void start_peers() {
CURL *curl;
CURLcode res;
curl = curl_easy_init();
{
int bytes_left = 0;
bytes_left = missing_blocks() * piece_length;
if(piece_status[get_total_pieces_available()-1] == PIECE_EMPTY){
bytes_left -= piece_length;
bytes_left += file_length%piece_length;
}
printf("Announce URL: %s\n",announce_url);
}
if(curl) {
curl_easy_setopt(curl, CURLOPT_URL, announce_url);
curl_easy_setopt(curl, CURLOPT_TIMEOUT, 1);
curl_easy_setopt(curl, CURLOPT_NOSIGNAL, 1);
curl_easy_setopt(curl, CURLOPT_CONNECTTIMEOUT, 1);
FILE *anno = fopen("/tmp/anno.tmp","w+");
if(!anno) {
perror("couldn't create temporary file\n");
}
int attempts=0;
curl_easy_setopt(curl, CURLOPT_WRITEDATA, anno);
while((res = curl_easy_perform(curl)) !=CURLE_OK &&
attempts < 5) {
fprintf(stderr, "curl_easy_perform() failed: %s\n",
curl_easy_strerror(res));
attempts++;
}
fclose(anno);
if (attempts<5) {
struct stat anno_stat;
if(stat("/tmp/anno.tmp",&anno_stat)) {
perror("couldn't stat /tmp/anno.tmp");
exit(1);
}
// the announcement document is in /tmp/anno.tmp.
// so map that into memory, then call handle_announcement on the returned pointer
handle_announcement(mmap(0,anno_stat.st_size,PROT_READ,MAP_SHARED,open("/tmp/anno.tmp",O_RDONLY),0),anno_stat.st_size);
}
curl_easy_cleanup(curl);
}
}
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;
}
int main(int argc, char** argv) {
if(argc<2) {
fprintf(stderr,"Usage: ./hw4 <torrent file>\n");
exit(1);
}
setvbuf(stdout,screenbuf,_IOFBF,10000);
// create a global peer_id for this session. Every peer_id should include -OBCS342-.
for(int i=strlen(peer_id);i<20;i++)
peer_id[i]='0'+random()%('Z'-'0'); // random numbers/letters between 0 and Z
// make sure the torrent file exists
struct stat file_stat;
if(stat(argv[1],&file_stat)) {
perror("Error opening file.");
exit(1);
}
// map .torrent file into memory, and parse contents
int fd = open(argv[1],O_RDONLY);
char *buf = mmap(0,file_stat.st_size,PROT_READ,MAP_SHARED,fd,0);
if(buf==(void*)-1) {
perror("couldn't mmap file");
exit(1);
}
size_t off = 0;
int error = 0;
torrent = (struct bencode_dict*)ben_decode2(buf,file_stat.st_size,&off,&error);
if(!torrent) {
printf("Got error %d, perhaps a malformed torrent file?\n",error);
exit(1);
}
// pull out the .info part, which has stuff about the file we're downloading
info = (struct bencode*)ben_dict_get_by_str((struct bencode*)torrent,"info");
struct bencode_list* files = (struct bencode_list*)ben_dict_get_by_str(info,"files");
// multi-file case
if(files) {
for(int i=0;i<files->n;i++) {
struct bencode* file = files->values[i];
struct bencode_list* path = (struct bencode_list*)ben_dict_get_by_str(file,"path");
printf("Filename %s/%s\n",((struct bencode_str*)ben_dict_get_by_str(info,"name"))->s,((struct bencode_str*)path->values[0])->s);
// accumulate a total length so we know how many pieces there are
file_length+=((struct bencode_int*)ben_dict_get_by_str(file,"length"))->ll;
}
}
// single-file case
else {
struct bencode_str* name = (struct bencode_str*)ben_dict_get_by_str(info,"name");
if(name) {
file_length = ((struct bencode_int*)ben_dict_get_by_str(info,"length"))->ll;
}
}
fflush(stdout);
piece_length = ((struct bencode_int*)ben_dict_get_by_str(info,"piece length"))->ll;
// create our output file, and set up a piece_status array
piece_status = calloc(1,sizeof(int)*(int)(file_length/piece_length+1)); //start with an empty bitfield
