Qubes Salt state module for downloading files to offline VMs

[rootkovska]

It would be useful in some scenarios to be able to state something like this (imagine this being part of e.g. my-offline-vm.sls state file):

get some tgz from the untrusted Web:
  qubes.get_file_via_dispvm:
    - source: http://somewhere.com/somefile.tgz
    - sha1: adc83b19e793491b1c6ea0fd8b46cd9f32e592fc

Salt would then spawn a DispVM (connected to the net, so this would not be a DispVM started from the VM in question, as in that case it would inherit network-not-having property), and then wget the requested files. Subsequently the file would be checked against the hash given, and if matches, copied to the target offline AppVM using qubes.Filecopy service.

This way we would be able to prepare custom offline AppVMs which require e.g. custom sources from the Web, such as e.g. an AppVM for running Electrum + Trezor.