VirtualMailManager/network.py
author martin f. krafft <madduck@madduck.net>
Sat, 07 Apr 2012 00:45:57 +0200
branchv0.6.x
changeset 492 e5c2b3647971
parent 421 ff2a61e155db
child 568 14abdd04ddf5
permissions -rw-r--r--
Modify address check query to obtain well-defined result The way in which UNION does not yield the desired result, because (a) UNION merges results and (b) the result order is undefined. This patch changes the query to select the counts as columns and hence provides a well-defined order.

# -*- coding: UTF-8 -*-
# Copyright (c) 2011, Pascal Volk
# See COPYING for distribution information.
"""
    VirtualMailManager.network
    ~~~~~~~~~~~~~~~~~~~~~~~~~~

    Network/IP address related class and function
"""

import socket


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, basestring) 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, long(address.encode('hex'), 16))