Vendor Update (#14496)

* update code.gitea.io/sdk/gitea v0.13.1 -> v0.13.2

* update github.com/go-swagger/go-swagger v0.25.0 -> v0.26.0

* update github.com/google/uuid v1.1.2 -> v1.2.0

* update github.com/klauspost/compress v1.11.3 -> v1.11.7

* update github.com/lib/pq 083382b7e6fc -> v1.9.0

* update github.com/markbates/goth v1.65.0 -> v1.66.1

* update github.com/mattn/go-sqlite3 v1.14.4 -> v1.14.6

* update github.com/mgechev/revive 246eac737dc7 -> v1.0.3

* update github.com/minio/minio-go/v7 v7.0.6 -> v7.0.7

* update github.com/niklasfasching/go-org v1.3.2 -> v1.4.0

* update github.com/olivere/elastic/v7 v7.0.21 -> v7.0.22

* update github.com/pquerna/otp v1.2.0 -> v1.3.0

* update github.com/xanzy/go-gitlab v0.39.0 -> v0.42.0

* update github.com/yuin/goldmark v1.2.1 -> v1.3.1

vendor/golang.org/x/oauth2/README.md

@@ -1,7 +1,7 @@
 # OAuth2 for Go
 
+[![Go Reference](https://pkg.go.dev/badge/golang.org/x/oauth2.svg)](https://pkg.go.dev/golang.org/x/oauth2)
 [![Build Status](https://travis-ci.org/golang/oauth2.svg?branch=master)](https://travis-ci.org/golang/oauth2)
-[![GoDoc](https://godoc.org/golang.org/x/oauth2?status.svg)](https://godoc.org/golang.org/x/oauth2)
 
 oauth2 package contains a client implementation for OAuth 2.0 spec.
 
@@ -14,17 +14,17 @@ go get golang.org/x/oauth2
 Or you can manually git clone the repository to
 `$(go env GOPATH)/src/golang.org/x/oauth2`.
 
-See godoc for further documentation and examples.
+See pkg.go.dev for further documentation and examples.
 
-* [godoc.org/golang.org/x/oauth2](https://godoc.org/golang.org/x/oauth2)
-* [godoc.org/golang.org/x/oauth2/google](https://godoc.org/golang.org/x/oauth2/google)
+* [pkg.go.dev/golang.org/x/oauth2](https://pkg.go.dev/golang.org/x/oauth2)
+* [pkg.go.dev/golang.org/x/oauth2/google](https://pkg.go.dev/golang.org/x/oauth2/google)
 
 ## Policy for new packages
 
 We no longer accept new provider-specific packages in this repo if all
 they do is add a single endpoint variable. If you just want to add a
 single endpoint, add it to the
-[godoc.org/golang.org/x/oauth2/endpoints](https://godoc.org/golang.org/x/oauth2/endpoints)
+[pkg.go.dev/golang.org/x/oauth2/endpoints](https://pkg.go.dev/golang.org/x/oauth2/endpoints)
 package.
 
 ## Report Issues / Send Patches

vendor/golang.org/x/oauth2/google/google.go

@@ -15,6 +15,7 @@ import (
 
 	"cloud.google.com/go/compute/metadata"
 	"golang.org/x/oauth2"
+	"golang.org/x/oauth2/google/internal/externalaccount"
 	"golang.org/x/oauth2/jwt"
 )
 
@@ -93,6 +94,7 @@ func JWTConfigFromJSON(jsonKey []byte, scope ...string) (*jwt.Config, error) {
 const (
 	serviceAccountKey  = "service_account"
 	userCredentialsKey = "authorized_user"
+	externalAccountKey = "external_account"
 )
 
