#!/bin/bash
# Copyright 2021 Google LLC
#
# 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.

source "$(dirname "${BASH_SOURCE[0]}")"/ncsid_lib.sh

NCSI_IF="$1"

old_rtr=
old_mac=

function set_rtr() {
    [ -n "$rtr" -a -n "$lifetime" ] || return
    [ "$rtr" != "$old_rtr" -a "$mac" != "$old_mac" ] || return
    # Only valid default routers can be considered, 0 lifetime implies
    # a non-default router
    (( lifetime > 0 )) || return

    echo "Setting default router: $rtr at $mac" >&2
    local svc=xyz.openbmc_project.Network
    SetStatic "$svc" "$NCSI_IF" || return
    UpdateGateway "$svc" "$NCSI_IF" "$rtr" || return
    UpdateNeighbor "$svc" "$NCSI_IF" "$rtr" "$mac" || return

    retries=-1
    old_mac="$mac"
    old_rtr="$rtr"
}

retries=1
w=60
while true; do
    start=$SECONDS
    args=(-m "$NCSI_IF" -w $(( w * 1000 )))
    if (( retries > 0 )); then
        args+=(-r "$retries")
    else
        args+=(-d)
    fi
    while read line; do
        if [ -z "$line" ]; then
            lifetime=
            mac=
        elif [[ "$line" =~ ^Router' 'lifetime' '*:' '*([0-9]*) ]]; then
            lifetime="${BASH_REMATCH[1]}"
        elif [[ "$line" =~ ^Source' 'link-layer' 'address' '*:' '*([a-fA-F0-9:]*)$ ]]; then
            mac="${BASH_REMATCH[1]}"
        elif [[ "$line" =~ ^from' '(.*)$ ]]; then
            rtr="${BASH_REMATCH[1]}"
            set_rtr || true
            lifetime=
            mac=
            rtr=
        fi
    done < <(exec rdisc6 "${args[@]}" 2>/dev/null)
    # If rdisc6 exits early we still want to wait the full `w` time before
    # starting again.
    (( timeout = start + w - SECONDS ))
    sleep $(( timeout < 0 ? 0 : timeout ))
done