1 /*
2 * Copyright (C) 2016 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 "wificond/net/nl80211_packet.h"
18
19 #include <android-base/logging.h>
20
21 using std::vector;
22
23 namespace android {
24 namespace wificond {
25
NL80211Packet(const vector<uint8_t> & data)26 NL80211Packet::NL80211Packet(const vector<uint8_t>& data)
27 : data_(data) {
28 data_ = data;
29 }
30
NL80211Packet(const NL80211Packet & packet)31 NL80211Packet::NL80211Packet(const NL80211Packet& packet) {
32 data_ = packet.data_;
33 LOG(WARNING) << "Copy constructor is only used for unit tests";
34 }
35
NL80211Packet(uint16_t type,uint8_t command,uint32_t sequence,uint32_t pid)36 NL80211Packet::NL80211Packet(uint16_t type,
37 uint8_t command,
38 uint32_t sequence,
39 uint32_t pid) {
40 // Initialize the netlink header and generic netlink header.
41 // NLMSG_HDRLEN and GENL_HDRLEN already include the padding size.
42 data_.resize(NLMSG_HDRLEN + GENL_HDRLEN, 0);
43 // Initialize length field.
44 nlmsghdr* nl_header = reinterpret_cast<nlmsghdr*>(data_.data());
45 nl_header->nlmsg_len = data_.size();
46 // Add NLM_F_REQUEST flag.
47 nl_header->nlmsg_flags = nl_header->nlmsg_flags | NLM_F_REQUEST;
48 nl_header->nlmsg_type = type;
49 nl_header->nlmsg_seq = sequence;
50 nl_header->nlmsg_pid = pid;
51
52 genlmsghdr* genl_header =
53 reinterpret_cast<genlmsghdr*>(data_.data() + NLMSG_HDRLEN);
54 genl_header->version = 1;
55 genl_header->cmd = command;
56 // genl_header->reserved is aready 0.
57 }
58
IsValid() const59 bool NL80211Packet::IsValid() const {
60 // Verify the size of packet.
61 if (data_.size() < NLMSG_HDRLEN) {
62 LOG(ERROR) << "Cannot retrieve netlink header.";
63 return false;
64 }
65
66 const nlmsghdr* nl_header = reinterpret_cast<const nlmsghdr*>(data_.data());
67
68 // If type < NLMSG_MIN_TYPE, this should be a reserved control message,
69 // which doesn't carry a generic netlink header.
70 if (GetMessageType() >= NLMSG_MIN_TYPE) {
71 if (data_.size() < NLMSG_HDRLEN + GENL_HDRLEN ||
72 nl_header->nlmsg_len < NLMSG_HDRLEN + GENL_HDRLEN) {
73 LOG(ERROR) << "Cannot retrieve generic netlink header.";
74 return false;
75 }
76 }
77 // If it is an ERROR message, it should be long enough to carry an extra error
78 // code field.
79 // Kernel uses int for this field.
80 if (GetMessageType() == NLMSG_ERROR) {
81 if (data_.size() < NLMSG_HDRLEN + sizeof(int) ||
82 nl_header->nlmsg_len < NLMSG_HDRLEN + sizeof(int)) {
83 LOG(ERROR) << "Broken error message.";
84 return false;
85 }
86 }
87
88 // Verify the netlink header.
89 if (data_.size() < nl_header->nlmsg_len ||
90 nl_header->nlmsg_len < sizeof(nlmsghdr)) {
91 LOG(ERROR) << "Discarding incomplete / invalid message.";
92 return false;
93 }
94 return true;
95 }
96
IsDump() const97 bool NL80211Packet::IsDump() const {
98 return GetFlags() & NLM_F_DUMP;
99 }
100
IsMulti() const101 bool NL80211Packet::IsMulti() const {
102 return GetFlags() & NLM_F_MULTI;
103 }
104
GetCommand() const105 uint8_t NL80211Packet::GetCommand() const {
106 const genlmsghdr* genl_header = reinterpret_cast<const genlmsghdr*>(
107 data_.data() + NLMSG_HDRLEN);
108 return genl_header->cmd;
109 }
110
GetFlags() const111 uint16_t NL80211Packet::GetFlags() const {
112 const nlmsghdr* nl_header = reinterpret_cast<const nlmsghdr*>(data_.data());
113 return nl_header->nlmsg_flags;
114 }
115
GetMessageType() const116 uint16_t NL80211Packet::GetMessageType() const {
117 const nlmsghdr* nl_header = reinterpret_cast<const nlmsghdr*>(data_.data());
118 return nl_header->nlmsg_type;
119 }
120
GetMessageSequence() const121 uint32_t NL80211Packet::GetMessageSequence() const {
122 const nlmsghdr* nl_header = reinterpret_cast<const nlmsghdr*>(data_.data());
123 return nl_header->nlmsg_seq;
124 }
125
GetPortId() const126 uint32_t NL80211Packet::GetPortId() const {
127 const nlmsghdr* nl_header = reinterpret_cast<const nlmsghdr*>(data_.data());
128 return nl_header->nlmsg_pid;
129 }
130
GetErrorCode() const131 int NL80211Packet::GetErrorCode() const {
132 return -*reinterpret_cast<const int*>(data_.data() + NLMSG_HDRLEN);
