如何检测同一局域网中的PC是否断开连接?温索克，Icmp? [英] How do i detect if a PC on the same lan disconnects? Winsock,Icmp?
问题描述
你好，
我正在编写一个C ++控制台应用程序，该应用程序经常应检测同一局域网上的PC是否仍处于连接状态.我有这种情况:
家庭局域网(3个，1个路由器)
客户-------路由器------- PC
我的应用程序在客户端上运行，它应该检测PC是否无法访问(例如，关闭计算机或断开电缆连接).
我有一些代码可以做到:
Hello there,
i''m coding a C++ console application that, very often, should detect if a PC on the same lan is still connected. I have this kind of situation:
HOME LAN (3pc, 1 router)
CLIENT ------- ROUTER ------- PC
My application, runs on the client and it should detect if the PC becomes unreachable (for example is shut down, or the cable is disconnected).
I have some code that does:
while(true){
If(!PCisConnected())
//Do Something and close app;
Sleep(1000);
}
在这一点上，我需要对PcISConnected()函数进行编码.检测断开连接的最佳和最经济的方法是什么?
更确切地说，该PC并不是真正的PC，而是可以响应PING(ICMP ECHO)且具有Web服务器+ Ftp服务器的LAN UNIT.因此，基本上，它们可以检测到ICMP或TCP 80/21断开连接的方式.
我的第一个尝试在此LAN环境中并不是很好，而在WAN环境中却非常出色.
我创建了一个无限循环，在其中创建了一个用于端口80的TCP套接字并调用connect()函数.
它的运行效果很好，但是:如果PC断开连接，则平均需要20到30秒才能引发错误(如果PC是世界上某个地方的Web服务器，则运行得很好).
我的第二次尝试有一个类似的问题:
而不是将connect()陷入无限循环，我将send()放入.
因此，我尝试将消息发送到PC.
问题是，即使我断开了PC与LAN的连接，发送迭代10-20次也将引发错误.因此，大约20次，它说即使PC断开连接也成功发送了该消息(就像我之前说的那样，在世界各地使用Web服务器进行的相同测试非常有效，并且发送仅重复了2次，然后抛出错误). br/>
第三次尝试是ICMP，但我没有为我的项目找到任何合适的解决方案(通过Eclipse进行编码).但是我发现ICMP负担得起，因为有时，即使主机启动了，ping也会失败，并且该故障会导致应用程序出现故障，导致主机仍然启动.
我该如何解决这个问题?我在这里可以采取的最佳方法是什么?
它应该可以负担得起，而且速度很快，因为我应该在2-3秒内检测到断开连接，而不再是其他原因.
我知道，我需要不断地向PC发送消息，但这不是问题.
谢谢大家.
At this point i need to code the PcISConnected() function. What''s the best and the most affordable way to detect if it disconnects?
To be more precise, the PC is not a real PC but rather a LAN UNIT that can reply to PING (ICMP ECHO) and that has a Web Server + Ftp Server. So basically they way i can detect a disconnection is trough ICMP or TCP 80/21.
My 1st attempt weren''t so good in this LAN environment while they''re very great in an WAN environment.
I created an infinite loop in which i create a TCP Socket to the port 80 and call the connect() function.
It worked great BUT: if the PC is disconnected, it tooks an average 20-30seconds before throwing an error (while it worked very well if the PC was a webserver in the world, somewhere).
My 2nd attempt has a similiar issue:
Instead of putting the connect() in an infinite loop, i put the send().
So i''ve tryied to send a message to the PC.
The issue is that, even if i disconnect the PC from the LAN, the send iterate 10-20 times before throwing an error. So for around 20times, it says that the message was succesfully sent even if the PC is disconnected (as i said before, the same test with a webserver around the worl, worked great and the send iterated only 2times before throwing an error).
And the 3rd attempt is ICMP but i didn''t found any suitable solution for my project (which is being coded trough Eclipse). But i found ICMP not so affordable since sometimes, a ping fails even if the host is up and that failure will lead application to malfunction cause the host is still up.
How can i solve this issue? What''s the best approach i can take here?
It should be affordable and fast as i should detect a disconnection in 2-3 seconds, no more.
I know for that, i need to continuosly send message to the PC, but that''s not an issue.
Thanks you all.
推荐答案
我宁愿在单独的线程中定期ping PC.您将需要使用ICMP协议的实现，请参见 http://en.wikipedia.org/wiki/Ping [ ^ ].
—SA
I would rather ping the PC periodically, in a separate thread. You will need to use implementation of ICMP protocol, see http://en.wikipedia.org/wiki/Ping[^].
—SA
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