need function to retrieve subject alternative names

[Ludwig Nussel]

a function to retrieve a certificate's subject alternative names is
missing. That's needed for any client that wants to implement proper
certificate checks though.

The attached patch adds the function crypto.get_subjectAltNames()
for that purpose.

[Jean-Paul Calderone (exarkun)]

Hi Ludwig,

Thanks for the patch. This looks like it may overlap with the work that Roland Hedberg did in the lp:~roland-hedberg/pyopenssl/devel branch. Unfortunately it seems a ticket was never opened to correspond to that work. Can you compare what's there with what you've written?

[Ludwig Nussel (l-n)]

AFAICS the only overlap in Roland's code is the function
get_subjectaltname_of_type() where one can retrieve a list of
subjaltnames of a given type. The function I proposed just returns a
list of all types. I can't judge what's the more useful API. Wrt
completeness his function lacks support for the ipaddess type which
is mandatory for certificate checks.

[Christopher (captain-c)]

With pyopenssl 0.10 and openssl 0.9.8.g on Ubuntu Karmic, I cannot retrieve extensions, and thus subjectAltName, from a certificate request object. When I output it the request object as text, it clearly shows a Requested Extensions section.

[Jean-Paul Calderone (exarkun)]

Merged the subjectAltName branch. This exposes extensions on certificates (not on certificate requests).