DHCP leases: do not link to WOL page if WOL plugin is missing

(cherry picked from commit 46e132f8)
(cherry picked from commit 77dedce0)

src/www/status_dhcp_leases.php

@@ -76,6 +76,8 @@ function remove_duplicate($array, $field)
 
 $interfaces = legacy_config_get_interfaces(array('virtual' => false));
 $leasesfile = services_dhcpd_leasesfile();
+/* Check if WOL plugin is installed */
+$plugin_installed = count(plugins_scan('wol'));
 
 if ($_SERVER['REQUEST_METHOD'] === 'GET') {
     $awk = "/usr/bin/awk";
@@ -417,9 +419,16 @@ include("head.inc");?>
                   <td><?=$data['int'];?></td>
                   <td><?=$data['ip'];?></td>
                   <td>
+<?php
+                      if ($plugin_installed): ?>
                       <a href="services_wol.php?if=<?=$data['if'];?>&amp;mac=<?=$data['mac'];?>" title="<?=gettext("send Wake on LAN packet to this MAC address");?>">
                         <?=$data['mac'];?>
                       </a>
+<?php
+                      else: ?>
+                        <?=$data['mac'];?>
+<?php
+                      endif; ?>
                       <br />
                       <small><i><?=!empty($mac_man[$mac_hi]) ? $mac_man[$mac_hi] : "";?></i></small>
                   </td>
@@ -437,9 +446,13 @@ include("head.inc");?>
                       </a>
 <?php
                     endif;?>
+<?php
+                    if ($plugin_installed): ?>
                     <a class="btn btn-default btn-xs" href="services_wol_edit.php?if=<?=$data['if'];?>&amp;mac=<?=$data['mac'];?>&amp;descr=<?=$data['hostname'];?>">
                       <span class="glyphicon glyphicon-flash" data-toggle="tooltip"  title="<?=gettext("add a Wake on LAN mapping for this MAC address");?>" alt="add"></span>
                     </a>
+<?php
+                    endif;?>
 <?php
                     if (($data['type'] == "dynamic") && ($data['online'] != "online")):?>