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

...

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.

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.