interfaces: add support for SLAAC WAN interfaces w/o DHCPv6 #5862; closes #5883

New script to be invoked by rtsold when Router Advertisements with
RDNSS / DNSSL information are received. Uses ifctl to create the
/tmp/$if_routerv6 file and creates the /tmp/$if_defaultgwv6 file
directly. Fixes the issue that these files don't get created when
the M and O flags in RAs are not set. Also, passes RDNSS / DNSSL
info from RAs to ifctl.

LICENSE

@@ -35,6 +35,7 @@ Copyright (c) 2015 Manuel Faux <mfaux@conf.at>
 Copyright (c) 2003-2006 Manuel Kasper <mk@neon1.net>
 Copyright (c) 2012 Marcello Coutinho
 Copyright (c) 2018 Martin Wasley <martin@team-rebellion.net>
+Copyright (c) 2022 Maurice Walker <maurice@walker.earth>
 Copyright (c) 2010-2015 Michael Bostock
 Copyright (c) 2019-2021 Michael Muenz <m.muenz@gmail.com>
 Copyright (c) 2019 Pascal Mathis <mail@pascalmathis.com>

plist

@@ -806,6 +806,7 @@
 /usr/local/opnsense/scripts/interfaces/ppp-linkup.sh
 /usr/local/opnsense/scripts/interfaces/ppp-uptime.sh
 /usr/local/opnsense/scripts/interfaces/reconfigure_vlans.php
+/usr/local/opnsense/scripts/interfaces/rtsold_resolvconf.sh
 /usr/local/opnsense/scripts/interfaces/traffic_stats.php
 /usr/local/opnsense/scripts/interfaces/traffic_top.py
 /usr/local/opnsense/scripts/ipsec/connect.py

src/etc/inc/interfaces.inc

@@ -2710,12 +2710,12 @@ function interface_dhcpv6_configure($interface, $wancfg)
     killbypid('/var/run/rtsold.pid', 'TERM', true);
 
     $rtsoldcommand = exec_safe(
-        '/usr/sbin/rtsold -p %s -M %s -O %s -R %s -a',
+        '/usr/sbin/rtsold -p %s -M %s -O %s -R %s -a -u',
         array(
             '/var/run/rtsold.pid',
             '/var/etc/rtsold_script.sh',
             '/var/etc/rtsold_script.sh',
-            '/usr/bin/true', /* XXX missing proper script to refresh resolv.conf */
+            '/usr/local/opnsense/scripts/interfaces/rtsold_resolvconf.sh',
         )
     );
 

src/opnsense/scripts/interfaces/rtsold_resolvconf.sh

@@ -0,0 +1,77 @@
+#!/bin/sh
+
+# Copyright (c) 2022 Maurice Walker <maurice@walker.earth>
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are met:
+#
+# 1. Redistributions of source code must retain the above copyright notice,
+#    this list of conditions and the following disclaimer.
+#
+# 2. Redistributions in binary form must reproduce the above copyright
+#    notice, this list of conditions and the following disclaimer in the
+#    documentation and/or other materials provided with the distribution.
+#
+# THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
+# INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
+# AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+# AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
+# OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+# POSSIBILITY OF SUCH DAMAGE.
+
+# This script is to be invoked by rtsold when a Router Advertisement
+# with RDNSS / DNSSL options is encountered. It extracts interface,
+# router and DNS information from arguments and STDIN.
+
+if [ -z "${2}" ]; then
+	echo "Nothing to do."
+	exit 0
+fi
+
+# ${2} is 'ifname:slaac:[RA-source-address]', where 'ifname' is the
+# interface the RA was received on.
+
+ifname=${2%%:*}
+rasrca=${2##*:slaac:[}
+rasrca=${rasrca%]}
+
+# XXX replace by exlusive 'ifname:slaac' use and falling back internally in ifctl?
+if [ -n "$(/usr/local/sbin/ifctl -i ${ifname} -6r)" ]; then
+	echo "IPv6 gateway for ${ifname} already exists."
+	exit 0
+fi
+
+# ${1} indicates whether DNS information should be added or deleted.
+
+if [ "${1}" = "-a" ]; then
+	/usr/local/sbin/ifctl -i ${ifname} -6rd -a ${rasrca}
+	# XXX stop modifying defaultgw files in scripts
+	echo ${rasrca} > /tmp/${ifname}_defaultgwv6
+
+	# rtsold sends a resolv.conf(5) file to STDIN of this script
+	while IFS=' ' read -r type value; do
+		if [ "${type}" = "nameserver" ]; then
+			# in:  nameserver 2001:db8::1
+			#      nameserver 2001:db8::2
+			#      nameserver 2001:db8::3
+			# out: -a 2001:db8::1 -a 2001:db8::2 -a 2001:db8::3
+			nameservers="${nameservers} -a ${value}"
+		elif [ "${type}" = "search" ]; then
+			# in:  search example.com example.net example.org
+			# out: -a example.com -a example.net -a example.org
+			for entry in $value; do
+				searchlist="${searchlist} -a ${entry}"
+			done
+		fi
+	done
+
+	/usr/local/sbin/ifctl -i ${ifname} -6nd ${nameservers}
+	/usr/local/sbin/ifctl -i ${ifname} -6sd ${searchlist}
+	/usr/local/sbin/configctl -d interface newipv6 ${ifname}
+fi
+
+# XXX implement -d as well