1 /*
2     VTun - Virtual Tunnel over TCP/IP network.
3 
4     Copyright (C) 1998-2016  Maxim Krasnyansky <max_mk@yahoo.com>
5 
6     VTun has been derived from VPPP package by Maxim Krasnyansky.
7 
8     This program is free software; you can redistribute it and/or modify
9     it under the terms of the GNU General Public License as published by
10     the Free Software Foundation; either version 2 of the License, or
11     (at your option) any later version.
12 
13     This program is distributed in the hope that it will be useful,
14     but WITHOUT ANY WARRANTY; without even the implied warranty of
15     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16     GNU General Public License for more details.
17  */
18 
19 /*
20  * $Id: tun_dev.c,v 1.5.2.3 2016/10/01 21:46:01 mtbishop Exp $
21  */
22 
23 #include "config.h"
24 
25 #include <unistd.h>
26 #include <fcntl.h>
27 #include <stdlib.h>
28 #include <stdio.h>
29 #include <string.h>
30 #include <syslog.h>
31 
32 #include <sys/ioctl.h>
33 #include <net/if_tun.h>
34 
35 #include "vtun.h"
36 #include "lib.h"
37 
38 extern int extended_mode;
39 
40 /*
41  * Allocate TUN device, returns opened fd.
42  * Stores dev name in the first arg(must be large enough).
43  */
tun_open(char * dev)44 int tun_open(char *dev)
45 {
46     char tunname[14];
47     int i, fd = -1;
48 
49     if( *dev ){
50        sprintf(tunname, "/dev/%s", dev);
51        fd = open(tunname, O_RDWR);
52     } else {
53        for(i=0; i < 255; i++){
54           sprintf(tunname, "/dev/tun%d", i);
55           /* Open device */
56           if( (fd=open(tunname, O_RDWR)) > 0 ){
57              sprintf(dev, "tun%d", i);
58              break;
59           }
60        }
61     }
62     if( fd > -1 ){
63        ioctl(fd, TUNSLMODE, &extended_mode);
64        ioctl(fd, TUNSIFHEAD, &extended_mode);
65     }
66     return fd;
67 }
68 
tun_close(int fd,char * dev)69 int tun_close(int fd, char *dev)
70 {
71     return close(fd);
72 }
73 
74 /* Read/write frames from/to TUN device */
tun_write(int fd,char * buf,int len)75 int tun_write(int fd, char *buf, int len)
76 {
77     return write(fd, buf, len);
78 }
79 
tun_read(int fd,char * buf,int len)80 int tun_read(int fd, char *buf, int len)
81 {
82     return read(fd, buf, len);
83 }
84