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tracker.cpp
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tracker.cpp
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#include <iostream>
#include <thread>
#include <netinet/in.h>
#include <cstring>
#include <libnet.h>
#include <utility>
#include <vector>
#include <unordered_map>
#include <unordered_set>
#include "utils.h"
using namespace std;
string myIp, myPort;
// <hash, list-of-seeders-and-leechers>
unordered_map<string, unordered_set<string>> seedersAndLeechers;
void fillFieldsFromMsg(const string &msgBuffer, string &commandType, string &shaOfSha, string &clientIP,
string &clientPort) {
vector<string> tokens = getTokens(msgBuffer, FIELD_SEPARATOR);
if (tokens.empty()) {
clog << "Tokens empty" << endl;
return;
}
commandType = !tokens.empty() ? tokens[0] : "";
shaOfSha = tokens.size() > 1 ? tokens[1] : "";
clientIP = tokens.size() > 2 ? tokens[2] : "";
clientPort = tokens.size() > 3 ? tokens[3] : "";
}
void notifyOtherTracker(const string &syncMsg, const string &otherTrackerSocket) {
auto tokens = getTokens(otherTrackerSocket, ':');
int sockfd;
struct sockaddr_in servaddr{};
// Creating socket file descriptor
if ((sockfd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
printf("socket creation failed");
exit(0);
}
memset(&servaddr, 0, sizeof(servaddr));
// Filling server information
servaddr.sin_family = AF_INET;
servaddr.sin_addr.s_addr = inet_addr(tokens[0].c_str());
servaddr.sin_port = htons(stoi(tokens[1]));
// send hello message to server
sendto(sockfd, (const char *) syncMsg.c_str(), strlen(syncMsg.c_str()),
0, (const struct sockaddr *) &servaddr,
sizeof(servaddr));
}
void serveTracker(int udpfd, struct sockaddr_in cliaddr) {
char buffer[MAX_DATAGRAM_SIZE];
socklen_t addr_size = sizeof(cliaddr);
bzero(buffer, sizeof(buffer));
recvfrom(udpfd, buffer, sizeof(buffer), 0,
(struct sockaddr *) &cliaddr, &addr_size);
cout << "Incoming request over UDP from tracker: "
<< inet_ntoa(cliaddr.sin_addr) << ":" << ntohs(cliaddr.sin_port) << endl
<< "\t\t msg: " << buffer << endl;
string msgType, shaOfSha, clientIP, clientPort;
fillFieldsFromMsg(buffer, msgType, shaOfSha, clientIP, clientPort);
if (msgType == MSG_ADD) {
unordered_set<string> uset = seedersAndLeechers[shaOfSha];
uset.insert(clientIP + ":" + clientPort);
seedersAndLeechers[shaOfSha] = uset;
} else if (msgType == MSG_REMOVE) {
unordered_set<string> uset = seedersAndLeechers[shaOfSha];
uset.erase(clientIP + ":" + clientPort);
seedersAndLeechers[shaOfSha] = uset;
}
}
void serveClient(int newsocketFD, struct sockaddr_in newAddr, const string &otherTrackerSocket) {
cout << "Inside serveClient" << endl;
cout << "Received request from: "
<< inet_ntoa(newAddr.sin_addr) << ":" << ntohs(newAddr.sin_port) << endl;
int msgLength;
recv(newsocketFD, &msgLength, sizeof(msgLength), 0);
cout << "msgLength: " << msgLength << endl;
char msgBuffer[msgLength + 1];
recv(newsocketFD, msgBuffer, msgLength, 0);
msgBuffer[msgLength] = '\0';
cout << "msgBuffer: " << msgBuffer << endl;
string msgType, shaOfSha, clientIP, clientPort;
fillFieldsFromMsg(msgBuffer, msgType, shaOfSha, clientIP, clientPort);
if (msgType == MSG_ADD) {
unordered_set<string> uset = seedersAndLeechers[shaOfSha];
uset.insert(clientIP + ":" + clientPort);
seedersAndLeechers[shaOfSha] = uset;
} else if (msgType == MSG_REMOVE) {
unordered_set<string> uset = seedersAndLeechers[shaOfSha];
uset.erase(clientIP + ":" + clientPort);
seedersAndLeechers[shaOfSha] = uset;
} else if (msgType == MSG_SEEDERLIST) {
// Returns list of seedersAndLeechers for given file
