From 761436c967a61aa32cdfe908535200eb688d4bae Mon Sep 17 00:00:00 2001
From: zhongwencool <zhongwencool@gmail.com>
Date: Thu, 5 May 2022 10:50:53 +0800
Subject: [PATCH] fix: don't allow empty username if username_as_clientid is
 true

---
 src/emqx_channel.erl       | 22 ++++++++++++++--------
 test/emqx_client_SUITE.erl | 12 +++++++++---
 2 files changed, 23 insertions(+), 11 deletions(-)

diff --git a/src/emqx_channel.erl b/src/emqx_channel.erl
index 92559e58e..530b04250 100644
--- a/src/emqx_channel.erl
+++ b/src/emqx_channel.erl
@@ -1216,13 +1216,18 @@ check_connect(ConnPkt, #channel{clientinfo = #{zone := Zone}}) ->
 %% Enrich Client Info
 
 enrich_client(ConnPkt, Channel = #channel{clientinfo = ClientInfo}) ->
-    {ok, NConnPkt, NClientInfo} = pipeline([fun set_username/2,
-                                            fun set_bridge_mode/2,
-                                            fun maybe_username_as_clientid/2,
-                                            fun maybe_assign_clientid/2,
-                                            fun fix_mountpoint/2
-                                           ], ConnPkt, ClientInfo),
-    {ok, NConnPkt, Channel#channel{clientinfo = NClientInfo}}.
+    Pipe = pipeline([fun set_username/2,
+                     fun set_bridge_mode/2,
+                     fun maybe_username_as_clientid/2,
+                     fun maybe_assign_clientid/2,
+                     fun fix_mountpoint/2
+                    ], ConnPkt, ClientInfo),
+    case Pipe of
+        {ok, NConnPkt, NClientInfo} ->
+            {ok, NConnPkt, Channel#channel{clientinfo = NClientInfo}};
+        {error, ReasonCode, NClientInfo} ->
+            {error, ReasonCode, Channel#channel{clientinfo = NClientInfo}}
+    end.
 
 set_username(#mqtt_packet_connect{username = Username},
              ClientInfo = #{username := undefined}) ->
@@ -1237,7 +1242,8 @@ maybe_username_as_clientid(_ConnPkt, ClientInfo = #{username := undefined}) ->
     {ok, ClientInfo};
 maybe_username_as_clientid(_ConnPkt, ClientInfo = #{zone := Zone, username := Username}) ->
     case emqx_zone:use_username_as_clientid(Zone) of
-        true  -> {ok, ClientInfo#{clientid => Username}};
+        true when Username =/= <<>> -> {ok, ClientInfo#{clientid => Username}};
+        true -> {error, ?RC_CLIENT_IDENTIFIER_NOT_VALID, ClientInfo};
         false -> ok
     end.
 
diff --git a/test/emqx_client_SUITE.erl b/test/emqx_client_SUITE.erl
index 4d69d11b3..d45e7a8cf 100644
--- a/test/emqx_client_SUITE.erl
+++ b/test/emqx_client_SUITE.erl
@@ -278,9 +278,15 @@ t_username_as_clientid(_) ->
     {ok, C} = emqtt:start_link([{username, Username}]),
     {ok, _} = emqtt:connect(C),
     #{clientinfo := #{clientid := Username}} = emqx_cm:get_chan_info(Username),
-    emqtt:disconnect(C).
-
-
+    emqtt:disconnect(C),
+    erlang:process_flag(trap_exit, true),
+    {ok, C1} = emqtt:start_link([{username, <<>>}]),
+    ?assertEqual({error, {client_identifier_not_valid, undefined}}, emqtt:connect(C1)),
+    receive
+        {'EXIT', _, {shutdown, client_identifier_not_valid}} -> ok
+    after 100 ->
+        throw({error, "expect_client_identifier_not_valid"})
+    end.
 
 t_certcn_as_clientid_default_config_tls(_) ->
     tls_certcn_as_clientid(default).