797.c

#include <arpa/inet.h>
#include <errno.h>
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <unistd.h>

const char* response =
    "HTTP/1.1 797 This is the last page of the Internet. Go back\r\n"
    "Server: lol\r\n"
    "Connection: close\r\n"
    "Content-Type: text/html\r\n"
    "\r\n"
    "<h1>this is the last page of the internet</h1>\r\n"
    "<i>yada yada yada</i>\r\n";

int
create_server()
{
    int servfd, one = 1;
    struct sockaddr_in addr = {
        .sin_family = AF_INET,
        .sin_addr = INADDR_ANY,
        .sin_port = htons(797)
    };

    if((servfd = socket(PF_INET, SOCK_STREAM, 0)) < 0) {
        perror("socket");
        exit(1);
    }

    if(setsockopt(servfd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one)) < 0) {
        perror("setsockopt");
        exit(1);
    }

    if(bind(servfd, (struct sockaddr*)&addr, sizeof(addr)) < 0) {
        perror("bind");
        exit(1);
    }

    if(listen(servfd, 32) < 0) {
        perror("listen");
    }

    return servfd;
}

void
handle_client(long fd)
{
    size_t offset = 0;
    size_t len = strlen(response);
    while(offset < len) {
        ssize_t sent = send(fd, response + offset, len - offset, 0);
        if(sent <= 0) {
            if(errno == EINTR) {
                continue;
            } else {
                break;
            }
        }
        offset += sent;
    }
    shutdown(fd, SHUT_RDWR);
    close(fd);
}

int
main()
{
    int servfd = create_server();

    while(1) {
        pthread_t thr;
        struct sockaddr_in client_addr;
        socklen_t client_addr_len = sizeof(client_addr);
        long sock = accept(servfd, (struct sockaddr*)&client_addr, &client_addr_len);
        if(sock < 0) {
            continue;
        }
        pthread_create(&thr, NULL, (void*(*)(void*))handle_client, (void*)sock);
        pthread_detach(thr);
    }
}