pysnmp 4.2.3：pysnmp.smi.error.SmiError：importSymbols：空的MIB模块名称

Question

I have two scenarios, both reference SNMP.py in this answer :

pysnmp (v4.2.3) and pysnmp-mibs (v0.1.4) :

>>> # pysnmp-mibs 0.1.4 and pysnmp 4.2.3
>>> from SNMP import v2c
>>> snmp = v2c('172.16.1.1', 'public')
>>> snmp.walk('ifName')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "SNMP.py", line 115, in walk
    (('', oid),),
  File "/usr/local/lib/python2.6/dist-packages/pysnmp-4.2.3-py2.6.egg/pysnmp/entity/rfc3413/oneliner/cmdgen.py", line 449, in nextCmd
  File "/usr/local/lib/python2.6/dist-packages/pysnmp-4.2.3-py2.6.egg/pysnmp/entity/rfc3413/oneliner/cmdgen.py", line 150, in makeReadVarBinds
  File "/usr/local/lib/python2.6/dist-packages/pysnmp-4.2.3-py2.6.egg/pysnmp/entity/rfc3413/oneliner/mibvar.py", line 161, in resolveWithMib
  File "/usr/local/lib/python2.6/dist-packages/pysnmp-4.2.3-py2.6.egg/pysnmp/smi/builder.py", line 295, in importSymbols
pysnmp.smi.error.SmiError: importSymbols: empty MIB module name
>>>

pysnmp (v4.2.2) and pysnmp-mibs (v0.1.3) :

>>> # After removing pysnmp / pysnmp-mibs / pyasn.1 and installing with:
>>> #   easy_install pysnmp==4.2.2 pysnmp-mibs==0.1.3
>>> snmp = v2c('172.16.1.1', 'public')
>>> snmp.walk('ifName')
[SNMPObject(modName='IF-MIB', symName='ifName', index=1, value='Null0'), SNMPObject(modName='IF-MIB', symName='ifName', index=2, value='Internal-Data0/0'), SNMPObject(modName='IF-MIB', symName='ifName', index=3, value='Ethernet0/0'), SNMPObject(modName='IF-MIB', symName='ifName', index=4, value='Ethernet0/1'), SNMPObject(modName='IF-MIB', symName='ifName', index=5, value='Ethernet0/2'), SNMPObject(modName='IF-MIB', symName='ifName', index=11, value='Internal-Data0/1'), SNMPObject(modName='IF-MIB', symName='ifName', index=12, value='_internal_loopback'), SNMPObject(modName='IF-MIB', symName='ifName', index=13, value='Virtual254'), SNMPObject(modName='IF-MIB', symName='ifName', index=14, value='Vlan1'), SNMPObject(modName='IF-MIB', symName='ifName', index=15, value='OUTSIDE'), SNMPObject(modName='IF-MIB', symName='ifName', index=16, value='INSIDE')]
>>>

Question

What is wrong when I use pysnmp v4.2.3? Is the issue in SNMP.py or somewhere in the pysnmp libraries?

Update 1

When I use cmdgen.MibVariable(oid).loadMibs(), as suggested by Ilya, I still get errors...

pysnmp.smi.error.NoSuchObjectError: NoSuchObjectError({'str': "Can't resolve node name ::('ifName',) at <pysnmp.smi.view.MibViewController instance at 0x2af9e60>"})

How can I resolve this error? I am using the following SNMP.py code:

---

from collections import namedtuple as NT
from datetime import datetime
import string
import re

from pysnmp.entity.rfc3413.oneliner import cmdgen
from pysnmp.smi import builder, view, error
from numpy import int64, float64

# NOTE!!!
# It is best to install the pysnmp-mibs package from pypi... this makes
# a lot of symbolic MIB names "just work"


# See this link below for many oneliner examples...
# http://pysnmp.sourceforge.net/examples/4.x/v3arch/oneliner/index.html

class v2c(object):
    """Build an SNMPv2c manager object"""
    def __init__(self, ipaddr=None, device=None, community='Public',
        retries=3, timeout=9):
        self.device = device
        self.ipaddr = ipaddr
        self.community = community
        self.SNMPObject = NT('SNMPObject', ['modName', 'datetime', 'symName',
            'index', 'value'])
        self.SNMPIndexed = NT('SNMPIndexed', ['modName', 'datetime', 'symName',
            'index', 'value'])
        self.query_timeout = float(timeout)/int(retries)
        self.query_retries = int(retries)
        self._index = None

