C → S {type: 'Iauth', name: …, auth_type: …}
Iauth – authentication answer to "unauthorised" challenge.
Arguments:
C → S {type: 'Iauth', name: …, auth_type:'digest', auth: …, response: …}
C → S {type: 'Iauth', name: …, auth_type:'rtoken', token: …}
unauthorised