c_client.c

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

int main(int argc, char **argv) {
    int s;
    int sock_fd = socket(AF_INET, SOCK_STREAM, 0);

    struct addrinfo hints, *result;
    memset(&hints, 0, sizeof (struct addrinfo));
    hints.ai_family = AF_INET; /* IPv4 only */
    hints.ai_socktype = SOCK_STREAM; /* TCP */

    s = getaddrinfo("www.illinois.edu", "80", &hints, &result);
    if (s != 0) {
        fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(s));
        exit(1);
    }

    if (connect(sock_fd, result->ai_addr, result->ai_addrlen) == -1) {
        perror("connect");
        exit(2);
    }

    char *buffer = "GET / HTTP/1.0\r\n\r\n";
    printf("SENDING: %s", buffer);
    printf("===\n");

    // For this trivial demo just assume write() sends all bytes in one go and is not interrupted

    write(sock_fd, buffer, strlen(buffer));

    char resp[1000];
    int len = read(sock_fd, resp, 999);
    resp[len] = '\0';
    printf("%s\n", resp);

    return 0;
}