/* compute the message digest and info_hash from the "info" field in the torrent */
size_t len;
char info_hash[100];
char* encoded = ben_encode(&len,(struct bencode*)info);
SHA1(encoded,len,digest); // digest is a global that holds the raw 20 bytes
// info_hash is a stringified version of the digest, for use in the announce URL
memset(info_hash,0,100);
for(int i=0;i<20;i++)
sprintf(info_hash+3*i,"%%%02x",digest[i]);
// compile a suitable announce URL for our document
sprintf(announce_url,"%s?info_hash=%s&peer_id=%s&port=6881&left=%d",((struct bencode_str*)ben_dict_get_by_str((struct bencode*)torrent,"announce"))->s,info_hash,peer_id,file_length);
printf("Announce URL: %s\n",announce_url);
fflush(stdout);
start_peers();
// now benPeers has the peers list from handle_announcement; let's handle this
// handle the binary case
FD_ZERO(&readset);
FD_ZERO(&writeset); // zero out the sets before adding things to them
if(benPeers->type == BENCODE_STR) {
printf("Got binary list of peers\n");
// replace all occurrences of pa with peerlist[i]
struct peer_addr *peerlist = (struct peer_addr*)((struct bencode_str*)benPeers)->s;
for(int i=0;i<((struct bencode_str*)benPeers)->len/6;i++) {
struct in_addr a;
a.s_addr = peerlist[i].addr;
printf("Found peer %s:%d\n",inet_ntoa(a),ntohs(peerlist[i].port));
fprintf(stderr,"Connecting...\n");
struct peer_addr* peeraddr = (struct peer_addr*)&peerlist[i];
if(peer_connected(peeraddr->addr)) {
fprintf(stderr,"Already connected\n");
} else {
// open the socket
int s = socket(AF_INET, SOCK_STREAM,0);
if(s < 0){
perror("Error creating socket: ");
}
struct sockaddr_in addr;
addr.sin_family = AF_INET;
addr.sin_addr.s_addr = peeraddr->addr;
addr.sin_port = peeraddr->port;
// set up the timeout
struct timeval tv;
tv.tv_sec = 60;
if(setsockopt(s,SOL_SOCKET,SO_RCVTIMEO, (char *)&tv, sizeof tv))
perror("setsockopt");
int res = connect(s, (struct sockaddr*)&addr, sizeof(addr));
if(res == -1) {
fprintf(stderr,"Couldn't connect to %d \n", peeraddr->port);
fflush(stderr);
perror("Error while connecting: ");
} else {
printf("Connected!\n"); // for debugging purposes
// register the new peer in our list of peers
struct peer_state* peer = calloc(1,sizeof(struct peer_state));
peer->socket = s; // socket is current socket
peer->ip= peeraddr->addr; // address is the address of the current peer
peer->next = peers; // stick it at the front of the linked list
peer->connected = 0; // we're not connected until we've done handshaking
peer->choked = 1;
peer->incoming = malloc(BUFSIZE);
peer->bitfield = calloc(1,file_length/piece_length/8+1); // start with an empty bitfield
peers = peer; // make me the head of the LL
char protocol[] = "BitTorrent protocol";
unsigned char pstrlen = strlen(protocol);
unsigned char msg[pstrlen+49];
msg[0] = pstrlen;
memcpy(msg+1,protocol,pstrlen);
memcpy(msg+1+pstrlen+8,digest,20);
memcpy(msg+1+pstrlen+8+20,peer_id,20);
// put handshaking msg into all peers' outgoing
peer->outgoing_count = 0;
peer->outgoing = malloc(BUFSIZE);
memcpy(peer->outgoing+peer->outgoing_count, msg, sizeof msg);
peer->outgoing_count += sizeof msg;
FD_SET(s, &readset); // add s (fd of peer's socket) to the read and write sets
FD_SET(s, &writeset);
}
}
}
}
// handle the bencoded case
else {
for(int i=0;i<benPeers->n;i++) {
printf("Got bencoded list of peers\n");
struct bencode *peer = benPeers->values[i];
