Add simple Google provider

Adds a simple Google provider. Closes #214

Adds a new "Google" provider. This essentially clones the existing
`gplus` provider, with a few differences:

  * It will, by default, only send the `email` scope, since
  `profile` is a Google+ specific scope, and `openid` is a bit
  excessive for a default scope.
  * It uses the `oauth2.Endpoint` from `golang.org/x/oauth2/google`
  so we always keep up to date with Go's OAuth2 package.
  * It simplifies the logic that populates a `goth.User` from the JSON
  returned from Google's server.

It also includes a few housekeeping items:

  1. Marks the Google+ provider as deprecated in the README.
  2. Updates the `go.mod` file.
  3. Checks in the `go.sum` file. I know not everyone does this, but for
  now it seems to be community consensus that it's a good idea to check
  it in, so I figure we'd do that.

README.md

@@ -33,7 +33,8 @@ $ go get github.com/markbates/goth
 * Fitbit
 * GitHub
 * Gitlab
-* Google+
+* Google
+* Google+ (deprecated)
 * Heroku
 * InfluxCloud
 * Instagram

examples/main.go

@@ -29,6 +29,7 @@ import (
 	"github.com/markbates/goth/providers/fitbit"
 	"github.com/markbates/goth/providers/github"
 	"github.com/markbates/goth/providers/gitlab"
+	"github.com/markbates/goth/providers/google"
 	"github.com/markbates/goth/providers/gplus"
 	"github.com/markbates/goth/providers/heroku"
 	"github.com/markbates/goth/providers/instagram"
@@ -65,6 +66,7 @@ func main() {
 
 		facebook.New(os.Getenv("FACEBOOK_KEY"), os.Getenv("FACEBOOK_SECRET"), "http://localhost:3000/auth/facebook/callback"),
 		fitbit.New(os.Getenv("FITBIT_KEY"), os.Getenv("FITBIT_SECRET"), "http://localhost:3000/auth/fitbit/callback"),
+		google.New(os.Getenv("GOOGLE_KEY"), os.Getenv("GOOGLE_SECRET"), "http://localhost:3000/auth/google/callback"),
 		gplus.New(os.Getenv("GPLUS_KEY"), os.Getenv("GPLUS_SECRET"), "http://localhost:3000/auth/gplus/callback"),
 		github.New(os.Getenv("GITHUB_KEY"), os.Getenv("GITHUB_SECRET"), "http://localhost:3000/auth/github/callback"),
 		spotify.New(os.Getenv("SPOTIFY_KEY"), os.Getenv("SPOTIFY_SECRET"), "http://localhost:3000/auth/spotify/callback"),
@@ -134,6 +136,8 @@ func main() {
 	m["fitbit"] = "Fitbit"
 	m["github"] = "Github"
 	m["gitlab"] = "Gitlab"
+	m["google"] = "Google"
+	m["gplus"] = "Google Plus"
 	m["soundcloud"] = "SoundCloud"
 	m["spotify"] = "Spotify"
 	m["steam"] = "Steam"
@@ -143,7 +147,6 @@ func main() {
 	m["wepay"] = "Wepay"
 	m["yahoo"] = "Yahoo"
 	m["yammer"] = "Yammer"
-	m["gplus"] = "Google Plus"
 	m["heroku"] = "Heroku"
 	m["instagram"] = "Instagram"
 	m["intercom"] = "Intercom"

go.mod

@@ -1,6 +1,7 @@
 module github.com/markbates/goth
 
 require (
+	cloud.google.com/go v0.30.0
 	github.com/gorilla/mux v1.6.2
 	github.com/gorilla/pat v0.0.0-20180118222023-199c85a7f6d1
 	github.com/gorilla/sessions v1.1.1

