Legacy PerRPCCredentials with RequireTransportSecurity don't consider TransportCredentials SecurityLevel

[dfawley]

No description provided.

[dfawley]

From #3964 (comment):

Yes, that all sounds right to me. But note that the check in clientconn.go can't be improved since the TransportCredentials don't report their security level until after the connection is established. So the only place we can do this is in http2_client.go, and it will have to be a connection failure and not a channel-creation failure.

Actually -- would this be a per-call failure? I believe we can check at connection time or call time (or both).

[yihuazhang]

You are right. We should do checks at both connection and call times as it is always preferred to reject early if possible. For per-connection check, I believe you should add a similar check in DialContext() API in clientconn.go.

[yihuazhang]

Sorry, I missed your previous comment on "not being able to improve the check in clientconn.go", and I agree with it. And if PerRPCCredentials.RequireTransportSecurity()==true, I believe we should require ==PrivacyAndIntegrity.

[easwars]

Can this be closed now?