internally, with code provided by sslgen.c. All SSL-layer-specific code is
then written in ssluse.c (for OpenSSL) and gtls.c (for GnuTLS).

As far as possible, internals should not need to know what SSL layer that is
in use. Building with GnuTLS currently makes two test cases fail.

TODO.gnutls contains a few known outstanding issues for the GnuTLS support.

GnuTLS support is enabled with configure --with-gnutls

layers and it won't make sense to provide a numerical version for it. I also
doubt that many people have used this for anything critical.

to explicitly disable that first with --without-ssl. Initial attempt.

include, as it seems at least some AIX versions don't really allow it to be
include at the same time as the original nameser.h.

X.

should come from <ws2tcpip.h>, but Winsock 1.1 should
suffice.

(IRIX 6.5.22 it seems)

code uses that

Provided implementations of inet_net_pton and inet_pton from BIND for systems that do not include these functions. These will be necessary for CIDR support and IPv6 support.

from url.c: Curl_disconnect().