1 files changed, 335 insertions, 0 deletions
diff --git a/internal/api/auth/authorize.go b/internal/api/auth/authorize.go
new file mode 100644
index 000000000..e504f6be2
--- /dev/null
+++ b/internal/api/auth/authorize.go
@@ -0,0 +1,335 @@
+/*
+   GoToSocial
+   Copyright (C) 2021-2022 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 auth
+
+import (
+	"errors"
+	"fmt"
+	"net/http"
+	"net/url"
+
+	"github.com/gin-contrib/sessions"
+	"github.com/gin-gonic/gin"
+	"github.com/google/uuid"
+	apimodel "github.com/superseriousbusiness/gotosocial/internal/api/model"
+	apiutil "github.com/superseriousbusiness/gotosocial/internal/api/util"
+	"github.com/superseriousbusiness/gotosocial/internal/config"
+	"github.com/superseriousbusiness/gotosocial/internal/db"
+	"github.com/superseriousbusiness/gotosocial/internal/gtserror"
+	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
+	"github.com/superseriousbusiness/gotosocial/internal/oauth"
+)
+
+// 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.
+func (m *Module) AuthorizeGETHandler(c *gin.Context) {
+	s := sessions.Default(c)
+
+	if _, err := apiutil.NegotiateAccept(c, apiutil.HTMLAcceptHeaders...); err != nil {
+		apiutil.ErrorHandler(c, gtserror.NewErrorNotAcceptable(err, err.Error()), m.processor.InstanceGet)
+		return
+	}
+
+	// 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(sessionUserID).(string)
+	if !ok || userID == "" {
+		form := &apimodel.OAuthAuthorize{}
+		if err := c.ShouldBind(form); err != nil {
+			m.clearSession(s)
+			apiutil.ErrorHandler(c, gtserror.NewErrorBadRequest(err, oauth.HelpfulAdvice), m.processor.InstanceGet)
+			return
+		}
+
+		if errWithCode := saveAuthFormToSession(s, form); errWithCode != nil {
+			m.clearSession(s)
+			apiutil.ErrorHandler(c, errWithCode, m.processor.InstanceGet)
+			return
+		}
+
+		c.Redirect(http.StatusSeeOther, "/auth"+AuthSignInPath)
+		return
+	}
+
+	// use session information to validate app, user, and account for this request
+	clientID, ok := s.Get(sessionClientID).(string)
+	if !ok || clientID == "" {
+		m.clearSession(s)
+		err := fmt.Errorf("key %s was not found in session", sessionClientID)
+		apiutil.ErrorHandler(c, gtserror.NewErrorBadRequest(err, oauth.HelpfulAdvice), m.processor.InstanceGet)
+		return
+	}
+
+	app := &gtsmodel.Application{}
+	if err := m.db.GetWhere(c.Request.Context(), []db.Where{{Key: sessionClientID, Value: clientID}}, app); err != nil {
+		m.clearSession(s)
+		safe := fmt.Sprintf("application for %s %s could not be retrieved", sessionClientID, clientID)
+		var errWithCode gtserror.WithCode
+		if err == db.ErrNoEntries {
+			errWithCode = gtserror.NewErrorBadRequest(err, safe, oauth.HelpfulAdvice)
+		} else {
+			errWithCode = gtserror.NewErrorInternalError(err, safe, oauth.HelpfulAdvice)
+		}
+		apiutil.ErrorHandler(c, errWithCode, m.processor.InstanceGet)
+		return
+	}
+
+	user, err := m.db.GetUserByID(c.Request.Context(), userID)
+	if err != nil {
+		m.clearSession(s)
+		safe := fmt.Sprintf("user with id %s could not be retrieved", userID)
+		var errWithCode gtserror.WithCode
+		if err == db.ErrNoEntries {
+			errWithCode = gtserror.NewErrorBadRequest(err, safe, oauth.HelpfulAdvice)
+		} else {
+			errWithCode = gtserror.NewErrorInternalError(err, safe, oauth.HelpfulAdvice)
+		}
+		apiutil.ErrorHandler(c, errWithCode, m.processor.InstanceGet)
+		return
+	}
+
+	acct, err := m.db.GetAccountByID(c.Request.Context(), user.AccountID)
+	if err != nil {
+		m.clearSession(s)
+		safe := fmt.Sprintf("account with id %s could not be retrieved", user.AccountID)
+		var errWithCode gtserror.WithCode
+		if err == db.ErrNoEntries {
+			errWithCode = gtserror.NewErrorBadRequest(err, safe, oauth.HelpfulAdvice)
+		} else {
+			errWithCode = gtserror.NewErrorInternalError(err, safe, oauth.HelpfulAdvice)
+		}
+		apiutil.ErrorHandler(c, errWithCode, m.processor.InstanceGet)
+		return
+	}
+
+	if ensureUserIsAuthorizedOrRedirect(c, user, acct) {
+		return
+	}
+
+	// Finally we should also get the redirect and scope of this particular request, as stored in the session.
