CDRIVER-4206 KMIP support

[kevinAlbs]

Summary

Implements the specification changes of DRIVERS-1353. Please see the comments of DRIVERS-1353 for the linked specification change commits.

• Add mongoc_auto_encryption_opts_set_tls_opts and mongoc_client_encryption_opts_set_tls_opts to set custom TLS options on KMS connections.
• Update specification tests and prose tests.
• Update CSFLE documentation:
  • Add KMIP KMS provider.
  • Add missing documentation for Azure and GCP KMS providers (CDRIVER-4087).
  • Fix documentation for local KMS provider (CDRIVER-4088).

Rejected alternatives

Passing TLS options with mongoc_ssl_opt_t

The specification is not prescriptive in the API for passing TLS options:

Drivers SHOULD provide API that is consistent with configuring TLS options for MongoDB server TLS connections. New API to support the options MUST be independent of the KMS provider to permit future extension. The following is an example:

I considered an alternative API for passing TLS options:

void
mongoc_auto_encryption_opts_set_tls_opts (
   mongoc_auto_encryption_opts_t *opts,
   const char* provider,
   const mongoc_ssl_opt_t *ssl_opt
);

It is more consistent with mongoc_client_set_ssl_opts. But I chose to reject it because:

• The mongoc_ssl_opt_t does not permit configuring all TLS options supported in the URI specification (tlsDisableOCSPEndpointCheck, tlsDisableCertificateRevocationCheck).
• mongoc_ssl_opt_t includes insecure options (allow_invalid_hostname and weak_cert_validation) which are prohibited in the specification, as well as C specific options ca_dir and crl_file, which are not required and are not supported on all TLS implementations.
• SSL is a deprecated term in favor of TLS. E.g. mongoc_uri_get_ssl is deprecated for mongoc_uri_get_tls.

Caveats

• Error messages in the "no client certificate" cases are empty. Commented inline.

[chardan]

Lots of work in here! I especially appreciate the careful documentation. Please take a look at just a few things in here.

[eramongodb]

Other than some minor formatting, LGTM. 👍

[chardan]

Strong improvements! Just a couple of things you may want to consider, but +1 from me.