| /* |
| * Copyright 2017 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_interface.cpp - creates tun interfaces for testing purposes |
| */ |
| |
| #include <fcntl.h> |
| #include <netdb.h> |
| #include <stdlib.h> |
| #include <unistd.h> |
| #include <linux/if.h> |
| #include <linux/if_tun.h> |
| #include <net/if.h> |
| #include <netinet/in.h> |
| #include <sys/ioctl.h> |
| #include <sys/socket.h> |
| #include <sys/stat.h> |
| #include <sys/types.h> |
| |
| #include <android-base/stringprintf.h> |
| #include <android-base/strings.h> |
| #include <netutils/ifc.h> |
| |
| #include "tun_interface.h" |
| |
| #define TUN_DEV "/dev/tun" |
| |
| using android::base::StringPrintf; |
| |
| namespace android { |
| namespace net { |
| |
| int TunInterface::init() { |
| // Generate a random ULA address pair. |
| arc4random_buf(&mSrcAddr, sizeof(mSrcAddr)); |
| mSrcAddr.s6_addr[0] = 0xfd; |
| memcpy(&mDstAddr, &mSrcAddr, sizeof(mDstAddr)); |
| mDstAddr.s6_addr[15] ^= 1; |
| |
| // Convert the addresses to strings because that's what ifc_add_address takes. |
| char srcStr[INET6_ADDRSTRLEN], dstStr[INET6_ADDRSTRLEN]; |
| sockaddr_in6 src6 = { .sin6_family = AF_INET6, .sin6_addr = mSrcAddr, }; |
| sockaddr_in6 dst6 = { .sin6_family = AF_INET6, .sin6_addr = mDstAddr, }; |
| int flags = NI_NUMERICHOST; |
| if (getnameinfo((sockaddr *) &src6, sizeof(src6), srcStr, sizeof(srcStr), NULL, 0, flags) || |
| getnameinfo((sockaddr *) &dst6, sizeof(dst6), dstStr, sizeof(dstStr), NULL, 0, flags)) { |
| return -EINVAL; |
| } |
| |
| // Create a tun interface with a name based on our PID and some randomness. |
| // iptables will only accept interfaces whose name is up to IFNAMSIZ - 1 bytes long. |
| mIfName = StringPrintf("netd%u_%u", getpid(), arc4random()); |
| if (mIfName.size() >= IFNAMSIZ) { |
| mIfName.resize(IFNAMSIZ - 1); |
| } |
| struct ifreq ifr = { |
| .ifr_ifru = { .ifru_flags = IFF_TUN }, |
| }; |
| strlcpy(ifr.ifr_name, mIfName.c_str(), sizeof(ifr.ifr_name)); |
| |
| mFd = open(TUN_DEV, O_RDWR | O_NONBLOCK | O_CLOEXEC); |
| if (mFd == -1) return -errno; |
| |
| int ret = ioctl(mFd, TUNSETIFF, &ifr, sizeof(ifr)); |
| if (ret == -1) { |
| ret = -errno; |
| close(mFd); |
| return ret; |
| } |
| |
| if (ifc_add_address(ifr.ifr_name, srcStr, 64) || |
| ifc_add_address(ifr.ifr_name, dstStr, 64)) { |
| ret = -errno; |
| close(mFd); |
| return ret; |
| } |
| |
| mIfIndex = if_nametoindex(ifr.ifr_name); |
| |
| return 0; |
| } |
| |
| void TunInterface::destroy() { |
| if (mFd != -1) { |
| close(mFd); |
| mFd = -1; |
| } |
| } |
| |
| } // namespace net |
| } // namespace android |