+	redirect, ok := s.Get(sessionRedirectURI).(string)
+	if !ok || redirect == "" {
+		m.clearSession(s)
+		err := fmt.Errorf("key %s was not found in session", sessionRedirectURI)
+		apiutil.ErrorHandler(c, gtserror.NewErrorBadRequest(err, oauth.HelpfulAdvice), m.processor.InstanceGet)
+		return
+	}
+
+	scope, ok := s.Get(sessionScope).(string)
+	if !ok || scope == "" {
+		m.clearSession(s)
+		err := fmt.Errorf("key %s was not found in session", sessionScope)
+		apiutil.ErrorHandler(c, gtserror.NewErrorBadRequest(err, oauth.HelpfulAdvice), m.processor.InstanceGet)
+		return
+	}
+
+	instance, errWithCode := m.processor.InstanceGet(c.Request.Context(), config.GetHost())
+	if errWithCode != nil {
+		apiutil.ErrorHandler(c, errWithCode, m.processor.InstanceGet)
+		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
+	c.HTML(http.StatusOK, "authorize.tmpl", gin.H{
+		"appname":    app.Name,
+		"appwebsite": app.Website,
+		"redirect":   redirect,
+		"scope":      scope,
+		"user":       acct.Username,
+		"instance":   instance,
+	})
+}
+
+// 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.
+func (m *Module) AuthorizePOSTHandler(c *gin.Context) {
+	s := sessions.Default(c)
+
+	// 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.
+	errs := []string{}
+
+	forceLogin, ok := s.Get(sessionForceLogin).(string)
+	if !ok {
+		forceLogin = "false"
+	}
+
+	responseType, ok := s.Get(sessionResponseType).(string)
+	if !ok || responseType == "" {
+		errs = append(errs, fmt.Sprintf("key %s was not found in session", sessionResponseType))
+	}
+
+	clientID, ok := s.Get(sessionClientID).(string)
+	if !ok || clientID == "" {
+		errs = append(errs, fmt.Sprintf("key %s was not found in session", sessionClientID))
+	}
+
+	redirectURI, ok := s.Get(sessionRedirectURI).(string)
+	if !ok || redirectURI == "" {
+		errs = append(errs, fmt.Sprintf("key %s was not found in session", sessionRedirectURI))
+	}
+
+	scope, ok := s.Get(sessionScope).(string)
+	if !ok {
+		errs = append(errs, fmt.Sprintf("key %s was not found in session", sessionScope))
+	}
+
+	var clientState string
+	if s, ok := s.Get(sessionClientState).(string); ok {
+		clientState = s
+	}
+
+	userID, ok := s.Get(sessionUserID).(string)
+	if !ok {
+		errs = append(errs, fmt.Sprintf("key %s was not found in session", sessionUserID))
+	}
+
+	if len(errs) != 0 {
+		errs = append(errs, oauth.HelpfulAdvice)
+		apiutil.ErrorHandler(c, gtserror.NewErrorBadRequest(errors.New("one or more missing keys on session during AuthorizePOSTHandler"), errs...), m.processor.InstanceGet)
+		return
+	}
+
+	user, err := m.db.GetUserByID(c.Request.Context(), userID)
+	if err != nil {
+		m.clearSession(s)
+		safe := fmt.Sprintf("user with id %s could not be retrieved", userID)
+		var errWithCode gtserror.WithCode
+		if err == db.ErrNoEntries {
+			errWithCode = gtserror.NewErrorBadRequest(err, safe, oauth.HelpfulAdvice)
+		} else {
+			errWithCode = gtserror.NewErrorInternalError(err, safe, oauth.HelpfulAdvice)
+		}
+		apiutil.ErrorHandler(c, errWithCode, m.processor.InstanceGet)
+		return
+	}
+
+	acct, err := m.db.GetAccountByID(c.Request.Context(), user.AccountID)
+	if err != nil {
+		m.clearSession(s)
+		safe := fmt.Sprintf("account with id %s could not be retrieved", user.AccountID)
