client.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <unistd.h>
#include <netdb.h>

void error(const char *msg) {
    perror(msg);
    exit(1);
}

int main(int argc, char *argv[]) {
    int sockfd, portno, n;
    struct sockaddr_in serv_addr;
    struct hostent *server;

    char buffer[255];

    if (argc < 3) {
        fprintf(stderr, "usage %s hostname port", argv[0]);
        exit(0);
    }

    portno = atoi(argv[2]);
    sockfd = socket(AF_INET, SOCK_STREAM, 0);

    if (sockfd < 0) 
        fprintf(stderr, "ERROR opening socket");
        

    server = gethostbyname(argv[1]);
    if (server == NULL) {
        fprintf(stderr, "ERROR no such host");
    }

    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("Connection Failed");

    while(1) {
        bzero(buffer, 255);
        printf("Client: ");
        fgets(buffer, 255, stdin);
        n = write(sockfd, buffer, strlen(buffer));

        if (n < 0)
            error("ERROR on writing");

        bzero(buffer, 255);
        n = read(sockfd, buffer, 255);
        if (n < 0) 
            error("ERROR on reading");
        
        printf("Server: %s", buffer);

        int i = strncmp("Bye", buffer, 3);
        if (i == 0)
            break;
    }

    close(sockfd);
    return 0;
}