unbound: Fix "register DHCP leases in DNS" config option

The option to register DHCP leases within unbound DNS was configurable via
DNS Resolver GUI, but the setting was ignored. DHCP leases were always applied.

(cherry picked from commit 4f116228)

src/etc/inc/unbound.inc

@@ -549,18 +549,20 @@ function unbound_add_host_entries() {
     }
 
     // Handle DHCPLeases added host entries
-    $dhcplcfg = read_hosts();
-    $host_entries = "";
-    if (is_array($dhcplcfg)) {
-        foreach($dhcplcfg as $key=>$host) {
-            $host_entries .= "local-data-ptr: \"{$host['ipaddr']} {$host['fqdn']}\"\n";
-            $host_entries .= "local-data: \"{$host['fqdn']} IN A {$host['ipaddr']}\"\n";
-            if (!empty($host['name'])) {
-                $host_entries .= "local-data-ptr: \"{$host['ipaddr']} {$host['name']}\"\n";
-                $host_entries .= "local-data: \"{$host['name']} IN A {$host['ipaddr']}\"\n";
+    if (isset($config['unbound']['regdhcp'])) {
+        $dhcplcfg = read_hosts();
+        $host_entries = "";
+        if (is_array($dhcplcfg)) {
+            foreach($dhcplcfg as $key=>$host) {
+                $host_entries .= "local-data-ptr: \"{$host['ipaddr']} {$host['fqdn']}\"\n";
+                $host_entries .= "local-data: \"{$host['fqdn']} IN A {$host['ipaddr']}\"\n";
+                if (!empty($host['name'])) {
+                    $host_entries .= "local-data-ptr: \"{$host['ipaddr']} {$host['name']}\"\n";
+                    $host_entries .= "local-data: \"{$host['name']} IN A {$host['ipaddr']}\"\n";
+                }
             }
+            $unbound_entries .= $host_entries;
         }
-        $unbound_entries .= $host_entries;
     }
 
     // Write out entries