+		var errWithCode gtserror.WithCode
+		if err == db.ErrNoEntries {
+			errWithCode = gtserror.NewErrorBadRequest(err, safe, oauth.HelpfulAdvice)
+		} else {
+			errWithCode = gtserror.NewErrorInternalError(err, safe, oauth.HelpfulAdvice)
+		}
+		apiutil.ErrorHandler(c, errWithCode, m.processor.InstanceGet)
+		return
+	}
+
+	if ensureUserIsAuthorizedOrRedirect(c, user, acct) {
+		return
+	}
+
+	if redirectURI != oauth.OOBURI {
+		// we're done with the session now, so just clear it out
+		m.clearSession(s)
+	}
+
+	// we have to set the values on the request form
+	// so that they're picked up by the oauth server
+	c.Request.Form = url.Values{
+		sessionForceLogin:   {forceLogin},
+		sessionResponseType: {responseType},
+		sessionClientID:     {clientID},
+		sessionRedirectURI:  {redirectURI},
+		sessionScope:        {scope},
+		sessionUserID:       {userID},
+	}
+
+	if clientState != "" {
+		c.Request.Form.Set("state", clientState)
+	}
+
+	if errWithCode := m.processor.OAuthHandleAuthorizeRequest(c.Writer, c.Request); errWithCode != nil {
+		apiutil.ErrorHandler(c, errWithCode, m.processor.InstanceGet)
+	}
+}
+
+// saveAuthFormToSession checks the given OAuthAuthorize form,
+// and stores the values in the form into the session.
+func saveAuthFormToSession(s sessions.Session, form *apimodel.OAuthAuthorize) gtserror.WithCode {
+	if form == nil {
+		err := errors.New("OAuthAuthorize form was nil")
+		return gtserror.NewErrorBadRequest(err, err.Error(), oauth.HelpfulAdvice)
+	}
+
+	if form.ResponseType == "" {
+		err := errors.New("field response_type was not set on OAuthAuthorize form")
+		return gtserror.NewErrorBadRequest(err, err.Error(), oauth.HelpfulAdvice)
+	}
+
+	if form.ClientID == "" {
+		err := errors.New("field client_id was not set on OAuthAuthorize form")
+		return gtserror.NewErrorBadRequest(err, err.Error(), oauth.HelpfulAdvice)
+	}
+
+	if form.RedirectURI == "" {
+		err := errors.New("field redirect_uri was not set on OAuthAuthorize form")
+		return gtserror.NewErrorBadRequest(err, err.Error(), oauth.HelpfulAdvice)
+	}
+
+	// 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(sessionForceLogin, form.ForceLogin)
+	s.Set(sessionResponseType, form.ResponseType)
+	s.Set(sessionClientID, form.ClientID)
+	s.Set(sessionRedirectURI, form.RedirectURI)
+	s.Set(sessionScope, form.Scope)
+	s.Set(sessionInternalState, uuid.NewString())
+	s.Set(sessionClientState, form.State)
+
+	if err := s.Save(); err != nil {
+		err := fmt.Errorf("error saving form values onto session: %s", err)
+		return gtserror.NewErrorInternalError(err, oauth.HelpfulAdvice)
+	}
+
+	return nil
+}
+
+func ensureUserIsAuthorizedOrRedirect(ctx *gin.Context, user *gtsmodel.User, account *gtsmodel.Account) (redirected bool) {
+	if user.ConfirmedAt.IsZero() {
+		ctx.Redirect(http.StatusSeeOther, "/auth"+AuthCheckYourEmailPath)
+		redirected = true
+		return
+	}
+
+	if !*user.Approved {
+		ctx.Redirect(http.StatusSeeOther, "/auth"+AuthWaitForApprovalPath)
+		redirected = true
+		return
+	}
+
+	if *user.Disabled || !account.SuspendedAt.IsZero() {
+		ctx.Redirect(http.StatusSeeOther, "/auth"+AuthAccountDisabledPath)
+		redirected = true
+		return
+	}
+
+	return
+}