[SNMP4J] Negative Request IDs

[robert.m.dabell at L-3com.com]

Frank,
After a little more research I've read that because the request ID is
specified as an Integer32 that the agent should be able to handle request
IDs that are from -2^31 to (2^31)-1.  Therefore, I can only conclude that
there is a bug in the agent if a request is negative.  I modified the
getBERPayloadLengthPDU function to fix this bug by replacing this line

Integer32 i32 = new Integer32((requestID.getValue() > 0) ?
	requestID.getValue() : 0xFFFFFFFF);

with 

Integer32 i32 = requestID;

in PDU.java.

I've tested this and it fixes my problems with negative request IDs.

Mark DaBell

-----Original Message-----
From: snmp4j-bounces at agentpp.org [mailto:snmp4j-bounces at agentpp.org]On
Behalf Of robert.m.dabell at L-3com.com
Sent: Monday, October 24, 2005 11:40 AM
To: SNMP4J at agentpp.org
Subject: [SNMP4J] Negative Request IDs


Frank,
First of all, I think SNMP4J is great.  It has helped me out a lot.

Is there a SNMP rule that states that Request IDs cannot be negative?  I
have an agent written with SNMP4J-Agent with a non-SNMP4J Manager that is
sending negative request IDs that is causing a buffer overflow in the agent
when it is encoding the last bytes of the buffer.  I have suspected the
request ID because with positive request IDs are used it works fine.  I have
traced the root of the problem to the getBERPayloadLengthPDU() function
call.

Integer32 i32 = new Integer32((requestID.getValue() > 0) ?
requestID.getValue() : 0xFFFFFFFF);
    length += i32.getBERLength();

If the request id is negative then its length is set to 1 because the
BERLength of 0xFFFFFFFF(-1) is 1.  This throws off the buffer position if
the request ID is negative and takes up more than 1 byte of space.  If the
request IDs cannot be negative then I think there should be a least a log
message that negative req. IDs are not supported and I'll find a work
around.  If they can be negative then this is a bug. 

Mark DaBell
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