It should not be possible to have a DHCP lease on a link without also having
an associated network. Add assert() to avoid compiler warnings.
Reported by Thomas H. P. Andersen
When enabled in [Network] it will set up a dhcp server on the interface, listening
on one of its statically configured IPv4 addresses and with a fixed size pool of
leases determined from it.
Example:
[Match]
Name=ve-arch-tree
[Network]
Address=192.168.12.5/24
DHCPServer=yes
[Route]
Gateway=192.168.12.5
Destination=192.168.12.0/24
In this case we will configure ve-arch-tree with the address 192.168.12.5 and
hand out addresses in the range 192.168.12.6 - 192.168.12.38.
In the future, we should (as suggested by Lennart) introduce a syntax to pick the
server address automatically.
Configuration will be in
root:root /run/systemd/network
and state will be in
systemd-network:systemd-network /run/systemd/netif
This matches what we do for logind's seat/session state.
This makes callback behaviour more like sd-event or sd-resolve, and
creates proper object for unregistering callbacks.
Taking the refernce to the slot is optional. If not taken life time of
the slot will be bound to the underlying bus object (or in the case of
an async call until the reply has been recieved).
Make the logging less verbose by only printing all the changed flags on one line,
at the same time make it more complete by supporting all flags currently supported
by the kernel.
We still fall back to printing the raw flags in case we get something we do not recognize
This may be useful when running on new kernels.
We need to take a refcount on the link whenever we expect a callback. The exceptions
are the ipv4ll/dhcp clients as their lifetimes are guaranteed to be shorter than that
of the link.
Otherwise:
eth0: unknown link flags gained: 0x00040 (ignoring)
[tomegun: hiding these messages is ok, as IFF_RUNNING is redundant
and can be deduced from operstate and IFF_LOWER_UP]
To make sure we don't delay boot on systems where (some) network links are managed by someone else
we don't block if something else has successfully brought up a link.
We will still block until all links we are aware of that are managed by networkd have been
configured, but if no such links exist, and someone else have configured a link sufficiently
that it has a carrier, it may be that the link is ready so we should no longer block.
Note that in all likelyhood the link is not ready (no addresses/routes configured),
so whatever network managment daemon configured it should provide a similar wait-online
service to block network-online.target until it is ready.
The aim is to block as long as we know networking is not fully configured, but no longer. This
will allow systemd-networkd-wait-online.service to be enabled on any system, even if we don't
know whether networkd is the main/only network manager.
Even in the case networking is fully configured by networkd, the default behavior may not be
sufficient: if two links need to be configured, but the first is fully configured before the
second one appears we will assume the network is up. To work around that, we allow specifying
specific devices to wait for before considering the network up.
This unit is enabled by default, just like systemd-networkd, but will only be pulled in if
anyone pulls in network-online.target.
This properly detects the state of the link based on both the link flags and the
operstate.
Moreover, always log state-changes even if we are not yet managing the link.
Avoid having two code-paths racing with eacother to do the same thing. The change
of flags will be detected in the normal way, so only use the link_up_handler
to detect if the 'up' failed and in that case fail the link.
