1/* 2 * Copyright 2017 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_interface.cpp - creates tun interfaces for testing purposes 17 */ 18 19#include <fcntl.h> 20#include <netdb.h> 21#include <stdlib.h> 22#include <unistd.h> 23#include <sys/ioctl.h> 24#include <sys/socket.h> 25#include <sys/stat.h> 26#include <sys/types.h> 27#include <linux/if.h> 28#include <linux/if_tun.h> 29 30#include <android-base/stringprintf.h> 31#include <android-base/strings.h> 32#include <netutils/ifc.h> 33 34#include "tun_interface.h" 35 36#define TUN_DEV "/dev/tun" 37 38using android::base::StringPrintf; 39 40namespace android { 41namespace net { 42 43int TunInterface::init() { 44 // Generate a random ULA address pair. 45 arc4random_buf(&mSrcAddr, sizeof(mSrcAddr)); 46 mSrcAddr.s6_addr[0] = 0xfd; 47 memcpy(&mDstAddr, &mSrcAddr, sizeof(mDstAddr)); 48 mDstAddr.s6_addr[15] ^= 1; 49 50 // Convert the addresses to strings because that's what ifc_add_address takes. 51 char srcStr[INET6_ADDRSTRLEN], dstStr[INET6_ADDRSTRLEN]; 52 sockaddr_in6 src6 = { .sin6_family = AF_INET6, .sin6_addr = mSrcAddr, }; 53 sockaddr_in6 dst6 = { .sin6_family = AF_INET6, .sin6_addr = mDstAddr, }; 54 int flags = NI_NUMERICHOST; 55 if (getnameinfo((sockaddr *) &src6, sizeof(src6), srcStr, sizeof(srcStr), NULL, 0, flags) || 56 getnameinfo((sockaddr *) &dst6, sizeof(dst6), dstStr, sizeof(dstStr), NULL, 0, flags)) { 57 return -EINVAL; 58 } 59 60 // Create a tun interface with a name based on our PID. 61 mIfName = StringPrintf("netdtest%u", getpid()); 62 struct ifreq ifr = { 63 .ifr_ifru = { .ifru_flags = IFF_TUN }, 64 }; 65 snprintf(ifr.ifr_name, sizeof(ifr.ifr_name), "%s", mIfName.c_str()); 66 67 mFd = open(TUN_DEV, O_RDWR | O_NONBLOCK | O_CLOEXEC); 68 if (mFd == -1) return -errno; 69 70 int ret = ioctl(mFd, TUNSETIFF, &ifr, sizeof(ifr)); 71 if (ret == -1) { 72 ret = -errno; 73 close(mFd); 74 return ret; 75 } 76 77 if (ifc_add_address(ifr.ifr_name, srcStr, 64) || 78 ifc_add_address(ifr.ifr_name, dstStr, 64)) { 79 ret = -errno; 80 close(mFd); 81 return ret; 82 } 83 84 return 0; 85} 86 87void TunInterface::destroy() { 88 if (mFd != -1) { 89 close(mFd); 90 mFd = -1; 91 } 92} 93 94} // namespace net 95} // namespace android 96