Oauth/token (#7)

* add host and protocol options * some fiddling * tidying up and comments * tick off /oauth/token * tidying a bit * tidying * go mod tidy * allow attaching middleware to server * add middleware * more user friendly * add comments * comments * store account + app * tidying * lots of restructuring * lint + tidy
2021-03-22 22:26:54 +01:00
parent 4194f8d88f
commit aa9ce272dc
30 changed files with 1346 additions and 977 deletions
--- a/internal/module/oauth/oauth.go
+++ b/internal/module/oauth/oauth.go
@ -0,0 +1,510 @@
+/*
+   GoToSocial
+   Copyright (C) 2021 GoToSocial Authors admin@gotosocial.org
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU Affero General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU Affero General Public License for more details.
+
+   You should have received a copy of the GNU Affero General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+// Package oauth is a module that provides oauth functionality to a router.
+// It adds the following paths:
+//    /api/v1/apps
+//    /auth/sign_in
+//    /oauth/token
+//    /oauth/authorize
+// It also includes the oauthTokenMiddleware, which can be attached to a router to authenticate every request by Bearer token.
+package oauth
+
+import (
+	"fmt"
+	"net/http"
+	"net/url"
+
+	"github.com/gin-contrib/sessions"
+	"github.com/gin-gonic/gin"
+	"github.com/google/uuid"
+	"github.com/gotosocial/gotosocial/internal/db"
+	"github.com/gotosocial/gotosocial/internal/gtsmodel"
+	"github.com/gotosocial/gotosocial/internal/module"
+	"github.com/gotosocial/gotosocial/internal/router"
+	"github.com/gotosocial/gotosocial/pkg/mastotypes"
+	"github.com/gotosocial/oauth2/v4"
+	"github.com/gotosocial/oauth2/v4/errors"
+	"github.com/gotosocial/oauth2/v4/manage"
+	"github.com/gotosocial/oauth2/v4/server"
+	"github.com/sirupsen/logrus"
+	"golang.org/x/crypto/bcrypt"
+)
+
+const (
+	appsPath           = "/api/v1/apps"
+	authSignInPath     = "/auth/sign_in"
+	oauthTokenPath     = "/oauth/token"
+	oauthAuthorizePath = "/oauth/authorize"
+)
+
+// oauthModule is an oauth2 oauthModule that satisfies the ClientAPIModule interface
+type oauthModule struct {
+	oauthManager *manage.Manager
+	oauthServer  *server.Server
+	db           db.DB
+	log          *logrus.Logger
+}
+
+type login struct {
+	Email    string `form:"username"`
+	Password string `form:"password"`
+}
+
+// New returns a new oauth module
+func New(ts oauth2.TokenStore, cs oauth2.ClientStore, db db.DB, log *logrus.Logger) module.ClientAPIModule {
+	manager := manage.NewDefaultManager()
+	manager.MapTokenStorage(ts)
+	manager.MapClientStorage(cs)
+	manager.SetAuthorizeCodeTokenCfg(manage.DefaultAuthorizeCodeTokenCfg)
+	sc := &server.Config{
+		TokenType: "Bearer",
+		// Must follow the spec.
+		AllowGetAccessRequest: false,
+		// Support only the non-implicit flow.
