[openssl-dev] [openssl.org #4119] DTLS resets handshake hash too frequently for ClientHello

[David Benjamin via RT]

On Tue, Nov 3, 2015 at 12:42 PM David Benjamin <davidben at google.com> wrote:

> I'm not sure that fix quite works though. If BIO_flush completes
> asynchronously (hrm, it's missing an rwstate update), then I believe you'll
> be in a state where you *do* want to repeat the init_off / init_num adjust.
> You might be able to get away with using init_off/init_num with some minor
> tweaks? Another problem: because the fragment headers clobber whatever was
> already written, msg_callback sees garbage. Also this function is used for
> the unfragmented ChangeCipherSpec, so it's even messier.
>
> I dunno, this code is too stateful by several orders of magnitude. I think
> I'm going to toy with rewriting it now rather than think too hard about the
> existing mess.
>

This still needs to be reviewed, but here's a go at a cleaner version on
our end. It passes our test suite, even after modifying it to stress the
async write + low MTU case. (And the old code indeed does not.)

https://boringssl-review.googlesource.com/#/c/6420/
https://boringssl-review.googlesource.com/#/c/6421/

David