#!/usr/bin/env bash
set -e

BRIDGE=$1
GUEST_ID=$2
IPADDR=$3
BROADCAST=$4
GWADDR=$5
MAC=$6
GUESTNAME=$7
VLANTAG=$8

[ "$IPADDR" ] || {
    echo "Syntax:"
    echo "pipework <bridge> <guest-id> <ipaddr>/<subnet> <broadcast> <gateway> <mac> <guestname> [vlan tag]"
    exit 1
}

# Step 1: Find the guest (for now, we only support LXC containers)
while read dev mnt fstype options dump fsck
do
    [ "$fstype" != "cgroup" ] && continue
    echo $options | grep -qw devices || continue
    CGROUPMNT=$mnt
done < /proc/mounts

[ "$CGROUPMNT" ] || {
    echo "Could not locate cgroup mount point."
    exit 1
}

N=$(find "$CGROUPMNT" -name "$GUEST_ID*" | wc -l)
case "$N" in
    0)
    echo "Could not find any container matching $GUEST_ID"
    exit 1
    ;;
    1)
    true
    ;;
    *)
    echo "Found more than one container matching $GUEST_ID"
    exit 1
    ;;
esac

NSPID=$(head -n 1 $(find "$CGROUPMNT" -name "$GUEST_ID*" | head -n 1)/tasks)
[ "$NSPID" ] || {
    echo "Could not find a process inside container $GUEST_ID"
    exit 1
}

# Step 2: Prepare the working directory
sudo mkdir -p /var/run/netns
sudo rm -f /var/run/netns/$NSPID
sudo ln -s /proc/$NSPID/ns/net /var/run/netns/$NSPID

# Step 3: Creating virtual interfaces
LOCAL_IFNAME=vethl-$GUESTNAME #$NSPID
GUEST_IFNAME=vethg-$GUESTNAME #$NSPID
sudo ip link add name $LOCAL_IFNAME type veth peer name $GUEST_IFNAME
sudo ip link set $LOCAL_IFNAME up

# Step 4: Adding the virtual interface to the bridge
sudo ip link set $GUEST_IFNAME netns $NSPID
if [ "$VLANTAG" ]
then
    sudo ovs-vsctl add-port $BRIDGE $LOCAL_IFNAME tag=$VLANTAG
    echo $LOCAL_IFNAME
else
    sudo ovs-vsctl add-port $BRIDGE $LOCAL_IFNAME
    echo $LOCAL_IFNAME
fi

# Step 5: Configure networking within the container
sudo ip netns exec $NSPID ip link set $GUEST_IFNAME name eth0
sudo ip netns exec $NSPID ip addr add $IPADDR broadcast $BROADCAST dev eth0
sudo ip netns exec $NSPID ifconfig eth0 hw ether $MAC
sudo ip netns exec $NSPID ip addr add 127.0.0.1 dev lo
sudo ip netns exec $NSPID ip link set eth0 up
sudo ip netns exec $NSPID ip link set lo up
sudo ip netns exec $NSPID ip route add default via $GWADDR