78 lines
1.6 KiB
Go
78 lines
1.6 KiB
Go
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// Copyright 2018 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// +build appengine
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// This file applies to App Engine first generation runtimes (<= Go 1.9).
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package google
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import (
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"context"
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"sort"
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"strings"
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"sync"
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"golang.org/x/oauth2"
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"google.golang.org/appengine"
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)
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func init() {
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appengineTokenFunc = appengine.AccessToken
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appengineAppIDFunc = appengine.AppID
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}
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// See comment on AppEngineTokenSource in appengine.go.
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func appEngineTokenSource(ctx context.Context, scope ...string) oauth2.TokenSource {
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scopes := append([]string{}, scope...)
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sort.Strings(scopes)
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return &gaeTokenSource{
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ctx: ctx,
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scopes: scopes,
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key: strings.Join(scopes, " "),
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}
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}
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// aeTokens helps the fetched tokens to be reused until their expiration.
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var (
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aeTokensMu sync.Mutex
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aeTokens = make(map[string]*tokenLock) // key is space-separated scopes
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)
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type tokenLock struct {
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mu sync.Mutex // guards t; held while fetching or updating t
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t *oauth2.Token
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}
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type gaeTokenSource struct {
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ctx context.Context
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scopes []string
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key string // to aeTokens map; space-separated scopes
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}
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func (ts *gaeTokenSource) Token() (*oauth2.Token, error) {
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aeTokensMu.Lock()
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tok, ok := aeTokens[ts.key]
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if !ok {
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tok = &tokenLock{}
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aeTokens[ts.key] = tok
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}
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aeTokensMu.Unlock()
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tok.mu.Lock()
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defer tok.mu.Unlock()
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if tok.t.Valid() {
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return tok.t, nil
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}
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access, exp, err := appengineTokenFunc(ts.ctx, ts.scopes...)
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if err != nil {
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return nil, err
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}
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tok.t = &oauth2.Token{
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AccessToken: access,
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Expiry: exp,
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}
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return tok.t, nil
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}
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