        self.cmdGen = cmdgen.CommandGenerator()

    def index(self, oid=None):
        """Build an SNMP Manager index to reference in get or walk operations.  First v2c.index('ifName').  Then, v2c.get_index('ifHCInOctets', 'eth0') or v2c.walk_index('ifHCInOctets').  Instead of referencing a numerical index, the index will refer to the value that was indexed."""
        self._index = dict()
        self._intfobj = dict()
        snmpidx = self.walk(oid=oid)
        for ii in snmpidx:
            ## the dicts below are keyed by the SNMP index number
            # value below is the text string of the intf name
            self._index[ii.index] = ii.value
            # value below is the intf object
            if not (self.device is None):
                self._intfobj[ii.index] = self.device.find_match_intf(ii.value,
                    enforce_format=False)

    def walk_index(self, oid=None):
        """Example usage, first index with v2c.index('ifName'), then v2c.get_index('ifHCInOctets', 'eth0')"""
        if not (self._index is None):
            tmp = list()
            snmpvals = self.walk(oid=oid)
            for idx, ii in enumerate(snmpvals):
                tmp.append([ii.modName, datetime.now(), ii.symName,
                    self._index[ii.index], ii.value])

            return map(self.SNMPIndexed._make, tmp)
        else:
            raise ValueError, "Must populate with SNMP.v2c.index() first"

    def walk(self, oid=None):
        if isinstance(self._format(oid), tuple):
            errorIndication, errorStatus, errorIndex, \
            varBindTable = self.cmdGen.nextCmd(
                        cmdgen.CommunityData('test-agent', self.community),
                        cmdgen.UdpTransportTarget((self.ipaddr, 161),
                        retries=self.query_retries,
                        timeout=self.query_timeout),
                        self._format(oid),
                    )
            # Parsing only for now... no return value...
            self._parse(errorIndication, errorStatus, errorIndex, varBindTable)
        elif isinstance(oid, str):
            errorIndication, errorStatus, errorIndex, \
                             varBindTable = self.cmdGen.nextCmd(
                # SNMP v2
                cmdgen.CommunityData('test-agent', self.community),
                # Transport
                cmdgen.UdpTransportTarget((self.ipaddr, 161)),
                cmdgen.MibVariable(oid).loadMibs(),
                )
            return self._parse_resolve(errorIndication, errorStatus,
                errorIndex, varBindTable)
        else:
            raise ValueError, "Unknown oid format: %s" % oid

    def get_index(self, oid=None, index=None):
        """In this case, index should be similar to the values you indexed from... i.e. if you index with ifName, get_index('ifHCInOctets', 'eth0')"""
        if not (self._index is None) and isinstance(index, str):
            # Map the interface name provided in index to an ifName index...
            snmpvals = None
            for idx, value in self._index.items():
                if index == value:
                    # if there is an exact match between the text index and the
                    # snmp index value...
                    snmpvals = self.get(oid=oid, index=idx)
                    break
            else:
                # TRY mapping the provided text index into an interface obj
                _intfobj = self.device.find_match_intf(index)
                if not (_intfobj is None):
                    for key, val in self._intfobj.items():
                        if (val==_intfobj):
                            snmpvals = self.get(oid=oid, index=key)
                            break

            # Ensure we only parse a valid response...
            if not (snmpvals is None):
                tmp = [snmpvals.modName, datetime.now(), snmpvals.symName,
                    self._index[snmpvals.index], snmpvals.value]
                return self.SNMPIndexed._make(tmp)

        elif not isinstance(index, str):
            raise ValueError, "index must be a string value"
        else:
            raise ValueError, "Must populate with SNMP.v2c.index() first"

    def get(self, oid=None, index=None):
        if isinstance(self._format(oid), tuple):
            errorIndication, errorStatus, errorIndex, \
            varBindTable = self.cmdGen.getCmd(
                        cmdgen.CommunityData('test-agent', self.community),
                        cmdgen.UdpTransportTarget((self.ipaddr, 161),
                        retries=self.query_retries,
                        timeout=self.query_timeout),
                        self._format(oid),
                    )
            # Parsing only for now... no return value...
            self._parse(errorIndication, errorStatus, errorIndex, varBindTable)
        elif isinstance(oid, str) and isinstance(index, int):
            errorIndication, errorStatus, errorIndex, \
                             varBindTable = self.cmdGen.getCmd(
                # SNMP v2
                cmdgen.CommunityData('test-agent', self.community),
                # Transport
                cmdgen.UdpTransportTarget((self.ipaddr, 161)),
                cmdgen.MibVariable(oid).loadMibs(),
                )
            return self._parse_resolve(errorIndication, errorStatus,
                errorIndex, [varBindTable])[0]
        else:
            raise ValueError, "Unknown oid format: %s" % oid

