NetSNMP::agent − Perl extension for the net−snmp agent.
use
NetSNMP::agent;
my $agent = new NetSNMP::agent('Name' =>
'my_agent_name');
This module implements an API set to make a SNMP agent act as a snmp agent, a snmp subagent (using the AgentX subagent protocol) and/or embedded perl-APIs directly within the traditional net-snmp agent daemon.
Also see the tutorial about the genaral Net-SNMP C API, which this module implements in a perl-way, and a perl specific tutorial at:
http://www.net−snmp.org/tutorial−5/toolkit/
use
NetSNMP::agent (':all');
use NetSNMP::ASN qw(ASN_OCTET_STR);
my $value = "hello world";
sub myhandler {
my ($handler, $registration_info, $request_info, $requests)
= @_;
my $request;
for($request = $requests; $request; $request =
$request−>next()) {
my $oid = $request−>getOID();
if ($request_info−>getMode() == MODE_GET) {
# ... generally, you would calculate value from oid
if ($oid == new
NetSNMP::OID(".1.3.6.1.4.1.8072.9999.9999.7375.1.0"))
{
$request−>setValue(ASN_OCTET_STR, $value);
}
} elsif ($request_info−>getMode() == MODE_GETNEXT)
{
# ... generally, you would calculate value from oid
if ($oid < new
NetSNMP::OID(".1.3.6.1.4.1.8072.9999.9999.7375.1.0"))
{
$request−>setOID(".1.3.6.1.4.1.8072.9999.9999.7375.1.0");
$request−>setValue(ASN_OCTET_STR, $value);
}
} elsif ($request_info−>getMode() ==
MODE_SET_RESERVE1) {
if ($oid != new
NetSNMP::OID(".1.3.6.1.4.1.8072.9999.9999.7375.1.0"))
{ # do error checking here
$request−>setError($request_info,
SNMP_ERR_NOSUCHNAME);
}
} elsif ($request_info−>getMode() ==
MODE_SET_ACTION) {
# ... (or use the value)
$value = $request−>getValue();
}
}
}
my $agent = new NetSNMP::agent(
# makes the agent read a my_agent_name.conf file
'Name' => "my_agent_name",
'AgentX' => 1
);
$agent−>register("my_agent_name",
".1.3.6.1.4.1.8072.9999.9999.7375",
\&myhandler);
my $running = 1;
while($running) {
$agent−>agent_check_and_process(1);
}
$agent−>shutdown();
# place this in
a .pl file, and then in your snmpd.conf file put:
# perl do '/path/to/file.pl';
use NetSNMP::agent;
my $agent;
sub myhandler {
my ($handler, $registration_info, $request_info, $requests)
= @_;
# ...
}
$agent = new NetSNMP::agent(
'Name' => 'my_agent_name'
);
$agent−>register("my_agent_name",
".1.3.6.1.4.1.8072.9999.9999.7375",
\&myhandler);
$agent−>main_loop();
new ( OPTIONS )
This is the constructor for a new NetSNMP::agent object.
Possible options are:
Name − Name of the agent (optional, defaults to
"perl")
(The snmp library will read a NAME.conf snmp
configuration file based on this argument.)
AgentX − Make us a sub−agent (0 = false, 1 =
true)
(The Net−SNMP master agent must be running first)
Ports − Ports this agent will listen on (EG:
"udp:161,tcp:161")
Example:
$agent = new NetSNMP::agent(
'Name' => 'my_agent_name',
'AgentX' => 1
);
register (NAME,
OID, \&handler_routine )
Registers the callback handler with given OID.
$agent−>register();
A return code of 0 indicates no error.
agent_check_and_process ( BLOCKING )
Run one iteration of the main loop.
BLOCKING − Blocking or non−blocking call. 1 =
true, 0 = false.
$agent−>agent_check_and_process(1);
main_loop ()
Runs the agent in a loop. Does not return.
shutdown ()
Nicely shuts down the agent or sub−agent.
$agent−>shutdown();
handler (
HANDLER, REGISTRATION_INFO, REQUEST_INFO, REQUESTS )
The handler is called with the following parameters:
HANDLER − FIXME
REGISTRATION_INFO − what are the correct meanings of
these?
REQUEST_INFO −
REQUESTS −
Example handler:
sub myhandler {
my ($handler, $reg_info, $request_info, $requests) = @_;
# ...
}
The handler subroutine will be called when a SNMP request received by the agent for anything below the registered OID. The handler is passed 4 arguments: $handler, $registration_info, $request_info, $requests. These match the arguments passed to the C version of the same API. Note that they are not entirely complete objects but are functional "enough" at this point in time.
getMode ()
Returns the mode of the request. See the MODES section for
list of valid modes.
