Hierarchical topics not handled correctly

[mtappler]

Hierarchical topics are not handled correctly. More concretely, if I subscribe to a topic at a high level in the hierarchy I will also receive messages published at a lower level.

I tested the following simple example:

1. Connect with Client C1 and receive ConnAck
2. Subscribe with C1 to topic "my_topic" and receive SubAck
3. Publish message "my_message" with C1 and QoS 1 to "my_topic/other_topic" and receive PubAck and additionally a Publish-message for "my_topic/other_topic" with message "my_message"

Thus, the subscription to "my_topic" works like a subscription to "my_topic/#". I would interpret this as a violation of the MQTT-standard and I also checked with emqtt and mosquitto, which would not send a Publish in response to the last step.

A quick fix would be to change Line 623 from
match_pattern = re.compile(a_filter.replace('#', '.*').replace('$', '\$').replace('+', '[/\$\s\w\d]+'))
to
match_pattern = re.compile("^"+a_filter.replace('#', '.*').replace('$', '\$').replace('+', '[/\$\s\w\d]+')+"$")

However, I am neither a Python-expert nor did I test the fix thoroughly.

[mtappler]

Thank you for fixing the issue so fast!

I do not know whether I should open another issue as this is kind of related, but I will do so if necessary. There is another problem, which existed before and persists with the fix committed yesterday. The single-level wildcards denoted by + should not match more than one level, but the replacement-regex allows matching strings as well as level-separators /, so I guess replace('+', '[/\$\s\w\d]+') should be changed to something like replace('+', '[^/\$\s\w\d]+'), i.e. it should only match characters unequal to a /.
I should note that I did not evaluate this fix thoroughly either. I just checked with some string and did not test special cases like zero length topic names.

However, by doing so, the issue raised yesterday would still persist I think. Since the regex would partially match, by subscribing to a/+/b, one would also receive messages published for a/something/b/anotherthing.