harness-drone/shared/oauth2/oauth2.go

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2015-09-30 01:21:17 +00:00
// Copyright 2011 The goauth2 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 oauth supports making OAuth2-authenticated HTTP requests.
//
// Example usage:
//
// // Specify your configuration. (typically as a global variable)
// var config = &oauth.Config{
// ClientId: YOUR_CLIENT_ID,
// ClientSecret: YOUR_CLIENT_SECRET,
// Scope: "https://www.googleapis.com/auth/buzz",
// AuthURL: "https://accounts.google.com/o/oauth2/auth",
// TokenURL: "https://accounts.google.com/o/oauth2/token",
// RedirectURL: "http://you.example.org/handler",
// }
//
// // A landing page redirects to the OAuth provider to get the auth code.
// func landing(w http.ResponseWriter, r *http.Request) {
// http.Redirect(w, r, config.AuthCodeURL("foo"), http.StatusFound)
// }
//
// // The user will be redirected back to this handler, that takes the
// // "code" query parameter and Exchanges it for an access token.
// func handler(w http.ResponseWriter, r *http.Request) {
// t := &oauth.Transport{Config: config}
// t.Exchange(r.FormValue("code"))
// // The Transport now has a valid Token. Create an *http.Client
// // with which we can make authenticated API requests.
// c := t.Client()
// c.Post(...)
// // ...
// // btw, r.FormValue("state") == "foo"
// }
//
package oauth2
import (
"encoding/json"
"errors"
"fmt"
"io"
"io/ioutil"
"mime"
"net/http"
"net/url"
"os"
"strconv"
"strings"
"sync"
"time"
)
// OAuthError is the error type returned by many operations.
//
// In retrospect it should not exist. Don't depend on it.
type OAuthError struct {
prefix string
msg string
}
func (oe OAuthError) Error() string {
return "OAuthError: " + oe.prefix + ": " + oe.msg
}
// Cache specifies the methods that implement a Token cache.
type Cache interface {
Token() (*Token, error)
PutToken(*Token) error
}
// CacheFile implements Cache. Its value is the name of the file in which
// the Token is stored in JSON format.
type CacheFile string
func (f CacheFile) Token() (*Token, error) {
file, err := os.Open(string(f))
if err != nil {
return nil, OAuthError{"CacheFile.Token", err.Error()}
}
defer file.Close()
tok := &Token{}
if err := json.NewDecoder(file).Decode(tok); err != nil {
return nil, OAuthError{"CacheFile.Token", err.Error()}
}
return tok, nil
}
func (f CacheFile) PutToken(tok *Token) error {
file, err := os.OpenFile(string(f), os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0600)
if err != nil {
return OAuthError{"CacheFile.PutToken", err.Error()}
}
if err := json.NewEncoder(file).Encode(tok); err != nil {
file.Close()
return OAuthError{"CacheFile.PutToken", err.Error()}
}
if err := file.Close(); err != nil {
return OAuthError{"CacheFile.PutToken", err.Error()}
}
return nil
}
// Config is the configuration of an OAuth consumer.
type Config struct {
// ClientId is the OAuth client identifier used when communicating with
// the configured OAuth provider.
ClientId string
// ClientSecret is the OAuth client secret used when communicating with
// the configured OAuth provider.
ClientSecret string
// Scope identifies the level of access being requested. Multiple scope
// values should be provided as a space-delimited string.
Scope string
// AuthURL is the URL the user will be directed to in order to grant
// access.
AuthURL string
// TokenURL is the URL used to retrieve OAuth tokens.
TokenURL string
// RedirectURL is the URL to which the user will be returned after
// granting (or denying) access.
RedirectURL string
// TokenCache allows tokens to be cached for subsequent requests.
TokenCache Cache
// AccessType is an OAuth extension that gets sent as the
// "access_type" field in the URL from AuthCodeURL.
// See https://developers.google.com/accounts/docs/OAuth2WebServer.
// It may be "online" (the default) or "offline".
// If your application needs to refresh access tokens when the
// user is not present at the browser, then use offline. This
// will result in your application obtaining a refresh token
// the first time your application exchanges an authorization
// code for a user.
AccessType string
// ApprovalPrompt indicates whether the user should be
// re-prompted for consent. If set to "auto" (default) the
// user will be prompted only if they haven't previously
// granted consent and the code can only be exchanged for an
// access token.
// If set to "force" the user will always be prompted, and the
// code can be exchanged for a refresh token.
ApprovalPrompt string
}
// Token contains an end-user's tokens.
// This is the data you must store to persist authentication.
type Token struct {
AccessToken string
RefreshToken string
Expiry time.Time // If zero the token has no (known) expiry time.