go.sum

@@ -0,0 +1,22 @@
+cloud.google.com/go v0.30.0 h1:xKvyLgk56d0nksWq49J0UyGEeUIicTl4+UBiX1NPX9g=
+cloud.google.com/go v0.30.0/go.mod h1:aQUYkXzVsufM+DwF1aE+0xfcU+56JwCaLick0ClmMTw=
+cloud.google.com/go/compute v0.0.0-20181010175407-5f0ffe772937/go.mod h1:G7mAYYxgmS0lVkHyy2hEOLQCFB0DlQFTMLWggykrydY=
+cloud.google.com/go/compute/metadata v0.0.0-20181010175407-5f0ffe772937/go.mod h1:G7mAYYxgmS0lVkHyy2hEOLQCFB0DlQFTMLWggykrydY=
+github.com/gorilla/context v1.1.1 h1:AWwleXJkX/nhcU9bZSnZoi3h/qGYqQAGhq6zZe/aQW8=
+github.com/gorilla/context v1.1.1/go.mod h1:kBGZzfjB9CEq2AlWe17Uuf7NDRt0dE0s8S51q0aT7Yg=
+github.com/gorilla/mux v1.6.2 h1:Pgr17XVTNXAk3q/r4CpKzC5xBM/qW1uVLV+IhRZpIIk=
+github.com/gorilla/mux v1.6.2/go.mod h1:1lud6UwP+6orDFRuTfBEV8e9/aOM/c4fVVCaMa2zaAs=
+github.com/gorilla/pat v0.0.0-20180118222023-199c85a7f6d1 h1:LqbZZ9sNMWVjeXS4NN5oVvhMjDyLhmA1LG86oSo+IqY=
+github.com/gorilla/pat v0.0.0-20180118222023-199c85a7f6d1/go.mod h1:YeAe0gNeiNT5hoiZRI4yiOky6jVdNvfO2N6Kav/HmxY=
+github.com/gorilla/securecookie v1.1.1 h1:miw7JPhV+b/lAHSXz4qd/nN9jRiAFV5FwjeKyCS8BvQ=
+github.com/gorilla/securecookie v1.1.1/go.mod h1:ra0sb63/xPlUeL+yeDciTfxMRAA+MP+HVt/4epWDjd4=
+github.com/gorilla/sessions v1.1.1 h1:YMDmfaK68mUixINzY/XjscuJ47uXFWSSHzFbBQM0PrE=
+github.com/gorilla/sessions v1.1.1/go.mod h1:8KCfur6+4Mqcc6S0FEfKuN15Vl5MgXW92AE8ovaJD0w=
+github.com/markbates/going v1.0.0 h1:DQw0ZP7NbNlFGcKbcE/IVSOAFzScxRtLpd0rLMzLhq0=
+github.com/markbates/going v1.0.0/go.mod h1:I6mnB4BPnEeqo85ynXIx1ZFLLbtiLHNXVgWeFO9OGOA=
+github.com/mrjones/oauth v0.0.0-20180629183705-f4e24b6d100c h1:3wkDRdxK92dF+c1ke2dtj7ZzemFWBHB9plnJOtlwdFA=
+github.com/mrjones/oauth v0.0.0-20180629183705-f4e24b6d100c/go.mod h1:skjdDftzkFALcuGzYSklqYd8gvat6F1gZJ4YPVbkZpM=
+golang.org/x/net v0.0.0-20180706051357-32a936f46389 h1:U+zCn5sqaq+q4hrnMrz9sgrW1yatwEOUgYkGt3u9ZOU=
+golang.org/x/net v0.0.0-20180706051357-32a936f46389/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
+golang.org/x/oauth2 v0.0.0-20180620175406-ef147856a6dd h1:QQhib242ErYDSMitlBm8V7wYCm/1a25hV8qMadIKLPA=
+golang.org/x/oauth2 v0.0.0-20180620175406-ef147856a6dd/go.mod h1:N/0e6XlmueqKjAGxoOufVs8QHGRruUQn6yWY3a++T0U=

