This backports the code responsible for SPKI digests from release/4.
It also adjusts doc/reference.conf to note that SPKI digests are now
supported, and how to generate them. It does NOT backport the mkfingerprint
program -- the instructions in reference.conf are sufficient. I am ofcourse
open to anyone else backporting the program, but I don't see the need.
Nothing in the Charybdis or libratbox code calls rb_get_pseudo_random
and under OpenSSL it uses RAND_pseudo_bytes() which is both dangerous
and removed in OpenSSL version 1.1.0.
This lets a user connect with a client certificate, and
passes the certificate's fingerprint to ircd, which
currently just notices it to the user.
A new ssld->ircd message 'F' is used to pass on the
fingerprint.
This is only for OpenSSL for now, not GNUTLS.
