SNMP trap (coldStart) 送信スクリプト

以前作成した以下の perl スクリプトをエンハンスした。
akrad.hatenablog.com

具体的には、SNMPv1 のcoldStartトラップも SNMPv2cのcoldStartトラップも送信できるようにし、トラップ送信先やSNMPv1トラップの agent-addrフィールドも指定できるようにした。
使い方の例は以下。

1.1.1.1 に、SNMPv2cのcoldStartトラップを送信する。

perl sendTrap.pl -v 2 -d 1.1.1.1

1.1.1.1 に、agent-addrフィールドを 2.2.2.2 として、SNMPv1のcoldStartトラップを送信する。

perl sendTrap.pl -v 1 -d 1.1.1.1 -a 2.2.2.2

作成したperlスクリプトは以下の通り。
sendTrap.pl

use strict;
use warnings;
use Socket;
use Getopt::Long 'GetOptions';

#---------------
# Constant value
#---------------
my $V1_TRAP   = 'a4';
my $V2c_TRAP  = 'a7';
my $SNMP_V1   = 0;
my $SNMP_V2C  = 1;

my $INTEGER      = '02';
my $OCTET_STRING = '04';
my $OBJECT_ID    = '06';
my $SEQUENCE     = '30';
my $IP_ADDRESS   = '40';
my $TIME_TICKS   = '43';

#-------------------
# Set default value
#-------------------
my $destAddr      = 'localhost';
my $destPort      = 162;
my $snmpVersion   = '2';
my $enterpriseOid = '1.2.3.4.5';
my $agentAddr     = '127.0.0.1';

GetOptions(
    'dest=s'      => \$destAddr,
    'version=s'   => \$snmpVersion,
    'agentaddr=s' => \$agentAddr
);

#-------------------
# Check user's input
#-------------------
if ($destAddr =~ /^\d/) { # This is an ip address. Because hostname doesn't start from a digit.
    if (!isIpAddress($agentAddr)) {
        die("$destAddr is not an ip address.");
    }
}

if (($snmpVersion ne '1') and ($snmpVersion ne '2') and ($snmpVersion ne '2c')) {
    die("$snmpVersion must be 1 or 2(2c)");
}

if (!isIpAddress($agentAddr)) {
    die("$agentAddr is not an ip address.");
}


#---------------
# MAIN
#---------------
my $socket;
socket($socket, PF_INET, SOCK_DGRAM, 0) or die "Failed to create socket. $!";

my $addrBin = inet_aton($destAddr);
my $sockAddr = pack_sockaddr_in($destPort, $addrBin);

my $trapData;
if ($snmpVersion eq '1') {
    $trapData = constractV1TrapData();
}
elsif (($snmpVersion eq '2') or ($snmpVersion eq '2c')) {
    $trapData = constractV2cTrapData();
}
else {
    die("Need to specify 1 or 2(2c) for version.");
}

my $trapDataBin = pack("H*", $trapData);
send($socket, $trapDataBin, 0, $sockAddr) or die "Failed to send. $!";


#---------------
# Sub functions
#---------------
sub constractV1TrapData {
    my $snmpVersion  = $SNMP_V1;
    my $commName     = 'public';
    my $pduType      = $V1_TRAP;
    my $requestID    = 10;
    my $errorStatus  = 0;
    my $errorIndex   = 0;
    my $genericTrap  = 0;
    my $specificTrap = 0;
    my $timeStamp    = 0;

    my $snmpVersionBerUnit   = constractBerData($INTEGER, convertDecNumToHexStr($snmpVersion));
    my $commNameBerUnit      = constractBerData($OCTET_STRING, unpack("H*", $commName));
    my $enterpriseOidBerUnit = constractBerData($OBJECT_ID, convertOidStrToHexStr($enterpriseOid));
    my $agentAddrBerUnit     = constractBerData($IP_ADDRESS, convertIpAddrStrToHexStr($agentAddr));
    my $genericTrapBerUnit   = constractBerData($INTEGER, convertDecNumToHexStr($genericTrap));
    my $specificTrapBerUnit  = constractBerData($INTEGER, convertDecNumToHexStr($specificTrap));
    my $timeStampBerUnit     = constractBerData($TIME_TICKS, convertDecNumToHexStr($timeStamp));
    my $emptyVarbindBerUnit  = constractBerData($SEQUENCE, "");
    
