Cancel fail-closed sessions before sending recording upload failure
notifications. Bound each notifyControl request to five seconds, including
recorder connection failures on the synchronous session startup path.
An unresponsive control request must not keep an unrecorded session running
or indefinitely delay rejection or fail-open startup.
Keep the timeout local to each notification, independent of the session
and upload lifetime, without adding another goroutine. Test blocked
startup notifications in both rejection and fail-open modes, and use
virtual time to cover earlier and simultaneous cancellation/deadlines.
Send SFTP recording rejection diagnostics to stderr, preserving the binary protocol on stdout and exit status 254. Add real SSH/recorder tests for fail-closed and fail-open behavior with blocked notifications, and an SFTP client regression test.
Updates tailscale/corp#50380
Signed-off-by: James Tucker <james@tailscale.com>
Change-Id: I270d624975a6a9115502a4915ee5ff28a67d714b
James Tucker
84ca98e518