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#!/usr/bin/env python
__metaclass__ = type
import subprocess
import sys
from script_commands import (
helps,
run_subcommand,
UserError,
)
def tc(command):
"""Run a tc command under sudo.
:param tc: The remainder of the command (leaving out tc).
"""
subprocess.call('sudo tc ' + command, shell=True)
@helps(delay='Length of delay in miliseconds (each way).',
port='Port to induce delay on.')
def start(delay=500, port=443):
"""Add artificial latency to the lo interface on the specified port."""
tc('qdisc add dev lo root handle 1: prio')
tc('qdisc add dev lo parent 1:3 handle 30: netem delay %dms' % delay)
tc('filter add dev lo protocol ip parent 1:0 prio 3 u32 match ip'
' dport %d 0xffff flowid 1:3' % port)
tc('filter add dev lo protocol ip parent 1:0 prio 3 u32 match ip'
' sport %d 0xffff flowid 1:3' % port)
def stop():
"""Remove latency from the lo."""
tc('qdisc del dev lo root')
subcommands = {
'start': start,
'stop': stop,
}
if __name__ == "__main__":
try:
run_subcommand(subcommands, sys.argv[1:])
except UserError as e:
sys.stderr.write(str(e)+'\n')
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