Some more messing around with oauth2

internal/oauth/oauth.go

@@ -19,7 +19,14 @@
 package oauth
 
 import (
+	"bytes"
+	"net/http"
+	"net/url"
+	"time"
+
+	"github.com/gin-gonic/gin"
 	"github.com/go-pg/pg/v10"
+	"github.com/go-session/session"
 	"github.com/gotosocial/gotosocial/internal/api"
 	"github.com/gotosocial/gotosocial/internal/gtsmodel"
 	"github.com/gotosocial/oauth2/v4"
@@ -30,6 +37,8 @@ import (
 	"golang.org/x/crypto/bcrypt"
 )
 
+const methodAny = "ANY"
+
 type API struct {
 	manager *manage.Manager
 	server  *server.Server
@@ -52,15 +61,24 @@ func New(ts oauth2.TokenStore, cs oauth2.ClientStore, conn *pg.DB, log *logrus.L
 		log.Errorf("internal response error: %s", re.Error)
 	})
 
-	return &API{
+	api := &API{
 		manager: manager,
 		server:  srv,
 		conn:    conn,
 		log:     log,
 	}
+
+	api.server.SetPasswordAuthorizationHandler(api.PasswordAuthorizationHandler)
+	api.server.SetUserAuthorizationHandler(api.UserAuthorizationHandler)
+	api.server.SetClientInfoHandler(server.ClientFormHandler)
+	return api
 }
 
 func (a *API) AddRoutes(s api.Server) error {
+	s.AttachHandler(methodAny, "/auth/sign_in", gin.WrapF(a.SignInHandler))
+	s.AttachHandler(methodAny, "/oauth/token", gin.WrapF(a.TokenHandler))
+	s.AttachHandler(methodAny, "/oauth/authorize", gin.WrapF(a.AuthorizeHandler))
+	s.AttachHandler(methodAny, "/auth", gin.WrapF(a.AuthHandler))
 	return nil
 }
 
@@ -68,7 +86,101 @@ func incorrectPassword() (string, error) {
 	return "", errors.New("password/email combination was incorrect")
 }
 
+/*
+	MAIN HANDLERS -- serve these through a server/router
+*/
+
+// SignInHandler 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 (a *API) SignInHandler(w http.ResponseWriter, r *http.Request) {
+	store, err := session.Start(r.Context(), w, r)
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	if r.Method == "POST" {
+		if r.Form == nil {
+			if err := r.ParseForm(); err != nil {
+				http.Error(w, err.Error(), http.StatusInternalServerError)
+				return
+			}
+		}
+		store.Set("username", r.Form.Get("username"))
+		store.Save()
+
+		w.Header().Set("Location", "/auth")
+		w.WriteHeader(http.StatusFound)
+		return
+	}
+	http.ServeContent(w, r, "sign_in.html", time.Unix(0, 0), bytes.NewReader([]byte(signInHTML)))
+}
+
+// TokenHandler should be served 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 (a *API) TokenHandler(w http.ResponseWriter, r *http.Request) {
+	if err := a.server.HandleTokenRequest(w, r); err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+	}
+}
+
+// AuthorizeHandler should be served 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 (a *API) AuthorizeHandler(w http.ResponseWriter, r *http.Request) {
+	store, err := session.Start(nil, w, r)
+	if err != nil {
+
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	if _, ok := store.Get("username"); !ok {
+		w.Header().Set("Location", "/auth/sign_in")
+		w.WriteHeader(http.StatusFound)
+		return
+	}
+
+	http.ServeContent(w, r, "authorize.html", time.Unix(0, 0), bytes.NewReader([]byte(authorizeHTML)))
+}
+
+// AuthHandler should be served at https://example.org/auth
+func (a *API) AuthHandler(w http.ResponseWriter, r *http.Request) {
+	store, err := session.Start(r.Context(), w, r)
+	if err != nil {
+		a.log.Errorf("error creating session in authhandler: %s", err)
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	var form url.Values
+	if v, ok := store.Get("ReturnUri"); ok {
+		form = v.(url.Values)
+	}
+	r.Form = form
+
+	store.Delete("ReturnUri")
+	store.Save()
+
+	if err := a.server.HandleAuthorizeRequest(w, r); err != nil {
+		a.log.Errorf("error in authhandler during handleauthorizerequest: %s", err)
+		http.Error(w, err.Error(), http.StatusBadRequest)
+	}
+}
+
+/*
+	SUB-HANDLERS -- don't serve these directly
+*/
+
+// PasswordAuthorizationHandler takes a username (in this case, we use 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 (a *API) PasswordAuthorizationHandler(email string, password string) (userid string, err error) {
+	a.log.Debugf("entering password authorization handler with email: %s and password: %s", email, password)
+
 	// 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 := a.conn.Model(gtsUser).Where("email = ?", email).Select(); err != nil {
@@ -93,3 +205,35 @@ func (a *API) PasswordAuthorizationHandler(email string, password string) (useri
 	userid = gtsUser.ID
 	return
 }
+
+// UserAuthorizationHandler gets the user's email address from the session key 'username'
+// or redirects to the /auth/sign_in page, if this key is not present.
+func (a *API) UserAuthorizationHandler(w http.ResponseWriter, r *http.Request) (string, error) {
+
+	a.log.Errorf("entering userauthorizationhandler")
+
+	sessionStore, err := session.Start(r.Context(), w, r)
+	if err != nil {
+		a.log.Errorf("error starting session: %s", err)
+		return "", err
+	}
+
+	v, ok := sessionStore.Get("username")
+	if !ok {
+		if err := r.ParseForm(); err != nil {
+			a.log.Errorf("error parsing form: %s", err)
+			return "", err
+		}
+
+		sessionStore.Set("ReturnUri", r.Form)
+		sessionStore.Save()
+
+		w.Header().Set("Location", "/auth/sign_in")
+		w.WriteHeader(http.StatusFound)
+		return v.(string), nil
+	}
+
+	sessionStore.Delete("username")
+	sessionStore.Save()
+	return v.(string), nil
+}