// SPDX-License-Identifier: EUPL-1.2+
// SPDX-FileCopyrightText: 2022 Alyssa Ross <hi@alyssa.is>

#include "net-util.h"

#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <string.h>
#include <unistd.h>

#include <sys/ioctl.h>

#include <linux/if_tun.h>
#include <linux/sockios.h>

// ifr_name doesn't have to be null terminated.
#pragma GCC diagnostic ignored "-Wstringop-truncation"

int if_up(const char *name)
{
	struct ifreq ifr;
	int fd, r = -1;

	if ((fd = socket(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC, 0)) == -1)
		return -1;

	strncpy(ifr.ifr_name, name, IFNAMSIZ);
	if (ioctl(fd, SIOCGIFFLAGS, &ifr) == -1)
		goto out;
	ifr.ifr_flags |= IFF_UP;
	r = ioctl(fd, SIOCSIFFLAGS, &ifr);
out:
	close(fd);
	return r;
}

int if_rename(const char *name, const char *newname)
{
	int fd, r;
	struct ifreq ifr;

	strncpy(ifr.ifr_name, name, sizeof ifr.ifr_name);
	strncpy(ifr.ifr_newname, newname, sizeof ifr.ifr_newname);

	if (ifr.ifr_newname[sizeof ifr.ifr_newname - 1]) {
		errno = ENAMETOOLONG;
		return -1;
	}

	if (strchr(ifr.ifr_newname, '%')) {
		errno = EINVAL;
		return -1;
	}

	if ((fd = socket(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC, 0)) == -1)
		return -1;
	r = ioctl(fd, SIOCSIFNAME, &ifr);
	close(fd);
	return r;
}

int if_down(const char *name)
{
	struct ifreq ifr;
	int fd, r = -1;

	if ((fd = socket(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC, 0)) == -1)
		return -1;

	strncpy(ifr.ifr_name, name, IFNAMSIZ);
	if (ioctl(fd, SIOCGIFFLAGS, &ifr) == -1)
		goto out;
	ifr.ifr_flags &= ~IFF_UP;
	r = ioctl(fd, SIOCSIFFLAGS, &ifr);
out:
	close(fd);
	return r;
}

int bridge_add(const char *name)
{
	int fd, r;

	if (strnlen(name, IFNAMSIZ) == IFNAMSIZ) {
		errno = ENAMETOOLONG;
		return -1;
	}

	if (strchr(name, '%')) {
		errno = EINVAL;
		return -1;
	}

	if ((fd = socket(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC, 0)) == -1)
		return -1;
	r = ioctl(fd, SIOCBRADDBR, name);
	close(fd);
	return r;
}

int bridge_add_if(const char *brname, const char *ifname)
{
	struct ifreq ifr;
	int fd, r;

	strncpy(ifr.ifr_name, brname, IFNAMSIZ);
	if (!(ifr.ifr_ifindex = if_nametoindex(ifname)))
		return -1;

	if ((fd = socket(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC, 0)) == -1)
		return -1;

	r = ioctl(fd, SIOCBRADDIF, &ifr);
	close(fd);
	return r;
}

int bridge_remove_if(const char *brname, const char *ifname)
{
	struct ifreq ifr;
	int fd, r;

	strncpy(ifr.ifr_name, brname, IFNAMSIZ);
	if (!(ifr.ifr_ifindex = if_nametoindex(ifname)))
		return -1;

	if ((fd = socket(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC, 0)) == -1)
		return -1;

	r = ioctl(fd, SIOCBRDELIF, &ifr);
	close(fd);
	return r;
}

int bridge_delete(const char *name)
{
	int fd, r;

	if (if_down(name) == -1)
		warn("setting %s down", name);

	if ((fd = socket(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC, 0)) == -1)
		return -1;

	r = ioctl(fd, SIOCBRDELBR, name);
	close(fd);
	return r;
}

int tap_open(char name[static IFNAMSIZ], int flags)
{
	struct ifreq ifr;
	int fd;

	if (name[IFNAMSIZ - 1]) {
		errno = ENAMETOOLONG;
		return -1;
	}

	strncpy(ifr.ifr_name, name, IFNAMSIZ - 1);
	ifr.ifr_flags = IFF_TAP|flags;

	if ((fd = open("/dev/net/tun", O_RDWR)) == -1)
		return -1;
	if (ioctl(fd, TUNSETIFF, &ifr) == -1) {
		close(fd);
		return -1;
	}

	strncpy(name, ifr.ifr_name, IFNAMSIZ);
	return fd;
}