 // credentialsFile is the unmarshalled representation of a credentials file.
@@ -111,6 +113,15 @@ type credentialsFile struct {
 	ClientSecret string `json:"client_secret"`
 	ClientID     string `json:"client_id"`
 	RefreshToken string `json:"refresh_token"`
+
+	// External Account fields
+	Audience                       string                           `json:"audience"`
+	SubjectTokenType               string                           `json:"subject_token_type"`
+	TokenURLExternal               string                           `json:"token_url"`
+	TokenInfoURL                   string                           `json:"token_info_url"`
+	ServiceAccountImpersonationURL string                           `json:"service_account_impersonation_url"`
+	CredentialSource               externalaccount.CredentialSource `json:"credential_source"`
+	QuotaProjectID                 string                           `json:"quota_project_id"`
 }
 
 func (f *credentialsFile) jwtConfig(scopes []string) *jwt.Config {
@@ -141,6 +152,20 @@ func (f *credentialsFile) tokenSource(ctx context.Context, scopes []string) (oau
 		}
 		tok := &oauth2.Token{RefreshToken: f.RefreshToken}
 		return cfg.TokenSource(ctx, tok), nil
+	case externalAccountKey:
+		cfg := &externalaccount.Config{
+			Audience:                       f.Audience,
+			SubjectTokenType:               f.SubjectTokenType,
+			TokenURL:                       f.TokenURLExternal,
+			TokenInfoURL:                   f.TokenInfoURL,
+			ServiceAccountImpersonationURL: f.ServiceAccountImpersonationURL,
+			ClientSecret:                   f.ClientSecret,
+			ClientID:                       f.ClientID,
+			CredentialSource:               f.CredentialSource,
+			QuotaProjectID:                 f.QuotaProjectID,
+			Scopes:                         scopes,
+		}
+		return cfg.TokenSource(ctx), nil
 	case "":
 		return nil, errors.New("missing 'type' field in credentials")
 	default:

