import socket
import random
import os
import subprocess
import ipaddress

# Google subnets to route through the random IP
SUBNETS = [
        "2001:4860:4000::/36",
        "2404:6800:4000::/36",
        "2607:f8b0:4000::/36",
        "2800:3f0:4000::/36",
        "2a00:1450:4000::/36",
        "2c0f:fb50:4000::/36",
        ] 

TEST_IP_EXTERNAL = "2a0d:f302:111:38cc::1"  # A public IPv6 NOT in the subnet

# 1) Get the machine's current primary IPv6 address
def get_current_ipv6():
    s = socket.socket(socket.AF_INET6, socket.SOCK_DGRAM)
    s.connect((TEST_IP_EXTERNAL, 80))
    current_ip = s.getsockname()[0]
    return current_ip

# 2) Generate a random IP address within the /64 subnet of the current primary IPv6
def generate_random_ipv6(ipv6):
    # Parse the original IP address and network
    original = ipaddress.ip_interface(ipv6)

    # Generate a random interface identifier
    random_int = random.randint(1, 2**64 - 1)
    new_ip = ipaddress.IPv6Interface((int(original.network.network_address) | random_int, original.network.prefixlen))

    return str(new_ip.ip)

def main():
    current_ipv6 = get_current_ipv6()

    # Get network interface and gateway
    default_route = subprocess.check_output("ip -6 route show default", shell=True).decode('utf-8')

    iface = default_route.split("dev ")[1].split()[0]
    current_gateway = default_route.split("via ")[1].split()[0]

    random_ipv6 = generate_random_ipv6(current_ipv6)

    # 2.5) Remove any existing non-given IPv6 addresses from previous runs of the scripts
    prev_ips_raw_output = subprocess.check_output(f"ip -6 addr show {iface} scope global", shell=True).decode('utf-8')

    prev_ips = [line.strip().split(" ")[1].split("/")[0] for line in prev_ips_raw_output.split("\n") if "inet6" in line]
    for ip in prev_ips:
        if ip != current_ipv6:
            os.popen(f"sudo ip -6 addr del {ip} dev {iface}")

    # 3) Add new IP to the interface
    os.popen(f"sudo ip -6 addr add {random_ipv6} dev {iface}")

    # 4) Set up routes such that the random IP address is now used as the source address for requests to given IPv6 subnets
    for subnet in SUBNETS:
        os.popen(f"sudo ip -6 route add {subnet} from {random_ipv6} dev {iface} via {current_gateway}")

if __name__ == "__main__":
    main()