通过boost异步发送和接收自定义数据包？ [英] Async sending and receiving custom data packets with boost?
问题描述
我正在尝试通过boost异步发送和接收自定义数据包，基于当前的实现，我有一些疑问：
I am trying to asynchronously send and receive custom data packets with boost and I have some questions, based on my current implementation:
tcpclient.cpp
#include "tcpclient.h"
#include <boost/chrono.hpp>
#include "../utils/logger.h"
tcpclient::tcpclient(std::string host, int port) :
_endpoint(boost::asio::ip::address::from_string(host), port), _socket(_ioservice) {
logger::log_info("Initiating client ...");
}
void tcpclient::start() {
connect();
_ioservice.run();
}
void tcpclient::connect() {
_socket.async_connect(_endpoint, std::bind(&tcpclient::connect_handler, this, std::placeholders::_1));
}
void tcpclient::receive() {
boost::asio::async_read(_socket, boost::asio::buffer(data, HEADER_LEN), std::bind(&tcpclient::read_handler, this, std::placeholders::_1));
}
void tcpclient::connect_handler(const boost::system::error_code &error) {
if (!error) {
_status = CONNECTED;
logger::log_info("Connected to " + get_remote_address_string());
receive();
} else {
_status = NOT_CONNECTED;
_socket.close();
_timer.expires_from_now(boost::asio::chrono::seconds{2});
_timer.async_wait(std::bind(&tcpclient::reconnect_handler, this, std::placeholders::_1));
logger::log_info("Failed to connect");
}
}
void tcpclient::reconnect_handler(const boost::system::error_code &error) {
connect();
}
void tcpclient::read_handler(const boost::system::error_code& error, std::size_t bytes_transferred)
{
logger::log_info("reading some data?");
}
std::string tcpclient::get_remote_address_string() {
return _socket.remote_endpoint().address().to_string() + ":" + std::to_string(_socket.remote_endpoint().port());
}
tcpclient.h
#include <string>
#include <boost/asio.hpp>
enum ConnectionStatus{
NOT_CONNECTED,
CONNECTED
};
class tcpclient {
public:
tcpclient(std::string host, int port);
void start();
void connect();
private:
ConnectionStatus _status = NOT_CONNECTED;
const int HEADER_LEN = 0x01;
void receive();
void connect_handler(const boost::system::error_code& error);
void reconnect_handler(const boost::system::error_code &error);
void read_handler(const boost::system::error_code& error);
std::string get_remote_address_string();
boost::asio::io_service _ioservice;
boost::asio::ip::tcp::endpoint _endpoint;
boost::asio::ip::tcp::socket _socket;
boost::asio::steady_timer _timer{_ioservice, boost::asio::chrono::seconds{2}};
};
1）添加两个用于读写的单独的处理程序是否有意义，一个用于标题，一个为了身体？
1) Would it make sense to add two seperate handlers for reading and writing, one for the header one for the body?
2）如何确保可以同时发送和接收数据而不会遇到任何问题？这需要多个插座吗？通常如何实现这种功能？
2) How can I ensure that I can send and receive data at the same time without running into any issues? Does this require multiple sockets? How is such functionality usually implemented?
3）我将如何发送自定义数据结构？我想实现一个自定义的数据包结构。我将如何发送此类对象，boost是否具有内置的串行器？
3) How would I go sending custom data structures? I want to implement a custom packet structure. How would I sent such objects, does boost have an inbuilt serializer? How or custom data structures sent and received?
4）如果在发送或接收数据期间连接断开，会发生什么情况？通过检查eof的错误代码对象是否可以在接收/发送处理程序中直接处理此类异常？
4) What happens if the connection drops during sending or receiving data? Are such exceptions handled directly in the receive/send handlers by checking the errorcode object for eof?
一个基本示例将大有帮助！
A basic example for that would help a lot!
推荐答案
1）添加两个用于读写的单独处理程序是否有意义，一个用于正文，一个用于标题？ >
是的。代码不同，最佳处理程序是最佳实践。
Yes. Code is different, different handlers is best practice.
2）如何确保我可以同时发送和接收数据而不会遇到任何问题？
异步操作。函数会立即返回，因此唯一的延迟就是网络速度。
Async operations. The functions return immediately, so the only delay is the network speed.
3）我将如何发送自定义数据结构？
boost :: asio :: buffer 支持发送/接收原始内存字节。当这还不够时，asio会进行序列化：
boost::asio::buffer supports sending/receiving raw memory bytes. When this isn't enough, asio has serialization:
- https://www.boost.org/doc/libs/1_70_0/libs/serialization/doc/index.html
- https ：//www.boost.org/doc/libs/1_70_0/libs/serialization/example/demo.cpp
- https://www.boost.org/doc/libs/1_70_0/libs/serialization/doc/index.html
- https://www.boost.org/doc/libs/1_70_0/libs/serialization/example/demo.cpp
4）如果在发送或接收数据期间连接断开，会发生什么？
所有读写操作都返回 boost :: system :: error_code 。如果发生错误，则必须关闭插座（并在可能的情况下再次连接）。一些基本代码：
All read and write operations return a boost::system::error_code. If an error occurs, the socket must be closed (and connected again if possible). Some basic code:
void AfterReadingHeader(const boost::system::error_code & aError)
{
if (aError)
{
// something went wrong
boost::system::error_code error;
socket.shutdown(tcp::socket::shutdown_receive, error);
socket.close(error);
}
...
}
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