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// Copyright 2017 Google Inc. All Rights Reserved.
//
// 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 internal
import (
"encoding/json"
"fmt"
"io/ioutil"
"time"
"golang.org/x/net/context"
"golang.org/x/oauth2"
"golang.org/x/oauth2/google"
)
// Creds returns credential information obtained from DialSettings, or if none, then
// it returns default credential information.
func Creds(ctx context.Context, ds *DialSettings) (*google.DefaultCredentials, error) {
if ds.CredentialsFile != "" {
return credFileTokenSource(ctx, ds.CredentialsFile, ds.Scopes...)
}
if ds.TokenSource != nil {
return &google.DefaultCredentials{TokenSource: ds.TokenSource}, nil
}
return google.FindDefaultCredentials(ctx, ds.Scopes...)
}
// credFileTokenSource reads a refresh token file or a service account and returns
// a TokenSource constructed from the config.
func credFileTokenSource(ctx context.Context, filename string, scope ...string) (*google.DefaultCredentials, error) {
data, err := ioutil.ReadFile(filename)
if err != nil {
return nil, fmt.Errorf("cannot read credentials file: %v", err)
}
// See if it is a refresh token credentials file first.
ts, ok, err := refreshTokenTokenSource(ctx, data, scope...)
if err != nil {
return nil, err
}
if ok {
return &google.DefaultCredentials{
TokenSource: ts,
JSON: data,
}, nil
}
// If not, it should be a service account.
cfg, err := google.JWTConfigFromJSON(data, scope...)
if err != nil {
return nil, fmt.Errorf("google.JWTConfigFromJSON: %v", err)
}
// jwt.Config does not expose the project ID, so re-unmarshal to get it.
var pid struct {
ProjectID string `json:"project_id"`
}
if err := json.Unmarshal(data, &pid); err != nil {
return nil, err
}
return &google.DefaultCredentials{
ProjectID: pid.ProjectID,
TokenSource: cfg.TokenSource(ctx),
JSON: data,
}, nil
}
func refreshTokenTokenSource(ctx context.Context, data []byte, scope ...string) (oauth2.TokenSource, bool, error) {
var c cred
if err := json.Unmarshal(data, &c); err != nil {
return nil, false, fmt.Errorf("cannot unmarshal credentials file: %v", err)
}
if c.ClientID == "" || c.ClientSecret == "" || c.RefreshToken == "" || c.Type != "authorized_user" {
return nil, false, nil
}
cfg := &oauth2.Config{
ClientID: c.ClientID,
ClientSecret: c.ClientSecret,
Endpoint: google.Endpoint,
RedirectURL: "urn:ietf:wg:oauth:2.0:oob",
Scopes: scope,
}
return cfg.TokenSource(ctx, &oauth2.Token{
RefreshToken: c.RefreshToken,
Expiry: time.Now(),
}), true, nil
}
type cred struct {
ClientID string `json:"client_id"`
ClientSecret string `json:"client_secret"`
RefreshToken string `json:"refresh_token"`
Type string `json:"type"`
}
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