Calling socket connect() triggers errno=95

[Loren Rogers]

Hello,

I am offloading sockets in config.  I instantiate a socket, set the send/recv timeouts, and then call connect().  It's returning a 95 which is EOPNOTSUPP.  I was able to step via debug all the way down to a nrf_connect().  But that was it.

Anyone have any ideas of what I'm doing wrong?

/Loren

[Charlie]

Hi Loren,

Is this a customize board? Did you test with a TLS connection? If the connection is lost during data transmission, there can be an error thrown (for TLS, it is normally -95). Could you check if the signal strength (via AT+CESQ) is good when this occurs?

If the problem still exists, could you provide your current modem firmware version and a modem trace when the failure happens? 

Best regards,

Charlie

[Loren Rogers]

Hi Charlie,

It is the standard nrf9160 dk board.  I'm not going to lie.  I am totally lost and pretty overwhelmed.  Especially when it comes to what CONFIG options I need.  All I want is an application that will create and connect to a TLS socket (443) to ANY server I choose (not just nRF Cloud) and be able to call the http_client_req() method with my particular REST method and an url.  I come from the iOS/Android world where there are libraries that do this automatically.  Could you please let me know what CONFIG options I need and some source code on how to set this up?

The other thing that I find infuriating is that I can't seem to reliably debug this thing.  I'll tap 'step over' and it jumps to some other place I have no clue about.  And I believe I've set the NO_OPTIMIZATIONS configuration but I still can't see some local variables.

Thanks!

/Loren

[Loren Rogers]

trace-2021-09-30T18-56-20.088Z.bin

[Loren Rogers]

I just found something interesting that could be a problem: I ran Postman on 2 separate servers.  Both servers use TLS-ECDHE-ECDSA-WITH-AES-256-GCM-SHA384 for the cipher.  I noticed that Nordic does not support this.  It does support TLS-ECDHE-ECDSA-WITH-AES-256-CBC-SHA384. (CBC vs. GCM).  Would this cause what I am seeing? Also could we add our own 'TLS-ECDHE-ECDSA-WITH-AES-256-CBC-SHA384' encryption somehow?

[Charlie]

Hi Loren, 

This trace file has no meaningful data

Did you see the following printout from LTE Link Monitor?

Best regards,

Charlie

[Charlie]

Hi Loren,

nRF9160 modem can only support limited TLS Cipher suites, unsupported cipher suites cannot be used, please modify your server setting first.

Best regards,

Charlie

[Loren Rogers]

After an inadvertent reboot of my PC, I have been able to capture traces now.  I'm uploading a wireshark trace to publicapis.org with a rejection (95) because the server didn't support any of my ciphers. I did manage to find a server that would accept one of nrf9160 ciphers.

Because of internal network issues, I am unable to attempt a connection to our server to see if our server would reject the nrf9160 ciphers.  That being said, how hard would it be to add GCMtrace-2021-10-04T19-04-12.146Z.pcapng-based cipher support to the nrf SDK?  I looked at Zephyr API's and THEY support GCM-based ciphers.

[Charlie]

Hi Loren,

The nRF9160 Modem firmware v1.3.1 is going to be released in one week and it will add support to TLS-ECDHE-ECDSA-WITH-AES-256-GCM-SHA384 cipher suite. Please pay attention to this page.

Best regards,

Charlie

[Loren Rogers]

Hi Charlie,

I've managed to get around this problem.  However I have a new problem and I was wondering if you could please give me some assistance.

New ticket is here: devzone.nordicsemi.com/.../recv-returning-0

[Charlie]

Hi Loren,

Glad to hear your good news. My colleague will help you with that ticket. 

Happy work! :-)

Best regards,

Charlie