/* cc -pthread tcpr.c */
#include <sys/cdefs.h>
#include <sys/types.h>
#include <sys/socket.h>

#include <machine/atomic.h>

#include <netinet/in.h>
#include <netdb.h>

#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <pthread.h>

#define	PORT	8993
#define	SPORT	__XSTRING(PORT)

static int listening;
static char msg[] = { 1, 2, 3, 4 };

static void
filladdr(struct addrinfo *hints, struct addrinfo **res)
{
	int error;

	memset(hints, 0, sizeof(*hints));
	hints->ai_family = AF_INET;
	hints->ai_socktype = SOCK_STREAM;
	hints->ai_flags = AI_NUMERICHOST;

	if ((error = getaddrinfo("127.0.0.1", SPORT, hints, res)) != 0) {
		printf("getaddrinfo: %s\n", gai_strerror(error));
		abort();
	}
}

static void *
server_thr(void *data)
{
	struct addrinfo hints, *res;
	struct sockaddr_in addr;
	socklen_t sz;
	int clfd, error, fd, reuse;

	filladdr(&hints, &res);
	fd = socket(PF_INET, SOCK_STREAM, 0);
	if (fd == -1) {
		printf("socket: %d\n", errno);
		abort();
	}

	reuse = 1;
	setsockopt(fd, SOL_SOCKET, SO_REUSEPORT, &reuse, sizeof(reuse));
	setsockopt(fd, SOL_SOCKET, SO_NOSIGPIPE, &reuse, sizeof(reuse));
	if (bind(fd, res->ai_addr, res->ai_addrlen) == -1) {
		printf("bind: %d\n", errno);
		abort();
	}

	if (listen(fd, SOMAXCONN) == -1) {
		printf("listen: %d\n", errno);
		abort();
	}

	sz = sizeof(addr);
	atomic_store_int(&listening, 1);
	clfd = accept(fd, (struct sockaddr *)&addr, &sz);
	printf("got client\n");
	for (;;) {
		error = write(clfd, msg, sizeof(msg));
		if (error == 0) {
			printf("connection closed (good!)\n");
			break;
		} else if (error < 0) {
			if (errno == EPIPE)
				printf("pipe gone (good!)\n");
			else
				printf("write fail (bad!): %d\n", errno);
			break;
		}
	}

	close(clfd);
	close(fd);

	return (NULL);
}

int
main(int argc, char *argv[])
{
	void *ret;
	pthread_t thr;
	struct addrinfo hints, *res;
	int error, fd;

	pthread_create(&thr, NULL, server_thr, NULL);

	filladdr(&hints, &res);
	fd = socket(PF_INET, SOCK_STREAM, 0);
	if (fd == -1) {
		printf("client socket: %d\n", errno);
		abort();
	}

	printf("waiting for server\n");
	while (atomic_load_int(&listening) != 1)
		usleep(1000);

	printf("attempting to connect\n");

	for (;;) {
		if (connect(fd, res->ai_addr, res->ai_addrlen) == 0)
			break;
		if (errno != ECONNREFUSED) {
			printf("connect: %d\n", errno);
			abort();
		}
		usleep(1000);
	}

	printf("connected, closing\n");
	shutdown(fd, SHUT_RDWR);
	close(fd);

	printf("waiting\n");
	pthread_join(thr, &ret);
	return (0);
}