// Extra optionally contains extra metadata from the server
// when updating a token. The only current key that may be
// populated is "id_token". It may be nil and will be
// initialized as needed.
Extra map[string]string
}
// Expired reports whether the token has expired or is invalid.
func (t *Token) Expired() bool {
if t.AccessToken == "" {
return true
}
if t.Expiry.IsZero() {
return false
}
return t.Expiry.Before(time.Now())
}
// Transport implements http.RoundTripper. When configured with a valid
// Config and Token it can be used to make authenticated HTTP requests.
//
// t := &oauth.Transport{config}
// t.Exchange(code)
// // t now contains a valid Token
// r, _, err := t.Client().Get("http://example.org/url/requiring/auth")
//
// It will automatically refresh the Token if it can,
// updating the supplied Token in place.
type Transport struct {
*Config
*Token
// mu guards modifying the token.
mu sync.Mutex
// Transport is the HTTP transport to use when making requests.
// It will default to http.DefaultTransport if nil.
// (It should never be an oauth.Transport.)
Transport http.RoundTripper
}
// Client returns an *http.Client that makes OAuth-authenticated requests.
func (t *Transport) Client() *http.Client {
return &http.Client{Transport: t}
}
func (t *Transport) transport() http.RoundTripper {
if t.Transport != nil {
return t.Transport
}
return http.DefaultTransport
}
// AuthCodeURL returns a URL that the end-user should be redirected to,
// so that they may obtain an authorization code.
func (c *Config) AuthCodeURL(state string) string {
url_, err := url.Parse(c.AuthURL)
if err != nil {
panic("AuthURL malformed: " + err.Error())
}
if err := url_.Query().Get("error"); err != "" {
panic("AuthURL contains error: " + err)
}
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q := url.Values{
"response_type": {"code"},
"client_id": {c.ClientId},
"state": condVal(state),
"scope": condVal(c.Scope),
"redirect_uri": condVal(c.RedirectURL),
"access_type": condVal(c.AccessType),
"approval_prompt": condVal(c.ApprovalPrompt),
}.Encode()
if url_.RawQuery == "" {
url_.RawQuery = q
} else {
url_.RawQuery += "&" + q
}
return url_.String()
}
func condVal(v string) []string {
if v == "" {
return nil
}
return []string{v}
}
// Exchange takes a code and gets access Token from the remote server.
func (t *Transport) Exchange(code string) (*Token, error) {
if t.Config == nil {
return nil, OAuthError{"Exchange", "no Config supplied"}
}
// If the transport or the cache already has a token, it is
// passed to `updateToken` to preserve existing refresh token.
tok := t.Token
if tok == nil && t.TokenCache != nil {
tok, _ = t.TokenCache.Token()
}
if tok == nil {
tok = new(Token)
}
err := t.updateToken(tok, url.Values{
"grant_type": {"authorization_code"},
"redirect_uri": {t.RedirectURL},
"scope": {t.Scope},
"code": {code},
})
if err != nil {
return nil, err
}
t.Token = tok
if t.TokenCache != nil {
return tok, t.TokenCache.PutToken(tok)
}
return tok, nil
}
// RoundTrip executes a single HTTP transaction using the Transport's
// Token as authorization headers.
//
// This method will attempt to renew the Token if it has expired and may return
// an error related to that Token renewal before attempting the client request.
// If the Token cannot be renewed a non-nil os.Error value will be returned.
// If the Token is invalid callers should expect HTTP-level errors,
// as indicated by the Response's StatusCode.
func (t *Transport) RoundTrip(req *http.Request) (*http.Response, error) {
accessToken, err := t.getAccessToken()
if err != nil {
return nil, err
}
// To set the Authorization header, we must make a copy of the Request
// so that we don't modify the Request we were given.
// This is required by the specification of http.RoundTripper.
req = cloneRequest(req)
req.Header.Set("Authorization", "Bearer "+accessToken)
// Make the HTTP request.
return t.transport().RoundTrip(req)
}
func (t *Transport) getAccessToken() (string, error) {
t.mu.Lock()
defer t.mu.Unlock()
if t.Token == nil {
if t.Config == nil {
return "", OAuthError{"RoundTrip", "no Config supplied"}
}
if t.TokenCache == nil {
return "", OAuthError{"RoundTrip", "no Token supplied"}
}
var err error
t.Token, err = t.TokenCache.Token()
if err != nil {
return "", err
}
}
// Refresh the Token if it has expired.
if t.Expired() {
if err := t.Refresh(); err != nil {
return "", err
}
}
if t.AccessToken == "" {
return "", errors.New("no access token obtained from refresh")
}
return t.AccessToken, nil
}
// cloneRequest returns a clone of the provided *http.Request.