vendor/golang.org/x/oauth2/google/internal/externalaccount/aws.go

@@ -0,0 +1,230 @@
+// Copyright 2021 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.
+
+package externalaccount
+
+import (
+	"crypto/hmac"
+	"crypto/sha256"
+	"encoding/hex"
+	"errors"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"net/http"
+	"path"
+	"sort"
+	"strings"
+	"time"
+)
+
+// RequestSigner is a utility class to sign http requests using a AWS V4 signature.
+type awsRequestSigner struct {
+	RegionName             string
+	AwsSecurityCredentials map[string]string
+}
+
+const (
+// AWS Signature Version 4 signing algorithm identifier.
+	awsAlgorithm = "AWS4-HMAC-SHA256"
+
+// The termination string for the AWS credential scope value as defined in
+// https://docs.aws.amazon.com/general/latest/gr/sigv4-create-string-to-sign.html
+	awsRequestType = "aws4_request"
+
+// The AWS authorization header name for the security session token if available.
+	awsSecurityTokenHeader = "x-amz-security-token"
+
+// The AWS authorization header name for the auto-generated date.
+	awsDateHeader = "x-amz-date"
+
+	awsTimeFormatLong = "20060102T150405Z"
+	awsTimeFormatShort = "20060102"
+)
+
+func getSha256(input []byte) (string, error) {
+	hash := sha256.New()
+	if _, err := hash.Write(input); err != nil {
+		return "", err
+	}
+	return hex.EncodeToString(hash.Sum(nil)), nil
+}
+
+func getHmacSha256(key, input []byte) ([]byte, error) {
+	hash := hmac.New(sha256.New, key)
+	if _, err := hash.Write(input); err != nil {
+		return nil, err
+	}
+	return hash.Sum(nil), nil
+}
+
+func cloneRequest(r *http.Request) *http.Request {
+	r2 := new(http.Request)
+	*r2 = *r
+	if r.Header != nil {
+		r2.Header = make(http.Header, len(r.Header))
+
+		// Find total number of values.
+		headerCount := 0
+		for _, headerValues := range r.Header {
+			headerCount += len(headerValues)
+		}
+		copiedHeaders := make([]string, headerCount) // shared backing array for headers' values
+
+		for headerKey, headerValues := range r.Header {
+			headerCount = copy(copiedHeaders, headerValues)
+			r2.Header[headerKey] = copiedHeaders[:headerCount:headerCount]
+			copiedHeaders = copiedHeaders[headerCount:]
+		}
+	}
+	return r2
+}
+
+func canonicalPath(req *http.Request) string {
+	result := req.URL.EscapedPath()
+	if result == "" {
+		return "/"
+	}
+	return path.Clean(result)
+}
+
+func canonicalQuery(req *http.Request) string {
+	queryValues := req.URL.Query()
+	for queryKey := range queryValues {
+		sort.Strings(queryValues[queryKey])
+	}
+	return queryValues.Encode()
+}
+
+func canonicalHeaders(req *http.Request) (string, string) {
+	// Header keys need to be sorted alphabetically.
+	var headers []string
+	lowerCaseHeaders := make(http.Header)
+	for k, v := range req.Header {
+		k := strings.ToLower(k)
+		if _, ok := lowerCaseHeaders[k]; ok {
+			// include additional values
+			lowerCaseHeaders[k] = append(lowerCaseHeaders[k], v...)
+		} else {
+			headers = append(headers, k)
+			lowerCaseHeaders[k] = v
+		}
+	}
+	sort.Strings(headers)
+
+	var fullHeaders strings.Builder
+	for _, header := range headers {
+		headerValue := strings.Join(lowerCaseHeaders[header], ",")
+		fullHeaders.WriteString(header)
+		fullHeaders.WriteRune(':')
+		fullHeaders.WriteString(headerValue)
+		fullHeaders.WriteRune('\n')
+	}
+
