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//
// Copyright 2024 The Sigstore 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 handler implements helper functions for plugins written in go. It will extract
// values from PluginArgs and pass them the real SignerVerifier implementation, and then package
// responses into PluginResp.
package handler
import (
"encoding/json"
"errors"
"fmt"
"io"
"github.com/sigstore/sigstore/pkg/signature/kms/cliplugin/common"
"github.com/sigstore/sigstore/pkg/signature/kms/cliplugin/internal/signerverifier"
)
var (
// ErrorPluginArgsParse indicates a problem parsing the plugin args
ErrorPluginArgsParse = errors.New("error parsing plugin args")
// ErrorUnsupportedMethod indicates that an unsupported method name was supplied.
ErrorUnsupportedMethod = errors.New("unsupported method")
)
// GetPluginArgs parses the PluginArgs from the os args.
func GetPluginArgs(osArgs []string) (*common.PluginArgs, error) {
if len(osArgs) < 3 {
return nil, fmt.Errorf("%w: expected at least 3 args, got %d", ErrorPluginArgsParse, len(osArgs))
}
argsStr := osArgs[2]
var args common.PluginArgs
if err := json.Unmarshal([]byte(argsStr), &args); err != nil {
return nil, err
}
return &args, nil
}
// WriteResponse writes JSON-serialized PluginResp to the output.
func WriteResponse(stdout io.Writer, resp *common.PluginResp) error {
enc, err := json.Marshal(resp)
if err != nil {
return err
}
fmt.Fprint(stdout, string(enc))
return nil
}
// WriteErrorResponse writes a response with only an error message to the output.
func WriteErrorResponse(stdout io.Writer, err error) error {
resp := &common.PluginResp{
ErrorMessage: err.Error(),
}
return WriteResponse(stdout, resp)
}
// Dispatch routes to handler functions based on the PluginArgs.
// If there is an error to be returned, it will also call WriteResponse with the error.
func Dispatch(stdout io.Writer, stdin io.Reader, pluginArgs *common.PluginArgs, impl signerverifier.SignerVerifier) (*common.PluginResp, error) {
var resp common.PluginResp
var err error
switch pluginArgs.MethodName {
case common.DefaultAlgorithmMethodName:
resp.DefaultAlgorithm, err = DefaultAlgorithm(stdin, pluginArgs.DefaultAlgorithm, impl)
case common.SupportedAlgorithmsMethodName:
resp.SupportedAlgorithms, err = SupportedAlgorithms(stdin, pluginArgs.SupportedAlgorithms, impl)
case common.CreateKeyMethodName:
resp.CreateKey, err = CreateKey(stdin, pluginArgs.CreateKey, impl)
case common.PublicKeyMethodName:
resp.PublicKey, err = PublicKey(stdin, pluginArgs.PublicKey, impl)
case common.SignMessageMethodName:
resp.SignMessage, err = SignMessage(stdin, pluginArgs.SignMessage, impl)
case common.VerifySignatureMethodName:
resp.VerifySignature, err = VerifySignature(stdin, pluginArgs.VerifySignature, impl)
default:
err = fmt.Errorf("%w: %s", ErrorUnsupportedMethod, pluginArgs.MethodName)
}
if err != nil {
resp.ErrorMessage = err.Error()
}
err = WriteResponse(stdout, &resp)
return &resp, err
}
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