ASPA result when ASPA table is empty? (disconnected or 0 entries supplied)

[Jeroen Massar]

Hi,

I was checking the ASPA possibilities, and the is_upstream option of aspa_check definitely is confusing.
The downstream/upstream variant also, as the logic seems reverse to what one would expect.

A better example would be rather welcome, though, I think I have it correct now with details from the list.



It would also be useful if we could do something like we can do for RPKI:

        print roa_check(rpki4, 84.205.83.0/24, 12654) = ROA_UNKNOWN;
        print roa_check(rpki4, 93.175.146.0/24, 12654) = ROA_VALID;
        print roa_check(rpki4, 93.175.147.0/24, 12654) = ROA_INVALID;

and that we could run a similar:
        print aspa_check(aspas, "54874 970", false) = ASPA_INVALID;

Currently though there is no datatype that would allow one to provide the BGP path thus that test would not be possible.




But, I do think there might be a bug (though I might just understand the whole thing wrong).

If we simply define:

```
aspa table aspas;
```

and then call a `aspa_check(aspas, ...., ...)` then I sometimes receive a ASPA_VALID back, especially for paths with only 1 ASN.

This, while that table is really empty.

Checking the code:
https://gitlab.nic.cz/labs/bird/-/blob/master/nest/rt-table.c#L356

There is a !found for the upstream edition, but in the end, the logic does not account for a empty ASPA table, which could simply be because one lost the connection to the RTR that supplies is (or stayrtr not providing currently any entries...)

Which might cause an ASPA_VALID to come out, even though not a single ASPA entry has been defined and as there are no entries the path cannot be 'surely valid'... should that situation not be ASPA_UNKNOWN?

Maybe a meree check if 'tab' is empty at the top would be sufficient to determine that it will always be unknown as we have no positive or negative entries?

net_roa_check has a 'anything' variable to cover that situation it seems, which causes ROA_INVALID : ROA_UNKNOWN which is the correct way IMHO. (correct and nice use of inline macros there btw :) )

Greets,
 Jeroen