types: make Result an interface and move existing Result to separate package

types/current/types.go

@@ -0,0 +1,157 @@
+// Copyright 2016 CNI 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 current
+
+import (
+	"encoding/json"
+	"fmt"
+	"net"
+	"os"
+
+	"github.com/containernetworking/cni/pkg/types"
+)
+
+const implementedSpecVersion string = "0.2.0"
+
+var SupportedVersions = []string{"", "0.1.0", implementedSpecVersion}
+
+func NewResult(data []byte) (types.Result, error) {
+	result := &Result{}
+	if err := json.Unmarshal(data, result); err != nil {
+		return nil, err
+	}
+	return result, nil
+}
+
+func GetResult(r types.Result) (*Result, error) {
+	newResult, err := r.GetAsVersion(implementedSpecVersion)
+	if err != nil {
+		return nil, err
+	}
+	result, ok := newResult.(*Result)
+	if !ok {
+		return nil, fmt.Errorf("failed to convert result")
+	}
+	return result, nil
+}
+
+var resultConverters = []struct {
+	versions []string
+	convert  func(types.Result) (*Result, error)
+}{
+	{SupportedVersions, convertFrom020},
+}
+
+func convertFrom020(result types.Result) (*Result, error) {
+	newResult, ok := result.(*Result)
+	if !ok {
+		return nil, fmt.Errorf("failed to convert result")
+	}
+	return newResult, nil
+}
+
+func NewResultFromResult(result types.Result) (*Result, error) {
+	version := result.Version()
+	for _, converter := range resultConverters {
+		for _, supportedVersion := range converter.versions {
+			if version == supportedVersion {
+				return converter.convert(result)
+			}
+		}
+	}
+	return nil, fmt.Errorf("unsupported CNI result version %q", version)
+}
+
+// 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"`
+	DNS types.DNS `json:"dns,omitempty"`
+}
+
+func (r *Result) Version() string {
+	return implementedSpecVersion
+}
+
+func (r *Result) GetAsVersion(version string) (types.Result, error) {
+	for _, supportedVersion := range SupportedVersions {
+		if version == supportedVersion {
+			return r, nil
+		}
+	}
+	return nil, fmt.Errorf("cannot convert version %q to %s", SupportedVersions, version)
+}
+
+func (r *Result) Print() error {
+	data, err := json.MarshalIndent(r, "", "    ")
+	if err != nil {
+		return err
+	}
+	_, err = os.Stdout.Write(data)
+	return err
+}
+
+// String returns a formatted string in the form of "[IP4: $1,][ IP6: $2,] DNS: $3" where
+// $1 represents the receiver's IPv4, $2 represents the receiver's IPv6 and $3 the
+// receiver's DNS. If $1 or $2 are nil, they won't be present in the returned string.
+func (r *Result) String() string {
+	var str string
+	if r.IP4 != nil {
+		str = fmt.Sprintf("IP4:%+v, ", *r.IP4)
+	}
+	if r.IP6 != nil {
+		str += fmt.Sprintf("IP6:%+v, ", *r.IP6)
+	}
+	return fmt.Sprintf("%sDNS:%+v", str, r.DNS)
+}
+
+// IPConfig contains values necessary to configure an interface
+type IPConfig struct {
+	IP      net.IPNet
+	Gateway net.IP
+	Routes  []types.Route
+}
+
+// net.IPNet is not JSON (un)marshallable so this duality is needed
+// for our custom IPNet type
+
+// JSON (un)marshallable types
+type ipConfig struct {
+	IP      types.IPNet   `json:"ip"`
+	Gateway net.IP        `json:"gateway,omitempty"`
+	Routes  []types.Route `json:"routes,omitempty"`
+}
+
+func (c *IPConfig) MarshalJSON() ([]byte, error) {
+	ipc := ipConfig{
+		IP:      types.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
+}