bug#31946: 27.0.50; The NSM should warn about more TLS problems

[Eli Zaretskii]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Cc: 31946@debbugs.gnu.org,  Noam Postavsky <npostavs@gmail.com>, Eli 
> Zaretskii <eliz@gnu.org>
> Date: Wed, 27 Jun 2018 14:20:16 +0200
> 
> Speaking of which -- it's quite a mouthful to say:
> 
> (open-network-stream
>  "foo" nil "dh-composite.badssl.com" "https"
>  :tls-parameters (cons 'gnutls-x509pki (gnutls-boot-parameters
>                                         :hostname "dh-composite.badssl.com")))
> 
> I've been meaning to add a :tls keyword to `open-network-stream' that
> would make
> 
> (open-network-stream "foo" nil "dh-composite.badssl.com" "https" :tls t)
> 
> a short way to write the above.  I.e., the default TLS parameters (which
> is what you need in 99.9% of the cases) would be used if you just say
> :tls t.
> 
> Does that sound OK to you, Eli?

Sounds good, but does it really require a new property?  Why not a
special value of the existing :tls-parameters?  For example:

  (open-network-stream "foo" nil "dh-composite.badssl.com" "https"
                       :tls-parameters 'tls-defaults)