Ignore retain as published v3 (#142)

* Optimise Capabilities struct alignment

* Only use RetainAsPublished for v5 clients

packets/tpackets.go

@@ -1824,32 +1824,22 @@ var TPacketData = map[byte]TPacketCases{
 			Case: TPublishRetainMqtt5,
 			Desc: "retain mqtt5",
 			RawBytes: []byte{
-				Publish<<4 | 1<<0, 35, // Fixed header
+				Publish<<4 | 1<<0, 19, // Fixed header
 				0, 5, // Topic Name - LSB+MSB
 				'a', '/', 'b', '/', 'c', // Topic Name
-				16, // properties length
-				38, // User Properties (38)
-				0, 5, 'h', 'e', 'l', 'l', 'o',
-				0, 6, 228, 184, 150, 231, 149, 140,
+				0,                                                     // properties length
 				'h', 'e', 'l', 'l', 'o', ' ', 'm', 'o', 'c', 'h', 'i', // Payload
 			},
 			Packet: &Packet{
 				ProtocolVersion: 5,
 				FixedHeader: FixedHeader{
 					Type:      Publish,
 					Retain:    true,
-					Remaining: 35,
+					Remaining: 19,
 				},
-				TopicName: "a/b/c",
-				Properties: Properties{
-					User: []UserProperty{
-						{
-							Key: "hello",
-							Val: "世界",
-						},
-					},
-				},
-				Payload: []byte("hello mochi"),
+				TopicName:  "a/b/c",
+				Properties: Properties{},
+				Payload:    []byte("hello mochi"),
 			},
 		},
 		{

server.go

@@ -26,7 +26,7 @@ import (
 )
 
 const (
-	Version                        = "2.1.4" // the current server version.
+	Version                        = "2.1.5" // 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
@@ -61,13 +61,13 @@ type Capabilities struct {
 	ReceiveMaximum               uint16
 	TopicAliasMaximum            uint16
 	ServerKeepAlive              uint16
+	SharedSubAvailable           byte
+	MinimumProtocolVersion       byte
 	Compatibilities              Compatibilities
 	MaximumQos                   byte
 	RetainAvailable              byte
 	WildcardSubAvailable         byte
 	SubIDAvailable               byte
-	SharedSubAvailable           byte
-	MinimumProtocolVersion       byte
 }
 
 // Compatibilities provides flags for using compatibility modes.
@@ -785,7 +785,7 @@ func (s *Server) publishToClient(cl *Client, sub packets.Subscription, pk packet
 	}
 
 	out := pk.Copy(false)
-	if !sub.RetainAsPublished { // ![MQTT-3.3.1-13]
+	if cl.Properties.ProtocolVersion == 5 && !sub.RetainAsPublished { // ![MQTT-3.3.1-13]
 		out.FixedHeader.Retain = false // [MQTT-3.3.1-12]
 	}
 

server_test.go

@@ -1023,7 +1023,7 @@ func TestServerProcessPacketPublishAndReceive(t *testing.T) {
 		w2.Close()
 	}()
 
-	require.Equal(t, packets.TPacketData[packets.Publish].Get(packets.TPublishBasic).RawBytes, <-receiverBuf)
+	require.Equal(t, packets.TPacketData[packets.Publish].Get(packets.TPublishRetain).RawBytes, <-receiverBuf)
 	require.Equal(t, 1, len(s.Topics.Messages("a/b/c")))
 }
 
@@ -1537,7 +1537,7 @@ func TestPublishRetainedToClient(t *testing.T) {
 	subbed := s.Topics.Subscribe(cl.ID, packets.Subscription{Filter: "a/b/c", Qos: 2})
 	require.True(t, subbed)
 
-	retained := s.Topics.RetainMessage(*packets.TPacketData[packets.Publish].Get(packets.TPublishRetain).Packet)
+	retained := s.Topics.RetainMessage(*packets.TPacketData[packets.Publish].Get(packets.TPublishRetainMqtt5).Packet)
 	require.Equal(t, int64(1), retained)
 
 	go func() {
@@ -1548,7 +1548,7 @@ func TestPublishRetainedToClient(t *testing.T) {
 
 	buf, err := io.ReadAll(r)
 	require.NoError(t, err)
-	require.Equal(t, packets.TPacketData[packets.Publish].Get(packets.TPublishBasic).RawBytes, buf)
+	require.Equal(t, packets.TPacketData[packets.Publish].Get(packets.TPublishRetain).RawBytes, buf)
 }
 
 func TestPublishRetainedToClientIsShared(t *testing.T) {
@@ -2064,7 +2064,7 @@ func TestServerProcessSubscribeWithRetain(t *testing.T) {
 	require.NoError(t, err)
 	require.Equal(t, append(
 		packets.TPacketData[packets.Suback].Get(packets.TSuback).RawBytes,
-		packets.TPacketData[packets.Publish].Get(packets.TPublishBasic).RawBytes...,
+		packets.TPacketData[packets.Publish].Get(packets.TPublishRetain).RawBytes...,
 	), buf)
 }
 
@@ -2452,7 +2452,7 @@ func TestServerSendLWTDelayed(t *testing.T) {
 		recv <- buf
 	}()
 
-	require.Equal(t, packets.TPacketData[packets.Publish].Get(packets.TPublishBasic).RawBytes, <-recv)
+	require.Equal(t, packets.TPacketData[packets.Publish].Get(packets.TPublishRetain).RawBytes, <-recv)
 }
 
 func TestServerReadStore(t *testing.T) {