+		AllowedResponseTypes: []oauth2.ResponseType{oauth2.Code},
+		// Allow:
+		// - Authorization Code (for first & third parties)
+		AllowedGrantTypes: []oauth2.GrantType{
+			oauth2.AuthorizationCode,
+		},
+		AllowedCodeChallengeMethods: []oauth2.CodeChallengeMethod{oauth2.CodeChallengePlain},
+	}
+
+	srv := server.NewServer(sc, manager)
+	srv.SetInternalErrorHandler(func(err error) *errors.Response {
+		log.Errorf("internal oauth error: %s", err)
+		return nil
+	})
+
+	srv.SetResponseErrorHandler(func(re *errors.Response) {
+		log.Errorf("internal response error: %s", re.Error)
+	})
+
+	m := &oauthModule{
+		oauthManager: manager,
+		oauthServer:  srv,
+		db:           db,
+		log:          log,
+	}
+
+	m.oauthServer.SetUserAuthorizationHandler(m.userAuthorizationHandler)
+	m.oauthServer.SetClientInfoHandler(server.ClientFormHandler)
+	return m
+}
+
+// Route satisfies the RESTAPIModule interface
+func (m *oauthModule) Route(s router.Router) error {
+	s.AttachHandler(http.MethodPost, appsPath, m.appsPOSTHandler)
+
+	s.AttachHandler(http.MethodGet, authSignInPath, m.signInGETHandler)
+	s.AttachHandler(http.MethodPost, authSignInPath, m.signInPOSTHandler)
+
+	s.AttachHandler(http.MethodPost, oauthTokenPath, m.tokenPOSTHandler)
+
+	s.AttachHandler(http.MethodGet, oauthAuthorizePath, m.authorizeGETHandler)
+	s.AttachHandler(http.MethodPost, oauthAuthorizePath, m.authorizePOSTHandler)
+
+	s.AttachMiddleware(m.oauthTokenMiddleware)
+
+	return nil
+}
+
+/*
+	MAIN HANDLERS -- serve these through a server/router
+*/
+
+// appsPOSTHandler should be served at https://example.org/api/v1/apps
+// It is equivalent to: https://docs.joinmastodon.org/methods/apps/
+func (m *oauthModule) appsPOSTHandler(c *gin.Context) {
+	l := m.log.WithField("func", "AppsPOSTHandler")
+	l.Trace("entering AppsPOSTHandler")
+
+	form := &mastotypes.ApplicationPOSTRequest{}
+	if err := c.ShouldBind(form); err != nil {
+		c.JSON(http.StatusUnprocessableEntity, gin.H{"error": err.Error()})
+		return
+	}
+
+	// permitted length for most fields
+	permittedLength := 64
+	// redirect can be a bit bigger because we probably need to encode data in the redirect uri
+	permittedRedirect := 256
+
+	// check lengths of fields before proceeding so the user can't spam huge entries into the database
+	if len(form.ClientName) > permittedLength {
+		c.JSON(http.StatusBadRequest, gin.H{"error": fmt.Sprintf("client_name must be less than %d bytes", permittedLength)})
+		return
+	}
+	if len(form.Website) > permittedLength {
+		c.JSON(http.StatusBadRequest, gin.H{"error": fmt.Sprintf("website must be less than %d bytes", permittedLength)})
+		return
+	}
+	if len(form.RedirectURIs) > permittedRedirect {
+		c.JSON(http.StatusBadRequest, gin.H{"error": fmt.Sprintf("redirect_uris must be less than %d bytes", permittedRedirect)})
+		return
+	}
+	if len(form.Scopes) > permittedLength {
+		c.JSON(http.StatusBadRequest, gin.H{"error": fmt.Sprintf("scopes must be less than %d bytes", permittedLength)})
+		return
+	}
+
+	// set default 'read' for scopes if it's not set, this follows the default of the mastodon api https://docs.joinmastodon.org/methods/apps/
+	var scopes string
+	if form.Scopes == "" {
+		scopes = "read"
+	} else {
+		scopes = form.Scopes
+	}
+
+	// generate new IDs for this application and its associated client
+	clientID := uuid.NewString()
+	clientSecret := uuid.NewString()
+	vapidKey := uuid.NewString()
+
+	// generate the application to put in the database
+	app := &gtsmodel.Application{
+		Name:         form.ClientName,
+		Website:      form.Website,
+		RedirectURI:  form.RedirectURIs,
+		ClientID:     clientID,
+		ClientSecret: clientSecret,
+		Scopes:       scopes,
+		VapidKey:     vapidKey,
+	}
+
+	// chuck it in the db
+	if err := m.db.Put(app); err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
+		return
+	}
+
+	// now we need to model an oauth client from the application that the oauth library can use
+	oc := &oauthClient{
+		ID:     clientID,
+		Secret: clientSecret,
+		Domain: form.RedirectURIs,
+		UserID: "", // This client isn't yet associated with a specific user,  it's just an app client right now
+	}
+
+	// chuck it in the db
+	if err := m.db.Put(oc); err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
+		return
+	}
+
+	// done, return the new app information per the spec here: https://docs.joinmastodon.org/methods/apps/
+	c.JSON(http.StatusOK, app.ToMastotype())
+}
+
+// signInGETHandler should be served at https://example.org/auth/sign_in.
