#!/bin/sh
# vim: set ts=4 et:

set -e

PROC="$(basename "$0")[$$]"

DEBUG=

log() {
    [ -z "$DEBUG" ] && [ "$1" = "debug" ] && return
    local facility="kern.$1"
    shift
    logger -p "$facility" -t "$PROC" "$@"
}

if [ -z "$MDEV" ]; then
    log err "MDEV env not defined"
    exit 1
fi

# where's the tiny-cloud lib directory?
if [ -z "$TINY_CLOUD_LIBS" ]; then
	TINY_CLOUD_CONF=${TINY_CLOUD_CONF:-/etc/conf.d/tiny-cloud}
	[ -f "$TINY_CLOUD_CONF" ] && source "$TINY_CLOUD_CONF"
	TINY_CLOUD_LIBS=${TINY_CLOUD_LIBS:-/lib/tiny-cloud}
fi

IFACE_CFG=/etc/network/interfaces

ip() {
    local v=-4 lev=info
    if [ "$1" = '-4' ] || [ "$1" = '-6' ]; then
        v="$1"
        shift
    fi
    local op="$2"

    [ "$op" = show ] && lev=debug
    if /sbin/ip "$v" "$@" || [ -n "$FAIL_OK" ]; then
        log "$lev" "OK: ip $v $*"
    else
        log err "FAIL: ip $v $*"
    fi
}

assemble_interfaces() {
    log info "Rebuilding $IFACE_CFG"
    # TODO: might be elsewhere, source /etc/conf.d/tiny-cloud
    "$TINY_CLOUD_LIBS"/network-interfaces
}

interface_up() {
    log info "Bringing up $MDEV"
    # so /run/udhcpcd.$MDEV.pid isn't non-owner writeable
    (umask 0022 && ifup "$MDEV")
}

cleanup_interface() {
    local v p rtable="${MDEV#eth}"
    let rtable+=1000

    log info "Cleaning up $MDEV"

    # kill related udhcpc, don't panic if it's not there
    kill "$(cat "/run/udhcpc.$MDEV.pid")" || true

    # tidy up /run/ifstate, if it exists
    [ -f /run/ifstate ] && sed -i -e "/^$MDEV=/d" /run/ifstate
    rm -f /run/ifstate."$MDEV".lock

    # remove related rules
    for v in 4 6; do
        for p in $(ip -"$v" rule show table "$rtable" | cut -d: -f1); do
            ip -"$v" rule del pref "$p"
        done
    done
}

is_networking_started() { service networking status -q 2>/dev/null; }

log info "STARTING: $ACTION $MDEV"

if exec 200>>"$IFACE_CFG"; then
    if flock 200; then
        case $ACTION in
            add|"")
                assemble_interfaces
                is_networking_started && interface_up
                ;;
            remove)
                assemble_interfaces
                is_networking_started && cleanup_interface
                ;;
            *)
                log err "Unknown action '$ACTION'"
                exit 1
                ;;
        esac
    else
        log err "Unable to flock $IFACE_CFG"
        exit 1
    fi
else
    log err "Unable to assign fd 200 to flock $IFACE_CFG"
    exit 1
fi

log info "FINISHED: $ACTION $MDEV"