1 /*
2 * Copyright (C) 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
17 #include "router.h"
18
19 #include "netlink.h"
20
21 #include <linux/rtnetlink.h>
22
23 #include <errno.h>
24 #include <string.h>
25 #include <unistd.h>
26
Router()27 Router::Router() : mSocketFd(-1) {}
28
~Router()29 Router::~Router() {
30 if (mSocketFd != -1) {
31 ::close(mSocketFd);
32 mSocketFd = -1;
33 }
34 }
35
init()36 Result Router::init() {
37 // Create a netlink socket to the router
38 mSocketFd = ::socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
39 if (mSocketFd == -1) {
40 return Result::error(strerror(errno));
41 }
42 return Result::success();
43 }
44
setDefaultGateway(in_addr_t gateway,unsigned int ifaceIndex)45 Result Router::setDefaultGateway(in_addr_t gateway, unsigned int ifaceIndex) {
46 struct Request {
47 struct nlmsghdr hdr;
48 struct rtmsg msg;
49 char buf[256];
50 } request;
51
52 memset(&request, 0, sizeof(request));
53
54 // Set up a request to create a new route
55 request.hdr.nlmsg_len = NLMSG_LENGTH(sizeof(request.msg));
56 request.hdr.nlmsg_type = RTM_NEWROUTE;
57 request.hdr.nlmsg_flags = NLM_F_REQUEST | NLM_F_CREATE;
58
59 request.msg.rtm_family = AF_INET;
60 request.msg.rtm_dst_len = 0;
61 request.msg.rtm_table = RT_TABLE_MAIN;
62 request.msg.rtm_protocol = RTPROT_BOOT;
63 request.msg.rtm_scope = RT_SCOPE_UNIVERSE;
64 request.msg.rtm_type = RTN_UNICAST;
65
66 addRouterAttribute(request, RTA_GATEWAY, &gateway, sizeof(gateway));
67 addRouterAttribute(request, RTA_OIF, &ifaceIndex, sizeof(ifaceIndex));
68
69 return sendNetlinkMessage(&request, request.hdr.nlmsg_len);
70 }
71
sendNetlinkMessage(const void * data,size_t size)72 Result Router::sendNetlinkMessage(const void* data, size_t size) {
73 struct sockaddr_nl nlAddress;
74 memset(&nlAddress, 0, sizeof(nlAddress));
75 nlAddress.nl_family = AF_NETLINK;
76
77 int res = ::sendto(mSocketFd, data, size, 0, reinterpret_cast<sockaddr*>(&nlAddress),
78 sizeof(nlAddress));
79 if (res == -1) {
80 return Result::error("Unable to send on netlink socket: %s", strerror(errno));
81 }
82 return Result::success();
83 }
84