oauth2

README

OAuth2 for Go

oauth2 package contains a client implementation for OAuth 2.0 spec.

Installation

go get github.com/eiel/golang-oauth2

Or you can manually git clone the repository to $(go env GOPATH)/src/github.com/eiel/golang-oauth2.

See pkg.go.dev for further documentation and examples.

• pkg.go.dev/github.com/eiel/golang-oauth2
• pkg.go.dev/github.com/eiel/golang-oauth2/google

Policy for new endpoints

We no longer accept new provider-specific packages in this repo if all they do is add a single endpoint variable. If you just want to add a single endpoint, add it to the pkg.go.dev/github.com/eiel/golang-oauth2/endpoints package.

Report Issues / Send Patches

The main issue tracker for the oauth2 repository is located at https://github.com/golang/oauth2/issues.

This repository uses Gerrit for code changes. To learn how to submit changes to this repository, see https://golang.org/doc/contribute.html. In particular:

• Excluding trivial changes, all contributions should be connected to an existing issue.
• API changes must go through the change proposal process before they can be accepted.
• The code owners are listed at dev.golang.org/owners.

Documentation

Overview

Package oauth2 provides support for making OAuth2 authorized and authenticated HTTP requests, as specified in RFC 6749. It can additionally grant authorization with Bearer JWT.

Copyright 2023 The Go Authors. All rights reserved. Use of this source code is governed by a BSD-style license that can be found in the LICENSE file.

Index

• Variables
• func GenerateVerifier() string
• func NewClient(ctx context.Context, src TokenSource) *http.Client
• func RegisterBrokenAuthHeaderProvider(tokenURL string)
• func S256ChallengeFromVerifier(verifier string) string
• type AuthCodeOption
  • func S256ChallengeOption(verifier string) AuthCodeOption
  • func SetAuthURLParam(key, value string) AuthCodeOption
  • func VerifierOption(verifier string) AuthCodeOption
• type AuthStyle
• type Config
  • func (c *Config) AuthCodeURL(state string, opts ...AuthCodeOption) string
  • func (c *Config) Client(ctx context.Context, t *Token) *http.Client
  • func (c *Config) DeviceAccessToken(ctx context.Context, da *DeviceAuthResponse, opts ...AuthCodeOption) (*Token, error)
  • func (c *Config) DeviceAuth(ctx context.Context, opts ...AuthCodeOption) (*DeviceAuthResponse, error)
  • func (c *Config) Exchange(ctx context.Context, code string, opts ...AuthCodeOption) (*Token, error)
  • func (c *Config) PasswordCredentialsToken(ctx context.Context, username, password string) (*Token, error)
  • func (c *Config) TokenSource(ctx context.Context, t *Token) TokenSource
• type DeviceAuthResponse
  • func (d DeviceAuthResponse) MarshalJSON() ([]byte, error)
  • func (c *DeviceAuthResponse) UnmarshalJSON(data []byte) error
• type Endpoint
• type RetrieveError
  • func (r *RetrieveError) Error() string
• type Token
  • func (t *Token) Extra(key string) interface{}
  • func (t *Token) SetAuthHeader(r *http.Request)
  • func (t *Token) Type() string
  • func (t *Token) Valid() bool
  • func (t *Token) WithExtra(extra interface{}) *Token
• type TokenSource
  • func ReuseTokenSource(t *Token, src TokenSource) TokenSource
  • func ReuseTokenSourceWithExpiry(t *Token, src TokenSource, earlyExpiry time.Duration) TokenSource
  • func StaticTokenSource(t *Token) TokenSource
• type Transport
  • func (t *Transport) CancelRequest(req *http.Request)
  • func (t *Transport) RoundTrip(req *http.Request) (*http.Response, error)

Examples

• Config
• Config (CustomHTTP)
• Config.DeviceAuth

Variables

var HTTPClient internal.ContextKey

HTTPClient is the context key to use with golang.org/x/net/context's WithValue function to associate an *http.Client value with a context.

var NoContext = context.TODO()

NoContext is the default context you should supply if not using your own context.Context (see https://golang.org/x/net/context).

Deprecated: Use context.Background() or context.TODO() instead.

Functions

func GenerateVerifier

func GenerateVerifier() string

GenerateVerifier generates a PKCE code verifier with 32 octets of randomness. This follows recommendations in RFC 7636.

