POSIX Sockets TCP Daytime Client


Example

This is a TCP daytime client kept as simple as possible.

#include <unistd.h>      /* unix standard library */
#include <arpa/inet.h>   /* IP addresses manipulation utilities */
#include <netinet/in.h>  /* sockaddr_in structure definition */
#include <sys/socket.h>  /* berkley socket library */
#include <stdio.h>       /* standard I/O library */
#include <string.h>      /* include to have memset*/
#include <stdlib.h>      /* include to have exit*/

#define MAXLINE 1024

int main(int argc, char *argv[])
{
    int sock_fd;
    int nread;
    struct sockaddr_in serv_add;
    char buffer[MAXLINE];

    /* socket creation third parameter should be IPPROTO_TCP but 0 is an
     * accepted value*/
    sock_fd = socket(AF_INET, SOCK_STREAM, 0);

    /* address initialization */
    memset(&serv_add, 0, sizeof(serv_add));     /* init the server address */
    serv_add.sin_family = AF_INET;              /* address type is IPV4 */
    serv_add.sin_port = htons(13);              /* daytime post is 13 */

    /* using inet_pton to build address */
    inet_pton(AF_INET, argv[1], &serv_add.sin_addr);

    /* connect to the server */
    connect(sock_fd, (struct sockaddr *)&serv_add, sizeof(serv_add));

    /* read daytime from server */
    while ((nread = read(sock_fd, buffer, MAXLINE)) > 0)
    {
        buffer[nread] = 0;
        if (fputs(buffer, stdout) == EOF)
        {
            perror("fputs error"); /* write daytime on stdout */
            return -1;
        }
    }

    close(sock_fd);
    exit(0);
}