# Copyright (C) Dnspython Contributors, see LICENSE for text of ISC license

# Copyright (C) 2006-2017 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.
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# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL NOMINUM BE LIABLE FOR
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"""DNS Reverse Map Names."""

import binascii

import dns.name
import dns.ipv6
import dns.ipv4

from dns._compat import PY3

ipv4_reverse_domain = dns.name.from_text('in-addr.arpa.')
ipv6_reverse_domain = dns.name.from_text('ip6.arpa.')


def from_address(text):
    """Convert an IPv4 or IPv6 address in textual form into a Name object whose
    value is the reverse-map domain name of the address.

    *text*, a ``text``, is an IPv4 or IPv6 address in textual form
    (e.g. '127.0.0.1', '::1')

    Raises ``dns.exception.SyntaxError`` if the address is badly formed.

    Returns a ``dns.name.Name``.
    """

    try:
        v6 = dns.ipv6.inet_aton(text)
        if dns.ipv6.is_mapped(v6):
            if PY3:
                parts = ['%d' % byte for byte in v6[12:]]
            else:
                parts = ['%d' % ord(byte) for byte in v6[12:]]
            origin = ipv4_reverse_domain
        else:
            parts = [x for x in str(binascii.hexlify(v6).decode())]
            origin = ipv6_reverse_domain
    except Exception:
        parts = ['%d' %
                 byte for byte in bytearray(dns.ipv4.inet_aton(text))]
        origin = ipv4_reverse_domain
    parts.reverse()
    return dns.name.from_text('.'.join(parts), origin=origin)


def to_address(name):
    """Convert a reverse map domain name into textual address form.

    *name*, a ``dns.name.Name``, an IPv4 or IPv6 address in reverse-map name
    form.

    Raises ``dns.exception.SyntaxError`` if the name does not have a
    reverse-map form.

    Returns a ``text``.
    """

    if name.is_subdomain(ipv4_reverse_domain):
        name = name.relativize(ipv4_reverse_domain)
        labels = list(name.labels)
        labels.reverse()
        text = b'.'.join(labels)
        # run through inet_aton() to check syntax and make pretty.
        return dns.ipv4.inet_ntoa(dns.ipv4.inet_aton(text))
    elif name.is_subdomain(ipv6_reverse_domain):
        name = name.relativize(ipv6_reverse_domain)
        labels = list(name.labels)
        labels.reverse()
        parts = []
        i = 0
        l = len(labels)
        while i < l:
            parts.append(b''.join(labels[i:i + 4]))
            i += 4
        text = b':'.join(parts)
        # run through inet_aton() to check syntax and make pretty.
        return dns.ipv6.inet_ntoa(dns.ipv6.inet_aton(text))
    else:
        raise dns.exception.SyntaxError('unknown reverse-map address family')