Currently the local variable `address` is unintialized if the DHCP lease
doesn't provide a router address (when r == -ENODATA). Thus the
subsequent call to route_scope_from_address will result in accessing an
unintialized variable.
As a matter of fact, sd-dhcp-client ignores DHCP leases without an
address so link_dhcp_set_routes probably will never be called without a
valid address.
DHCP responses could include static routes, but unfortunately not an
option to tell what scope to use. So it's important that the client sets
it properly.
This mimics what the `ip route add` command does when adding a static
route without an explicit scope:
* If the destination IP is on the local host, use scope `host`
* Otherwise if the gateway IP is null (direct route), use scope `link`
* If anything else, use the current default `global`.
Fixes#5979.
This adds a modified version of dhcp6_option_parse_domainname() that is
able to parse compressed domain names, borrowing the idea from
dns_packet_read_name(). It also adds pieces in networkd-link and
networkd-manager to properly save/load the added option field.
Resolves#2710.
Daniel Wang