CHOICE_decode_aper result was wrong when decoding an extension CHOICE

[tangzhikun]

I am decoding an extension CHOICE, but the CHOICE_decode_aper result was wrong. The result was corrected after that changes made.

-if (ct && ct->upper_bound >= ct->lower_bound) {
-value = aper_get_nsnnwn(pd, ct->upper_bound - ct->lower_bound + 1);
+value = uper_get_nsnnwn(pd);
if(value < 0) ASN__DECODE_STARVED;
value += specs->ext_start;
if((unsigned)value >= td->elements_count)
    ASN__DECODE_FAILED;
-}

I'm an asn noob, it is the right way to fix it? or can you tell me how to fix it?

[mouse07410]

is this the right way to fix it?

Offhand, no it isn't - because a) you're presumably decoding an APER PDU, but you're switching to UPER decoder for pd; and b) the code was supposed to validate and ensure that the value falls within the defined range (resides between ct->lower_bound and ct->upper_bound). You merely disposed of all those checks - this does not look good.

What is the value (original, and decoded in both cases), and what does its encoding look like? Also, what happens if you try to decode that PDU on OSS Nokalva ASN.1 playground?

[mouse07410]

Closing by #127