1 /*
2  * Copyright (C) 2024 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 <memory>
20 #include <vector>
21 
22 #include "types.h"
23 
24 // Historically, adb expects apackets to be transferred over USB with two transfers. One for the
25 // header and one for the payload. This usually translates into two Blocks. Buggy drivers and
26 // "bridges" / IO libs can lead to merged transfers (e.g.: a header and a payload, or a payload
27 // and the next header).
28 // This class is able to read inbound Blocks containing apackets chopped/merged on any boundaries.
29 class APacketReader {
30   public:
31     APacketReader();
32     ~APacketReader() = default;
33 
34     enum AddResult { OK, ERROR };
35     AddResult add_bytes(Block&& block) noexcept;
36 
37     // Returns all packets parsed so far. Upon return, the internal apacket vector is emptied.
38     std::vector<std::unique_ptr<apacket>> get_packets() noexcept;
39 
40     // Clear blocks so we can start parsing the next packet.
41     void prepare_for_next_packet();
42 
43   private:
44     void add_packet(std::unique_ptr<apacket> packet);
45     Block header_{sizeof(amessage)};
46     std::unique_ptr<apacket> packet_;
47 
48     // We keep packets in this internal vector. It is empty after a `get_packets` call.
49     std::vector<std::unique_ptr<apacket>> packets_;
50 };