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
38 using android::base::StringPrintf;
39
40 namespace android {
41 namespace net {
42
init()43 int 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
destroy()87 void TunInterface::destroy() {
88 if (mFd != -1) {
89 close(mFd);
90 mFd = -1;
91 }
92 }
93
94 } // namespace net
95 } // namespace android
96