From 42b3c9b4d6ce08e6e495fe03da68dce9ac1166d6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E5=91=A8=E5=AD=90=E5=8D=9A?= <349832309@qq.com>
Date: Thu, 6 Sep 2018 14:47:34 +0800
Subject: [PATCH] Send DISCONNECT packet with reason code PROTOCOL_ERROR when
 topic is empty, add checks for topics

---
 src/emqx_protocol.erl |  3 +++
 src/emqx_topic.erl    | 13 ++++++++++---
 2 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/src/emqx_protocol.erl b/src/emqx_protocol.erl
index 013fa3c41..cee0af03a 100644
--- a/src/emqx_protocol.erl
+++ b/src/emqx_protocol.erl
@@ -208,6 +208,9 @@ received(Packet = ?PACKET(Type), PState) ->
         true ->
             {Packet1, PState1} = preprocess_properties(Packet, PState),
             process_packet(Packet1, inc_stats(recv, Type, PState1));
+        {'EXIT', {topic_filters_invalid, _Stacktrace}} ->
+            deliver({disconnect, ?RC_PROTOCOL_ERROR}, PState),
+            {error, topic_filters_invalid, PState};
         {'EXIT', {Reason, _Stacktrace}} ->
             deliver({disconnect, ?RC_MALFORMED_PACKET}, PState),
             {error, Reason, PState}
diff --git a/src/emqx_topic.erl b/src/emqx_topic.erl
index c244a40b3..3dcad0b33 100644
--- a/src/emqx_topic.erl
+++ b/src/emqx_topic.erl
@@ -184,9 +184,16 @@ parse(Topic = <<"$share/", _/binary>>, #{share := _Group}) ->
     error({invalid_topic, Topic});
 parse(<<"$queue/", Topic1/binary>>, Options) ->
     parse(Topic1, maps:put(share, <<"$queue">>, Options));
-parse(<<"$share/", Topic1/binary>>, Options) ->
-    [Group, Topic2] = binary:split(Topic1, <<"/">>),
-    {Topic2, maps:put(share, Group, Options)};
+parse(Topic = <<"$share/", Topic1/binary>>, Options) ->
+    case binary:split(Topic1, <<"/">>) of
+        [<<>>] -> error({invalid_topic, Topic});
+        [_] -> error({invalid_topic, Topic});
+        [Group, Topic2] -> 
+            case binary:match(Group, [<<"/">>, <<"+">>, <<"#">>]) of 
+                nomatch -> error({invalid_topic, Topic});
+                _ -> {Topic2, maps:put(share, Group, Options)}
+            end
+    end;
 parse(Topic, Options) ->
     {Topic, Options}.