#!/bin/sh
#
# Script fragment to make ifupdown supply DNS infromation to resolved
#

case "$ADDRFAM" in
    inet|inet6) : ;;
    *) exit 0 ;;
esac            

if systemctl is-enabled systemd-resolved > /dev/null 2>&1; then
    mystatedir statedir ifindex interface

    interface=$IFACE
    if [ ! "$interface" ]; then
        return
    fi
    # TODO handle lo interface settings
    if [ "$interface" = "lo" ]; then
        return
    fi
    ifindex=$(cat "/sys/class/net/$interface/ifindex")
    if [ ! "$ifindex" ]; then
        return
    fi
    mystatedir=/run/network
    mkdir -p $mystatedir

    statedir=/run/systemd/resolve/netif
    mkdir -p $statedir
    chown systemd-resolve:systemd-resolve $statedir

    oldstate="$(mktemp)"
    # ignore errors due to nonexistent file
    md5sum "$mystatedir/isc-dhcp-v4-$interface" "$mystatedir/isc-dhcp-v6-$interface" "$mystatedir/ifupdown-inet-$interface" "$mystatedir/ifupdown-inet6-$interface" > "$oldstate" 2> /dev/null || true

    NEW_DEFAULT_ROUTE=$IF_DNS_DEFAULT_ROUTE
    NEW_DNS=$(echo $IF_DNS_NAMESERVERS $IF_DNS_NAMESERVER)
    NEW_DOMAINS=$(echo $IF_DNS_DOMAIN $IF_DNS_SEARCH)
    DNS=DNS
    DOMAINS=DOMAINS
    if [ "$ADDRFAM" = "inet6" ]; then
        DNS=DNS6
        DOMAINS=DOMAINS6
    fi
    if  [ -n "$NEW_DNS" ]; then
        cat <<EOF >"$mystatedir/ifupdown-${ADDRFAM}-$interface"
$DNS="$NEW_DNS"
EOF
        if  [ -n "$NEW_DOMAINS" ]; then
            cat <<EOF >>"$mystatedir/ifupdown-${ADDRFAM}-$interface"
$DOMAINS="$NEW_DOMAINS"
EOF
        fi
    fi
    case "$NEW_DEFAULT_ROUTE" in
        1|yes|true|on) NEW_DEFAULT_ROUTE=yes ;;
        0|no|false|off) NEW_DEFAULT_ROUTE=no ;;
        *) NEW_DEFAULT_ROUTE= ;;
    esac
    if [ -n "$NEW_DEFAULT_ROUTE" ]; then
        cat <<EOF >>"$mystatedir/ifupdown-${ADDRFAM}-$interface"
DEFAULT_ROUTE="$NEW_DEFAULT_ROUTE"
EOF
    fi

    newstate="$(mktemp)"
    # ignore errors due to nonexistent file
    md5sum "$mystatedir/isc-dhcp-v4-$interface" "$mystatedir/isc-dhcp-v6-$interface" "$mystatedir/ifupdown-inet-$interface" "$mystatedir/ifupdown-inet6-$interface" > "$newstate" 2> /dev/null || true
    if ! cmp --silent "$oldstate" "$newstate" 2>/dev/null; then
        DNS DNS6 DOMAINS DOMAINS6 DEFAULT_ROUTE
        # v4 first
        if [ -e "$mystatedir/isc-dhcp-v4-$interface" ]; then
            . "$mystatedir/isc-dhcp-v4-$interface"
        fi
        # v4 manual config overrides
        if [ -e "$mystatedir/ifupdown-inet-$interface" ]; then
            . "$mystatedir/ifupdown-inet-$interface"
        fi
        # v6 preffered
        if [ -e "$mystatedir/isc-dhcp-v6-$interface" ]; then
            . "$mystatedir/isc-dhcp-v6-$interface"
        fi
        # v6 manual config overrides
        if [ -e "$mystatedir/ifupdown-inet6-$interface" ]; then
            . "$mystatedir/ifupdown-inet6-$interface"
        fi
        resolvectl_failed=
        if [ "$DNS" ] || [ "$DNS6" ] ; then
            cat <<EOF >"$statedir/$ifindex"
# This is private data. Do not parse.
LLMNR=yes
MDNS=no
SERVERS=$(echo $DNS6 $DNS)
DOMAINS=$(echo $DOMAINS6 $DOMAINS)
EOF
            if [ -n "$DEFAULT_ROUTE" ]; then
                cat <<EOF >>"$statedir/$ifindex"
DEFAULT_ROUTE=$DEFAULT_ROUTE
EOF
            fi
            chown systemd-resolve:systemd-resolve "$statedir/$ifindex"
            # In addition to creating the state file (needed if we run before
            # resolved is started), also feed the information directly to
            # resolved.
            if systemctl --quiet is-active systemd-resolved; then
                resolvectl llmnr "$ifindex" yes || resolvectl_failed=$?
                resolvectl mdns "$ifindex" no || resolvectl_failed=$?
                if [ "$DOMAINS6" ] || [ "$DOMAINS" ]; then
                    resolvectl domain "$ifindex" $DOMAINS6 $DOMAINS || resolvectl_failed=$?
                else
                    resolvectl domain "$ifindex" "" || resolvectl_failed=$?
                fi
                resolvectl dns "$ifindex" $DNS6 $DNS || resolvectl_failed=$?
                if [ "$DEFAULT_ROUTE" ]; then
                    resolvectl default-route "$ifindex" $DEFAULT_ROUTE || resolvectl_failed=$?
                fi
            fi
        else
            rm -f "$statedir/$ifindex"
            if systemctl --quiet is-active systemd-resolved; then
                resolvectl revert "$ifindex" || resolvectl_failed=$?
            fi
        fi

        # resolved was running, but without dbus, it means state files
        # will not be read & resolvectl commands failed, restart it
        if [ "$resolvectl_failed" ]; then
                systemctl try-restart systemd-resolved
        fi
    fi
    rm -f "$oldstate" "$newstate"
fi