    def bulkwalk(self, oid=None):
        """SNMP bulkwalk a device.  NOTE: This often is faster, but does not work as well as a simple SNMP walk"""
        if isinstance(self._format(oid), tuple):
            errorIndication, errorStatus, errorIndex, varBindTable = self.cmdGen.bulkCmd(
                        cmdgen.CommunityData('test-agent', self.community),
                        cmdgen.UdpTransportTarget((self.ipaddr, 161),
                        retries=self.query_retries,
                        timeout=self.query_timeout),
                0,
                25,
                self._format(oid),
                )
            return self._parse(errorIndication, errorStatus,
                errorIndex, varBindTable)
        elif isinstance(oid, str):
            errorIndication, errorStatus, errorIndex, varBindTable = self.cmdGen.bulkCmd(
                        cmdgen.CommunityData('test-agent', self.community),
                        cmdgen.UdpTransportTarget((self.ipaddr, 161),
                        retries=self.query_retries,
                        timeout=self.query_timeout),
                0,
                25,
                cmdgen.MibVariable(oid).loadMibs(),
                )
            return self._parse_resolve(errorIndication, errorStatus,
                errorIndex, varBindTable)
        else:
            raise ValueError, "Unknown oid format: %s" % oid

    def _parse_resolve(self, errorIndication=None, errorStatus=None,
        errorIndex=None, varBindTable=None):
        """Parse MIB walks and resolve into MIB names"""
        retval = list()
        if errorIndication:
            print errorIndication
        else:
            if errorStatus:
                print '%s at %s\n' % (
                    errorStatus.prettyPrint(),
                    varBindTable[-1][int(errorIndex)-1]
                    )
            else:
                for varBindTableRow in varBindTable:
                    for oid, val in varBindTableRow:
                        (symName, modName), indices = cmdgen.mibvar.oidToMibName(
                            self.cmdGen.mibViewController, oid
                            )
                        val = cmdgen.mibvar.cloneFromMibValue(
                            self.cmdGen.mibViewController, modName, symName,
                            val)
                        # Try to parse the index as an int first,
                        # then as a string
                        try:
                            index = int(string.join(map(lambda v: v.prettyPrint(), indices), '.'))
                        except ValueError:
                            index = str(string.join(map(lambda v: v.prettyPrint(), indices), '.'))

                        # Re-format values as float or integer, if possible...
                        tmp = val.prettyPrint()
                        if re.search(r"""^\s*\d+\s*$""", tmp):
                            value = int64(tmp)
                        elif re.search(r"""^\s*\d+\.\d+\s*$""", tmp):
                            value = float64(tmp)
                        else:
                            value = tmp

                        retval.append(self.SNMPObject._make([modName,
                            datetime.now(), symName, index, value]))
            return retval

    def _parse(self, errorIndication, errorStatus, errorIndex,
        varBindTable):
        if errorIndication:
           print errorIndication
        else:
            if errorStatus:
                print '%s at %s\n' % (
                    errorStatus.prettyPrint(),
                    errorIndex and varBindTable[-1][int(errorIndex)-1] or '?'
                    )
            else:
                for varBindTableRow in varBindTable:
                    for name, val in varBindTableRow:
                        print '%s = %s' % (name.prettyPrint(), val.prettyPrint())

    def _format(self, oid):
        """Format a numerical OID in the form of 1.3.4.1.2.1 into a tuple"""
        if isinstance(oid, str):
            if re.search('(\d+\.)+\d+', oid):
                tmp = list()
                for ii in oid.split('.'):
                    tmp.append(int(ii))
                return tuple(tmp)
        else:
            return oid

Answer 1

Besides other changes to MIB access interface, pysnmp developers consider an-empty-string-as-a-wildcard-indicator to be too error prone so they replaced it with an explicit call MibVariable.loadModules() .

So in case is pysnmp.version exists and indicates it's 4.2.3 or greater, in SNMP.py you should replace:

...
(('', oid),),
...

with something like:

...
cmdgen.MibVariable(oid).loadMibs(),
...

It's the loadMibs() method which does the magic. See more on MibVariable usage here and other details here .

BTW, MibVariable seems to handle OID detection and conversion all by itself so you might not need to duplicate that logic in SNMP.py