ssh connection via a proxy

[Jeremy Fix <Jeremy.Fix@xxxxxxxxxxxxxxxxxx>]

Hello,

I would like to use libssh for connecting to a remote host via a
gateway, executing a command on the remote host and parsing its standard
outputs/errors; So the picture is  localhost -> gateway -> remote

I'm pretty new with libssh. I used to do that with command line ssh by
specifying 

    ssh -o ProxyCommand='ssh -W %h:%p mylogin@gateway' mylogin@remote
mycommand

It is not obvious to me how to do that with libssh; One track I have in
mind is a variant of the above with :

    ssh -L 9999:remote:22 mylogin@gateway

    ssh -p 9999 mylogin@localhost mycommand

therefore I would establish a tunnel then create a new libssh session on
localhost and execute the command in a channel on this new session.

I'm wondering if this is the right track to follow from implementing in
libssh this bounce over a proxy.

Thank you for your help.

Jeremy.