Don't assert that all connections are wrapped, as they won't be if
the CloseConnOnCertChange setting is false. Only run the assertion
within a conditional for wrapped connections, where it is safe. This
prevents a panic from happening when CloseConnOnCertChange is not used.
Without this change, if a cert is updated (e.g. to add CNs) while the
listener is in the middle of Accept()ing a new connection, the
connection gets dropped, we'll see a message like this in the server
logs:
http: TLS handshake error from 127.0.0.1:51232: write tcp 127.0.7.1:8443->127.0.0.1:51232: use of closed network connection
and the client (like a browser) won't necessarily reconnect. This change
modifies the GetCertificate routine in the listener's tls.Config to
keep track of the state of the incoming connections and only close
connections that have completed GetCertificate and therefore are
finished with their TLS handshake, so that only old established
connections are closed.
Refreshing the cert should force renewal as opposed to returning
early if the SANs aren't changing. This is currently breaking refresh
of expired certs as per:
https://github.com/rancher/k3s/issues/1621#issuecomment-669464318
Signed-off-by: Brad Davidson <brad.davidson@rancher.com>
