1 /*
2 * Copyright (c) 2016, The OpenThread Authors.
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 * 3. Neither the name of the copyright holder nor the
13 * names of its contributors may be used to endorse or promote products
14 * derived from this software without specific prior written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
17 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
20 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
21 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
22 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
23 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
24 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
25 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
26 * POSSIBILITY OF SUCH DAMAGE.
27 */
28
29 /**
30 * @file
31 * This file implements common methods for manipulating MLE TLVs.
32 */
33
34 #include "tlvs.hpp"
35
36 #include "common/code_utils.hpp"
37 #include "common/debug.hpp"
38 #include "common/message.hpp"
39
40 namespace ot {
41
GetSize(void) const42 uint32_t Tlv::GetSize(void) const
43 {
44 return IsExtended() ? sizeof(ExtendedTlv) + static_cast<const ExtendedTlv *>(this)->GetLength()
45 : sizeof(Tlv) + GetLength();
46 }
47
GetValue(void)48 uint8_t *Tlv::GetValue(void)
49 {
50 return reinterpret_cast<uint8_t *>(this) + (IsExtended() ? sizeof(ExtendedTlv) : sizeof(Tlv));
51 }
52
GetValue(void) const53 const uint8_t *Tlv::GetValue(void) const
54 {
55 return reinterpret_cast<const uint8_t *>(this) + (IsExtended() ? sizeof(ExtendedTlv) : sizeof(Tlv));
56 }
57
AppendTo(Message & aMessage) const58 Error Tlv::AppendTo(Message &aMessage) const
59 {
60 return aMessage.AppendBytes(this, static_cast<uint16_t>(GetSize()));
61 }
62
FindTlv(const Message & aMessage,uint8_t aType,uint16_t aMaxSize,Tlv & aTlv)63 Error Tlv::FindTlv(const Message &aMessage, uint8_t aType, uint16_t aMaxSize, Tlv &aTlv)
64 {
65 Error error;
66 uint16_t offset;
67 uint16_t size;
68
69 SuccessOrExit(error = Find(aMessage, aType, &offset, &size, nullptr));
70
71 if (aMaxSize > size)
72 {
73 aMaxSize = size;
74 }
75
76 aMessage.ReadBytes(offset, &aTlv, aMaxSize);
77
78 exit:
79 return error;
80 }
81
FindTlvOffset(const Message & aMessage,uint8_t aType,uint16_t & aOffset)82 Error Tlv::FindTlvOffset(const Message &aMessage, uint8_t aType, uint16_t &aOffset)
83 {
84 return Find(aMessage, aType, &aOffset, nullptr, nullptr);
85 }
86
FindTlvValueOffset(const Message & aMessage,uint8_t aType,uint16_t & aValueOffset,uint16_t & aLength)87 Error Tlv::FindTlvValueOffset(const Message &aMessage, uint8_t aType, uint16_t &aValueOffset, uint16_t &aLength)
88 {
89 Error error;
90 uint16_t offset;
91 uint16_t size;
92 bool isExtendedTlv;
93
94 SuccessOrExit(error = Find(aMessage, aType, &offset, &size, &isExtendedTlv));
95
96 if (!isExtendedTlv)
97 {
98 aValueOffset = offset + sizeof(Tlv);
99 aLength = size - sizeof(Tlv);
100 }
101 else
102 {
103 aValueOffset = offset + sizeof(ExtendedTlv);
104 aLength = size - sizeof(ExtendedTlv);
105 }
106
107 exit:
108 return error;
109 }
110
Find(const Message & aMessage,uint8_t aType,uint16_t * aOffset,uint16_t * aSize,bool * aIsExtendedTlv)111 Error Tlv::Find(const Message &aMessage, uint8_t aType, uint16_t *aOffset, uint16_t *aSize, bool *aIsExtendedTlv)
112 {
113 // This static method searches within a `aMessage` for a TLV type
114 // `aType` and outputs the TLV offset, size, and whether or not it
115 // is an Extended TLV.
116 //
117 // A `nullptr` pointer can be used for output parameters `aOffset`,
118 // `aSize`, or `aIsExtendedTlv` if the parameter is not required.
119 //
120 // Returns `kErrorNone` when found, otherwise `kErrorNotFound`.
