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

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

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