refactor: snmp cleanup (#4683)

includes/common.php

@@ -1461,6 +1461,30 @@ function starts_with($haystack, $needles, $case_insensitive = false)
     return false;
 }
 
+/**
+ * Search backwards for the $needle, returning $count found occurrence
+ *
+ * @param string $haystack
+ * @param string $needle
+ * @param int $count
+ * @return bool|int
+ */
+function strrpos_count($haystack, $needle, $count = 1)
+{
+    if ($count <= 0) {
+        return false;
+    }
+
+    $len = strlen($haystack);
+    $pos = $len;
+
+    for ($i = 0; $i < $count && $pos; $i++) {
+        $pos = strrpos($haystack, $needle, $pos - $len - 1);
+    }
+
+    return $pos;
+}
+
 function get_auth_ad_user_filter($username)
 {
     global $config;