On the client side, are you passing a ca_certs file with the self-signed
certificate in it?  If not, the library won't be able to validate the
certificate enough to be able to see the data in it.  But if you do
that, you should be able to see the bits of the certificate.  There's no
point to seeing the bits of an unvalidated certificate, because they may
be forged.  So the library doesn't allow you to see the bits of an
unvalidated certificate from the other side of the connection.