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