Add SNMPv3 support to nav.Snmp.pynetsnmp implementation #2703

python/nav/Snmp/defines.py

@@ -0,0 +1,43 @@
+#
+# Copyright (C) 2023 Sikt
+#
+# This file is part of Network Administration Visualized (NAV).
+#
+# NAV is free software: you can redistribute it and/or modify it under
+# the terms of the GNU General Public License version 3 as published by
+# the Free Software Foundation.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT
+# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+# FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+# more details.  You should have received a copy of the GNU General Public
+# License along with NAV. If not, see <http://www.gnu.org/licenses/>.
+#
+"""Defines types and enumerations for SNMP communication parameters"""
+from enum import Enum
+
+
+class SecurityLevel(Enum):
+    """SNMPv3 security levels"""
+
+    NO_AUTH_NO_PRIV = "noAuthNoPriv"
+    AUTH_NO_PRIV = "authNoPriv"
+    AUTH_PRIV = "authPriv"
+
+
+class AuthenticationProtocol(Enum):
+    """SNMPv3 authentication protocols supported by NET-SNMP"""
+
+    MD5 = "MD5"
+    SHA = "SHA"
+    SHA512 = "SHA-512"
+    SHA384 = "SHA-384"
+    SHA256 = "SHA-256"
+    SHA224 = "SHA-224"
+
+
+class PrivacyProtocol(Enum):
+    """SNMPv3 privacy protocols supported by NET-SNMP"""
+
+    DES = "DES"
+    AES = "AES"

python/nav/Snmp/errors.py

@@ -31,3 +31,7 @@ class UnsupportedSnmpVersionError(SnmpError):
 
 class NoSuchObjectError(SnmpError):
     """SNMP agent did not know of this object"""
+
+
+class SNMPv3ConfigurationError(SnmpError):
+    """Error in SNMPv3 configuration parameters"""

python/nav/Snmp/pynetsnmp.py

@@ -31,6 +31,7 @@
     c_ulong,
     c_uint64,
 )
+from typing import Union, Optional
 
 from IPy import IP
 from pynetsnmp import netsnmp
@@ -48,12 +49,14 @@
 )
 
 from nav.oids import OID
+from .defines import SecurityLevel, AuthenticationProtocol, PrivacyProtocol
 from .errors import (
     EndOfMibViewError,
     NoSuchObjectError,
     SnmpError,
     TimeOutException,
     UnsupportedSnmpVersionError,
+    SNMPv3ConfigurationError,
 )
 
 PDUVarbind = namedtuple("PDUVarbind", ['oid', 'type', 'value'])
@@ -85,30 +88,86 @@ class Snmp(object):
     """
 
     def __init__(
-        self, host, community="public", version="1", port=161, retries=3, timeout=1
+        self,
+        host: str,
+        community: str = "public",
+        version: Union[str, int] = "1",
+        port: Union[str, int] = 161,
+        retries: int = 3,
+        timeout: int = 1,
+        # SNMPv3-only options
+        sec_level: Optional[SecurityLevel] = None,
+        auth_protocol: Optional[AuthenticationProtocol] = None,
+        sec_name: Optional[str] = None,
+        auth_password: Optional[str] = None,
+        priv_protocol: Optional[PrivacyProtocol] = None,
+        priv_password: Optional[str] = None,
     ):
         """Makes a new Snmp-object.
 
         :param host: hostname or IP address
         :param community: community (password), defaults to "public"
         :param port: udp port number, defaults to "161"
+        :param sec_level: SNMPv3 security level
+        :param auth_protocol: SNMPv3 authentication protocol
+        :param sec_name: SNMPv3 securityName
+        :param auth_password: SNMPv3 authentication password
+        :param priv_protocol: SNMPv3 privacy protocol
+        :param priv_password: SNMPv3 privacy password
 
         """
-
+        self.handle = None
         self.host = host
         self.community = str(community)
         self.version = str(version)
         if self.version == '2':
             self.version = '2c'
-        if self.version not in ('1', '2c'):
+        if self.version not in ('1', '2c', '3'):
             raise UnsupportedSnmpVersionError(self.version)
         self.port = int(port)
         self.retries = retries
         self.timeout = timeout
 
+        self.sec_level = SecurityLevel(sec_level) if sec_level else None
+        self.auth_protocol = (
+            AuthenticationProtocol(auth_protocol) if auth_protocol else None
+        )
+        self.sec_name = sec_name
+        self.auth_password = auth_password
+        self.priv_protocol = PrivacyProtocol(priv_protocol) if priv_protocol else None
+        self.priv_password = priv_password
+        if self.version == "3":
+            self._verify_snmpv3_params()
+
         self.handle = _MySnmpSession(self._build_cmdline())
         self.handle.open()
 
+    def _verify_snmpv3_params(self):
+        if not self.sec_level:
+            raise SNMPv3ConfigurationError("sec_level is required to be set")
+        if not self.sec_name:
+            raise SNMPv3ConfigurationError(
+                "sec_name is required regardless of security level"
+            )
+        if self.sec_level in (SecurityLevel.AUTH_NO_PRIV, SecurityLevel.AUTH_PRIV):
+            if not self.auth_protocol:
+                raise SNMPv3ConfigurationError(
+                    f"{self.sec_level.value} requires auth_protocol to be set"
+                )
+            if not self.auth_password:
+                raise SNMPv3ConfigurationError(
+                    f"{self.sec_level.value} requires auth_password to be set"
+                )
+        if self.sec_level == SecurityLevel.AUTH_PRIV:
+            if not self.priv_protocol:
+                raise SNMPv3ConfigurationError(
+                    f"{self.sec_level.value} requires priv_protocol to be set"
+                )
+            if not self.priv_password:
+                raise SNMPv3ConfigurationError(
+                    f"{self.sec_level.value} requires priv_password to be set"
+                )
+
     def _build_cmdline(self):
         try:
             address = IP(self.host)
@@ -117,19 +176,29 @@ def _build_cmdline(self):
         else:
             host = 'udp6:[%s]' % self.host if address.version() == 6 else self.host
 
-        return (
-            '-v' + self.version,
-            '-c',
-            self.community,
-            '-r',
-            str(self.retries),
-            '-t',
-            str(self.timeout),
-            '%s:%s' % (host, self.port),
+        params = [f"-v{self.version}"]
+
+        if self.version in ("1", "2c"):
+            params.extend(["-c", self.community])
+        elif self.version == "3":
+            params.extend(["-l", self.sec_level.value, "-u", self.sec_name])
+            if self.auth_protocol:
+                params.extend(["-a", self.auth_protocol.value])
+            if self.auth_password:
+                params.extend(["-A", self.auth_password])
+            if self.priv_protocol:
+                params.extend(["-x", self.priv_protocol.value])
+            if self.priv_password:
+                params.extend(["-X", self.priv_password])
+
+        params.extend(
+            ["-r", str(self.retries), "-t", str(self.timeout), f"{host}:{self.port}"]
         )
+        return tuple(params)
 
     def __del__(self):
-        self.handle.close()
+        if self.handle:
+            self.handle.close()
 
     def get(self, query="1.3.6.1.2.1.1.1.0"):
         """Performs an SNMP GET query.