bool Downloader::request_one() {
log_->trace() << log_tag() << BOOST_CURRENT_FUNCTION;
// Try to choose block to request
for(auto& needed_chunk : needed_chunks_) {
auto& ct_hash = needed_chunk.first;
// Try to choose a remote to request this block from
auto remote = find_node_for_request(ct_hash);
if(remote == nullptr) continue;
// Rebuild request map to determine, which block to download now.
AvailabilityMap<uint32_t> request_map = needed_chunk.second->file_map();
for(auto& request : needed_chunk.second->requests)
request_map.insert({request.second.offset, request.second.size});
// Request, actually
if(!request_map.full()) {
NeededChunk::BlockRequest request;
request.offset = request_map.begin()->first;
request.size = std::min(request_map.begin()->second, uint32_t(Config::get()->globals()["p2p_block_size"].asUInt()));
request.started = std::chrono::steady_clock::now();
remote->request_block(ct_hash, request.offset, request.size);
needed_chunk.second->requests.insert({remote, request});
return true;
}
}
return false;
}
void call()
{
int i=0;
for(i;i<3;i++)
{
request_block();
}
}
void listen_from_peers()
{
struct peer_state* peer = peers;
unsigned int msglen = 0;
while(missing_blocks() > 0)
{
fd_set fdrset_clone;
fd_set fdwset_clone;
FD_COPY(&fdrset,&fdrset_clone);
FD_COPY(&fdwset,&fdwset_clone);
int rdy = select(FD_SETSIZE,&fdrset_clone,&fdwset_clone,0, 0);
if(rdy <= 0) {
continue;
}
peer = peers;
if(active_peers() == 0){
break;
}
while(peer){
if(FD_ISSET(peer->socket,&fdwset_clone)){
if(peer->connected == 0){
//to send the handshake if it is not connected
send_handshake(peer);
}
else if(peer->send_count > 0) {
//to send the have/interested/piece messages to peers
send_buffed_msg(peer);
}
}
if(FD_ISSET(peer->socket,&fdrset_clone))
{
int newbytes = recv(peer->socket,peer->incoming+peer->count,BUFSIZE-peer->count,0);
if(newbytes <= 0){
peer->trying_to_connect = 0;
if(newbytes == 0){
piece_status[peer->requested_piece] = PIECE_EMPTY;
}
disconnet_peer(peer);
reconnect_peer(peer);
peer = peer->next;
continue;
}
peer->count += newbytes;
if(!peer->handshaked){
peer->count -= peer->incoming[0]+49;
if(peer->count) {
memmove(peer->incoming,peer->incoming + peer->incoming[0]+49,peer->count);
}
peer->handshaked = 1;
}
if(memcmp(peer->incoming+peer->incoming[0]+8+20,"-UICCS450-",strlen("-UICCS450-"))==0) {
fprintf(stderr,"Caught a CS450 peer, exiting.\n");
disconnet_peer(peer);
continue;
}
while(peer->count >= (ntohl(((int*)peer->incoming)[0])) + 4){
msglen = ntohl(((int*)peer->incoming)[0]);
switch(peer->incoming[4]) {
// CHOKE
case 0: {
if(debug)
fprintf(stderr,"Choke\n");
peer->choked = 1;
piece_status[peer->requested_piece]=PIECE_EMPTY;
peer->requested_piece = -1;
break;
}
// UNCHOKE
case 1: {
if(debug)
fprintf(stderr,"Unchoke\n");
peer->choked = 0;
peer->requested_piece = next_piece(-1,peer);
request_block(peer,peer->requested_piece,0);
break;
}
//Interested
case 2: {
//dev_notifier();
send_choke_unchoke_msg(peer,0); //ischoked = 0
peer->not_interested = 0;
break;
}
//Not interested
case 3: {
//dev_notifier();
peer->not_interested = 1;
break;
}
// HAVE -- update the bitfield for this peer
case 4: {
int piece = ntohl(*((int*)&peer->incoming[5]));
int bitfield_byte = piece/8;
int bitfield_bit = piece%8;
if(debug)
fprintf(stderr,"Have %d\n",piece);
peer->bitfield[bitfield_byte] |= 1 << (7 - bitfield_bit);
piece_occurence_value[piece]++;
send_interested(peer);
break;
}
// BITFIELD -- set the bitfield for this peer
case 5:
//peer->choked = 0; //commenting it according to prof's note in class
if(debug)
printf("Bitfield of length %d\n",msglen-1);
int fieldlen = msglen - 1;
if(fieldlen != (file_length/piece_length/8+1)) {
disconnet_peer(peer);
if(active_peers() == 0){
break;
}
peer = peer->next;
continue;
}
memcpy(peer->bitfield,peer->incoming+5,fieldlen);
read_bit_maps(peer->bitfield,fieldlen);
send_interested(peer);
break;
//Request piece
case 6: {
if(peer->i_choked_it == 1)
break;
decode_request_send_piece_to_peer(peer);
