iodine/tun.c

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/*
* Copyright (c) 2006
* Bjorn Andersson <flex@kryo.se>,
* Erik Ekman <yarrick@kryo.se>
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*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <stdint.h>
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#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <err.h>
#include "tun.h"
#define TUN_MAX_TRY 50
int tun_fd = -1;
char *tun_device = NULL;
#ifdef LINUX
#include <sys/ioctl.h>
#include <net/if.h>
#include <linux/if_tun.h>
int
open_tun()
{
struct ifreq ifreq;
int i;
if (tun_device == NULL)
tun_device = "/dev/net/tun";
if ((tun_fd = open(tun_device, O_RDWR)) < 0)
err(1, "open_tun: %s: %s", tun_device, strerror(errno));
bzero(&ifreq, sizeof(ifreq));
ifreq.ifr_flags = IFF_TUN;
for (i = 0; i < TUN_MAX_TRY; i++) {
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snprintf(ifreq.ifr_name, IFNAMSIZ, "dns%d", i);
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if (ioctl(tun_fd, TUNSETIFF, (void *) &ifreq) != -1) {
printf("opened %s\n", ifreq.ifr_name);
return 0;
}
if (errno != EBUSY)
err(1, "open_tun: ioctl[TUNSETIFF]: %s", strerror(errno));
}
err(1, "open_tun: Couldn't set interface name.\n");
return 1;
}
#else /* BSD */
int
open_tun()
{
if (tun_device != NULL) {
if ((tun_fd = open(tun_device, O_RDWR)) < 0)
err(1, "open_tun: %s: %s", tun_device, strerror(errno));
} else {
char tun_name[50];
int i;
for (i = 0; i < TUN_MAX_TRY; i++) {
snprintf(tun_name, sizeof(tun_name), "/dev/tun%d", i);
if ((tun_fd = open(tun_name, O_RDWR)) >= 0)
return 0;
if (errno == ENOENT)
break;
}
err(1, "open_tun: Failed to open tunneling device.");
}
return 0;
}
#endif /* LINUX */
void
close_tun()
{
if (tun_fd >= 0)
close(tun_fd);
}
int
write_tun(uint8_t *buf, int len)
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{
if (write(tun_fd, buf, len) != len)
err(1, "write_tun: %s", strerror(errno));
return 0;
}
int
read_tun(uint8_t *buf, int len)
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{
return read(tun_fd, buf, len);
}