RE: Managing multiple instances of a MIB

This fix didn't work for me. Infact, after applying this patch, snmpd
process froze at the following location. The stack trace looks a bit
weird though. According to the stack trace the process got stuck in a
call to free().

(gdb) run -r -f -C -c /home/riju/tools/scripts/snmpd.conf -d -r -Lo -V
-x 127.0.0.1:7005 -Dagentx udp:8765
Starting program: /tmp/snmp/sbin/snmpd -r -f -C -c
/home/riju/tools/scripts/snmpd.conf -d -r -Lo -V -x 127.0.0.1:7005
-Dagentx udp:8765
agentx/subagent: init_subagent sess 09fc48a8
agentx_register_app_config_handler: registering .conf token for
"agentxsocket"
agentx_register_app_config_handler: registering .conf token for
"agentxperms"
agentx_register_app_config_handler: registering .conf token for
"agentxRetries"
agentx_register_app_config_handler: registering .conf token for
"agentxTimeout"
Turning on AgentX master support.
agentx/master: initializing...
agentx/master: initializing... DONE
read_config_store open failure on /var/net-snmp/snmpd.conf
read_config_store open failure on /var/net-snmp/snmpd.conf
read_config_store open failure on /var/net-snmp/snmpd.conf
read_config_store open failure on /var/net-snmp/snmpd.conf
read_config_store open failure on /var/net-snmp/snmpd.conf
read_config_store open failure on /var/net-snmp/snmpd.conf

Sending 44 bytes to UDP: [127.0.0.1]:8764
0000: 30 2A 02 01 00 04 06 70 75 62 6C 69 63 A4 1D 06
0*.....public...
0016: 0A 2B 06 01 04 01 BF 08 03 02 0A 40 04 C0 A8 03
..+.........@....
0032: F4 02 01 00 02 01 00 43 01 0B 30 00 .......C..0.


Sending 95 bytes to UDP: [127.0.0.1]:8764
0000: 30 5D 02 01 01 04 06 70 75 62 6C 69 63 A7 50 02
0].....public.P.
0016: 04 06 22 E2 0F 02 01 00 02 01 00 30 42 30 0D 06
..."........0B0..
0032: 08 2B 06 01 02 01 01 03 00 43 01 0B 30 17 06 0A
..+.......C..0...
0048: 2B 06 01 06 03 01 01 04 01 00 06 09 2B 06 01 06
+...........+...
0064: 03 01 01 05 01 30 18 06 0A 2B 06 01 06 03 01 01
......0...+......
0080: 04 03 00 06 0A 2B 06 01 04 01 BF 08 03 02 0A
......+.........

NET-SNMP version 5.2.1

Received 80 bytes from TCP: [127.0.0.1]:33150
0000: 01 01 00 00 00 00 00 00 00 00 00 00 26 E9 C3 0C
.............&...
0016: 3C 00 00 00 00 00 00 00 05 04 00 00 01 00 00 00
<...............
0032: 88 1F 00 00 03 00 00 00 02 00 00 00 0A 00 00 00
.................
0048: 19 00 00 00 4E 65 74 2D 53 4E 4D 50 20 41 67 65 ....Net-SNMP
Age
0064: 6E 74 58 20 73 75 62 2D 61 67 65 6E 74 00 00 00 ntX
sub-agent...

agentx/master: handle pdu (req=3D0xcc3e926,trans=3D0x0,sess=3D0x0)
agentx/master: open 0xa04abb8
agentx/master: opened 0xa05b668 =3D 8 with flags =3D a0
agentx/master: send response, stat 0 =
(req=3D0xcc3e926,trans=3D0x0,sess=3D0x0)
agentx_build: packet built okay

Sending 88 bytes to TCP: [127.0.0.1]:33150
0000: 01 12 00 00 08 00 00 00 00 00 00 00 26 E9 C3 0C
.............&...
0016: 44 00 00 00 C0 0A 00 00 00 00 00 00 04 00 00 00
D...............
0032: 05 04 00 00 01 00 00 00 88 1F 00 00 03 00 00 00
.................
0048: 02 00 00 00 0A 00 00 00 19 00 00 00 4E 65 74 2D
.............Net-
0064: 53 4E 4D 50 20 41 67 65 6E 74 58 20 73 75 62 2D SNMP AgentX
sub-
0080: 61 67 65 6E 74 00 00 00 agent...


