_HAVE));
856 MSG_task_dsend(task, remote_peer->mailbox, task_message_free);
860 /** @brief Send a bitfield message to all the peers the peer has.
861 * @param peer peer data
863 void send_bitfield(const s_peer_t* peer, const char* mailbox)
865 XBT_DEBUG("Sending a BITFIELD to %s", mailbox);
866 msg_task_t task = task_message_bitfield_new(peer->hostname, peer->mailbox, peer->id, peer->bitfield, FILE_PIECES);
867 MSG_task_dsend(task, mailbox, task_message_free);
870 /** Send a "request" message to a pair, containing a request for a piece */
871 void send_request(const s_peer_t* peer, const char* mailbox, int piece, int block_index, int block_length)
873 XBT_DEBUG("Sending a REQUEST to %s for piece %d (%d,%d)", mailbox, piece, block_index, block_length);
874 msg_task_t task = task_message_request_new(peer->hostname, peer->mailbox, peer->id, piece, block_index, block_length);
875 MSG_task_dsend(task, mailbox, task_message_free);
878 /** Send a "piece" message to a pair, containing a piece of the file */
879 void send_piece(const s_peer_t* peer, const char* mailbox, int piece, int block_index, int block_length)
881 XBT_DEBUG("Sending the PIECE %d (%d,%d) to %s", piece, block_index, block_length, mailbox);
882 xbt_assert(piece >= 0, "Tried to send a piece that doesn't exist.");
883 xbt_assert(!peer_has_not_piece(peer, piece), "Tried to send a piece that we doesn't have.");
885 task_message_piece_new(peer->hostname, peer->mailbox, peer->id, piece, block_index, block_length, BLOCK_SIZE);
886 MSG_task_dsend(task, mailbox, task_message_free);