The network case is more complex. There are several potential
changes in the network configuration that other modules may need
to know about. EBox::NetworkObserver has
four methods that the network module invokes when different
types of changes are made, and two methods that tell modules
to remove references to certain network interfaces from their
configurations:
staticIfaceAddressChangedInvoked when the address of an static network interface
is going to be changed, this method receives the old
and new addresses and masks as arguments. Returning a
true value means that this module's
configuration would become inconsistent if such a change was
made. In that case the network module will not make the change,
but warn the user instead.
ifaceMethodChangedInvoked when the configuration method for a network
interface is going to change. Both the old and new methods
are passed as arguments to this function. They are strings:
static, dhcp,
trunk or notset.
As with the previous function, a return value of
true will prevent the change from being
made.
vifaceAddedInvoked when a new virtual interface is going to be
created. Its arguments are the real interface to which
it's going to be added, the name of the new interface,
its ip address and its netmask. It works the same way: it
returns true if the creation of the
virtual interface is incompatible with your module's current
configuration.
vifaceDeleteInvoked when a virtual interface is going to be removed. Its arguments are the names of the real and virtual interfaces. It works exactly the same way as the three methods above.
freeIfaceIt tells your module to remove all reference to a network
interface from its configuration. It is usually called after
you returned true in one of the methods
above and the user insisted on doing whatever change he was
trying to do.
freeVifaceThe same as freeIface, but for
virtual interfaces.
Example 4.2 shows the implementation
of EBox::NetworkObserver methods in the
firewall module.
Example 4.2. Implementing a
EBox::NetworkObserver
sub ifaceMethodChanged # (iface, oldmethod, newmethod)
{
my ($self, $iface, $oldm, $newm) = @_;
($newm eq 'static') and return undef;
($newm eq 'dhcp') and return undef;
return $self->usesIface($iface);
}
sub vifaceDelete # (iface, viface)
{
my ($self, $iface, $viface) = @_;
return $self->usesIface("$iface:$viface");
}
sub usesIface # (iface)
{
my ($self, $iface) = @_;
my @reds = $self->all_dirs("redirections");
foreach (@reds) {
if ($self->get_string("$_/iface") eq $iface) {
return 1;
}
}
return undef;
}
sub freeIface # (iface)
{
my ($self, $iface) = @_;
$self->removePortRedirectionOnIface($iface);
}
sub freeViface # (iface, viface)
{
my ($self, $iface, $viface) = @_;
$self->removePortRedirectionOnIface("$iface:$viface");
}