#!/usr/bin/perl -w
### discover
### Author:	  Simon Leinen <simon@switch.ch>
### Date Created: 1998-Oct-16
###
### discover ADDRESS [COMMUNITY]
###
### Send a specific SNMP request to a IP address and wait for replies.
### Can be used with a broadcast or multicast address to discover SNMP
### agents ("Command Responder Applications") responding to a given
### community.  Warning: This code uses internal subroutines of the
### SNMP_Session.pm module which are subject to change :-(
###
use strict;
use vars qw($MULTILINE_MATCHING);

require 5;

use SNMP_Session "0.61";
use BER;
use Socket;

my $host = shift @ARGV || die;
my $community = shift @ARGV || 'public';

my $sysDescr = encode_oid (1,3,6,1,2,1,1,1,0);

my $session = SNMP_Session->open ($host, $community, 161)
    || die "Cannot open SNMP session";
my @oids = ($sysDescr);
$session->send_query ($session->encode_get_request (@oids));
while ($session->wait_for_response ($session->timeout)) {
    my($response_length);

    $response_length
	= $session->receive_response_3 (SNMP_Session::get_response, \@oids, 0);
    if ($response_length) {
	my $response = $session->pdu_buffer;
	my ($binding, $bindings, $oid, $value);
	eval {
	    ($bindings) = $session->decode_get_response ($response);
	};
	while ($bindings ne '') {
	    ($binding,$bindings) = decode_sequence ($bindings);
	    ($oid,$value) = decode_by_template ($binding, "%O%@");
	    ##print $pretty_oids{$oid}," => ",
	    {
		my $string = pretty_print ($value);
		my $sender = $session->{'last_sender_addr'};
		local $MULTILINE_MATCHING = 1;
		$string =~ s/\n/\\n/g;
		$string =~ s/\r/\\r/g;
		print STDOUT pretty_address ($sender), "\n  ";
		print STDOUT $string, "\n";
	    }
	}
    }
}

$session->close ();
1;

sub pretty_address
{
    my($addr) = shift;
    my($port,$ipaddr) = unpack_sockaddr_in($addr);
    my $hostname = gethostbyaddr ($ipaddr, AF_INET);
    return $hostname ? $hostname : ('['.inet_ntoa($ipaddr).']');
}