Re: [PATCH v6] http: add http.sslVerifyStatus to check stapled OCSP responses

> From: Grayson Gordon <graysongordon1@gmail.com>
>
> git never sets CURLOPT_SSL_VERIFYSTATUS, so libcurl never requests the
> OCSP "Certificate Status Request" extension and any stapled response a
> server sends is ignored, including responses that explicitly state the
> certificate has been revoked.
>
> Add an http.sslVerifyStatus boolean that maps to
> CURLOPT_SSL_VERIFYSTATUS.
> http_options() is already the collect_fn for a urlmatch config, so the
> per-URL form works with no changes:
>
>     git config http.https://example.com/.sslVerifyStatus true
>
> Defaults to false/"off". This is due to the nature of the OCSP protocol.
> If enabled, git would expect to receive OCSP stapled responses. If the
> stapled responses were not present, the connection would be blocked as
> the status of the server's certificate could not be verified. This would
> break connections to legitimate services that don't use OCSP as their
> certificate revocation mechanism.
>
> If the backend can't check the staple, curl_easy_setopt() returns
> CURLE_NOT_BUILT_IN. Error message includes curl_easy_strerror() with
> the option name to enable users to more easily identify a libcurl
> built without status verification.
>
> CURLOPT_SSL_VERIFYSTATUS has existed since libcurl 7.41.0, below our
> 7.61.0 floor, so no version guard is needed.
>
> Tests are in t5551.
>
> Additional note - I put this in http.adoc:
> "Defaults to false, which
> allows connections to remotes without validating whether or not
> the certificate has been revoked by the certificate authority."
>
> Technically, there are cases with older combinations of GnuTLS
> and curl where the revocation logic actually WILL NOT allow
> such connections. Search "OCSP" in the lore for full details.
>
> Signed-off-by: Grayson Gordon <graysongordon1@gmail.com>
> ---
>  Documentation/config/http.adoc | 14 ++++++++++++++
>  http.c                         | 14 ++++++++++++++
>  t/t5551-http-fetch-smart.sh    | 29 +++++++++++++++++++++++++++++
>  3 files changed, 57 insertions(+)