def cidr_to_ipv4_match()

in packages/aws-rfdk/lib/deadline/scripts/python/configure_identity_registration_settings.py [0:0]

• 18 lines of code
• 8 McCabe index (conditional complexity)

def cidr_to_ipv4_match(cidr: str) -> str:
    network = ipaddress.ip_network(cidr)
    if not isinstance(network, ipaddress.IPv4Network):
        raise TypeError(f'"{cidr}" is not an IPv4 network')

    # Get the network address, net mask, and host mask as byte arrays
    nw_address = network.network_address.packed
    netmask = network.netmask.packed
    hostmask = network.hostmask.packed

    ipv4_match_octets: List[str] = []


    for byte_netmask, byte_hostmask, byte_nw_address in zip(netmask, hostmask, nw_address):
        if byte_netmask == BYTE_MASK:
            # If all bits in the byte are part of the netmask, just set
            # the byte as defined in the network address
            ipv4_match_octets.append(str(byte_nw_address))
        elif byte_netmask == 0:
            # If none of the bits of the byte are part of the netmask, the
            # byte is free and we can match any IP
            ipv4_match_octets.append('*')
        else:
            # In this case, the byte is partially fixed and we need to find the
            # range
            byte_min = byte_netmask & byte_nw_address
            byte_max = byte_min + byte_hostmask
            ipv4_match_octets.append(f'{byte_min}-{byte_max}')

    return '.'.join(ipv4_match_octets)