mxrouterctl: Factor out common code

Factor out common code of `mxrouterctl start` and `mxrouterctl restart`.

mxrouter/mxrouterctl

@@ -770,6 +770,23 @@ sub start_process_if {
 
 ##########################################
 
+sub prepare_netns_interfaces {
+		# 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);
+		}
+}
+
+##########################################
+
 my @SAVED_ARGV=@ARGV;
 
 GetOptions(OPTIONS) or die USAGE;
@@ -808,36 +825,15 @@ if (!$opt_this_ns) {
 
 		have_netns($NETNS) and die "already running (network namespace $NETNS already exists)\n";
 		create_netns($NETNS);
-		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', $NETNS);
-		}
+		prepare_netns_interfaces();
 		system('ip','netns','exec',$NETNS,$0,'--this-ns',@SAVED_ARGV) and exit 1;
 	} elsif ($cmd eq 'stop') {
 		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);
-		}
+		prepare_netns_interfaces();
 		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";