Hi,
The problem that I was facing was that
snmpwalk goes in an infinite loop after displaying the table in my mib, instead
of ending successfully. The same code workes in net-snmp-5.1, and goes in an
infinite loop after upgrading to net-snmp-5.2.2.
I was able to trace the problem to a code
change related to sparse table.
The problem lies in the
agent/helpers/table.c file, in the function table_helper_handler. In
net-snmp-5.2.2 an additional function sparse_table_helper_handler is called,
which checks the request->requestvb->type. If it is ASN_NULL, it sets it
to ASN_PRIV_RETRY, so net-snmp goes in an infinite loop trying to get the next
value after the end of the table which does not exist. ( Note that if I return
without setting anything after I reach the end of table,
request-requestvb->type gets set to ASN_NULL by default, and so we enter this
infinite loop ).
So, instead of returning without setting
anything when I reach the end of table, if I return SNMP_NOSUCHOBJECT when I get
the get_next request for the last element in the table, the
sparse_table_helper_handler replaces it with ASN_NULL and so net-snmp then
correctly goes to the next registered mib.
netsnmp_table_build_result(reginfo,
requests,
table_info, SNMP_NOSUCHOBJECT,
(u_char*) &x,
sizeof(x));
table_info, SNMP_NOSUCHOBJECT,
(u_char*) &x,
sizeof(x));
So basically, for snmpwalk to work
correctly for my mib in net-snmp-5.2.2 without going into an infinite loop at
the end, I need to return SNMP_NOSUCHOBJECT after reaching the end of the table.
After adding this code, now the snmpwalk works even in net-snmp-5.2.2
Is this a bug in net-snmp-5.2.2 or is it by design ? Is this an
additional requirement for using net-snmp-5.2.2 to return SNMP_NOSUCHOBJECT
?
Regards,
Amita
From: [EMAIL PROTECTED] on behalf of Amita Mhaskar
Sent: Mon 4/10/2006 6:00 AM
To: net-snmp-users@lists.sourceforge.net
Subject: snmpwalk does not understand the END of a Table for my MIB
Hi,
I am using net-snmp-5.2.2 linux 4.2. I have an
enterprise MIB which contains 2 tables. When I give snmpwalk command for a
table, it correctly returns all the entries for the table, but timesout in the
end. From the logs enabled for snmpd, I see that snmpd keeps sending a get-next
request for the last entry in the table, and it keeps getting NOSUCHINSTANCE,
but it does not go on to the next registered part in the MIB and does not
realize that the table is complete, and so the snmpwalk command timesout in the
end.
My MIB has the following :
18359(enterprises).1(ipSanMib).1(objects).1(realm).1(realmTable).1(realmEntry).1(realmIndex)
to
18359(enterprises).1(ipSanMib).1(objects).1(realm).1(realmTable).1(realmEntry).22(realmSystemTime)
18359(enterprises).1(ipSanMib).1(objects).1(realm).1(realmTable).1(realmEntry).22(realmSystemTime)
18359(enterprises).1(ipSanMib).1(objects).2(alert).1(alertTable).1(alertEntry).1(alertIndex)
to
18359(enterprises).1(ipSanMib).1(objects).2(alert).1(alertTable).1(alertEntry).9(alertDescription)
18359(enterprises).1(ipSanMib).1(objects).2(alert).1(alertTable).1(alertEntry).9(alertDescription)
From the snmpd.log
file:
handler:calling: calling handler table for mode GETNEXT
trace: table_helper_handler(): table.c, 184:
helper:table:req: Got request for handler table: base oid:SNMPv2-SMI::enterprises.18359.1.1.1.1
SNMPv2-SMI::enterprises.18359.1.1.1.1.1.22.1 ===> (realmSystemTime)
:
trace: table_helper_handler(): table.c, 184:
helper:table:req: Got request for handler table: base oid:SNMPv2-SMI::enterprises.18359.1.1.1.1
SNMPv2-SMI::enterprises.18359.1.1.1.1.1.22.1 ===> (realmSystemTime)
:
:
handler:returned: handler IntransaIpSanAlert returned 0
sparse: retry for NOSUCHINSTANCE
trace: netsnmp_call_handler(): agent_handler.c, 426:
handler:returned: handler table returned 0
trace: handle_getnext_loop(): snmp_agent.c, 2834:
results: getnext results, before next pass:
trace: handle_getnext_loop(): snmp_agent.c, 2837:
results: trace: sprint_realloc_by_type(): mib.c, 1977:
sparse: retry for NOSUCHINSTANCE
trace: netsnmp_call_handler(): agent_handler.c, 426:
handler:returned: handler table returned 0
trace: handle_getnext_loop(): snmp_agent.c, 2834:
results: getnext results, before next pass:
trace: handle_getnext_loop(): snmp_agent.c, 2837:
results: trace: sprint_realloc_by_type(): mib.c, 1977:
SNMPv2-SMI::enterprises.18359.1.1.1.1.1.22.1 is the last entry in the
table.
Fot the normal mibs like system, I saw that after the last entry for
system: SNMPv2-MIB::sysORUpTime.9 = Timeticks: (2204) 0:00:22.04, the getnext
for this goes on to IF-MIB and snmpwalk knows that it has received the complete
output for "system".
race: snmp_pdu_parse(): snmp_api.c,
4366:
dumph_recv: VarBind
trace: snmp_parse_var_op(): snmp.c, 166:
dumph_recv: Name
dumpx_recv: 06 0A 2B 06 01 02 01 01 09 01 04 09
dumpv_recv: ObjID: SNMPv2-MIB::sysORUpTime.9
trace: snmp_pdu_parse(): snmp_api.c, 4375:
dumph_recv: Value
GETNEXT message
-- SNMPv2-MIB::sysORUpTime.9
dumph_recv: VarBind
trace: snmp_parse_var_op(): snmp.c, 166:
dumph_recv: Name
dumpx_recv: 06 0A 2B 06 01 02 01 01 09 01 04 09
dumpv_recv: ObjID: SNMPv2-MIB::sysORUpTime.9
trace: snmp_pdu_parse(): snmp_api.c, 4375:
dumph_recv: Value
GETNEXT message
-- SNMPv2-MIB::sysORUpTime.9
:
:
trace: netsnmp_add_varbind_to_cache(): snmp_agent.c, 1901:
snmp_agent: tp->start SNMPv2-MIB::sysORUpTime, tp->end SNMPv2-MIB::sysOREntry.5,
snmp_agent: tp->start SNMPv2-MIB::sysORUpTime, tp->end SNMPv2-MIB::sysOREntry.5,
:
:
trace: netsnmp_add_varbind_to_cache(): snmp_agent.c, 1901:
snmp_agent: tp->start SNMPv2-MIB::sysOREntry.5, tp->end IF-MIB::ifNumber,
snmp_agent: tp->start SNMPv2-MIB::sysOREntry.5, tp->end IF-MIB::ifNumber,
What change do I need to do so that I can get a snmpwalk successfully
completed instead of a timeout, after it has finished displaying all the
values?
Is the mail chain : "Re: Repost: Retrieving scalar objects" from the
archives related to this problem?
Thanks & Regards,
Amita
