--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/VirtualMailManager/network.py	Sat Mar 05 22:46:17 2011 +0000
@@ -0,0 +1,100 @@
+# -*- 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))