+	return strings.Join(headers, ";"), fullHeaders.String()
+}
+
+func requestDataHash(req *http.Request) (string, error) {
+	var requestData []byte
+	if req.Body != nil {
+		requestBody, err := req.GetBody()
+		if err != nil {
+			return "", err
+		}
+		defer requestBody.Close()
+
+		requestData, err = ioutil.ReadAll(io.LimitReader(requestBody, 1<<20))
+		if err != nil {
+			return "", err
+		}
+	}
+
+	return getSha256(requestData)
+}
+
+func requestHost(req *http.Request) string {
+	if req.Host != "" {
+		return req.Host
+	}
+	return req.URL.Host
+}
+
+func canonicalRequest(req *http.Request, canonicalHeaderColumns, canonicalHeaderData string) (string, error) {
+	dataHash, err := requestDataHash(req)
+	if err != nil {
+		return "", err
+	}
+
+	return fmt.Sprintf("%s\n%s\n%s\n%s\n%s\n%s", req.Method, canonicalPath(req), canonicalQuery(req), canonicalHeaderData, canonicalHeaderColumns, dataHash), nil
+}
+
+// SignRequest adds the appropriate headers to an http.Request
+// or returns an error if something prevented this.
+func (rs *awsRequestSigner) SignRequest(req *http.Request) error {
+	signedRequest := cloneRequest(req)
+	timestamp := now()
+
+	signedRequest.Header.Add("host", requestHost(req))
+
+	if securityToken, ok := rs.AwsSecurityCredentials["security_token"]; ok {
+		signedRequest.Header.Add(awsSecurityTokenHeader, securityToken)
+	}
+
+	if signedRequest.Header.Get("date") == "" {
+		signedRequest.Header.Add(awsDateHeader, timestamp.Format(awsTimeFormatLong))
+	}
+
+	authorizationCode, err := rs.generateAuthentication(signedRequest, timestamp)
+	if err != nil {
+		return err
+	}
+	signedRequest.Header.Set("Authorization", authorizationCode)
+
+	req.Header = signedRequest.Header
+	return nil
+}
+
+func (rs *awsRequestSigner) generateAuthentication(req *http.Request, timestamp time.Time) (string, error) {
+	secretAccessKey, ok := rs.AwsSecurityCredentials["secret_access_key"]
+	if !ok {
+		return "", errors.New("oauth2/google: missing secret_access_key header")
+	}
+	accessKeyId, ok := rs.AwsSecurityCredentials["access_key_id"]
+	if !ok {
+		return "", errors.New("oauth2/google: missing access_key_id header")
+	}
+
+	canonicalHeaderColumns, canonicalHeaderData := canonicalHeaders(req)
+
+	dateStamp := timestamp.Format(awsTimeFormatShort)
+	serviceName := ""
+	if splitHost := strings.Split(requestHost(req), "."); len(splitHost) > 0 {
+		serviceName = splitHost[0]
+	}
+
+	credentialScope := fmt.Sprintf("%s/%s/%s/%s",dateStamp, rs.RegionName, serviceName, awsRequestType)
+
+	requestString, err := canonicalRequest(req, canonicalHeaderColumns, canonicalHeaderData)
+	if err != nil {
+		return "", err
+	}
+	requestHash, err := getSha256([]byte(requestString))
+	if err != nil{
+		return "", err
+	}
+
+	stringToSign := fmt.Sprintf("%s\n%s\n%s\n%s", awsAlgorithm, timestamp.Format(awsTimeFormatLong), credentialScope, requestHash)
+
+	signingKey := []byte("AWS4" + secretAccessKey)
+	for _, signingInput := range []string{
+		dateStamp, rs.RegionName, serviceName, awsRequestType, stringToSign,
+	} {
+		signingKey, err = getHmacSha256(signingKey, []byte(signingInput))
+		if err != nil{
+			return "", err
+		}
+	}
+
+	return fmt.Sprintf("%s Credential=%s/%s, SignedHeaders=%s, Signature=%s", awsAlgorithm, accessKeyId, credentialScope, canonicalHeaderColumns, hex.EncodeToString(signingKey)), nil
+}

