Azure IoT Hub Library with OpenThread

RE: Azure IoT Hub Library with OpenThread

user76616 — Wed, 11 May 2022 11:53:12 GMT

According to zephyr\subsys\net\lib\dns\resolve.c:1153 getting mapped ipv4 through getaddrinfo will not work.
I am able to use the OpenThread Libraries to resolve DNS requests through the NAT64 interface.

I will be trying to make small modifications to the nRFConnect Azure library to use Openthread sockets to test if connections will actually work.

RE: Azure IoT Hub Library with OpenThread

user109070 — Tue, 10 May 2022 06:07:46 GMT

Hi,

Were you able to make this work? I'd be really interested as I am about to implement a similar solution, so any head-start would be appreciated.

Best regards,

Erik

RE: Azure IoT Hub Library with OpenThread

user76616 — Fri, 29 Apr 2022 13:47:24 GMT

Debugging shows the DNS_EAI_CANCELED is the result of a timeout.

I'm also getting a timeout using the OpenThread specific DNS API's


#include <openthread/dns_client.h>

void ot_dns_response(otError aError, const otDnsAddressResponse *aResponse, void *aContext)
{

	char address_string[OT_IP6_ADDRESS_STRING_SIZE];
	otIp6Address address;
	uint32_t ttl;

	// Fails with error 28
	// [00:00:19.219,787] <inf> net_l2_openthread: State changed! Flags: 0x00000200 Current role: 3
	// [00:00:21.184,112] <err> coap_server: ot_dns_response failed 28

	if (aError == OT_ERROR_NONE)
	{
		uint16_t index = 0;

		LOG_INF("ot_dns_response Success");

		while (otDnsAddressResponseGetAddress(aResponse, index, &address, &ttl) == OT_ERROR_NONE)
		{
			otIp6AddressToString(&address, address_string, sizeof(address_string));
			LOG_INF("ip: %s, TTL:%u ", address_string, ttl);
			index++;
		}
	}
	else
	{
		LOG_ERR("ot_dns_response failed %d", aError);
	}
}

otDnsQueryConfig config;
const otDnsQueryConfig *current_config;
void set_ot_dns_config(void)
{
	otError error;
	current_config = otDnsClientGetDefaultConfig(ot_context->instance);

	memcpy(&config, current_config, sizeof(otDnsQueryConfig));

	config.mNat64Mode = OT_DNS_NAT64_ALLOW;
	config.mRecursionFlag = OT_DNS_FLAG_RECURSION_DESIRED;
	config.mMaxTxAttempts = 2;
	config.mResponseTimeout = 1000;
	config.mServerSockAddr.mPort = 53;

	error = otIp6AddressFromString("FDAA:BB:1::2", &config.mServerSockAddr.mAddress);
	if (error != OT_ERROR_NONE)
		LOG_ERR("otIp6AddressFromString failed %d", error);

	otDnsClientSetDefaultConfig(ot_context->instance, &config);

	current_config = otDnsClientGetDefaultConfig(ot_context->instance);
}

void resolve_ot_dns(void)
{
	otError error;
	error = otDnsClientResolveAddress(ot_context->instance, "ing.nl", &ot_dns_response, ot_context->instance, &config);
	if (error != OT_ERROR_NONE)
	{
		LOG_ERR("ot_dns_response resolve_dns %d", error);
	}
}

Thanks for your suggestions. I'm going to try and increase logging and let you know. Any suggestion to which NET component I should set to debug logging?

RE: Azure IoT Hub Library with OpenThread

user14926 — Fri, 29 Apr 2022 13:38:58 GMT

Can you use the OpenThread specific DNS API used by the ot-cli in the Azure IoT Hub case as well?

If not, you need to debug the application to see where it fails (increase log levels would be a good start), and/or do a on-air sniffer trace of the Thread traffic, to see if the DNS is sent to any destination.

RE: Azure IoT Hub Library with OpenThread

user76616 — Fri, 29 Apr 2022 11:59:51 GMT

Hi,

I've checked by running tcpdump on the RPi OTBR device.

