#!/bin/bash
# Copyright (C) 2014 Nicira, Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at:
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

check_command_avail () {
    while [ $# -ne 0 ]; do
        if ("$1" --version) > /dev/null 2>&1; then :; else
            echo >&2 "$UTIL: missing $1, cannot proceed"
            exit 1
        fi
        shift
    done
}

ovs_vsctl () {
    ovs-vsctl --timeout=60 "$@"
}

create_netns_link () {
    mkdir -p /var/run/netns
    if [ ! -e /var/run/netns/"$PID" ]; then
        ln -s /proc/"$PID"/ns/net /var/run/netns/"$PID"
        trap 'delete_netns_link' 0
        for signal in 1 2 3 13 14 15; do
            trap 'delete_netns_link; trap - $signal; kill -$signal $$' $signal
        done
    fi
}

delete_netns_link () {
    rm -f /var/run/netns/"$PID"
}

add_port () {
    BRIDGE="$1"
    INTERFACE="$2"
    CONTAINER="$3"
    ADDRESS="$4"

    if [ "$#" -lt 3 ]; then
        usage
        exit 1
    fi

    if ovs_vsctl --may-exist add-br "$BRIDGE"; then :; else
        echo >&2 "$UTIL: Failed to create bridge $BRIDGE"
        exit 1
    fi

    if PID=`docker inspect -f '{{.State.Pid}}' "$CONTAINER"`; then :; else
        echo >&2 "$UTIL: Failed to get the PID of the container"
        exit 1
    fi

    create_netns_link

    # Create a veth pair.
    ID=`uuidgen | sed 's/-//g'`
    PORTNAME="${ID:0:13}"
    ip link add "${PORTNAME}_l" type veth peer name "${PORTNAME}_c"

    # Add one end of veth to OVS bridge.
    if ovs_vsctl --may-exist add-port "$BRIDGE" "${PORTNAME}_l" \
       -- set interface "${PORTNAME}_l" \
       external_ids:container_id="$CONTAINER" \
       external_ids:container_iface="$INTERFACE"; then :; else
        echo >&2 "$UTIL: Failed to add "${PORTNAME}_l" port to bridge $BRIDGE"
        ip link delete "${PORTNAME}_l"
        exit 1
    fi

    ip link set "${PORTNAME}_l" up

    # Move "${PORTNAME}_c" inside the container and changes its name.
    ip link set "${PORTNAME}_c" netns "$PID"
    ip netns exec "$PID" ip link set dev "${PORTNAME}_c" name "$INTERFACE"
    ip netns exec "$PID" ip link set "$INTERFACE" up

    if [ -n "$ADDRESS" ]; then
        ip netns exec "$PID" ip addr add "$ADDRESS" dev "$INTERFACE"
    fi
}

del_port () {
    BRIDGE="$1"
    INTERFACE="$2"
    CONTAINER="$3"

    if [ "$#" -lt 3 ]; then
        usage
        exit 1
    fi

    PORT=`ovs_vsctl --data=bare --no-heading --columns=name find interface \
             external_ids:container_id="$CONTAINER"  \
             external_ids:container_iface="$INTERFACE"`
    if [ -z "$PORT" ]; then
        echo >&2 "$UTIL: Failed to find any attached port in $BRIDGE" \
                 "for CONTAINER=$CONTAINER and INTERFACE=$INTERFACE"
        exit 1
    fi

    ovs_vsctl --if-exists del-port "$PORT"

    ip link delete "$PORT"
}

del_ports () {
    BRIDGE="$1"
    CONTAINER="$2"
    if [ "$#" -lt 2 ]; then
        usage
        exit 1
    fi

    PORTS=`ovs_vsctl --data=bare --no-heading --columns=name find interface \
             external_ids:container_id="$CONTAINER"`
    if [ -z "$PORTS" ]; then
        exit 0
    fi

    for PORT in $PORTS; do
        ovs_vsctl --if-exists del-port "$PORT"
        ip link delete "$PORT"
    done
}

usage() {
    cat << EOF
${UTIL}: Performs integration of Open vSwitch with Docker.
usage: ${UTIL} COMMAND

Commands:
  add-port BRIDGE INTERFACE CONTAINER [ADDRESS]
                    Adds INTERFACE inside CONTAINER and connects it as a port
                    in Open vSwitch BRIDGE. Optionally, sets ADDRESS on
                    INTERFACE. ADDRESS can include a '/' to represent network
                    prefix length. e.g.:
                    ${UTIL} add-port br-int eth1 c474a0e2830e 192.168.1.2/24
  del-port BRIDGE INTERFACE CONTAINER
                    Deletes INTERFACE inside CONTAINER and removes its
                    connection to Open vSwitch BRIDGE. e.g.:
                    ${UTIL} del-port br-int eth1 c474a0e2830e
  del-ports BRIDGE CONTAINER
                    Removes all Open vSwitch interfaces from CONTAINER. e.g.:
                    ${UTIL} del-ports br-int c474a0e2830e
Options:
  -h, --help        display this help message.
EOF
}

UTIL=$(basename $0)
check_command_avail ovs-vsctl docker uuidgen

if (ip netns) > /dev/null 2>&1; then :; else
    echo >&2 "$UTIL: ip utility not found (or it does not support netns),"\
             "cannot proceed"
    exit 1
fi

if [ $# -eq 0 ]; then
    usage
    exit 0
fi

case $1 in
    "add-port")
        shift
        add_port "$@"
        exit 0
        ;;
    "del-port")
        shift
        del_port "$@"
        exit 0
        ;;
    "del-ports")
        shift
        del_ports "$@"
        exit 0
        ;;
    -h | --help)
        usage
        exit 0
        ;;
    *)
        echo >&2 "$UTIL: unknown command \"$1\" (use --help for help)"
        exit 1
        ;;
esac