task1.c

/*
# Copyright 2025 University of Kentucky
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
# SPDX-License-Identifier: Apache-2.0
*/

/* 
Please specify the group members here

# Student #1: Charles Schmidt

*/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <sys/epoll.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <pthread.h>
#include <limits.h>

#define MAX_EVENTS 64
#define MESSAGE_SIZE 16
#define DEFAULT_CLIENT_THREADS 4
#define EPOLL_SAMPLING_RATE 100
#define TIMEOUT 1000
#define NUM_PIPE_PACKETS 5

char *server_ip = "127.0.0.1";
int server_port = 12345;
char *client_ip;
int client_port = 8080;
int num_client_threads = DEFAULT_CLIENT_THREADS;
int num_requests = 1000000;
socklen_t addr_len = sizeof(struct sockaddr_in);

typedef struct {
    int epoll_fd;
    int socket_fd;
    int tx;
    int rx;
    char thread_num;
    long long total_rtt;
    long total_messages;
    float request_rate;
    struct sockaddr_in server_addr;
} client_thread_data_t;

void *client_thread_func(void *arg) {
    client_thread_data_t *data = (client_thread_data_t *)arg;
    struct epoll_event event, events[MAX_EVENTS];
    char send_buf[MESSAGE_SIZE] = "ABCDEFGHIJKMLNOP";
    char recv_buf[MESSAGE_SIZE];
    struct timeval start, end, cur;
    struct timeval timer_array[NUM_PIPE_PACKETS];
    int sent_array[NUM_PIPE_PACKETS];
    


    data->request_rate = 0;
    data->total_rtt = 0;
    data->total_messages = 0;

    // Register the socket in the epoll instance
    event.events = EPOLLIN;
    event.data.fd = data->socket_fd;
    epoll_ctl(data->epoll_fd, EPOLL_CTL_ADD, data->socket_fd, &event);
    for(char i=0;i<NUM_PIPE_PACKETS;i++){
        send_buf[0] = i;
        send_buf[1] = data->thread_num;
        data->tx++;
        send(data->socket_fd, send_buf, MESSAGE_SIZE, 0);
        sent_array[i] = 1;
        gettimeofday(&timer_array[i], NULL);
    }

    while (1) {
        if(data->tx < num_requests){
          for(char i=0;i<NUM_PIPE_PACKETS;i++){
            gettimeofday(&cur,NULL);
            long long micro = (cur.tv_sec - timer_array[i].tv_sec) * 1000000LL + (cur.tv_usec - timer_array[i].tv_usec);
            if((micro/1000 > TIMEOUT||!sent_array[i])&&data->tx < num_requests){
              gettimeofday(&timer_array[i],NULL);
              send_buf[0] = i;
              send_buf[1] = data->thread_num;
              if(send(data->socket_fd, send_buf, MESSAGE_SIZE, 0)<0){
                perror("timeout sendto failure");
              }
              sent_array[i] = 1;
              data->tx++;
            }
          }
        }
        // use a low timeout for the epoll wait so that the function can keep checking the individual
        // packets timers like a sampling rate 
        int n_events = epoll_wait(data->epoll_fd, events, MAX_EVENTS, EPOLL_SAMPLING_RATE);
        for (int i = 0; i < n_events; i++) {
            if (events[i].data.fd == data->socket_fd) {
                
                int n = recv(data->socket_fd, recv_buf, MESSAGE_SIZE,0);
                if(n<0){
                  perror("ack recieve failed");
                }
                char index = recv_buf[0];
                sent_array[index] = 0;
                gettimeofday(&timer_array[index],NULL);
                data->rx++;
                

                // Calculate RTT
            }
        }
        gettimeofday(&end, NULL);
        long long rtt = (end.tv_sec - cur.tv_sec) * 1000000LL + (end.tv_usec - cur.tv_usec);
        if(data->tx >= num_requests && rtt/1000 >= TIMEOUT) break;
      
