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 <fcntl.h>
19 #include <string.h>
20 #include <unistd.h>
21 #include <arpa/inet.h>
22 #include <linux/if.h>
23 #include <linux/if_tun.h>
24 #include <sys/ioctl.h>
25 #include <sys/uio.h>
26
27 #include "clatd.h"
28
29 /* function: tun_open
30 * tries to open the tunnel device
31 */
tun_open()32 int tun_open() {
33 int fd;
34
35 fd = open("/dev/tun", O_RDWR);
36 if(fd < 0) {
37 fd = open("/dev/net/tun", O_RDWR);
38 }
39
40 return fd;
41 }
42
43 /* function: tun_alloc
44 * creates a tun interface and names it
45 * dev - the name for the new tun device
46 */
tun_alloc(char * dev,int fd)47 int tun_alloc(char *dev, int fd) {
48 struct ifreq ifr;
49 int err;
50
51 memset(&ifr, 0, sizeof(ifr));
52
53 ifr.ifr_flags = IFF_TUN;
54 if( *dev ) {
55 strncpy(ifr.ifr_name, dev, IFNAMSIZ);
56 ifr.ifr_name[IFNAMSIZ-1] = '\0';
57 }
58
59 if( (err = ioctl(fd, TUNSETIFF, (void *) &ifr)) < 0 ){
60 close(fd);
61 return err;
62 }
63 strcpy(dev, ifr.ifr_name);
64 return 0;
65 }
66
67 /* function: set_nonblocking
68 * sets a filedescriptor to non-blocking mode
69 * fd - the filedescriptor
70 * returns: 0 on success, -1 on failure
71 */
set_nonblocking(int fd)72 int set_nonblocking(int fd) {
73 int flags = fcntl(fd, F_GETFL);
74 if (flags == -1) {
75 return flags;
76 }
77 return fcntl(fd, F_SETFL, flags | O_NONBLOCK);
78 }
79
80 /* function: send_tun
81 * sends a clat_packet to a tun interface
82 * fd - the tun filedescriptor
83 * out - the packet to send
84 * iov_len - the number of entries in the clat_packet
85 * returns: number of bytes read on success, -1 on failure
86 */
send_tun(int fd,clat_packet out,int iov_len)87 int send_tun(int fd, clat_packet out, int iov_len) {
88 return writev(fd, out, iov_len);
89 }
90