plugin/token_source.go

// Copyright 2019 The Kubernetes 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 plugin

import (
	"context"
	"encoding/json"
	"net/http"
	"strings"
	"time"

	"golang.org/x/oauth2"
	"golang.org/x/oauth2/google"
	"google.golang.org/api/googleapi"
)

// altTokenSource is the structure holding the data for the functionality needed to generates tokens
type altTokenSource struct {
	oauthClient *http.Client
	tokenURL    string
	tokenBody   string
}

// Token returns a token which may be used for authentication
func (a *altTokenSource) Token() (*oauth2.Token, error) {
	req, err := http.NewRequest("POST", a.tokenURL, strings.NewReader(a.tokenBody))
	if err != nil {
		return nil, err
	}
	res, err := a.oauthClient.Do(req)
	if err != nil {
		return nil, err
	}
	defer res.Body.Close()
	if err := googleapi.CheckResponse(res); err != nil {
		return nil, err
	}
	var tok struct {
		AccessToken string    `json:"accessToken"`
		ExpireTime  time.Time `json:"expireTime"`
	}
	if err := json.NewDecoder(res.Body).Decode(&tok); err != nil {
		return nil, err
	}
	return &oauth2.Token{
		AccessToken: tok.AccessToken,
		Expiry:      tok.ExpireTime,
	}, nil
}

// newAltTokenSource constructs a new alternate token source for generating tokens.
func newAltTokenSource(ctx context.Context, tokenURL, tokenBody string) oauth2.TokenSource {
	return &altTokenSource{
		oauthClient: oauth2.NewClient(ctx, google.ComputeTokenSource("")),
		tokenURL:    tokenURL,
		tokenBody:   tokenBody,
	}
}