Fulko Hew wrote:
On Tue, May 12, 2009 at 9:03 AM, parveen yadav
<[email protected] <mailto:[email protected]>> wrote:
Fulko Hew wrote:
On Tue, May 12, 2009 at 2:23 AM, parveen yadav
<[email protected] <mailto:[email protected]>>
wrote:
Fulko Hew wrote:
On Sat, May 9, 2009 at 5:18 AM, parveen yadav
<[email protected]
<mailto:[email protected]>> wrote:
Wes Hardaker wrote:
On Tue, 05 May 2009 14:27:53 +0530, parveen yadav
<[email protected]> <mailto:[email protected]> said:
py> I am trying to extract agent IP address for which get/set request is
py> generated by snmpget in get_first_data_point,get_next_data_point and
py> table handler. I am table iterator for my table.
No, you can't. Though technically possible some of the time it's
generally not something that you should be doing. SNMP wasn't
designed
to work that way, and although it's possible it breaks under some
conditions. EG, if you ever want to run your code as an AgentX
subagent
that information isn't available at all.
But i think we can extract request ip in case net-snmp
is working as main agent and we do not need to handle
AgentX. But it is hard to find the storage location. I
have tried request structure.
Do i need to look some where else also??
If I understand correctly, then this was something I needed
and I recently
added to the Perl interface for agents, its available in the
upcoming
release, but only for IPv4 based requests, and I don't think
it'll work
for AgentX based agents either.
thanks for reply
I have traced packet from snmp_read. But there is still
confusion about Ipaddress of request. Can somebody clear the
doubt.
Can you be more specific? What are you confused about?
What language are you using?
If you are using Perl, your agent code would look something like
this:
if (!$agent) {
print "The mandatory Perl agent is not defined in this
Net-SNMP installation\n";
return;
}
$agent->register('myprog', '1.2.3.4', \&my_snmp_handler);
sub my_snmp_handler {
my ($handler, $registration_info, $request_info, $requests) = @_;
my $targetIp = inet_ntoa($request_info->getTargetIp());
for (my $request = $requests; $request; $request =
$request->next()) {
handle_oid($targetIp, $request_info, $request);
}
}
I am using C language agent. There is netsnmp_request_info
structure in agent. In table handler , through requests list
handler finds the request to process.
But there is no method like getTargetIp(). It must be perl
specific and there must be some alternate.
I will try to explore this . This must be looking in request info
for Ip.
Correct. getTargetIp() is a function I added to the Perl binding to
NetSnmp.
Below is the C code (for that Perl binding)
I've highlighted the two relevant lines of code.
When I investigated the Net-SNMP C code, I found that the requestor's IP
address was in the reqinfo->asp->pdu->transport_data in the standard inet
structure form. Unfortunately this address in the trasnsport_data
structure
is the 'raw' address in whatever protocol it may have arrived in (IPv4
IPv6, IPX etc.)
and the actual protocol type was lost (thrown away) at a higher level in
the calling stack. So all I could do for my Perl/C stuff was assume I
was receiving the request from an IPv4 address and look at it as such.
To do it correctly would require a change to Net-SNMP so that the address
is correctly decoded and passed down in the reqinfo structure (where there
is already a place where it could reside). I was looking for a quick
and simple change that would meet my needs.
If you want to see my full analysis, I documented it in my change request
to Net-SNMP for my Perl patch. Refer to this for that information:
https://sourceforge.net/tracker/?func=detail&aid=2709705&group_id=12694&atid=312694
<https://sourceforge.net/tracker/?func=detail&aid=2709705&group_id=12694&atid=312694>
I hope this helps you!
Fulko
SV *
narqi_getTargetIp(me)
SV *me;
PREINIT:
netsnmp_agent_request_info *reqinfo;
struct netsnmp_udp_addr_pair_s *addr_pair;
struct in_addr *to;
SV *rarg;
CODE:
reqinfo = (netsnmp_agent_request_info *) SvIV(SvRV(me));
addr_pair = (struct netsnmp_udp_addr_pair_s *)
(reqinfo->asp->pdu->transport_data); <-----
to = (struct in_addr *)
&(addr_pair->local_addr); <-----
rarg = newSVpv((unsigned char *)(&to->s_addr),
sizeof(to->s_addr));
RETVAL = rarg;
OUTPUT:
RETVAL
thanks
Using transport _data, I am able to extract source and destination IP in
table handler. I tried to pass request info to to first and next data
point using raw pointer myvoid in iinfo(iterator info). After dong that
i am able to extract required info in these function also. I will test
few more cases before updating net-snmp code.
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