dhcp option 121 hex format convertor

convertor.py

import ipaddress

def hex_to_cidr(hex_str):
    i = 0
    while i < len(hex_str):
        # The first byte is the mask
        mask = int(hex_str[i:i+2], 16)
        i += 2

        # Calculate how many bytes the subnet will occupy
        subnet_bytes = -(-mask // 8)
        subnet = '.'.join(str(int(hex_str[i+j*2:i+(j+1)*2], 16)) for j in range(subnet_bytes))
        subnet += ''.join('.0' for _ in range(4-subnet_bytes))
        i += subnet_bytes * 2

        # The next four bytes are the router
        router = '.'.join(str(int(hex_str[i+j*2:i+(j+1)*2], 16)) for j in range(4))
        i += 8

        print(f'{subnet}/{mask}\t{router}')

hex_to_cidr('0FC612C0A801FD175B69C0C0A801FD165B6C04C0A801FD155B6C08C0A801FD155B6C10C0A801FD165B6C38C0A801FD145FA140C0A801FD14959AA0C0A801FD18B94C97C0A801FD')


def cidr_to_hex(cidrs):
    hex_str = ''
    for cidr, router in cidrs:
        # The first byte is the mask
        mask = int(cidr.split('/')[1])
        hex_str += '{:02X}'.format(mask)

        # The next bytes are the subnet
        subnet = cidr.split('/')[0]
        subnet_bytes = [int(part) for part in subnet.split('.')]
        for i in range(-(-mask // 8)):
            hex_str += '{:02X}'.format(subnet_bytes[i])

        # The next four bytes are the router
        router_bytes = [int(part) for part in router.split('.')]
        for byte in router_bytes:
            hex_str += '{:02X}'.format(byte)

    return hex_str

print(cidr_to_hex([
('198.18.0.0/15', ' 192.168.1.253'),
('192.168.93.0/24', ' 192.168.1.253'),
('91.105.192.0/23', ' 192.168.1.253'),
('91.108.4.0/22', ' 192.168.1.253'),
('91.108.8.0/21', ' 192.168.1.253'),
('91.108.16.0/21', ' 192.168.1.253'),
('91.108.56.0/22', ' 192.168.1.253'),
('95.161.64.0/20', ' 192.168.1.253'),
('149.154.160.0/20', ' 192.168.1.253'),
('185.76.151.0/24', ' 192.168.1.253'),
]))