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101 lines
3.4 KiB
101 lines
3.4 KiB
4 months ago
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/*
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* Copyright 2018 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#pragma once
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#include <cstdint>
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#include <memory>
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#include <type_traits>
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#include <utility>
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#include <vector>
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namespace bluetooth {
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// Abstract base class that is subclassed to provide type-specifc accessors on
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// data. Manages said data's memory and guarantees the data's persistence. Once
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// created the underlying data is immutable.
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class Packet : public std::enable_shared_from_this<Packet> {
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friend class Iterator;
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friend class PacketBuilder;
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public:
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virtual ~Packet() = default;
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protected:
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Packet()
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: packet_start_index_(0),
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packet_end_index_(0),
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data_(std::make_shared<std::vector<uint8_t>>(0)){};
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Packet(std::shared_ptr<const Packet> pkt, size_t start, size_t end)
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: packet_start_index_(start), packet_end_index_(end), data_(pkt->data_){};
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Packet(std::shared_ptr<const Packet> pkt) : data_(pkt->data_) {
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auto indices = pkt->GetPayloadIndecies();
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packet_start_index_ = indices.first;
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packet_end_index_ = indices.second;
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};
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public:
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size_t size() const;
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class Iterator begin() const;
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class Iterator end() const;
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uint8_t operator[](size_t i);
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// Check to see if the packet is structured correctly and have the correct
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// lengths. Data access on an invalid packet may cause a crash.
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virtual bool IsValid() const = 0;
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// Debug string representation of the packet
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virtual std::string ToString() const = 0;
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// Convert a packet horizontally in a layer, you may only specialize
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// into a more specific type and doing otherwise will cause a compiler error
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//
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// Example:
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// std::shared_ptr<AvrcpPacket> base;
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// std::shared_ptr<AvrcpVendorPacket> p =
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// Packet::Specialize<AvrcpVendorPacket>(base);
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template <class T, class U>
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static std::shared_ptr<T> Specialize(const std::shared_ptr<U>& pkt) {
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static_assert(std::is_convertible<U*, Packet*>::value,
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"Unable to specialize a non-packet object.");
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static_assert(std::is_convertible<T*, Packet*>::value,
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"Unable to specialize to something that isn't a packet");
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static_assert(std::is_convertible<T*, U*>::value,
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"Can not convert between the two packet types.");
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return std::shared_ptr<T>(
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new T(pkt, pkt->packet_start_index_, pkt->packet_end_index_));
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};
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protected:
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// Packet should be immutable other than when building
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size_t packet_start_index_;
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size_t packet_end_index_;
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std::shared_ptr<std::vector<uint8_t>> data_;
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private:
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// Only Available to the iterators
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virtual size_t get_length() const;
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virtual uint8_t get_at_index(size_t index) const;
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// Returns the begining and end indicies of the payload of the packet.
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// Used when constructing a packet from another packet when moving
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// between layers.
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virtual std::pair<size_t, size_t> GetPayloadIndecies() const = 0;
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};
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} // namespace bluetooth
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