Instead of using the first address we find on an interface we should
consider properties like an address' scope or whether it is temporary
or public.
Fixes#543.
Even in Main Mode, some Sonicwall boxes seem to send ID/HASH payloads in
unencrypted form, probably to allow PSK lookup based on the ID payloads. We
by default reject that, but accept it if the
charon.accept_unencrypted_mainmode_messages option is set in strongswan.conf.
Initial patch courtesy of Paul Stewart.
Tobias Brunner