Graceful and Ungraceful Socket Disconnects

PyroBoy · 2002-03-07T22:20:51

I''m having a problem recognising graceful and ungraceful disconnects on the client side. It''s a bit involved, so bear with me... What I''m mainly dealing with is the return value of recv() and its relationship to socket disconnection. For recv(), The docs say that a positive return value means that that number of bytes of data came through. A return value of 0 indicates the socket was disconnected gracefully on the other end and a negative return value indicates an error (as would happen in an ungraceful disconnect). When one side wants to disconnect, it calls closesocket() on the connected socket, and the other end''s recv() (in theory) returns 0 and the disconnected app can be notified that the other side has closed the connection gracefully. When the connection goes down for any other reason, recv() (again, in theory) returns a negative value on both sides of the connection and both sides are notified of a crash-n-burn style disconnect. Now, this setup works great on the server side - when the client closes its socket, recv() returns 0 on the server side, and when the client is closed down hard(ctrl-alt-del it out of existance without calling closesocket()), recv() returns a negative value indicating the client went down unexpectedly. But the exact same process (run by the exact same code - it''s encapsulated in a connection class) initiated from the *server* side malfunctions. When the server closes its sockets gracefully, the recv() call on the client side returns -1, indicating an error (ungraceful disconnect). When the server is shut down ungracefully, recv() still returns -1 on the client side. Why would graceful disconnects via the 0 return value of recv() work one way and not the other? Does the meaning of the return value of recv() depend on whether it''s the client or server side calling it? The docs don''t seem to think so... Should I be doing more to initiate a disconnection than simply calling closesocket()?

Networking and Multiplayer Programming

Started by PyroBoy February 09, 2002 12:27 AM

19 comments, last by PyroBoy 22 years, 11 months ago

PyroBoy

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March 07, 2002 10:20 PM

Yeah that''s how I was planning to do it originally. Then I did a little reading and found out that facilities are already in place to detect closing connections. Or so I thought.

Graceful and Ungraceful Socket Disconnects

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Graceful and Ungraceful Socket Disconnects

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