+// The idea is to present a sign in page to the user, where they can enter their username and password.
+// The form will then POST to the sign in page, which will be handled by SignInPOSTHandler
+func (m *oauthModule) signInGETHandler(c *gin.Context) {
+	m.log.WithField("func", "SignInGETHandler").Trace("serving sign in html")
+	c.HTML(http.StatusOK, "sign-in.tmpl", gin.H{})
+}
+
+// signInPOSTHandler should be served at https://example.org/auth/sign_in.
+// The idea is to present a sign in page to the user, where they can enter their username and password.
+// The handler will then redirect to the auth handler served at /auth
+func (m *oauthModule) signInPOSTHandler(c *gin.Context) {
+	l := m.log.WithField("func", "SignInPOSTHandler")
+	s := sessions.Default(c)
+	form := &login{}
+	if err := c.ShouldBind(form); err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
+		return
+	}
+	l.Tracef("parsed form: %+v", form)
+
+	userid, err := m.validatePassword(form.Email, form.Password)
+	if err != nil {
+		c.String(http.StatusForbidden, err.Error())
+		return
+	}
+
+	s.Set("userid", userid)
+	if err := s.Save(); err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
+		return
+	}
+
+	l.Trace("redirecting to auth page")
+	c.Redirect(http.StatusFound, oauthAuthorizePath)
+}
+
+// tokenPOSTHandler should be served as a POST at https://example.org/oauth/token
+// The idea here is to serve an oauth access token to a user, which can be used for authorizing against non-public APIs.
+// See https://docs.joinmastodon.org/methods/apps/oauth/#obtain-a-token
+func (m *oauthModule) tokenPOSTHandler(c *gin.Context) {
+	l := m.log.WithField("func", "TokenPOSTHandler")
+	l.Trace("entered TokenPOSTHandler")
+	if err := m.oauthServer.HandleTokenRequest(c.Writer, c.Request); err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
+	}
+}
+
+// authorizeGETHandler should be served as GET at https://example.org/oauth/authorize
+// The idea here is to present an oauth authorize page to the user, with a button
+// that they have to click to accept. See here: https://docs.joinmastodon.org/methods/apps/oauth/#authorize-a-user
+func (m *oauthModule) authorizeGETHandler(c *gin.Context) {
+	l := m.log.WithField("func", "AuthorizeGETHandler")
+	s := sessions.Default(c)
+
+	// UserID will be set in the session by AuthorizePOSTHandler if the caller has already gone through the authentication flow
+	// If it's not set, then we don't know yet who the user is, so we need to redirect them to the sign in page.
+	userID, ok := s.Get("userid").(string)
+	if !ok || userID == "" {
+		l.Trace("userid was empty, parsing form then redirecting to sign in page")
+		if err := parseAuthForm(c, l); err != nil {
+			c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
+		} else {
+			c.Redirect(http.StatusFound, authSignInPath)
+		}
+		return
+	}
+
+	// We can use the client_id on the session to retrieve info about the app associated with the client_id
+	clientID, ok := s.Get("client_id").(string)
+	if !ok || clientID == "" {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": "no client_id found in session"})
+		return
+	}
+	app := &gtsmodel.Application{
+		ClientID: clientID,
+	}
+	if err := m.db.GetWhere("client_id", app.ClientID, app); err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": fmt.Sprintf("no application found for client id %s", clientID)})
+		return
+	}
+
+	// we can also use the userid of the user to fetch their username from the db to greet them nicely <3
+	user := &gtsmodel.User{
+		ID: userID,
+	}
+	if err := m.db.GetByID(user.ID, user); err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
+		return
+	}
+
+	acct := &gtsmodel.Account{
+		ID: user.AccountID,
+	}
+
+	if err := m.db.GetByID(acct.ID, acct); err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
+		return
+	}
+
+	// Finally we should also get the redirect and scope of this particular request, as stored in the session.
