gologin

README

gologin

Package gologin provides chainable login http.Handler's for Google, GitHub, Twitter, Facebook, Bitbucket, Tumblr, or any OAuth1 or OAuth2 authentication providers.

Choose a subpackage. Register the LoginHandler and CallbackHandler for web logins or the TokenHandler for (mobile) token logins. Get the authenticated user or access token from the request context.

See examples for tutorials with apps you can run from the command line.

Features

• LoginHandler and CallbackHandler support web login flows
• TokenHandler supports native mobile token login flows
• Obtain the user or access token from the context
• Configurable OAuth 2 state parameter handling (CSRF protection)
• Configurable OAuth 1 request secret handling

Docs

Read GoDoc or check the examples.

Overview

Package gologin provides http.Handler's which can be chained together to implement authorization flows by passing data (e.g. tokens, users) via the request context. gologin handlers take success and failure next http.Handler's to be called when authentication succeeds or fails. Chaining allows advanced customization, if desired. Once authentication succeeds, your success handler will have access to the user's access token and associated User/Account.

Usage

Choose a subpackage such as github or twitter. LoginHandler and Callback http.Handler's chain together lower level oauth1 or oauth2 handlers to authenticate users and fetch the GitHub or Twitter User, before calling your success http.Handler.

Let's walk through GitHub and Twitter web login examples.

GitHub OAuth2

Register the LoginHandler and CallbackHandler on your http.ServeMux.

import (
    ...
    "github.com/dghubble/gologin/v2"
	"github.com/dghubble/gologin/v2/github"
	"golang.org/x/oauth2"
	githubOAuth2 "golang.org/x/oauth2/github"
)
...

config := &oauth2.Config{
    ClientID:     "GithubClientID",
    ClientSecret: "GithubClientSecret",
    RedirectURL:  "http://localhost:8080/callback",
    Endpoint:     githubOAuth2.Endpoint,
}
mux := http.NewServeMux()
stateConfig := gologin.DebugOnlyCookieConfig
mux.Handle("/login", github.StateHandler(stateConfig, github.LoginHandler(config, nil)))
mux.Handle("/callback", github.StateHandler(stateConfig, github.CallbackHandler(config, issueSession(), nil)))

The StateHandler checks for an OAuth2 state parameter cookie, generates a non-guessable state as a short-lived cookie if missing, and passes the state value in the ctx. The CookieConfig allows the cookie name or expiration (default 60 seconds) to be configured. In production, use a config like gologin.DefaultCookieConfig which sets Secure true to require cookies be sent over HTTPS. If you wish to persist state parameters a different way, you may chain your own http.Handler. (info)

The github LoginHandler reads the state from the ctx and redirects to the AuthURL (at github.com) to prompt the user to grant access. Passing nil for the failure handler just means the DefaultFailureHandler should be used, which reports errors. (info)

The github CallbackHandler receives an auth code and state OAuth2 redirection, validates the state against the state in the ctx, and exchanges the auth code for an OAuth2 Token. The github CallbackHandler wraps the lower level oauth2 CallbackHandler to further use the Token to obtain the GitHub User before calling through to the success or failure handlers.

Next, write the success http.Handler to do something with the Token and GitHub User added to the ctx.

func issueSession() http.Handler {
    fn := func(w http.ResponseWriter, req *http.Request) {
        ctx := req.Context()
        token, _ := oauth2Login.TokenFromContext(ctx)
        githubUser, err := github.UserFromContext(ctx)
        // handle errors and grant the visitor a session (cookie, token, etc.)
    }
    return http.HandlerFunc(fn)
}

See the GitHub tutorial for a web app you can run from the command line.

Twitter OAuth1

Register the LoginHandler and CallbackHandler on your http.ServeMux.

config := &oauth1.Config{
    ConsumerKey:    "TwitterConsumerKey",
    ConsumerSecret: "TwitterConsumerSecret",
    CallbackURL:    "http://localhost:8080/callback",
    Endpoint:       twitterOAuth1.AuthorizeEndpoint,
}
mux := http.NewServeMux()
mux.Handle("/login", twitter.LoginHandler(config, nil))
mux.Handle("/callback", twitter.CallbackHandler(config, issueSession(), nil))

The twitter LoginHandler obtains a request token and secret, adds them to the ctx, and redirects to the AuthorizeURL to prompt the user to grant access. Passing nil for the failure handler just means the DefaultFailureHandler should be used, which reports errors. (info)

The twitter CallbackHandler receives an OAuth1 token and verifier, reads the request secret from the ctx, and obtains an OAuth1 access token and secret. The twitter CallbackHandler wraps the lower level oauth1 CallbackHandler to further use the access token/secret to obtain the Twitter User before calling through to the success or failure handlers.