Received 52 bytes from TCP: [127.0.0.1]:33150
0000: 01 03 08 00 08 00 00 00 00 00 00 00 27 E9 C3 0C
.............'...
0016: 20 00 00 00 0D 00 00 00 73 6C 73 61 6C 70 68 61
........slsalpha
0032: 3A 37 38 38 38 00 00 00 00 00 00 00 01 00 00 00
:7888...........
0048: 00 00 00 00 ....

agentx/master: handle pdu (req=3D0xcc3e927,trans=3D0x0,sess=3D0x8)
agentx/master: in register_agentx_list
agentx/master: duplicate registration
agentx/master: send response, stat 263
(req=3D0xcc3e927,trans=3D0x0,sess=3D0x8)
agentx_build: packet built okay

Sending 40 bytes to TCP: [127.0.0.1]:33150
0000: 01 12 00 00 08 00 00 00 00 00 00 00 27 E9 C3 0C
.............'...
0016: 14 00 00 00 C0 0A 00 00 07 01 00 00 05 00 00 00
.................
0032: 01 00 00 00 00 00 00 00 ........


Program received signal SIGINT, Interrupt.
0x00d76304 in malloc_consolidate () from /lib/tls/libc.so.6
(gdb) where
#0 0x00d76304 in malloc_consolidate () from /lib/tls/libc.so.6
#1 0x00d7619d in _int_free () from /lib/tls/libc.so.6
#2 0x00d75018 in free () from /lib/tls/libc.so.6
#3 0x00a7830b in _sess_read (sessp=3D0xa03edc0, fdset=3D0xbfff9360)
at snmp_api.c:5574
#4 0x00a78594 in snmp_sess_read (sessp=3D0xa03edc0, fdset=3D0xbfff9360)
at snmp_api.c:5625
#5 0x00a7780e in snmp_read (fdset=3D0xbfff9360) at snmp_api.c:5260
#6 0x0804b712 in receive () at snmpd.c:1149
#7 0x0804b16d in main (argc=3D14, argv=3D0xbfffa564) at snmpd.c:993


The subagent process's stack trace at that time is given below:


(gdb) where
#0 0x00cb3c88 in ___newselect_nocancel () from /lib/tls/libc.so.6
#1 0x001d1f9c in snmp_synch_response_cb (ss=3D0xa31aad0, =
pdu=3D0xa31c3f0,=20
response=3D0xbfffbebc, pcb=3D0x97ed2c <agentx_synch_input>)
at snmp_client.c:811
#2 0x0097ef11 in agentx_synch_response (ss=3D0xa31aad0, =
pdu=3D0xa31c3f0,=20
response=3D0xbfffbebc) at mibgroup/agentx/client.c:116
#3 0x0097f3ce in agentx_register (ss=3D0xa31aad0, start=3D0xa31c2b8,
startlen=3D1,=20
priority=3D0, range_subid=3D0, range_ubound=3D0, timeout=3D0, =
flags=3D0 '\0',=20
contextName=3D0xa31c350 "slsalpha:7888") at
mibgroup/agentx/client.c:223
#4 0x009720af in agentx_registration_callback (majorID=3D1, =
minorID=3D1,=20
serverarg=3D0xbfffbfa0, clientarg=3D0xa31aad0)
at mibgroup/agentx/subagent.c:575
#5 0x0020ec3f in snmp_call_callbacks (major=3D1, minor=3D1,
caller_arg=3D0xbfffbfa0)
at callback.c:224
#6 0x00968542 in netsnmp_register_mib (moduleName=3D0xa31c2c8 "",
var=3D0x0,=20
varsize=3D0, numvars=3D0, mibloc=3D0xa31c2b8, mibloclen=3D1, =
priority=3D0,=20
range_subid=3D0, range_ubound=3D0, ss=3D0x0, context=3D0xa31c350
"slsalpha:7888",=20
timeout=3D0, flags=3D0, reginfo=3D0xa31c5b8, perform_callback=3D1)
at agent_registry.c:691
#7 0x0096d233 in netsnmp_register_handler (reginfo=3D0xa31c5b8)
at agent_handler.c:255
#8 0x0091e08e in netsnmp_register_null_context (loc=3D0xa31c2b8,
loc_len=3D1,=20
contextName=3D0xa31bca0 "slsalpha:7888") at null.c:38
#9 0x00967e26 in netsnmp_subtree_load (new_sub=3D0xa31bdb8,=20
context_name=3D0xa31bca0 "slsalpha:7888") at agent_registry.c:397
#10 0x00968387 in netsnmp_register_mib (moduleName=3D0xa31bc60
"gdcGpsWeek",=20
var=3D0x0, varsize=3D0, numvars=3D0, mibloc=3D0xa31bcb8, =
mibloclen=3D11,=20
priority=3D127, range_subid=3D0, range_ubound=3D0, ss=3D0x0,=20
context=3D0xa31bca0 "slsalpha:7888", timeout=3D0, flags=3D0,
reginfo=3D0xa31bc28,=20
perform_callback=3D1) at agent_registry.c:629
#11 0x0096d233 in netsnmp_register_handler (reginfo=3D0xa31bc28)
at agent_handler.c:255
#12 0x0091fe75 in netsnmp_register_serialize (reginfo=3D0xa31bc28)
at serialize.c:46
#13 0x0091d061 in netsnmp_register_scalar (reginfo=3D0xa31bc28) at
scalar.c:91

