[pysnmp-users] pysnmp / pyasn1 decode problem with multi-line traps

[Tom Kr. <to...@we...>]

Hi there,
 
I'm new to this mailing list and I have a issue with the pysnmp / pyasn1 module.
I use python with version 3.4 and pysnmp with version 4.2.5.
The OS is Ubuntu server 14.04.2.
 
# lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 14.04.2 LTS
Release:        14.04
Codename:       trusty
 
ii  python-pysnmp4                        4.2.5-1                               all          Python SNMP library for agents and managers (Python 2 module)
ii  python-pyasn1                         0.1.7-1ubuntu2                        all          ASN.1 library for Python (Python 2 module)
ii  python3.4                             3.4.0-2ubuntu1                        amd64        Interactive high-level object-oriented language (version 3.4)
 
I try to use the following script to read snmp traps and print this traps on the screen.
But unfortunately I have some troubles with multi-line traps.
This traps are only shown as hex values. 
I think the problem is the decoder but I'm not very familiar with python and also not with pysnmp.
 
I hope someone of you can help me or give me some ideas what I should do next.
For the moment I have no idea. 
 
The script:
----------------------------------------------------------------------------------------------
import sys,os
 
sys.path.append('/usr/share/pyshared/')
 
from pysnmp.carrier.asynsock.dispatch import AsynsockDispatcher
from pysnmp.carrier.asynsock.dgram import udp, udp6
from pyasn1.codec.ber import decoder
from pysnmp.proto import api
 
def trapCallback(transportDispatcher, transportDomain, transportAddress, wholeMsg):
    while wholeMsg:
        msgVer = int(api.decodeMessageVersion(wholeMsg))
        if msgVer in api.protoModules:
            pMod = api.protoModules[msgVer]
        else:
            print('Unsupported SNMP version %s' % msgVer)
            return
        reqMsg, wholeMsg = decoder.decode(
            wholeMsg, asn1Spec=pMod.Message(),
            )
        print('Notification message from %s:%s: ' % (
            transportDomain, transportAddress
            )
        )
        reqPDU = pMod.apiMessage.getPDU(reqMsg)
        if reqPDU.isSameTypeWith(pMod.TrapPDU()):
            if msgVer == api.protoVersion1:
                print('Enterprise: %s' % (
                    pMod.apiTrapPDU.getEnterprise(reqPDU).prettyPrint()
                    )
                )
                print('Agent Address: %s' % (
                    pMod.apiTrapPDU.getAgentAddr(reqPDU).prettyPrint()
                    )
                )
                print('Generic Trap: %s' % (
                    pMod.apiTrapPDU.getGenericTrap(reqPDU).prettyPrint()
                    )
                )
                print('Specific Trap: %s' % (
                    pMod.apiTrapPDU.getSpecificTrap(reqPDU).prettyPrint()
                    )
                )
                print('Uptime: %s' % (
                    pMod.apiTrapPDU.getTimeStamp(reqPDU).prettyPrint()
                    )
                )
                varBinds = pMod.apiTrapPDU.getVarBindList(reqPDU)
            else:
                varBinds = pMod.apiPDU.getVarBindList(reqPDU)
            print('Var-binds:')
            for oid, val in varBinds:
                print('%s = %s' % (oid.prettyPrint(), val.prettyPrint()))
    return wholeMsg
 
transportDispatcher = AsynsockDispatcher()
 
transportDispatcher.registerRecvCbFun(trapCallback)
 
# UDP/IPv4
transportDispatcher.registerTransport(
    udp.domainName, udp.UdpSocketTransport().openServerMode(('localhost', 162))
)
 
# UDP/IPv6
transportDispatcher.registerTransport(
    udp6.domainName, udp6.Udp6SocketTransport().openServerMode(('::1', 162))
)
 
transportDispatcher.jobStarted(1)
 
try:
    # Dispatcher will never finish as job#1 never reaches zero
    transportDispatcher.runDispatcher()
except:
    transportDispatcher.closeDispatcher()
   raise
----------------------------------------------------------------------------------------------
 
 
As you can see, the script is an example from the project side.
(http://pysnmp.sourceforge.net/examples/current/v1arch/manager/ntfrcv/v2c-multiple-transports.html)
 
This is the part of the trap where the hex value is shown instead of the plain text.
string=0x4f70657261746f722058585858585858585858203a20585858585858585858582c2058585858585858202c204c6f63616c6c792061757468656e74696361746564202d207375636365737366756c6c79207369676e6564206f6e20746f20746865207465726d696e616c20275858582e5858582e582e584058272061742031343a3238207573696e672027585858585858585820585858205858585858585858272e0a4f70657261746f722050726f66696c65733a2058585858585858585858585858
 
This is the message I would  expect.
"Operator XXXXXXXXXX : XXXXXXXXXX, XXXXXXX , Locally authenticated - successfully signed on to the terminal 'XXX.XXX.X.X@X' at 14:28using 'XXXXXXXX XXX XXXXXXXX'.
Operator Profiles: XXXXXXXXXXXXX"
 
For me, the problem is located at the line feed. Is there a possibility to replace any line feed character with a space or nothing?
I think this should be done in the pyasn1 module, but I don't know how.
 
Hope somebody can help me with my problem.
 
Kind regards,
Tom