Set the priority string to a concatenation of the connection cipher and curve strings, falling back to the context ones if the connection value isn't specified. Also get context.c to specify NULL for default context list and the opportunistic list for the connection, moving these library-specific quantities into the specific implementation.
Add a flag to the context (so, it's actually got something useful there!) and check the connection version on a successful handshake.
This means we need to access the context from a connection, so add a pointer to the context to the connection.
Link to the openssl val_secalgo implementation and use that, after adjusting the source of Nettle includes.
GnuTLS uses Nettle itself, so this is not adding a new dependency.
I could waste the rest of the available time trying to turn configure.ac into something that cleanly ignores OpenSSL, uses GnuTLS instead and retains all the options. Or even better scrap the whole autoconf mess and start again.
But in the interests of prototyping, do something quick and dirty. This means GnuTLS must for now be configured thus:
$ CFLAGS="-g" ../configure --enable-stub-only --with-gnutls --disable-gost --disable-ecdsa --disable-edns-cookies
to evade other items with hardcoded OpenSSL checks in them.
Convert the main util/val_secalgo.h to a plain interface. Move the preprocessor redefines into validator/val_secalgo.h, and move THAT under openssl, because it is OpenSSL implementation specific at present - you can compile with NSS and Nettle if config allows.
tls_min_version & tls_max_version settings must cause
failure when not supported by the TLS library. Not during
configure time, but during connection setup so it doesn't
hamper alternative transports.
* Fix for DNSSEC bug in finding most specific key when
trust anchor proves non-existance of one of the labels
along the authentication chain other than the non-
existance of a DS record on a zonecut.