#!/usr/bin/env python
#
# SNMPv3 message syntax
#
# ASN.1 source from:
# http://www.ietf.org/rfc/rfc3412.txt
#
from pyasn1.type import univ, namedtype, namedval, tag, constraint
from pyasn1_modules import rfc1905

class ScopedPDU(univ.Sequence):
    componentType = namedtype.NamedTypes(
        namedtype.NamedType('contextEngineId', univ.OctetString()),
        namedtype.NamedType('contextName', univ.OctetString()),
        namedtype.NamedType('data', rfc1905.PDUs())
        )
    
class ScopedPduData(univ.Choice):
    componentType = namedtype.NamedTypes(
        namedtype.NamedType('plaintext', ScopedPDU()),
        namedtype.NamedType('encryptedPDU', univ.OctetString()),
        )
    
class HeaderData(univ.Sequence):
    componentType = namedtype.NamedTypes(
        namedtype.NamedType('msgID', univ.Integer().subtype(subtypeSpec=constraint.ValueRangeConstraint(0, 2147483647))),
        namedtype.NamedType('msgMaxSize', univ.Integer().subtype(subtypeSpec=constraint.ValueRangeConstraint(484, 2147483647))),
        namedtype.NamedType('msgFlags', univ.OctetString().subtype(subtypeSpec=constraint.ValueSizeConstraint(1, 1))),
        namedtype.NamedType('msgSecurityModel', univ.Integer().subtype(subtypeSpec=constraint.ValueRangeConstraint(1, 2147483647)))
        )

class SNMPv3Message(univ.Sequence):
    componentType = namedtype.NamedTypes(
         namedtype.NamedType('msgVersion', univ.Integer().subtype(subtypeSpec=constraint.ValueRangeConstraint(0, 2147483647))),
         namedtype.NamedType('msgGlobalData', HeaderData()),
         namedtype.NamedType('msgSecurityParameters', univ.OctetString()),
         namedtype.NamedType('msgData', ScopedPduData())
         )

