oauth2/google: add config type to use Cloud SDK credentials

Change-Id: Ied7fecc0cb155c33faca7766b81221eacb3aa0c0
Reviewed-on: https://go-review.googlesource.com/1670
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Burcu Dogan <jbd@google.com>

google/example_test.go

@@ -74,6 +74,19 @@ func ExampleJWTConfigFromJSON() {
 	client.Get("...")
 }
 
+func ExampleSDKConfig() {
+	// The credentials will be obtained from the first account that
+	// has been authorized with `gcloud auth login`.
+	conf, err := google.NewSDKConfig("")
+	if err != nil {
+		log.Fatal(err)
+	}
+	// Initiate an http.Client. The following GET request will be
+	// authorized and authenticated on the behalf of the SDK user.
+	client := conf.Client(oauth2.NoContext)
+	client.Get("...")
+}
+
 func Example_serviceAccount() {
 	// Your credentials should be obtained from the Google
 	// Developer Console (https://console.developers.google.com).

google/sdk.go

@@ -0,0 +1,162 @@
+// Copyright 2015 The oauth2 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 google
+
+import (
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"os"
+	"os/user"
+	"path/filepath"
+	"runtime"
+	"strings"
+	"time"
+
+	"golang.org/x/oauth2"
+	"golang.org/x/oauth2/internal"
+)
+
+type sdkCredentials struct {
+	Data []struct {
+		Credential struct {
+			ClientID     string    `json:"client_id"`
+			ClientSecret string    `json:"client_secret"`
+			AccessToken  string    `json:"access_token"`
+			RefreshToken string    `json:"refresh_token"`
+			TokenExpiry  time.Time `json:"token_expiry"`
+		} `json:"credential"`
+		Key struct {
+			Account string `json:"account"`
+			Scope   string `json:"scope"`
+		} `json:"key"`
+	}
+}
+
+// An SDKConfig provides access to tokens from an account already
+// authorized via the Google Cloud SDK.
+type SDKConfig struct {
+	conf         oauth2.Config
+	initialToken *oauth2.Token
+}
+
+// NewSDKConfig creates an SDKConfig for the given Google Cloud SDK
+// account. If account is empty, the account currently active in
+// Google Cloud SDK properties is used.
+// Google Cloud SDK credentials must be created by running `gcloud auth`
+// before using this function.
+// The Google Cloud SDK is available at https://cloud.google.com/sdk/.
+func NewSDKConfig(account string) (*SDKConfig, error) {
+	configPath, err := sdkConfigPath()
+	if err != nil {
+		return nil, fmt.Errorf("oauth2/google: error getting SDK config path: %v", err)
+	}
+	credentialsPath := filepath.Join(configPath, "credentials")
+	f, err := os.Open(credentialsPath)
+	if err != nil {
+		return nil, fmt.Errorf("oauth2/google: failed to load SDK credentials: %v", err)
+	}
+	defer f.Close()
+
+	var c sdkCredentials
+	if err := json.NewDecoder(f).Decode(&c); err != nil {
+		return nil, fmt.Errorf("oauth2/google: failed to decode SDK credentials from %q: %v", credentialsPath, err)
+	}
+	if len(c.Data) == 0 {
+		return nil, fmt.Errorf("oauth2/google: no credentials found in %q, run `gcloud auth login` to create one", credentialsPath)
+	}
+	if account == "" {
+		propertiesPath := filepath.Join(configPath, "properties")
+		f, err := os.Open(propertiesPath)
+		if err != nil {
+			return nil, fmt.Errorf("oauth2/google: failed to load SDK properties: %v", err)
+		}
+		defer f.Close()
+		ini, err := internal.ParseINI(f)
+		if err != nil {
+			return nil, fmt.Errorf("oauth2/google: failed to parse SDK properties %q: %v", propertiesPath, err)
+		}
+		core, ok := ini["core"]
+		if !ok {
+			return nil, fmt.Errorf("oauth2/google: failed to find [core] section in %v", ini)
+		}
+		active, ok := core["account"]
+		if !ok {
+			return nil, fmt.Errorf("oauth2/google: failed to find %q attribute in %v", "account", core)
+		}
+		account = active
+	}
+
+	for _, d := range c.Data {
+		if account == "" || d.Key.Account == account {
+			return &SDKConfig{
+				conf: oauth2.Config{
+					ClientID:     d.Credential.ClientID,
+					ClientSecret: d.Credential.ClientSecret,
+					Scopes:       strings.Split(d.Key.Scope, " "),
+					Endpoint:     Endpoint,
+					RedirectURL:  "oob",
+				},
+				initialToken: &oauth2.Token{
+					AccessToken:  d.Credential.AccessToken,
+					RefreshToken: d.Credential.RefreshToken,
+					Expiry:       d.Credential.TokenExpiry,
+				},
+			}, nil
+		}
+	}
+	return nil, fmt.Errorf("oauth2/google: no such credentials for account %q", account)
+}
+
+// Client returns an HTTP client using Google Cloud SDK credentials to
+// authorize requests. The token will auto-refresh as necessary. The
+// underlying http.RoundTripper will be obtained using the provided
+// context. The returned client and its Transport should not be
+// modified.
+func (c *SDKConfig) Client(ctx oauth2.Context) *http.Client {
+	return &http.Client{
+		Transport: &oauth2.Transport{
+			Source: c.TokenSource(ctx),
+		},
+	}
+}
+
+// TokenSource returns an oauth2.TokenSource that retrieve tokens from
+// Google Cloud SDK credentials using the provided context.
+// It will returns the current access token stored in the credentials,
+// and refresh it when it expires, but it won't update the credentials
+// with the new access token.
+func (c *SDKConfig) TokenSource(ctx oauth2.Context) oauth2.TokenSource {
+	return c.conf.TokenSource(ctx, c.initialToken)
+}
+
+// Scopes are the OAuth 2.0 scopes the current account is authorized for.
+func (c *SDKConfig) Scopes() []string {
+	return c.conf.Scopes
+}
+
+func sdkConfigPath() (string, error) {
+	if runtime.GOOS == "windows" {
+		return filepath.Join(os.Getenv("APPDATA"), "gcloud"), nil
+	}
+	unixHomeDir = guessUnixHomeDir()
+	if unixHomeDir == "" {
+		return "", fmt.Errorf("unable to get current user home directory: os/user lookup failed; $HOME is empty")
+	}
+	return filepath.Join(unixHomeDir, ".config", "gcloud"), nil
+}
+
+var unixHomeDir string
+
+func guessUnixHomeDir() string {
+	if unixHomeDir != "" {
+		return unixHomeDir
+	}
+	usr, err := user.Current()
+	if err == nil {
+		return usr.HomeDir
+	}
+	return os.Getenv("HOME")
+}