A fresh verifier should be generated for each authorization. S256ChallengeOption(verifier) should then be passed to Config.AuthCodeURL (or Config.DeviceAccess) and VerifierOption(verifier) to Config.Exchange (or Config.DeviceAccessToken).

func NewClient

func NewClient(ctx context.Context, src TokenSource) *http.Client

NewClient creates an *http.Client from a Context and TokenSource. The returned client is not valid beyond the lifetime of the context.

Note that if a custom *http.Client is provided via the Context it is used only for token acquisition and is not used to configure the *http.Client returned from NewClient.

As a special case, if src is nil, a non-OAuth2 client is returned using the provided context. This exists to support related OAuth2 packages.

func RegisterBrokenAuthHeaderProvider

func RegisterBrokenAuthHeaderProvider(tokenURL string)

RegisterBrokenAuthHeaderProvider previously did something. It is now a no-op.

Deprecated: this function no longer does anything. Caller code that wants to avoid potential extra HTTP requests made during auto-probing of the provider's auth style should set Endpoint.AuthStyle.

func S256ChallengeFromVerifier

func S256ChallengeFromVerifier(verifier string) string

S256ChallengeFromVerifier returns a PKCE code challenge derived from verifier with method S256.

Prefer to use S256ChallengeOption where possible.

Types

type AuthCodeOption

type AuthCodeOption interface {
	// contains filtered or unexported methods
}

An AuthCodeOption is passed to Config.AuthCodeURL.

var (
	// AccessTypeOnline and AccessTypeOffline are options passed
	// to the Options.AuthCodeURL method. They modify the
	// "access_type" field that gets sent in the URL returned by
	// AuthCodeURL.
	//
	// Online is the default if neither is specified. 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.
	AccessTypeOnline  AuthCodeOption = SetAuthURLParam("access_type", "online")
	AccessTypeOffline AuthCodeOption = SetAuthURLParam("access_type", "offline")

	// ApprovalForce forces the users to view the consent dialog
	// and confirm the permissions request at the URL returned
	// from AuthCodeURL, even if they've already done so.
	ApprovalForce AuthCodeOption = SetAuthURLParam("prompt", "consent")
)

func S256ChallengeOption

func S256ChallengeOption(verifier string) AuthCodeOption

S256ChallengeOption derives a PKCE code challenge derived from verifier with method S256. It should be passed to Config.AuthCodeURL or Config.DeviceAccess only.

func SetAuthURLParam

func SetAuthURLParam(key, value string) AuthCodeOption

SetAuthURLParam builds an AuthCodeOption which passes key/value parameters to a provider's authorization endpoint.

func VerifierOption

func VerifierOption(verifier string) AuthCodeOption

VerifierOption returns a PKCE code verifier AuthCodeOption. It should be passed to Config.Exchange or Config.DeviceAccessToken only.

type AuthStyle

type AuthStyle int

AuthStyle represents how requests for tokens are authenticated to the server.

const (
	// AuthStyleAutoDetect means to auto-detect which authentication
	// style the provider wants by trying both ways and caching
	// the successful way for the future.
	AuthStyleAutoDetect AuthStyle = 0

	// AuthStyleInParams sends the "client_id" and "client_secret"
	// in the POST body as application/x-www-form-urlencoded parameters.
	AuthStyleInParams AuthStyle = 1

	// AuthStyleInHeader sends the client_id and client_password
	// using HTTP Basic Authorization. This is an optional style
	// described in the OAuth2 RFC 6749 section 2.3.1.
	AuthStyleInHeader AuthStyle = 2
)

type Config

type Config struct {
	// ClientID is the application's ID.
	ClientID string

	// ClientSecret is the application's secret.
	ClientSecret string

	// Endpoint contains the resource server's token endpoint
	// URLs. These are constants specific to each server and are
	// often available via site-specific packages, such as
	// google.Endpoint or github.Endpoint.
	Endpoint Endpoint

	// RedirectURL is the URL to redirect users going through
	// the OAuth flow, after the resource owner's URLs.
	RedirectURL string

	// Scope specifies optional requested permissions.
	Scopes []string
	// contains filtered or unexported fields
}

Config describes a typical 3-legged OAuth2 flow, with both the client application information and the server's endpoint URLs. For the client credentials 2-legged OAuth2 flow, see the clientcredentials package (https://github.com/eiel/golang-oauth2/clientcredentials).

