[网络协议]流式包处理，c++，粘包，半包，tcp

.cpp

bool NetworkManager::handle_data(TArray<uint8>& received_data, int _byte_cnt)
	{
		uint32_t handled_offset = 0;
		while (handled_offset != _byte_cnt)
		{
			auto byte_cnt_left = _byte_cnt - handled_offset;
			//头上一次未接收全
			if (data_handle_record.head_rec_cnt < DataHandleRecord::Data_Head_Size)
			{
				//头本次还是未收全
				if (byte_cnt_left + data_handle_record.head_rec_cnt < DataHandleRecord::Data_Head_Size)
				{
					memcpy(data_handle_record.get_head_write_pos(),
						received_data.GetData(),
						//接收大小
						byte_cnt_left);
					data_handle_record.head_rec_cnt += byte_cnt_left;

					return true;
					//return false;
				}
				//头本次收全
				else
				{
					handled_offset += DataHandleRecord::Data_Head_Size - data_handle_record.head_rec_cnt;

					memcpy(data_handle_record.get_head_write_pos(),
						received_data.GetData(),
						//剩余大小
						DataHandleRecord::Data_Head_Size - data_handle_record.head_rec_cnt);
					data_handle_record.head_rec_cnt = DataHandleRecord::Data_Head_Size;

					data_handle_record.update_body_buff_size();
					//准备好vector空间
					continue;
				}

			}
			//处理body pack
			// 1.剩余数据小于需要读的包数量(不够
			if (byte_cnt_left < data_handle_record.pack_head.pack_len -
				data_handle_record.body_rec_cnt)
			{
				//memcpy(data_handle_record,)
				data_handle_record.write_data_2_body(received_data.GetData(), byte_cnt_left);
				handled_offset += byte_cnt_left;
			}
			else
				//完成读包
			{
				auto len = data_handle_record.pack_head.pack_len -
					data_handle_record.body_rec_cnt;
				data_handle_record.write_data_2_body(received_data.GetData(), len);
				handled_offset += len;

				//处理包
				// ...

				//重置状态
				data_handle_record.reset();
			}
		}
		//根据
		return true;
	}

.h

struct PackHead
	{
		uint8_t pack_id;
		uint32_t pack_len;

	};
	//};
	struct DataHandleRecord
	{
		static const uint8_t Data_Head_Size = 5;
		PackHead pack_head;
		uint8_t head_rec_cnt = 0;
		std::vector<uint8_t> body_buff;
		uint32_t body_rec_cnt = 0;

		//接受完头后就调用
		void update_body_buff_size()
		{
			//只增不减
			if (body_buff.size() < pack_head.pack_len)
			{
				body_buff.resize(pack_head.pack_len);
			}
		}
		void reset()
		{
			head_rec_cnt = 0;
			body_rec_cnt = 0;
			//body_data.resize(0);// = 0;
		}
		void* get_head_write_pos()
		{
			return static_cast<void*>(&pack_head + head_rec_cnt);
		}
		void* write_data_2_body(const void* src, uint32_t len)
		{
			memcpy(&body_buff + len, src, len);
			body_rec_cnt += len;
		}
	};