NetxDuo mDNS and DHCP conflict because of ST Ethernet driver

[sssooo]

Hi all,

I've noticed that a DHCP client can not get an IP address from the server if both mDNS server and DHCP client are enabled.

The reason seems to be in ST Ethernet driver (nx_stm32_eth_driver.c):

static UINT  _nx_driver_hardware_initialize(NX_IP_DRIVER *driver_req_ptr)
{
...
  FilterConfig.BroadcastFilter = ENABLE;
...
}


static UINT  _nx_driver_hardware_multicast_join(NX_IP_DRIVER *driver_req_ptr)
{
  /* Increase the multicast count.  */
  nx_driver_information.nx_driver_information_multicast_count++;

  /* Enable multicast frame reception.  */
  FilterConfig.PassAllMulticast = ENABLE;
  HAL_ETH_SetMACFilterConfig(&eth_handle, &FilterConfig);

  /* Return success.  */
  return(NX_SUCCESS);
}

In _nx_driver_hardware_initialize() FilterConfig is just prepared, there is no HAL_ETH_SetMACFilterConfig() call.

That's why DHCP works OK if mDNS is not used.

If mDNS is active, it calls _nx_driver_hardware_multicast_join() and applies a prepared FilterConfig  where BroadcastFilter is ENABLED.

This blocks DHCP work.

Fix seems to be: set BroadcastFilter to DISABLE in _nx_driver_hardware_initialize()

Is such a fix correct?

[STackPointer64]

Hello @sssooo, and welcome to ST Community!

Could you please provide a minimal version of the project that reproduces this issue? This will help us analyze the problem more efficiently. Thank you!

Best regards,

[sssooo]

Hello,

please see attached project for NUCLEO-H563ZI.

If you will try the project as is, DHCP and mDNS works ok.

This is because I've manually set BroadcastFilter to DISABLE in _nx_driver_hardware_initialize().

You can try to change it to ENABLE and DHCP will not work (it will not receive a broadcast packet from DHCP server).

Please notice that nx_mdns_create() and nx_mdns_enable() are called before nx_dhcp_start().

This is done intentionally for fast DHCP fail demonstration (with BroadcastFilter = ENABLE).

If mDNS starts after DHCP at first look all works ok together, but after a few hours DHCP will try to extend IP lease time but without success because of BroadcastFilter activated by mDNS.

Regards

[Zainulabedeen]

@sssooo I seem to have the exact issue and solution to this problem. Is this solution working fine for you ?

[sssooo]

Yes, it works.

But I can not guarantee that it is 100% correct solution.

Unfortunately there was no help from ST for me.

[STackPointer64]

Hello,

I have escalated the issue to the relevant team for resolution, as it is unusual behavior and should not happen. It is being tracked internally under ticket number CDM0061604.

Best regards,

[STackPointer64 · Accepted solution]

Hello @sssooo,

I just received confirmation from the development team. There was an API change in HAL_ETH_SetMACFilterConfig() in the ETH_MACFilterConfigTypeDef structure for the BroadcastFilter field.

With the new version, the BroadcastFilter field must be set to DISABLE to allow reception of broadcast packets. This is a valid fix, not a workaround.

Best regards,