#include <sys/types.h>
#include <sys/socket.h>
#include <sys/un.h>

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

static int child, finish = 0, seconds = 30;

static void
doalarm(int sig)
{

	finish = 1;
}

static int
conn(const char *path, int server)
{
	struct sockaddr_un sun;
	int sock;

	sock = socket(AF_UNIX, SOCK_STREAM, 0);
	if (sock < 0)
		err(1, "socket()");
	bzero(&sun, sizeof(sun));
	sun.sun_len = sizeof(sun);
	sun.sun_family = AF_UNIX;
	strlcpy(sun.sun_path, path, sizeof(sun.sun_path));
	if (server) {
		if (bind(sock, (struct sockaddr *)&sun, sizeof(sun)) == -1)
			err(1, "bind()");
		if (listen(sock, 5) == -1)
			err(1, "listen()");
	} else {
		if (connect(sock, (struct sockaddr *)&sun, sizeof(sun)) == -1)
			err(1, "connect()");
	}
	return (sock);
}

static void
sendproc(const char *path, int sock)
{
	ssize_t done;
	char byte;
	int packets;

	packets = 0;
	byte = 0x55;
	for (;;) {
		done = send(sock, &byte, 1, 0);
		assert(done == 1);
		done = recv(sock, &byte, 1, MSG_WAITALL);
		assert(done == 1);
		packets++;
		if (finish) {
			kill(child, SIGKILL);
			unlink(path);
			printf("%d packets/s\n", packets / seconds);
			exit(0);
		}
	}
}

static void
recvproc(int sock)
{
	char byte;
	ssize_t done;

	for (;;) {
		done = recv(sock, &byte, 1, MSG_WAITALL);
		assert(done == 1);
		done = send(sock, &byte, 1, 0);
		assert(done == 1);
	}
}

int
main(int argc, char *argv[])
{
	char path[PATH_MAX];
	int fd;

	switch (argc) {
	case 1:
		break;
	case 2:
		seconds = atoi(argv[1]);
		if (seconds > 0)
			break;
		/* FALLTHROUGH */
	default:
		errx(1, "usage: %s <seconds>", getprogname());
	}

	strlcpy(path, "/tmp/unixpingpong.XXXXXXXX", sizeof(path));
	fd = mkstemp(path);
	assert(fd >= 0);
	close(fd);
	unlink(path);

	child = fork();
	switch (child) {
	case -1:
		err(1, "fork()");
	case 0:
		sleep(1);
		recvproc(conn(path, 0));
		exit(0);
	default:
		fd = conn(path, 1);
		sleep(1);
		fd = accept(fd, NULL, NULL);
		if (fd < 0)
			err(1, "accept()");
		signal(SIGALRM, doalarm);
		alarm(seconds);
		sendproc(path, fd);
		exit(0);
	}

	exit(0);
}