From c586bdb1a5f3252d4fb7cbbeb6b18a9617db62f3 Mon Sep 17 00:00:00 2001
From: Franco Fichtner <franco@opnsense.org>
Date: Wed, 24 May 2023 09:29:10 +0200
Subject: [PATCH] system: allow "." DNS search domain override; closes #6529

While here refactor get_searchdomain() a little to avoid complexity
in system_resolvconf_generate().
---
 src/etc/inc/system.inc     | 30 +++++++++++++++++++-----------
 src/www/system_general.php |  2 +-
 2 files changed, 20 insertions(+), 12 deletions(-)

diff --git a/src/etc/inc/system.inc b/src/etc/inc/system.inc
index 1c18eab33..5f743d2f2 100644
--- a/src/etc/inc/system.inc
+++ b/src/etc/inc/system.inc
@@ -184,8 +184,8 @@ function system_resolvconf_generate($verbose = false)
 
     $syscfg = config_read_array('system');
     $resolvconf = '';
-    $search = [];
     $routes = [];
+    $search = [];
 
     mwexecf(
         '/etc/rc.d/ip6addrctl %s',
@@ -194,25 +194,20 @@ function system_resolvconf_generate($verbose = false)
 
     if (!empty($syscfg['domain'])) {
         $resolvconf = "domain {$syscfg['domain']}\n";
-        $search[] = $syscfg['domain'];
-    }
-
-    if (!empty($syscfg['dnssearchdomain'])) {
-        /* add custom search entries after default domain before potential provider entries */
-        $search[] = $syscfg['dnssearchdomain'];
     }
 
     if (!isset($syscfg['dnslocalhost']) && !empty(service_by_filter(['dns_ports' => '53']))) {
         $resolvconf .= "nameserver 127.0.0.1\n";
     }
 
-    $search = array_merge($search, get_searchdomains());
     $routes = system_resolvconf_host_routes();
 
     foreach (array_keys($routes) as $host) {
         $resolvconf .= "nameserver {$host}\n";
     }
 
+    $search = get_searchdomains();
+
     if (count($search)) {
         $result = $search[0];
         /* resolv.conf search keyword limit is 6 domains, 256 characters */
@@ -237,10 +232,9 @@ function system_resolvconf_generate($verbose = false)
 
     /* setup static routes for DNS servers as configured */
     foreach ($routes as $host => $gateway) {
-        if (empty($gateway)) {
-            continue;
+        if (!empty($gateway)) {
+            system_host_route($host, $gateway);
         }
-        system_host_route($host, $gateway);
     }
 
     service_log("done.\n", $verbose);
@@ -306,6 +300,20 @@ function get_searchdomains()
     $master_list = [];
     $search_list = [];
 
+    if (!empty($syscfg['domain'])) {
+        $master_list[] = $syscfg['domain'];
+    }
+
+    if (!empty($syscfg['dnssearchdomain'])) {
+        if ($syscfg['dnssearchdomain'] == '.') {
+            /* pass root only */
+            return [$syscfg['dnssearchdomain']];
+       }
+
+        /* add custom search entries after default domain before potential provider entries */
+        $master_list[] = $syscfg['dnssearchdomain'];
+    }
+
     if (isset($syscfg['dnsallowoverride'])) {
         /* return domains as required by configuration */
         $list = shell_safe('/usr/local/sbin/ifctl -sl');
diff --git a/src/www/system_general.php b/src/www/system_general.php
index cda98d79e..f123d9d22 100644
--- a/src/www/system_general.php
+++ b/src/www/system_general.php
@@ -454,7 +454,7 @@ $( document ).ready(function() {
               <td>
                 <input name="dnssearchdomain" type="text" value="<?= $pconfig['dnssearchdomain'] ?>" />
                 <div class="hidden" data-for="help_for_dnssearchdomain">
-                  <?= gettext('Enter an additional domain to add to the local list of search domains.') ?>
+                  <?= gettext('Enter an additional domain to add to the local list of search domains. Use "." to disable passing any search domain for resolving.') ?>
                 </div>
               </td>
             </tr>