// The clone is a shallow copy of the struct and its Header map.
func cloneRequest(r *http.Request) *http.Request {
// shallow copy of the struct
r2 := new(http.Request)
*r2 = *r
// deep copy of the Header
r2.Header = make(http.Header)
for k, s := range r.Header {
r2.Header[k] = s
}
return r2
}
// Refresh renews the Transport's AccessToken using its RefreshToken.
func (t *Transport) Refresh() error {
if t.Token == nil {
return OAuthError{"Refresh", "no existing Token"}
}
if t.RefreshToken == "" {
return OAuthError{"Refresh", "Token expired; no Refresh Token"}
}
if t.Config == nil {
return OAuthError{"Refresh", "no Config supplied"}
}
err := t.updateToken(t.Token, url.Values{
"grant_type": {"refresh_token"},
"refresh_token": {t.RefreshToken},
})
if err != nil {
return err
}
if t.TokenCache != nil {
return t.TokenCache.PutToken(t.Token)
}
return nil
}
// AuthenticateClient gets an access Token using the client_credentials grant
// type.
func (t *Transport) AuthenticateClient() error {
if t.Config == nil {
return OAuthError{"Exchange", "no Config supplied"}
}
if t.Token == nil {
t.Token = &Token{}
}
return t.updateToken(t.Token, url.Values{"grant_type": {"client_credentials"}})
}
// providerAuthHeaderWorks reports whether the OAuth2 server identified by the tokenURL
// implements the OAuth2 spec correctly
// See https://code.google.com/p/goauth2/issues/detail?id=31 for background.
// In summary:
// - Reddit only accepts client secret in the Authorization header
// - Dropbox accepts either it in URL param or Auth header, but not both.
// - Google only accepts URL param (not spec compliant?), not Auth header
func providerAuthHeaderWorks(tokenURL string) bool {
if strings.HasPrefix(tokenURL, "https://accounts.google.com/") ||
strings.HasPrefix(tokenURL, "https://github.com/") ||
strings.HasPrefix(tokenURL, "https://api.instagram.com/") ||
strings.HasPrefix(tokenURL, "https://www.douban.com/") {
// Some sites fail to implement the OAuth2 spec fully.
return false
}
// Assume the provider implements the spec properly
// otherwise. We can add more exceptions as they're
// discovered. We will _not_ be adding configurable hooks
// to this package to let users select server bugs.
return true
}
// updateToken mutates both tok and v.
func (t *Transport) updateToken(tok *Token, v url.Values) error {
v.Set("client_id", t.ClientId)
v.Set("client_secret", t.ClientSecret)
client := &http.Client{Transport: t.transport()}
req, err := http.NewRequest("POST", t.TokenURL, strings.NewReader(v.Encode()))
if err != nil {
return err
}
req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
req.SetBasicAuth(t.ClientId, t.ClientSecret)
r, err := client.Do(req)
if err != nil {
return err
}
defer r.Body.Close()
if r.StatusCode != 200 {
return OAuthError{"updateToken", "Unexpected HTTP status " + r.Status}
}
var b struct {
Access string `json:"access_token"`
Refresh string `json:"refresh_token"`
ExpiresIn int64 `json:"expires_in"` // seconds
Id string `json:"id_token"`
}
body, err := ioutil.ReadAll(io.LimitReader(r.Body, 1<<20))
if err != nil {
return err
}
content, _, _ := mime.ParseMediaType(r.Header.Get("Content-Type"))
switch content {
case "application/x-www-form-urlencoded", "text/plain":
vals, err := url.ParseQuery(string(body))
if err != nil {
return err
}
b.Access = vals.Get("access_token")
b.Refresh = vals.Get("refresh_token")
b.ExpiresIn, _ = strconv.ParseInt(vals.Get("expires_in"), 10, 64)
b.Id = vals.Get("id_token")
default:
if err = json.Unmarshal(body, &b); err != nil {
return fmt.Errorf("got bad response from server: %q", body)
}
}
if b.Access == "" {
return errors.New("received empty access token from authorization server")
}
tok.AccessToken = b.Access
// Don't overwrite `RefreshToken` with an empty value
if b.Refresh != "" {
tok.RefreshToken = b.Refresh
}
if b.ExpiresIn == 0 {
tok.Expiry = time.Time{}
} else {
tok.Expiry = time.Now().Add(time.Duration(b.ExpiresIn) * time.Second)
}
if b.Id != "" {
if tok.Extra == nil {
tok.Extra = make(map[string]string)
}
tok.Extra["id_token"] = b.Id
}
return nil
}