    my $trapPduLength = getBinLengthFromHexStr(
                            $enterpriseOidBerUnit,
                            $agentAddrBerUnit,
                            $genericTrapBerUnit,
                            $specificTrapBerUnit,
                            $timeStampBerUnit,
                            $emptyVarbindBerUnit);
    
    my $totalength = getBinLengthFromHexStr(
                        $snmpVersionBerUnit, 
                        $commNameBerUnit, 
                        $pduType,
                        convertDecNumToHexStr($trapPduLength))
                     + $trapPduLength;

    my $trapData = $SEQUENCE . 
                   convertDecNumToHexStr($totalength) .
                   $snmpVersionBerUnit . 
                   $commNameBerUnit . 
                   $pduType .
                   convertDecNumToHexStr($trapPduLength) .
                   $enterpriseOidBerUnit .
                   $agentAddrBerUnit .
                   $genericTrapBerUnit .
                   $specificTrapBerUnit .
                   $timeStampBerUnit .
                   $emptyVarbindBerUnit;
    return $trapData;
}

sub constractV2cTrapData {
    my $snmpVersion = $SNMP_V2C;
    my $commName    = 'public';
    my $pduType     = $V2c_TRAP;
    my $requestID   = 10;
    my $errorStatus = 0;
    my $errorIndex  = 0;

    my $snmpVersionBerUnit = constractBerData($INTEGER, convertDecNumToHexStr($snmpVersion));
    my $commNameBerUnit    = constractBerData($OCTET_STRING, unpack("H*", $commName));
    my $requestIDBerUnit   = constractBerData($INTEGER, convertDecNumToHexStr($requestID));
    my $errorStatusBerUnit = constractBerData($INTEGER, convertDecNumToHexStr($errorStatus));
    my $errorIndexBerUnit  = constractBerData($INTEGER, convertDecNumToHexStr($errorIndex));
    my $varbindData        = constractVarbindData();
    
    my $trapPduLength = getBinLengthFromHexStr(
                            $requestIDBerUnit,
                            $errorStatusBerUnit,
                            $errorIndexBerUnit,
                            $SEQUENCE,
                            convertDecNumToHexStr(getBinLengthFromHexStr($varbindData)),
                            $varbindData);
    
    my $totalength = getBinLengthFromHexStr(
                        $snmpVersionBerUnit, 
                        $commNameBerUnit, 
                        $pduType,
                        convertDecNumToHexStr($trapPduLength))
                     + $trapPduLength;

    my $trapData = $SEQUENCE . 
                   convertDecNumToHexStr($totalength) .
                   $snmpVersionBerUnit . 
                   $commNameBerUnit . 
                   $pduType .
                   convertDecNumToHexStr($trapPduLength) .
                   $requestIDBerUnit .
                   $errorStatusBerUnit .
                   $errorIndexBerUnit .
                   $SEQUENCE .
                   convertDecNumToHexStr(getBinLengthFromHexStr($varbindData)) .
                   $varbindData;
    return $trapData;
}

sub constractVarbindData {
    # ------------------------
    # sysUpTime
    # ------------------------
    my $sysUpTimeOid = '1.3.6.1.2.1.1.3.0';
    my $sysUpTimeOidBerData = constractBerData($OBJECT_ID, convertOidStrToHexStr($sysUpTimeOid));
    my $sysUpTime = 10;
    my $sysUpTimeBerData = constractBerData($TIME_TICKS, convertDecNumToHexStr($sysUpTime));
    my $sysUpTimeVarbindLength = getBinLengthFromHexStr($sysUpTimeOidBerData, $sysUpTimeBerData);
    my $sysUpTimeVarbind = $SEQUENCE . 
                           convertDecNumToHexStr($sysUpTimeVarbindLength) . 
                           $sysUpTimeOidBerData .
                           $sysUpTimeBerData;