providers/google/google.go

@@ -0,0 +1,171 @@
+// Package google implements the OAuth2 protocol for authenticating users
+// through Google.
+package google
+
+import (
+	"encoding/json"
+	"net/http"
+	"net/url"
+	"strings"
+
+	"fmt"
+
+	"github.com/markbates/goth"
+	"golang.org/x/oauth2"
+	goog "golang.org/x/oauth2/google"
+)
+
+const endpointProfile string = "https://www.googleapis.com/oauth2/v2/userinfo"
+
+// New creates a new Google+ provider, and sets up important connection details.
+// You should always call `google.New` to get a new Provider. Never try to create
+// one manually.
+func New(clientKey, secret, callbackURL string, scopes ...string) *Provider {
+	p := &Provider{
+		ClientKey:    clientKey,
+		Secret:       secret,
+		CallbackURL:  callbackURL,
+		providerName: "google",
+	}
+	p.config = newConfig(p, scopes)
+	return p
+}
+
+// Provider is the implementation of `goth.Provider` for accessing Google+.
+type Provider struct {
+	ClientKey    string
+	Secret       string
+	CallbackURL  string
+	HTTPClient   *http.Client
+	config       *oauth2.Config
+	prompt       oauth2.AuthCodeOption
+	providerName string
+}
+
+// Name is the name used to retrieve this provider later.
+func (p *Provider) Name() string {
+	return p.providerName
+}
+
+// SetName is to update the name of the provider (needed in case of multiple providers of 1 type)
+func (p *Provider) SetName(name string) {
+	p.providerName = name
+}
+
+// Client returns an HTTP client to be used in all fetch operations.
+func (p *Provider) Client() *http.Client {
+	return goth.HTTPClientWithFallBack(p.HTTPClient)
+}
+
+// Debug is a no-op for the google package.
+func (p *Provider) Debug(debug bool) {}
+
+// BeginAuth asks Google for an authentication endpoint.
+func (p *Provider) BeginAuth(state string) (goth.Session, error) {
+	var opts []oauth2.AuthCodeOption
+	if p.prompt != nil {
+		opts = append(opts, p.prompt)
+	}
+	url := p.config.AuthCodeURL(state, opts...)
+	session := &Session{
+		AuthURL: url,
+	}
+	return session, nil
+}
+
+type googleUser struct {
+	ID        string `json:"id"`
+	Email     string `json:"email"`
+	Name      string `json:"name"`
+	FirstName string `json:"given_name"`
+	LastName  string `json:"family_name"`
+	Link      string `json:"link"`
+	Picture   string `json:"picture"`
+}
+
+// FetchUser will go to Google and access basic information about the user.
+func (p *Provider) FetchUser(session goth.Session) (goth.User, error) {
+	sess := session.(*Session)
+	user := goth.User{
+		AccessToken:  sess.AccessToken,
+		Provider:     p.Name(),
+		RefreshToken: sess.RefreshToken,
+		ExpiresAt:    sess.ExpiresAt,
+	}
+
+	if user.AccessToken == "" {
+		// Data is not yet retrieved, since accessToken is still empty.
+		return user, fmt.Errorf("%s cannot get user information without accessToken", p.providerName)
+	}
+
+	response, err := p.Client().Get(endpointProfile + "?access_token=" + url.QueryEscape(sess.AccessToken))
+	if err != nil {
+		return user, err
+	}
+	if response.StatusCode != http.StatusOK {
+		return user, fmt.Errorf("%s responded with a %d trying to fetch user information", p.providerName, response.StatusCode)
+	}
+
+	u := &googleUser{}
+	if err := json.NewDecoder(response.Body).Decode(u); err != nil {
+		return user, err
+	}
+	defer response.Body.Close()
+
+	// Extract the user data we got from Google into our goth.User.
+	user.Name = u.Name
+	user.FirstName = u.FirstName
+	user.LastName = u.LastName
+	user.NickName = u.Name
+	user.Email = u.Email
+	user.AvatarURL = u.Picture
+	user.UserID = u.ID
+
+	return user, nil
+}
+
+func newConfig(provider *Provider, scopes []string) *oauth2.Config {
+	c := &oauth2.Config{
+		ClientID:     provider.ClientKey,
+		ClientSecret: provider.Secret,
+		RedirectURL:  provider.CallbackURL,
+		Endpoint:     goog.Endpoint,
+		Scopes:       []string{},
+	}
+
+	if len(scopes) > 0 {
+		for _, scope := range scopes {
+			c.Scopes = append(c.Scopes, scope)
+		}
+	} else {
+		c.Scopes = []string{"email"}
+	}
+	return c
+}
+
+//RefreshTokenAvailable refresh token is provided by auth provider or not
+func (p *Provider) RefreshTokenAvailable() bool {
+	return true
+}
+
+//RefreshToken get new access token based on the refresh token
+func (p *Provider) RefreshToken(refreshToken string) (*oauth2.Token, error) {
+	token := &oauth2.Token{RefreshToken: refreshToken}
+	ts := p.config.TokenSource(goth.ContextForClient(p.Client()), token)
+	newToken, err := ts.Token()
+	if err != nil {
+		return nil, err
+	}
+	return newToken, err
+}
+
+// SetPrompt sets the prompt values for the google OAuth call. Use this to
+// force users to choose and account every time by passing "select_account",
+// for example.
+// See https://developers.google.com/identity/protocols/OpenIDConnect#authenticationuriparameters
+func (p *Provider) SetPrompt(prompt ...string) {
+	if len(prompt) == 0 {
+		return
+	}
+	p.prompt = oauth2.SetAuthURLParam("prompt", strings.Join(prompt, " "))
+}

