Fix incorrect datatype (#7)

* Update snmp.py

Fix incorrect datatype- decode is no more required.

* changes as per code review

* add more optimization

* show that wrong type is still used

* fix tests alongwith adding optimization and black formatting

* fix unidiomatic-typecheck and add isort

* clean imports

---------

Co-authored-by: A200146603 <[email protected]>
Co-authored-by: Christian Sahlmann <[email protected]>

.pre-commit-config.yaml

@@ -7,3 +7,8 @@ repos:
     rev: v0.8.0
     hooks:
       - id: yamlfmt
+  - repo: https://github.com/pycqa/isort
+    rev: 5.11.2
+    hooks:
+      - id: isort
+        name: isort (python)

mb_netmgmt/snmp.py

@@ -139,10 +139,10 @@ def to_varbind(oid, response):
     value = response["val"]
     try:
         value = b64decode(value, validate=True)
-        asn1_class = ASN1_Class_UNIVERSAL.__dict__[response["tag"]]
-        value = asn1_class.asn1_object(value)
     except (binascii.Error, TypeError):
         pass
+    asn1_class = ASN1_Class_UNIVERSAL.__dict__[response["tag"]]
+    value = asn1_class.asn1_object(value)
     del response["val"]
     del response["tag"]
     return SNMPvarbind(oid=oid, value=value, **response)

mb_netmgmt/telnet.py

@@ -93,7 +93,7 @@ def handle_username(self):
             password_prompt = result[1].string.encode()
             self.wfile.write(password_prompt)
         except AttributeError:
-            self.handle_request({"command": self.username.decode()}, None)        
+            self.handle_request({"command": self.username.decode()}, None)
 
 
 def extract_username(byte_string):

test/test_mb_netmgmt.py

@@ -1,6 +1,7 @@
 import io
 import os
 import re
+from base64 import b64encode
 from threading import Thread
 from urllib.parse import urlparse
 
@@ -9,6 +10,7 @@
 import pytest
 from ncclient.devices.default import DefaultDeviceHandler
 from ncclient.transport.session import BASE_NS_1_0, MSG_DELIM, to_ele
+from scapy.asn1.asn1 import ASN1_OID
 from scapy.layers.snmp import ASN1_NULL, SNMPvarbind
 
 from mb_netmgmt import mb, netconf, snmp, ssh, use_scalar_strings, yaml
@@ -287,3 +289,18 @@ def test_parse_to():
     assert parse_to("telnet://localhost:23").port == 23
     with pytest.raises(ValueError):
         parse_to("localhost")
+
+
+def test_to_varbind_with_base64encode_response():
+    result = snmp.to_varbind(
+        "1.3.6.1.2.1.1.2.0",
+        response=dict(val=b64encode(b"1.3.6.1.4.1.9.1.1709"), tag="OID"),
+    )
+    assert isinstance(result.value, ASN1_OID)
+
+
+def test_to_varbind_without_base64encode_response():
+    result = snmp.to_varbind(
+        "1.3.6.1.2.1.1.2.0", response=dict(val="1.3.6.1.4.1.9.1.1709", tag="OID")
+    )
+    assert isinstance(result.value, ASN1_OID)