QUIC will need ssl_client_cert_callback implementation after PR #6699 has landed

[shinrich]

I do not see where to put the analogous callback in the QUIC code, so filing this issue for others to remember and add it in.

[maskit]

The callback function, ssl_client_cert_callback should be set in quic_init_client_ssl_ctx().

I don't have strong opinion on where to put the callback function but I'd follow the same way as other XSupport classes and move most code currently in the callback function to the XSupport class for this.

[github-actions]

This issue has been automatically marked as stale because it has not had recent activity. Marking it stale to flag it for further consideration by the community.

[bryancall]

This TODO was tied to the original in-house QUIC implementation. That stack was removed in 2023 (#10703) and replaced with a quiche-based stack that manages TLS differently (via quiche_config_*), so the specific quic_init_client_ssl_ctx() hook this issue described no longer applies. Closing as moot. If outbound QUIC client-certificate support is something you need on the current stack, please open a new issue describing the use case so it can be scoped against the new code.

Update: the original QUIC stack was removed as of the 10.0.0 release, so this is moot from 10.0.0 onward (current: 10.1.2).