Example

package main

import (
	"context"
	"fmt"
	"log"

	"golang.org/x/oauth2"
)

func main() {
	ctx := context.Background()
	conf := &oauth2.Config{
		ClientID:     "YOUR_CLIENT_ID",
		ClientSecret: "YOUR_CLIENT_SECRET",
		Scopes:       []string{"SCOPE1", "SCOPE2"},
		Endpoint: oauth2.Endpoint{
			AuthURL:  "https://provider.com/o/oauth2/auth",
			TokenURL: "https://provider.com/o/oauth2/token",
		},
	}

	// use PKCE to protect against CSRF attacks
	// https://www.ietf.org/archive/id/draft-ietf-oauth-security-topics-22.html#name-countermeasures-6
	verifier := oauth2.GenerateVerifier()

	// Redirect user to consent page to ask for permission
	// for the scopes specified above.
	url := conf.AuthCodeURL("state", oauth2.AccessTypeOffline, oauth2.S256ChallengeOption(verifier))
	fmt.Printf("Visit the URL for the auth dialog: %v", url)

	// Use the authorization code that is pushed to the redirect
	// URL. Exchange will do the handshake to retrieve the
	// initial access token. The HTTP Client returned by
	// conf.Client will refresh the token as necessary.
	var code string
	if _, err := fmt.Scan(&code); err != nil {
		log.Fatal(err)
	}
	tok, err := conf.Exchange(ctx, code, oauth2.VerifierOption(verifier))
	if err != nil {
		log.Fatal(err)
	}

	client := conf.Client(ctx, tok)
	client.Get("...")
}

Example (CustomHTTP)

package main

import (
	"context"
	"fmt"
	"log"
	"net/http"
	"time"

	"golang.org/x/oauth2"
)

func main() {
	ctx := context.Background()

	conf := &oauth2.Config{
		ClientID:     "YOUR_CLIENT_ID",
		ClientSecret: "YOUR_CLIENT_SECRET",
		Scopes:       []string{"SCOPE1", "SCOPE2"},
		Endpoint: oauth2.Endpoint{
			TokenURL: "https://provider.com/o/oauth2/token",
			AuthURL:  "https://provider.com/o/oauth2/auth",
		},
	}

	// Redirect user to consent page to ask for permission
	// for the scopes specified above.
	url := conf.AuthCodeURL("state", oauth2.AccessTypeOffline)
	fmt.Printf("Visit the URL for the auth dialog: %v", url)

	// Use the authorization code that is pushed to the redirect
	// URL. Exchange will do the handshake to retrieve the
	// initial access token. The HTTP Client returned by
	// conf.Client will refresh the token as necessary.
	var code string
	if _, err := fmt.Scan(&code); err != nil {
		log.Fatal(err)
	}

	// Use the custom HTTP client when requesting a token.
	httpClient := &http.Client{Timeout: 2 * time.Second}
	ctx = context.WithValue(ctx, oauth2.HTTPClient, httpClient)

	tok, err := conf.Exchange(ctx, code)
	if err != nil {
		log.Fatal(err)
	}

	client := conf.Client(ctx, tok)
	_ = client
}

func (*Config) AuthCodeURL

func (c *Config) AuthCodeURL(state string, opts ...AuthCodeOption) string

AuthCodeURL returns a URL to OAuth 2.0 provider's consent page that asks for permissions for the required scopes explicitly.

State is an opaque value used by the client to maintain state between the request and callback. The authorization server includes this value when redirecting the user agent back to the client.

Opts may include AccessTypeOnline or AccessTypeOffline, as well as ApprovalForce.

To protect against CSRF attacks, opts should include a PKCE challenge (S256ChallengeOption). Not all servers support PKCE. An alternative is to generate a random state parameter and verify it after exchange. See https://datatracker.ietf.org/doc/html/rfc6749#section-10.12 (predating PKCE), https://www.oauth.com/oauth2-servers/pkce/ and https://www.ietf.org/archive/id/draft-ietf-oauth-v2-1-09.html#name-cross-site-request-forgery (describing both approaches)

func (*Config) Client

func (c *Config) Client(ctx context.Context, t *Token) *http.Client

Client returns an HTTP client using the provided token. The token will auto-refresh as necessary. The underlying HTTP transport will be obtained using the provided context. The returned client and its Transport should not be modified.

func (*Config) DeviceAccessToken

func (c *Config) DeviceAccessToken(ctx context.Context, da *DeviceAuthResponse, opts ...AuthCodeOption) (*Token, error)

DeviceAccessToken polls the server to exchange a device code for a token.

func (*Config) DeviceAuth

func (c *Config) DeviceAuth(ctx context.Context, opts ...AuthCodeOption) (*DeviceAuthResponse, error)

DeviceAuth returns a device auth struct which contains a device code and authorization information provided for users to enter on another device.

