mxrouterctl: Handle interface changes on reload

Changes of interface() and veth() calls in the config are currently not
handled by 'mxrouterctl restart'

Add code to handle interface changes on 'mxrouterctl restart'.

Following config requests, physical interfaces are moved between the
network namespaces of pid 1 and that of the router and veth interface
pairs are created in both namespaces or deleted.

mxrouter/mxrouterctl

@@ -373,9 +373,30 @@ sub radvd {
 	$radvd{$if}=$conf;
 }
 
-our $want_if;
+# 'lo' implied without config. Note: ipv6 seems to *need* lo for unknown reasons
+our $want_if = {'lo' => 1};    # includes lo, veth and physical devices but not vlan devices
 our $want_veth;
 
+sub configure_if {
+	my ($want_if)=@_;
+	for my $if (keys %$want_if) {
+		netif_is_up($if) or  sys('ip', 'link', 'set', $if, "up");
+	}
+}
+
+sub unconfigure_if {
+	my ($have_if)=@_;
+	for my $if (keys %$have_if) {
+		if (-d "/sys/class/net/$if/device") {
+			# hardware device
+			sys('ip', 'link', 'set', $if, 'netns', 1);
+		} else {
+			# virtual device
+			sys('ip', 'link', 'del', $if);
+		}
+	}
+}
+
 our $DHCRELAY_FORWARD;
 our %DHCRELAY_IF;
 
@@ -411,7 +432,6 @@ sub disable_ipv4_rp_filter {
 
 
 
-
 sub start {
 
 	-d "/var/run/mxrouter/$NETNS" or sys ('mkdir','-p',"/var/run/mxrouter/$NETNS");
@@ -480,12 +500,16 @@ sub start {
 	my $have_addr=read_active_ip();
 	my ($new_addr,$del_addr)=({},{});
 
-	# for some yet unknown reason, ipv6 seems to need loopback....
-
-	netif_is_up('lo') or sys('ip link set lo up');
-
-	for my $dev (keys %$want_if, keys %$want_veth) {
-		netif_is_up($dev) or sys('ip','link','set',$dev,'up');
+	my $have_if = {map {$_ => 1} network_devices()};
+	for (keys %$want_if) {
+		exists $have_if->{$_} or warn "Interface $_ not available\n";
+	}
+	my $del_if={};
+	for (keys %$have_if) {
+		exists $want_if->{$_}
+			|| exists $want_vlan->{$_}
+			|| $_ eq 'lo'
+			or $del_if->{$_} = 1;
 	}
 
 	my ($have_vlan)=read_active_vlans();
@@ -554,7 +578,9 @@ sub start {
 	unconfigure_route($del_route);
 	unconfigure_ip($del_addr);
 	unconfigure_vlans($del_vlan,{});
+	unconfigure_if($del_if);
 
+	configure_if($want_if);
 	configure_vlans($new_vlan,{});
 	configure_ip($new_addr);
 	configure_route($new_route);
@@ -625,6 +651,7 @@ sub interface {
 
 sub veth {
 	my ($dev) = @_;
+	$want_if->{$dev} = 1;
 	$want_veth->{$dev} = 1;
 }
 
@@ -793,6 +820,21 @@ if (!$opt_this_ns) {
 		have_netns($NETNS) or die "not running (network namespace $NETNS does not exist)\n";
 		system('ip','netns','exec',$NETNS,$0,'--this-ns',@SAVED_ARGV) and exit 1;
 		delete_netns($NETNS);
+	} elsif ($cmd eq 'reload') {
+		have_netns($NETNS) or die "not running (network namespace $NETNS does not exist)\n";
+		# create veth pair if not yet available
+		for my $dev (sort keys %$want_veth) {
+			-d "/sys/class/net/$dev" and next;
+			sys('ip', 'link', 'add', $dev, 'type', 'veth', 'peer', 'name', $dev, 'netns', $NETNS);
+			sys('ip', 'link', 'set', $dev, 'up');
+		}
+		# move interfaces which are still in the init namespace
+		# ignore veth devices and lo, which exists in both namespaces
+		for my $dev (sort keys %$want_if) {
+			$dev eq 'lo'  || $want_veth->{$dev} and next;
+			-d "/sys/class/net/$dev" and sys('ip', 'link', 'set', $dev, 'netns', $NETNS);
+		}
+		system('ip', 'netns', 'exec', $NETNS,$0,'--this-ns', @SAVED_ARGV) and exit 1;
 	} else {
 		have_netns($NETNS) or die "not running (network namespace $NETNS does not exist)\n";
 		system('ip','netns','exec',$NETNS,$0,'--this-ns',@SAVED_ARGV) and exit 1;