}
break;
// PIECE
case 7: {
//make the tit for tatter
peer->send_recv_balancer++;
if(peer->i_choked_it && peer->send_recv_balancer == 0){
peer->i_choked_it = 0;
send_choke_unchoke_msg(peer,0); //unchoke peer
}
int piece = ntohl(*((int*)&peer->incoming[5]));
int offset = ntohl(*((int*)&peer->incoming[9]));
int datalen = msglen - 9;
fprintf(stderr,"Writing piece %d, offset %d, ending at %d\n",piece,offset,piece*piece_length+offset+datalen);
write_block(peer->incoming+13,piece,offset,datalen,1);
draw_state();
offset+=datalen;
if(offset==piece_length || (piece*piece_length+offset == file_length) ) {
broadcast_have_msg(piece);
draw_state();
if(debug)
fprintf(stderr,"Reached end of piece %d at offset %d\n",piece,offset);
peer->requested_piece=next_piece(piece,peer);
offset = 0;
}
request_block(peer,peer->requested_piece,offset);
break;
}
}
drop_message(peer);
}
}
peer = peer->next;
}
}
return;
}
// handles the message. no, we *don't* need to pass in msglen
int handle_message(struct peer_state* peer) {
int msglen = ntohl(((int*)peer->incoming)[0]); // because not returned from receive message
int newbytes = 0;
fflush(stdout);
if(msglen == 0) {
piece_status[peer->requested_piece] = PIECE_EMPTY;
draw_state();
shutdown_peer(peer);
return 0;
}
// not picking any of the cases in switch; calling handle_message prematurely?
switch(peer->incoming[4]) {
// CHOKE
case 0: {
if(debug)
fprintf(stderr,"Choke\n");
peer->choked = 1;
piece_status[peer->requested_piece] = PIECE_EMPTY;
peer->requested_piece = -1;
break;
}
// UNCHOKE
case 1: {
if(debug)
fprintf(stderr,"Unchoke\n");
peer->choked = 0;
// grab a new piece - WARNING: this assumes that you don't get choked mid-piece!
peer->requested_piece = next_piece(-1);
// keep track of how many bytes downloaded of the piece
// add to piece_status
request_block(peer,peer->requested_piece,0);
break;
}
// INTERESTED
case 2: {
// TODO: Send unchoke message to peer (?)
peer->choked = 0; // unchoke peer
break;
}
// HAVE -- update the bitfield for this peer
case 4: {
int piece_index = ntohl(*((int*)&peer->incoming[5]));
int bitfield_byte = piece_index/8;
int bitfield_bit = 7-(piece_index%8);
if(debug)
fprintf(stderr,"Have %d\n", piece_index);
peer->bitfield[bitfield_byte] |= 1 << bitfield_bit;
send_interested(peer);
break;
}
// BITFIELD - set the bitfield for this peer
case 5: {
peer->choked = 0;
if(debug)
printf("Bitfield of length %d\n", msglen-1);
int fieldlen = msglen - 1;
if(fieldlen != (file_length/piece_length/8+1)) {
fprintf(stderr,"Incorrect bitfield size, expected %d\n", file_length/piece_length/8+1);
shutdown_peer(peer);
return 0;
}
memcpy(peer->bitfield,peer->incoming+5,fieldlen);
send_interested(peer);
break;
}
// REQUEST
case 6: {
// peer is requesting piece
// copy from file
// send to them
// update ratio information
break;
}
// PIECE
case 7: {
int piece = ntohl(*((int*)&peer->incoming[5]));
int offset = ntohl(*((int*)&peer->incoming[9]));
int datalen = msglen - 9;
fprintf(stderr,"Writing piece %d, offset %d, ending at %d\n", piece, offset, piece*piece_length+offset+datalen);
write_block(peer->incoming+13,piece,offset,datalen,1); // save this block to comp
draw_state(); // segfault source?
offset += datalen;
if(offset==piece_length || (piece*piece_length+offset == file_length) ) {
if(debug)
fprintf(stderr, "Reached end of piece %d at offset %d\n", piece, offset);
peer->requested_piece = next_piece(piece);
offset = 0;
if(peer->requested_piece == -1) {
fprintf(stderr,"No more pieces to download!\n");
// but don't exit if sth. is still being downloaded
for(int i = 0; i < file_length/piece_length+1; i++)
if(piece_status[i] != 2) {
shutdown_peer(peer);
return 0;
}
shutdown_peer(peer);
return 0;
}
}
request_block(peer,peer->requested_piece,offset);
break;
}
case 20: {
printf("Extended type is %d\n", peer->incoming[5]);
struct bencode *extended = ben_decode(peer->incoming,msglen);
print_bencode(extended);
break;
}
}
drop_message(peer);
return 1;
}