Nodes without private IPs

Allow nodes to have no private IPs.
Nodes without private IPs will automatically be put into
their own location.

pkg/encapsulation/noop.go

@@ -0,0 +1,59 @@
+// Copyright 2021 the Kilo authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package encapsulation
+
+import (
+	"net"
+
+	"github.com/squat/kilo/pkg/iptables"
+)
+
+// Noop is an encapsulation that does nothing.
+type Noop Strategy
+
+// CleanUp will also do nothing.
+func (n Noop) CleanUp() error {
+	return nil
+}
+
+// Gw will also do nothing.
+func (n Noop) Gw(_ net.IP, _ net.IP, _ *net.IPNet) net.IP {
+	return nil
+}
+
+// Index will also do nothing.
+func (n Noop) Index() int {
+	return 0
+}
+
+// Init will also do nothing.
+func (n Noop) Init(_ int) error {
+	return nil
+}
+
+// Rules will also do nothing.
+func (n Noop) Rules(_ []*net.IPNet) []iptables.Rule {
+	return nil
+}
+
+// Set will also do nothing.
+func (n Noop) Set(_ *net.IPNet) error {
+	return nil
+}
+
+// Strategy will finally do nothing.
+func (n Noop) Strategy() Strategy {
+	return Strategy(n)
+}