#include <sys/socket.h>
#include <sys/ioctl.h>
#include <sys/sockio.h>

#include <net/if.h>

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

static void *
ifioctl(void *arg)
{
	const char *name = arg;
	struct ifreq ifr;
	size_t len;
	int s;

	len = strlen(name);
	if (len >= sizeof(ifr.ifr_name))
		errx(1, "interface name is too long");

	s = socket(AF_INET, SOCK_DGRAM, 0);
	if (s == -1)
		err(1, "%s socket", __func__);

	for (;;) {
		memset(&ifr, 0, sizeof(ifr));
		memcpy(ifr.ifr_name, name, len);
		if (ioctl(s, SIOCIFCREATE, &ifr) == -1)
			warn("SIOCIFCREATE %s", name);

		memset(&ifr, 0, sizeof(ifr));
		memcpy(ifr.ifr_name, name, len);
		if (ioctl(s, SIOCIFDESTROY, &ifr) == -1)
			warn("SIOCIFDESTROY %s", name);
	}

	return (NULL);
}

static void *
dvthing(void *arg)
{
	const char *name = arg;
	int fd;
	unsigned int yay = 0, nay = 0;
	ssize_t rv;
	uint8_t buf[65536];

	for (;;) {
		fd = open(name, O_RDWR);
		if (fd == -1) {
			nay++;
			if (errno != ECANCELED || (nay % 1000) == 0) {
				warn("open %s (yay %u vs nay %u)", name,
				    yay, nay);
			}
			continue;
		}
		yay++;

pain:
		rv = read(fd, buf, sizeof(buf));
		if (rv == -1) {
			warn("read");
			if (errno == EIO) {
				int nfd = open(name, O_RDWR);
				if (nfd == -1)
					warn("open new %s", name);
				else {
					close(fd);
					fd = nfd;
					goto pain;
				}
			}
		}

		close(fd);
	}

	return (NULL);
}

__dead static void
usage(void)
{
	extern char *__progname;

	fprintf(stderr, "usage: %s ifname\n", __progname);

	exit(1);
}

int
main(int argc, char *argv[])
{
	int ecode;
	pthread_t if_tid, dv_tid;
	void *ret;

	if (argc != 2)
		usage();

	if (chdir("/dev") == -1)
		err(1, "/dev");

	ecode = pthread_create(&if_tid, NULL, ifioctl, argv[1]);
	if (ecode != 0)
		errc(1, ecode, "create ifioctl thread");

	ecode = pthread_create(&dv_tid, NULL, dvthing, argv[1]);
	if (ecode != 0)
		errc(1, ecode, "create dvthing thread");

	ecode = pthread_join(if_tid, &ret);
	if (ecode != 0)
		errc(1, ecode, "join ifioctl thread");

	ecode = pthread_join(dv_tid, &ret);
	if (ecode != 0)
		errc(1, ecode, "join dvthing thread");

	exit(0);
}