google/sdk_test.go

@@ -0,0 +1,39 @@
+// Copyright 2015 The oauth2 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 google
+
+import "testing"
+
+func TestSDKConfig(t *testing.T) {
+	unixHomeDir = "testdata"
+	tests := []struct {
+		account     string
+		accessToken string
+		err         bool
+	}{
+		{"", "bar_access_token", false},
+		{"foo@example.com", "foo_access_token", false},
+		{"bar@example.com", "bar_access_token", false},
+	}
+	for _, tt := range tests {
+		c, err := NewSDKConfig(tt.account)
+		if (err != nil) != tt.err {
+			if !tt.err {
+				t.Errorf("expected no error, got error: %v", tt.err, err)
+			} else {
+				t.Errorf("execcted error, got none")
+			}
+			continue
+		}
+		tok := c.initialToken
+		if tok == nil {
+			t.Errorf("expected token %q, got: nil", tt.accessToken)
+			continue
+		}
+		if tok.AccessToken != tt.accessToken {
+			t.Errorf("expected token %q, got: %q", tt.accessToken, tok.AccessToken)
+		}
+	}
+}

google/testdata/.config/gcloud/credentials

@@ -0,0 +1,89 @@
+{
+  "data": [
+    {
+      "credential": {
+        "_class": "OAuth2Credentials",
+        "_module": "oauth2client.client",
+        "access_token": "foo_access_token",
+        "client_id": "foo_client_id",
+        "client_secret": "foo_client_secret",
+        "id_token": {
+          "at_hash": "foo_at_hash",
+          "aud": "foo_aud",
+          "azp": "foo_azp",
+          "cid": "foo_cid",
+          "email": "foo@example.com",
+          "email_verified": true,
+          "exp": 1420573614,
+          "iat": 1420569714,
+          "id": "1337",
+          "iss": "accounts.google.com",
+          "sub": "1337",
+          "token_hash": "foo_token_hash",
+          "verified_email": true
+        },
+        "invalid": false,
+        "refresh_token": "foo_refresh_token",
+        "revoke_uri": "https://accounts.google.com/o/oauth2/revoke",
+        "token_expiry": "2015-01-09T00:51:51Z",
+        "token_response": {
+          "access_token": "foo_access_token",
+          "expires_in": 3600,
+          "id_token": "foo_id_token",
+          "token_type": "Bearer"
+        },
+        "token_uri": "https://accounts.google.com/o/oauth2/token",
+        "user_agent": "Cloud SDK Command Line Tool"
+      },
+      "key": {
+        "account": "foo@example.com",
+        "clientId": "foo_client_id",
+        "scope": "https://www.googleapis.com/auth/appengine.admin https://www.googleapis.com/auth/bigquery https://www.googleapis.com/auth/compute https://www.googleapis.com/auth/devstorage.full_control https://www.googleapis.com/auth/userinfo.email https://www.googleapis.com/auth/ndev.cloudman https://www.googleapis.com/auth/cloud-platform https://www.googleapis.com/auth/sqlservice.admin https://www.googleapis.com/auth/prediction https://www.googleapis.com/auth/projecthosting",
+        "type": "google-cloud-sdk"
+      }
+    },
+    {
+      "credential": {
+        "_class": "OAuth2Credentials",
+        "_module": "oauth2client.client",
+        "access_token": "bar_access_token",
+        "client_id": "bar_client_id",
+        "client_secret": "bar_client_secret",
+        "id_token": {
+          "at_hash": "bar_at_hash",
+          "aud": "bar_aud",
+          "azp": "bar_azp",
+          "cid": "bar_cid",
+          "email": "bar@example.com",
+          "email_verified": true,
+          "exp": 1420573614,
+          "iat": 1420569714,
+          "id": "1337",
+          "iss": "accounts.google.com",
+          "sub": "1337",
+          "token_hash": "bar_token_hash",
+          "verified_email": true
+        },
+        "invalid": false,
+        "refresh_token": "bar_refresh_token",
+        "revoke_uri": "https://accounts.google.com/o/oauth2/revoke",
+        "token_expiry": "2015-01-09T00:51:51Z",
+        "token_response": {
+          "access_token": "bar_access_token",
+          "expires_in": 3600,
+          "id_token": "bar_id_token",
+          "token_type": "Bearer"
+        },
+        "token_uri": "https://accounts.google.com/o/oauth2/token",
+        "user_agent": "Cloud SDK Command Line Tool"
+      },
+      "key": {
+        "account": "bar@example.com",
+        "clientId": "bar_client_id",
+        "scope": "https://www.googleapis.com/auth/appengine.admin https://www.googleapis.com/auth/bigquery https://www.googleapis.com/auth/compute https://www.googleapis.com/auth/devstorage.full_control https://www.googleapis.com/auth/userinfo.email https://www.googleapis.com/auth/ndev.cloudman https://www.googleapis.com/auth/cloud-platform https://www.googleapis.com/auth/sqlservice.admin https://www.googleapis.com/auth/prediction https://www.googleapis.com/auth/projecthosting",
+        "type": "google-cloud-sdk"
+      }
+    }
+  ],
+  "file_version": 1
+}