-----Original Message-----
From: Robert Story [mailto:rstory@freesnmp.com]=20
Sent: Tuesday, February 15, 2005 3:44 PM
To: Riju Kallivalappil
Cc: net-snmp-coders@lists.sourceforge.net
Subject: Re: Managing multiple instances of a MIB

On Tue, 15 Feb 2005 10:55:17 -0800 Riju wrote:
RK> On Fri, 11 Feb 2005 16:56:17 -0800 Riju wrote:
RK> RK> Do SNMP v3 contexts work with agentx in 5.2.1?=20
RK>=20
RK> Yes, they should.

But apparently they don't. Sigh.

RK> RK> I've been trying to get this work for the past few days. I was
trying
RK> RK> with 5.2 initially. Didn't work. So, I tried upgrading to 5.2.1.
Still
RK> RK> doesn't work. When I turn on the debug level logs I can see that
the
RK> RK> master agent forwards the request to the correct subagent. But,
the
RK> RK> context information doesn't seem to reach the subagent. And
subagent
RK> RK> returns " No Such Object available on this agent at this OID"
error.
RK> RK>=20
RK> RK> (This setup works fine when I do not use a context or use the
context
RK> RK> "")

I *know* that I tested this, so I'm not sure how it got broken. But it
does
indeed appear to be broken. Try this simple patch and see if it gets you
going:

Index: mibgroup/agentx/master_admin.c
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3 D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3 D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3 D
RCS file:
/cvsroot/net-snmp/net-snmp/agent/mibgroup/agentx/master_admin.c,v
retrieving revision 5.6
diff -u -r5.6 master_admin.c
--- mibgroup/agentx/master_admin.c 9 Nov 2002 15:06:40 -0000
5.6
+++ mibgroup/agentx/master_admin.c 15 Feb 2005 23:41:55 -0000
@@ -229,6 +229,9 @@
=20
reg->handler->myvoid =3D session;
reg->global_cacheid =3D cacheid;
+ if (NULL !=3D pdu->community)
+ reg->contextName =3D pdu->community;
+
/*
* register mib. Note that for failure cases, the registration info
* (reg) will be freed, and thus is no longer a valid pointer.


--=20
Robert Story; NET-SNMP Junkie
Support: <http://www.net-snmp.org/> <irc://irc.freenode.net/#net-snmp>
Archive:
<http://sourceforge.net/mailarchive/forum.php?forum=3Dnet-snmp-coders>

You are lost in a twisty maze of little standards, all different.=20


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