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				|  |  | +// Copyright 2014 Google Inc. All Rights Reserved.
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				|  |  | +//
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				|  |  | +// Licensed under the Apache License, Version 2.0 (the "License");
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				|  |  | +// you may not use this file except in compliance with the License.
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				|  |  | +// You may obtain a copy of the License at
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				|  |  | +//
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				|  |  | +//      http://www.apache.org/licenses/LICENSE-2.0
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				|  |  | +//
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				|  |  | +// Unless required by applicable law or agreed to in writing, software
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				|  |  | +// distributed under the License is distributed on an "AS IS" BASIS,
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				|  |  | +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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				|  |  | +// See the License for the specific language governing permissions and
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				|  |  | +// limitations under the License.
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				|  |  | +
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				|  |  | +// Package oauth2 contains Martini handlers to provide
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				|  |  | +// user login via an OAuth 2.0 backend.
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				|  |  | +package oauth2
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				|  |  | +
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				|  |  | +import (
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				|  |  | +	"encoding/json"
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				|  |  | +	"fmt"
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				|  |  | +	"net/http"
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				|  |  | +	"net/url"
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				|  |  | +	"strings"
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				|  |  | +	"time"
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				|  |  | +
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				|  |  | +	"code.google.com/p/goauth2/oauth"
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				|  |  | +	"github.com/go-martini/martini"
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				|  |  | +	"github.com/martini-contrib/sessions"
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				|  |  | +)
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				|  |  | +
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				|  |  | +const (
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				|  |  | +	codeRedirect = 302
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				|  |  | +	keyToken     = "oauth2_token"
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				|  |  | +	keyNextPage  = "next"
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				|  |  | +)
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				|  |  | +
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				|  |  | +var (
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				|  |  | +	// Path to handle OAuth 2.0 logins.
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				|  |  | +	PathLogin = "/login"
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				|  |  | +	// Path to handle OAuth 2.0 logouts.
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				|  |  | +	PathLogout = "/logout"
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				|  |  | +	// Path to handle callback from OAuth 2.0 backend
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				|  |  | +	// to exchange credentials.
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				|  |  | +	PathCallback = "/oauth2callback"
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				|  |  | +	// Path to handle error cases.
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				|  |  | +	PathError = "/oauth2error"
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				|  |  | +)
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				|  |  | +
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				|  |  | +// Represents OAuth2 backend options.
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				|  |  | +type Options struct {
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				|  |  | +	ClientId     string
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				|  |  | +	ClientSecret string
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				|  |  | +	RedirectURL  string
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				|  |  | +	Scopes       []string
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				|  |  | +
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				|  |  | +	AuthUrl  string
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				|  |  | +	TokenUrl string
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				|  |  | +}
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				|  |  | +
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				|  |  | +// Represents a container that contains
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				|  |  | +// user's OAuth 2.0 access and refresh tokens.
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				|  |  | +type Tokens interface {
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				|  |  | +	Access() string
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				|  |  | +	Refresh() string
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				|  |  | +	IsExpired() bool
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				|  |  | +	ExpiryTime() time.Time
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				|  |  | +	ExtraData() map[string]string
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				|  |  | +}
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				|  |  | +
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				|  |  | +type token struct {
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				|  |  | +	oauth.Token
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				|  |  | +}
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				|  |  | +
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				|  |  | +func (t *token) ExtraData() map[string]string {
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				|  |  | +	return t.Extra
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				|  |  | +}
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				|  |  | +
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				|  |  | +// Returns the access token.
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				|  |  | +func (t *token) Access() string {
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				|  |  | +	return t.AccessToken
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				|  |  | +}
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				|  |  | +
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				|  |  | +// Returns the refresh token.
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				|  |  | +func (t *token) Refresh() string {
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				|  |  | +	return t.RefreshToken
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				|  |  | +}
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				|  |  | +
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				|  |  | +// Returns whether the access token is
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				|  |  | +// expired or not.
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				|  |  | +func (t *token) IsExpired() bool {
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				|  |  | +	if t == nil {
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				|  |  | +		return true
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				|  |  | +	}
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				|  |  | +	return t.Expired()
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				|  |  | +}
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				|  |  | +
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				|  |  | +// Returns the expiry time of the user's
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				|  |  | +// access token.
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				|  |  | +func (t *token) ExpiryTime() time.Time {
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				|  |  | +	return t.Expiry
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				|  |  | +}
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				|  |  | +
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				|  |  | +// Formats tokens into string.
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				|  |  | +func (t *token) String() string {
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				|  |  | +	return fmt.Sprintf("tokens: %v", t)
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				|  |  | +}
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				|  |  | +
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				|  |  | +// Returns a new Google OAuth 2.0 backend endpoint.
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				|  |  | +func Google(opts *Options) martini.Handler {
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				|  |  | +	opts.AuthUrl = "https://accounts.google.com/o/oauth2/auth"
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				|  |  | +	opts.TokenUrl = "https://accounts.google.com/o/oauth2/token"
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				|  |  | +	return NewOAuth2Provider(opts)
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				|  |  | +}
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				|  |  | +
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				|  |  | +// Returns a new Github OAuth 2.0 backend endpoint.
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				|  |  | +func Github(opts *Options) martini.Handler {
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				|  |  | +	opts.AuthUrl = "https://github.com/login/oauth/authorize"
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				|  |  | +	opts.TokenUrl = "https://github.com/login/oauth/access_token"
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				|  |  | +	return NewOAuth2Provider(opts)
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				|  |  | +}
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				|  |  | +
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				|  |  | +func Facebook(opts *Options) martini.Handler {
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				|  |  | +	opts.AuthUrl = "https://www.facebook.com/dialog/oauth"
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				|  |  | +	opts.TokenUrl = "https://graph.facebook.com/oauth/access_token"
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				|  |  | +	return NewOAuth2Provider(opts)
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				|  |  | +}
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				|  |  | +
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				|  |  | +// Returns a generic OAuth 2.0 backend endpoint.
