mDNS is a multicast UDP service that is used to provide local network service and host discovery.
mDNS is installed by default on most operating systems or is available as separate package. On ``Mac OS`` it is installed by default and is called ``Bonjour``. Apple releases an installer for ``Windows`` that can be found `on Apple's support page <https://support.apple.com/downloads/bonjour%2520for%2520windows>`_. On ``Linux``, mDNS is provided by `avahi <https://github.com/lathiat/avahi>`_ and is usually installed by default.
mDNS Properties
^^^^^^^^^^^^^^^
*``hostname``: the hostname that the device will respond to. If not set, the ``hostname`` will be read from the interface. Example: ``my-esp32`` will resolve to ``my-esp32.local``
*``default_instance``: friendly name for your device, like ``Jhon's ESP32 Thing``. If not set, ``hostname`` will be used.
Example method to start mDNS for the STA interface and set ``hostname`` and ``default_instance``:
..highlight:: c
::
void start_mdns_service()
{
//initialize mDNS service
esp_err_t err = mdns_init();
if (err) {
printf("MDNS Init failed: %d\n", err);
return;
}
//set hostname
mdns_hostname_set("my-esp32");
//set default instance
mdns_instance_name_set("Jhon's ESP32 Thing");
}
mDNS Services
^^^^^^^^^^^^^
mDNS can advertise information about network services that your device offers. Each service is defined by a few properties.
*``instance_name``: friendly name for your service, like ``Jhon's ESP32 Web Server``. If not defined, ``default_instance`` will be used.
*``service_type``: (required) service type, prepended with underscore. Some common types can be found `here <http://www.dns-sd.org/serviceTypes.html>`_.
*``proto``: (required) protocol that the service runs on, prepended with underscore. Example: ``_tcp`` or ``_udp``
*``port``: (required) network port that the service runs on
*``txt``: ``{var, val}`` array of strings, used to define properties for your service
Example method to add a few services and different properties::
