1 /*
2 * Copyright 2019, 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 "bridge.h"
18
19 #include "log.h"
20
21 #include <errno.h>
22 #include <net/if.h>
23 #include <string.h>
24 #include <sys/ioctl.h>
25 #include <sys/socket.h>
26 #include <sys/types.h>
27 #include <unistd.h>
28
Bridge(const std::string & bridgeName)29 Bridge::Bridge(const std::string& bridgeName) : mBridgeName(bridgeName) {
30 }
31
~Bridge()32 Bridge::~Bridge() {
33 if (mSocketFd != -1) {
34 ::close(mSocketFd);
35 mSocketFd = -1;
36 }
37 }
38
init()39 Result Bridge::init() {
40 Result res = createSocket();
41 if (!res) {
42 return res;
43 }
44 res = createBridge();
45 if (!res) {
46 return res;
47 }
48 return Result::success();
49 }
50
addInterface(const std::string & interfaceName)51 Result Bridge::addInterface(const std::string& interfaceName) {
52 return doInterfaceOperation(interfaceName, SIOCBRADDIF, "add");
53 }
54
removeInterface(const std::string & interfaceName)55 Result Bridge::removeInterface(const std::string& interfaceName) {
56 return doInterfaceOperation(interfaceName, SIOCBRDELIF, "remove");
57 }
58
createSocket()59 Result Bridge::createSocket() {
60 if (mSocketFd != -1) {
61 return Result::error("Bridge already initialized");
62 }
63 mSocketFd = ::socket(AF_INET, SOCK_DGRAM | SOCK_CLOEXEC, 0);
64 if (mSocketFd < 0) {
65 return Result::error("Unable to create socket for bridge: %s",
66 strerror(errno));
67 }
68 return Result::success();
69 }
70
createBridge()71 Result Bridge::createBridge() {
72 int res = ::ioctl(mSocketFd, SIOCBRADDBR, mBridgeName.c_str());
73 if (res < 0) {
74 // If the bridge already exists we just keep going, that's fine.
75 // Otherwise something went wrong.
76 if (errno != EEXIST) {
77 return Result::error("Cannot create bridge %s: %s",
78 mBridgeName.c_str(), strerror(errno));
79 }
80 }
81
82 struct ifreq request;
83 memset(&request, 0, sizeof(request));
84 // Determine interface index of bridge
85 request.ifr_ifindex = if_nametoindex(mBridgeName.c_str());
86 if (request.ifr_ifindex == 0) {
87 return Result::error("Unable to get bridge %s interface index",
88 mBridgeName.c_str());
89 }
90 // Get bridge interface flags
91 strlcpy(request.ifr_name, mBridgeName.c_str(), sizeof(request.ifr_name));
92 res = ::ioctl(mSocketFd, SIOCGIFFLAGS, &request);
93 if (res != 0) {
94 return Result::error("Unable to get interface flags for bridge %s: %s",
95 mBridgeName.c_str(), strerror(errno));
96 }
97
98 if ((request.ifr_flags & IFF_UP) != 0) {
99 // Bridge is already up, it's ready to go
100 return Result::success();
101 }
102
103 // Bridge is not up, it needs to be up to work
104 request.ifr_flags |= IFF_UP;
105 res = ::ioctl(mSocketFd, SIOCSIFFLAGS, &request);
106 if (res != 0) {
107 return Result::error("Unable to set interface flags for bridge %s: %s",
108 strerror(errno));
109 }
110
111 return Result::success();
112 }
113
doInterfaceOperation(const std::string & interfaceName,unsigned long operation,const char * operationName)114 Result Bridge::doInterfaceOperation(const std::string& interfaceName,
115 unsigned long operation,
116 const char* operationName) {
117 struct ifreq request;
118 memset(&request, 0, sizeof(request));
119
120 request.ifr_ifindex = if_nametoindex(interfaceName.c_str());
121 if (request.ifr_ifindex == 0) {
122 return Result::error("Bridge unable to %s interface '%s', no such "
123 "interface", operationName, interfaceName.c_str());
124 }
125 strlcpy(request.ifr_name, mBridgeName.c_str(), sizeof(request.ifr_name));
126 int res = ::ioctl(mSocketFd, operation, &request);
127 // An errno of EBUSY most likely indicates that the interface is already
128 // part of the bridge. Ignore this.
129 if (res < 0 && errno != EBUSY) {
130 return Result::error("Bridge unable to %s interface '%s': %s",
131 operationName, interfaceName.c_str(),
132 strerror(errno));
133 }
134 return Result::success();
135 }
136