133 }
134
GetConstData() const135 const vector<uint8_t>& NL80211Packet::GetConstData() const {
136 return data_;
137 }
138
SetCommand(uint8_t command)139 void NL80211Packet::SetCommand(uint8_t command) {
140 genlmsghdr* genl_header = reinterpret_cast<genlmsghdr*>(
141 data_.data() + NLMSG_HDRLEN);
142 genl_header->cmd = command;
143 }
144
AddFlag(uint16_t flag)145 void NL80211Packet::AddFlag(uint16_t flag) {
146 nlmsghdr* nl_header = reinterpret_cast<nlmsghdr*>(data_.data());
147 nl_header->nlmsg_flags |= flag;
148 }
149
SetFlags(uint16_t flags)150 void NL80211Packet::SetFlags(uint16_t flags) {
151 nlmsghdr* nl_header = reinterpret_cast<nlmsghdr*>(data_.data());
152 nl_header->nlmsg_flags = flags;
153 }
154
SetMessageType(uint16_t message_type)155 void NL80211Packet::SetMessageType(uint16_t message_type) {
156 nlmsghdr* nl_header = reinterpret_cast<nlmsghdr*>(data_.data());
157 nl_header->nlmsg_type = message_type;
158 }
159
SetMessageSequence(uint32_t message_sequence)160 void NL80211Packet::SetMessageSequence(uint32_t message_sequence) {
161 nlmsghdr* nl_header = reinterpret_cast<nlmsghdr*>(data_.data());
162 nl_header->nlmsg_seq = message_sequence;
163 }
164
SetPortId(uint32_t pid)165 void NL80211Packet::SetPortId(uint32_t pid) {
166 nlmsghdr* nl_header = reinterpret_cast<nlmsghdr*>(data_.data());
167 nl_header->nlmsg_pid = pid;
168 }
169
AddAttribute(const BaseNL80211Attr & attribute)170 void NL80211Packet::AddAttribute(const BaseNL80211Attr& attribute) {
171 const vector<uint8_t>& append_data = attribute.GetConstData();
172 // Append the data of |attribute| to |this|.
173 data_.insert(data_.end(), append_data.begin(), append_data.end());
174 nlmsghdr* nl_header = reinterpret_cast<nlmsghdr*>(data_.data());
175 // We don't need to worry about padding for a nl80211 packet.
176 // Because as long as all sub attributes have padding, the payload is aligned.
177 nl_header->nlmsg_len += append_data.size();
178 }
179
AddFlagAttribute(int attribute_id)180 void NL80211Packet::AddFlagAttribute(int attribute_id) {
181 // We only need to append a header for flag attribute.
182 // Make space for the new attribute.
183 data_.resize(data_.size() + NLA_HDRLEN, 0);
184 nlattr* flag_header =
185 reinterpret_cast<nlattr*>(data_.data() + data_.size() - NLA_HDRLEN);
186 flag_header->nla_type = attribute_id;
187 flag_header->nla_len = NLA_HDRLEN;
188 nlmsghdr* nl_header = reinterpret_cast<nlmsghdr*>(data_.data());
189 nl_header->nlmsg_len += NLA_HDRLEN;
190 }
191
HasAttribute(int id) const192 bool NL80211Packet::HasAttribute(int id) const {
193 return BaseNL80211Attr::GetAttributeImpl(
194 data_.data() + NLMSG_HDRLEN + GENL_HDRLEN,
195 data_.size() - NLMSG_HDRLEN - GENL_HDRLEN,
196 id, nullptr, nullptr);
197 }
198
GetAttribute(int id,NL80211NestedAttr * attribute) const199 bool NL80211Packet::GetAttribute(int id,
200 NL80211NestedAttr* attribute) const {
201 uint8_t* start = nullptr;
202 uint8_t* end = nullptr;
203 if (!BaseNL80211Attr::GetAttributeImpl(
204 data_.data() + NLMSG_HDRLEN + GENL_HDRLEN,
205 data_.size() - NLMSG_HDRLEN - GENL_HDRLEN,
206 id, &start, &end) ||
207 start == nullptr ||
208 end == nullptr) {
209 return false;
210 }
211 *attribute = NL80211NestedAttr(vector<uint8_t>(start, end));
212 if (!attribute->IsValid()) {
213 return false;
214 }
215 return true;
216 }
217
DebugLog() const218 void NL80211Packet::DebugLog() const {
219 const uint8_t* ptr = data_.data() + NLMSG_HDRLEN + GENL_HDRLEN;
220 const uint8_t* end_ptr = data_.data() + data_.size();
221 while (ptr + NLA_HDRLEN <= end_ptr) {
222 const nlattr* header = reinterpret_cast<const nlattr*>(ptr);
223 if (ptr + NLA_ALIGN(header->nla_len) > end_ptr) {
224 LOG(ERROR) << "broken nl80211 atrribute.";
225 return;
226 }
227 LOG(INFO) << "Have attribute with nla_type=" << header->nla_type
228 << " and nla_len=" << header->nla_len;
229 if (header->nla_len == 0) {
230 LOG(ERROR) << "0 is a bad nla_len";
231 return;
232 }
233 ptr += NLA_ALIGN(header->nla_len);
234 }
235 }
236
237 } // namespace wificond
238 } // namespace android
239