+	redirect, ok := s.Get("redirect_uri").(string)
+	if !ok || redirect == "" {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": "no redirect_uri found in session"})
+		return
+	}
+	scope, ok := s.Get("scope").(string)
+	if !ok || scope == "" {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": "no scope found in session"})
+		return
+	}
+
+	// the authorize template will display a form to the user where they can get some information
+	// about the app that's trying to authorize, and the scope of the request.
+	// They can then approve it if it looks OK to them, which will POST to the AuthorizePOSTHandler
+	l.Trace("serving authorize html")
+	c.HTML(http.StatusOK, "authorize.tmpl", gin.H{
+		"appname":    app.Name,
+		"appwebsite": app.Website,
+		"redirect":   redirect,
+		"scope":      scope,
+		"user":       acct.Username,
+	})
+}
+
+// authorizePOSTHandler should be served as POST at https://example.org/oauth/authorize
+// At this point we assume that the user has A) logged in and B) accepted that the app should act for them,
+// so we should proceed with the authentication flow and generate an oauth token for them if we can.
+// See here: https://docs.joinmastodon.org/methods/apps/oauth/#authorize-a-user
+func (m *oauthModule) authorizePOSTHandler(c *gin.Context) {
+	l := m.log.WithField("func", "AuthorizePOSTHandler")
+	s := sessions.Default(c)
+
+	// At this point we know the user has said 'yes' to allowing the application and oauth client
+	// work for them, so we can set the
+
+	// We need to retrieve the original form submitted to the authorizeGEThandler, and
+	// recreate it on the request so that it can be used further by the oauth2 library.
+	// So first fetch all the values from the session.
+	forceLogin, ok := s.Get("force_login").(string)
+	if !ok {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "session missing force_login"})
+		return
+	}
+	responseType, ok := s.Get("response_type").(string)
+	if !ok || responseType == "" {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "session missing response_type"})
+		return
+	}
+	clientID, ok := s.Get("client_id").(string)
+	if !ok || clientID == "" {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "session missing client_id"})
+		return
+	}
+	redirectURI, ok := s.Get("redirect_uri").(string)
+	if !ok || redirectURI == "" {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "session missing redirect_uri"})
+		return
+	}
+	scope, ok := s.Get("scope").(string)
+	if !ok {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "session missing scope"})
+		return
+	}
+	userID, ok := s.Get("userid").(string)
+	if !ok {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "session missing userid"})
+		return
+	}
+	// we're done with the session so we can clear it now
+	s.Clear()
+
+	// now set the values on the request
+	values := url.Values{}
+	values.Set("force_login", forceLogin)
+	values.Set("response_type", responseType)
+	values.Set("client_id", clientID)
+	values.Set("redirect_uri", redirectURI)
+	values.Set("scope", scope)
+	values.Set("userid", userID)
+	c.Request.Form = values
+	l.Tracef("values on request set to %+v", c.Request.Form)
+
+	// and proceed with authorization using the oauth2 library
+	if err := m.oauthServer.HandleAuthorizeRequest(c.Writer, c.Request); err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": err.Error()})
+	}
+}
+
+/*
+	MIDDLEWARE
+*/
+
+// oauthTokenMiddleware
+func (m *oauthModule) oauthTokenMiddleware(c *gin.Context) {
+	l := m.log.WithField("func", "ValidatePassword")
+	l.Trace("entering OauthTokenMiddleware")
+	if ti, err := m.oauthServer.ValidationBearerToken(c.Request); err == nil {
+		l.Tracef("authenticated user %s with bearer token, scope is %s", ti.GetUserID(), ti.GetScope())
+		c.Set("authenticated_user", ti.GetUserID())
+
+	} else {
+		l.Trace("continuing with unauthenticated request")
+	}
+}
+
+/*
+	SUB-HANDLERS -- don't serve these directly, they should be attached to the oauth2 server or used inside handler funcs
+*/
+
+// validatePassword takes an email address and a password.
