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 #pragma once 18 19 #include <libnl++/Message.h> 20 21 namespace android::nl { 22 23 /** 24 * In-place message mutator. 25 * 26 * Useful for making small changes (such as adjusting const-sized attributes or struct fields) 27 * efficiently and in-place. However, if you need to rebuild the message (e.g. to modify variable 28 * sized attributes or add/remove them), you need to use MessageFactory instead. 29 */ 30 class MessageMutator { 31 public: 32 /** 33 * Construct message mutator object from editable buffer. 34 */ 35 MessageMutator(nlmsghdr* buffer, size_t totalLen); 36 37 nlmsghdr* operator->() const; 38 operator Buffer<nlmsghdr>() const; 39 40 /** 41 * Read current attribute value. 42 * 43 * \param Read-only attribute buffer. 44 * \returns Attribute value. 45 */ 46 uint64_t read(Buffer<nlattr> attr) const; 47 48 /** 49 * Write new attribute value. 50 * 51 * \param Read-only attribute buffer. 52 * \param val New value to set. 53 */ 54 void write(Buffer<nlattr> attr, uint64_t val) const; 55 56 class iterator { 57 public: 58 iterator(const MessageMutator& container, Buffer<nlmsghdr>::iterator current); 59 60 iterator operator++(); 61 bool operator==(const iterator& other) const; 62 const MessageMutator operator*() const; 63 64 protected: 65 const MessageMutator& mContainer; 66 Buffer<nlmsghdr>::iterator mCurrent; 67 }; 68 iterator begin() const; 69 iterator end() const; 70 71 private: 72 nlmsghdr* mMutableBuffer; 73 size_t mTotalLen; 74 75 Buffer<nlmsghdr> constBuffer() const; 76 MessageMutator fragment(Buffer<nlmsghdr> buf) const; 77 }; 78 79 } // namespace android::nl 80