Re: snmp payload compression

[Juergen Schoenwaelder <schoenw@ibr.cs.tu-bs.de>]

>>>>> Robert Story writes:

>> 5.2.1 ODC Algorithm
>> 
>> 3.  Truncation of OIDs (which may shorten or enlarge OIDs).  A
>> truncation, which may only appear at the end, is encoded as
>> follows:

Robert> May appear only at the end of what? I assume you mean the
Robert> compressed OID?  

Correct. I will make the clear in the next update.

Robert> Does this imply that the first two can appear in any order?

Yes.

Robert> Can you have multiple occurances of either of the first two?

Yes.

Robert> Even if each can only occur once, there is still no indication
Robert> of how many of the 3 types will occur. So when decoding, how
Robert> do you know if the byte after the first compression type is
Robert> another compression type or the start of the value?

while (/* there are more bytes in the compressed PDU */) {
    if (first_byte & 0x80) {
       /* do range substitution */
    } else if (! last byte) {
       /* do single substitution */
    } else {
       /* do truncation */
    }
}

Perhaps we should just put an implementation into the appendix...

/js