From 8ff9a03df3b93076d9c0b477569540cef241bc05 Mon Sep 17 00:00:00 2001
From: ieQu1 <99872536+ieQu1@users.noreply.github.com>
Date: Thu, 9 Jun 2022 13:46:56 +0200
Subject: [PATCH 1/2] fix(retainer): Handle zero-length topic levels

---
 apps/emqx_retainer/src/emqx_retainer_index.erl        | 4 ++--
 apps/emqx_retainer/test/emqx_retainer_index_SUITE.erl | 8 ++++++++
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/apps/emqx_retainer/src/emqx_retainer_index.erl b/apps/emqx_retainer/src/emqx_retainer_index.erl
index 0d739e2b0..3f5b87b90 100644
--- a/apps/emqx_retainer/src/emqx_retainer_index.erl
+++ b/apps/emqx_retainer/src/emqx_retainer_index.erl
@@ -176,11 +176,11 @@ condition([NIndex | OtherIndex], ['+' | OtherTokens], N, IndexMatch, OtherMatch)
 condition(Index, ['+' | OtherTokens], N, IndexMatch, OtherMatch) ->
     condition(Index, OtherTokens, N + 1, IndexMatch, ['_' | OtherMatch]);
 condition([NIndex | OtherIndex], [Token | OtherTokens], N, IndexMatch, OtherMatch) when
-    NIndex =:= N, is_binary(Token)
+    NIndex =:= N, is_binary(Token) orelse Token =:= ''
 ->
     condition(OtherIndex, OtherTokens, N + 1, [Token | IndexMatch], OtherMatch);
 condition(Index, [Token | OtherTokens], N, IndexMatch, OtherMatch) when
-    is_binary(Token)
+    is_binary(Token) orelse Token =:= ''
 ->
     condition(Index, OtherTokens, N + 1, IndexMatch, [Token | OtherMatch]).
 
diff --git a/apps/emqx_retainer/test/emqx_retainer_index_SUITE.erl b/apps/emqx_retainer/test/emqx_retainer_index_SUITE.erl
index ce37f2788..793df0410 100644
--- a/apps/emqx_retainer/test/emqx_retainer_index_SUITE.erl
+++ b/apps/emqx_retainer/test/emqx_retainer_index_SUITE.erl
@@ -193,6 +193,14 @@ t_condition_index(_Config) ->
             [1],
             [<<"a">>, '#']
         )
+    ),
+
+    ?assertEqual(
+        {[1, 2, 3], {['', <<"saya">>, '_'], []}},
+        emqx_retainer_index:condition(
+            [1, 2, 3],
+            ['', <<"saya">>, '+']
+        )
     ).
 
 t_restore_topic(_Config) ->

From 4e767979278a37e46c100355b0a0a9ce0b3bcfba Mon Sep 17 00:00:00 2001
From: Ilya Averyanov <av@rubybox.ru>
Date: Fri, 10 Jun 2022 12:33:27 +0300
Subject: [PATCH 2/2] fix(retainer): add additional test

---
 apps/emqx_retainer/test/emqx_retainer_SUITE.erl | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/apps/emqx_retainer/test/emqx_retainer_SUITE.erl b/apps/emqx_retainer/test/emqx_retainer_SUITE.erl
index 100477634..74944f362 100644
--- a/apps/emqx_retainer/test/emqx_retainer_SUITE.erl
+++ b/apps/emqx_retainer/test/emqx_retainer_SUITE.erl
@@ -220,14 +220,22 @@ t_wildcard_subscription(_) ->
         <<"this is a retained message 2">>,
         [{qos, 0}, {retain, true}]
     ),
+    emqtt:publish(
+        C1,
+        <<"/x/y/z">>,
+        <<"this is a retained message 3">>,
+        [{qos, 0}, {retain, true}]
+    ),
 
     {ok, #{}, [0]} = emqtt:subscribe(C1, <<"retained/+">>, 0),
     {ok, #{}, [0]} = emqtt:subscribe(C1, <<"retained/+/b/#">>, 0),
-    ?assertEqual(3, length(receive_messages(3))),
+    {ok, #{}, [0]} = emqtt:subscribe(C1, <<"/+/y/#">>, 0),
+    ?assertEqual(4, length(receive_messages(4))),
 
     emqtt:publish(C1, <<"retained/0">>, <<"">>, [{qos, 0}, {retain, true}]),
     emqtt:publish(C1, <<"retained/1">>, <<"">>, [{qos, 0}, {retain, true}]),
     emqtt:publish(C1, <<"retained/a/b/c">>, <<"">>, [{qos, 0}, {retain, true}]),
+    emqtt:publish(C1, <<"/x/y/z">>, <<"">>, [{qos, 0}, {retain, true}]),
     ok = emqtt:disconnect(C1).
 
 t_message_expiry(_) ->