Convert to async MIB instrumentation API (#209)
MIB instrumentation API changed to allow for asynchronous managed objects access. Although built-in SNMPv2-SMI objects are still synchronous, the MIB instrumentation API is async what allows users to replace default MIB instrumentation with their own, potentially asynchronous. CommandResponder refactored to facilitate asynchronous MIB instrumentation routines. The `readVars`, `readNextVars` and `writeVars` MIB controller methods return immediately and deliver their results via a call back. SMI/MIB managed objects API overhauled for simplicity and flexibility breaking backward compatibility.async-mib-fsm-methods
Ilya Etingof
GitHub
parent
12138b182c
commit
534a5bb810
24
CHANGES.txt
24
CHANGES.txt
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@ -5,9 +5,11 @@ Revision 5.0.0, released 2018-10-??
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- SNMPv3 crypto operations that require external dependencies
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made dependent on the optional external
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package -- pysnmpcrypto.
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- By switching to pysnmpcrypto, pysnmp effectively migrates from
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PyCryptodomex to pyca/cryptography whenever available on the
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platform.
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- Many really old backward-compatibility code snippets removed.
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Most importantly:
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@ -19,13 +21,20 @@ Revision 5.0.0, released 2018-10-??
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- The MIB instrumentation API overhauled in backward incompatible
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way:
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- MIB instrumentation methods signatures simplified to accept
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just var-binds (as var-arg), the rest of the parameters packed
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into opaque kwargs
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- CommandResponder application passes `snmpEngine` and optionally
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user-supplied `cbCtx` object throughout the MIB instrumentation
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methods. The goal is to let MIB objects access/modify whatever
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custom Python objects they need while being called back.
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* MIB instrumentation methods signatures simplified to accept
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just var-binds (as var-arg), the rest of the parameters packed
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into opaque kwargs
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* CommandResponder application passes `snmpEngine` and optionally
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user-supplied `cbCtx` object throughout the MIB instrumentation
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methods. The goal is to let MIB objects access/modify whatever
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custom Python objects they need while being called back.
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* CommandResponder refactored to facilitate asynchronous
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MIB instrumentation routines. The `readVars`, `readNextVars` and
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`writeVars` MIB controller methods return immediately and
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deliver their results via a call back.
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- The high-level API (`hlapi`) extended to cover lightweight SNMP v1arch
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in hope to ease the use of packet-level SNMP API.
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@ -41,6 +50,7 @@ Revision 5.0.0, released 2018-10-??
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automation around building well-formed SNMP messages is and mediating
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differences between SNMP versions is not present in this new `v1arch`
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layer.
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- The signature of the hlapi `.sendNotification()` call has changed
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to accept `*varBinds` instead of a sequence of `varBinds`. The rationale
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is to unify this method call with similar methods of CommandGenerator.
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@ -51,13 +51,23 @@ if __name__ == '__main__':
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mibInstrum = instrum.MibInstrumController(mibBuilder)
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def cbFun(varBinds, **context):
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for oid, val in varBinds:
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if exval.endOfMib.isSameTypeWith(val):
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context['state']['stop'] = True
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print('%s = %s' % ('.'.join([str(x) for x in oid]), not val.isValue and 'N/A' or val.prettyPrint()))
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context['state']['varBinds'] = varBinds
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context = {
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'cbFun': cbFun,
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'state': {
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'varBinds': [((1, 3, 6), None)],
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'stop': False
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}
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}
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print('Remote manager read access to MIB instrumentation (table walk)')
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varBinds = [((), None)]
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while True:
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varBinds = mibInstrum.readNextVars(*varBinds)
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oid, val = varBinds[0]
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if exval.endOfMib.isSameTypeWith(val):
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break
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print(oid, val.prettyPrint())
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while not context['state']['stop']:
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mibInstrum.readNextVars(*context['state']['varBinds'], **context)
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print('done')
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@ -26,24 +26,40 @@ snmpCommunityEntry, = mibBuilder.importSymbols(
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instanceId = snmpCommunityEntry.getInstIdFromIndices('my-router')
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print('done')
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def cbFun(varBinds, **context):
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for oid, val in varBinds:
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print('%s = %s' % ('.'.join([str(x) for x in oid]), not val.isValue and 'N/A' or val.prettyPrint()))
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print('Create/update SNMP-COMMUNITY-MIB::snmpCommunityEntry table row: ')
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varBinds = mibInstrum.writeVars(
