If the user has already mapped the hostname to some other address,
assume the user knows what they are doing (since they probably do)
and leave that mapping alone, and create a minimal 127.0.0.1 entry.
If there was no hostname mapping, add it to the 127.0.0.1 entry
like NM did before.
Having the original hostname checks in the settings-service code
didn't allow the policy enough granularity to differentiate between
a plugin-provided hostname and the original hostname. We want to
fall back to the original hostname if there isn't a persistent
hostname (from a plugin) and if there isn't a DHCP-provided
hostname. Moving the original hostname checks to the policy
makes that possible. Clarify the precedence order at the same
time, and minimally validate the DHCP hostname as well.
Sometimes cause the cache not to refill with all interfaces,
meaning NM sometimes got the wrong carrier state from the
kernel which prevented NM from taking over existing connections.
nm_device_set_use_dhcp() and nm_device_get_use_dhcp() were somewhat
confusing and don't really reflect the new DHCP architecture with
NMDHCPClient. Now that timeout and state signals are specific to
the NMDHCPClient it doesn't make sense to check for DHCP use
in the callbacks for those signals since they'll never get called
if DHCP isn't in use. We might as well just keep the DHCP manager
around and check whether a DHCP client instance exists when we need
to figure out whether DHCP is in use.
Since the same interface could be used for both DHCPv4 and DHCPv6 we
can't just use 'iface' for tracking DHCP client lease changes. Instead
use a generated client ID, and track DHCP events based on the client's
PID instead of interface name.
NM shouldn't really be calling Enable(False) except in response to
direct user requests to turn off WWAN, much like rfkill, since
Enable(False) /is/ essentially rfkill for 3G. Instead, we should
be powering up the modem before trying to use it, and only
disconnecting after we're done. Let the user do enable/disable
when they want to.
This also fixes issues with other devices like GPS potentially
using the modem-manager at the same time as NM and ensures that NM
won't punch the modem in the face while GPS is using it.
