Add plugin code

This adds basic plugins.
"main" types: veth, bridge, macvlan
"ipam" type: host-local

The code has been ported over from github.com/coreos/rkt project
and adapted to fit the CNI spec.

plugin/types.go

@@ -0,0 +1,106 @@
+// Copyright 2015 CoreOS, Inc.
+//
+// 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 plugin
+
+import (
+	"encoding/json"
+	"net"
+
+	"github.com/appc/cni/pkg/ip"
+)
+
+// NetConf describes a network.
+type NetConf struct {
+	Name string `json:"name,omitempty"`
+	Type string `json:"type,omitempty"`
+	IPAM struct {
+		Type string `json:"type,omitempty"`
+	} `json:"ipam,omitempty"`
+}
+
+// Result is what gets returned from the plugin (via stdout) to the caller
+type Result struct {
+	IP4 *IPConfig `json:"ip4,omitempty"`
+	IP6 *IPConfig `json:"ip6,omitempty"`
+}
+
+// IPConfig contains values necessary to configure an interface
+type IPConfig struct {
+	IP      net.IPNet
+	Gateway net.IP
+	Routes  []Route
+}
+
+type Route struct {
+	Dst net.IPNet
+	GW  net.IP
+}
+
+// net.IPNet is not JSON (un)marshallable so this duality is needed
+// for our custom ip.IPNet type
+
+// JSON (un)marshallable types
+type ipConfig struct {
+	IP      ip.IPNet `json:"ip"`
+	Gateway net.IP   `json:"gateway,omitempty"`
+	Routes  []Route  `json:"routes,omitempty"`
+}
+
+type route struct {
+	Dst ip.IPNet `json:"dst"`
+	GW  net.IP   `json:"gw,omitempty"`
+}
+
+func (c *IPConfig) MarshalJSON() ([]byte, error) {
+	ipc := ipConfig{
+		IP:      ip.IPNet(c.IP),
+		Gateway: c.Gateway,
+		Routes:  c.Routes,
+	}
+
+	return json.Marshal(ipc)
+}
+
+func (c *IPConfig) UnmarshalJSON(data []byte) error {
+	ipc := ipConfig{}
+	if err := json.Unmarshal(data, &ipc); err != nil {
+		return err
+	}
+
+	c.IP = net.IPNet(ipc.IP)
+	c.Gateway = ipc.Gateway
+	c.Routes = ipc.Routes
+	return nil
+}
+
+func (r *Route) UnmarshalJSON(data []byte) error {
+	rt := route{}
+	if err := json.Unmarshal(data, &rt); err != nil {
+		return err
+	}
+
+	r.Dst = net.IPNet(rt.Dst)
+	r.GW = rt.GW
+	return nil
+}
+
+func (r *Route) MarshalJSON() ([]byte, error) {
+	rt := route{
+		Dst: ip.IPNet(r.Dst),
+		GW:  r.GW,
+	}
+
+	return json.Marshal(rt)
+}