$mode = $request−>getMode();
getRootOID ()
Returns a NetSNMP::OID object that describes the
registration
point that the handler is getting called for (in case you
register one handler function with multiple OIDs, which
should
be rare anyway)
$root_oid = $request−>getRootOID();
next ()
Returns the next request in the list or undef if there is no
next request.
$request = $request−>next();
getOID ()
Returns the oid of the request (a NetSNMP::OID class).
$oid = $request−>getOID();
setOID (new NetSNMP::OID("someoid"))
Sets the OID of the request to a passed oid value. This
should generally only be done during handling of GETNEXT
requests.
$request−>setOID(new
NetSNMP::OID("someoid"));
getValue ()
Returns the value of the request. Used for example when
setting values.
$value = $request−>getValue();
FIXME: how to get the type of the value? Is it even
available?
[Wes: no, not yet.]
setValue ( TYPE, DATA )
Sets the data to be returned to the daemon.
Returns 1 on success, 0 on error.
TYPE − Type of the data. See NetSNMP::ASN for valid
types.
DATA − The data to return.
$ret = $request−>setValue(ASN_OCTET_STR,
"test");
setError ( REQUEST_INFO, ERROR_CODE )
Sets the given error code for the request. See the ERROR
CODES
section for list of valid codes.
$request−>setError($request_info,
SNMP_ERR_NOTWRITABLE);
getProcessed ()
The processed flag indicates that a request does not need to
be dealt with because someone else (a higher handler) has
dealt with it already.
$processed = $request−>getProcessed();
setProcessed ( PROCESSED )
Sets the processed flag flag in the request. You generally
should not have to set this yourself.
PROCESSED − 0 = false, 1 = true
$request−>setProcessed(1);
getDelegated ()
If you can handle a request in the background or at a future
time (EG, you're waiting on a file handle, or network
traffic,
or ...), the delegated flag can be set in the request. When
the request is processed in the future the flag should be
set
back to 0 so the agent will know that it can wrap up the
original request and send it back to the manager. This has
not been tested within perl, but it hopefully should work.
$delegated = $request−>getDelegated();
setDelegated ( DELEGATED )
Sets the delegated flag.
DELEGATED − 0 = false, 1 = true
$request−>setDelegated(1);
getRepeat ()
The repeat flag indicates that a getbulk operation is being
handled and this indicates how many answers need to be
returned. Generally, if you didn't register to directly
handle getbulk support yourself, you won't need to deal with
this value.
$repeat = $request−>getRepeat();
setRepeat ( REPEAT )
Sets the repeat count (decrement after answering requests if
you handle getbulk requests yourself)
REPEAT − repeat count FIXME
$request−>setRepeat(5);
getSourceIp ()
Gets the IPv4 address of the device making the request to
the handler.
use Socket;
print "Source: ",
inet_ntoa($request−>getSourceIp()), "\n";
getDestIp ()
Gets the IPv4 address of the destination that the request
was sent to.
use Socket;
print "Destination: ",
inet_ntoa($request−>getDestIp()),
"\n";
MODE_GET
MODE_GETBULK
MODE_GETNEXT
MODE_SET_ACTION
MODE_SET_BEGIN
MODE_SET_COMMIT
MODE_SET_FREE
MODE_SET_RESERVE1
MODE_SET_RESERVE2
MODE_SET_UNDO
SNMP_ERR_NOERROR
SNMP_ERR_TOOBIG
SNMP_ERR_NOSUCHNAME
SNMP_ERR_BADVALUE
SNMP_ERR_READONLY
SNMP_ERR_GENERR
SNMP_ERR_NOACCESS
SNMP_ERR_WRONGTYPE
SNMP_ERR_WRONGLENGTH
SNMP_ERR_WRONGENCODING
SNMP_ERR_WRONGVALUE
SNMP_ERR_NOCREATION
SNMP_ERR_INCONSISTENTVALUE
SNMP_ERR_RESOURCEUNAVAILABLE
SNMP_ERR_COMMITFAILED
SNMP_ERR_UNDOFAILED
SNMP_ERR_AUTHORIZATIONERROR
SNMP_ERR_NOTWRITABLE
Please mail the net−snmp−[email protected] mailing list for help, questions or comments about this module.
Module written
by:
Wes Hardaker <[email protected]>
Documentation
written by:
Toni Willberg <[email protected]>
Wes Hardaker <[email protected]>
NetSNMP::OID(3), NetSNMP::ASN(3), perl(1).