#!/bin/bash
set -e

# You may need to adjust
#    echo 4096 >/proc/sys/net/ipv4/neigh/default/gc_thresh3
# where the number is greater than NUM_WEAVES*(NUM_WEAVES-1) plus some
# fudge.
#
# Without that, some connections between the weaves may fail to get
# established, and networking on the host in general becomes
# broken. There will also be some "net_ratelimit: nnn callbacks
# suppressed" messages in the syslog.

START=${FIRST_WEAVE:-1}
COUNT=${NUM_WEAVES:-28}
FINISH=$((START+COUNT-1))

SUBNET=192.168.7

weavedir=$(dirname $0)/..

# Generate a random MAC value - copied from 'weave' script
random_mac() {
    # In the first byte of the MAC, the 'multicast' bit should be
    # clear and 'locally administered' bit should be set.  All other
    # bits should be random.
    od -txC -An -N6 /dev/urandom | ( read a b c d e f && printf "%02x:$b:$c:$d:$e:$f" $((0x$a & ~1 | 2)) )
}

weave() {
    i=$1
    shift
    WEAVE_CONTAINER_NAME=weave$i WEAVE_HTTP_ADDR=$SUBNET.$i:6784 $weavedir/weave "$@"
}

case "$1" in
    launch)
        shift 1
        echo $(date -R) launching
        ip link show multiweave >/dev/null 2>&1 || sudo ip link add name multiweave type bridge
        for i in $(seq $START $FINISH); do
            IP=$SUBNET.$i
            sudo ip addr add $IP/24 dev multiweave
            weave $i launch --datapath '' --iface '' --no-dns --host $IP \
                --name $(random_mac) --nickname weave$i "$@"
        done
        echo $(date -R) connecting
        [ $START -gt 1 ] || START=2
        for i in $(seq $START $FINISH); do
            TO=$SUBNET.$((i-1))
            echo connecting weave$i to $TO
            weave $i connect $TO
        done
        echo $(date -R) done
        ;;
    stop)
        for i in $(seq $FINISH -1 $START); do
            IP=$SUBNET.$i
            echo Stopping weave$i
            weave $i stop
            sudo ip addr del $IP/24 dev multiweave || true
        done
        [ -z "$(ip -4 -o addr show multiweave)" ] && sudo ip link del multiweave
        ;;
    *)
            weave "$@"
        ;;
esac