Remember parameters on registration (#2225)

* Remember parameters for sessions
Cleanup sessions on successfully registering or after a while

* Add flakey test

* Update to use time.AfterFunc, add more tests

* Try to drain the channel, if possible

5 files changed, 141 insertions, 26 deletions

diff --git a/clientapi/routing/auth_fallback.go b/clientapi/routing/auth_fallback.go
index 839ca9e5..abfe830f 100644
--- a/clientapi/routing/auth_fallback.go
+++ b/clientapi/routing/auth_fallback.go
@@ -162,7 +162,7 @@ func AuthFallback(
 			}
 
 			// Success. Add recaptcha as a completed login flow
-			AddCompletedSessionStage(sessionID, authtypes.LoginTypeRecaptcha)
+			sessions.addCompletedSessionStage(sessionID, authtypes.LoginTypeRecaptcha)
 
 			serveSuccess()
 			return nil
diff --git a/clientapi/routing/key_crosssigning.go b/clientapi/routing/key_crosssigning.go
index 7ecab9d4..4426b7fd 100644
--- a/clientapi/routing/key_crosssigning.go
+++ b/clientapi/routing/key_crosssigning.go
@@ -70,7 +70,7 @@ func UploadCrossSigningDeviceKeys(
 	if _, authErr := typePassword.Login(req.Context(), &uploadReq.Auth.PasswordRequest); authErr != nil {
 		return *authErr
 	}
-	AddCompletedSessionStage(sessionID, authtypes.LoginTypePassword)
+	sessions.addCompletedSessionStage(sessionID, authtypes.LoginTypePassword)
 
 	uploadReq.UserID = device.UserID
 	keyserverAPI.PerformUploadDeviceKeys(req.Context(), &uploadReq.PerformUploadDeviceKeysRequest, uploadRes)
diff --git a/clientapi/routing/password.go b/clientapi/routing/password.go
index 49951019..acac60fa 100644
--- a/clientapi/routing/password.go
+++ b/clientapi/routing/password.go
@@ -74,7 +74,7 @@ func Password(
 	if _, authErr := typePassword.Login(req.Context(), &r.Auth.PasswordRequest); authErr != nil {
 		return *authErr
 	}
-	AddCompletedSessionStage(sessionID, authtypes.LoginTypePassword)
+	sessions.addCompletedSessionStage(sessionID, authtypes.LoginTypePassword)
 
 	// Check the new password strength.
 	if resErr = validatePassword(r.NewPassword); resErr != nil {
diff --git a/clientapi/routing/register.go b/clientapi/routing/register.go
index d00d9886..10cfa432 100644
--- a/clientapi/routing/register.go
+++ b/clientapi/routing/register.go
@@ -72,14 +72,19 @@ func init() {
 // sessionsDict keeps track of completed auth stages for each session.
 // It shouldn't be passed by value because it contains a mutex.
 type sessionsDict struct {
-	sync.Mutex
+	sync.RWMutex
 	sessions map[string][]authtypes.LoginType
+	params   map[string]registerRequest
+	timer    map[string]*time.Timer
 }
 
-// GetCompletedStages returns the completed stages for a session.
-func (d *sessionsDict) GetCompletedStages(sessionID string) []authtypes.LoginType {
-	d.Lock()
-	defer d.Unlock()
+// defaultTimeout is the timeout used to clean up sessions
+const defaultTimeOut = time.Minute * 5
+
+// getCompletedStages returns the completed stages for a session.
+func (d *sessionsDict) getCompletedStages(sessionID string) []authtypes.LoginType {
+	d.RLock()
+	defer d.RUnlock()
 
 	if completedStages, ok := d.sessions[sessionID]; ok {
 		return completedStages
@@ -88,28 +93,79 @@ func (d *sessionsDict) GetCompletedStages(sessionID string) []authtypes.LoginTyp
 	return make([]authtypes.LoginType, 0)
 }
 
+// addParams adds a registerRequest to a sessionID and starts a timer to delete that registerRequest
+func (d *sessionsDict) addParams(sessionID string, r registerRequest) {
+	d.startTimer(defaultTimeOut, sessionID)
+	d.Lock()
+	defer d.Unlock()
+	d.params[sessionID] = r
+}
+
+func (d *sessionsDict) getParams(sessionID string) (registerRequest, bool) {
+	d.RLock()
+	defer d.RUnlock()
+	r, ok := d.params[sessionID]
+	return r, ok
+}
+
+// deleteSession cleans up a given session, either because the registration completed
+// successfully, or because a given timeout (default: 5min) was reached.
+func (d *sessionsDict) deleteSession(sessionID string) {
+	d.Lock()
+	defer d.Unlock()
+	delete(d.params, sessionID)
+	delete(d.sessions, sessionID)
+	// stop the timer, e.g. because the registration was completed
+	if t, ok := d.timer[sessionID]; ok {
+		if !t.Stop() {
+			select {
+			case <-t.C:
+			default:
+			}
+		}
+		delete(d.timer, sessionID)
+	}
+}
+
 func newSessionsDict() *sessionsDict {
 	return &sessionsDict{
 		sessions: make(map[string][]authtypes.LoginType),
+		params:   make(map[string]registerRequest),
+		timer:    make(map[string]*time.Timer),
 	}
 }
 
