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Filename : rcode.py
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# 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 Result Codes."""

import dns.exception
from ._compat import long

#: No error
NOERROR = 0
#: Form error
FORMERR = 1
#: Server failure
SERVFAIL = 2
#: Name does not exist ("Name Error" in RFC 1025 terminology).
NXDOMAIN = 3
#: Not implemented
NOTIMP = 4
#: Refused
REFUSED = 5
#: Name exists.
YXDOMAIN = 6
#: RRset exists.
YXRRSET = 7
#: RRset does not exist.
NXRRSET = 8
#: Not authoritative.
NOTAUTH = 9
#: Name not in zone.
NOTZONE = 10
#: Bad EDNS version.
BADVERS = 16

_by_text = {
    'NOERROR': NOERROR,
    'FORMERR': FORMERR,
    'SERVFAIL': SERVFAIL,
    'NXDOMAIN': NXDOMAIN,
    'NOTIMP': NOTIMP,
    'REFUSED': REFUSED,
    'YXDOMAIN': YXDOMAIN,
    'YXRRSET': YXRRSET,
    'NXRRSET': NXRRSET,
    'NOTAUTH': NOTAUTH,
    'NOTZONE': NOTZONE,
    'BADVERS': BADVERS
}

# We construct the inverse mapping programmatically to ensure that we
# cannot make any mistakes (e.g. omissions, cut-and-paste errors) that
# would cause the mapping not to be a true inverse.

_by_value = {y: x for x, y in _by_text.items()}


class UnknownRcode(dns.exception.DNSException):
    """A DNS rcode is unknown."""


def from_text(text):
    """Convert text into an rcode.

    *text*, a ``text``, the textual rcode or an integer in textual form.

    Raises ``dns.rcode.UnknownRcode`` if the rcode mnemonic is unknown.

    Returns an ``int``.
    """

    if text.isdigit():
        v = int(text)
        if v >= 0 and v <= 4095:
            return v
    v = _by_text.get(text.upper())
    if v is None:
        raise UnknownRcode
    return v


def from_flags(flags, ednsflags):
    """Return the rcode value encoded by flags and ednsflags.

    *flags*, an ``int``, the DNS flags field.

    *ednsflags*, an ``int``, the EDNS flags field.

    Raises ``ValueError`` if rcode is < 0 or > 4095

    Returns an ``int``.
    """

    value = (flags & 0x000f) | ((ednsflags >> 20) & 0xff0)
    if value < 0 or value > 4095:
        raise ValueError('rcode must be >= 0 and <= 4095')
    return value


def to_flags(value):
    """Return a (flags, ednsflags) tuple which encodes the rcode.

    *value*, an ``int``, the rcode.

    Raises ``ValueError`` if rcode is < 0 or > 4095.

    Returns an ``(int, int)`` tuple.
    """

    if value < 0 or value > 4095:
        raise ValueError('rcode must be >= 0 and <= 4095')
    v = value & 0xf
    ev = long(value & 0xff0) << 20
    return (v, ev)


def to_text(value):
    """Convert rcode into text.

    *value*, and ``int``, the rcode.

    Raises ``ValueError`` if rcode is < 0 or > 4095.

    Returns a ``text``.
    """

    if value < 0 or value > 4095:
        raise ValueError('rcode must be >= 0 and <= 4095')
    text = _by_value.get(value)
    if text is None:
        text = str(value)
    return text