# Copyright (C) Dnspython Contributors, see LICENSE for text of ISC license
import binascii
import struct
import dns.immutable
import dns.rdata
import dns.rdatatype
import dns.zonetypes
@dns.immutable.immutable
class ZONEMD(dns.rdata.Rdata):
"""ZONEMD record"""
# See RFC 8976
__slots__ = ["serial", "scheme", "hash_algorithm", "digest"]
def __init__(self, rdclass, rdtype, serial, scheme, hash_algorithm, digest):
super().__init__(rdclass, rdtype)
self.serial = self._as_uint32(serial)
self.scheme = dns.zonetypes.DigestScheme.make(scheme)
self.hash_algorithm = dns.zonetypes.DigestHashAlgorithm.make(hash_algorithm)
self.digest = self._as_bytes(digest)
if self.scheme == 0: # reserved, RFC 8976 Sec. 5.2
raise ValueError("scheme 0 is reserved")
if self.hash_algorithm == 0: # reserved, RFC 8976 Sec. 5.3
raise ValueError("hash_algorithm 0 is reserved")
hasher = dns.zonetypes._digest_hashers.get(self.hash_algorithm)
if hasher and hasher().digest_size != len(self.digest):
raise ValueError("digest length inconsistent with hash algorithm")
def to_text(self, origin=None, relativize=True, **kw):
kw = kw.copy()
chunksize = kw.pop("chunksize", 128)
return "%d %d %d %s" % (
self.serial,
self.scheme,
self.hash_algorithm,
dns.rdata._hexify(self.digest, chunksize=chunksize, **kw),
)
@classmethod
def from_text(
cls, rdclass, rdtype, tok, origin=None, relativize=True, relativize_to=None
):
serial = tok.get_uint32()
scheme = tok.get_uint8()
hash_algorithm = tok.get_uint8()
digest = tok.concatenate_remaining_identifiers().encode()
digest = binascii.unhexlify(digest)
return cls(rdclass, rdtype, serial, scheme, hash_algorithm, digest)
def _to_wire(self, file, compress=None, origin=None, canonicalize=False):
header = struct.pack("!IBB", self.serial, self.scheme, self.hash_algorithm)
file.write(header)
file.write(self.digest)
@classmethod
def from_wire_parser(cls, rdclass, rdtype, parser, origin=None):
header = parser.get_struct("!IBB")
digest = parser.get_remaining()
return cls(rdclass, rdtype, header[0], header[1], header[2], digest)
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