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 */ 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 */ 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 */ 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 */ 87 int send_tun(int fd, clat_packet out, int iov_len) { 88 return writev(fd, out, iov_len); 89 } 90
