[feature]: allow concat of non-VSA attributes

[sdktr]

What type of feature is needed?

Small feature, a tweak to existing behavior

What is the feature?

In 701a48d the concat flag on radius attributes was introduced. It is allowed for non-VSA attributes only. We have Nokia / Alcatel VSA attribute (Alc-Nas-Filter-Rule-Shared) that support concatenation of values within an attribute as well.

Because a change in the dictionary to include the 'concat' flag is not allowed, as a workaround, we now concat the values using a python module. Including overflow to more attributes if the length exceeds 240(-ish?) bytes.

This custom code would be unneeded if the concat of non-VSA were to be allowed/fixed by Freeradius natively. Can this restriction be lifted from the code base?

if (vendor && flags.concat) {
    fr_strerror_printf("VSAs cannot have the \"concat\" flag set");
    return -1;
}

[alandekok]

The issue is not simple. There will have to be new code written to both split VSAs on output, and to concatenate them on input.

We'll leave this open as a "todo", but it's hard to find time to fix it right now.