# -*- coding: UTF-8 -*-

# Copyright (c) 2011 - 2012, Pascal Volk

# See COPYING for distribution information.

"""

    VirtualMailManager.network

    ~~~~~~~~~~~~~~~~~~~~~~~~~~

    Network/IP address related class and function

"""

import socket

from binascii import b2a_hex

class NetInfo(object):

    """Simple class for CIDR network addresses an IP addresses."""

    __slots__ = ('_addr', '_prefix', '_bits_max', '_family', '_nw_addr')

    def __init__(self, nw_address):

        """Creates a new `NetInfo` instance.

        Argument:

        `nw_address` : basestring

          string representation of an IPv4/IPv6 address or network address.

          E.g. 192.0.2.13, 192.0.2.0/24, 2001:db8::/32 or ::1

          When the address has no netmask the prefix length will be set to

          32 for IPv4 addresses and 128 for IPv6 addresses.

        """

        self._addr = None

        self._prefix = 0

        self._bits_max = 0

        self._family = 0

        self._nw_addr = nw_address

        self._parse_net_range()

    def __hash__(self):

        return hash((self._addr, self._family, self._prefix))

    def __repr__(self):

        return "NetInfo('%s')" % self._nw_addr

    def _parse_net_range(self):

        """Parse the network range of `self._nw_addr and assign values

        to the class attributes.

        `"""

        sep = '/'

        if self._nw_addr.count(sep):

            ip_address, sep, self._prefix = self._nw_addr.partition(sep)

            self._family, self._addr = get_ip_addr_info(ip_address)

        else:

            self._family, self._addr = get_ip_addr_info(self._nw_addr)

        self._bits_max = (128, 32)[self._family is socket.AF_INET]

        if self._prefix is 0:

            self._prefix = self._bits_max

        else:

            try:

                self._prefix = int(self._prefix)

            except ValueError:

                raise ValueError('Invalid prefix length: %r' % self._prefix)

        if self._prefix > self._bits_max or self._prefix < 0:

            raise ValueError('Invalid prefix length: %r' % self._prefix)

    @property

    def family(self):

        """Address family: `socket.AF_INET` or `socket.AF_INET6`"""

        return self._family

    def address_in_net(self, ip_address):

        """Checks if the `ip_address` belongs to the same subnet."""

        family, address = get_ip_addr_info(ip_address)

        if family != self._family:

            return False

        return address >> self._bits_max - self._prefix == \

               self._addr >> self._bits_max - self._prefix

def get_ip_addr_info(ip_address):

    """Checks if the string `ip_address` is a valid IPv4 or IPv6 address.

    When the `ip_address` could be validated successfully a tuple

    `(address_family, address_as_long)` will be returned. The

    `address_family`will be either `socket.AF_INET` or `socket.AF_INET6`.

    """

    if not isinstance(ip_address, str) or not ip_address:

        raise TypeError('ip_address must be a non empty string.')

    if not ip_address.count(':'):

        family = socket.AF_INET

        try:

            address = socket.inet_aton(ip_address)

        except socket.error:

            raise ValueError('Not a valid IPv4 address: %r' % ip_address)

    elif not socket.has_ipv6:

        raise ValueError('Unsupported IP address (IPv6): %r' % ip_address)

    else:

        family = socket.AF_INET6

        try:

            address = socket.inet_pton(family, ip_address)

        except socket.error:

            raise ValueError('Not a valid IPv6 address: %r' % ip_address)

    return (family, int(b2a_hex(address), 16))