DLMS COSEM - MSP430 - Error when reading more than 127 elements

Alan Casinelli

Other Parts Discussed in Thread: AES-128

Hello everyone,

I found a bug in the DLMS COSEM library when reading an object with more than 127 elements.

For example when setting 128 elements in config.c and then sending the request to read all the objects (C0 01 81 00 0F 00 00 28 00 00 FF 02 00) the reply is:
C4 01 81 00 01 80 whereas it should have been C4 01 81 00 01 81 80

Thanks for your help.

over 7 years ago

0 Ryan Brown1 over 7 years ago

TI__Guru**** 202226 points

Hello Alan,

I would not state this as a bug but rather a limitation of the software, 128 elements is conveniently 2^7 and this maximum number of elements allowed could have something to do with the AES128-based authentication mechanism used. Please stay within the 127-element boundary.

Regards,
Ryan

0 Chander G over 7 years ago

TI__Intellectual 2270 points

Hi Alan,
Could you pls send the exact definition of your object in config.c. As per my understanding, I took care of different sizes in the stack.
Regards,
Chander

0 Alan Casinelli over 7 years ago in reply to Chander G

Intellectual 280 points

Hi Chander,

Sorry for the late reply. The objects are all part of the object_list[] array.
I am out of the office until next monday so I cannot give you the exact object definition, but, just to give an idea, the object_list is made of 128+ elements like

{ASSOC_PC_MR_US_MS, CLASS_ID_CLOCK, 0, { 0, 0, 1, 0, 0, 255}, 9, clock_attrs, 6, clock_methods},
{ASSOC_PC, CLASS_ID_ASSOCIATION_LN, 0, { 0, 0, 40, 0, 0, 255}, 8, ln_40_attrs_NS_Mndtry, 4, ln_40_methods},
{ASSOC_MR_US, CLASS_ID_REGISTER, 0, { 1, 0, 31, 7, 0, 255}, 3, Obj_I_R, 0, NULL},

0 IvanKrizanic over 7 years ago in reply to Chander G

Prodigy 75 points

My problem is similar, I have object list with over 127 objects and library returns:

C4 01 81 00 01 FD

which gurux won't accept (kalkitech accepts it with no problems). But when reading over 255 objects object counter rolls over to 0x00 and reply looks like there are just a few objects instead of over 256:

C4 01 81 00 01 05.

Is this really linked with AES-128 encryption like the Ryan said?

0 Chander G over 7 years ago in reply to IvanKrizanic

TI__Intellectual 2270 points

Yes I think the possibility of having number of objects > 127 have been ignored while developing the library. The fix to this should not take a long time. I am on business travel right now. I will fix this soon and revert back to you guys.

0 IvanKrizanic over 7 years ago in reply to Chander G

Prodigy 75 points

I think it's not problematic just for having more than 127 objects in object list, but also in every array in ASN.1 notation.

Length octets. There are two forms: short (for lengths between 0 and 127), and long definite (for lengths between 0 and 2^1008 -1).

Short form. One octet. Bit 8 has value "0" and bits 7-1 give the length.

Long form. Two to 127 octets. Bit 8 of first octet has value "1" and bits 7-1 give the number of additional length octets. Second and following octets give the length, base 256, most significant digit first.

0 IvanKrizanic over 7 years ago in reply to Chander G

Prodigy 75 points

Is there any estimate on when this bug will be fixed? I noticed that the library has been removed from its page and can't be downloaded any more.

0 Chander G over 7 years ago in reply to IvanKrizanic

TI__Intellectual 2270 points

Hi Ivan,

Could you pls leave your mail ID so that I can contact you offline and provide you with a alpha release of modified stack?

Regards,

Chander

0 IvanKrizanic over 7 years ago in reply to Chander G

Prodigy 75 points

Yes, my e-mail is ivan.krizanic at riz.hr

0 Alan Casinelli over 7 years ago in reply to Chander G

Intellectual 280 points

Hi Chander,

Can you send me the alpha version too at: alan.casinelli 'at' cptengineering.it

Thanks

0 IvanKrizanic over 7 years ago in reply to Alan Casinelli

Prodigy 75 points

I wouldn't have a lot of hope regarding that as I haven't received anything and since moved on to better supported solutions.

0 Alan Casinelli over 7 years ago in reply to IvanKrizanic

Intellectual 280 points

Hopefully, someone will read this post and at least update us on the bug fixing stage.

0 Chander G over 7 years ago in reply to Alan Casinelli

TI__Intellectual 2270 points

Hi Alan,

I have sent an SLA for your acceptance at your email ID. Once you send the acceptance mail. I will release the library to you.

Regards,

Chander

0 Alan Casinelli over 7 years ago in reply to Chander G

Intellectual 280 points

Hi Chander,
I have received your application, but I'm unable to merge it with my application because the data model used to build the library (medium) is different from the one I used for my application (large).
Is it possible for you to send me the same version of the library with the data_model and code_model set to large?
I have also sent you an email regarding this issue.

Thanks again for your help.
Best Regards,
Alan

0 Chander G over 7 years ago in reply to Alan Casinelli

TI__Intellectual 2270 points

Hi Alan,

I have provided the updated library.

Regards,

Chander

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DLMS COSEM - MSP430 - Error when reading more than 127 elements