Add a script to be used for updating systemd-resolved

contrib/ifup-systemd-resolved.sh

@@ -0,0 +1,119 @@
+#!/bin/bash
+
+# -------------------------------------------------------------------------------
+# LICENSE:
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+# -------------------------------------------------------------------------------
+
+# This is an `ifup` script to be used for integrating openfortivpn and
+# systemd-resolved. When the network interface goes up, the DNS server information
+# will be added to `systemd-resolved` without modifying /etc/resolve.conf.
+#
+# This script is largely based on the main script from the `update-systemd-resolved`
+# package, see: https://github.com/jonathanio/update-systemd-resolved
+
+DBUS_DEST="org.freedesktop.resolve1"
+DBUS_NODE="/org/freedesktop/resolve1"
+
+SCRIPT_NAME="${BASH_SOURCE[0]##*/}"
+
+log() {
+    logger -s -t "$SCRIPT_NAME" "$@"
+}
+
+for level in emerg err warning info debug; do
+    printf -v functext -- '%s() { log -p user.%s -- "$@" ; }' "$level" "$level"
+    eval "$functext"
+done
+
+get_link_info() {
+    dev="$1"
+    shift
+
+    link=''
+    link="$(ip link show dev "$dev")" || return $?
+
+    echo "$dev" "${link%%:*}"
+}
+
+busctl_call() {
+    # Preserve busctl's exit status
+    busctl call "$DBUS_DEST" "$DBUS_NODE" "${DBUS_DEST}.Manager" "$@" || {
+	local -i status=$?
+	    emerg "'busctl' exited with status $status"
+	    return $status
+	}
+}
+
+up() {
+    local link="$1"
+    shift
+    local if_index="$1"
+    shift
+
+    local -a dns_servers=() dns_domain=() dns_search=() dns_routed=()
+    local -i dns_server_count=0 dns_domain_count=0 dns_search_count=0 dns_routed_count=0
+    local dns_sec=""
+
+    for address in ${DNS_SERVERS}; do
+        (( dns_server_count += 1 ))
+        dns_servers+=(2 4 ${address//./ })
+    done
+
+    for domain in ${DNS_SUFFIX}; do
+	 (( dns_search_count += 1 ))
+	dns_search+=("${domain}" false)
+    done
+
+    if [[ "${#dns_servers[*]}" -gt 0 ]]; then
+	busctl_params=("$if_index" "$dns_server_count" "${dns_servers[@]}")
+	info "SetLinkDNS(${busctl_params[*]})"
+	busctl_call SetLinkDNS 'ia(iay)' "${busctl_params[@]}" || return $?
+    fi
+
+    if [[ "${#dns_domain[*]}" -gt 0 \
+	|| "${#dns_search[*]}" -gt 0 \
+	|| "${#dns_routed[*]}" -gt 0 ]]; then
+	    dns_count=$((dns_domain_count+dns_search_count+dns_routed_count))
+	    busctl_params=("$if_index" "$dns_count")
+	    if [[ "${#dns_domain[*]}" -gt 0 ]]; then
+		busctl_params+=("${dns_domain[@]}")
+	    fi
+	    if [[ "${#dns_search[*]}" -gt 0 ]]; then
+		busctl_params+=("${dns_search[@]}")
+	    fi
+	    if [[ "${#dns_routed[*]}" -gt 0 ]]; then
+		busctl_params+=("${dns_routed[@]}")
+	    fi
+	    info "SetLinkDomains(${busctl_params[*]})"
+	    busctl_call SetLinkDomains 'ia(sb)' "${busctl_params[@]}" || return $?
+    fi
+
+    if [[ -n "${dns_sec}" ]]; then
+	if [[ "${dns_sec}" == "default" ]]; then
+	    # We need to provide an empty string to use the default settings
+	    info "SetLinkDNSSEC($if_index '')"
+	    busctl_call SetLinkDNSSEC 'is' "$if_index" "" || return $?
+	else
+	    info "SetLinkDNSSEC($if_index ${dns_sec})"
+	    busctl_call SetLinkDNSSEC 'is' "$if_index" "${dns_sec}" || return $?
+	fi
+    fi
+}
+
+dev=${NET_DEVICE}
+read -r link if_index _ < <(get_link_info "$dev")
+up "$link" "$if_index"
+systemd-resolve --flush-caches