121
122 Error error = kErrorNotFound;
123 uint16_t offset = aMessage.GetOffset();
124 uint16_t remainingLen = aMessage.GetLength();
125 Tlv tlv;
126 uint32_t size;
127
128 VerifyOrExit(offset <= remainingLen);
129 remainingLen -= offset;
130
131 while (true)
132 {
133 SuccessOrExit(aMessage.Read(offset, tlv));
134
135 if (tlv.mLength != kExtendedLength)
136 {
137 size = tlv.GetSize();
138 }
139 else
140 {
141 ExtendedTlv extTlv;
142
143 SuccessOrExit(aMessage.Read(offset, extTlv));
144
145 VerifyOrExit(extTlv.GetLength() <= (remainingLen - sizeof(ExtendedTlv)));
146 size = extTlv.GetSize();
147 }
148
149 VerifyOrExit(size <= remainingLen);
150
151 if (tlv.GetType() == aType)
152 {
153 if (aOffset != nullptr)
154 {
155 *aOffset = offset;
156 }
157
158 if (aSize != nullptr)
159 {
160 *aSize = static_cast<uint16_t>(size);
161 }
162
163 if (aIsExtendedTlv != nullptr)
164 {
165 *aIsExtendedTlv = (tlv.mLength == kExtendedLength);
166 }
167
168 error = kErrorNone;
169 ExitNow();
170 }
171
172 offset += size;
173 remainingLen -= size;
174 }
175
176 exit:
177 return error;
178 }
179
ReadUintTlv(const Message & aMessage,uint16_t aOffset,UintType & aValue)180 template <typename UintType> Error Tlv::ReadUintTlv(const Message &aMessage, uint16_t aOffset, UintType &aValue)
181 {
182 Error error;
183
184 SuccessOrExit(error = ReadTlv(aMessage, aOffset, &aValue, sizeof(aValue)));
185 aValue = Encoding::BigEndian::HostSwap<UintType>(aValue);
186
187 exit:
188 return error;
189 }
190
191 // Explicit instantiations of `ReadUintTlv<>()`
192 template Error Tlv::ReadUintTlv<uint8_t>(const Message &aMessage, uint16_t aOffset, uint8_t &aValue);
193 template Error Tlv::ReadUintTlv<uint16_t>(const Message &aMessage, uint16_t aOffset, uint16_t &aValue);
194 template Error Tlv::ReadUintTlv<uint32_t>(const Message &aMessage, uint16_t aOffset, uint32_t &aValue);
195
ReadTlv(const Message & aMessage,uint16_t aOffset,void * aValue,uint8_t aMinLength)196 Error Tlv::ReadTlv(const Message &aMessage, uint16_t aOffset, void *aValue, uint8_t aMinLength)
197 {
198 Error error = kErrorNone;
199 Tlv tlv;
200
201 SuccessOrExit(error = aMessage.Read(aOffset, tlv));
202 VerifyOrExit(!tlv.IsExtended() && (tlv.GetLength() >= aMinLength), error = kErrorParse);
203 VerifyOrExit(tlv.GetSize() + aOffset <= aMessage.GetLength(), error = kErrorParse);
204
205 aMessage.ReadBytes(aOffset + sizeof(Tlv), aValue, aMinLength);
206
207 exit:
208 return error;
209 }
210
FindUintTlv(const Message & aMessage,uint8_t aType,UintType & aValue)211 template <typename UintType> Error Tlv::FindUintTlv(const Message &aMessage, uint8_t aType, UintType &aValue)
212 {
213 Error error = kErrorNone;
214 uint16_t offset;
215
216 SuccessOrExit(error = FindTlvOffset(aMessage, aType, offset));
217 error = ReadUintTlv<UintType>(aMessage, offset, aValue);
218
219 exit:
220 return error;
221 }
222
223 // Explicit instantiations of `FindUintTlv<>()`
224 template Error Tlv::FindUintTlv<uint8_t>(const Message &aMessage, uint8_t aType, uint8_t &aValue);
225 template Error Tlv::FindUintTlv<uint16_t>(const Message &aMessage, uint8_t aType, uint16_t &aValue);
226 template Error Tlv::FindUintTlv<uint32_t>(const Message &aMessage, uint8_t aType, uint32_t &aValue);
227
FindTlv(const Message & aMessage,uint8_t aType,void * aValue,uint8_t aLength)228 Error Tlv::FindTlv(const Message &aMessage, uint8_t aType, void *aValue, uint8_t aLength)
229 {
230 Error error;
231 uint16_t offset;
232 uint16_t length;
233
234 SuccessOrExit(error = FindTlvValueOffset(aMessage, aType, offset, length));
235 VerifyOrExit(length >= aLength, error = kErrorParse);
236 aMessage.ReadBytes(offset, aValue, aLength);
237
238 exit:
239 return error;
240 }
241
AppendUintTlv(Message & aMessage,uint8_t aType,UintType aValue)242 template <typename UintType> Error Tlv::AppendUintTlv(Message &aMessage, uint8_t aType, UintType aValue)
243 {
244 UintType value = Encoding::BigEndian::HostSwap<UintType>(aValue);
245
246 return AppendTlv(aMessage, aType, &value, sizeof(UintType));
247 }
248
249 // Explicit instantiations of `AppendUintTlv<>()`
250 template Error Tlv::AppendUintTlv<uint8_t>(Message &aMessage, uint8_t aType, uint8_t aValue);
251 template Error Tlv::AppendUintTlv<uint16_t>(Message &aMessage, uint8_t aType, uint16_t aValue);
252 template Error Tlv::AppendUintTlv<uint32_t>(Message &aMessage, uint8_t aType, uint32_t aValue);
253
AppendTlv(Message & aMessage,uint8_t aType,const void * aValue,uint8_t aLength)254 Error Tlv::AppendTlv(Message &aMessage, uint8_t aType, const void *aValue, uint8_t aLength)
255 {
256 Error error = kErrorNone;
257 Tlv tlv;
258
259 OT_ASSERT(aLength <= Tlv::kBaseTlvMaxLength);
260
261 tlv.SetType(aType);
262 tlv.SetLength(aLength);
263 SuccessOrExit(error = aMessage.Append(tlv));
264
265 VerifyOrExit(aLength > 0);
266 error = aMessage.AppendBytes(aValue, aLength);
267
268 exit:
269 return error;
270 }
271
272 } // namespace ot
273