-// AddCompletedSessionStage records that a session has completed an auth stage.
-func AddCompletedSessionStage(sessionID string, stage authtypes.LoginType) {
-	sessions.Lock()
-	defer sessions.Unlock()
+func (d *sessionsDict) startTimer(duration time.Duration, sessionID string) {
+	d.Lock()
+	defer d.Unlock()
+	t, ok := d.timer[sessionID]
+	if ok {
+		if !t.Stop() {
+			<-t.C
+		}
+		t.Reset(duration)
+		return
+	}
+	d.timer[sessionID] = time.AfterFunc(duration, func() {
+		d.deleteSession(sessionID)
+	})
+}
 
-	for _, completedStage := range sessions.sessions[sessionID] {
+// addCompletedSessionStage records that a session has completed an auth stage
+// also starts a timer to delete the session once done.
+func (d *sessionsDict) addCompletedSessionStage(sessionID string, stage authtypes.LoginType) {
+	d.startTimer(defaultTimeOut, sessionID)
+	d.Lock()
+	defer d.Unlock()
+	for _, completedStage := range d.sessions[sessionID] {
 		if completedStage == stage {
 			return
 		}
 	}
-	sessions.sessions[sessionID] = append(sessions.sessions[sessionID], stage)
+	d.sessions[sessionID] = append(sessions.sessions[sessionID], stage)
 }
 
 var (
-	// TODO: Remove old sessions. Need to do so on a session-specific timeout.
-	// sessions stores the completed flow stages for all sessions. Referenced using their sessionID.
 	sessions           = newSessionsDict()
 	validUsernameRegex = regexp.MustCompile(`^[0-9a-z_\-=./]+$`)
 )
@@ -167,7 +223,7 @@ func newUserInteractiveResponse(
 	params map[string]interface{},
 ) userInteractiveResponse {
 	return userInteractiveResponse{
-		fs, sessions.GetCompletedStages(sessionID), params, sessionID,
+		fs, sessions.getCompletedStages(sessionID), params, sessionID,
 	}
 }
 
@@ -645,12 +701,12 @@ func handleRegistrationFlow(
 		}
 
 		// Add Recaptcha to the list of completed registration stages
-		AddCompletedSessionStage(sessionID, authtypes.LoginTypeRecaptcha)
+		sessions.addCompletedSessionStage(sessionID, authtypes.LoginTypeRecaptcha)
 
 	case authtypes.LoginTypeDummy:
 		// there is nothing to do
 		// Add Dummy to the list of completed registration stages
-		AddCompletedSessionStage(sessionID, authtypes.LoginTypeDummy)
+		sessions.addCompletedSessionStage(sessionID, authtypes.LoginTypeDummy)
 
 	case "":
 		// An empty auth type means that we want to fetch the available
@@ -666,7 +722,7 @@ func handleRegistrationFlow(
 	// Check if the user's registration flow has been completed successfully
 	// A response with current registration flow and remaining available methods
 	// will be returned if a flow has not been successfully completed yet
-	return checkAndCompleteFlow(sessions.GetCompletedStages(sessionID),
+	return checkAndCompleteFlow(sessions.getCompletedStages(sessionID),
 		req, r, sessionID, cfg, userAPI)
 }
 
@@ -708,7 +764,7 @@ func handleApplicationServiceRegistration(
 	// Don't need to worry about appending to registration stages as
 	// application service registration is entirely separate.
 	return completeRegistration(
-		req.Context(), userAPI, r.Username, "", appserviceID, req.RemoteAddr, req.UserAgent(),
+		req.Context(), userAPI, r.Username, "", appserviceID, req.RemoteAddr, req.UserAgent(), r.Auth.Session,
 		r.InhibitLogin, r.InitialDisplayName, r.DeviceID, userapi.AccountTypeAppService,
 	)
 }
@@ -727,11 +783,11 @@ func checkAndCompleteFlow(
 	if checkFlowCompleted(flow, cfg.Derived.Registration.Flows) {
 		// This flow was completed, registration can continue
 		return completeRegistration(
-			req.Context(), userAPI, r.Username, r.Password, "", req.RemoteAddr, req.UserAgent(),
+			req.Context(), userAPI, r.Username, r.Password, "", req.RemoteAddr, req.UserAgent(), sessionID,
 			r.InhibitLogin, r.InitialDisplayName, r.DeviceID, userapi.AccountTypeUser,
 		)
 	}
-
+	sessions.addParams(sessionID, r)
 	// There are still more stages to complete.
 	// Return the flows and those that have been completed.
 	return util.JSONResponse{
@@ -750,11 +806,25 @@ func checkAndCompleteFlow(
 func completeRegistration(
 	ctx context.Context,
 	userAPI userapi.UserInternalAPI,
-	username, password, appserviceID, ipAddr, userAgent string,
+	username, password, appserviceID, ipAddr, userAgent, sessionID string,
 	inhibitLogin eventutil.WeakBoolean,
 	displayName, deviceID *string,
 	accType userapi.AccountType,
 ) util.JSONResponse {
+	var registrationOK bool
+	defer func() {
+		if registrationOK {
+			sessions.deleteSession(sessionID)
+		}
+	}()
+
+	if data, ok := sessions.getParams(sessionID); ok {
+		username = data.Username
+		password = data.Password
+		deviceID = data.DeviceID
+		displayName = data.InitialDisplayName
+		inhibitLogin = data.InhibitLogin
+	}
 	if username == "" {
 		return util.JSONResponse{
 			Code: http.StatusBadRequest,
@@ -795,6 +865,7 @@ func completeRegistration(
 	// Check whether inhibit_login option is set. If so, don't create an access
 	// token or a device for this user
 	if inhibitLogin {
+		registrationOK = true
 		return util.JSONResponse{
 			Code: http.StatusOK,
 			JSON: registerResponse{
@@ -828,6 +899,7 @@ func completeRegistration(
 		}
 	}
 
