network traffic fuse

if_fuse.py

#! coding: UTF-8
#
# Example: if_fuse.py -i wwan0 -t 450M -c ip link set wwan0 down
#
import time
import pyroute2
import subprocess
import argparse
import atexit

def num_bytes(s):
	lv = 1024**("KMGT".find(s[-1].upper()) + 1)
	if lv != 1:
		return int(s[:-1])*lv
	return int(s)

p = argparse.ArgumentParser()
p.add_argument("-i", "--interface", dest="iface")
p.add_argument("-s", "--send", dest="send", type=num_bytes, default=-1)
p.add_argument("-r", "--recv", dest="recv", type=num_bytes, default=-1)
p.add_argument("-t", "--total", dest="total", type=num_bytes, default=-1)
p.add_argument("-c", "--cmd", dest="cmds", nargs="*", action="append")
opt = p.parse_args()

def diff64(prev, cur):
	ret = 0
	if cur < prev:
		ret = 0xffffffffffffffff
	return ret + cur - prev

prev = None
tx_bytes = 0
rx_bytes = 0
loop = True

def log_bytes():
	print "rx=%d tx=%d" % (rx_bytes, tx_bytes)

atexit.register(log_bytes)

ip=pyroute2.IPRoute()
while loop:
	if prev:
		time.sleep(1)
	for n in ip.link("dump"):
		if opt.iface and dict(n["attrs"])["IFLA_IFNAME"]!=opt.iface:
			continue
		
		s = dict(n["attrs"])["IFLA_STATS64"]
		if prev is None:
			prev = s
		else:
			tx_bytes += diff64(prev["tx_bytes"], s["tx_bytes"])
			rx_bytes += diff64(prev["rx_bytes"], s["rx_bytes"])
		
		if opt.recv!=-1 and opt.recv < rx_bytes:
			loop = False
		elif opt.send!=-1 and opt.send < tx_bytes:
			loop = False
		elif opt.total!=-1 and opt.total < rx_bytes+tx_bytes:
			loop = False

for cmd in opt.cmds:
	try:
		subprocess.call(cmd)
	except Exception:
		logging.error("cmd failed", exc_info=True)

if_fuse.service

[Unit]
Description=Interface fuse command
After=network.target

[Service]
ExecStart=/home/pi/if_fuse_py/bin/python /home/pi/if_fuse/if_fuse.py -i wwan0 -t 450M -c ip link set wwan0 down

[Install]
WantedBy=multi-user.target