providers/google/google_test.go

@@ -0,0 +1,78 @@
+package google_test
+
+import (
+	"fmt"
+	"os"
+	"testing"
+
+	"github.com/markbates/goth"
+	"github.com/markbates/goth/providers/google"
+	"github.com/stretchr/testify/assert"
+)
+
+func Test_New(t *testing.T) {
+	t.Parallel()
+	a := assert.New(t)
+
+	provider := googleProvider()
+	a.Equal(provider.ClientKey, os.Getenv("GOOGLE_KEY"))
+	a.Equal(provider.Secret, os.Getenv("GOOGLE_SECRET"))
+	a.Equal(provider.CallbackURL, "/foo")
+}
+
+func Test_BeginAuth(t *testing.T) {
+	t.Parallel()
+	a := assert.New(t)
+
+	provider := googleProvider()
+	session, err := provider.BeginAuth("test_state")
+	s := session.(*google.Session)
+	a.NoError(err)
+	a.Contains(s.AuthURL, "accounts.google.com/o/oauth2/auth")
+	a.Contains(s.AuthURL, fmt.Sprintf("client_id=%s", os.Getenv("GOOGLE_KEY")))
+	a.Contains(s.AuthURL, "state=test_state")
+	a.Contains(s.AuthURL, "scope=email")
+}
+
+func Test_BeginAuthWithPrompt(t *testing.T) {
+	// This exists because there was a panic caused by the oauth2 package when
+	// the AuthCodeOption passed was nil. This test uses it, Test_BeginAuth does
+	// not, to ensure both cases are covered.
+	t.Parallel()
+	a := assert.New(t)
+
+	provider := googleProvider()
+	provider.SetPrompt("test", "prompts")
+	session, err := provider.BeginAuth("test_state")
+	s := session.(*google.Session)
+	a.NoError(err)
+	a.Contains(s.AuthURL, "accounts.google.com/o/oauth2/auth")
+	a.Contains(s.AuthURL, fmt.Sprintf("client_id=%s", os.Getenv("GOOGLE_KEY")))
+	a.Contains(s.AuthURL, "state=test_state")
+	a.Contains(s.AuthURL, "scope=email")
+	a.Contains(s.AuthURL, "prompt=test+prompts")
+}
+
+func Test_Implements_Provider(t *testing.T) {
+	t.Parallel()
+	a := assert.New(t)
+
+	a.Implements((*goth.Provider)(nil), googleProvider())
+}
+
+func Test_SessionFromJSON(t *testing.T) {
+	t.Parallel()
+	a := assert.New(t)
+
+	provider := googleProvider()
+
+	s, err := provider.UnmarshalSession(`{"AuthURL":"https://accounts.google.com/o/oauth2/auth","AccessToken":"1234567890"}`)
+	a.NoError(err)
+	session := s.(*google.Session)
+	a.Equal(session.AuthURL, "https://accounts.google.com/o/oauth2/auth")
+	a.Equal(session.AccessToken, "1234567890")
+}
+
+func googleProvider() *google.Provider {
+	return google.New(os.Getenv("GOOGLE_KEY"), os.Getenv("GOOGEL_SECRET"), "/foo")
+}

providers/google/session.go

@@ -0,0 +1,61 @@
+package google
+
+import (
+	"encoding/json"
+	"errors"
+	"strings"
+	"time"
+
+	"github.com/markbates/goth"
+)
+
+// Session stores data during the auth process with Google+.
+type Session struct {
+	AuthURL      string
+	AccessToken  string
+	RefreshToken string
+	ExpiresAt    time.Time
+}
+
+// GetAuthURL will return the URL set by calling the `BeginAuth` function on the Google+ provider.
+func (s Session) GetAuthURL() (string, error) {
+	if s.AuthURL == "" {
+		return "", errors.New(goth.NoAuthUrlErrorMessage)
+	}
+	return s.AuthURL, nil
+}
+
+// Authorize the session with Google+ and return the access token to be stored for future use.
+func (s *Session) Authorize(provider goth.Provider, params goth.Params) (string, error) {
+	p := provider.(*Provider)
+	token, err := p.config.Exchange(goth.ContextForClient(p.Client()), params.Get("code"))
+	if err != nil {
+		return "", err
+	}
+
+	if !token.Valid() {
+		return "", errors.New("Invalid token received from provider")
+	}
+
+	s.AccessToken = token.AccessToken
+	s.RefreshToken = token.RefreshToken
+	s.ExpiresAt = token.Expiry
+	return token.AccessToken, err
+}
+
+// Marshal the session into a string
+func (s Session) Marshal() string {
+	b, _ := json.Marshal(s)
+	return string(b)
+}
+
+func (s Session) String() string {
+	return s.Marshal()
+}
+
+// UnmarshalSession will unmarshal a JSON string into a session.
+func (p *Provider) UnmarshalSession(data string) (goth.Session, error) {
+	sess := &Session{}
+	err := json.NewDecoder(strings.NewReader(data)).Decode(sess)
+	return sess, err
+}