google/testdata/.config/gcloud/properties

@@ -0,0 +1,2 @@
+[core]
+account = bar@example.com

internal/oauth2.go

@@ -6,10 +6,14 @@
 package internal
 
 import (
+	"bufio"
 	"crypto/rsa"
 	"crypto/x509"
 	"encoding/pem"
 	"errors"
+	"fmt"
+	"io"
+	"strings"
 )
 
 // ParseKey converts the binary contents of a private key file
@@ -35,3 +39,31 @@ func ParseKey(key []byte) (*rsa.PrivateKey, error) {
 	}
 	return parsed, nil
 }
+
+func ParseINI(ini io.Reader) (map[string]map[string]string, error) {
+	result := map[string]map[string]string{
+		"": map[string]string{}, // root section
+	}
+	scanner := bufio.NewScanner(ini)
+	currentSection := ""
+	for scanner.Scan() {
+		line := strings.TrimSpace(scanner.Text())
+		if strings.HasPrefix(line, ";") {
+			// comment.
+			continue
+		}
+		if strings.HasPrefix(line, "[") && strings.HasSuffix(line, "]") {
+			currentSection = strings.TrimSpace(line[1 : len(line)-1])
+			result[currentSection] = map[string]string{}
+			continue
+		}
+		parts := strings.SplitN(line, "=", 2)
+		if len(parts) == 2 && parts[0] != "" {
+			result[currentSection][strings.TrimSpace(parts[0])] = strings.TrimSpace(parts[1])
+		}
+	}
+	if err := scanner.Err(); err != nil {
+		return nil, fmt.Errorf("error scanning ini: %v", err)
+	}
+	return result, nil
+}

internal/oauth2_test.go

@@ -0,0 +1,62 @@
+// Copyright 2014 The oauth2 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 internal contains support packages for oauth2 package.
+package internal
+
+import (
+	"reflect"
+	"strings"
+	"testing"
+)
+
+func TestParseINI(t *testing.T) {
+	tests := []struct {
+		ini  string
+		want map[string]map[string]string
+	}{
+		{
+			`root = toor
+[foo]  
+bar = hop
+ini = nin
+`,
+			map[string]map[string]string{
+				"":    map[string]string{"root": "toor"},
+				"foo": map[string]string{"bar": "hop", "ini": "nin"},
+			},
+		},
+		{
+			`[empty]
+[section]
+empty=
+`,
+			map[string]map[string]string{
+				"":        map[string]string{},
+				"empty":   map[string]string{},
+				"section": map[string]string{"empty": ""},
+			},
+		},
+		{
+			`ignore
+[invalid
+=stuff
+;comment=true
+`,
+			map[string]map[string]string{
+				"a": map[string]string{},
+			},
+		},
+	}
+	for _, tt := range tests {
+		result, err := ParseINI(strings.NewReader(tt.ini))
+		if err != nil {
+			t.Errorf("ParseINI(%q) error %v, want: no error", tt.ini, err)
+			continue
+		}
+		if !reflect.DeepEqual(result, tt.want) {
+			t.Errorf("ParseINI(%q) = %#v, want: %#v", tt.ini, result, tt.want)
+		}
+	}
+}