75 lines
2.1 KiB
Go
75 lines
2.1 KiB
Go
// Copyright 2015 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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package google
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import (
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"crypto/rsa"
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"fmt"
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"time"
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"golang.org/x/oauth2"
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"golang.org/x/oauth2/internal"
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"golang.org/x/oauth2/jws"
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)
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// JWTAccessTokenSourceFromJSON uses a Google Developers service account JSON
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// key file to read the credentials that authorize and authenticate the
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// requests, and returns a TokenSource that does not use any OAuth2 flow but
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// instead creates a JWT and sends that as the access token.
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// The audience is typically a URL that specifies the scope of the credentials.
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//
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// Note that this is not a standard OAuth flow, but rather an
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// optimization supported by a few Google services.
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// Unless you know otherwise, you should use JWTConfigFromJSON instead.
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func JWTAccessTokenSourceFromJSON(jsonKey []byte, audience string) (oauth2.TokenSource, error) {
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cfg, err := JWTConfigFromJSON(jsonKey)
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if err != nil {
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return nil, fmt.Errorf("google: could not parse JSON key: %v", err)
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}
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pk, err := internal.ParseKey(cfg.PrivateKey)
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if err != nil {
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return nil, fmt.Errorf("google: could not parse key: %v", err)
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}
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ts := &jwtAccessTokenSource{
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email: cfg.Email,
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audience: audience,
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pk: pk,
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pkID: cfg.PrivateKeyID,
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}
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tok, err := ts.Token()
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if err != nil {
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return nil, err
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}
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return oauth2.ReuseTokenSource(tok, ts), nil
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}
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type jwtAccessTokenSource struct {
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email, audience string
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pk *rsa.PrivateKey
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pkID string
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}
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func (ts *jwtAccessTokenSource) Token() (*oauth2.Token, error) {
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iat := time.Now()
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exp := iat.Add(time.Hour)
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cs := &jws.ClaimSet{
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Iss: ts.email,
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Sub: ts.email,
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Aud: ts.audience,
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Iat: iat.Unix(),
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Exp: exp.Unix(),
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}
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hdr := &jws.Header{
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Algorithm: "RS256",
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Typ: "JWT",
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KeyID: string(ts.pkID),
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}
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msg, err := jws.Encode(hdr, cs, ts.pk)
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if err != nil {
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return nil, fmt.Errorf("google: could not encode JWT: %v", err)
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}
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return &oauth2.Token{AccessToken: msg, TokenType: "Bearer", Expiry: exp}, nil
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}
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