MDNS.addService not working

[natcl]

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Hardware:

Board: Adafruit ESP32 Feather
Core Installation/update date:
IDE name: Arduino 1.8.5 on MacOS
Flash Frequency: ?80Mhz?
Upload Speed:

Description:

Using the mDNS_Web_Server example sketch, I can't get the addService method to work. The sketch runs fine, I can access my ESP32 using the esp32.local URL but it doesn't get advertised on the network when checking with different mdns browsers. Similar code works with the esp8266. Also browsing services seems to work.

[baggior]

I confirm this problem even with a generic ESP32 board
board = esp32dev

[baggior]

#387

[beegee-tokyo]

Works without problems for me, but I am not using MDNS.begin, instead I am using ArduinoOTA to start the mDNS service.

ArduinoOTA.setHostname("ESP32-Test-2481CE9C");
ArduinoOTA.begin();
// addd some more service text
MDNS.addServiceTxt("_arduino", "_tcp", "service", "MHC");
MDNS.addServiceTxt("_arduino", "_tcp", "type", "TestBoard");
MDNS.addServiceTxt("_arduino", "_tcp", "id", "ESP32-Test");

Result of Service Browser on my Android tablet:

I am using Visual Studio Code/PlatformIO.
Platform Espressif32 (Stage) Version 1392c2a

[natcl]

But that’s to advertize the Arduino service. If you want to advertize a generic service (like OSC over UDP) it doesn’t work.

[baggior]

No the service is not shown even in Service Browser forAndroid
The same code works for ESP8266 but not for ESP32
I did

WiFi.setHostname(..)
MDNS.begin(..)
MDNS.addService(..)

[beegee-tokyo]

Maybe it works for me, because I am using the "staging" version, but when I do

	WiFi.setHostname("ESP32-Test-mDNS");
	MDNS.begin("ESP32-Test-mDNS");
	MDNS.addService("_osc","_udp",4500);
	MDNS.addServiceTxt("_osc","_udp","does","it");
	MDNS.addServiceTxt("_osc","_udp","work","?");
	MDNS.addServiceTxt("_osc","_udp","yes","!");

The result in Android service browser is

I see that you are saying you use MDNS.begin();. That throws a compilation error for me. MDNS.begin() requires a parameter which is the hostName.

src\ota.cpp: In function 'void activateOTA(const char*, const char*)':
src\ota.cpp:126:13: error: no matching function for call to 'MDNSResponder::begin()'
MDNS.begin();
^
In file included from src\setup.h:20:0,
from src\ota.cpp:1:
C:\users\beegee\.platformio\packages\framework-arduinoespressif32\libraries\ESPmDNS\src/ESPmDNS.h:57:8: note: candidate: bool MDNSResponder::begin(const char*)
bool begin(const char* hostName);
^
C:\users\beegee\.platformio\packages\framework-arduinoespressif32\libraries\ESPmDNS\src/ESPmDNS.h:57:8: note:   candidate expects 1 argument, 0 provided
*** [.pioenvs\esp32dev\src\ota.o] Error 1

And again, I am on the latest staging version:

[beegee-tokyo]

Ok, I started comparing the ESPmDNS.cpp (ESP32) with the ESP8266mDNS.cpp (ESP8266) and found some interesting differences.
On the ESP32 version you have to make sure

• that the service name is lower case
• that the service name and protocol starts with an '_' e.g. '_udp'

On the ESP8266 version the library takes care of

• copying service name to lower case
• adding the '_' in front if necessary.

So maybe try

• to change your service name into all lower case and add the '_' in front
• to change your protocol name into all lower case and add the '_' in front

It nether bothered me because I did the same all my ESP8266 projects and ESP32 projects already, so I never saw the problem.

@me-no-dev - Maybe ESPmDNS needs some update to be 100% compatible with the ESP8266 version.

[xinort]

Doesn't work for me either. And hasn't for quite a while.

Edit: I changed "tcp" to "_tcp" and it works!

[beegee-tokyo]

I tried it on

• Arduino IDE with the lastest master version of the platform
• PlatformIO/Visual Studio Code with the lastest master version of the platform
• PlatformIO/Visual Studio Code with the lastest staging version of the platform

I tried it with the ESP32 example codes

• mDNS_Web_Server.ino
• mDNS-SD_Extended.ino

In the example codes I only made the changes from "http", "tcp" to "_http", "_tcp" to get it working.

One thing I found out is that after flashing, the mDNS advertise sometimes couldn't be found immediately. Then I had to do a hard reset (push reset button or power off/on cycle). After a hard reset it worked always.

Can you give me a code excerpt that shows the initialization and adding of services?

[baggior]

@beegee-tokyo I've added the "_" prefix to service and protocol and now it works..
The service is published and visible in Android service browser..

TO BE DOCUMENTED..

but the query method doesn't work since MDNS.query cannot find any result..( with or without the prefix)

Anyway there is a bug or a serious inconsistency, since in the query method code the "_" prefix is added anyway while int the addService method the prefix is required to be provided in the input parameter..

[beegee-tokyo]

Anyway there is a bug or a serious inconsistency, since in the query method code the "_" prefix is added anyway while int the addService method the prefix is required to be provided in the input parameter..

Saw this as well. Inconsistent and in general the ESP8266 and ESP32 mDNS should work the same.

But happy I could at least help with the advertising.
I tried the query example mDNS-SD_Extended.ino and it worked for me. It found all mDNS services in my system. Will copy my working code into a Gist and post the link tomorrow.

[baggior]

@beegee-tokyo so can you fix that all?
commit and open a pull request?

[beegee-tokyo]

Will try in the next days.