unordered_set<string> uset = seedersAndLeechers[shaOfSha];
// TODO: construct a string to be returned
string response;
for (const auto &e: uset) {
response.append(e);
response += FIELD_SEPARATOR;
}
cout << "Response to be sent to client: " << response << endl;
int responseLength = response.length();
send(newsocketFD, &responseLength, sizeof(responseLength), 0);
send(newsocketFD, response.c_str(), responseLength, 0);
}
cout << "Updated seedersAndLeechers list" << endl;
for (const auto& e: seedersAndLeechers) {
cout << "\t" << e.first << endl;
for (const auto& p:e.second) {
cout << "\t\t" << p << endl;
}
cout << endl;
}
cout << "Ending connection with: "
<< inet_ntoa(newAddr.sin_addr) << ":" << ntohs(newAddr.sin_port) << endl;
close(newsocketFD);
cout << "Sending sync msg to other tracker";
if (msgType == MSG_ADD or msgType == MSG_REMOVE) {
// TODO: Notify other tracker
notifyOtherTracker(msgBuffer, otherTrackerSocket);
}
}
void tcpUdp(const string &otherTrackerSocket) {
int listenFD;
int udpFD;
int connFD;
socklen_t addr_size;
int maxfdp1;
fd_set rset;
struct sockaddr_in serveraddr{}, cliaddr{};
// Create TCP socket for listening
listenFD = socket(AF_INET, SOCK_STREAM, 0);
if (listenFD < 0) {
cerr << "Failed to create socket" << endl;
exit(1);
}
memset(&serveraddr, 0, sizeof(serveraddr));// bzero(&serveraddr, sizeof(&serveraddr))
serveraddr.sin_family = AF_INET;
serveraddr.sin_port = htons(stoi(myPort));
serveraddr.sin_addr.s_addr = inet_addr(myIp.c_str());
// binding server addr structure to listenFD
if (bind(listenFD, (struct sockaddr *) &serveraddr, sizeof(serveraddr)) < 0) {
cerr << "Error in binding to " << endl;
exit(1);
}
if (listen(listenFD, MAX_PENDING_REQUESTS) < 0) {
cerr << "Error in listen errno: " << errno << endl;
exit(1);
}
/* create UDP socket */
udpFD = socket(AF_INET, SOCK_DGRAM, 0);
// binding server addr structure to udp sockfd
bind(udpFD, (struct sockaddr *) &serveraddr, sizeof(serveraddr));
clog << "Listening on port for TCP and UDP: " << myPort << endl;
// clear the descriptor set
FD_ZERO(&rset);
// get maxfd
maxfdp1 = max(listenFD, udpFD) + 1;
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wmissing-noreturn"
while (true) {
// Infinite loop Accepts incoming requests from clients
// add listenfd and udpfd to readset
FD_SET(listenFD, &rset);
FD_SET(udpFD, &rset);
// select the ready descriptor
// select() and pselect() allow a program to monitor multiple file de‐
// scriptors, waiting until one or more of the file descriptors become
// "ready" for some class of I/O operation (e.g., input possible). A file
// descriptor is considered ready if it is possible to perform a corre‐
// sponding I/O operation
// Returns number of ready descriptors
select(maxfdp1, &rset, nullptr, nullptr, nullptr);
// if tcp socket is readable then handle
// it by accepting the connection
if (FD_ISSET(listenFD, &rset)) {
addr_size = sizeof(cliaddr);
connFD = accept(listenFD, (struct sockaddr *) &cliaddr, &addr_size);
clog << "Accepted new request " << endl;
if (connFD >= 0) {
// Process the request on separate thread
thread serveClientThread(serveClient, connFD, cliaddr, otherTrackerSocket);
serveClientThread.detach();
}
}
// if udp socket is readable receive the message.
if (FD_ISSET(udpFD, &rset)) {
addr_size = sizeof(cliaddr);
thread serverTrackersThread(serveTracker, udpFD, cliaddr);
serverTrackersThread.detach();
}
}
#pragma clang diagnostic pop
}
int main(int argc, char **argv) {
auto tokens = getTokens(argv[1], ':');
myIp = tokens[0];
myPort = tokens[1];
string otherTrackerSocket = argv[2];
thread tcpUdpThread(tcpUdp, otherTrackerSocket);
tcpUdpThread.join();
}