From v1.70.0, an SFTP server started through the rc serve/start API with
a per-server proxyOpt.AuthProxy decided whether to enable proxy
authentication by checking the process-global proxy.Opt.AuthProxy
instead of the supplied proxyOpt.AuthProxy. In the normal rc case the
global is empty, so the auth proxy was silently ignored: the server
either failed to start with "no authorization found" or authenticated
against the local authorized_keys file instead of routing each login
through the proxy the operator configured.
The serve Provider refactor (f425f8d46) fixed the constructor by building the
provider from the supplied proxyOpt, but the authorized-keys handling in
configure() still consulted the global option. Make it depend on whether
proxy mode is actually active, and add a regression test for the
per-server option.
Nick Craig-Wood
65735be4da