# Copyright (C) Dnspython Contributors, see LICENSE for text of ISC license
# Copyright (C) 2001-2017 Nominum, Inc.
#
# Permission to use, copy, modify, and distribute this software and its
# documentation for any purpose with or without fee is hereby granted,
# provided that the above copyright notice and this permission notice
# appear in all copies.
#
# THE SOFTWARE IS PROVIDED "AS IS" AND NOMINUM DISCLAIMS ALL WARRANTIES
# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL NOMINUM BE LIABLE FOR
# ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
# WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
# ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
# OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
"""DNS Message Flags."""
import enum
from typing import Any
# Standard DNS flags
class Flag(enum.IntFlag):
#: Query Response
QR = 0x8000
#: Authoritative Answer
AA = 0x0400
#: Truncated Response
TC = 0x0200
#: Recursion Desired
RD = 0x0100
#: Recursion Available
RA = 0x0080
#: Authentic Data
AD = 0x0020
#: Checking Disabled
CD = 0x0010
# EDNS flags
class EDNSFlag(enum.IntFlag):
#: DNSSEC answer OK
DO = 0x8000
#: Compact nonexistence, restore NXDOMAIN requested
CO = 0x4000
# Flags Mask (excludes opcode and rcode)
FLAGS_MASK = 0x87F0
# EDNS Flags Mask (excludes extended rcode and version)
EDNS_FLAGS_MASK = 0x0000FFFF
def _from_text(text: str, enum_class: Any) -> int:
flags = 0
tokens = text.split()
for t in tokens:
token = t.upper()
if token.startswith("FLAG") and token[4:].isdecimal():
# An unnamed flag, rendered by _to_text() as FLAGn (see below).
flags |= 1 << int(token[4:])
else:
flags |= enum_class[token]
return flags
def _to_text(flags: int, enum_class: Any) -> str:
text_flags = []
known = 0
for k, v in enum_class.__members__.items():
known |= int(v)
if flags & v != 0:
text_flags.append(k)
# Render any set bits that do not have a named flag as FLAGn, where n is
# the bit position, so that they are not silently dropped. These tokens
# round-trip through _from_text().
unknown = flags & ~known
bit = 0
while unknown:
if unknown & 1:
text_flags.append(f"FLAG{bit}")
unknown >>= 1
bit += 1
return " ".join(text_flags)
[docs]
def from_text(text: str) -> int:
"""Convert a space-separated list of flag text values into a flags
value.
:rtype: int
"""
return _from_text(text, Flag)
[docs]
def to_text(flags: int) -> str:
"""Convert a flags value into a space-separated list of flag text
values.
:rtype: str
"""
# We & with 0xff0 to mask out rcode.
return _to_text(flags & FLAGS_MASK, Flag)
[docs]
def edns_from_text(text: str) -> int:
"""Convert a space-separated list of EDNS flag text values into a EDNS
flags value.
:rtype: int
"""
return _from_text(text, EDNSFlag)
[docs]
def edns_to_text(flags: int) -> str:
"""Convert an EDNS flags value into a space-separated list of EDNS flag
text values.
:rtype: str
"""
return _to_text(flags & EDNS_FLAGS_MASK, EDNSFlag)
### BEGIN generated Flag constants
QR = Flag.QR
AA = Flag.AA
TC = Flag.TC
RD = Flag.RD
RA = Flag.RA
AD = Flag.AD
CD = Flag.CD
### END generated Flag constants
### BEGIN generated EDNSFlag constants
DO = EDNSFlag.DO
CO = EDNSFlag.CO
### END generated EDNSFlag constants