def validate(self):
"""
Ensure the condition is valid according the local rules.
Checks the condition against the local subtypes (supported
condition types) and the local maximum fulfillment size.
Returns:
bool: Whether the condition is valid according to local rules.
"""
# Get class for type ID, throws on error
TypeRegistry.find_by_type_id(self.type_id)
# Subtypes can have at most 32 bits with current implementation
if len(self.subtypes) > Condition.MAX_SAFE_SUBTYPES:
raise ValueError('Subtypes too large to be safely represented')
# Assert all requested features are supported by this implementation
if any(subtype not in Condition.SUPPORTED_SUBTYPES
for subtype in self.subtypes):
raise ValueError('Condition requested unsupported feature suites')
# Assert the requested fulfillment size
# is supported by this implementation
if self.cost > Condition.MAX_COST:
raise ValueError(
'Condition requested too large of a max fulfillment size')
return True
def to_asn1_dict(self):
condition_type = TypeRegistry.find_by_type_id(self.type_id)
condition_class = condition_type['class']
payload = {'fingerprint': self.hash, 'cost': self.cost}
if condition_class.TYPE_CATEGORY == 'compound':
subtype_ids = [
TypeRegistry.find_by_name(subtype)['type_id']
for subtype in self.subtypes
]
bits = ['0' for bit in range(5)]
for subtype_id in subtype_ids:
bits[subtype_id] = '1'
bitstring = ''.join(bits).rstrip('0')
payload['subtypes'] = bitstring
return {condition_class.TYPE_ASN1: payload}
def serialize_uri(self):
"""
Generate the URI form encoding of this condition.
Turns the condition into a URI containing only URL-safe characters. This
format is convenient for passing around conditions in URLs, JSON and other text-based formats.
"cc:" BASE16(TYPE_ID) ":" BASE16(BITMASK) ":" BASE64URL(HASH) ":" BASE10(MAX_COST)
Returns:
string: Condition as a URI
"""
condition_type = TypeRegistry.find_by_type_id(self.type_id)
condition_class = TypeRegistry.find_by_type_id(self.type_id)['class']
include_subtypes = condition_class.TYPE_CATEGORY == 'compound'
uri = 'ni:///sha-256;{}?fpt={}&cost={}'.format(
base64_remove_padding(
base64.urlsafe_b64encode(self.hash)).decode(),
condition_type['name'],
self.cost,
)
if include_subtypes:
uri += '&subtypes=' + ','.join(sorted(self.subtypes))
return uri
def from_asn1_dict(asn1_dict):
asn1_type, value = asn1_dict.popitem()
registered_type = TypeRegistry.find_by_asn1_type(asn1_type)
# Instantiate condition
condition = Condition()
condition.type_id = registered_type['type_id']
condition.hash = value['fingerprint']
condition.cost = value['cost']
condition._subtypes = set()
if registered_type['class'].TYPE_CATEGORY == 'compound':
subtypes = {
TypeRegistry.find_by_type_id(type_id)['name']
for type_id in compress(
range(Condition.MAX_SAFE_SUBTYPES),
map(lambda bit: int(bit), value['subtypes'])
)
}
condition._subtypes.update(subtypes)
return condition
def type_name(self):
return TypeRegistry.find_by_type_id(self.type_id)['name']
