Update server version

Add the OnUnsubscribed hook to the unsubscribeClient method，and change the unsubscribeClient to externally visible. In a clustered environment, if a client is disconnected and then connected to another node, the subscriptions on the previous node need to be cleared.

clients.go

@@ -383,6 +383,10 @@ func (cl *Client) ReadFixedHeader(fh *packets.FixedHeader) error {
 		return err
 	}
 
+	if cl.ops.capabilities.MaximumPacketSize > 0 && uint32(fh.Remaining+1) > cl.ops.capabilities.MaximumPacketSize {
+		return packets.ErrPacketTooLarge // [MQTT-3.2.2-15]
+	}
+
 	atomic.AddInt64(&cl.ops.info.BytesReceived, int64(bu+1))
 	return nil
 }

clients_test.go

@@ -350,6 +350,22 @@ func TestClientReadFixedHeaderDecodeError(t *testing.T) {
 	require.Error(t, err)
 }
 
+func TestClientReadFixedHeaderPacketOversized(t *testing.T) {
+	cl, r, _ := newTestClient()
+	cl.ops.capabilities.MaximumPacketSize = 2
+	defer cl.Stop(errClientStop)
+
+	go func() {
+		r.Write(packets.TPacketData[packets.Publish].Get(packets.TPublishQos1Dup).RawBytes)
+		r.Close()
+	}()
+
+	fh := new(packets.FixedHeader)
+	err := cl.ReadFixedHeader(fh)
+	require.Error(t, err)
+	require.ErrorIs(t, err, packets.ErrPacketTooLarge)
+}
+
 func TestClientReadFixedHeaderReadEOF(t *testing.T) {
 	cl, r, _ := newTestClient()
 	defer cl.Stop(errClientStop)

server.go

@@ -26,7 +26,7 @@ import (
 )
 
 const (
-	Version                        = "2.0.5" // the current server version.
+	Version                        = "2.0.7" // the current server version.
 	defaultSysTopicInterval int64  = 1       // the interval between $SYS topic publishes
 	defaultFanPoolSize      uint64 = 32      // the number of concurrent workers in the pool
 	defaultFanPoolQueueSize uint64 = 1024    // the capacity of each worker queue
@@ -376,7 +376,7 @@ func (s *Server) attachClient(cl *Client, listener string) error {
 	expire := (cl.Properties.ProtocolVersion == 5 && cl.Properties.Props.SessionExpiryIntervalFlag && cl.Properties.Props.SessionExpiryInterval == 0) || (cl.Properties.ProtocolVersion < 5 && cl.Properties.Clean)
 	s.hooks.OnDisconnect(cl, err, expire)
 	if expire {
-		s.unsubscribeClient(cl)
+		s.UnsubscribeClient(cl)
 		cl.ClearInflights(math.MaxInt64, 0)
 		s.Clients.Delete(cl.ID) // [MQTT-4.1.0-2] ![MQTT-3.1.2-23]
 	}
@@ -455,7 +455,7 @@ func (s *Server) inheritClientSession(pk packets.Packet, cl *Client) bool {
 		defer existing.Unlock()
 		s.DisconnectClient(existing, packets.ErrSessionTakenOver)                                 // [MQTT-3.1.4-3]
 		if pk.Connect.Clean || (existing.Properties.Clean && cl.Properties.ProtocolVersion < 5) { // [MQTT-3.1.2-4] [MQTT-3.1.4-4]
-			s.unsubscribeClient(existing)
+			s.UnsubscribeClient(existing)
 			existing.ClearInflights(math.MaxInt64, 0)
 			return false // [MQTT-3.2.2-3]
 		}
@@ -1072,14 +1072,20 @@ func (s *Server) processUnsubscribe(cl *Client, pk packets.Packet) error {
 	return cl.WritePacket(ack)
 }
 
-// unsubscribeClient unsubscribes a client from all of their subscriptions.
-func (s *Server) unsubscribeClient(cl *Client) {
-	for k := range cl.State.Subscriptions.GetAll() {
+// UnsubscribeClient unsubscribes a client from all of their subscriptions.
+func (s *Server) UnsubscribeClient(cl *Client) {
+	i := 0
+	filterMap := cl.State.Subscriptions.GetAll()
+	filters := make([]packets.Subscription, len(filterMap))
+	for k, v := range filterMap {
 		cl.State.Subscriptions.Delete(k)
 		if s.Topics.Unsubscribe(k, cl.ID) {
 			atomic.AddInt64(&s.Info.Subscriptions, -1)
 		}
+		filters[i] = v
+		i++
 	}
+	s.hooks.OnUnsubscribed(cl, packets.Packet{Filters: filters})
 }
 
 // processAuth processes an Auth packet.
@@ -1126,12 +1132,15 @@ func (s *Server) DisconnectClient(cl *Client, code packets.Code) error {
 
 	// We already have a code we are using to disconnect the client, so we are not
 	// interested if the write packet fails due to a closed connection (as we are closing it).
-	_ = cl.WritePacket(out)
+	err := cl.WritePacket(out)
 	if !s.Options.Capabilities.Compatibilities.PassiveClientDisconnect {
 		cl.Stop(code)
+		if code.Code >= packets.ErrUnspecifiedError.Code {
+			return code
+		}
 	}
 
-	return code
+	return err
 }
 
 // publishSysTopics publishes the current values to the server $SYS topics.

server_test.go

@@ -844,7 +844,7 @@ func TestServerUnsubscribeClient(t *testing.T) {
 	s.Topics.Subscribe(cl.ID, pk)
 	subs := s.Topics.Subscribers("a/b/c")
 	require.Equal(t, 1, len(subs.Subscriptions))
-	s.unsubscribeClient(cl)
+	s.UnsubscribeClient(cl)
 	subs = s.Topics.Subscribers("a/b/c")
 	require.Equal(t, 0, len(subs.Subscriptions))
 }
@@ -2291,6 +2291,21 @@ func TestServerRecievePacketDisconnectClientZeroNonZero(t *testing.T) {
 	require.Equal(t, packets.TPacketData[packets.Disconnect].Get(packets.TDisconnectZeroNonZeroExpiry).RawBytes, buf)
 }
 
+func TestServerRecievePacketDisconnectClient(t *testing.T) {
+	s := newServer()
+	cl, r, w := newTestClient()
+
+	go func() {
+		err := s.DisconnectClient(cl, packets.CodeDisconnect)
+		require.NoError(t, err)
+		w.Close()
+	}()
+
+	buf, err := io.ReadAll(r)
+	require.NoError(t, err)
+	require.Equal(t, packets.TPacketData[packets.Disconnect].Get(packets.TDisconnect).RawBytes, buf)
+}
+
 func TestServerProcessPacketDisconnect(t *testing.T) {
 	s := newServer()
 	cl, _, _ := newTestClient()