[lwip-users] mDNS example with an OS?

[groups]

Hello,

I’ve been trying to get my mind around getting the mDNS system working with an RTOS. I’m working with an STM32F7 with ST’s 2018 version of LwIP and FreeRTOS, but my final target is RTEMS.

I’ve tried to go through the test code in contrib-2.1.0, and cribbed the basic flow, but I haven’t been able to get mDNS working on an RTOS.

What I’d like to do is get a service going under FreeRTOS and announce it using mDNS. 

So far I’ve been able to get mDNS to announce a service using a big loop model program, and I’ve been able to get a simple TCP echo server going with FreeRTOS. But when I put them together, netconn_accept in the echo server never returns when I connect to the port. Get rid of the mDNS calls and the echo server works nicely.

Simple? It sounds like it, but I haven’t found the appropriate programming idiom to get it working.

I think there’s a hint in the docs. In pitfalls, it says “But “raw” APIs functions must ONLY be called from TCPIP thread.“  Okay, looking through the mDNS code, it uses a lot of raw calls to UDP functions, so I must arrange for the tcpip thread to do the calls for me, but I can’t figure out how.

Can someone please point me at an example of using mDNS responder in an RTOS environment so I can pull it apart and see what I’m doing wrong?

Thank you very much for your help,

Andrei (from The Great White North)