re-use some of ASN.1 structures used in message processing for efficiency

4 files changed, 16 insertions, 13 deletions

diff --git a/pysnmp/proto/mpmod/base.py b/pysnmp/proto/mpmod/base.py
index 7951273..ff357f8 100644
--- a/pysnmp/proto/mpmod/base.py
+++ b/pysnmp/proto/mpmod/base.py
@@ -3,8 +3,10 @@ from pysnmp.proto import error
 
 class AbstractMessageProcessingModel:
     messageProcessingModelID = None
+    snmpMsgSpec = None
     __stateReference = __msgID = 0L
     def __init__(self):
+        self.snmpMsgSpec = self.snmpMsgSpec()  # local copy
         self.__msgIdIndex = {}
         self.__stateReferenceIndex = {}
         self.__sendPduHandleIdx = {}
diff --git a/pysnmp/proto/mpmod/rfc2576.py b/pysnmp/proto/mpmod/rfc2576.py
index 393ade4..f6922b0 100644
--- a/pysnmp/proto/mpmod/rfc2576.py
+++ b/pysnmp/proto/mpmod/rfc2576.py
@@ -14,7 +14,7 @@ from pysnmp import debug
 
 class SnmpV1MessageProcessingModel(AbstractMessageProcessingModel):
     messageProcessingModelID = 0 # SNMPv1
-    _snmpMsgSpec = v1.Message()
+    snmpMsgSpec = v1.Message
     # rfc3412: 7.1
     def prepareOutgoingMessage(
         self,
@@ -55,7 +55,7 @@ class SnmpV1MessageProcessingModel(AbstractMessageProcessingModel):
         # rfc3412: 7.1.6
         scopedPDU = ( contextEngineId, contextName, pdu )
 
-        msg = self._snmpMsgSpec.clone()
+        msg = self.snmpMsgSpec
         msg.setComponentByPosition(0, self.messageProcessingModelID)
         msg.setComponentByPosition(2)
         msg.getComponentByPosition(2).setComponentByType(pdu.tagSet, pdu)
@@ -166,7 +166,7 @@ class SnmpV1MessageProcessingModel(AbstractMessageProcessingModel):
 
         debug.logger & debug.flagMP and debug.logger('prepareResponseMessage: using contextEngineId %s contextName %s' % (repr(contextEngineId), contextName))
         
-        msg = self._snmpMsgSpec.clone()
+        msg = self._snmpMsgSpec
         msg.setComponentByPosition(0, messageProcessingModel)
         msg.setComponentByPosition(2)
         msg.getComponentByPosition(2).setComponentByType(pdu.tagSet, pdu)
@@ -215,7 +215,7 @@ class SnmpV1MessageProcessingModel(AbstractMessageProcessingModel):
         # rfc3412: 7.2.2 
         try:
             msg, restOfwholeMsg = decoder.decode(
-                wholeMsg, asn1Spec=self._snmpMsgSpec
+                wholeMsg, asn1Spec=self.snmpMsgSpec
                 )
         except PyAsn1Error:
             snmpInASNParseErrs, = snmpEngine.msgAndPduDsp.mibInstrumController.mibBuilder.importSymbols('__SNMPv2-MIB', 'snmpInASNParseErrs')
@@ -408,4 +408,4 @@ class SnmpV1MessageProcessingModel(AbstractMessageProcessingModel):
         
 class SnmpV2cMessageProcessingModel(SnmpV1MessageProcessingModel):
     messageProcessingModelID = 1 # SNMPv2c
-    _snmpMsgSpec = v2c.Message()
+    snmpMsgSpec = v2c.Message
diff --git a/pysnmp/proto/mpmod/rfc3412.py b/pysnmp/proto/mpmod/rfc3412.py
index 950badb..35c0844 100644
--- a/pysnmp/proto/mpmod/rfc3412.py
+++ b/pysnmp/proto/mpmod/rfc3412.py
@@ -53,7 +53,8 @@ _snmpErrors = {
 
 class SnmpV3MessageProcessingModel(AbstractMessageProcessingModel):
     messageProcessingModelID = 3 # SNMPv3
-    _snmpMsgSpec = SNMPv3Message()
+    snmpMsgSpec = SNMPv3Message
+    _scopedPDU = ScopedPDU()
     def __init__(self):
         AbstractMessageProcessingModel.__init__(self)
         self.__engineIDs = {}
@@ -111,7 +112,7 @@ class SnmpV3MessageProcessingModel(AbstractMessageProcessingModel):
         debug.logger & debug.flagMP and debug.logger('prepareOutgoingMessage: using contextEngineId %s, contextName %s' % (repr(contextEngineId), contextName))
         
         # 7.1.6
-        scopedPDU = ScopedPDU()
+        scopedPDU = self._scopedPDU
         scopedPDU.setComponentByPosition(0, contextEngineId)
         scopedPDU.setComponentByPosition(1, contextName)
         scopedPDU.setComponentByPosition(2)
@@ -120,7 +121,7 @@ class SnmpV3MessageProcessingModel(AbstractMessageProcessingModel):
             )
 
         # 7.1.7
-        msg = SNMPv3Message()
+        msg = self.snmpMsgSpec
         
         # 7.1.7a
         msg.setComponentByPosition(0, 3) # version
@@ -178,7 +179,7 @@ class SnmpV3MessageProcessingModel(AbstractMessageProcessingModel):
                 # Clear possible auth&priv flags
                 headerData.setComponentByPosition(2, chr(msgFlags & 0xfc))
                 # XXX
-                scopedPDU = ScopedPDU()
+                scopedPDU = self._scopedPDU
                 scopedPDU.setComponentByPosition(0, '')
                 scopedPDU.setComponentByPosition(1, contextName)
                 scopedPDU.setComponentByPosition(2)
@@ -332,7 +333,7 @@ class SnmpV3MessageProcessingModel(AbstractMessageProcessingModel):
         debug.logger & debug.flagMP and debug.logger('prepareResponseMessage: using contextEngineId %s, contextName %s' % (repr(contextEngineId), contextName))
 
         # 7.1.6
-        scopedPDU = ScopedPDU()
+        scopedPDU = self._scopedPDU
         scopedPDU.setComponentByPosition(0, contextEngineId)
         scopedPDU.setComponentByPosition(1, contextName)
         scopedPDU.setComponentByPosition(2)
@@ -341,7 +342,7 @@ class SnmpV3MessageProcessingModel(AbstractMessageProcessingModel):
             )
 
         # 7.1.7
-        msg = SNMPv3Message()
+        msg = self.snmpMsgSpec
         
         # 7.1.7a
         msg.setComponentByPosition(0, 3) # version
@@ -426,7 +427,7 @@ class SnmpV3MessageProcessingModel(AbstractMessageProcessingModel):
         # 7.2.2
         try:
             msg, restOfwholeMsg = decoder.decode(
-                wholeMsg, asn1Spec=self._snmpMsgSpec
+                wholeMsg, asn1Spec=self.snmpMsgSpec
                 )
         except PyAsn1Error:
             snmpInASNParseErrs, = snmpEngine.msgAndPduDsp.mibInstrumController.mibBuilder.importSymbols('__SNMPv2-MIB', 'snmpInASNParseErrs')
diff --git a/pysnmp/proto/secmod/rfc3414/service.py b/pysnmp/proto/secmod/rfc3414/service.py
index 1eda407..c052537 100644
--- a/pysnmp/proto/secmod/rfc3414/service.py
+++ b/pysnmp/proto/secmod/rfc3414/service.py
@@ -276,7 +276,7 @@ class SnmpUSMSecurityModel(AbstractSecurityModel):
                     errorIndication = errind.unsupportedSecurityLevel
                     )
 
-        securityParameters = UsmSecurityParameters()
+        securityParameters = self._securityParametersSpec
 
         scopedPDUData = msg.setComponentByPosition(3).getComponentByPosition(3)
         scopedPDUData.setComponentByPosition(0, scopedPDU)