From 77a341a458d604287f46180db1facbdb540cd139 Mon Sep 17 00:00:00 2001
From: Renato Botelho <garga@FreeBSD.org>
Date: Fri, 6 Dec 2013 11:39:29 -0200
Subject: [PATCH] Add a knob to prefer IPv4 over IPv6, it fixes #2833

---
 etc/inc/util.inc                          | 10 ++++++++++
 etc/rc.bootup                             |  3 +++
 usr/local/www/system_advanced_network.php | 20 ++++++++++++++++++++
 3 files changed, 33 insertions(+)

diff --git a/etc/inc/util.inc b/etc/inc/util.inc
index 6e91eb61ab..69fcbf527a 100644
--- a/etc/inc/util.inc
+++ b/etc/inc/util.inc
@@ -2064,4 +2064,14 @@ function get_current_theme() {
 	return $theme;
 }
 
+/* Define what is preferred, IPv4 or IPv6 */
+function prefer_ipv4_or_ipv6() {
+	global $config;
+
+	if (isset($config['system']['prefer_ipv4']))
+		mwexec("/etc/rc.d/ip6addrctl prefer_ipv4");
+	else
+		mwexec("/etc/rc.d/ip6addrctl prefer_ipv6");
+}
+
 ?>
diff --git a/etc/rc.bootup b/etc/rc.bootup
index 89a2be722a..f391a27d1c 100755
--- a/etc/rc.bootup
+++ b/etc/rc.bootup
@@ -409,6 +409,9 @@ upnp_start();
 /* If powerd is enabled, lets launch it */
 activate_powerd();
 
+/* Set preferred protocol */
+prefer_ipv4_or_ipv6();
+
 /* Remove the old shutdown binary if we kept it. */
 if (file_exists("/sbin/shutdown.old"))
 	@unlink("/sbin/shutdown.old");
diff --git a/usr/local/www/system_advanced_network.php b/usr/local/www/system_advanced_network.php
index 82b5661c04..28450ad699 100644
--- a/usr/local/www/system_advanced_network.php
+++ b/usr/local/www/system_advanced_network.php
@@ -51,6 +51,7 @@ require_once("shaper.inc");
 $pconfig['ipv6nat_enable'] = isset($config['diag']['ipv6nat']['enable']);
 $pconfig['ipv6nat_ipaddr'] = $config['diag']['ipv6nat']['ipaddr'];
 $pconfig['ipv6allow'] = isset($config['system']['ipv6allow']);
+$pconfig['prefer_ipv4'] = isset($config['system']['prefer_ipv4']);
 $pconfig['polling_enable'] = isset($config['system']['polling']);
 $pconfig['sharednet'] = $config['system']['sharednet'];
 $pconfig['disablechecksumoffloading'] = isset($config['system']['disablechecksumoffloading']);
@@ -88,6 +89,12 @@ if ($_POST) {
 			unset($config['system']['ipv6allow']);
 		}
 
+		if($_POST['prefer_ipv4'] == "yes") {
+			$config['system']['prefer_ipv4'] = true;
+		} else {
+			unset($config['system']['prefer_ipv4']);
+		}
+
 		if($_POST['sharednet'] == "yes") {
 			$config['system']['sharednet'] = true;
 			system_disable_arp_wrong_if();
@@ -136,6 +143,9 @@ if ($_POST) {
 		// Configure flowtable support from filter.inc
 		flowtable_configure();
 
+		// Set preferred protocol
+		prefer_ipv4_or_ipv6();
+
 		$retval = filter_configure();
 		if(stristr($retval, "error") <> true)
 			$savemsg = get_std_save_message(gettext($retval));
@@ -227,6 +237,16 @@ function enable_change(enable_over) {
 									<input name="ipv6nat_ipaddr" type="text" class="formfld unknown" id="ipv6nat_ipaddr" size="20" value="<?=htmlspecialchars($pconfig['ipv6nat_ipaddr']);?>" />
 								</td>
 							</tr>
+							<tr>
+								<td width="22%" valign="top" class="vncell"><?=gettext("Prefer IPv4 over IPv6"); ?></td>
+								<td width="78%" class="vtable">
+									<input name="prefer_ipv4" type="checkbox" id="prefer_ipv4" value="yes" <?php if ($pconfig['prefer_ipv4']) echo "checked=\"checked\""; ?> />
+									<strong><?=gettext("Prefer to use IPv4 even if IPv6 is available"); ?></strong><br/>
+									<?=gettext("By default, if a hostname resolves IPv6 and IPv4 addresses ".
+									"IPv6 will be used, if you check this option, IPv4 will be " .
+									"used instead of IPv6."); ?><br />
+								</td>
+							</tr>
 							<tr>
 								<td colspan="2" class="list" height="12">&nbsp;</td>
 							</tr>