| # CER decoder |
| from pyasn1.type import univ |
| from pyasn1.codec.ber import decoder |
| from pyasn1.compat.octets import oct2int |
| from pyasn1 import error |
| |
| class BooleanDecoder(decoder.AbstractSimpleDecoder): |
| protoComponent = univ.Boolean(0) |
| def valueDecoder(self, fullSubstrate, substrate, asn1Spec, tagSet, length, |
| state, decodeFun, substrateFun): |
| head, tail = substrate[:length], substrate[length:] |
| if not head: |
| raise error.PyAsn1Error('Empty substrate') |
| byte = oct2int(head[0]) |
| # CER/DER specifies encoding of TRUE as 0xFF and FALSE as 0x0, while |
| # BER allows any non-zero value as TRUE; cf. sections 8.2.2. and 11.1 |
| # in http://www.itu.int/ITU-T/studygroups/com17/languages/X.690-0207.pdf |
| if byte == 0xff: |
| value = 1 |
| elif byte == 0x00: |
| value = 0 |
| else: |
| raise error.PyAsn1Error('Boolean CER violation: %s' % byte) |
| return self._createComponent(asn1Spec, tagSet, value), tail |
| |
| tagMap = decoder.tagMap.copy() |
| tagMap.update({ |
| univ.Boolean.tagSet: BooleanDecoder() |
| }) |
| |
| typeMap = decoder.typeMap |
| |
| class Decoder(decoder.Decoder): pass |
| |
| decode = Decoder(tagMap, decoder.typeMap) |
