Date: Wed, 31 Jan 2007 15:04:57 -0500 (EST) From: Garrett Wollman <wollman@khavrinen.csail.mit.edu> To: freebsd@j-davis.com Cc: freebsd-net@freebsd.org, freebsd-stable@freebsd.org Subject: Re: send() returns error even though data is sent, TCP connection still alive Message-ID: <200701312004.l0VK4vXC066309@khavrinen.csail.mit.edu> In-Reply-To: <1170269163.22436.71.camel@dogma.v10.wvs>
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In article <1170269163.22436.71.camel@dogma.v10.wvs>, Jeff Davis <freebsd@j-davis.com> wrote: >You should see something like "write failed: host is down" and the >session will terminate. Of course, when ssh exits, the TCP connection >closes. The only way to see that it's still open and active is by >writing (or using) an application that ignores EHOSTDOWN errors from >write(). I agree that it's a bug. The only time write() on a stream socket should return the asynchronous error[1] is when the connection has been (or is in the process of being) torn down as a result of a subsequent timeout. POSIX says "may fail" for these errors write() and send() on sockets -GAWollman [1] There are two kinds of error returns in the socket model: synchronous errors, like synchronous signals, are attributed to the result of a specific system call, detected prior to syscall return, and usually represent programming or user error (e.g., attempting to connect() on an fd that is not a socket). Asynchronous errors are detected asynchronously, and merely posted to the socket without being delivered; they may be delivered on the next socket operation. See XSH 2.10.10, "Pending Error".
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