EnableRateVisitor flag

server/config.go

@@ -133,6 +133,7 @@ type Config struct {
 	EnableSignup                         bool // Enable creation of accounts via API and UI
 	EnableLogin                          bool
 	EnableReservations                   bool   // Allow users with role "user" to own/reserve topics
+	EnableRateVisitor                    bool   // Enable subscriber-based rate limiting for UnifiedPush topics
 	AccessControlAllowOrigin             string // CORS header field to restrict access from web clients
 	Version                              string // injected by App
 }

server/server.go

@@ -597,7 +597,7 @@ func (s *Server) handlePublishWithoutResponse(r *http.Request, v *visitor) (*mes
 	if e != nil {
 		return nil, e.With(t)
 	}
-	if unifiedpush && t.RateVisitor() == nil {
+	if unifiedpush && s.config.EnableRateVisitor && t.RateVisitor() == nil {
 		// UnifiedPush clients must subscribe before publishing to allow proper subscriber-based rate limiting (see
 		// Rate-Topics header). The 5xx response is because some app servers (in particular Mastodon) will remove
 		// the subscription as invalid if any 400-499 code (except 429/408) is returned.
@@ -1188,14 +1188,19 @@ func parseSubscribeParams(r *http.Request) (poll bool, since sinceMarker, schedu
 // maybeSetRateVisitors sets the rate visitor on a topic (v.SetRateVisitor), indicating that all messages published
 // to that topic will be rate limited against the rate visitor instead of the publishing visitor.
 //
-// Setting the rate visitor is ony allowed if
+// Setting the rate visitor is ony allowed if the `enable-rate-visitor` setting is enabled, AND
 // - auth-file is not set (everything is open by default)
-// - the topic is reserved, and v.user is the owner
-// - the topic is not reserved, and v.user has write access
+// - or the topic is reserved, and v.user is the owner
+// - or the topic is not reserved, and v.user has write access
 //
 // Note: This TEMPORARILY also registers all topics starting with "up" (= UnifiedPush). This is to ease the transition
 // until the Android app will send the "Rate-Topics" header.
 func (s *Server) maybeSetRateVisitors(r *http.Request, v *visitor, topics []*topic, rateTopics []string) error {
+	// Bail out if not enabled
+	if !s.config.EnableRateVisitor {
+		return nil
+	}
+
 	// Make a list of topics that we'll actually set the RateVisitor on
 	eligibleRateTopics := make([]*topic, 0)
 	for _, t := range topics {

server/server.yml

@@ -235,6 +235,20 @@
 # visitor-attachment-total-size-limit: "100M"
 # visitor-attachment-daily-bandwidth-limit: "500M"
 
+# Rate limiting: Enable subscriber-based rate limiting (mostly used for UnifiedPush)
+#
+# If enabled, subscribers may opt to have published messages counted against their own rate limits, as opposed
+# to the publisher's rate limits. This is especially useful to increase the amount of messages that UnifiedPush
+# publishers (e.g. Matrix/Mastodon servers) are allowed to send.
+#
+# Once enabled, a client may send a "Rate-Topics: <topic1>,<topic2>,..." header when subscribing to topics via
+# HTTP stream, or websockets, thereby registering itself as the "rate visitor", i.e. the visitor whose rate limits
+# to use when publishing on this topic.
+#
+# For your home server, you likely DO NOT NEED THIS setting.
+#
+# enable-rate-visitors: false
+
 # Payments integration via Stripe
 #
 # - stripe-secret-key is the key used for the Stripe API communication. Setting this values

server/server_test.go

@@ -15,6 +15,7 @@ import (
 	"net/netip"
 	"os"
 	"path/filepath"
+	"runtime/debug"
 	"strings"
 	"sync"
 	"testing"
@@ -1291,7 +1292,9 @@ func TestServer_MatrixGateway_Push_Success(t *testing.T) {
 }
 
 func TestServer_MatrixGateway_Push_Failure_NoSubscriber(t *testing.T) {
-	s := newTestServer(t, newTestConfig(t))
+	c := newTestConfig(t)
+	c.EnableRateVisitor = true
+	s := newTestServer(t, c)
 	notification := `{"notification":{"devices":[{"pushkey":"http://127.0.0.1:12345/mytopic?up=1"}]}}`
 	response := request(t, s, "POST", "/_matrix/push/v1/notify", notification, nil)
 	require.Equal(t, 507, response.Code)
@@ -2029,6 +2032,7 @@ func TestServer_AnonymousUser_And_NonTierUser_Are_Same_Visitor(t *testing.T) {
 func TestServer_SubscriberRateLimiting_Success(t *testing.T) {
 	c := newTestConfigWithAuthFile(t)
 	c.VisitorRequestLimitBurst = 3
+	c.EnableRateVisitor = true
 	s := newTestServer(t, c)
 
 	// "Register" visitor 1.2.3.4 to topic "subscriber1topic" as a rate limit visitor
@@ -2082,6 +2086,7 @@ func TestServer_SubscriberRateLimiting_Success(t *testing.T) {
 func TestServer_SubscriberRateLimiting_UP_Only(t *testing.T) {
 	c := newTestConfigWithAuthFile(t)
 	c.VisitorRequestLimitBurst = 3
+	c.EnableRateVisitor = true
 	s := newTestServer(t, c)
 
 	// "Register" 5 different UnifiedPush visitors
@@ -2105,6 +2110,7 @@ func TestServer_SubscriberRateLimiting_UP_Only(t *testing.T) {
 func TestServer_Matrix_SubscriberRateLimiting_UP_Only(t *testing.T) {
 	c := newTestConfig(t)
 	c.VisitorRequestLimitBurst = 3
+	c.EnableRateVisitor = true
 	s := newTestServer(t, c)
 
 	// "Register" 5 different UnifiedPush visitors
@@ -2132,6 +2138,7 @@ func TestServer_Matrix_SubscriberRateLimiting_UP_Only(t *testing.T) {
 func TestServer_SubscriberRateLimiting_VisitorExpiration(t *testing.T) {
 	c := newTestConfig(t)
 	c.VisitorRequestLimitBurst = 3
+	c.EnableRateVisitor = true
 	s := newTestServer(t, c)
 
 	// "Register" rate visitor
@@ -2167,6 +2174,7 @@ func TestServer_SubscriberRateLimiting_VisitorExpiration(t *testing.T) {
 func TestServer_SubscriberRateLimiting_ProtectedTopics(t *testing.T) {
 	c := newTestConfigWithAuthFile(t)
 	c.AuthDefault = user.PermissionDenyAll
+	c.EnableRateVisitor = true
 	s := newTestServer(t, c)
 
 	// Create some ACLs
@@ -2214,6 +2222,7 @@ func TestServer_SubscriberRateLimiting_ProtectedTopics(t *testing.T) {
 func TestServer_SubscriberRateLimiting_ProtectedTopics_WithDefaultReadWrite(t *testing.T) {
 	c := newTestConfigWithAuthFile(t)
 	c.AuthDefault = user.PermissionReadWrite
+	c.EnableRateVisitor = true
 	s := newTestServer(t, c)
 
 	// Create some ACLs
@@ -2333,5 +2342,5 @@ func waitForWithMaxWait(t *testing.T, maxWait time.Duration, f func() bool) {
 		}
 		time.Sleep(100 * time.Millisecond)
 	}
-	t.Fatalf("Function f did not succeed after %v", maxWait)
+	t.Fatalf("Function f did not succeed after %v: %s", maxWait, debug.Stack())
 }