UDP连接始终成功 [英] UDP Connect Always Succeeds
问题描述
我正在使用Boost ASIO通过以太网通过以太网屏蔽连接到Arduino Nano.这是Arduino设置:
I am using Boost ASIO to connect to an Arduino Nano with an Ethernet Shield over ethernet. This is the Arduino setup:
#include <EtherCard.h>
ether.staticSetup("10.0.0.4", "10.0.0.1");
ether.udpServerListenOnPort(&callback_function, 1337);
这是我连接的C ++代码:
This is my C++ code that connects to it:
标题
#include <boost/asio.hpp>
#include <boost/shared_ptr.hpp>
#include <boost/make_shared.hpp>
#include <boost/bind.hpp>
#include <boost/thread.hpp>
#include <boost/system/error_code.hpp>
#include <boost/system/system_error.hpp>
boost::system::error_code error_1;
boost::shared_ptr <boost::asio::io_service> io_service_1;
boost::shared_ptr <boost::asio::ip::udp::socket> socket_1;
初始化
// 1. reset io service
io_service_1.reset();
io_service_1 = boost::make_shared <boost::asio::io_service> ();
// 2. create endpoint
boost::asio::ip::udp::endpoint remote_endpoint(
boost::asio::ip::address::from_string("10.0.0.4"),
1337
);
// 3. reset socket
socket_1.reset(new boost::asio::ip::udp::socket(*io_service_1));
// 4. connect socket
socket_1->async_connect(remote_endpoint, socket_1_connect_callback);
// 5. start io_service_1 run thread after giving it work
boost::thread t(boost::bind(&boost::asio::io_service::run, *&io_service_1));
回调
function socket_1_connect_callback (const boost::system::error_code& error_1)
{
// 1. check for errors
if (error_1)
{
std::cerr << "error_1.message() >> " << error_1.message().c_str() << std::endl;
return;
}
else
{
INFO << "connection succeeded";
}
return;
}
即使Arduino没上电,插座也会每次连接.为什么连接不失败?
The socket connects every time, even if the Arduino is not powered. Why does it not fail to connect?
推荐答案
根据定义,UDP是无连接协议. 连接" UDP套接字只是一种简便的操作,它使您可以在不指定接收者的情况下在该套接字上发送数据报-它使用您提供给连接调用的数据报.
By definition, UDP is connection-less protocol. 'Connecting' a UDP socket is simply a convenience operation, which allows you to than send datagrams on that socket without specifying recipient - it uses the one you gave to a connect call.
但是除此之外,它什么也没做.除非您自己实现请求/响应方案,否则实际上没有任何方法可以检查是否有人在UDP的另一端进行监听.
But other than that, it does nothing. There is really no way to check if someone is listening on the other side of UDP, unless you implement a request/response scheme yourself.
您正在使用Boost.Asio的事实对此基本事实没有任何作用.
The fact that you are using Boost.Asio adds nothing to this basic fact.
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