[gnutls-help] 2.x 3.x API compatibility

[Nikos Mavrogiannopoulos]

On Mon, Mar 31, 2014 at 6:00 PM, MK <mk at cognitivedissonance.ca> wrote:
> I've been developing an application which uses GnuTLS  against 3.x
> versions.   However, on one of my target platforms the last version
> which builds successfully is 3.0.x -- I'm looking into this further
> today, but it is small ARM device so checking builds is slow (the
> problem was previously reported WRT to 3.2 by someone else,
> http://lists.gnutls.org/pipermail/gnutls-help/2013-December/003288.html
> ).

Hello,
 You are linking with an older libnettle than the one required.

> I.e., I can't use the latest 3.2 which includes the fix for Advisory
> GNUTLS-SA-2014-2, so I must fall back on the git version of
> 2.12.
>
> I have a recollection from when I began this several years ago
> regarding backward compatibility issues with 3.x, but it seems
> that according to this:
>
> http://upstream-tracker.org/versions/gnutls.html
>
> Going back to 2.12 should be okay.  Is that correct?
> I realized after sending the last email it might seem I am talking
> about forward compatibility, and maybe I am depending on how I proceed
> (but I don't expect anyone else to be concerned with the issue in that
> case).

A program developed for 2.12.x will be forward compatible with 3.x, for any x
now. However, you'll have to use much more verbose code for common cases,
and you can see that by comparing the simple examples in the documentation.
As code base GnuTLS 2.12.x is unsupported though.

regards,
Nikos