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network_utils.py
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# -*- coding: utf-8 -*-
# -------------------------------------------------------------
# Salt — Network execution module
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
# Project: Nasqueron
# License: BSD-2-Clause
# -------------------------------------------------------------
import ipaddress
import re
# -------------------------------------------------------------
# CIDR netmask and prefixes
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
def is_valid_netmask(netmask):
# "255.255.255.240" → "11111111111111111111111111110000"
bits = "".join([format(int(octet), "b") for octet in netmask.split(".")])
# A netmask is valid if the suite of bits:
# - starts by contiguous 1, e.g. here 1111111111111111111111111111
# - ends by contiguous 0, e.g. here 0000
#
# Also, as 0.0.0.0 is invalid, netmask must starts by 1.
return re.compile("^1+0*$").match(bits) is not None
def netmask_to_cidr_prefix(netmask):
"""
Convert a netmask like 255.255.255.240 into a CIDR prefix like 24.
This can be useful for RHEL network scripts requiring PREFIX information.
"""
if not is_valid_netmask(netmask):
raise ValueError("Netmask is invalid.")
# The CIDR prefix is the count of 1 bits in each octet.
# e.g. 255.255.255.240 can be split in octets [255, 255, 255, 240],
# then becomes ['0b11111111', '0b11111111', '0b11111111', '0b11110000'].
#
# There is 24 "1" in this expression, that's 24 is our CIDR prefix.
return sum([bin(int(octet)).count("1") for octet in netmask.split(".")])
# -------------------------------------------------------------
# IPv6 prefixes
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
def _ipv6_address_to_prefix(address, prefixlen):
return ipaddress.IPv6Network((address, prefixlen), strict=False)
def can_directly_be_discovered(gateway, address, prefixlen):
"""Determines if the gateway belong to the same prefix than the address,
and so can be directly be discovered in NDP."""
return _ipv6_address_to_prefix(gateway, prefixlen) == _ipv6_address_to_prefix(
address, prefixlen
)

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