tls-crypt-v2: add script hook to verify metadata

tls-crypt-v2: add script hook to verify metadata

To allow rejecting incoming connections very early in the handshake,
add a --tls-crypt-v2-verify option that allows administators to
run an external command to verify the metadata from the client key.
See doc/tls-crypt-v2.txt for more details.

Because of the extra dependencies, this requires adding a mock
parse_line() to the tls-crypt unit tests.  Also, this turns tls_wrap_free
into a static inline function, so that we don't need to compile in ssl.c
(and all of it's dependencies) with the unit tests.

Signed-off-by: Antonio Quartulli <antonio@openvpn.net>
Signed-off-by: Steffan Karger <steffan.karger@fox-it.com>
Acked-by: Antonio Quartulli <antonio@openvpn.net>
Message-Id: <1540208715-14044-6-git-send-email-steffan.karger@fox-it.com>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg17789.html
Signed-off-by: David Sommerseth <davids@openvpn.net>