1 /*
2 * Copyright 2014 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 *
16 * tun.c - tun device functions
17 */
18 #include <arpa/inet.h>
19 #include <fcntl.h>
20 #include <linux/if.h>
21 #include <linux/if_tun.h>
22 #include <string.h>
23 #include <sys/ioctl.h>
24 #include <unistd.h>
25
26 #include "common.h"
27
28 /* function: tun_open
29 * tries to open the tunnel device in non-blocking mode
30 */
tun_open()31 int tun_open() {
32 int fd;
33
34 fd = open("/dev/tun", O_RDWR | O_NONBLOCK | O_CLOEXEC);
35 if (fd < 0) {
36 fd = open("/dev/net/tun", O_RDWR | O_NONBLOCK | O_CLOEXEC);
37 }
38
39 return fd;
40 }
41
42 /* function: tun_alloc
43 * creates a tun interface and names it
44 * dev - the name for the new tun device
45 * fd - an open fd to the tun device node
46 * len - the length of the buffer pointed to by dev
47 */
tun_alloc(char * dev,int fd,size_t len)48 int tun_alloc(char *dev, int fd, size_t len) {
49 struct ifreq ifr;
50 int err;
51
52 memset(&ifr, 0, sizeof(ifr));
53
54 ifr.ifr_flags = IFF_TUN;
55 if (*dev) {
56 strncpy(ifr.ifr_name, dev, IFNAMSIZ);
57 ifr.ifr_name[IFNAMSIZ - 1] = '\0';
58 }
59
60 if ((err = ioctl(fd, TUNSETIFF, (void *)&ifr)) < 0) {
61 close(fd);
62 return err;
63 }
64 strlcpy(dev, ifr.ifr_name, len);
65 return 0;
66 }
67