Re: Ncat/Nsock notification of connection reset

[Frank Bergmann <nmap () tuxad com>]

On Fri, Mar 17, 2017 at 11:41:34PM -0500, Daniel Miller wrote:
>    I really think there ought to be some way to catch the fact that the server
>    has killed the connection. The first step would be making sure Nsock notices
>    this. With the default select engine [2], I don't see any indication of the
>    event with strace. But with the epoll engine, I think I see something that
>    looks like this:
>    epoll_wait(3, {{EPOLLERR|EPOLLHUP, {u32=13173952, u64=13173952}}}, 128, -1)
>    = 1

Hi Daniel,

ucspi-ssl had a long time issue causing high load when the *client*
connection was resetted because a fast loop of poll() (not epoll) and
read() did happen.

Here the issues was that on connection reset poll() delivered an "IN" event
but the read() after it only delivered 0 bytes / EOF. The fix HERE was to
just check for 0 bytes after IN. Erwin Hoffmann applied my proposed patch
for 0.98. (I detected the issue on linux i386 and x86_64.)

More information I found here:
https://sourceware.org/bugzilla/show_bug.cgi?id=13660

Frank


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