#include <sys/param.h>
#include <sys/socket.h>

#include <netinet/in.h>

#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#define PORT	23457

int
main(int argc, char **argv)
{
	struct sockaddr_in sin;
	int listenfd, connfd, pid, ret;
	char buf[100];

	if ((listenfd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
		err(1, "socket error");

	memset(&sin, 0, sizeof(sin));
	sin.sin_family = AF_INET;
	sin.sin_port = htons(PORT);

	if (bind(listenfd, (struct sockaddr *) &sin,
		 sizeof(sin)) < 0)
		err(1, "bind error");

	if (listen(listenfd, 1024) < 0)
		err(1, "listen error");

	pid = fork();

	if (pid == -1)
		err(1, "fork error");

	if (pid != 0) {

		close(listenfd);
		sleep(1);

		if ((connfd = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
			(void)kill(pid, SIGTERM);
			err(1, "parent: socket error");
		}
		if (connect(connfd, (struct sockaddr *)&sin,
			    sizeof(sin)) < 0) {
			(void)kill(pid, SIGTERM);
			err(1, "parent: connect error");
		}

		/* Make socket non-blocking. */
		if (fcntl(connfd, F_SETFL, O_NONBLOCK) == -1) {
			(void)kill(pid, SIGTERM);
			err(1, "parent: fcntl error");
		}

		sleep (1);

		/* Normally this should return 0. */
		ret = recv(connfd, buf, sizeof(buf), 0);

		printf("parent: recv returned %d (errno = %d)\n", ret, errno);

		close(connfd);

		(void)kill(pid, SIGTERM);
	} else {
		if ((connfd = accept(listenfd, (struct sockaddr *)NULL,
			    NULL)) < 0) {
			err(1, "child: accept error");
		}

		if (close(connfd) < 0)
			err(1, "child: close error");

		sleep(10);
	}
	exit(0);
}