/*
  *  Copyright (c) 2007, 2008, Andrea Bittau <a.bittau@cs.ucl.ac.uk>
  *
  *  OS dependent API for Linux. TAP routines
  *
  *  This program is free software; you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License as published by
  *  the Free Software Foundation; either version 2 of the License, or
  *  (at your option) any later version.
  *
  *  This program is distributed in the hope that it will be useful,
  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  *  GNU General Public License for more details.
  *
  *  You should have received a copy of the GNU General Public License
  *  along with this program; if not, write to the Free Software
  *  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
  */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <sys/socket.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/time.h>
#include <linux/if.h>
#include <linux/if_ether.h>
#include <netinet/in.h>
#include <linux/if_tun.h>
#include <net/if_arp.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>

#include "osdep.h"

struct tip_linux
{
	int tl_fd;
	struct ifreq tl_ifr;
	int tl_ioctls;
	char tl_name[IFNAMSIZ];
};

static int ti_do_open_linux(struct tif * ti, char * name)
{
	int fd_tap;
	struct ifreq if_request;
	struct tip_linux * priv = ti_priv(ti);

	fd_tap = open(name ? name : "/dev/net/tun", O_RDWR);
	if (fd_tap < 0)
	{
		printf("error opening tap device: %s\n", strerror(errno));
		printf("try \"modprobe tun\"\n");
		return -1;
	}

	memset(&if_request, 0, sizeof(if_request));
	if_request.ifr_flags = IFF_TAP | IFF_NO_PI;
	strncpy(if_request.ifr_name, "at%d", IFNAMSIZ);
	if (ioctl(fd_tap, TUNSETIFF, (void *) &if_request) < 0)
	{
		printf("error creating tap interface: %s\n", strerror(errno));
		close(fd_tap);
		return -1;
	}

	memcpy(priv->tl_name, if_request.ifr_name, IFNAMSIZ);
	memcpy(priv->tl_ifr.ifr_name, priv->tl_name, IFNAMSIZ);

	if ((priv->tl_ioctls = socket(PF_INET, SOCK_DGRAM, 0)) == -1)
	{
		priv->tl_ioctls = 0;
		close(fd_tap);
		return -1;
	}

	return fd_tap;
}

static void ti_do_free(struct tif * ti)
{
	struct tip_fbsd * priv = ti_priv(ti);

	free(priv);
	free(ti);
}

static void ti_close_linux(struct tif * ti)
{
	struct tip_linux * priv = ti_priv(ti);

	close(priv->tl_fd);
	close(priv->tl_ioctls);
	ti_do_free(ti);
}

static char * ti_name_linux(struct tif * ti)
{
	struct tip_linux * priv = ti_priv(ti);

	return priv->tl_name;
}

static int ti_set_mtu_linux(struct tif * ti, int mtu)
{
	struct tip_linux * priv = ti_priv(ti);

	priv->tl_ifr.ifr_mtu = mtu;

	return ioctl(priv->tl_ioctls, SIOCSIFMTU, &priv->tl_ifr);
}

static int ti_get_mtu_linux(struct tif * ti)
{
	int mtu;
	struct tip_linux * priv = ti_priv(ti);

	if (ioctl(priv->tl_ioctls, SIOCSIFMTU, &priv->tl_ifr) != -1)
	{
		mtu = priv->tl_ifr.ifr_mtu;
	}
	else
	{
		mtu = 1500;
	}

	return mtu;
}

static int ti_set_mac_linux(struct tif * ti, unsigned char * mac)
{
	struct tip_linux * priv = ti_priv(ti);

	memcpy(priv->tl_ifr.ifr_hwaddr.sa_data, mac, 6); //-V512
	priv->tl_ifr.ifr_hwaddr.sa_family = ARPHRD_ETHER;

	return ioctl(priv->tl_ioctls, SIOCSIFHWADDR, &priv->tl_ifr);
}

static int ti_set_ip_linux(struct tif * ti, struct in_addr * ip)
{
	struct tip_linux * priv = ti_priv(ti);
	struct sockaddr_in * s_in;

	s_in = (struct sockaddr_in *) &priv->tl_ifr.ifr_addr;
	s_in->sin_family = AF_INET;
	s_in->sin_addr = *ip;

	return ioctl(priv->tl_ioctls, SIOCSIFADDR, &priv->tl_ifr);
}

static int ti_fd_linux(struct tif * ti)
{
	struct tip_linux * priv = ti_priv(ti);

	return priv->tl_fd;
}

static int ti_read_linux(struct tif * ti, void * buf, int len)
{
	return read(ti_fd(ti), buf, len);
}

static int ti_write_linux(struct tif * ti, void * buf, int len)
{
	return write(ti_fd(ti), buf, len);
}

static struct tif * ti_open_linux(char * iface)
{
	struct tif * ti;
	struct tip_linux * priv;
	int fd;

	/* setup ti struct */
	ti = ti_alloc(sizeof(*priv));
	if (!ti) return NULL;
	ti->ti_name = ti_name_linux;
	ti->ti_set_mtu = ti_set_mtu_linux;
	ti->ti_get_mtu = ti_get_mtu_linux;
	ti->ti_close = ti_close_linux;
	ti->ti_fd = ti_fd_linux;
	ti->ti_read = ti_read_linux;
	ti->ti_write = ti_write_linux;
	ti->ti_set_mac = ti_set_mac_linux;
	ti->ti_set_ip = ti_set_ip_linux;

	/* setup iface */
	fd = ti_do_open_linux(ti, iface);
	if (fd == -1)
	{
		ti_do_free(ti);
		return NULL;
	}

	/* setup private state */
	priv = ti_priv(ti);
	priv->tl_fd = fd;

	return ti;
}

EXPORT struct tif * ti_open(char * iface) { return ti_open_linux(iface); }
