Corrects the pattern of using errgroup's and context cancellation to simplify the logic for canceling extra routines for the QUIC connection. This is because the extra context cancellation is redundant with the fact that the errgroup also cancels it's own provided context when a routine returns (error or not).
For the datagram handler specifically, since it can respond faster to a context cancellation from the QUIC connection, we wrap the error before surfacing it outside of the QUIC connection scope to the supervisor. Additionally, the supervisor will look for this error type to check if it should retry the QUIC connection. These two operations are required because the supervisor does not look for a context canceled error when deciding to retry a connection. If a context canceled from the datagram handler were to be returned up to the supervisor on the initial connection, the cloudflared application would exit. We want to ensure that cloudflared maintains connection attempts even if any of the services on-top of a QUIC connection fail (datagram handler in this case).
Additional logging is also introduced along these paths to help with understanding the error conditions from the specific handlers on-top of a QUIC connection.
Related CUSTESC-53681
Closes TUN-9610
Some more legacy h2mux code to be cleaned up and moved out of the way.
The h2mux.Header used in the serialization for http2 proxied headers is moved to connection module. Additionally, the booleanfuse structure is also moved to supervisor as it is also needed. Both of these structures could be evaluated later for removal/updates, however, the intent of the proposed changes here is to remove the dependencies on the h2mux code and removal.
Approved-by: Chung-Ting Huang <chungting@cloudflare.com>
Approved-by: Luis Neto <lneto@cloudflare.com>
Approved-by: Gonçalo Garcia <ggarcia@cloudflare.com>
MR: https://gitlab.cfdata.org/cloudflare/tun/cloudflared/-/merge_requests/1576
Devin Carr
Nuno Diegues
Igor Postelnik
Areg Harutyunyan
cthuang