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				|  |  | +func NewOAuth2Provider(opts *Options) martini.Handler {
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				|  |  | +	config := &oauth.Config{
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				|  |  | +		ClientId:     opts.ClientId,
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				|  |  | +		ClientSecret: opts.ClientSecret,
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				|  |  | +		RedirectURL:  opts.RedirectURL,
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				|  |  | +		Scope:        strings.Join(opts.Scopes, " "),
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				|  |  | +		AuthURL:      opts.AuthUrl,
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				|  |  | +		TokenURL:     opts.TokenUrl,
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				|  |  | +	}
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				|  |  | +
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				|  |  | +	transport := &oauth.Transport{
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				|  |  | +		Config:    config,
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				|  |  | +		Transport: http.DefaultTransport,
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				|  |  | +	}
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				|  |  | +
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				|  |  | +	return func(s sessions.Session, c martini.Context, w http.ResponseWriter, r *http.Request) {
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				|  |  | +		if r.Method == "GET" {
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				|  |  | +			switch r.URL.Path {
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				|  |  | +			case PathLogin:
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				|  |  | +				login(transport, s, w, r)
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				|  |  | +			case PathLogout:
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				|  |  | +				logout(transport, s, w, r)
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				|  |  | +			case PathCallback:
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				|  |  | +				handleOAuth2Callback(transport, s, w, r)
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				|  |  | +			}
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				|  |  | +		}
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				|  |  | +
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				|  |  | +		tk := unmarshallToken(s)
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				|  |  | +		if tk != nil {
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				|  |  | +			// check if the access token is expired
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				|  |  | +			if tk.IsExpired() && tk.Refresh() == "" {
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				|  |  | +				s.Delete(keyToken)
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				|  |  | +				tk = nil
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				|  |  | +			}
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				|  |  | +		}
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				|  |  | +		// Inject tokens.
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				|  |  | +		c.MapTo(tk, (*Tokens)(nil))
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				|  |  | +	}
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				|  |  | +}
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				|  |  | +
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				|  |  | +// Handler that redirects user to the login page
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				|  |  | +// if user is not logged in.
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				|  |  | +// Sample usage:
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				|  |  | +// m.Get("/login-required", oauth2.LoginRequired, func() ... {})
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				|  |  | +var LoginRequired martini.Handler = func() martini.Handler {
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				|  |  | +	return func(s sessions.Session, c martini.Context, w http.ResponseWriter, r *http.Request) {
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				|  |  | +		token := unmarshallToken(s)
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				|  |  | +		if token == nil || token.IsExpired() {
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				|  |  | +			next := url.QueryEscape(r.URL.RequestURI())
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				|  |  | +			http.Redirect(w, r, PathLogin+"?next="+next, codeRedirect)
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				|  |  | +		}
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				|  |  | +	}
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				|  |  | +}()
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				|  |  | +
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				|  |  | +func login(t *oauth.Transport, s sessions.Session, w http.ResponseWriter, r *http.Request) {
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				|  |  | +	next := extractPath(r.URL.Query().Get(keyNextPage))
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				|  |  | +	if s.Get(keyToken) == nil {
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				|  |  | +		// User is not logged in.
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				|  |  | +		http.Redirect(w, r, t.Config.AuthCodeURL(next), codeRedirect)
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				|  |  | +		return
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				|  |  | +	}
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				|  |  | +	// No need to login, redirect to the next page.
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				|  |  | +	http.Redirect(w, r, next, codeRedirect)
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				|  |  | +}
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				|  |  | +
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				|  |  | +func logout(t *oauth.Transport, s sessions.Session, w http.ResponseWriter, r *http.Request) {
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				|  |  | +	next := extractPath(r.URL.Query().Get(keyNextPage))
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				|  |  | +	s.Delete(keyToken)
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				|  |  | +	http.Redirect(w, r, next, codeRedirect)
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				|  |  | +}
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				|  |  | +
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				|  |  | +func handleOAuth2Callback(t *oauth.Transport, s sessions.Session, w http.ResponseWriter, r *http.Request) {
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				|  |  | +	next := extractPath(r.URL.Query().Get("state"))
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				|  |  | +	code := r.URL.Query().Get("code")
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				|  |  | +	tk, err := t.Exchange(code)
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				|  |  | +	if err != nil {
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				|  |  | +		// Pass the error message, or allow dev to provide its own
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				|  |  | +		// error handler.
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				|  |  | +		http.Redirect(w, r, PathError, codeRedirect)
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				|  |  | +		return
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				|  |  | +	}
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				|  |  | +	// Store the credentials in the session.
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				|  |  | +	val, _ := json.Marshal(tk)
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				|  |  | +	s.Set(keyToken, val)
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				|  |  | +	http.Redirect(w, r, next, codeRedirect)
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				|  |  | +}
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				|  |  | +
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				|  |  | +func unmarshallToken(s sessions.Session) (t *token) {
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				|  |  | +	if s.Get(keyToken) == nil {
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				|  |  | +		return
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				|  |  | +	}
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				|  |  | +	data := s.Get(keyToken).([]byte)
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				|  |  | +	var tk oauth.Token
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				|  |  | +	json.Unmarshal(data, &tk)
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				|  |  | +	return &token{tk}
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				|  |  | +}
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				|  |  | +
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				|  |  | +func extractPath(next string) string {
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				|  |  | +	n, err := url.Parse(next)
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				|  |  | +	if err != nil {
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				|  |  | +		return "/"
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				|  |  | +	}
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				|  |  | +	return n.Path
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				|  |  | +}
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