fix: ping fails on servers that don't set PATH in cron (#7603)

* fix: ping fails on servers that don't set PATH in cron
Find the full path to fping and persist it in the database.
Adds the ability to persist settings with Config::set()

* Add ability to set webui settings.
No display of for paths, because it would be inconsistent.

includes/defaults.inc.php

@@ -42,8 +42,8 @@ $config['db_socket']             = null;
 $config['own_hostname'] = 'localhost';
 
 // Location of executables
-$config['fping']                    = 'fping';
-$config['fping6']                   = 'fping6';
+//$config['fping']                    = '/usr/sbin/fping';
+//$config['fping6']                   = '/usr/sbin/fping6';
 $config['fping_options']['retries'] = 3;
 $config['fping_options']['timeout'] = 500;
 $config['fping_options']['count']   = 3;

includes/functions.php

@@ -2318,3 +2318,23 @@ function return_num($entry)
         return $num_response[0];
     }
 }
+
+/**
+ * Locate the actual path of a binary
+ *
+ * @param $binary
+ * @return mixed
+ */
+function locate_binary($binary)
+{
+    if (!str_contains($binary, '/')) {
+        $output = `whereis -b $binary`;
+        $target = trim(substr($output, strpos($output, ':') + 1));
+
+        if (file_exists($target)) {
+            return $target;
+        }
+    }
+
+    return $binary;
+}

includes/process_config.inc.php

@@ -23,6 +23,8 @@
  * @author     Neil Lathwood <neil@lathwood.co.uk>
  */
 
+use LibreNMS\Config;
+
 if (empty($config['email_from'])) {
     $config['email_from'] = '"' . $config['project_name'] . '" <' . $config['email_user'] . '@' . php_uname('n') . '>';
 }
@@ -42,3 +44,10 @@ if ($config['secure_cookies']) {
 if ($config['rrdgraph_real_95th']) {
     $config['rrdgraph_real_percentile'] = $config['rrdgraph_real_95th'];
 }
+
+// make sure we have full path to binaries in case PATH isn't set
+foreach (array('fping', 'fping6') as $bin) {
+    if (!is_executable(Config::get($bin))) {
+        Config::set($bin, locate_binary($bin), true, $bin, "Path to $bin", 'external', 'paths');
+    }
+}