Hi all, how do I detect when a client disconnects (normally or abnormally) from my server? I''m kindda new to this send, receive, accept thing... Thanx,

[Hugo Ferreira][Positronic Dreams][Stick Soldiers]
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[Hugo Ferreira][Positronic Dreams][Stick Soldiers]
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If you are using asynchronous sockets you can check for the FD_CLOSE message (it will come in the WM_USER+something message - whatever you defined it to be). The message will come with a Connection Reset By Peer error if the disconnect was abnormal. There are some good tutorials on GameDev about this in the articles section.

Firebird Entertainment

Im using normal bloking sockets, with threads...

[Hugo Ferreira][Positronic Dreams][Stick Soldiers]
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Im using normal bloking sockets, with threads...

[Hugo Ferreira][Positronic Dreams][Stick Soldiers]
"Please Review my WebSite!".

One way that''s done is to send a special PING message every so often (90 seconds is a commonly used number). The client then responds with a PONG message. If you''re reading to send out the next PING to a client, but they never responded to the last PING, you can assume they are disconnected.

- Andy Oxfeld

This is off the top of my head (I haven''t used winsock in a while), but I believe you can check the return value of a call to read(). I think a socket tells you there is data to read, and then when you actually read it read() returns either 0 or something less than 0, and that means the client was disconnected. Sorry to be so vague, but look up read in MSDN and play around with it.

That''s correct Anthracks.

recv() returns 0 if the socket has been disconnected normally, or < 0 (SOCKET_ERROR) if disconnected abnormally (/other error). If the number is greater than zero, then the recv was successful.

Another thing to check is select(). Use select to determine if you should read a socket or not - if a disconnection has taken place, then select() will tell you that you should read the socket (via recv()) and you''ll discover the disconnection when recv returns <= 0.

Hope that helps.

Tom l

What would shutdown(Socket, parameter) do?

Would this trigger a SOCKET_ERROR with WSAGetLastError() = WSAESHUTDOWN ?

and what is this graceful or unexcpected?

what would be the best way of gracefully close a client socket?
say bye to the server and call what?

thanks

It depends on the "linger" option of the client socket. Generally, calling shutdown will initiate a graceful shutdown. But if you set the "linger" option to 0, it''ll do an ungraceful shutdown and recv will return < 0. You''d also get an ungraceful shutdown if, for example, you pulled the network cable out of the socket.

WSAESHUTDOWN is only returned if you call shutudown on you own socket, so if you did something like this:

recv( s, buffer, numbytes, 0 ); // this one is OK
shutdown( s, FD_RECEIVE );
recv( s, buffer, numbytes, 0 ); // this would return WSAESHUTDOWN

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