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 */ 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 */ 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
