client.c

#include<stdio.h>
#include<stdlib.h>
#include<unistd.h>
#include<string.h>
#include<sys/types.h>
#include<sys/socket.h>
#include<netinet/in.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\n", argv[0]);
        exit(1);
    }
    portno = atoi(argv[2]);
    sockfd = socket(AF_INET, SOCK_STREAM, 0);
    if(sockfd < 0)
        error("Error opening socket");
   server = gethostbyname(argv[1]);
    if(server == NULL){
        fprintf(stderr, "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);
        fgets(buffer, 255, stdin);
        n = write(sockfd, buffer, strlen(buffer));
        if(n < 0){
            error("Error while writing");
        }
    bzero(buffer , 255);
    n = read(sockfd, buffer, 255);
    if(n < 0)
        error("Error on reading");

    printf("Server: %s", buffer);

    int i = strncmp("sayonara", buffer, 8);
    int j = strncmp("Sayonara", buffer, 8);
    if(i == 0 || j == 0)
        break;
    }
    close(sockfd);
    return 0;

}