#!/bin/bash

# Docs: http://lartc.org/howto

# Tweakables
IFACE="ppp0"
VOIP_HOST="$(dig +short sip.internode.on.net)"

UPLINK_RATE=450

VOIP_RATE=70
HIGH_RATE=130
NORM_RATE=240
BULK_RATE=10


# Symbolic 'constants'
ROOT=1
LIMIT=1
VOIP_TRAFFIC=10
HIGH_TRAFFIC=20
NORM_TRAFFIC=30
BULK_TRAFFIC=40


# Print status of classes
if [ "$1" = "status" ]; then
    tc -s qdisc ls dev ${IFACE}
    tc -s class ls dev ${IFACE}
    exit
fi

set -x

# clean existing down- and uplink qdiscs, hide errors
tc qdisc del dev ${IFACE} root    2> /dev/null > /dev/null
tc qdisc del dev ${IFACE} ingress 2> /dev/null > /dev/null

if [ "$1" = "stop" ]; then
    exit
fi

cd /


########## uplink #############

# install root HTB, point default traffic to NORM_TRAFFIC
tc qdisc add dev ${IFACE} \
    root handle ${ROOT}:0 \
    htb default ${NORM_TRAFFIC}


# LIMIT class shapes everything at $UPLINK_RATE speed
# this prevents huge queues in the DSL modem which destroy latency
tc class add dev ${IFACE} \
    parent ${ROOT}:0 classid ${ROOT}:${LIMIT} \
    htb rate ${UPLINK_RATE}Kbit ceil ${UPLINK_RATE}Kbit


# VoIP traffic class gets guaranteed bandwidth
tc class add dev ${IFACE} \
    parent ${ROOT}:${LIMIT} classid ${ROOT}:${VOIP_TRAFFIC} \
    htb rate ${VOIP_RATE}Kbit ceil ${UPLINK_RATE}Kbit prio 0

# High priority traffic
tc class add dev ${IFACE} \
    parent ${ROOT}:${LIMIT} classid ${ROOT}:${HIGH_TRAFFIC} \
    htb rate ${HIGH_RATE}Kbit ceil ${UPLINK_RATE}Kbit prio 1

# Normal priority traffic
tc class add dev ${IFACE} \
    parent ${ROOT}:${LIMIT} classid ${ROOT}:${NORM_TRAFFIC} \
    htb rate ${NORM_RATE}Kbit ceil ${UPLINK_RATE}Kbit prio 2

# Bulk traffic gets little default allowance
tc class add dev ${IFACE} \
    parent ${ROOT}:${LIMIT} classid ${ROOT}:${BULK_TRAFFIC} \
    htb rate ${BULK_RATE}Kbit ceil ${UPLINK_RATE}Kbit prio 3


# Stochastic Fairness
tc qdisc add dev ${IFACE} \
    parent ${ROOT}:${HIGH_TRAFFIC} handle ${HIGH_TRAFFIC}:0 \
    sfq perturb 10
tc qdisc add dev ${IFACE} \
    parent ${ROOT}:${NORM_TRAFFIC} handle ${NORM_TRAFFIC}:0 \
    sfq perturb 10
tc qdisc add dev ${IFACE} \
    parent ${ROOT}:${BULK_TRAFFIC} handle ${BULK_TRAFFIC}:0 \
    sfq perturb 10


# Match VoIP traffic as highest priority
tc filter add dev ${IFACE} \
    parent ${ROOT}:0 protocol ip prio 10 u32 \
    match ip dst ${VOIP_HOST} flowid ${ROOT}:${VOIP_TRAFFIC}

# ICMP in the HIGH_TRAFFIC class
tc filter add dev ${IFACE} \
    parent ${ROOT}:0 protocol ip prio 10 u32 \
    match ip protocol 1 0xff flowid ${ROOT}:${HIGH_TRAFFIC}

# To speed up downloads while an upload is going on, ACK is HIGH_TRAFFIC
tc filter add dev ${IFACE} \
    parent ${ROOT}:0 protocol ip prio 10 u32 \
    match ip protocol 6 0xff \
    match u8 0x05 0x0f at 0 \
    match u16 0x0000 0xffc0 at 2 \
    match u8 0x10 0xff at 33 \
    flowid ${ROOT}:${HIGH_TRAFFIC}

# TOS Minimum-Delay (eg ssh but not scp) in HIGH_TRAFFIC
tc filter add dev ${IFACE} \
    parent ${ROOT}:0 protocol ip prio 10 u32 \
    match ip tos 0x10 0xff flowid ${ROOT}:${HIGH_TRAFFIC}

# TOS Maximise-Throughput (eg rtorrent) in BULK_TRAFFIC
tc filter add dev ${IFACE} \
    parent ${ROOT}:0 protocol ip prio 10 u32 \
    match ip tos 0x08 0xff flowid ${ROOT}:${BULK_TRAFFIC}