+// The goal is to authenticate the password against the one for that email
+// address stored in the database. If OK, we return the userid (a uuid) for that user,
+// so that it can be used in further Oauth flows to generate a token/retreieve an oauth client from the db.
+func (m *oauthModule) validatePassword(email string, password string) (userid string, err error) {
+	l := m.log.WithField("func", "ValidatePassword")
+
+	// make sure an email/password was provided and bail if not
+	if email == "" || password == "" {
+		l.Debug("email or password was not provided")
+		return incorrectPassword()
+	}
+
+	// first we select the user from the database based on email address, bail if no user found for that email
+	gtsUser := &gtsmodel.User{}
+
+	if err := m.db.GetWhere("email", email, gtsUser); err != nil {
+		l.Debugf("user %s was not retrievable from db during oauth authorization attempt: %s", email, err)
+		return incorrectPassword()
+	}
+
+	// make sure a password is actually set and bail if not
+	if gtsUser.EncryptedPassword == "" {
+		l.Warnf("encrypted password for user %s was empty for some reason", gtsUser.Email)
+		return incorrectPassword()
+	}
+
+	// compare the provided password with the encrypted one from the db, bail if they don't match
+	if err := bcrypt.CompareHashAndPassword([]byte(gtsUser.EncryptedPassword), []byte(password)); err != nil {
+		l.Debugf("password hash didn't match for user %s during login attempt: %s", gtsUser.Email, err)
+		return incorrectPassword()
+	}
+
+	// If we've made it this far the email/password is correct, so we can just return the id of the user.
+	userid = gtsUser.ID
+	l.Tracef("returning (%s, %s)", userid, err)
+	return
+}
+
+// incorrectPassword is just a little helper function to use in the ValidatePassword function
+func incorrectPassword() (string, error) {
+	return "", errors.New("password/email combination was incorrect")
+}
+
+// userAuthorizationHandler gets the user's ID from the 'userid' field of the request form,
+// or redirects to the /auth/sign_in page, if this key is not present.
+func (m *oauthModule) userAuthorizationHandler(w http.ResponseWriter, r *http.Request) (userID string, err error) {
+	l := m.log.WithField("func", "UserAuthorizationHandler")
+	userID = r.FormValue("userid")
+	if userID == "" {
+		return "", errors.New("userid was empty, redirecting to sign in page")
+	}
+	l.Tracef("returning userID %s", userID)
+	return userID, err
+}
+
+// parseAuthForm parses the OAuthAuthorize form in the gin context, and stores
+// the values in the form into the session.
+func parseAuthForm(c *gin.Context, l *logrus.Entry) error {
+	s := sessions.Default(c)
+
+	// first make sure they've filled out the authorize form with the required values
+	form := &mastotypes.OAuthAuthorize{}
+	if err := c.ShouldBind(form); err != nil {
+		return err
+	}
+	l.Tracef("parsed form: %+v", form)
+
+	// these fields are *required* so check 'em
+	if form.ResponseType == "" || form.ClientID == "" || form.RedirectURI == "" {
+		return errors.New("missing one of: response_type, client_id or redirect_uri")
+	}
+
+	// set default scope to read
+	if form.Scope == "" {
+		form.Scope = "read"
+	}
+
+	// save these values from the form so we can use them elsewhere in the session
+	s.Set("force_login", form.ForceLogin)
+	s.Set("response_type", form.ResponseType)
+	s.Set("client_id", form.ClientID)
+	s.Set("redirect_uri", form.RedirectURI)
+	s.Set("scope", form.Scope)
+	return s.Save()
+}