Re: [Boost-users] [asio] SSL async_shutdown() never finishes if called when async_read_some() is in progress

Subject: Re: [Boost-users] [asio] SSL async_shutdown() never finishes if called when async_read_some() is in progress
From: Franz Fehringer (fehrin2_at_[hidden])
Date: 2018-04-06 14:49:48

It's Boris Karloff but Chris(topher) Kohlhoff :-)

Am 06.04.2018 um 16:37 schrieb Richard Hodges via Boost-users:
>
>
> On 6 April 2018 at 16:29, Alexander D. via Boost-users
> <boost-users_at_[hidden] <mailto:boost-users_at_[hidden]>> wrote:
>
>     On April 6, 2018 9:55 PM, Vinnie Falco via Boost-users
>     <boost-users_at_[hidden] <mailto:boost-users_at_[hidden]>>
>     wrote:
>     > On Fri, Apr 6, 2018 at 6:11 AM, Alexander D. via Boost-users
>     > <boost-users_at_[hidden]
>     <mailto:boost-users_at_[hidden]>> wrote:
>     >>>> The only solution I can think of would be to cancel the read
>     operation, but there's no portable way in asio to do this.
>     >>>
>     >>>Â  Â  Â sock.next_layer().cancel();
>     >>>
>     >>> ?
>     >>
>     >> Per ASIO Reference:
>     >>
>     >> "Calls to cancel() will always fail with
>     boost::asio::error::operation_not_supported when run on Windows
>     XP, Windows Server 2003, and earlier versions of Windows, unless
>     BOOST_ASIO_ENABLE_CANCELIO is defined. However, the CancelIo
>     function has two issues that should be considered before enabling
>     its use:
>     >> ..."
>     >>
>     >> which renders cancel() non-portable.
>     >
>     > I consider the issues with cancel present in Windows XP and Windows
>     > Server 2003 to be sufficiently problematic that it is not worth
>     taking
>     > them into account when designing robust network applications (I do
>     > develop mostly on Windows). Unless you have a specific business need
>     > to support those defective operating systems, I would just ignore
>     > them.
>
>     Yes, I do need the program to work on at least Windows XP.
>
>     However, even if cancel() is used, it is a workaround, not a
>     solution. If you run the code I supplied, you'll notice that
>     async_read_some() is actually finished with a "stream truncated"
>     error, quite similar to "canceling" the read. The problem is on
>     async_shutdown()'s handler not being called, and it's not
>     mentioned anywhere in the reference. Why can't we shutdown a
>     stream while reading from it (since we can close a socket while
>     reading)?
>
>
> In the past, when I have had queries about the inner workings and
> design decisions behind ASIO, I have emailed the author, Chris
> Karloff. I am sure he is a busy guy but he has taken the trouble to
> answer helpfully in the past. It may be worth dropping him a line and
> asking for a suggestion.
>
> He didn't charge me but having received help twice now, I think it
> would be rude of me not to offer him a few hours consultancy if I
> needed his help again. 
>
> https://think-async.com/Asio/CommercialSupport
>
>
>
> Â 
>
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