#include <string.h>
#include <sys/socket.h>  /* For struct sockaddr, socket, accept, listen, bind */
#include <netinet/in.h>  /* For struct sockaddr_in */
#include <arpa/inet.h>   /* For htons, htonl, inet_pton */
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>       /* For errno */
#include <stdint.h>
#include <unistd.h>      /* For close, read, write */

int main (int argc, char * argv []) {
    uint16_t port = 12345;
    if (argc > 1)
	port = strtoul(argv[1], NULL, 10);

    struct sockaddr_in addr;
    addr.sin_family = AF_INET;
    addr.sin_port = htons(port);
    addr.sin_addr.s_addr = htonl(INADDR_ANY);

    int srv = socket(AF_INET, SOCK_STREAM, 0);
    if (srv < 0) {
	perror("could not create socket");
	return EXIT_FAILURE;
    }

    if (bind(srv, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
	perror("could not bind local address");
	close(srv);
	return EXIT_FAILURE;
    }

    if (listen(srv, 10) < 0) {
	perror("could not set server socket as passive socket");
	close(srv);
	return EXIT_FAILURE;
    };

    int conn = accept(srv, NULL, NULL);
    if (conn < 0) {
	perror("could not accept connection");
	close(srv);
	return EXIT_FAILURE;
    }

    close(srv);
    for (;;) {
	char buffer[4096];
	ssize_t len = read(conn, buffer, 4096);
	if (len < 0) {
	    perror("could not read from connection");
	    close(conn);
	    return EXIT_FAILURE;
	} else if (len == 0) {
	    close(conn);
	    return EXIT_SUCCESS;
	}
	fwrite(buffer, len, 1, stdout);
    }
}