system: improve debugging capability of dns static routes

We are progressing steadly here, but now we need more visibility
of the sources of DNS routes to summarize servers and sources.

Also try not to deduplicate routes prematurely so that dynamic
hosts get priority over config-based ones like the override
setting actually implies as currently the last one won.

src/etc/inc/system.inc

@@ -201,9 +201,15 @@ function system_resolvconf_generate($verbose = false)
     $search = array_merge($search, get_searchdomains());
 
     foreach (get_nameservers(null, true) as $dnsserver) {
+        if (isset($routes[$dnsserver['host']])) {
+            log_error("Duplicated DNS route ignored for {$dnsserver['host']} on {$dnsserver['interface']}");
+            continue;
+        }
+
         $host = !empty($dnsserver['host']) ? $dnsserver['host'] : $dnsserver;
         $resolvconf .= "nameserver {$host}\n";
-        $routes[] = $dnsserver;
+
+        $routes[$dnsserver['host']] = $dnsserver['gateway'];
     }
 
     if (count($search)) {
@@ -229,8 +235,8 @@ function system_resolvconf_generate($verbose = false)
     rename($tempfile, '/etc/resolv.conf');
 
     /* setup static routes for DNS servers as configured */
-    foreach ($routes as $route) {
-        system_host_route($route['host'], $route['gateway']);
+    foreach ($routes as $host => $gateway) {
+        system_host_route($host, $gateway);
     }
 
     if ($verbose) {
@@ -392,7 +398,12 @@ function get_nameservers($interface = null, $with_gateway = false)
             }
 
             if ($with_gateway) {
-                $master_list[] = ['host' => $dns, 'gateway' => $gw];
+                $master_list[] = [
+                    'host' => $dns,
+                    'gateway' => $gw,
+                    'interface' => convert_real_interface_to_friendly_interface_name($intf[0]),
+                    'source' => 'interface',
+                ];
             } else {
                 $master_list[] = $dns;
             }
@@ -431,15 +442,22 @@ function get_nameservers($interface = null, $with_gateway = false)
         }
 
         if ($with_gateway) {
-            $master_list[] = ['host' => $dns, 'gateway' => $gateway];
+            $master_list[] = [
+                'host' => $dns,
+                'gateway' => $gateway,
+                'interface' => $dnsif,
+                'source' => 'config',
+            ];
         } else {
             $master_list[] = $dns;
         }
     }
 
-    /* XXX check for overlapping host routes in gateway mode? */
+    if (!$with_gateway) {
+        $master_list = array_unique($master_list);
+    }
 
-    return array_unique($master_list, SORT_REGULAR);
+    return $master_list;
 }
 
 function system_hosts_generate($verbose = false)

src/opnsense/scripts/system/nameservers.php

@@ -32,4 +32,4 @@ require_once 'system.inc';
 require_once 'util.inc';
 require_once 'interfaces.inc';
 
-echo json_encode(get_nameservers()) . PHP_EOL;
+echo json_encode(get_nameservers(null, !empty($argv[1]))) . PHP_EOL;

src/opnsense/service/conf/actions.d/actions_system.conf

@@ -75,7 +75,7 @@ description: HA update and reconfigure backup
 
 [list.nameservers]
 command:/usr/local/opnsense/scripts/system/nameservers.php
-parameters:
+parameters:%s
 type:script_output
 message:list nameservers