terom@740: import ipaddress
tero@456: import math
tero@456: 
tero@456: def reverse_ipv4 (ip) :
tero@456:     """
tero@456:         Return in-addr.arpa reverse for given IPv4 prefix.
tero@456:     """
tero@456: 
tero@456:     # parse
tero@456:     octets = tuple(int(part) for part in ip.split('.'))
tero@456: 
tero@456:     for octet in octets :
tero@456:         assert 0 <= octet <= 255
tero@456: 
tero@456:     return '.'.join([str(octet) for octet in reversed(octets)] + ['in-addr', 'arpa'])
tero@456: 
tero@456: def reverse_ipv6 (ip6) :
tero@456:     """
tero@456:         Return ip6.arpa reverse for given IPv6 prefix.
tero@456:     """
tero@456: 
tero@456:     # XXX: this is broken for fd80::1?
tero@456:     parts = [int(part, 16) for part in ip6.split(':')]
tero@456:     parts = ['{0:04x}'.format(part) for part in parts]
tero@456:     parts = ''.join(parts)
tero@456: 
tero@456:     return '.'.join(tuple(reversed(parts)) + ( 'ip6', 'arpa'))
tero@456: 
tero@456: def reverse_label (prefix, address) :
tero@456:     """
tero@456:         Determine the correct label for the given IP address within the reverse zone for the given prefix.
tero@456: 
tero@456:         This includes all suffix octets (partially) covered by the prefix.
tero@456:     """
tero@456: 
tero@456:     assert prefix.version == address.version
tero@456:     assert address in prefix
tero@456:     
tero@456:     hostbits = prefix.max_prefixlen - prefix.prefixlen
tero@456: 
tero@456:     if prefix.version == 4 :
tero@456:         # pack into octets
tero@456:         octets = [ord(x) for x in address.packed]
tero@456: 
tero@456:         # take the suffix
tero@456:         octets = octets[-int(math.ceil(hostbits / 8.0)):]
tero@456:         
tero@456:         # reverse in decimal
tero@456:         return '.'.join(reversed(["{0:d}".format(x) for x in octets]))
tero@456: 
tero@456:     elif prefix.version == 6 :
tero@456:         # pack into nibbles
tero@456:         nibbles = [((ord(x) >> 4) & 0xf, ord(x) & 0xf) for x in address.packed]
tero@456:         nibbles = [nibble for nibblepair in nibbles for nibble in nibblepair]
tero@456: 
tero@456:         # take the suffix
tero@456:         nibbles = nibbles[-(hostbits / 4):]
tero@456:         
terom@740:         # reveurse in hex
tero@456:         return '.'.join(reversed(["{0:x}".format(x) for x in nibbles]))
tero@456: 
tero@456:     else :
tero@456:         raise ValueError("unsupported address version: %s" % (prefix, ))
tero@456: 
tero@456: def _split_ipv6_parts (prefix) :
tero@456:     """
tero@456:         Split a partial IPv6 address into hexadecimal nibbles
tero@456:     """
tero@456: 
tero@456:     if prefix.endswith('::'):
tero@456:         prefix = prefix[:-2]
tero@456: 
tero@456:     for hextet in prefix.split(':') :
tero@456:         for nibble in hextet.rjust(4, '0') :
tero@456:             yield nibble
tero@456: 
tero@456: def _build_ipv6_parts (parts) :
tero@456:     """
tero@456:         Group an iterable of hexadecimal nibbles into hextets.
tero@456:     """
tero@456: 
tero@456:     for i in xrange(0, len(parts), 4) :
terom@740:         yield u''.join(parts[i:i+4])
tero@456:     
tero@456:     # suffix ::
tero@456:     if len(parts) < 32 :
terom@740:         yield u''
terom@740:         yield u''
tero@456: 
tero@456: def parse_prefix (prefix) :
tero@456:     """
terom@740:         Return an ipaddress.IPNetwork from given filesystem-compatbile IPv4/IPv6 prefix-ish variant.
tero@499: 
tero@499:         Supports partial IPv4 prefixes on octet boundaries.
tero@499:         Supports partial IPv6 prefixes on nibble boundaries.
tero@499:         Supports IPv4 prefxies using "-" as the prefix separator in place of "/".
tero@456: 
terom@740:         >>> print parse_prefix('127.0.0.0/8')
terom@740:         127.0.0.0/8
terom@740:         >>> print parse_prefix('192.0.2.128/26')
terom@740:         192.0.2.128/26
terom@740:         >>> print parse_prefix('192.0.2.128-26')
terom@740:         192.0.2.128/26
terom@740:         >>> print parse_prefix('127.')
terom@740:         127.0.0.0/8
terom@740:         >>> print parse_prefix('10')
terom@740:         10.0.0.0/8
terom@740:         >>> print parse_prefix('192.168')
terom@740:         192.168.0.0/16
terom@740:         >>> print parse_prefix('fe80::')
terom@740:         fe80::/16
terom@740:         >>> print parse_prefix('2001:db8::')
terom@740:         2001:db8::/32
terom@740:         >>> print parse_prefix('2001:db8:1:2')
terom@740:         2001:db8:1:2::/64
tero@456:     """
tero@456: 
terom@740:     prefix = unicode(prefix)
terom@740: 
tero@456:     if '/' in prefix :
terom@740:         return ipaddress.ip_network(prefix)
tero@456:     
tero@456:     elif '-' in prefix :
terom@740:         return ipaddress.ip_network(prefix.replace('-', '/'))
tero@456: 
tero@456:     elif '.' in prefix or prefix.isdigit() :
tero@456:         parts = prefix.rstrip('.').split('.')
tero@456:         prefixlen = len(parts) * 8
tero@456:         
terom@740:         return ipaddress.IPv4Network(u'{prefix}/{prefixlen}'.format(
terom@740:             prefix      = u'.'.join(parts + [u'0' for i in xrange(4 - len(parts))]),
tero@456:             prefixlen   = prefixlen,
tero@456:         ))
tero@456:    
tero@456:     elif ':' in prefix :
tero@456:         parts = list(_split_ipv6_parts(prefix))
tero@456:         prefixlen = len(parts) * 4
tero@456: 
terom@740:         return ipaddress.IPv6Network(u'{prefix}/{prefixlen}'.format(
terom@740:             prefix      = u':'.join(_build_ipv6_parts(parts)),
tero@456:             prefixlen   = prefixlen,
tero@456:         ))
tero@456: 
tero@456:     else :
tero@456:         raise ValueError("Unrecognized IP prefix string: %s" % (prefix, ))
tero@456: