Help with TLS Socket Creation on Thingy53 error 109 (ENOTSUP)

[iskrentsbg]

What I've done to fix the Azure authentication issue:

I have inspected the Zephyr code which couldn't successfully complete Azure cognitive services authentication.
I've compared it with your my curl-based C implementation that uses the same endpoint and API key.
I have identified several issues:

TLS socket options failing with error 109 (ENOTSUP)
Possible HTTP request formatting issues
Connection being reset by the server after sending the request

I've tried multiple approaches:

Fixed HTTP request formatting to match curl exactly
Simplified TLS configuration
Tried sending the HTTP headers and empty line separately
Added more debugging

Nothing did work.

The latest log shows:

[00:00:11.880,798] <inf> main: State: COMPLETED
[00:00:11.881,774] <inf> main: SSID: iPhone
[00:00:11.882,659] <inf> main: Getting Azure authentication token...
[00:00:11.883,605] <inf> main: Connecting to westeurope.api.cognitive.microsoft.com...
[00:00:11.884,796] <inf> main: Checking for unhealthy sockets
[00:00:11.885,589] <inf> main: Resolving hostname: westeurope.api.cognitive.microsoft.com
[00:00:12.398,315] <inf> main: Tracking socket 14 in slot 0
[00:00:12.399,139] <wrn> main: Failed to set receive timeout: 109
[00:00:12.400,207] <wrn> main: Failed to set send timeout: 109
[00:00:12.401,214] <inf> main: CA certificate added to TLS credentials
[00:00:12.402,252] <inf> main: Proceeding with TLS connection
[00:00:12.403,228] <inf> main: Connecting to westeurope.api.cognitive.microsoft.com:443...
[00:00:12.644,805] <inf> main: Successfully connected to westeurope.api.cognitive.microsoft.com:443
[00:00:12.646,209] <inf> main: Connected to Azure server, socket fd: 14
[00:00:12.647,186] <inf> main: Sending HTTP request (265 bytes):
[00:00:12.648,101] <inf> main: ------ BEGIN HTTP REQUEST ------
[00:00:12.649,078] <inf> main: POST /sts/v1.0/issuetoken HTTP/1.1
Host: westeurope.api.cognitive.microsoft.com
Ocp-Apim-Subscription-Key: 5Mkszj3yFl2vmbRDchDUHDAOMiZAYmzaLzA508JrnpRYYKBsv4nqJQQJ99BCAC5RqLJXJ3w3AAAYACOGVfQg
Content-Type: application/x-www-form-urlencoded
Content-Length: 0
[00:00:12.652,008] <inf> main: ------ END HTTP REQUEST ------
[00:00:12.653,778] <inf> main: HTTP request sent: 265 bytes
[00:00:12.654,724] <inf> main: Waiting for HTTP response...
[00:00:12.759,216] <wrn> main: Connection reset by peer
[00:00:12.760,009] <err> main: Failed to get TLS error: 109
[00:00:12.760,986] <inf> main: Disconnecting from server, socket 14
[00:00:12.762,054] <inf> main: Untracking socket 14 from slot 0
[00:00:12.763,061] <wrn> main: Socket shutdown failed: 134
[00:00:12.764,160] <inf> main: Socket 14 successfully closed
[00:00:12.865,234] <err> main: Azure authentication failed: -5

Current code

/* TLS configuration in connect_to_server */
if (use_tls) {
ret = setup_tls_credentials();
if (ret < 0) {
LOG_ERR("Failed to set up TLS credentials: %d", ret);
close(sock);
untrack_socket(sock);
zsock_freeaddrinfo(result);
return ret;
}

/* Set TLS options */
int tls_options = TLS_PEER_VERIFY_REQUIRED;
ret = zsock_setsockopt(sock, SOL_TLS, TLS_PEER_VERIFY, &tls_options, sizeof(tls_options));
if (ret < 0) {
LOG_ERR("Failed to set TLS peer verification: %d", errno);
close(sock);
untrack_socket(sock);
zsock_freeaddrinfo(result);
return -EIO;
}

/* Set TLS certificate */
struct tls_credential cert = {
.type = TLS_CREDENTIAL_CA_CERTIFICATE,
.tag = CA_CERT_TAG
};
ret = zsock_setsockopt(sock, SOL_TLS, TLS_CREDENTIAL, &cert, sizeof(cert));
if (ret < 0) {
LOG_ERR("Failed to set TLS certificate: %d", errno);
close(sock);
untrack_socket(sock);
zsock_freeaddrinfo(result);
return -EIO;
}

LOG_INF("Proceeding with TLS connection");
}

/* HTTP request sent in two parts in get_azure_auth_token */
const char *http_headers =
"POST /sts/v1.0/issuetoken HTTP/1.1\r\n"
"Host: westeurope.api.cognitive.microsoft.com\r\n"
"Ocp-Apim-Subscription-Key: 5Mkszj3yFl2vmbRDchDUHDAOMiZAYmzaLzA508JrnpRYYKBsv4nqJQQJ99BCAC5RqLJXJ3w3AAAYACOGVfQg\r\n"
"Content-Type: application/x-www-form-urlencoded\r\n"
"Content-Length: 0\r\n";

/* Empty line to separate headers from body */
const char *empty_line = "\r\n";

/* Send headers first */
int sent = zsock_send(sock, http_headers, headers_len, 0);

/* Add small delay to ensure headers are processed */
k_sleep(K_MSEC(100));

/* Now send the empty line separately */
sent = zsock_send(sock, empty_line, 2, 0);

/* print_tls_error_info function to debug TLS issues */
void print_tls_error_info(int sock)
{
int err;
socklen_t optlen = sizeof(err);

if (getsockopt(sock, SOL_TLS, TLS_ERROR_OPTION, &err, &optlen) == 0) {
LOG_ERR("TLS error code: %d", err);

switch (err) {
case MBEDTLS_ERR_SSL_CONN_RESET:
LOG_ERR("Connection reset by peer");
break;
case MBEDTLS_ERR_SSL_BAD_HS_SERVER_HELLO:
LOG_ERR("Bad server hello message");
break;
/* Other error cases... */
}
}
}