Next, write the success http.Handler to do something with the access token/secret and Twitter User added to the ctx.

func success() http.Handler {
    fn := func(w http.ResponseWriter, req *http.Request) {
        ctx := req.Context()
        accessToken, accessSecret, _ := oauth1Login.AccessTokenFromContext(ctx)
        twitterUser, err := twitter.UserFromContext(ctx)
        // handle errors and grant the visitor a session (cookie, token, etc.)
    }
    return http.HandlerFunc(fn)
}

*Note: Some OAuth1 providers (not Twitter), require the request secret be persisted until the callback is received. For this reason, the lower level oauth1 package splits LoginHandler functionality into a LoginHandler and AuthRedirectHandler. Provider packages, like tumblr, chain these together for you, but the lower level handlers are there if needed.

See the Twitter tutorial for a web app you can run from the command line.

State Parameters

OAuth2 StateHandler implements OAuth 2 RFC 6749 10.12 CSRF Protection using non-guessable values in short-lived HTTPS-only cookies to provide reasonable assurance the user in the login phase and callback phase are the same. If you wish to implement this differently, write a http.Handler which sets a state in the ctx, which is expected by LoginHandler and CallbackHandler.

You may use oauth2.WithState(context.Context, state string) for this. docs

Failure Handlers

If you wish to define your own failure http.Handler, you can get the error from the ctx using gologin.ErrorFromContext(ctx).

Mobile

Twitter includes a TokenHandler which can be useful for building APIs for mobile devices which use Login with Twitter.

Goals

Create small, chainable handlers to correctly implement the steps of common authentication flows. Handle provider-specific validation requirements.

Motivations

Package gologin implements authorization flow steps with chained handlers.

• Authentication should be performed with chainable handlers to allow customization, swapping, or adding additional steps easily.
• Authentication should be orthogonal to the session system. Let users choose their session/token library.
• OAuth2 State CSRF should be included out of the box, but easy to customize.
• Packages should import only what is required. OAuth1 and OAuth2 packages are separate.
• http.Handler and context are powerful, flexible, and in the standard library.

Projects goth and gomniauth aim to provide a similar login solution with a different design. Check them out if you decide you don't like the ideas in gologin.

Contributing

New auth providers can be implemented by composing the handlers in the oauth1 or oauth2 subpackages. See the Contributing Guide.

License

MIT License

Documentation

Index

• Variables
• func ErrorFromContext(ctx context.Context) error
• func WithError(ctx context.Context, err error) context.Context
• type CookieConfig

Variables

var DebugOnlyCookieConfig = CookieConfig{
	Name:     "gologin-temporary-cookie",
	Path:     "/",
	MaxAge:   600,
	HTTPOnly: true,
	Secure:   false,
	SameSite: http.SameSiteLaxMode,
}

DebugOnlyCookieConfig configures creation of short-lived temporary http.Cookie's which do NOT require cookies be sent over HTTPS! Use this config for development only.

var DefaultCookieConfig = CookieConfig{
	Name:     "gologin-temporary-cookie",
	Path:     "/",
	MaxAge:   600,
	HTTPOnly: true,
	Secure:   true,
	SameSite: http.SameSiteLaxMode,
}

DefaultCookieConfig configures short-lived temporary http.Cookie creation.

var DefaultFailureHandler = http.HandlerFunc(failureHandler)

DefaultFailureHandler responds with a 400 status code and message parsed from the ctx.

Functions

func ErrorFromContext

func ErrorFromContext(ctx context.Context) error

ErrorFromContext returns the error value from the ctx or an error that the context was missing an error value.

func WithError

func WithError(ctx context.Context, err error) context.Context

WithError returns a copy of ctx that stores the given error value.

Types

type CookieConfig

type CookieConfig struct {
	// Name is the desired cookie name.
	Name string
	// Domain sets the cookie domain. Defaults to the host name of the responding
	// server when left zero valued.
	Domain string
	// Path sets the cookie path. Defaults to the path of the URL responding to
	// the request when left zero valued.
	Path string
	// MaxAge=0 means no 'Max-Age' attribute should be set.
	// MaxAge<0 means delete cookie now, equivalently 'Max-Age: 0'.
	// MaxAge>0 means Max-Age attribute present and given in seconds.
	// Cookie 'Expires' will be set (or left unset) according to MaxAge
	MaxAge int
	// HTTPOnly indicates whether the browser should prohibit a cookie from
	// being accessible via Javascript. Recommended true.
	HTTPOnly bool
	// Secure flag indicating to the browser that the cookie should only be
	// transmitted over a TLS HTTPS connection. Recommended true in production.
	Secure bool
	// SameSite attribute modes indicates that a browser not send a cookie in
	// cross-site requests.
	SameSite http.SameSite
}

CookieConfig configures http.Cookie creation.