MQTT topics problems in latest mega branch

[crnjan]

Hi!

I'm working on a new plugin and noticed strange behaviour in latest develop (while being fine in last pre-release).

Long story short - when using CPLUGIN_005 (Home Assistant (openHAB) MQTT) to publish messages to broker, in latest develop the topic is not correct.

I.e. in my setup the topic should be

"ESP_Easy/xxx/MitsubishiHeatPump"

but its send as

"ESP_Easy/xxx/MitsubishiHeatPump "

(notice the space at the end). I checked what could be the issue and my guess is that change here is the problem.

So parseTemplate pads spaces at the end to match length:

  // padding spaces
  while (newString.length() < lineSize) {
    newString += ' ';
  }

but when we call the parseTemplate from parseControllerVariables, it still contains the placeholder %sysname%:

"%sysname%/xxx/%valname%"

which is replaced with "ESP_Easy" within the parseTemplate function and since "ESP_Easy" has 8 chars (compared to "%sysname%" with 9 chars), parseTemplate will append a space to the end:

"ESP_Easy/xxx/%valname% "

(notice the space at the end). Publisher will use this topic (with extra space) to publish the message ...

Hopefully my explanation makes sense :)

[giig1967g]

I never noticed it, probably because my broker trims the spaces, but it's indeed happenning.
One of my topic is: "ESPT12/d15/State<+ 3 spaces>"

[giig1967g]

@crnjan good catch by the way

[giig1967g]

this will fix it:

  // padding spaces
  while (newString.length() < lineSize) {
    newString += ' ';
  }
  STOP_TIMER(PARSE_TEMPLATE);
  checkRAM(F("parseTemplate3"));

//ADDING TRIM BEFORE RETURN
  newString.trim();
  return newString;
}

[giig1967g]

see #2867

[crnjan]

Hey! Thx for the prompt response. My only comment about the fix is that topic can actually contain spaces ... not sure if someone uses that in practice, but standard allows them ...

Topic Names and Topic Filters can include the space character

Taken from here.

[TD-er]

this will fix it:

  // padding spaces
  while (newString.length() < lineSize) {
    newString += ' ';
  }
  STOP_TIMER(PARSE_TEMPLATE);
  checkRAM(F("parseTemplate3"));

//ADDING TRIM BEFORE RETURN
  newString.trim();
  return newString;
}

It shouldn't be fixed there, but in the place where it is called.
As you can see in the code you quoted, it is done intentional. It was once meant to provide alignment for displaying on a display.
The call to this function also somewhere has a number provided to set the (minimal) string length.

I will make a patch for it, as topics obviously don't need to have trailing spaces, so it makes sense to sanitize the topics in the MQTT related code.

[TD-er]

Hey! Thx for the prompt response. My only comment about the fix is that topic can actually contain spaces ... not sure if someone uses that in practice, but standard allows them ...

Topic Names and Topic Filters can include the space character

Taken from here.

When trimming the topic, it removes only the leading and trailing spaces.
I think it is not too limiting to have a requirement not to have a leading or trailing space in a topic or filter, right?

[crnjan]

I too think that topics with trailing/leading spaces are not really used in practice. Thx for the fix, will give it a spin over the weekend!