GnuTLS identity verification improvements
We support GNetworkAddress, GNetworkService, and GInetSocketAddress. If we receive some other type of GSocketConnectable, we should fail with an error rather than fail to verify the identity.
I doubt this check will be hit in practice, but better safe than sorry.
Also:
Currently GTlsDatabase and GTlsConnection both rely on GnuTLS to verify the peer identity, but GTlsCertificate does it manually. There's no good reason for this.