IRMQTTServer: add MQTT_SERVER_AUTODETECT_ENABLE

[helen-fornazier]

The MQTT broker can change address if its IP is not static.

Add MQTT_SERVER_AUTODETECT_ENABLE option which detects the broker that
advertises the service _mqtt._tcp

If the broker changes address it won't be a problem. If the broker
doesn't advertise the service, then use the pre-configured IP as before.

Example testing on Debian:

$ apt install mosquitto avahi-daemon

$ cat <<EOT >> /etc/mosquitto/conf.d/my_broker.conf
listener 1883 0.0.0.0
allow_anonymous true
EOT

$ cat <<EOT >> /etc/avahi/services/mqtt.service
<?xml version="1.0" standalone='no'?><!--*-nxml-*-->
<!DOCTYPE service-group SYSTEM "avahi-service.dtd">
<service-group>
  <name replace-wildcards="yes">%h</name>
  <service protocol="ipv4">
    <type>_mqtt._tcp</type>
    <port>1883</port>
  </service>
</service-group>
EOT

$ systemctl start mosquitto
$ systemctl start avahi-daemon

[crankyoldgit]

First off, thanks for this. It looks like a great addition to the example/program!

Can I get you to please bump the version number in IRMQTTServer.h to 1.7.0 please as a result of your improvement?
e.g.

#define _MY_VERSION_ "v1.7.0"

and there are a few automatic linter issue that need to be addressed as well before we can merge.
e.g.

examples/IRMQTTServer/IRMQTTServer.ino:2001:  At least two spaces is best between code and comments  [whitespace/comments] [2]
examples/IRMQTTServer/IRMQTTServer.ino:2035:  At least two spaces is best between code and comments  [whitespace/comments] [2]
examples/IRMQTTServer/IRMQTTServer.ino:2234:  At least two spaces is best between code and comments  [whitespace/comments] [2]
examples/IRMQTTServer/IRMQTTServer.ino:2350:  At least two spaces is best between code and comments  [whitespace/comments] [2]

I assume you've tested this with flag enabled and there being no zeroconf/avahi _mqtt._tcp service advertised. i.e. What happens?

[crankyoldgit]

Putting that new code/define etc behind the MQTT_ENABLE flag etc stops the code from breaking when MQTT is disabled.
e.g. When MQTT_ENABLE is set to false your code currently has compile errors of:

/home/runner/work/IRremoteESP8266/IRremoteESP8266/examples/IRMQTTServer/IRMQTTServer.ino: In function 'void mqtt_detect_server()':
/home/runner/work/IRremoteESP8266/IRremoteESP8266/examples/IRMQTTServer/IRMQTTServer.ino:1995:11: error: 'MqttServer' was not declared in this scope
 1995 |   strncpy(MqttServer, MDNS.IP(0).toString().c_str(), kHostnameLength);
      |           ^~~~~~~~~~
/home/runner/work/IRremoteESP8266/IRremoteESP8266/examples/IRMQTTServer/IRMQTTServer.ino:1996:11: error: 'MqttPort' was not declared in this scope; did you mean 'kHttpPort'?
 1996 |   strncpy(MqttPort, String(MDNS.port(0)).c_str(), kPortLength);
      |           ^~~~~~~~
      |           kHttpPort
*** [.pio/build/d1_mini_no_mqtt/src/IRMQTTServer.ino.cpp.o] Error 1
========================== [FAILED] Took 8.28 seconds ==========================

You can verify this by building the following target environments:

IRremoteESP8266/examples/IRMQTTServer/platformio.ini

Lines 39 to 44 in 846daf5

	[env:d1_mini_no_mqtt]
	board = d1_mini
	build_flags =
	${env.build_flags}
	-DMQTT_ENABLE=false
	lib_deps = ${common_esp8266.lib_deps_external}

or

IRremoteESP8266/examples/IRMQTTServer/platformio.ini

Lines 56 to 70 in 846daf5

	; This is just to help enable swapping IRMQTTServer via OTA on platforms with
	; limited flash space. It doesn't do *ANY* IR stuff. It has almost everything
	; turned off except OTA over http.
	; Produces a ".bin" file of ~380k.
	[env:esp8266_1m_OTA_minimal]
	board = esp01_1m
	board_build.ldscript = eagle.flash.1m64.ld
	build_flags =
	${env.build_flags}
	-DMQTT_ENABLE=false
	-D_IR_ENABLE_DEFAULT_=false
	-DEXAMPLES_ENABLE=false
	-DMDNS_ENABLE=false
	-DUSE_DECODED_AC_SETTINGS=false
	lib_deps = ${common_esp8266.lib_deps_external}

[helen-fornazier]

First off, thanks for this. It looks like a great addition to the example/program!

My pleasure, thanks for this example/program, it is really useful.
And thank you for the review!

Can I get you to please bump the version number in IRMQTTServer.h to 1.7.0 please as a result of your improvement? e.g.

#define _MY_VERSION_ "v1.7.0"

Sure

and there are a few automatic linter issue that need to be addressed as well before we can merge. e.g.

Which command do you use to run linter? (So I can run in my local machine too).

examples/IRMQTTServer/IRMQTTServer.ino:2001:  At least two spaces is best between code and comments  [whitespace/comments] [2]
examples/IRMQTTServer/IRMQTTServer.ino:2035:  At least two spaces is best between code and comments  [whitespace/comments] [2]
examples/IRMQTTServer/IRMQTTServer.ino:2234:  At least two spaces is best between code and comments  [whitespace/comments] [2]
examples/IRMQTTServer/IRMQTTServer.ino:2350:  At least two spaces is best between code and comments  [whitespace/comments] [2]

I assume you've tested this with flag enabled and there being no zeroconf/avahi _mqtt._tcp service advertised. i.e. What happens?

If no server is found, then it doesn't modify the variables MqttServer and MqttPort, so it uses wherever is pre-configured, or from first boot wifi config, or from loadConfigFile(), i.e. it behaves like before this patch.

If in one boot the mqtt server is found, then it modifies MqttServer and MqttPort, and they get saved if saveConfig() is called (i.e. if user modifies something in the web config page). So in the next boot, if it doesn't find the server through mDNS, it will reuse the address and port from previous boot.

[crankyoldgit]

Which command do you use to run linter? (So I can run in my local machine too).

IRremoteESP8266/.github/workflows/Lint.yml

Line 28 in 846daf5

cpplint --extensions=c,cc,cpp,ino --headers=h,hpp {src,src/locale,test,tools}/*.{h,c,cc,cpp,hpp,ino} examples/*/*.{h,c,cc,cpp,hpp,ino}

You will probably need to install cpplint via:

IRremoteESP8266/.github/workflows/Lint.yml

Line 20 in 846daf5

pip install cpplint

[crankyoldgit]

Thanks for the updates. Approved.

[crankyoldgit]

FYI, the changes mentioned above have now been included in the new v2.8.2 release of the library.