1 /*
2 * Copyright (C) 2020 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 <libnl++/MessageMutator.h>
18
19 namespace android::nl {
20
MessageMutator(nlmsghdr * buffer,size_t totalLen)21 MessageMutator::MessageMutator(nlmsghdr* buffer, size_t totalLen)
22 : mConstBuffer(buffer, totalLen), mMutableBuffer(buffer) {
23 CHECK(totalLen >= sizeof(nlmsghdr));
24 }
25
operator ->() const26 nlmsghdr* MessageMutator::operator->() const {
27 return mMutableBuffer;
28 }
29
30 MessageMutator::operator Buffer<nlmsghdr>() const {
31 return mConstBuffer;
32 }
33
read(Buffer<nlattr> attr) const34 uint64_t MessageMutator::read(Buffer<nlattr> attr) const {
35 return attr.data<uint64_t>().copyFirst();
36 }
37
write(Buffer<nlattr> attr,uint64_t val) const38 void MessageMutator::write(Buffer<nlattr> attr, uint64_t val) const {
39 const auto attrData = attr.data<uint64_t>();
40 const auto offset = mConstBuffer.getOffset(attrData);
41 CHECK(offset.has_value()) << "Trying to write attribute that's not a member of this message";
42
43 const auto writeableBuffer = reinterpret_cast<uint8_t*>(mMutableBuffer) + *offset;
44 const auto attrSize = attrData.getRaw().len();
45
46 if (attrSize > sizeof(val)) memset(writeableBuffer, 0, attrSize);
47 memcpy(writeableBuffer, &val, std::min(sizeof(val), attrSize));
48 }
49
50 } // namespace android::nl
51