vendor/golang.org/x/oauth2/google/internal/externalaccount/basecredentials.go

@@ -0,0 +1,145 @@
+// Copyright 2020 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.
+
+package externalaccount
+
+import (
+	"context"
+	"fmt"
+	"golang.org/x/oauth2"
+	"net/http"
+	"time"
+)
+
+// now aliases time.Now for testing
+var now = time.Now
+
+// Config stores the configuration for fetching tokens with external credentials.
+type Config struct {
+	Audience                       string
+	SubjectTokenType               string
+	TokenURL                       string
+	TokenInfoURL                   string
+	ServiceAccountImpersonationURL string
+	ClientSecret                   string
+	ClientID                       string
+	CredentialSource               CredentialSource
+	QuotaProjectID                 string
+	Scopes                         []string
+}
+
+// TokenSource Returns an external account TokenSource struct. This is to be called by package google to construct a google.Credentials.
+func (c *Config) TokenSource(ctx context.Context) oauth2.TokenSource {
+	ts := tokenSource{
+		ctx:  ctx,
+		conf: c,
+	}
+	if c.ServiceAccountImpersonationURL == "" {
+		return oauth2.ReuseTokenSource(nil, ts)
+	}
+	scopes := c.Scopes
+	ts.conf.Scopes = []string{"https://www.googleapis.com/auth/cloud-platform"}
+	imp := impersonateTokenSource{
+		ctx:    ctx,
+		url:    c.ServiceAccountImpersonationURL,
+		scopes: scopes,
+		ts: oauth2.ReuseTokenSource(nil, ts),
+	}
+	return oauth2.ReuseTokenSource(nil, imp)
+}
+
+// Subject token file types.
+const (
+	fileTypeText = "text"
+	fileTypeJSON = "json"
+)
+
+type format struct {
+	// Type is either "text" or "json".  When not provided "text" type is assumed.
+	Type string `json:"type"`
+	// SubjectTokenFieldName is only required for JSON format.  This would be "access_token" for azure.
+	SubjectTokenFieldName string `json:"subject_token_field_name"`
+}
+
+// CredentialSource stores the information necessary to retrieve the credentials for the STS exchange.
+type CredentialSource struct {
+	File string `json:"file"`
+
+	URL     string            `json:"url"`
+	Headers map[string]string `json:"headers"`
+
+	EnvironmentID               string `json:"environment_id"`
+	RegionURL                   string `json:"region_url"`
+	RegionalCredVerificationURL string `json:"regional_cred_verification_url"`
+	CredVerificationURL         string `json:"cred_verification_url"`
+	Format                      format `json:"format"`
+}
+
+// parse determines the type of CredentialSource needed
+func (c *Config) parse(ctx context.Context) baseCredentialSource {
+	if c.CredentialSource.File != "" {
+		return fileCredentialSource{File: c.CredentialSource.File, Format: c.CredentialSource.Format}
+	} else if c.CredentialSource.URL != "" {
+		return urlCredentialSource{URL: c.CredentialSource.URL, Format: c.CredentialSource.Format, ctx: ctx}
+	}
+	return nil
+}
+
+type baseCredentialSource interface {
+	subjectToken() (string, error)
+}
+
+// tokenSource is the source that handles external credentials.
+type tokenSource struct {
+	ctx  context.Context
+	conf *Config
+}
+
+// Token allows tokenSource to conform to the oauth2.TokenSource interface.
+func (ts tokenSource) Token() (*oauth2.Token, error) {
+	conf := ts.conf
+
+	credSource := conf.parse(ts.ctx)
+	if credSource == nil {
+		return nil, fmt.Errorf("oauth2/google: unable to parse credential source")
+	}
+	subjectToken, err := credSource.subjectToken()
+	if err != nil {
+		return nil, err
+	}
+	stsRequest := STSTokenExchangeRequest{
+		GrantType:          "urn:ietf:params:oauth:grant-type:token-exchange",
+		Audience:           conf.Audience,
+		Scope:              conf.Scopes,
+		RequestedTokenType: "urn:ietf:params:oauth:token-type:access_token",
+		SubjectToken:       subjectToken,
+		SubjectTokenType:   conf.SubjectTokenType,
+	}
+	header := make(http.Header)
+	header.Add("Content-Type", "application/x-www-form-urlencoded")
+	clientAuth := ClientAuthentication{
+		AuthStyle:    oauth2.AuthStyleInHeader,
+		ClientID:     conf.ClientID,
+		ClientSecret: conf.ClientSecret,
+	}
+	stsResp, err := ExchangeToken(ts.ctx, conf.TokenURL, &stsRequest, clientAuth, header, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	accessToken := &oauth2.Token{
+		AccessToken: stsResp.AccessToken,
+		TokenType:   stsResp.TokenType,
+	}
+	if stsResp.ExpiresIn < 0 {
+		return nil, fmt.Errorf("oauth2/google: got invalid expiry from security token service")
+	} else if stsResp.ExpiresIn >= 0 {
+		accessToken.Expiry = now().Add(time.Duration(stsResp.ExpiresIn) * time.Second)
+	}
+
+	if stsResp.RefreshToken != "" {
+		accessToken.RefreshToken = stsResp.RefreshToken
+	}
+	return accessToken, nil
+}

vendor/golang.org/x/oauth2/google/internal/externalaccount/clientauth.go

@@ -0,0 +1,41 @@
+// Copyright 2020 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.
+
+package externalaccount
+
+import (
+	"encoding/base64"
+	"golang.org/x/oauth2"
+	"net/http"
+	"net/url"
+)
+
+// ClientAuthentication represents an OAuth client ID and secret and the mechanism for passing these credentials as stated in rfc6749#2.3.1.
+type ClientAuthentication struct {
+	// AuthStyle can be either basic or request-body
+	AuthStyle    oauth2.AuthStyle
+	ClientID     string
+	ClientSecret string
+}
+
+func (c *ClientAuthentication) InjectAuthentication(values url.Values, headers http.Header) {
+	if c.ClientID == "" || c.ClientSecret == "" || values == nil || headers == nil {
+		return
+	}
+
+	switch c.AuthStyle {
+	case oauth2.AuthStyleInHeader: // AuthStyleInHeader corresponds to basic authentication as defined in rfc7617#2
+		plainHeader := c.ClientID + ":" + c.ClientSecret
+		headers.Add("Authorization", "Basic "+base64.StdEncoding.EncodeToString([]byte(plainHeader)))
+	case oauth2.AuthStyleInParams: // AuthStyleInParams corresponds to request-body authentication with ClientID and ClientSecret in the message body.
+		values.Set("client_id", c.ClientID)
+		values.Set("client_secret", c.ClientSecret)
+	case oauth2.AuthStyleAutoDetect:
+		values.Set("client_id", c.ClientID)
+		values.Set("client_secret", c.ClientSecret)
+	default:
+		values.Set("client_id", c.ClientID)
+		values.Set("client_secret", c.ClientSecret)
+	}
+}

