fix to non-MT-safe class attributes at SNMPv3 MP & SEC modules

3 files changed, 8 insertions, 7 deletions

diff --git a/CHANGES b/CHANGES
index 1a0e9f6..7ec28f6 100644
--- a/CHANGES
+++ b/CHANGES
@@ -26,6 +26,7 @@ Revision 4.2.2
 - When running on Python3, SMI will re-raise exceptions with the original
   traceback for easier diagnostics.
 - Out of PYTHONPATH MIB paths now supported.
+- Fix to non-MT-safe class attributes at SNMPv3 MP & SEC modules.
 - Fix to ContextName handling in bytes form whilst running Python3. Data
   mismatch error would return otherwise.
 - Fix to socket.error processing at Py3 on Windows.
diff --git a/pysnmp/proto/mpmod/rfc3412.py b/pysnmp/proto/mpmod/rfc3412.py
index 801fcbe..a34f8b9 100644
--- a/pysnmp/proto/mpmod/rfc3412.py
+++ b/pysnmp/proto/mpmod/rfc3412.py
@@ -55,7 +55,6 @@ _snmpErrors = {
 class SnmpV3MessageProcessingModel(AbstractMessageProcessingModel):
     messageProcessingModelID = univ.Integer(3) # SNMPv3
     snmpMsgSpec = SNMPv3Message
-    _scopedPDU = ScopedPDU()
     _emptyStr = univ.OctetString('')
     _msgFlags = {
         0: univ.OctetString('\x00'),
@@ -67,6 +66,7 @@ class SnmpV3MessageProcessingModel(AbstractMessageProcessingModel):
         }
     def __init__(self):
         AbstractMessageProcessingModel.__init__(self)
+        self.__scopedPDU = ScopedPDU()
         self.__engineIDs = {}
         self.__engineIDsExpQueue = {}
         self.__expirationTimer = 0
@@ -122,7 +122,7 @@ class SnmpV3MessageProcessingModel(AbstractMessageProcessingModel):
         debug.logger & debug.flagMP and debug.logger('prepareOutgoingMessage: using contextEngineId %r, contextName %r' % (contextEngineId, contextName))
         
         # 7.1.6
-        scopedPDU = self._scopedPDU
+        scopedPDU = self.__scopedPDU
         scopedPDU.setComponentByPosition(0, contextEngineId)
         scopedPDU.setComponentByPosition(1, contextName)
         scopedPDU.setComponentByPosition(2)
@@ -196,7 +196,7 @@ class SnmpV3MessageProcessingModel(AbstractMessageProcessingModel):
                     2, self._msgFlags[msgFlags & 0xfc], verifyConstraints=False
                     )
                 # XXX
-                scopedPDU = self._scopedPDU
+                scopedPDU = self.__scopedPDU
                 scopedPDU.setComponentByPosition(
                     0, self._emptyStr, verifyConstraints=False
                     )
@@ -352,7 +352,7 @@ class SnmpV3MessageProcessingModel(AbstractMessageProcessingModel):
         debug.logger & debug.flagMP and debug.logger('prepareResponseMessage: using contextEngineId %r, contextName %r' % (contextEngineId, contextName))
 
         # 7.1.6
-        scopedPDU = self._scopedPDU
+        scopedPDU = self.__scopedPDU
         scopedPDU.setComponentByPosition(0, contextEngineId)
         scopedPDU.setComponentByPosition(1, contextName)
         scopedPDU.setComponentByPosition(2)
diff --git a/pysnmp/proto/secmod/rfc3414/service.py b/pysnmp/proto/secmod/rfc3414/service.py
index 2b614d1..586f6a3 100644
--- a/pysnmp/proto/secmod/rfc3414/service.py
+++ b/pysnmp/proto/secmod/rfc3414/service.py
@@ -40,9 +40,9 @@ class SnmpUSMSecurityModel(AbstractSecurityModel):
         aes256.Aes256.serviceID: aes256.Aes256(),
         nopriv.NoPriv.serviceID: nopriv.NoPriv()
         }
-    _securityParametersSpec = UsmSecurityParameters()
     def __init__(self):
         AbstractSecurityModel.__init__(self)
+        self.__securityParametersSpec = UsmSecurityParameters()
         self.__timeline = {}
         self.__timelineExpQueue = {}
         self.__expirationTimer = 0
@@ -277,7 +277,7 @@ class SnmpUSMSecurityModel(AbstractSecurityModel):
                     errorIndication = errind.unsupportedSecurityLevel
                     )
 
-        securityParameters = self._securityParametersSpec
+        securityParameters = self.__securityParametersSpec
 
         scopedPDUData = msg.setComponentByPosition(3).getComponentByPosition(3)
         scopedPDUData.setComponentByPosition(
@@ -487,7 +487,7 @@ class SnmpUSMSecurityModel(AbstractSecurityModel):
         try:
             securityParameters, rest = decoder.decode(
                 securityParameters,
-                asn1Spec=self._securityParametersSpec
+                asn1Spec=self.__securityParametersSpec
                 )
         except PyAsn1Error:
            snmpInASNParseErrs, = snmpEngine.msgAndPduDsp.mibInstrumController.mibBuilder.importSymbols('__SNMPv2-MIB', 'snmpInASNParseErrs')