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mibInstrum.writeVars(
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(snmpCommunityEntry.name + (2,) + instanceId, 'mycomm'),
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(snmpCommunityEntry.name + (3,) + instanceId, 'mynmsname'),
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(snmpCommunityEntry.name + (7,) + instanceId, 'volatile')
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(snmpCommunityEntry.name + (7,) + instanceId, 'volatile'),
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cbFun=cbFun
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)
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for oid, val in varBinds:
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print('%s = %s' % ('.'.join([str(x) for x in oid]), not val.isValue and 'N/A' or val.prettyPrint()))
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print('done')
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def cbFun(varBinds, **context):
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for oid, val in varBinds:
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if exval.endOfMib.isSameTypeWith(val):
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context['state']['stop'] = True
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print('%s = %s' % ('.'.join([str(x) for x in oid]), not val.isValue and 'N/A' or val.prettyPrint()))
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context['state']['varBinds'] = varBinds
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context = {
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'cbFun': cbFun,
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'state': {
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'varBinds': [((1, 3, 6), None)],
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'stop': False
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}
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}
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print('Read whole MIB (table walk)')
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varBinds = [((), None)]
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while True:
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varBinds = mibInstrum.readNextVars(*varBinds)
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oid, val = varBinds[0]
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if exval.endOfMib.isSameTypeWith(val):
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break
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print('%s = %s' % ('.'.join([str(x) for x in oid]), not val.isValue and 'N/A' or val.prettyPrint()))
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while not context['state']['stop']:
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mibInstrum.readNextVars(*context['state']['varBinds'], **context)
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print('done')
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print('Unloading MIB modules...'),
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@ -54,7 +54,9 @@ snmpContext = context.SnmpContext(snmpEngine)
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# always echos request var-binds in response.
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class EchoMibInstrumController(instrum.AbstractMibInstrumController):
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def readVars(self, *varBinds, **context):
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return [(ov[0], v2c.OctetString('You queried OID %s' % ov[0])) for ov in varBinds]
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cbFun = context.get('cbFun')
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if cbFun:
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cbFun([(ov[0], v2c.OctetString('You queried OID %s' % ov[0])) for ov in varBinds], **context)
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# Create a custom Management Instrumentation Controller and register at
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@ -422,7 +422,8 @@ def delContext(snmpEngine, contextName):
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vacmContextEntry, tblIdx = __cookVacmContextInfo(snmpEngine, contextName)
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snmpEngine.msgAndPduDsp.mibInstrumController.writeVars(
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(vacmContextEntry.name + (2,) + tblIdx, 'destroy')
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(vacmContextEntry.name + (2,) + tblIdx, 'destroy'),
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** dict(snmpEngine=snmpEngine)
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)
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@ -25,8 +25,7 @@ class CommandResponderBase(object):
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self.cbCtx = cbCtx
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self.__pendingReqs = {}
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def handleMgmtOperation(self, snmpEngine, stateReference,
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contextName, PDU, acCtx):
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def initiateMgmtOperation(self, snmpEngine, stateReference, contextName, PDU):
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pass
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def close(self, snmpEngine):
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@ -147,7 +146,7 @@ class CommandResponderBase(object):
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'processPdu: stateReference %s, varBinds %s' % (stateReference, varBinds))
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try:
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self.handleMgmtOperation(snmpEngine, stateReference, contextName, PDU)
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self.initiateMgmtOperation(snmpEngine, stateReference, contextName, PDU)
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# SNMPv2 SMI exceptions
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except pysnmp.smi.error.GenError:
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@ -263,53 +262,79 @@ class CommandResponderBase(object):
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class GetCommandResponder(CommandResponderBase):
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pduTypes = (rfc1905.GetRequestPDU.tagSet,)
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def completeMgmtOperation(self, varBinds, **context):
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self.sendVarBinds(context['snmpEngine'], context['stateReference'],
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0, 0, varBinds)
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self.releaseStateInformation(context['stateReference'])
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# rfc1905: 4.2.1
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def handleMgmtOperation(self, snmpEngine, stateReference, contextName, PDU):
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def initiateMgmtOperation(self, snmpEngine, stateReference, contextName, PDU):
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# rfc1905: 4.2.1.1
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mgmtFun = self.snmpContext.getMibInstrum(contextName).readVars
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varBinds = v2c.apiPDU.getVarBinds(PDU)
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context = dict(snmpEngine=snmpEngine, acFun=self.verifyAccess, cbCtx=self.cbCtx)
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context = dict(snmpEngine=snmpEngine,
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stateReference=stateReference,
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acFun=self.verifyAccess,
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cbFun=self.completeMgmtOperation,
