Add GoogleIdProvider.

idp/google.go

@@ -0,0 +1,66 @@
+// Copyright 2021 The casbin Authors. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package idp
+
+import (
+	"encoding/json"
+	"errors"
+	"io/ioutil"
+	"net/http"
+
+	"golang.org/x/oauth2"
+)
+
+type GoogleIdProvider struct{}
+
+func (idp *GoogleIdProvider) GetConfig() *oauth2.Config {
+	var endpoint = oauth2.Endpoint{
+		AuthURL:  "https://accounts.google.com/o/oauth2/auth",
+		TokenURL: "https://accounts.google.com/o/oauth2/token",
+	}
+
+	var config = &oauth2.Config{
+		Scopes:   []string{"profile", "email"},
+		Endpoint: endpoint,
+	}
+
+	return config
+}
+
+func (idp *GoogleIdProvider) GetUserInfo(httpClient *http.Client, token *oauth2.Token) (string, string, string, error) {
+	var email, username, avatarUrl string
+
+	type userInfoFromGoogle struct {
+		Picture string `json:"picture"`
+		Email   string `json:"email"`
+	}
+
+	resp, err := httpClient.Get("https://www.googleapis.com/oauth2/v2/userinfo?alt=json&access_token=" + token.AccessToken)
+	defer resp.Body.Close()
+	contents, err := ioutil.ReadAll(resp.Body)
+	var tempUser userInfoFromGoogle
+	err = json.Unmarshal(contents, &tempUser)
+	if err != nil {
+		panic(err)
+	}
+	email = tempUser.Email
+	avatarUrl = tempUser.Picture
+
+	if email == "" {
+		return email, username, avatarUrl, errors.New("google email is empty, please try again")
+	}
+
+	return email, username, avatarUrl, nil
+}