Trying to get value of an object of type "Object Identifier" with null value the results is "No SNMP response received before timeout".

[leo-aguilar]

Expected behavior

I expected the same result that other applications as MibBrowser and snmpget returns.

Example using snmpget:
$ snmpget -v1 -On -c public 192.168.0.181 1.3.6.1.2.1.2.2.1.22.1
.1.3.6.1.2.1.2.2.1.22.1 = OID: .0

Actual behavior

Trying to get value of an object of type Object Identifier with null value results in No SNMP response received before timeout.

Detailed steps

Trying to get value of an object of type Object Identifier with null value as example:
OID: 1.3.6.1.2.1.2.2.1.22.1 --- that is ifSpecific.1 defined in RFC1213-MIB

The steps:

1. Execute the included script base on v1-get.py example from Quick Start - PySNMP 7.1 Documentation (https://www.pysnmp.com/pysnmp/). The script tries to get value of object 1.3.6.1.2.1.2.2.1.22.1 that is ifSpecific.1 defined in RFC1213-MIB, the agent returns value in compact format (06h 00h), this means the type (06h) and null value (00h) -- no length included.
2. Script returns: No SNMP response received before timeout

Python package information

pyasn1 0.6.1
pysmi 1.5.9
pysnmp 7.1.15

Operating system information

Linux Ubuntu 22.04

Python information

Python 3.10.12

(Optional) Contents of your test script

# based v1-get.py

"""
SNMPv1
++++++

Send SNMP GET request using the following options:

  * with SNMPv1, community 'public'
  * over IPv4/UDP
  * to an Agent at demo.snmplabs.com:161
  * for an instance of SNMPv2-MIB::sysDescr.0 MIB object
  * Based on asyncio I/O framework

Functionally similar to:

| $ snmpget -v1 -c public demo.pysnmp.com SNMPv2-MIB::sysDescr.0

"""  #
import asyncio
from pysnmp.hlapi.v3arch.asyncio import *

async def run():
    snmpEngine = SnmpEngine()

    iterator = get_cmd(
        snmpEngine,
        CommunityData("public", mpModel=0),
        await UdpTransportTarget.create(("192.168.0.181", 161)),
        ContextData(),
        ObjectType(ObjectIdentity("1.3.6.1.2.1.2.2.1.22.1")), # RFC1213-MIB, ifSpecific.1
    )

    errorIndication, errorStatus, errorIndex, varBinds = await iterator

    if errorIndication:
        print(errorIndication)

    elif errorStatus:
        print(
            "{} at {}".format(
                errorStatus.prettyPrint(),
                errorIndex and varBinds[int(errorIndex) - 1][0] or "?",
            )
        )
    else:
        for varBind in varBinds:
            print(" = ".join([x.prettyPrint() for x in varBind]))
    snmpEngine.close_dispatcher()

asyncio.run(run())

Relevant log output

-- see attached files:
fail-debug-capture.txt

No response

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