char *address = ((struct bencode_str*)ben_dict_get_by_str(peer,"ip"))->s;
unsigned short port = ((struct bencode_int*)ben_dict_get_by_str(peer,"port"))->ll;
printf("Found peer %s:%d\n",address,port);
fprintf(stderr,"Connecting...\n");
struct peer_addr *peeraddr = malloc(sizeof(struct peer_addr));
peeraddr->addr=inet_addr(address);
peeraddr->port=htons(port);
if(peer_connected(peeraddr->addr)) {
fprintf(stderr,"Already connected\n");
} else {
// open the socket
int s = socket(AF_INET, SOCK_STREAM,0);
if(s < 0){
perror("Error creating socket: ");
}
struct sockaddr_in addr;
addr.sin_family = AF_INET;
addr.sin_addr.s_addr = peeraddr->addr;
addr.sin_port = peeraddr->port;
// set up the timeout
struct timeval tv;
tv.tv_sec = 60;
if(setsockopt(s,SOL_SOCKET,SO_RCVTIMEO, (char *)&tv, sizeof tv))
perror("setsockopt");
// in a more ideal world, this would break out of the current iteration of the loop
int res = connect(s, (struct sockaddr*)&addr, sizeof(addr));
if(res == -1) {
fprintf(stderr,"Couldn't connect to %d \n", peeraddr->port);
fflush(stderr);
perror("Error while connecting: ");
} else {
printf("Connected!\n"); // for debugging purposes
// register the new peer in our list of peers
struct peer_state* peer = calloc(1,sizeof(struct peer_state));
peer->socket = s; // socket is current socket
peer->ip= peeraddr->addr; // address is the address of the current peer
peer->next = peers; // stick it at the front of the linked list
peer->connected = 0; // we're not connected until we've done handshaking
peer->choked = 1;
peer->incoming = malloc(BUFSIZE);
peer->bitfield = calloc(1,file_length/piece_length/8+1); // start with an empty bitfield
peers = peer; // make me the head of the LL
char protocol[] = "BitTorrent protocol";
unsigned char pstrlen = strlen(protocol);
unsigned char msg[pstrlen+49];
msg[0] = pstrlen;
memcpy(msg+1,protocol,pstrlen);
memcpy(msg+1+pstrlen+8,digest,20);
memcpy(msg+1+pstrlen+8+20,peer_id,20);
// put handshaking msg into all peers' outgoing
peer->outgoing_count = 0;
peer->outgoing = malloc(BUFSIZE);
memcpy(peer->outgoing+peer->outgoing_count, msg, sizeof msg);
peer->outgoing_count += sizeof msg;
FD_SET(s, &readset); // add s (fd of peer's socket) to the read and write sets
FD_SET(s, &writeset);
}
}
}
}
while(1) {
fd_set rtemp, wtemp;
FD_ZERO(&rtemp);
FD_ZERO(&wtemp); // zero out the temp sets
memcpy(&rtemp, &readset, sizeof readset);
memcpy(&wtemp, &writeset, sizeof writeset);
// timeout for the select call? probably too high
struct timeval tv;
tv.tv_sec = 0;
int selected = select(FD_SETSIZE, &rtemp, &wtemp, NULL, &tv);
struct peer_state* peerTemp = peers;
while(peerTemp) {
//printf("Current peer name is %s\n", inet_ntoa(*(struct in_addr *)&peerTemp->ip));
if(FD_ISSET(peerTemp->socket,&rtemp)) { // if we're reading
if(!peerTemp->connected) {
recv_handshake(peerTemp); // can all receive at once? or not?
FD_SET(peerTemp->socket, &readset);
} else {
int ret = receive_message(peerTemp); // we can just use the current receive_message fcn
if(ret == 2) {
handle_message(peerTemp);
} // else just keep on chuggin
}
//FD_SET(peerTemp->socket, &readset); // then add it to the readset, always
}
if(FD_ISSET(peerTemp->socket,&wtemp)) { // if we're writing
send_message(peerTemp);
}
peerTemp = peerTemp->next;
}
// if we don't have any missing blocks, breeaaaakk
if(missing_blocks() == 0)
break;
}
}