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Reformat `isAccessAllowed()` for clarity

async-mib-instrumentation
Ilya Etingof 2018-10-06 09:29:29 +02:00
parent 35e9c6f7a6
commit 593ff19283
1 changed files with 30 additions and 13 deletions
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43
pysnmp/proto/acmod/rfc3415.py
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@ -8,14 +8,14 @@ from pysnmp.smi.error import NoSuchInstanceError
from pysnmp.proto import errind, error
from pysnmp import debug
__powOfTwoSeq = [128, 64, 32, 16, 8, 4, 2, 1]
# 3.2
class Vacm(object):
"""View-based Access Control Model"""
accessModelID = 3
_powOfTwoSeq = (128, 64, 32, 16, 8, 4, 2, 1)
def isAccessAllowed(self,
snmpEngine,
securityModel,
@ -31,25 +31,30 @@ class Vacm(object):
securityModel, securityName, securityLevel, viewType, contextName, variableName))
# 3.2.1
vacmContextEntry, = mibInstrumController.mibBuilder.importSymbols('SNMP-VIEW-BASED-ACM-MIB', 'vacmContextEntry')
vacmContextEntry, = mibInstrumController.mibBuilder.importSymbols(
'SNMP-VIEW-BASED-ACM-MIB', 'vacmContextEntry')
tblIdx = vacmContextEntry.getInstIdFromIndices(contextName)
try:
vacmContextName = vacmContextEntry.getNode(
vacmContextEntry.getNode(
vacmContextEntry.name + (1,) + tblIdx
).syntax
except NoSuchInstanceError:
raise error.StatusInformation(errorIndication=errind.noSuchContext)
# 3.2.2
vacmSecurityToGroupEntry, = mibInstrumController.mibBuilder.importSymbols('SNMP-VIEW-BASED-ACM-MIB',
'vacmSecurityToGroupEntry')
vacmSecurityToGroupEntry, = mibInstrumController.mibBuilder.importSymbols(
'SNMP-VIEW-BASED-ACM-MIB', 'vacmSecurityToGroupEntry')
tblIdx = vacmSecurityToGroupEntry.getInstIdFromIndices(
securityModel, securityName
)
try:
vacmGroupName = vacmSecurityToGroupEntry.getNode(
vacmSecurityToGroupEntry.name + (3,) + tblIdx
).syntax
except NoSuchInstanceError:
raise error.StatusInformation(errorIndication=errind.noGroupName)
@ -57,6 +62,7 @@ class Vacm(object):
vacmAccessEntry, = mibInstrumController.mibBuilder.importSymbols(
'SNMP-VIEW-BASED-ACM-MIB', 'vacmAccessEntry'
)
# XXX partial context name match
tblIdx = vacmAccessEntry.getInstIdFromIndices(
vacmGroupName, contextName, securityModel, securityLevel
@ -74,51 +80,62 @@ class Vacm(object):
try:
viewName = vacmAccessEntry.getNode(entryIdx).syntax
except NoSuchInstanceError:
raise error.StatusInformation(errorIndication=errind.noAccessEntry)
if not len(viewName):
if not viewName:
raise error.StatusInformation(errorIndication=errind.noSuchView)
# XXX split onto object & instance ?
# 3.2.5a
vacmViewTreeFamilyEntry, = mibInstrumController.mibBuilder.importSymbols('SNMP-VIEW-BASED-ACM-MIB',
'vacmViewTreeFamilyEntry')
vacmViewTreeFamilyEntry, = mibInstrumController.mibBuilder.importSymbols(
'SNMP-VIEW-BASED-ACM-MIB', 'vacmViewTreeFamilyEntry')
tblIdx = vacmViewTreeFamilyEntry.getInstIdFromIndices(viewName)
# Walk over entries
initialTreeName = treeName = vacmViewTreeFamilyEntry.name + (2,) + tblIdx
maskName = vacmViewTreeFamilyEntry.name + (3,) + tblIdx
while 1:
while True:
vacmViewTreeFamilySubtree = vacmViewTreeFamilyEntry.getNextNode(
treeName
)
vacmViewTreeFamilyMask = vacmViewTreeFamilyEntry.getNextNode(
maskName
)
treeName = vacmViewTreeFamilySubtree.name
maskName = vacmViewTreeFamilyMask.name
if initialTreeName != treeName[:len(initialTreeName)]:
# 3.2.5b
raise error.StatusInformation(errorIndication=errind.notInView)
l = len(vacmViewTreeFamilySubtree.syntax)
if l > len(variableName):
continue
if vacmViewTreeFamilyMask.syntax:
mask = []
for c in vacmViewTreeFamilyMask.syntax.asNumbers():
mask = mask + [b & c for b in __powOfTwoSeq]
mask.extend([b & c for b in self._powOfTwoSeq])
m = len(mask) - 1
idx = l - 1
while idx:
if idx > m or mask[idx] and \
vacmViewTreeFamilySubtree.syntax[idx] != variableName[idx]:
if (idx > m or mask[idx] and
vacmViewTreeFamilySubtree.syntax[idx] != variableName[idx]):
break
idx -= 1
if idx:
continue # no match
else: # no mask
if vacmViewTreeFamilySubtree.syntax != variableName[:l]:
continue # no match
# 3.2.5c
return error.StatusInformation(errorIndication=errind.accessAllowed)