TLS connections using OpenThread/Matter

[FHFS]

Hi everyone,

I am working with a nrf52840 and want to make use of the Azure IoT Hub.

I've checked out the Azure IoT Hub Library that exists for the nrf91, which uses the MQTT library from zephyr. The MQTT library creates zephyr sockets with mbedtls options.

I have set up a OpenThread network with a BorderRouter and other device, I can resolve hostnames through the nat64 interface and set up tcp connections to the internet.

I tried using the zephyr sockets but am unable to create a socket that does not timeout. I also cannot use getaddrinfo to resolve hostnames.

I am able to use the OpenThread TCP api to create connections but I cant create TLS connections with these.

Should I be able to use the Zephyr sockets with a OpenThread network? Or do I need to find another way

[jwhui]

Zephyr's getaddrinfo probably does not (yet) integrate with Thread's DNS services. For example, Thread defines specific mechanisms for discovering the DNS configuration info.

I believe you should be able to use Zephyr sockets with OpenThread, but I am unsure why you are not able to establish TLS/TCP connections. Maybe @LuDuda can provide some insight.

[rlubos]

@FHFS I've now noticed that you rely on the default net_buf/pkt count which is pretty low. I did some testing and apparently the defaults are too small for OpenThread + TCP combination (I was able to reproduce the issue you observe, the TCP client kept retransmitting the SYN packet). Try increasing the following configs in your prj.conf file (below values worked for me):

CONFIG_NET_PKT_RX_COUNT=8
CONFIG_NET_PKT_TX_COUNT=8
CONFIG_NET_BUF_RX_COUNT=32
CONFIG_NET_BUF_TX_COUNT=32

[FHFS]

I've tested the echo server/client samples. These indeed do work.
I've set up one nRF as server and one as client, and they are sending tcp packets.
However when I add in my Border Router, it fails. could the problem be in the RCP?

@rlubos I've added these settings to my prj.conf, but the nRF has the same timeout trying to tcp connect to the Border Router

[rlubos]

could the problem be in the RCP?

I don't want to exclude any option, but I doubt RCP is a problem here, it shouldn't make a difference whether it forwards TCP or UDP.

I've added these settings to my prj.conf, but the nRF has the same timeout trying to tcp connect to the Border Router

Well, if increasing buffers didn't help, then I'm out of ideas for the moment on where the problem is.

[FHFS]

@rlubos starting over with the echo client works. I can now TCP connect to the border router, using that example.

Thanks everyone for your help!

[FHFS]

Also I was creating sockets in event handlers, this worked for the Openthread TCP api's but not for the zephyr sockets.
Because of the echo_client example, I saw they used semaphores to resume the main thread when the connected event occurs.