[libvirt] [RFC] Overriding graphics relocation URI

Hi all. Graphics relocation URI is currently transmitted within migration cookie in the form of graphics type, address, port, tlsPort, and certificate subject. The cookie is generated by target libvirtd and consumed by source libvirtd which than forwards this data through QEMU to the graphics client. In case the target libvirtd is not able to provide the data in a way usable by the client (e.g., because it needs to use different address), we need to provide a way to override the graphics URI. We already support similar thing for migration URI. So the question is how we can support $SUBJ? The only way I came up with is to introduce another set of migration APIs (such as virDomainMigrateToURI3, ...) with an additional graphics URI parameter. The URI would be formed as type "://" address ":" port "?tlsPort=" tlsPort "&subject=" cert with various parts being optional. That would allow us to override any part of the graphics cookie we need. However, I don't like the addition of another set of migration APIs and I'd be glad to hear better ideas :-) Jirka