GUI 上で指定した Delay と Loss率 を使って、 tc qdisc による遅延・パケロスの設定の追加を行う、 Python コード

update_qdisc.py

#!/usr/bin/env python3
from typing import List
import tkinter as tk
import tkinter.messagebox as messagebox
import tkinter.ttk as ttk
import subprocess

ETH0 = 'eth0'
ETH1 = 'eth1'
TC_PATH = '/usr/sbin/tc'
COMBO_DELAY_LIST = ('0ms', '1ms', '2ms', '4ms', '7ms', '10ms', '20ms', '40ms', '70ms', '100ms', '200ms', '400ms', '700ms', '1000ms')
COMBO_LOSS_LIST = ('0%', '1%', '2%', '3%', '4%', '5%', '10%', '20%', '50%', '100%')

def run_exec(commands: List[str], *, encoding: str='utf-8'):
    result = subprocess.run(
        commands, stdout=subprocess.PIPE, stderr=subprocess.PIPE, check=True
    )
    return (result.stdout.decode(encoding), result.stderr.decode(encoding), result.returncode)

def has_netem(interface: str) -> bool:
    stdout, stderr, code = run_exec(f'sudo { TC_PATH } qdisc show dev { interface }'.split())
    if code != 0:
        raise Exception(f'Unexpcedted returncode: {code}\n' + stderr)
    return 'netem' in stdout

def set_netem(interface: str, delay: str, loss: str) -> None:
    cmd = 'change' if has_netem(interface) else 'add'
    _, stderr, code = run_exec(f'sudo { TC_PATH } qdisc { cmd } dev { interface } root netem delay { delay } loss { loss }'.split())
    if code != 0:
        raise Exception(f'Unexpcedted returncode: {code}\n' + stderr)

def reset_netem(interface: str) -> None:
    if has_netem(interface):
        _, stderr, code = run_exec(f'sudo { TC_PATH } qdisc del dev { interface } root netem'.split())
        if code != 0:
            raise Exception(f'Unexpcedted returncode: {code}\n' + stderr)

def main():
    root = tk.Tk()
    root.tk.call('tk', 'scaling', 1.5)

    # Delay
    tk.Label(root, text='Delay:').grid(column=0, row=0)
    v_delay = tk.StringVar()
    cmb_delay = ttk.Combobox(root, state='readonly', values=COMBO_DELAY_LIST, textvariable=v_delay)
    cmb_delay.current(0)
    cmb_delay.grid(column=1, row=0)

    # Loss
    tk.Label(root, text='Loss:').grid(column=0, row=1)
    v_loss = tk.StringVar()
    cmb_loss = ttk.Combobox(root, state='readonly', values=COMBO_LOSS_LIST, textvariable=v_loss)
    cmb_loss.current(0)
    cmb_loss.grid(column=1, row=1)

    btn_apply = tk.Button(root, text='Apply')
    btn_reset = tk.Button(root, text='Reset')

    def on_clicked_apply():
        btn_apply['state'] = tk.DISABLED
        try:
            delay = v_delay.get()
            loss = v_loss.get()
            set_netem(interface=ETH0, delay=delay, loss=loss)
            set_netem(interface=ETH1, delay=delay, loss=loss)
        finally:
            btn_apply['state'] = tk.NORMAL

    def on_clicked_reset():
        btn_reset['state'] = tk.DISABLED
        try:
            reset_netem(interface=ETH0)
            reset_netem(interface=ETH1)
        finally:
            btn_reset['state'] = tk.NORMAL

    btn_apply['command'] = on_clicked_apply
    btn_apply.grid(row=2, columnspan=2)
    btn_reset['command'] = on_clicked_reset
    btn_reset.grid(row=3, columnspan=2)

    root.mainloop()

    reset_netem(interface=ETH0)
    reset_netem(interface=ETH1)

if __name__ == "__main__":
    main()