+week = 7*day
+
+REGEX_label = r'[a-zA-Z90-9]([a-zA-Z90-9-]{0,61}[a-zA-Z90-9])?' # max. 63 characters; must not start or end with hyphen
+
+def check_label(label: str) -> str:
+ pattern = r'^{0}$'.format(REGEX_label)
+ if re.match(pattern, label):
+ return label
+ raise Exception(label+" is not a valid label")
+
+def check_hostname(name: str) -> str:
+ # check hostname for validity
+ pattern = r'^{0}(\.{0})*\.?$'.format(REGEX_label)
+ if re.match(pattern, name):
+ return name
+ raise Exception(name+" is not a valid hostname")
+
+def check_hex(data: str) -> str:
+ if re.match('^[a-fA-F0-9]+$', data):
+ return data
+ raise Exception(data+" is not valid hex data")
+
+def time(time: int) -> str:
+ if time == 0:
+ return "0"
+ elif time % week == 0:
+ return str(time//week)+"w"
+ elif time % day == 0:
+ return str(time//day)+"d"
+ elif time % hour == 0:
+ return str(time//hour)+"h"
+ elif time % minute == 0:
+ return str(time//minute)+"m"
+ else:
+ return str(time)
+
+def column_widths(datas: Sequence, widths: Sequence[int]):
+ assert len(datas) == len(widths)+1, "There must be as one more data points as widths"
+ result = ""
+ width_sum = 0
+ for data, width in zip(datas, widths): # will *not* cover the last point
+ result += str(data)+" " # add data point, and a minimal space
+ width_sum += width
+ if len(result) < width_sum: # add padding
+ result += (width_sum - len(result))*" "
+ # last data point
+ return result+str(datas[-1])
+
+
+## Enums
+class Protocol:
+ TCP = 'tcp'
+ UDP = 'udp'
+
+class Algorithm:
+ RSA_SHA256 = 8
+
+class Digest:
+ SHA1 = 1
+ SHA256 = 2
+
+
+## Record types
+class A:
+ def __init__(self, address: str) -> None:
+ self._address = IPv4Address(address)
+
+ def generate_rr(self, owner: str, zone: 'Zone') -> Any:
+ return zone.RR(owner, 'A', self._address)
+
+
+class AAAA:
+ def __init__(self, address: str) -> None:
+ self._address = IPv6Address(address)
+
+ def generate_rr(self, owner: str, zone: 'Zone') -> Any:
+ return zone.RR(owner, 'AAAA', self._address)
+
+
+class MX:
+ def __init__(self, name: str, prio: int = 10) -> None:
+ self._priority = int(prio)
+ self._name = check_hostname(name)
+
+ def generate_rr(self, owner: str, zone: 'Zone') -> Any:
+ return zone.RR(owner, 'MX', '{0} {1}'.format(self._priority, zone.abs_hostname(self._name)))
+
+
+class SRV:
+ def __init__(self, protocol: str, service: str, name: str, port: int, prio: int, weight: int) -> None:
+ self._service = check_label(service)
+ self._protocol = check_label(protocol)
+ self._priority = int(prio)
+ self._weight = int(weight)
+ self._port = int(port)
+ self._name = check_hostname(name)
+
+ def generate_rr(self, owner: str, zone: 'Zone') -> Any:
+ return zone.RR('_{0}._{1}.{2}'.format(self._service, self._protocol, owner), 'SRV',
+ '{0} {1} {2} {3}'.format(self._priority, self._weight, self._port, zone.abs_hostname(self._name)))
+
+
+class TLSA:
+ class Usage:
+ CA = 0 # certificate must pass the usual CA check, with the CA specified by the TLSA record
+ EndEntity_PlusCAs = 1 # the certificate must match the TLSA record *and* pass the usual CA check
+ TrustAnchor = 2 # the certificate must pass a check with the TLSA record giving the (only) trust anchor
+ EndEntity = 3 # the certificate must match the TLSA record
+
+ class Selector:
+ Full = 0
+ SubjectPublicKeyInfo = 1
+
+ class MatchingType:
+ Exact = 0
+ SHA256 = 1
+ SHA512 = 2
+
+ def __init__(self, protocol: str, port: int, usage: int, selector: int, matching_type: int, data: str) -> None:
+ self._port = int(port)
+ self._protocol = str(protocol)
+ self._usage = int(usage)
+ self._selector = int(selector)
+ self._matching_type = int(matching_type)
+ self._data = check_hex(data)
+
+ def generate_rr(self, owner: str, zone: 'Zone') -> Any:
+ return zone.RR('_{0}._{1}.{2}'.format(self._port, self._protocol, owner), 'TLSA', '{0} {1} {2} {3}'.format(self._usage, self._selector, self._matching_type, self._data))
+
+
+class CNAME:
+ def __init__(self, name: str) -> None:
+ self._name = check_hostname(name)
+
+ def generate_rr(self, owner: str, zone: 'Zone') -> Any:
+ return zone.RR(owner, 'CNAME', zone.abs_hostname(self._name))
+