#!/bin/sh
#TOPRATE=872kbit
#echo "Don't run this script now."
#exit 1

TOPRATE=10Mbit
case ${MODE:-$1} in
 start)
   echo Starting traffic control for ${IFACE:=$2}
   # Top-level queue for interface; hierarchical token bucket.
   # TBF doesn't support classes, so I can't put a full qdisc in it.
   tc qdisc add dev $IFACE root handle 1: htb default 10
   # Root rate queue. This one defines our output capacity.
   tc class add dev $IFACE parent 1: classid 1:1 htb rate $TOPRATE
   # Default rate queue
   tc class add dev $IFACE parent 1:1 classid 1:10 htb rate 3Mbit ceil $TOPRATE burst 15k prio 2
   # High-priority rate queue
   tc class add dev $IFACE parent 1:1 classid 1:20 htb rate 7Mbit ceil $TOPRATE burst 15k prio 1
   # Stochastic fairness queuing, limited by above rates.
   tc qdisc add dev $IFACE parent 1:10 handle 10: sfq perturb 10
   tc qdisc add dev $IFACE parent 1:20 handle 20: sfq perturb 10
   # Filters to sort out high-priority packets
   ## match acks the hard way,
   ## IP protocol 6,
   ## IP header length 0x5(32 bit words),
   ## IP Total length 0x34 (ACK + 12 bytes of TCP options)
   ## TCP ack set (bit 5, offset 33)
   #tc filter add dev $IFACE parent 1: protocol ip 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

   # ICMP or UDP traffic
   #tc filter add dev $IFACE parent 1: protocol ip u32 \
   #    match ip protocol 1 0xef flowid 1:20

   # Let iptables mark the packets for high priority.
   tc filter add dev $IFACE parent 1: protocol ip handle 1 fw classid 1:20
   ;;
 stop)
   echo Stopping traffic control for ${IFACE:=$2}
   tc qdisc del dev $IFACE root
   ;;
 *)
   echo Usage: $0 {start,stop} interface
   ;;
esac