fix issue where clsact qdisc is applied twice resulting in failure

[liowsj]

• commands are now created then applied immediately, instead of creating all commands first then applying.
• avoids issue where commands are created by referring to an outdated system state where clsact qdisc has not been applied yet

[AzuraTarmiziIntel]

an example if using netlink courtesy of google.

code Example:
python
from pyroute2 import IPRoute
from pyroute2.netlink.exceptions import NetlinkError

def setup_clsact(ifname="eth0"):
with IPRoute() as ip:
idx = ip.link_lookup(ifname=ifname)[0]

    # Check if clsact already exists
    qdiscs = ip.get_qdiscs(idx)
    clsact_exists = any(q.get_attr('TCA_KIND') == 'clsact' for q in qdiscs)
    
    if not clsact_exists:
        print(f"Adding clsact to {ifname}...")
        try:
            ip.tc("add", "clsact", idx)
            print("clsact added successfully.")
        except NetlinkError as e:
            print(f"Failed to add clsact: {e}")
    else:
        print(f"clsact already exists on {ifname}.")

Run the check

setup_clsact("eth0") # Replace with your interface name

i like this netlink solution. we are moving away from filtering output from tc commands anyway in the future. so it makes this helper function future proof.
Code once code well. :)

[AzuraTarmiziIntel]

Explained.