Re: [Boost-users] ASIO ssl::stream read/write_some question.

From: Derrick Hathaway (d.hathaway_at_[hidden])
Date: 2008-02-26 23:40:51

On 2/26/08, Eugene M. Kim <gene_at_[hidden]> wrote:
>
> Derrick Hathaway wrote:
> > Could someone please shed some light on ASIO SSL reads and writes for
> > me? The names of the read and write functions for the ssl::stream
> > (read_some and write_some) imply to me that the buffer(s) may not be
> > completely filled/sent with a read/write. Do I need to have some
> > intermediate handler that will begin another async_read/write_some
> > until my buffer is filled/flushed? The documentation doesn't seem to
> > indicate that this is necessary. It makes sense from the example that
> > the reads may not fill the provided buffer before invoking the
> > handler. So it may be necessary to call read_some multiple times until
> > the expected number of bytes is received. But is this also the case
> > with writes, and if so, how do I manage multiple writes if I provide a
> > vector of buffers to be written with and async_write_some?
>
> I have no authority to give a definite answer, but my experience with it
> indicates that what you assume is indeed right.  All
> read_some/write_some methods may read or write fewer bytes than
> requested, and you need to check the num_transferred placeholder and
> invoke read_some/write_some again as necessary.
>
> I remember seeing an adapter method that does this for you in some other
> class, but I forgot exactly where it is (didn't need/want to use it in
> my program).
>
> Cheers,
>
> Eugene
>
>
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>
Thanks for your reply, Eugene. I guess I just didn't read the documentation
and or experiment enough. I naively assumed that it had to be done the way
the example SSL code does it (by calling ssl socket's async_read/write_some
methods). I didn't know that boost::asio::async_read/write could be called
with an ssl_stream, which according to documentation will read or write
until an error occurs or the provided buffer(s) are filled/written.

Derrick