add support for varnish plugin categories

Since commit collectd-4.10.0-88-g02e12db the varnish plugin groups collected
values in categories. The collectd filestructure used for varnish is now:

  <plugin>-<category>-<plugin_instance>/<type>-<type_instance>

Because this isn't distinguishable from a regular plugin like df, ...

  df-var-tmp/df_complex-free.rrd ("var" isn't the category here)

... the category is only set with the varnish plugin.

Reported-by: Jonathan Huot <jonathan.huot@gmail.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/inc/functions.inc.php b/inc/functions.inc.php
index 39f1cd0..a72a589 100644
--- a/inc/functions.inc.php
+++ b/inc/functions.inc.php
@@ -15,6 +15,7 @@ function validate_get($value, $type) {
                                 return NULL;
                 break;
                 case 'plugin':
+                case 'category':
                 case 'type':
                         if (!preg_match('/^\w+$/u', $value))
                                 return NULL;