ComputerNetworksAndSecurity/Codes/Code-A4 (Sliding Window).cpp

#include <iostream>
#include <vector>
#include <queue>
using namespace std;

class SlidingWindow {
private:
  int window_size;
  int total_frames;
  vector<int> sent_frames; // queue of sent frames
  int next_frame_to_send; // index of the next frame to send
  int next_frame_to_receive; // index of the next frame to receive

public:
  SlidingWindow(int window_size, int total_frames) {
    this->window_size = window_size;
    this->total_frames = total_frames;
    this->next_frame_to_send = 0;
    this->next_frame_to_receive = 0;
  }

  // send a frame
  void send_frame() {
    if (sent_frames.size() < window_size && next_frame_to_send < total_frames) {
      sent_frames.push_back(next_frame_to_send);
      next_frame_to_send++;
      cout<<"Sent frame "<<sent_frames.back()<<endl;
      }
    else {
      cout<<"Window is full. Waiting before sending next frames."<<endl;
    }
  }

  // receive a frame
  void receive_frame(int frame_number) {
    if (frame_number == next_frame_to_receive) {
      next_frame_to_receive++;
      cout<<"Received frame "<<frame_number<<endl;
    }
    else {
      cout<<"Received frame "<<frame_number<<", but expected frame "<<next_frame_to_receive<<endl;
    }
    // remove acknowledged frames from the sent_frames queue
    while (!sent_frames.empty() && sent_frames.front()<=next_frame_to_receive-1) {
      sent_frames.erase(sent_frames.begin());
    }
  }

  bool all_frames_sent() {
    return next_frame_to_send == total_frames;
  }

  bool all_frames_received() {
    return next_frame_to_receive == total_frames;
  }
};

int main() {
    int window_size, total_frames;
    cout << "Enter the window size:\t";
    cin >> window_size;
    cout << "Enter the total number of frames:\t";
    cin >> total_frames;

    SlidingWindow window(window_size, total_frames);

    while (!window.all_frames_sent() || !window.all_frames_received()) {
        window.send_frame();
        // simulate receiving frames
        for (int i=0; i<rand()%3; i++) {
            int frame_number = rand() % total_frames;
            window.receive_frame(frame_number);
        }
    }
    cout<<"All frames sent and received successfully!"<<endl;

    return 0;
}