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cbCtx=self.cbCtx)
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rspVarBinds = mgmtFun(*varBinds, **context)
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self.sendVarBinds(snmpEngine, stateReference, 0, 0, rspVarBinds)
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self.releaseStateInformation(stateReference)
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mgmtFun(*varBinds, **context)
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class NextCommandResponder(CommandResponderBase):
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pduTypes = (rfc1905.GetNextRequestPDU.tagSet,)
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def completeMgmtOperation(self, varBinds, **context):
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self.sendVarBinds(context['snmpEngine'], context['stateReference'],
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0, 0, varBinds)
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self.releaseStateInformation(context['stateReference'])
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# rfc1905: 4.2.2
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def handleMgmtOperation(self, snmpEngine, stateReference, contextName, PDU):
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def initiateMgmtOperation(self, snmpEngine, stateReference, contextName, PDU):
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# rfc1905: 4.2.2.1
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mgmtFun = self.snmpContext.getMibInstrum(contextName).readNextVars
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varBinds = v2c.apiPDU.getVarBinds(PDU)
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context = dict(snmpEngine=snmpEngine, acFun=self.verifyAccess, cbCtx=self.cbCtx)
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context = dict(snmpEngine=snmpEngine,
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stateReference=stateReference,
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acFun=self.verifyAccess,
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cbFun=self.completeMgmtOperation,
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cbCtx=self.cbCtx)
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while True:
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rspVarBinds = mgmtFun(*varBinds, **context)
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try:
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self.sendVarBinds(snmpEngine, stateReference, 0, 0, rspVarBinds)
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except error.StatusInformation:
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idx = sys.exc_info()[1]['idx']
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varBinds[idx] = (rspVarBinds[idx][0], varBinds[idx][1])
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else:
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break
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self.releaseStateInformation(stateReference)
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mgmtFun(*varBinds, **context)
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class BulkCommandResponder(CommandResponderBase):
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pduTypes = (rfc1905.GetBulkRequestPDU.tagSet,)
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maxVarBinds = 64
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def _completeNonRepeaters(self, varBinds, **context):
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context['rspVarBinds'][:] = varBinds
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context['cbFun'] = self.completeMgmtOperation
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mgmtFun = self.snmpContext.getMibInstrum(context['contextName']).readNextVars
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mgmtFun(*context['varBinds'], **context)
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def completeMgmtOperation(self, varBinds, **context):
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context['rspVarBinds'].extend(varBinds)
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context['counters']['M'] -= 1
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if context['counters']['M'] and context['counters']['R']:
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mgmtFun = self.snmpContext.getMibInstrum(context['contextName']).readNextVars
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context['cbFun'] = self.completeMgmtOperation
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mgmtFun(*varBinds[-context['counters']['R']:], **context)
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else:
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self.sendVarBinds(context['snmpEngine'], context['stateReference'],
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0, 0, varBinds)
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self.releaseStateInformation(context['stateReference'])
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# rfc1905: 4.2.3
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def handleMgmtOperation(self, snmpEngine, stateReference, contextName, PDU):
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def initiateMgmtOperation(self, snmpEngine, stateReference, contextName, PDU):
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nonRepeaters = v2c.apiBulkPDU.getNonRepeaters(PDU)
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if nonRepeaters < 0:
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nonRepeaters = 0
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@ -318,68 +343,60 @@ class BulkCommandResponder(CommandResponderBase):
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if maxRepetitions < 0:
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maxRepetitions = 0
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reqVarBinds = v2c.apiPDU.getVarBinds(PDU)
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varBinds = v2c.apiPDU.getVarBinds(PDU)
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N = min(int(nonRepeaters), len(reqVarBinds))
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N = min(int(nonRepeaters), len(varBinds))
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M = int(maxRepetitions)
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R = max(len(reqVarBinds) - N, 0)
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R = max(len(varBinds) - N, 0)
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if R:
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M = min(M, self.maxVarBinds // R)
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debug.logger & debug.flagApp and debug.logger('handleMgmtOperation: N %d, M %d, R %d' % (N, M, R))
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debug.logger & debug.flagApp and debug.logger(
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'initiateMgmtOperation: N %d, M %d, R %d' % (N, M, R))
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mgmtFun = self.snmpContext.getMibInstrum(contextName).readNextVars
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context = dict(snmpEngine=snmpEngine, acFun=self.verifyAccess, cbCtx=self.cbCtx)
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context = dict(snmpEngine=snmpEngine,
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stateReference=stateReference,
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contextName=contextName,
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acFun=self.verifyAccess,
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cbFun=self._completeNonRepeaters,
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cbCtx=self.cbCtx,
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varBinds=varBinds[-R:],
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counters={'M': M, 'R': R},
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rspVarBinds=[])