vendor/golang.org/x/oauth2/google/internal/externalaccount/err.go

@@ -0,0 +1,18 @@
+// Copyright 2020 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.
+
+package externalaccount
+
+import "fmt"
+
+// Error for handling OAuth related error responses as stated in rfc6749#5.2.
+type Error struct {
+	Code        string
+	URI         string
+	Description string
+}
+
+func (err *Error) Error() string {
+	return fmt.Sprintf("got error code %s from %s: %s", err.Code, err.URI, err.Description)
+}

vendor/golang.org/x/oauth2/google/internal/externalaccount/filecredsource.go

@@ -0,0 +1,57 @@
+// Copyright 2020 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.
+
+package externalaccount
+
+import (
+	"bytes"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"os"
+)
+
+type fileCredentialSource struct {
+	File   string
+	Format format
+}
+
+func (cs fileCredentialSource) subjectToken() (string, error) {
+	tokenFile, err := os.Open(cs.File)
+	if err != nil {
+		return "", fmt.Errorf("oauth2/google: failed to open credential file %q", cs.File)
+	}
+	defer tokenFile.Close()
+	tokenBytes, err := ioutil.ReadAll(io.LimitReader(tokenFile, 1<<20))
+	if err != nil {
+		return "", fmt.Errorf("oauth2/google: failed to read credential file: %v", err)
+	}
+	tokenBytes = bytes.TrimSpace(tokenBytes)
+	switch cs.Format.Type {
+	case "json":
+		jsonData := make(map[string]interface{})
+		err = json.Unmarshal(tokenBytes, &jsonData)
+		if err != nil {
+			return "", fmt.Errorf("oauth2/google: failed to unmarshal subject token file: %v", err)
+		}
+		val, ok := jsonData[cs.Format.SubjectTokenFieldName]
+		if !ok {
+			return "", errors.New("oauth2/google: provided subject_token_field_name not found in credentials")
+		}
+		token, ok := val.(string)
+		if !ok {
+			return "", errors.New("oauth2/google: improperly formatted subject token")
+		}
+		return token, nil
+	case "text":
+		return string(tokenBytes), nil
+	case "":
+		return string(tokenBytes), nil
+	default:
+		return "", errors.New("oauth2/google: invalid credential_source file format type")
+	}
+
+}

