diff --git a/Lib/ipaddress.py b/Lib/ipaddress.py --- a/Lib/ipaddress.py +++ b/Lib/ipaddress.py @@ -467,7 +467,8 @@ class _IPAddressBase(_TotalOrderingMixin raise AddressValueError(msg % (address, address_len, expected_len, self._version)) - def _ip_int_from_prefix(self, prefixlen): + @classmethod + def _ip_int_from_prefix(cls, prefixlen): """Turn the prefix length into a bitwise netmask Args: @@ -477,9 +478,10 @@ class _IPAddressBase(_TotalOrderingMixin An integer. """ - return self._ALL_ONES ^ (self._ALL_ONES >> prefixlen) - - def _prefix_from_ip_int(self, ip_int): + return cls._ALL_ONES ^ (cls._ALL_ONES >> prefixlen) + + @classmethod + def _prefix_from_ip_int(cls, ip_int): """Return prefix length from the bitwise netmask. Args: @@ -492,22 +494,24 @@ class _IPAddressBase(_TotalOrderingMixin ValueError: If the input intermingles zeroes & ones """ trailing_zeroes = _count_righthand_zero_bits(ip_int, - self._max_prefixlen) - prefixlen = self._max_prefixlen - trailing_zeroes + cls._max_prefixlen) + prefixlen = cls._max_prefixlen - trailing_zeroes leading_ones = ip_int >> trailing_zeroes all_ones = (1 << prefixlen) - 1 if leading_ones != all_ones: - byteslen = self._max_prefixlen // 8 + byteslen = cls._max_prefixlen // 8 details = ip_int.to_bytes(byteslen, 'big') msg = 'Netmask pattern %r mixes zeroes & ones' raise ValueError(msg % details) return prefixlen - def _report_invalid_netmask(self, netmask_str): + @classmethod + def _report_invalid_netmask(cls, netmask_str): msg = '%r is not a valid netmask' % netmask_str raise NetmaskValueError(msg) from None - def _prefix_from_prefix_string(self, prefixlen_str): + @classmethod + def _prefix_from_prefix_string(cls, prefixlen_str): """Return prefix length from a numeric string Args: @@ -522,16 +526,17 @@ class _IPAddressBase(_TotalOrderingMixin # int allows a leading +/- as well as surrounding whitespace, # so we ensure that isn't the case if not _BaseV4._DECIMAL_DIGITS.issuperset(prefixlen_str): - self._report_invalid_netmask(prefixlen_str) + cls._report_invalid_netmask(prefixlen_str) try: prefixlen = int(prefixlen_str) except ValueError: - self._report_invalid_netmask(prefixlen_str) - if not (0 <= prefixlen <= self._max_prefixlen): - self._report_invalid_netmask(prefixlen_str) + cls._report_invalid_netmask(prefixlen_str) + if not (0 <= prefixlen <= cls._max_prefixlen): + cls._report_invalid_netmask(prefixlen_str) return prefixlen - def _prefix_from_ip_string(self, ip_str): + @classmethod + def _prefix_from_ip_string(cls, ip_str): """Turn a netmask/hostmask string into a prefix length Args: @@ -545,24 +550,24 @@ class _IPAddressBase(_TotalOrderingMixin """ # Parse the netmask/hostmask like an IP address. try: - ip_int = self._ip_int_from_string(ip_str) + ip_int = cls._ip_int_from_string(ip_str) except AddressValueError: - self._report_invalid_netmask(ip_str) + cls._report_invalid_netmask(ip_str) # Try matching a netmask (this would be /1*0*/ as a bitwise regexp). # Note that the two ambiguous cases (all-ones and all-zeroes) are # treated as netmasks. try: - return self._prefix_from_ip_int(ip_int) + return cls._prefix_from_ip_int(ip_int) except ValueError: pass # Invert the bits, and try matching a /0+1+/ hostmask instead. - ip_int ^= self._ALL_ONES + ip_int ^= cls._ALL_ONES try: - return self._prefix_from_ip_int(ip_int) + return cls._prefix_from_ip_int(ip_int) except ValueError: - self._report_invalid_netmask(ip_str) + cls._report_invalid_netmask(ip_str) class _BaseAddress(_IPAddressBase): @@ -1100,14 +1105,43 @@ class _BaseV4: # the valid octets for host and netmasks. only useful for IPv4. _valid_mask_octets = frozenset((255, 254, 252, 248, 240, 224, 192, 128, 0)) + _max_prefixlen = IPV4LENGTH + # There are only a handful of valid v4 netmasks, so we cache them all + # when constructed (see _make_netmask()). + _netmask_cache = {} + def __init__(self, address): self._version = 4 - self._max_prefixlen = IPV4LENGTH def _explode_shorthand_ip_string(self): return str(self) - def _ip_int_from_string(self, ip_str): + @classmethod + def _make_netmask(cls, arg): + """Make a (netmask, prefix_len) tuple from the given argument. + + Argument can be: + - an integer (the prefix length) + - a string representing the prefix length (e.g. "24") + - a string representing the prefix netmask (e.g. "255.255.255.0") + """ + if arg not in cls._netmask_cache: + if isinstance(arg, int): + prefixlen = arg + else: + try: + # Check for a netmask in prefix length form + prefixlen = cls._prefix_from_prefix_string(arg) + except NetmaskValueError: + # Check for a netmask or hostmask in dotted-quad form. + # This may raise NetmaskValueError. + prefixlen = cls._prefix_from_ip_string(arg) + netmask = IPv4Address(cls._ip_int_from_prefix(prefixlen)) + cls._netmask_cache[arg] = netmask, prefixlen + return cls._netmask_cache[arg] + + @classmethod + def _ip_int_from_string(cls, ip_str): """Turn the given IP string into an integer for comparison. Args: @@ -1128,11 +1162,12 @@ class _BaseV4: raise AddressValueError("Expected 4 octets in %r" % ip_str) try: - return int.from_bytes(map(self._parse_octet, octets), 'big') + return int.from_bytes(map(cls._parse_octet, octets), 'big') except ValueError as exc: raise AddressValueError("%s in %r" % (exc, ip_str)) from None - def _parse_octet(self, octet_str): + @classmethod + def _parse_octet(cls, octet_str): """Convert a decimal octet into an integer. Args: @@ -1148,7 +1183,7 @@ class _BaseV4: if not octet_str: raise ValueError("Empty octet not permitted") # Whitelist the characters, since int() allows a lot of bizarre stuff. - if not self._DECIMAL_DIGITS.issuperset(octet_str): + if not cls._DECIMAL_DIGITS.issuperset(octet_str): msg = "Only decimal digits permitted in %r" raise ValueError(msg % octet_str) # We do the length check second, since the invalid character error @@ -1168,7 +1203,8 @@ class _BaseV4: raise ValueError("Octet %d (> 255) not permitted" % octet_int) return octet_int - def _string_from_ip_int(self, ip_int): + @classmethod + def _string_from_ip_int(cls, ip_int): """Turns a 32-bit integer into dotted decimal notation. Args: @@ -1507,16 +1543,14 @@ class IPv4Network(_BaseV4, _BaseNetwork) # Constructing from a packed address if isinstance(address, bytes): self.network_address = IPv4Address(address) - self._prefixlen = self._max_prefixlen - self.netmask = IPv4Address(self._ALL_ONES) + self.netmask, self._prefixlen = self._make_netmask(self._max_prefixlen) #fixme: address/network test here return # Efficient constructor from integer. if isinstance(address, int): self.network_address = IPv4Address(address) - self._prefixlen = self._max_prefixlen - self.netmask = IPv4Address(self._ALL_ONES) + self.netmask, self._prefixlen = self._make_netmask(self._max_prefixlen) #fixme: address/network test here. return @@ -1526,16 +1560,10 @@ class IPv4Network(_BaseV4, _BaseNetwork) self.network_address = IPv4Address(self._ip_int_from_string(addr[0])) if len(addr) == 2: - try: - # Check for a netmask in prefix length form - self._prefixlen = self._prefix_from_prefix_string(addr[1]) - except NetmaskValueError: - # Check for a netmask or hostmask in dotted-quad form. - # This may raise NetmaskValueError. - self._prefixlen = self._prefix_from_ip_string(addr[1]) + arg = addr[1] else: - self._prefixlen = self._max_prefixlen - self.netmask = IPv4Address(self._ip_int_from_prefix(self._prefixlen)) + arg = self._max_prefixlen + self.netmask, self._prefixlen = self._make_netmask(arg) if strict: if (IPv4Address(int(self.network_address) & int(self.netmask)) != @@ -1575,10 +1603,10 @@ class _BaseV6: _ALL_ONES = (2**IPV6LENGTH) - 1 _HEXTET_COUNT = 8 _HEX_DIGITS = frozenset('0123456789ABCDEFabcdef') + _max_prefixlen = IPV6LENGTH def __init__(self, address): self._version = 6 - self._max_prefixlen = IPV6LENGTH def _ip_int_from_string(self, ip_str): """Turn an IPv6 ip_str into an integer.