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if N:
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# TODO(etingof): manage all PDU var-binds in a single call
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rspVarBinds = mgmtFun(*reqVarBinds[:N], **context)
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else:
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rspVarBinds = []
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varBinds = reqVarBinds[-R:]
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while M and R:
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rspVarBinds.extend(mgmtFun(*varBinds, **context))
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varBinds = rspVarBinds[-R:]
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M -= 1
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if len(rspVarBinds):
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self.sendVarBinds(snmpEngine, stateReference, 0, 0, rspVarBinds)
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self.releaseStateInformation(stateReference)
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else:
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raise pysnmp.smi.error.SmiError()
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mgmtFun(*varBinds[:N], **context)
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class SetCommandResponder(CommandResponderBase):
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pduTypes = (rfc1905.SetRequestPDU.tagSet,)
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def completeMgmtOperation(self, varBinds, **context):
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self.sendVarBinds(context['snmpEngine'], context['stateReference'],
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0, 0, varBinds)
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self.releaseStateInformation(context['stateReference'])
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# rfc1905: 4.2.5
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def handleMgmtOperation(self, snmpEngine, stateReference, contextName, PDU):
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def initiateMgmtOperation(self, snmpEngine, stateReference, contextName, PDU):
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mgmtFun = self.snmpContext.getMibInstrum(contextName).writeVars
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varBinds = v2c.apiPDU.getVarBinds(PDU)
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instrumError = None
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context = dict(snmpEngine=snmpEngine, acFun=self.verifyAccess, cbCtx=self.cbCtx)
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context = dict(snmpEngine=snmpEngine,
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stateReference=stateReference,
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acFun=self.verifyAccess,
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cbFun=self.completeMgmtOperation,
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cbCtx=self.cbCtx)
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# rfc1905: 4.2.5.1-13
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try:
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rspVarBinds = mgmtFun(*varBinds, **context)
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mgmtFun(*varBinds, **context)
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except (pysnmp.smi.error.NoSuchObjectError,
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pysnmp.smi.error.NoSuchInstanceError):
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instrumError = pysnmp.smi.error.NotWritableError()
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instrumError.update(sys.exc_info()[1])
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else:
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self.sendVarBinds(snmpEngine, stateReference, 0, 0, rspVarBinds)
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self.releaseStateInformation(stateReference)
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if instrumError:
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self.releaseStateInformation(stateReference)
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raise instrumError
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@ -184,15 +184,25 @@ class MibInstrumController(AbstractMibInstrumController):
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# MIB instrumentation
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def flipFlopFsm(self, fsmTable, *varBinds, **context):
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self.__indexMib()
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debug.logger & debug.flagIns and debug.logger('flipFlopFsm: input var-binds %r' % (varBinds,))
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try:
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fsmContext = context['fsmState']
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except KeyError:
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self.__indexMib()
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fsmContext = context['fsmState'] = dict(varBinds=[], state='start', status='ok')
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debug.logger & debug.flagIns and debug.logger('flipFlopFsm: input var-binds %r' % (varBinds,))
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mibTree, = self.mibBuilder.importSymbols('SNMPv2-SMI', 'iso')
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outputVarBinds = []
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state, status = 'start', 'ok'
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outputVarBinds = fsmContext['varBinds']
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state = fsmContext['state']
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status = fsmContext['status']
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origExc = origTraceback = None
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while True:
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k = state, status
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if k in fsmTable:
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@ -237,7 +247,7 @@ class MibInstrumController(AbstractMibInstrumController):
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break
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else:
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debug.logger & debug.flagIns and debug.logger(
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'flipFlopFsm: fun %s suceeded for %s=%r' % (mgmtFun, name, val))
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'flipFlopFsm: fun %s succeeded for %s=%r' % (mgmtFun, name, val))
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if rval is not None:
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outputVarBinds.append((rval[0], rval[1]))
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@ -252,13 +262,15 @@ class MibInstrumController(AbstractMibInstrumController):
|
|||
# (seems to be irrelevant on Py3 but just in case)
|
||||
del origTraceback
|
||||
|
||||
return outputVarBinds
|
||||
cbFun = context.get('cbFun')
|
||||
if cbFun:
|
||||
cbFun(outputVarBinds, **context)
|
||||
|
||||
def readVars(self, *varBinds, **context):
|
||||
return self.flipFlopFsm(self.fsmReadVar, *varBinds, **context)
|
||||
self.flipFlopFsm(self.fsmReadVar, *varBinds, **context)
|
||||
|
||||
def readNextVars(self, *varBinds, **context):
|
||||
return self.flipFlopFsm(self.fsmReadNextVar, *varBinds, **context)
|
||||
self.flipFlopFsm(self.fsmReadNextVar, *varBinds, **context)
|
||||
|
||||
def writeVars(self, *varBinds, **context):
|
||||
return self.flipFlopFsm(self.fsmWriteVar, *varBinds, **context)
|
||||
self.flipFlopFsm(self.fsmWriteVar, *varBinds, **context)
|
||||
|
|
|
|||
Loading…
Reference in New Issue