vendor/golang.org/x/oauth2/google/internal/externalaccount/impersonate.go

@@ -0,0 +1,83 @@
+// Copyright 2021 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.
+
+package externalaccount
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"fmt"
+	"golang.org/x/oauth2"
+	"io"
+	"io/ioutil"
+	"net/http"
+	"time"
+)
+
+// generateAccesstokenReq is used for service account impersonation
+type generateAccessTokenReq struct {
+	Delegates []string `json:"delegates,omitempty"`
+	Lifetime  string   `json:"lifetime,omitempty"`
+	Scope     []string `json:"scope,omitempty"`
+}
+
+type impersonateTokenResponse struct {
+	AccessToken string `json:"accessToken"`
+	ExpireTime  string `json:"expireTime"`
+}
+
+type impersonateTokenSource struct {
+	ctx context.Context
+	ts  oauth2.TokenSource
+
+	url    string
+	scopes []string
+}
+
+// Token performs the exchange to get a temporary service account
+func (its impersonateTokenSource) Token() (*oauth2.Token, error) {
+	reqBody := generateAccessTokenReq{
+		Lifetime: "3600s",
+		Scope:    its.scopes,
+	}
+	b, err := json.Marshal(reqBody)
+	if err != nil {
+		return nil, fmt.Errorf("oauth2/google: unable to marshal request: %v", err)
+	}
+	client := oauth2.NewClient(its.ctx, its.ts)
+	req, err := http.NewRequest("POST", its.url, bytes.NewReader(b))
+	if err != nil {
+		return nil, fmt.Errorf("oauth2/google: unable to create impersonation request: %v", err)
+	}
+	req = req.WithContext(its.ctx)
+	req.Header.Set("Content-Type", "application/json")
+
+	resp, err := client.Do(req)
+	if err != nil {
+		return nil, fmt.Errorf("oauth2/google: unable to generate access token: %v", err)
+	}
+	defer resp.Body.Close()
+	body, err := ioutil.ReadAll(io.LimitReader(resp.Body, 1<<20))
+	if err != nil {
+		return nil, fmt.Errorf("oauth2/google: unable to read body: %v", err)
+	}
+	if c := resp.StatusCode; c < 200 || c > 299 {
+		return nil, fmt.Errorf("oauth2/google: status code %d: %s", c, body)
+	}
+
+	var accessTokenResp impersonateTokenResponse
+	if err := json.Unmarshal(body, &accessTokenResp); err != nil {
+		return nil, fmt.Errorf("oauth2/google: unable to parse response: %v", err)
+	}
+	expiry, err := time.Parse(time.RFC3339, accessTokenResp.ExpireTime)
+	if err != nil {
+		return nil, fmt.Errorf("oauth2/google: unable to parse expiry: %v", err)
+	}
+	return &oauth2.Token{
+		AccessToken: accessTokenResp.AccessToken,
+		Expiry:      expiry,
+		TokenType:   "Bearer",
+	}, nil
+}

vendor/golang.org/x/oauth2/google/internal/externalaccount/sts_exchange.go

@@ -0,0 +1,98 @@
+// Copyright 2020 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.
+
+package externalaccount
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"net/url"
+	"strconv"
+	"strings"
+
+	"golang.org/x/oauth2"
+)
+
+// ExchangeToken performs an oauth2 token exchange with the provided endpoint.
+// The first 4 fields are all mandatory.  headers can be used to pass additional
+// headers beyond the bare minimum required by the token exchange.  options can
+// be used to pass additional JSON-structured options to the remote server.
+func ExchangeToken(ctx context.Context, endpoint string, request *STSTokenExchangeRequest, authentication ClientAuthentication, headers http.Header, options map[string]interface{}) (*STSTokenExchangeResponse, error) {
+
+	client := oauth2.NewClient(ctx, nil)
+
+	data := url.Values{}
+	data.Set("audience", request.Audience)
+	data.Set("grant_type", "urn:ietf:params:oauth:grant-type:token-exchange")
+	data.Set("requested_token_type", "urn:ietf:params:oauth:token-type:access_token")
+	data.Set("subject_token_type", request.SubjectTokenType)
+	data.Set("subject_token", request.SubjectToken)
+	data.Set("scope", strings.Join(request.Scope, " "))
+	opts, err := json.Marshal(options)
+	if err != nil {
+		return nil, fmt.Errorf("oauth2/google: failed to marshal additional options: %v", err)
+	}
+	data.Set("options", string(opts))
+
+	authentication.InjectAuthentication(data, headers)
+	encodedData := data.Encode()
+
+	req, err := http.NewRequest("POST", endpoint, strings.NewReader(encodedData))
+	if err != nil {
+		return nil, fmt.Errorf("oauth2/google: failed to properly build http request: %v", err)
+
+	}
+	req = req.WithContext(ctx)
+	for key, list := range headers {
+		for _, val := range list {
+			req.Header.Add(key, val)
+		}
+	}
+	req.Header.Add("Content-Length", strconv.Itoa(len(encodedData)))
+
+	resp, err := client.Do(req)
+
+	if err != nil {
+		return nil, fmt.Errorf("oauth2/google: invalid response from Secure Token Server: %v", err)
+	}
+	defer resp.Body.Close()
+
+	bodyJson := json.NewDecoder(io.LimitReader(resp.Body, 1<<20))
+	var stsResp STSTokenExchangeResponse
+	err = bodyJson.Decode(&stsResp)
+	if err != nil {
+		return nil, fmt.Errorf("oauth2/google: failed to unmarshal response body from Secure Token Server: %v", err)
+
+	}
+
+	return &stsResp, nil
+}
+
+// STSTokenExchangeRequest contains fields necessary to make an oauth2 token exchange.
+type STSTokenExchangeRequest struct {
+	ActingParty struct {
+		ActorToken     string
+		ActorTokenType string
+	}
+	GrantType          string
+	Resource           string
+	Audience           string
+	Scope              []string
+	RequestedTokenType string
+	SubjectToken       string
+	SubjectTokenType   string
+}
+
+// STSTokenExchangeResponse is used to decode the remote server response during an oauth2 token exchange.
+type STSTokenExchangeResponse struct {
+	AccessToken     string `json:"access_token"`
+	IssuedTokenType string `json:"issued_token_type"`
+	TokenType       string `json:"token_type"`
+	ExpiresIn       int    `json:"expires_in"`
+	Scope           string `json:"scope"`
+	RefreshToken    string `json:"refresh_token"`
+}

