A new KerberosFactory was constructed for every dial, so the client,
error and ccache modification time caches it holds were discarded
after a single use. Every new SMB connection re-read the Kerberos
config, re-parsed the ccache and did a fresh KDC exchange.
Share a single factory so clients are cached across connections as
intended, and refreshed when the ccache file changes.
This change enhances the SMB backend in Rclone to automatically refresh
Kerberos credentials when the associated ccache file is updated.
Previously, credentials were only loaded once per path and cached
indefinitely, which caused issues when service tickets expired or the
cache was renewed on the server.
Nick Craig-Wood
Sudipto Baral
Jonathan Giannuzzi