Re: [Caml-list] https and Ocamlnet

[Oliver Bandel <oliver@first.in-berlin.de>]

Quoting  Alan Schmitt <alan.schmitt@polytechnique.org> (snt: 2019-09-25 15:49 +0200 CEST) (rcv: 2019-09-25 15:49 +0200 CEST):
> Hello,
> 
> I have a small utility that downloads and parses the RSS feed from
> ocaml.org to include in the OCaml Weekly News, but a recent change to
> ocaml.org broke it: it seems to only be served through https. I tried to
> add a TLS provider, but it's still failing with a cryptic error message.
> 
> Here is an extract of the code showing the problem:
> 
> #+begin_src ocaml
> let () = Nettls_gnutls.init()
> 
> let site = "https://ocaml.org"
> let feed_name = "/feed.xml"
> 
> let planet = Nethttp_fs.http_fs site
> let feedic = planet # read [] feed_name
> let feed_string = Netchannels.string_of_in_obj_channel feedic
> let () = feedic # close_in()
> #+end_src
> 
> I can compile it with
> 
> ocamlfind ocamlc -o test -linkpkg -package netclient,nettls-gnutls test.ml
> 
> but when I run it, I get this error
> 
> Fatal error: exception Nettls_gnutls.TLS.Error(GNUTLS_E_PUSH_ERROR)
> 
> I know nothing of TLS and searching for the error did not point me
> toward any solution.
> 
> I'm using gnutls 3.6.9 and ocamlnet 4.1.6.
> 
> How can I access the site using https?
> 
> Thanks,
> 
> Alan

Someone else had explored the problem with gnutls and
GNUTLS_E_PREMATURE_TERMINATION:

Missing "Content-Length" header results in "The TLS connection was non-properly terminated"
  https://github.com/varnish/hitch/issues/127

Maybe that can help to find a solution here.

IMO it's good to have a library throwing an error / raising an exception
instead of ignoring it, but as user of that library it should be possible to catch it.

Don't know how to catch that exception with ocamlnet's Nettls_gnutls in
a convenient way.
If someone finds a solution to get the already read data even though the
exception was raised by gnutls/ocamlnet, please send it to the list.

Ciao,
  Oliver