invoke openconnect with originally-input server hostname rather than IP, to ensure that 'Host: ' header matches originally-input hostname
Previously, NM-oc invoked
openconnect --servercert $HASH $IP:$PORT for the connection phase. This causes problems for VPN servers implemented as name-based vhosts, where a
Host: [IPv4_address] header in the HTTPS request(s) will lead to errors. See #46 (closed) for an example.
With this change, NM-oc invokes
openconnect --servercert $HASH --resolve $HOSTNAME:$IP $HOSTNAME:$PORT, which ensures that the
Host: header contains a real hostname wherever possible and leaves certificate handling unchanged.