oauth2/google/appengine_gen1.go

91 lines
2.5 KiB
Go

// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// +build appengine
package google
import (
"sort"
"strings"
"sync"
"golang.org/x/net/context"
"golang.org/x/oauth2"
"google.golang.org/appengine"
)
func init() {
appengineTokenFunc = appengine.AccessToken
appengineAppIDFunc = appengine.AppID
}
// AppEngineTokenSource returns a token source that fetches tokens from either
// the current application's service account or from the metadata server,
// depending on the App Engine environment. See below for environment-specific
// details. If you are implementing a 3-legged OAuth 2.0 flow on App Engine that
// involves user accounts, see oauth2.Config instead.
//
// First generation App Engine runtimes (<= Go 1.9):
// AppEngineTokenSource returns a token source that fetches tokens issued to the
// current App Engine application's service account. The provided context must have
// come from appengine.NewContext.
//
// Second generation App Engine runtimes (>= Go 1.11) and App Engine flexible:
// AppEngineTokenSource is DEPRECATED on second generation runtimes and on the
// flexible environment. It delegates to ComputeTokenSource, and the provided
// context and scopes are not used. Please use DefaultTokenSource (or ComputeTokenSource,
// which DefaultTokenSource will use in this case) instead.
func AppEngineTokenSource(ctx context.Context, scope ...string) oauth2.TokenSource {
scopes := append([]string{}, scope...)
sort.Strings(scopes)
return &appEngineTokenSource{
ctx: ctx,
scopes: scopes,
key: strings.Join(scopes, " "),
}
}
// aeTokens helps the fetched tokens to be reused until their expiration.
var (
aeTokensMu sync.Mutex
aeTokens = make(map[string]*tokenLock) // key is space-separated scopes
)
type tokenLock struct {
mu sync.Mutex // guards t; held while fetching or updating t
t *oauth2.Token
}
type appEngineTokenSource struct {
ctx context.Context
scopes []string
key string // to aeTokens map; space-separated scopes
}
func (ts *appEngineTokenSource) Token() (*oauth2.Token, error) {
aeTokensMu.Lock()
tok, ok := aeTokens[ts.key]
if !ok {
tok = &tokenLock{}
aeTokens[ts.key] = tok
}
aeTokensMu.Unlock()
tok.mu.Lock()
defer tok.mu.Unlock()
if tok.t.Valid() {
return tok.t, nil
}
access, exp, err := appengineTokenFunc(ts.ctx, ts.scopes...)
if err != nil {
return nil, err
}
tok.t = &oauth2.Token{
AccessToken: access,
Expiry: exp,
}
return tok.t, nil
}