+	registrationOK = true
 	return util.JSONResponse{
 		Code: http.StatusOK,
 		JSON: registerResponse{
@@ -976,5 +1048,5 @@ func handleSharedSecretRegistration(userAPI userapi.UserInternalAPI, sr *SharedS
 	if ssrr.Admin {
 		accType = userapi.AccountTypeAdmin
 	}
-	return completeRegistration(req.Context(), userAPI, ssrr.User, ssrr.Password, "", req.RemoteAddr, req.UserAgent(), false, &ssrr.User, &deviceID, accType)
+	return completeRegistration(req.Context(), userAPI, ssrr.User, ssrr.Password, "", req.RemoteAddr, req.UserAgent(), "", false, &ssrr.User, &deviceID, accType)
 }
diff --git a/clientapi/routing/register_test.go b/clientapi/routing/register_test.go
index 1f615dc2..c6b7e61c 100644
--- a/clientapi/routing/register_test.go
+++ b/clientapi/routing/register_test.go
@@ -17,6 +17,7 @@ package routing
 import (
 	"regexp"
 	"testing"
+	"time"
 
 	"github.com/matrix-org/dendrite/clientapi/auth/authtypes"
 	"github.com/matrix-org/dendrite/setup/config"
@@ -140,7 +141,7 @@ func TestFlowCheckingExtraneousIncorrectInput(t *testing.T) {
 func TestEmptyCompletedFlows(t *testing.T) {
 	fakeEmptySessions := newSessionsDict()
 	fakeSessionID := "aRandomSessionIDWhichDoesNotExist"
-	ret := fakeEmptySessions.GetCompletedStages(fakeSessionID)
+	ret := fakeEmptySessions.getCompletedStages(fakeSessionID)
 
 	// check for []
 	if ret == nil || len(ret) != 0 {
@@ -208,3 +209,45 @@ func TestValidationOfApplicationServices(t *testing.T) {
 		t.Errorf("user_id should not have been valid: @_something_else:localhost")
 	}
 }
+
+func TestSessionCleanUp(t *testing.T) {
+	s := newSessionsDict()
+
+	t.Run("session is cleaned up after a while", func(t *testing.T) {
+		t.Parallel()
+		dummySession := "helloWorld"
+		// manually added, as s.addParams() would start the timer with the default timeout
+		s.params[dummySession] = registerRequest{Username: "Testing"}
+		s.startTimer(time.Millisecond, dummySession)
+		time.Sleep(time.Millisecond * 2)
+		if data, ok := s.getParams(dummySession); ok {
+			t.Errorf("expected session to be deleted: %+v", data)
+		}
+	})
+
+	t.Run("session is deleted, once the registration completed", func(t *testing.T) {
+		t.Parallel()
+		dummySession := "helloWorld2"
+		s.startTimer(time.Minute, dummySession)
+		s.deleteSession(dummySession)
+		if data, ok := s.getParams(dummySession); ok {
+			t.Errorf("expected session to be deleted: %+v", data)
+		}
+	})
+
+	t.Run("session timer is restarted after second call", func(t *testing.T) {
+		t.Parallel()
+		dummySession := "helloWorld3"
+		// the following will start a timer with the default timeout of 5min
+		s.addParams(dummySession, registerRequest{Username: "Testing"})
+		s.addCompletedSessionStage(dummySession, authtypes.LoginTypeRecaptcha)
+		s.addCompletedSessionStage(dummySession, authtypes.LoginTypeDummy)
+		s.getCompletedStages(dummySession)
+		// reset the timer with a lower timeout
+		s.startTimer(time.Millisecond, dummySession)
+		time.Sleep(time.Millisecond * 2)
+		if data, ok := s.getParams(dummySession); ok {
+			t.Errorf("expected session to be deleted: %+v", data)
+		}
+	})
+}
\ No newline at end of file