Fix bug that no update message expiry interval (#2101)

src/emqx_message.erl

@@ -23,6 +23,7 @@
 -export([set_headers/2]).
 -export([get_header/2, get_header/3, set_header/3]).
 -export([is_expired/1, update_expiry/1]).
+-export([remove_topic_alias/1]).
 -export([format/1]).
 
 -type(flag() :: atom()).
@@ -109,6 +110,9 @@ update_expiry(Msg = #message{headers = #{'Message-Expiry-Interval' := Interval},
 
 update_expiry(Msg) -> Msg.
 
+remove_topic_alias(Msg = #message{headers = Headers}) ->
+    Msg#message{headers = maps:remove('Topic-Alias', Headers)}.
+
 %% MilliSeconds
 elapsed(Since) ->
     max(0, timer:now_diff(os:timestamp(), Since) div 1000).

src/emqx_protocol.erl

@@ -617,12 +617,12 @@ deliver({connack, ?RC_SUCCESS, SP}, PState = #pstate{zone = Zone,
 deliver({connack, ReasonCode, SP}, PState) ->
     send(?CONNACK_PACKET(ReasonCode, SP), PState);
 
-deliver({publish, PacketId, Msg = #message{headers = Headers}}, PState = #pstate{mountpoint = MountPoint}) ->
+deliver({publish, PacketId, Msg}, PState = #pstate{mountpoint = MountPoint}) ->
     _ = emqx_hooks:run('message.delivered', [credentials(PState)], Msg),
     Msg1 = emqx_message:update_expiry(Msg),
     Msg2 = emqx_mountpoint:unmount(MountPoint, Msg1),
-    send(emqx_packet:from_message(PacketId, Msg2#message{headers = maps:remove('Topic-Alias', Headers)}), PState);
-    
+    send(emqx_packet:from_message(PacketId, emqx_message:remove_topic_alias(Msg2)), PState);
+
 deliver({puback, PacketId, ReasonCode}, PState) ->
     send(?PUBACK_PACKET(PacketId, ReasonCode), PState);