Ethereal-users: Re: [Ethereal-users] Server Response times

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From: Guy Harris <gharris@xxxxxxxxx>
Date: Sat, 21 Jun 2003 02:19:46 -0700
On Sat, Jun 21, 2003 at 06:12:35PM +1000, Ronnie Sahlberg wrote:
> One problem with the SNMP dissector is that most of the SNMP data that is
> displayed are not dissected by hand-written code but instead through an
> extenal library.

Actually, the data is *dissected* with code from Ethereal (asn1.c);
however, it's *interpreted*, beyond the "this is an ASN.1 {INTEGER,
OCTET STRING, ...}" level, by an external library, namely the UCD
SNMP/NET-SNMP library.

Ethereal could put values extracted with asn1_XXX_decode routines into
the protocol tree as filterable fields (in fact, you just checked in a
change to put the request ID into the tree as a filterable field);
however, it couldn't put the variable bindings into the protocol tree as
anythng more than something such as "snmp.vb_oid" for object IDs and
"snmp.vb_value_int", "snmp.vb_value_octet_string", etc. for values.

> However (if i remember correctly) a lot of the payload is handled by the
> external asn library in teh same was as snmp payload is and thus it is
> difficult to get to it.

The ASN.1 library is, as noted, internal, not external (asn1.c).