Allow num_oid to use OCTET STRING indexes (#10410)

* make index available as OCTET STRING converted to OID
* codeclimate

doc/Developing/os/Health-Information.md

@@ -85,7 +85,8 @@ The only sensor we have defined here is airflow. The available options are as fo
   the value. If not provided willuse `oid`
 - `num_oid` (required): This is the numerical OID that contains
   `value`. This should always include `{{ $index }}`.  snmptranslate
-  -On can help figure out the number
+  -On can help figure out the number.
+  In case the index is a string, `{{ $index_string }}` can be used instead.
 - `divisor` (optional): This is the divisor to use against the returned `value`.
 - `multiplier` (optional): This is the multiplier to use against the returned `value`.
 - `low_limit` (optional): This is the critical low threshold that

includes/discovery/functions.inc.php

@@ -1047,6 +1047,9 @@ function discovery_process(&$valid, $device, $sensor_type, $pre_cache)
                 $skippedFromYaml = YamlDiscovery::canSkipItem($value, $index, $data, $sensor_options, $pre_cache);
                 if ($skippedFromYaml === false && is_numeric($value)) {
                     $oid = str_replace('{{ $index }}', $index, $data['num_oid']);
+                    // if index is a string, we need to convert it to OID
+                    // strlen($index) as first number, and each letter converted to a number, separated by dots
+                    $oid = str_replace('{{ $index_string }}', strlen($index) . '.' . implode(".", unpack("c*", $index)), $oid);
 
                     // process the description
                     $descr = YamlDiscovery::replaceValues('descr', $index, null, $data, $pre_cache);