Example

var config Config
ctx := context.Background()
response, err := config.DeviceAuth(ctx)
if err != nil {
	panic(err)
}
fmt.Printf("please enter code %s at %s\n", response.UserCode, response.VerificationURI)
token, err := config.DeviceAccessToken(ctx, response)
if err != nil {
	panic(err)
}
fmt.Println(token)

func (*Config) Exchange

func (c *Config) Exchange(ctx context.Context, code string, opts ...AuthCodeOption) (*Token, error)

Exchange converts an authorization code into a token.

It is used after a resource provider redirects the user back to the Redirect URI (the URL obtained from AuthCodeURL).

The provided context optionally controls which HTTP client is used. See the HTTPClient variable.

The code will be in the *http.Request.FormValue("code"). Before calling Exchange, be sure to validate FormValue("state") if you are using it to protect against CSRF attacks.

If using PKCE to protect against CSRF attacks, opts should include a VerifierOption.

func (*Config) PasswordCredentialsToken

func (c *Config) PasswordCredentialsToken(ctx context.Context, username, password string) (*Token, error)

PasswordCredentialsToken converts a resource owner username and password pair into a token.

Per the RFC, this grant type should only be used "when there is a high degree of trust between the resource owner and the client (e.g., the client is part of the device operating system or a highly privileged application), and when other authorization grant types are not available." See https://tools.ietf.org/html/rfc6749#section-4.3 for more info.

The provided context optionally controls which HTTP client is used. See the HTTPClient variable.

func (*Config) TokenSource

func (c *Config) TokenSource(ctx context.Context, t *Token) TokenSource

TokenSource returns a TokenSource that returns t until t expires, automatically refreshing it as necessary using the provided context.

Most users will use Config.Client instead.

type DeviceAuthResponse

type DeviceAuthResponse struct {
	// DeviceCode
	DeviceCode string `json:"device_code"`
	// UserCode is the code the user should enter at the verification uri
	UserCode string `json:"user_code"`
	// VerificationURI is where user should enter the user code
	VerificationURI string `json:"verification_uri"`
	// VerificationURIComplete (if populated) includes the user code in the verification URI. This is typically shown to the user in non-textual form, such as a QR code.
	VerificationURIComplete string `json:"verification_uri_complete,omitempty"`
	// Expiry is when the device code and user code expire
	Expiry time.Time `json:"expires_in,omitempty"`
	// Interval is the duration in seconds that Poll should wait between requests
	Interval int64 `json:"interval,omitempty"`
}

DeviceAuthResponse describes a successful RFC 8628 Device Authorization Response https://datatracker.ietf.org/doc/html/rfc8628#section-3.2

func (DeviceAuthResponse) MarshalJSON

func (d DeviceAuthResponse) MarshalJSON() ([]byte, error)

func (*DeviceAuthResponse) UnmarshalJSON

func (c *DeviceAuthResponse) UnmarshalJSON(data []byte) error

type Endpoint

type Endpoint struct {
	AuthURL       string
	DeviceAuthURL string
	TokenURL      string

	// AuthStyle optionally specifies how the endpoint wants the
	// client ID & client secret sent. The zero value means to
	// auto-detect.
	AuthStyle AuthStyle
}

Endpoint represents an OAuth 2.0 provider's authorization and token endpoint URLs.

type RetrieveError

type RetrieveError struct {
	Response *http.Response
	// Body is the body that was consumed by reading Response.Body.
	// It may be truncated.
	Body []byte
	// ErrorCode is RFC 6749's 'error' parameter.
	ErrorCode string
	// ErrorDescription is RFC 6749's 'error_description' parameter.
	ErrorDescription string
	// ErrorURI is RFC 6749's 'error_uri' parameter.
	ErrorURI string
}

