| /* |
| * Copyright 2014 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| * |
| * tun.c - tun device functions |
| */ |
| #include <arpa/inet.h> |
| #include <fcntl.h> |
| #include <linux/if.h> |
| #include <linux/if_tun.h> |
| #include <string.h> |
| #include <sys/ioctl.h> |
| #include <sys/uio.h> |
| #include <unistd.h> |
| |
| #include "clatd.h" |
| |
| /* function: tun_open |
| * tries to open the tunnel device |
| */ |
| int tun_open() { |
| int fd; |
| |
| fd = open("/dev/tun", O_RDWR); |
| if (fd < 0) { |
| fd = open("/dev/net/tun", O_RDWR); |
| } |
| |
| return fd; |
| } |
| |
| /* function: tun_alloc |
| * creates a tun interface and names it |
| * dev - the name for the new tun device |
| */ |
| int tun_alloc(char *dev, int fd) { |
| struct ifreq ifr; |
| int err; |
| |
| memset(&ifr, 0, sizeof(ifr)); |
| |
| ifr.ifr_flags = IFF_TUN; |
| if (*dev) { |
| strncpy(ifr.ifr_name, dev, IFNAMSIZ); |
| ifr.ifr_name[IFNAMSIZ - 1] = '\0'; |
| } |
| |
| if ((err = ioctl(fd, TUNSETIFF, (void *)&ifr)) < 0) { |
| close(fd); |
| return err; |
| } |
| strcpy(dev, ifr.ifr_name); |
| return 0; |
| } |
| |
| /* function: set_nonblocking |
| * sets a filedescriptor to non-blocking mode |
| * fd - the filedescriptor |
| * returns: 0 on success, -1 on failure |
| */ |
| int set_nonblocking(int fd) { |
| int flags = fcntl(fd, F_GETFL); |
| if (flags == -1) { |
| return flags; |
| } |
| return fcntl(fd, F_SETFL, flags | O_NONBLOCK); |
| } |
| |
| /* function: send_tun |
| * sends a clat_packet to a tun interface |
| * fd - the tun filedescriptor |
| * out - the packet to send |
| * iov_len - the number of entries in the clat_packet |
| * returns: number of bytes read on success, -1 on failure |
| */ |
| int send_tun(int fd, clat_packet out, int iov_len) { return writev(fd, out, iov_len); } |