#1853 Getbulk maximum message size
Software version number: Net-SNMP 5.3.0.1
Operating System: Linux zar03-eng-401.mot.com 2.6.8-3-686 #1 Sat Jul 15 10:32:25 UTC 2006 i686 GNU/Linux
Problem description:
In a bulkGet request, when the msgMaxSize of the originator is exceeded, Net-SNMP agent doesn't respond according to the RFC 3416 (section 4.2.3):
" (1) If the size of the message encapsulating the Response-PDU containing the requested number of variable bindings would be greater than either a local constraint or the maximum message size of the originator, then the response is generated with a lesser number of variable bindings. "
The response is not truncated, as RFC requests.
To reproduce the problem, send a getBulk request with many repetitions and a small msgMaxSize in the request PDU.
See mail attached with the discussion of the solution in the net-snmp-coders list.
Mail chain discussing the solution for this bug
As a practical work-around for this problem, could we disable session msgMaxSize checking and just allow net-snmp to respond with an oversized message?
This of course in not RFC compliant, but it is better than just ignoring a request.
At one point in a discussion long ago, Wes assumed it worked this way: https://www.mail-archive.com/net-snmp-users@lists.sourceforge.net/msg09581.html
Furthermore, this report (http://www.ietf.org/iesg/implementation/report-rfc2026.html) says "Most implementations were found to have relaxed range checking on received values for msgID and msgMaxSize ...". This suggests that many requesters will be able to deal with an oversized response.