#!/usr/local/bin/perl
use Socket;

my $log = "/var/log/snmp/trap.log";
my $nslookup = 1;
my $debug = 0;

my $port = 162;
my $proto = getprotobyname('udp') || &error("getprotobyname:$!");
my $that = sockaddr_in($port, INADDR_ANY) || &error("sockaddr_in:$!");
socket(S, AF_INET, SOCK_DGRAM, $proto) || &error("socket:$!");
bind(S, $that) || &error("bind:$!");
binmode S;

while(1) {
	my $data = "";
	recv(S, $data, 256, 0) || ($data = "\0"x73 . "recv:$!");
	print "recv\n" . &dump($data) . "\n"  if($debug);

	my ($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst) = localtime(time);
	my $date = sprintf("%04d/%02d/%02d %02d:%02d:%02d",
		$year +1900, $mon +1, $mday, $hour, $min, $sec );

	my $src = sprintf("%d.%d.%d.%d", unpack("C4", substr($data, 0x21, 4)));
	my $msg = substr($data, 0x49);
	chomp($msg);

	if( $nslookup ) {
		if( $msg =~ /^(\@in) (\d+)\.(\d+)\.(\d+)\.(\d+) (.*)$/ ) {
			my $tmp = pack("C4", $2, $3, $4, $5);
			$tmp = gethostbyaddr($tmp, AF_INET);
			$tmp = "$2.$3.$4.$5"  if($tmp eq "");
			$msg = sprintf("%s %s %s", $1, $tmp, $6);
		}
	}

	if( open(F, ">> $log") ) {
		printf(F "%s %s %s\n", $date, $src, $msg);
		close(F);
	}
}

close(S) || &error("close:$!");
exit 0;

sub dump
{
	my @data = unpack( "C*", $_[0] );
	my $line;
	my $i = 0;
	my $msg = '';

	foreach ( @data ) {
		if( ($i % 0x10)==0 ) {
			$msg = $msg . sprintf( "%05X : " , $i );
			$line = '';
		}
		$msg = $msg . "- "  if( ($i % 0x10) && ($i % 0x08)==0 );
		$msg = $msg . sprintf( "%02X ", $_ );
		if( $_ >= 0x20 && $_ <= 0x7E ) {
			$line = sprintf( "%s%c", $line, $_ );
		} else {
			$line = "$line.";
		}
		$i++;
		$msg = $msg . "  $line\n"  if( ($i % 0x10)==0 );
	}

	if( $i % 0x10 ) {
		$msg = $msg . ' 'x ( (16-($i % 0x10)) * 3);
		$msg = $msg . '  '  if( ($i % 0x10) < 9 );
		$msg = $msg . "  $line\n";
	}
	return $msg;
}

sub error
{
	print "error:$_[0]\n";
	exit(1);
}