1 files changed, 128 insertions, 0 deletions
diff --git a/vendor/google.golang.org/api/internal/impersonate/impersonate.go b/vendor/google.golang.org/api/internal/impersonate/impersonate.go
new file mode 100644
index 0000000..b465bbc
--- /dev/null
+++ b/vendor/google.golang.org/api/internal/impersonate/impersonate.go
@@ -0,0 +1,128 @@
+// 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 impersonate is used to impersonate Google Credentials.
+package impersonate
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"net/http"
+	"time"
+
+	"golang.org/x/oauth2"
+)
+
+// Config for generating impersonated credentials.
+type Config struct {
+	// Target is the service account to impersonate. Required.
+	Target string
+	// Scopes the impersonated credential should have. Required.
+	Scopes []string
+	// Delegates are the service accounts in a delegation chain. Each service
+	// account must be granted roles/iam.serviceAccountTokenCreator on the next
+	// service account in the chain. Optional.
+	Delegates []string
+}
+
+// TokenSource returns an impersonated TokenSource configured with the provided
+// config using ts as the base credential provider for making requests.
+func TokenSource(ctx context.Context, ts oauth2.TokenSource, config *Config) (oauth2.TokenSource, error) {
+	if len(config.Scopes) == 0 {
+		return nil, fmt.Errorf("impersonate: scopes must be provided")
+	}
+	its := impersonatedTokenSource{
+		ctx:  ctx,
+		ts:   ts,
+		name: formatIAMServiceAccountName(config.Target),
+		// Default to the longest acceptable value of one hour as the token will
+		// be refreshed automatically.
+		lifetime: "3600s",
+	}
+
+	its.delegates = make([]string, len(config.Delegates))
+	for i, v := range config.Delegates {
+		its.delegates[i] = formatIAMServiceAccountName(v)
+	}
+	its.scopes = make([]string, len(config.Scopes))
+	copy(its.scopes, config.Scopes)
+
+	return oauth2.ReuseTokenSource(nil, its), nil
+}
+
+func formatIAMServiceAccountName(name string) string {
+	return fmt.Sprintf("projects/-/serviceAccounts/%s", name)
+}
+
+type generateAccessTokenReq struct {
+	Delegates []string `json:"delegates,omitempty"`
+	Lifetime  string   `json:"lifetime,omitempty"`
+	Scope     []string `json:"scope,omitempty"`
+}
+
+type generateAccessTokenResp struct {
+	AccessToken string `json:"accessToken"`
+	ExpireTime  string `json:"expireTime"`
+}
+
+type impersonatedTokenSource struct {
+	ctx context.Context
+	ts  oauth2.TokenSource
+
+	name      string
+	lifetime  string
+	scopes    []string
+	delegates []string
+}
+
+// Token returns an impersonated Token.
+func (i impersonatedTokenSource) Token() (*oauth2.Token, error) {
+	hc := oauth2.NewClient(i.ctx, i.ts)
+	reqBody := generateAccessTokenReq{
+		Delegates: i.delegates,
+		Lifetime:  i.lifetime,
+		Scope:     i.scopes,
+	}
+	b, err := json.Marshal(reqBody)
+	if err != nil {
+		return nil, fmt.Errorf("impersonate: unable to marshal request: %v", err)
+	}
+	url := fmt.Sprintf("https://iamcredentials.googleapis.com/v1/%s:generateAccessToken", i.name)
+	req, err := http.NewRequest("POST", url, bytes.NewReader(b))
+	if err != nil {
+		return nil, fmt.Errorf("impersonate: unable to create request: %v", err)
+	}
+	req = req.WithContext(i.ctx)
+	req.Header.Set("Content-Type", "application/json")
+
+	resp, err := hc.Do(req)
+	if err != nil {
+		return nil, fmt.Errorf("impersonate: 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("impersonate: unable to read body: %v", err)
+	}
+	if c := resp.StatusCode; c < 200 || c > 299 {
+		return nil, fmt.Errorf("impersonate: status code %d: %s", c, body)
+	}
+
+	var accessTokenResp generateAccessTokenResp
+	if err := json.Unmarshal(body, &accessTokenResp); err != nil {
+		return nil, fmt.Errorf("impersonate: unable to parse response: %v", err)
+	}
+	expiry, err := time.Parse(time.RFC3339, accessTokenResp.ExpireTime)
+	if err != nil {
+		return nil, fmt.Errorf("impersonate: unable to parse expiry: %v", err)
+	}
+	return &oauth2.Token{
+		AccessToken: accessTokenResp.AccessToken,
+		Expiry:      expiry,
+	}, nil
+}