Client

#include <array>
#include <chrono>
#include <fstream>
#include <iostream>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <netdb.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <unistd.h>

void error(const char *msg)
{
    perror(msg);
    exit(0);
}

int main(int argc, char *argv[])
{

    int sockfd, portno, n;
    struct sockaddr_in serv_addr;
    struct hostent *server;

    double dbuffer[1]={0.0};

// Measured RTT will be written to a csv file

    std::array<std::chrono::high_resolution_clock::time_point, 2> timer;
    std::chrono::duration<double, std::milli> tdiff_ms;

    if (argc < 3) {
    fprintf(stderr,"usage %s hostname port\n", argv[0]);
    exit(0);
    }
    portno = atoi(argv[2]);
    // Create socket. At this point we can directly set the DSCP value
    sockfd = socket(AF_INET, SOCK_STREAM, 0);

//  int priority = 192; //110 000 - voice
//  if(setsockopt(sockfd, IPPROTO_IP, IP_TOS, &priority, sizeof(priority)) < 0)
//  {
//      printf("Priority could not be set\n");
//  }

    if (sockfd < 0)
        error("ERROR opening socket");
    server = gethostbyname(argv[1]);

    if (server == NULL)
    {
        fprintf(stderr,"ERROR, no such host\n");
        exit(0);
    }

    bzero((char *) &serv_addr, sizeof(serv_addr));
    serv_addr.sin_family = AF_INET;
    bcopy((char *)server->h_addr, (char *)&serv_addr.sin_addr.s_addr, server->h_length);
    serv_addr.sin_port = htons(portno);

    if (connect(sockfd, (struct sockaddr *) &serv_addr, sizeof(serv_addr)) < 0)
        error("ERROR connecting");

    printf("Start sending messages..\n");

    std::ofstream outputFile("RTT.csv");

    do
    {
        dbuffer[0]++;

        timer[0] = std::chrono::high_resolution_clock::now(); // start

        printf("Sending %f to server.\n", dbuffer[0]);
        n = write(sockfd, dbuffer, sizeof(dbuffer));

        if (n < 0)
            error("ERROR writing to socket");

        n = read(sockfd, dbuffer, sizeof(dbuffer));
        printf("Got %f from server.\n", dbuffer[0]);

        timer[1] = std::chrono::high_resolution_clock::now(); // stop
        tdiff_ms = timer[1] - timer[0];
        std::cout << "Time to get message back : " << tdiff_ms.count() << " ms." << std::endl;

        // Save measured RTT to file
        outputFile << tdiff_ms.count() << ",";

        if (n < 0)
            error("ERROR reading from socket");
    }
    while (dbuffer[0] < 2000);

    outputFile.close();
    close(sockfd);

    return 0;
}