RetrieveError is the error returned when the token endpoint returns a non-2XX HTTP status code or populates RFC 6749's 'error' parameter. https://datatracker.ietf.org/doc/html/rfc6749#section-5.2

func (*RetrieveError) Error

func (r *RetrieveError) Error() string

type Token

type Token struct {
	// AccessToken is the token that authorizes and authenticates
	// the requests.
	AccessToken string `json:"access_token"`

	// TokenType is the type of token.
	// The Type method returns either this or "Bearer", the default.
	TokenType string `json:"token_type,omitempty"`

	// RefreshToken is a token that's used by the application
	// (as opposed to the user) to refresh the access token
	// if it expires.
	RefreshToken string `json:"refresh_token,omitempty"`

	// Expiry is the optional expiration time of the access token.
	//
	// If zero, TokenSource implementations will reuse the same
	// token forever and RefreshToken or equivalent
	// mechanisms for that TokenSource will not be used.
	Expiry time.Time `json:"expiry,omitempty"`
	// contains filtered or unexported fields
}

Token represents the credentials used to authorize the requests to access protected resources on the OAuth 2.0 provider's backend.

Most users of this package should not access fields of Token directly. They're exported mostly for use by related packages implementing derivative OAuth2 flows.

func (*Token) Extra

func (t *Token) Extra(key string) interface{}

Extra returns an extra field. Extra fields are key-value pairs returned by the server as a part of the token retrieval response.

func (*Token) SetAuthHeader

func (t *Token) SetAuthHeader(r *http.Request)

SetAuthHeader sets the Authorization header to r using the access token in t.

This method is unnecessary when using Transport or an HTTP Client returned by this package.

func (*Token) Type

func (t *Token) Type() string

Type returns t.TokenType if non-empty, else "Bearer".

func (*Token) Valid

func (t *Token) Valid() bool

Valid reports whether t is non-nil, has an AccessToken, and is not expired.

func (*Token) WithExtra

func (t *Token) WithExtra(extra interface{}) *Token

WithExtra returns a new Token that's a clone of t, but using the provided raw extra map. This is only intended for use by packages implementing derivative OAuth2 flows.

type TokenSource

type TokenSource interface {
	// Token returns a token or an error.
	// Token must be safe for concurrent use by multiple goroutines.
	// The returned Token must not be modified.
	Token() (*Token, error)
}

A TokenSource is anything that can return a token.

func ReuseTokenSource

func ReuseTokenSource(t *Token, src TokenSource) TokenSource

ReuseTokenSource returns a TokenSource which repeatedly returns the same token as long as it's valid, starting with t. When its cached token is invalid, a new token is obtained from src.

ReuseTokenSource is typically used to reuse tokens from a cache (such as a file on disk) between runs of a program, rather than obtaining new tokens unnecessarily.

The initial token t may be nil, in which case the TokenSource is wrapped in a caching version if it isn't one already. This also means it's always safe to wrap ReuseTokenSource around any other TokenSource without adverse effects.

func ReuseTokenSourceWithExpiry

func ReuseTokenSourceWithExpiry(t *Token, src TokenSource, earlyExpiry time.Duration) TokenSource

ReuseTokenSource returns a TokenSource that acts in the same manner as the TokenSource returned by ReuseTokenSource, except the expiry buffer is configurable. The expiration time of a token is calculated as t.Expiry.Add(-earlyExpiry).

func StaticTokenSource

func StaticTokenSource(t *Token) TokenSource

StaticTokenSource returns a TokenSource that always returns the same token. Because the provided token t is never refreshed, StaticTokenSource is only useful for tokens that never expire.

type Transport

type Transport struct {
	// Source supplies the token to add to outgoing requests'
	// Authorization headers.
	Source TokenSource

	// Base is the base RoundTripper used to make HTTP requests.
	// If nil, http.DefaultTransport is used.
	Base http.RoundTripper
}

Transport is an http.RoundTripper that makes OAuth 2.0 HTTP requests, wrapping a base RoundTripper and adding an Authorization header with a token from the supplied Sources.

Transport is a low-level mechanism. Most code will use the higher-level Config.Client method instead.

func (*Transport) CancelRequest

func (t *Transport) CancelRequest(req *http.Request)

CancelRequest does nothing. It used to be a legacy cancellation mechanism but now only it only logs on first use to warn that it's deprecated.

Deprecated: use contexts for cancellation instead.

func (*Transport) RoundTrip

func (t *Transport) RoundTrip(req *http.Request) (*http.Response, error)

RoundTrip authorizes and authenticates the request with an access token from Transport's Source.