#!/bin/bash -e

# Copyright © Vernon Mauery 2007-2009. All Rights Reserved.
# Author: Vernon Mauery <vernon [aT] mauery (dot) com>

# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
# 
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
# 
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA


# user settings
RATE_UP=1850
RATE_DOWN=4750
VOIP_RATE=90
VOIP_IP=69.59.224.0/19
VPN_IP=204.146.0.0/16
WAN_IF=ppp0

#
# End Configuration Options
#

LOCK_FILE=/var/run/qos_started

stop_shaper() {
    DEV=$1

    # Reset everything to a known state (cleared)
    tc qdisc del dev $DEV root >& /dev/null || :
    tc qdisc del dev $DEV ingress >& /dev/null || :
    echo "Shaping removed on $DEV"
}

start_shaper() {
    DEV=$1
    RATE_DOWN=$2
    RATE_UP=$3

    # Remove all qdiscs from the device to reset
    tc qdisc del dev $DEV root >& /dev/null || :
    tc qdisc del dev $DEV ingress >& /dev/null || :

    # set queue size to give latency of about 2 seconds on low-prio packets
    ip link set dev $DEV qlen 30

    #############################
    # egress (outbound traffic) #
    #############################

    # create root HTB qdisc, and point unclassified traffic to 1:40
    tc qdisc add dev $DEV root handle 1: htb default 40

    # shape all traffic with a rate limit of $RATE_UP which should
    # prevent queueing at the ISP, allowing us to control the queue length
    # and priority of packets that get sent
    tc class add dev $DEV parent 1: classid 1:1 htb \
        rate ${RATE_UP}kbit burst 6k

    # VoIP class (we want guaranteed priority on this one)
    tc class add dev $DEV parent 1:1 classid 1:10 htb \
        rate ${VOIP_RATE}kbit prio 0

    # high prio class 1:20 for low-latency packets
    tc class add dev $DEV parent 1:1 classid 1:20 htb \
        rate $[($RATE_UP-$VOIP_RATE)/4]kbit \
        ceil ${RATE_UP}kbit burst 6k prio 1

    # medium priority class 1:30 for small packets and the like
    tc class add dev $DEV parent 1:1 classid 1:30 htb \
        rate $[($RATE_UP-$VOIP_RATE)/4]kbit \
        ceil ${RATE_UP}kbit burst 6k prio 2

    # bulk prio class 1:40
    tc class add dev $DEV parent 1:1 classid 1:40 htb \
        rate $[($RATE_UP-$VOIP_RATE)/2]kbit \
        ceil ${RATE_UP}kbit prio 3

    # SFQ is mostly to make multiple streams share the bandwidth, so in the
    # case of our VoIP class, it is really only one stream and pfifo_fast
    # would be a better choice.  Not many packets should end up in the high
    # prio class (1:20), so we just let them go in fifo order as well.
    # But the two lowest prio classes (which likely have more traffic)
    # will likely benefit from SFQ.
    tc qdisc add dev $DEV parent 1:30 handle 30: sfq perturb 10
    tc qdisc add dev $DEV parent 1:40 handle 40: sfq perturb 10

    # filter VoIP stuff
    tc filter add dev $DEV parent 1:0 protocol ip prio 50 u32 \
        match ip protocol 17 0xff \
        match ip dst $VOIP_IP \
        flowid 1:10

    # TOS Minimum Delay (ssh, NOT scp) in 1:20:
    tc filter add dev $DEV parent 1:0 protocol ip prio 20 u32 \
        match ip tos 0x10 0xff flowid 1:20

    # ICMP (ip protocol 1) in the interactive class 1:10 so we 
    # can do measurements & impress our friends:
    tc filter add dev $DEV parent 1:0 protocol ip prio 20 u32 \
        match ip protocol 1 0xff flowid 1:20

    # To speed up downloads while an upload is going on, put ACK packets in
    # the interactive class:

    tc filter add dev $DEV parent 1: protocol ip prio 20 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 1:20

    # put the vpn in 1:30 so it doesn't get hurt by downloads
    tc filter add dev $DEV parent 1:0 protocol ip prio 10 u32 \
        match ip protocol 6 0xff \
        match ip dst $VPN_IP \
        match ip dport 443 0xffff \
        flowid 1:30

    # all other outbound traffic that doesn't match one of these
    # filters gets put in the default class, 1:40


    #############################
    # ingress (inbound traffic) #
    #############################

    # It is not possible to *shape* inbound traffic (I don't understand
    # reasoning behind this), but we are able to limit it.  The ingress
    # qdisc does not have classes or anything fancy, but we can add
    # filters to implement policing.  This means we can drop inbound
    # packets which will effectively limit our download speeds, which
    # makes it so our packets are not getting hung up in the HUGE
    # queues at the ISP.

    # I also tried to make sure that we didn't drop any VoIP packets
    # in the policing effort.  You might think of this as profiling. :)

    tc qdisc add dev $DEV handle ffff: ingress

    # filter VoIP traffic and enqueue it
    tc filter add dev $DEV parent ffff: protocol ip prio 50 u32 \
        match ip src $VOIP_IP \
        flowid :1

    # filter *everything* to it (0.0.0.0/0), drop everything that's
    # coming in too fast:
    tc filter add dev $DEV parent ffff: protocol ip prio 20 u32 \
        match ip src 0.0.0.0/0 \
        police rate $[($RATE_DOWN-$VOIP_RATE)]kbit burst 10k drop \
        flowid :1

    echo "Added shaping for $DEV limited at $RATE_DOWN/$RATE_UP kb/s"
}

start_qos() {
    [ -e $LOCK_FILE ] && return 1
    start_shaper "$WAN_IF" "$RATE_DOWN" "$RATE_UP"
    touch $LOCK_FILE
}

stop_qos() {
    stop_shaper "$WAN_IF"
    rm -f $LOCK_FILE >& /dev/null
}

qos_status() {
    echo "[qdisc]"
    tc -s qdisc show dev $WAN_IF
    echo "[class]"
    tc -s class show dev $WAN_IF
    echo "[filter]"
    tc -s filter show dev $WAN_IF
}

case $1 in
    start)
        start_qos
        ;;

    stop)
        stop_qos
        ;;

    restart)
        stop_qos
        start_qos
        ;;
    
    status)
        qos_status
        ;;

    *)
        echo "usage: $0 {start|stop|restart|status}"
        exit 1
        ;;
esac

exit 0