With OT-CLI I see the DNS requests coming through in the tcpdump:

pi@raspberrypi:~ $ sudo tcpdump -vnni wpan0

tcpdump: listening on wpan0, link-type LINUX_SLL (Linux cooked v1), snapshot length 262144 bytes

14:04:33.770137 IP6 (hlim 64, next-header UDP (17) payload length: 36) fd35:ad25:a99f:8c75:a301:6d0:492:8a96.49153 > fdaa:bb:1::2.53: [udp sum ok] 54430+ AAAA? reddit.com. (28)

14:04:33.831836 IP6 (flowlabel 0x67ac1, hlim 64, next-header UDP (17) payload length: 148) fdaa:bb:1::2.53 > fd35:ad25:a99f:8c75:a301:6d0:492:8a96.49153: [udp sum ok] 54430 4/0/0 reddit.com. AAAA 64:ff9b::9765:818c, reddit.com. AAAA 64:ff9b::9765:c18c, reddit.com. AAAA 64:ff9b::9765:18c, reddit.com. AAAA 64:ff9b::9765:418c (140)

I do not see any activity with my resolve_dns() function

RE: Azure IoT Hub Library with OpenThread

user14926 — Wed, 27 Apr 2022 14:53:59 GMT

Hi,

Looks like error code -101 means that the request was cancelled (DNS_EAI_CANCELED). Have you checked with a sniffer trace if the request is actually sent over the air, and if it is sent to the correct address and port (compared to the OT CLI command)?

From an earlier test case, it looks like the request will be cancelled if a local DNS server is not present.

Best regards,
Jørgen

RE: Azure IoT Hub Library with OpenThread

user76616 — Fri, 22 Apr 2022 12:36:26 GMT

Hello Jørgen,

I've tried to set the correct Server, but I am getting an error in the callback.

I configure the DNS and try to resolve when the device connects to the Thread network. Also before the error in dns_result_cb, I get a error "<err> net_otPlat_radio: Error while calling otIp6Send"

void set_dns_config(void)
{
	int ret;
	const char *dns_server = "FDAA:BB:1::2";
	struct dns_resolve_context *dnsctx;

	dnsctx = dns_resolve_get_default();
	ret = dns_resolve_reconfigure(dnsctx, &dns_server, NULL);
}

void dns_result_cb(enum dns_resolve_status status,
				   struct dns_addrinfo *info,
				   void *user_data)
{
	// fails with -101
	// <inf> net_l2_openthread: State changed! Flags: 0x00000064 Current role: 3
	// <err> net_otPlat_radio: Error while calling otIp6Send
	// <inf> coap_server: dns_result_cb Failed: -101
	if (status == 0)
	{
		LOG_INF("dns_result_cb Success");
	}
	else
	{
		LOG_INF("dns_result_cb Failed: %d", status);
	}
	return;
}

void resolve_dns(void)
{
	int ret;
	struct dns_resolve_context *dnsctx;

	dnsctx = dns_resolve_get_default();
	ret = dns_resolve_name(dnsctx,
						   "reddit.com",
						   DNS_QUERY_TYPE_AAAA,
						   NULL,
						   dns_result_cb,
						   NULL,
						   1000);
	if (ret != 0)
	{
		LOG_ERR("resolve_dns %d", ret);
	}
}

Maybe I am missing a configuration, the command in OT CLI example does work.

uart:~$ ot dns resolve reddit.com fdaa:bb:1::2 53 1000 2 1
DNS response for reddit.com. - 64:ff9b:0:0:0:0:9765:c18c TTL:67 64:ff9b:0:0:0:0:9765:818c TTL:67 64:ff9b:0:0:0:0:9765:18c TTL:67 64:ff9b:0:0:0:0:9765:418c TTL:67
Done

RE: Azure IoT Hub Library with OpenThread

user14926 — Thu, 21 Apr 2022 09:24:17 GMT

Hi,

It looks like getaddrinfo() internally calls dns_get_addr_info(), so you may be able to call dns_resolve_init() or dns_resolve_reconfigure() to set the DNS server address.

You may also use the Kconfigs DNS_SERVER_IP_ADDRESSES and CONFIG_DNS_SERVERx to specify the DNS servers used by the DNS resolve library.

Best regards,
Jørgen