vendor/golang.org/x/oauth2/google/internal/externalaccount/urlcredsource.go

@@ -0,0 +1,71 @@
+// Copyright 2020 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.
+
+package externalaccount
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"golang.org/x/oauth2"
+	"io"
+	"io/ioutil"
+	"net/http"
+)
+
+type urlCredentialSource struct {
+	URL     string
+	Headers map[string]string
+	Format  format
+	ctx     context.Context
+}
+
+func (cs urlCredentialSource) subjectToken() (string, error) {
+	client := oauth2.NewClient(cs.ctx, nil)
+	req, err := http.NewRequest("GET", cs.URL, nil)
+	if err != nil {
+		return "", fmt.Errorf("oauth2/google: HTTP request for URL-sourced credential failed: %v", err)
+	}
+	req = req.WithContext(cs.ctx)
+
+	for key, val := range cs.Headers {
+		req.Header.Add(key, val)
+	}
+	resp, err := client.Do(req)
+	if err != nil {
+		return "", fmt.Errorf("oauth2/google: invalid response when retrieving subject token: %v", err)
+	}
+	defer resp.Body.Close()
+
+	tokenBytes, err := ioutil.ReadAll(io.LimitReader(resp.Body, 1<<20))
+	if err != nil {
+		return "", fmt.Errorf("oauth2/google: invalid body in subject token URL query: %v", err)
+	}
+
+	switch cs.Format.Type {
+	case "json":
+		jsonData := make(map[string]interface{})
+		err = json.Unmarshal(tokenBytes, &jsonData)
+		if err != nil {
+			return "", fmt.Errorf("oauth2/google: failed to unmarshal subject token file: %v", err)
+		}
+		val, ok := jsonData[cs.Format.SubjectTokenFieldName]
+		if !ok {
+			return "", errors.New("oauth2/google: provided subject_token_field_name not found in credentials")
+		}
+		token, ok := val.(string)
+		if !ok {
+			return "", errors.New("oauth2/google: improperly formatted subject token")
+		}
+		return token, nil
+	case "text":
+		return string(tokenBytes), nil
+	case "":
+		return string(tokenBytes), nil
+	default:
+		return "", errors.New("oauth2/google: invalid credential_source file format type")
+	}
+
+}