    }

    // Update request rate

    // printf("Total RTT: %lld s\n", data->total_rtt / 1000000);
    // printf("Total messages: %ld\n", data->total_messages);
    // printf("RPS: %f\n", data->request_rate);

    close(data->socket_fd);
    close(data->epoll_fd);
    return NULL;
}

void run_client() {
    pthread_t threads[num_client_threads];
    client_thread_data_t thread_data[num_client_threads];
    struct sockaddr_in server_addr,client_addr;

    memset(&server_addr, 0, sizeof(server_addr));
    server_addr.sin_family = AF_INET;
    server_addr.sin_port = htons(server_port);
    if(inet_pton(AF_INET, server_ip, &server_addr.sin_addr)<0){
      perror("bad server ip");
    }

    // Create client threads
    for (int i = 0; i < num_client_threads; i++) {
        thread_data[i].epoll_fd = epoll_create1(0);
        thread_data[i].socket_fd = socket(AF_INET,SOCK_DGRAM,0);
        thread_data[i].server_addr = server_addr;
        thread_data[i].tx = 0;
        thread_data[i].rx = 0;
        thread_data[i].thread_num = i;
        if(connect(thread_data[i].socket_fd,(struct sockaddr *)&server_addr,addr_len)<0){
          perror("client socket failed to connect");
        }
    }

    for (int i = 0; i < num_client_threads; i++) {
        pthread_create(&threads[i], NULL, client_thread_func, &thread_data[i]);
    }

    // Wait for threads to complete
    long long total_rtt = 0;
    long total_messages = 0;
    float total_request_rate = 0;
    double tx = 0.0;
    double rx = 0.0;
    for (int i = 0; i < num_client_threads; i++) {
        pthread_join(threads[i], NULL);
        total_rtt += thread_data[i].total_rtt;
        total_messages += thread_data[i].total_messages;
        total_request_rate += thread_data[i].request_rate;
        tx += thread_data[i].tx;
        rx += thread_data[i].rx;
    }
    printf("tx: %i\n",(int)tx);
    printf("rx: %i\n",(int)rx);
    printf("percentage packets loss: %f\n",1-(rx/tx));
}

void run_server() {
    int server_fd = socket(AF_INET, SOCK_DGRAM, 0);
    struct sockaddr_in server_addr,client_addr;
    memset(&server_addr, 0, sizeof(server_addr));
    server_addr.sin_family = AF_INET;
    server_addr.sin_addr.s_addr = INADDR_ANY;
    server_addr.sin_port = htons(server_port);

    if(bind(server_fd,(struct sockaddr *)&server_addr,addr_len)<0){
      perror("server port failed to bind");
    }
    
    int epoll_fd = epoll_create1(0);
    if(epoll_fd<0){
      perror("epoll create failed");
    }
    struct epoll_event event, events[MAX_EVENTS];

    event.events = EPOLLIN;
    event.data.fd = server_fd;
    if(epoll_ctl(epoll_fd, EPOLL_CTL_ADD, server_fd, &event)<0){
      perror("epoll ctl failed");
    } 
    
    while (1) {
        int n_events = epoll_wait(epoll_fd, events, MAX_EVENTS, TIMEOUT);
        if(n_events<0){
          perror("epoll wait failed");
        }
        for (int i = 0; i < n_events; i++) {
            if (events[i].data.fd == server_fd) {
                // Handle client data
                char buffer[MESSAGE_SIZE];
                int n = recvfrom(server_fd, &buffer, MESSAGE_SIZE, 0,(struct sockaddr *)&client_addr,&addr_len);
                if(n == -1){
                  perror("packet error");
                }
                if(sendto(server_fd, &buffer, MESSAGE_SIZE, 0,(struct sockaddr *)&client_addr,addr_len)<0){
                  perror("server send failed");
                }
            }
        }
    }

    close(server_fd);
    close(epoll_fd);
}

int main(int argc, char *argv[]) {
    if (argc > 1 && strcmp(argv[1], "server") == 0) {
        if (argc > 2) server_ip = argv[2];
        if (argc > 3) server_port = atoi(argv[3]);

        run_server();
    } else if (argc > 1 && strcmp(argv[1], "client") == 0) {
        if (argc > 2) server_ip = argv[2];
        if (argc > 3) server_port = atoi(argv[3]);
        if (argc > 4) num_client_threads = atoi(argv[4]);
        if (argc > 5) num_requests = atoi(argv[5]);
       

        run_client();
    } else {
        printf("Usage: %s <server|client> [server_ip server_port num_client_threads num_requests]\n", argv[0]);
    }

    return 0;
}