    # ------------------------
    # sysTrapOID
    # ------------------------
    my $sysTrapOid = '1.3.6.1.6.3.1.1.4.1.0';
    my $sysTrapOidBerData = constractBerData($OBJECT_ID, convertOidStrToHexStr($sysTrapOid));
    my $sysTrapOidData = '1.3.6.1.6.3.1.1.5.1';
    my $sysTrapBerData = constractBerData($OBJECT_ID, convertOidStrToHexStr($sysTrapOidData));
    my $sysTrapVarbindLength = getBinLengthFromHexStr($sysTrapOidBerData, $sysTrapBerData);
    my $sysTrapVarbind = $SEQUENCE . 
                         convertDecNumToHexStr($sysTrapVarbindLength) . 
                         $sysTrapOidBerData .
                         $sysTrapBerData;
    
    return $sysUpTimeVarbind . $sysTrapVarbind;
}

sub isIpAddress {
    my $ipAddr = shift;
    my @octets = split(/\./, $ipAddr);
    return 0 if (@octets != 4);
    foreach my $octet (@octets) {
        if (!($octet =~ /^\d+$/) or !(0 <= $octet and $octet <= 255)) {
            return 0;
        }
    }
    return 1;
}

sub convertIpAddrStrToHexStr {
    my $ipAddrStr = shift;
    my @octets = split(/\./, $ipAddrStr);
    my $ipAddrHexStr;
    foreach my $octet (@octets) {
        $ipAddrHexStr .= convertDecNumToHexStr($octet);
    }
    return $ipAddrHexStr;
}

sub convertOidStrToHexStr {
    my $oidStr = shift;
    my @oids = split(/\./, $oidStr);
    my $hexStr = convertDecNumToHexStr(40*$oids[0] + $oids[1]);
    for (my $i = 2; $i <= $#oids; $i++) {
        if ($oids[$i] < 128) {
            $hexStr .= convertDecNumToHexStr($oids[$i]);
        }
        else {
            $hexStr .= convertOidNumToHexStrForMultiBytes($oids[$i]);
        }
    }
    return $hexStr;
}

sub convertOidNumToHexStrForMultiBytes {
    my $oidNum = shift;
    my $hexStr = "";
    my $counter = 0;

    my $workVal = $oidNum;
    while (1) {
        my $quotient  = int($workVal / 128);
        my $remainder = $workVal % 128;

        if ($counter != 0) {
            $remainder += 128;
        }
        $hexStr = convertDecNumToHexStr($remainder) . $hexStr;

        if ($quotient == 0) {
            last;
        }
        $workVal = $quotient;
        $counter++;
    }
    return $hexStr;
}

sub getBinLengthFromHexStr {
    my @hexStrs = @_;
    my $binLength = 0;
    foreach my $hexStr (@hexStrs) {
       $binLength += length($hexStr)/2;
    }
    return $binLength;
}

sub constractBerData {
    my ($tag, $data) = @_;
    $data =~ s/\s//g;
    my $binLength = (length($data))/2;
    my $berData = $tag . convertDecNumToHexStr($binLength) . $data;
    return $berData;
}

sub convertDecNumToHexStr {
    my $decNum = shift;
    my $hexStr = sprintf("%02x", $decNum);
    if (length($hexStr)%2 != 0) {
        $hexStr = '0' . $hexStr;
    }
    return $hexStr;
}

上記のスクリプト作成に当たっては、OID を BER(Basic Encoding Rules) 形式でエンコーディングするのがちょっと面倒だった。(convertOidStrToHexStr関数やconvertOidNumToHexStrForMultiBytes関数の辺り・・)
この辺の話については、別途、記事を書きたいと思っている。