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To: Yuyi Wang <Strawberry_Str AT hotmail DOT com>
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Subject: RE: [EXTERNAL] Re: unix socket hang when connect
Thread-Topic: [EXTERNAL] Re: unix socket hang when connect
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From: "Lavrentiev, Anton \(NIH/NLM/NCBI\) \[C\] via Cygwin" <cygwin AT cygwin DOT com>
Reply-To: "Lavrentiev, Anton \(NIH/NLM/NCBI\) \[C\]" <lavr AT ncbi DOT nlm DOT nih DOT gov>
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Sender: "Cygwin" <cygwin-bounces~archive-cygwin=delorie DOT com AT cygwin DOT com>

> I'm agree with you, but on other *nix platforms, and even on Windows with
> winsock and AF_UNIX, connect() doesn't wait for accept(). I would like such
> behavior.

The behavior that connect() does not require accept() from the other end is platform-specific.
It's your other system's courtesy, actually, to acknowledge the connection before the user code calls accept().  But it is not guaranteed.

> setting SO_PEERCRED on the client socket works.

This is again a kludge, which is not designed (in general of what SO_PEERCRED is supposed to do) to address the situation above.  Yes, it makes it work, in this particular case on this particular platform (Cygwin), but it won't have the same effect on some other Unix platform that wants to get accept() in the user code and that doesn't ack the connection without it, otherwise.

$.02,

Anton Lavrentiev
Contractor NIH/NLM/NCBI


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