GUE and FOU encapsulation in tunnels

[opirko]

Hello, I'd like to utilize encapsulation in certain tunnels, for example GUE in an IPIP tunnel. I was looking briefly through libnl code and didn't find a straightforward way to set this. I'd hope it would be in ipip.h. Did I miss the part of the code where it can be achieved? If it can't, is it possible to add this feature to libnl? Is it a difficult addition?