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// Copyright 2015 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 invoke
import (
"context"
"encoding/json"
"fmt"
"os"
"github.com/containernetworking/cni/pkg/types"
"github.com/containernetworking/cni/pkg/types/create"
"github.com/containernetworking/cni/pkg/version"
)
// Exec is an interface encapsulates all operations that deal with finding
// and executing a CNI plugin. Tests may provide a fake implementation
// to avoid writing fake plugins to temporary directories during the test.
type Exec interface {
ExecPlugin(ctx context.Context, pluginPath string, stdinData []byte, environ []string) ([]byte, error)
FindInPath(plugin string, paths []string) (string, error)
Decode(jsonBytes []byte) (version.PluginInfo, error)
}
// Plugin must return result in same version as specified in netconf; but
// for backwards compatibility reasons if the result version is empty use
// config version (rather than technically correct 0.1.0).
// https://github.com/containernetworking/cni/issues/895
func fixupResultVersion(netconf, result []byte) (string, []byte, error) {
versionDecoder := &version.ConfigDecoder{}
confVersion, err := versionDecoder.Decode(netconf)
if err != nil {
return "", nil, err
}
var rawResult map[string]interface{}
if err := json.Unmarshal(result, &rawResult); err != nil {
return "", nil, fmt.Errorf("failed to unmarshal raw result: %w", err)
}
// Manually decode Result version; we need to know whether its cniVersion
// is empty, while built-in decoders (correctly) substitute 0.1.0 for an
// empty version per the CNI spec.
if resultVerRaw, ok := rawResult["cniVersion"]; ok {
resultVer, ok := resultVerRaw.(string)
if ok && resultVer != "" {
return resultVer, result, nil
}
}
// If the cniVersion is not present or empty, assume the result is
// the same CNI spec version as the config
rawResult["cniVersion"] = confVersion
newBytes, err := json.Marshal(rawResult)
if err != nil {
return "", nil, fmt.Errorf("failed to remarshal fixed result: %w", err)
}
return confVersion, newBytes, nil
}
// For example, a testcase could pass an instance of the following fakeExec
// object to ExecPluginWithResult() to verify the incoming stdin and environment
// and provide a tailored response:
//
//import (
// "encoding/json"
// "path"
// "strings"
//)
//
//type fakeExec struct {
// version.PluginDecoder
//}
//
//func (f *fakeExec) ExecPlugin(pluginPath string, stdinData []byte, environ []string) ([]byte, error) {
// net := &types.NetConf{}
// err := json.Unmarshal(stdinData, net)
// if err != nil {
// return nil, fmt.Errorf("failed to unmarshal configuration: %v", err)
// }
// pluginName := path.Base(pluginPath)
// if pluginName != net.Type {
// return nil, fmt.Errorf("plugin name %q did not match config type %q", pluginName, net.Type)
// }
// for _, e := range environ {
// // Check environment for forced failure request
// parts := strings.Split(e, "=")
// if len(parts) > 0 && parts[0] == "FAIL" {
// return nil, fmt.Errorf("failed to execute plugin %s", pluginName)
// }
// }
// return []byte("{\"CNIVersion\":\"0.4.0\"}"), nil
//}
//
//func (f *fakeExec) FindInPath(plugin string, paths []string) (string, error) {
// if len(paths) > 0 {
// return path.Join(paths[0], plugin), nil
// }
// return "", fmt.Errorf("failed to find plugin %s in paths %v", plugin, paths)
//}
func ExecPluginWithResult(ctx context.Context, pluginPath string, netconf []byte, args CNIArgs, exec Exec) (types.Result, error) {
if exec == nil {
exec = defaultExec
}
stdoutBytes, err := exec.ExecPlugin(ctx, pluginPath, netconf, args.AsEnv())
if err != nil {
return nil, err
}
resultVersion, fixedBytes, err := fixupResultVersion(netconf, stdoutBytes)
if err != nil {
return nil, err
}
return create.Create(resultVersion, fixedBytes)
}
func ExecPluginWithoutResult(ctx context.Context, pluginPath string, netconf []byte, args CNIArgs, exec Exec) error {
if exec == nil {
exec = defaultExec
}
_, err := exec.ExecPlugin(ctx, pluginPath, netconf, args.AsEnv())
return err
}
// GetVersionInfo returns the version information available about the plugin.
// For recent-enough plugins, it uses the information returned by the VERSION
// command. For older plugins which do not recognize that command, it reports
// version 0.1.0
func GetVersionInfo(ctx context.Context, pluginPath string, exec Exec) (version.PluginInfo, error) {
if exec == nil {
exec = defaultExec
}
args := &Args{
Command: "VERSION",
// set fake values required by plugins built against an older version of skel
NetNS: "dummy",
IfName: "dummy",
Path: "dummy",
}
stdin := []byte(fmt.Sprintf(`{"cniVersion":%q}`, version.Current()))
stdoutBytes, err := exec.ExecPlugin(ctx, pluginPath, stdin, args.AsEnv())
if err != nil {
if err.Error() == "unknown CNI_COMMAND: VERSION" {
return version.PluginSupports("0.1.0"), nil
}
return nil, err
}
return exec.Decode(stdoutBytes)
}
// DefaultExec is an object that implements the Exec interface which looks
// for and executes plugins from disk.
type DefaultExec struct {
*RawExec
version.PluginDecoder
}
// DefaultExec implements the Exec interface
var _ Exec = &DefaultExec{}
var defaultExec = &DefaultExec{
RawExec: &RawExec{Stderr: os.Stderr},
}
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