2 files changed, 16 insertions, 8 deletions

diff --git a/graph.php b/graph.php
index 3e33b92..2d62d92 100644
--- a/graph.php
+++ b/graph.php
@@ -6,16 +6,24 @@ require_once 'inc/collectd.inc.php';
 
 $plugin = validate_get(GET('p'), 'plugin');
 $type = validate_get(GET('t'), 'type');
-$width = empty($_GET['x']) ? $CONFIG['width'] : $_GET['x'];
-$height = empty($_GET['y']) ? $CONFIG['height'] : $_GET['y'];
-
-if (validate_get(GET('h'), 'host') === NULL) {
-        error_log('CGP Error: plugin contains unknown characters');
+$width = GET('x') ? filter_input(INPUT_GET, 'x', FILTER_VALIDATE_INT, array(
+        'min_range' => 10,
+        'max_range' => $CONFIG['max-width']
+)) : $CONFIG['width'];
+$height = GET('y') ? filter_input(INPUT_GET, 'y', FILTER_VALIDATE_INT, array(
+        'min_range' => 10,
+        'max_range' => $CONFIG['max-height']
+)) : $CONFIG['height'];
+
+if ($width === NULL || $height === NULL) {
+        error_log(sprintf('Invalid image dimension, x="%s", y="%s"',
+                urlencode(GET('x')),
+                urlencode(GET('y'))));
         error_image();
 }
 
-if ($width > $CONFIG['max-width'] || $height > $CONFIG['max-height']) {
-        error_log('Resquested image is too large. Please configure max-width and max-height.');
+if (validate_get(GET('h'), 'host') === NULL) {
+        error_log('Invalid host: "' . urlencode(GET('h')) . '"');
         error_image();
 }
 
diff --git a/inc/functions.inc.php b/inc/functions.inc.php
index c32b3ef..3664d78 100644
--- a/inc/functions.inc.php
+++ b/inc/functions.inc.php
@@ -55,7 +55,7 @@ function crc32hex($str) {
 }
 
 function error_image() {
-        header("Content-Type: image/png");
+        header("Content-Type: image/png", true, 400);
         readfile('layout/error.png');
         exit;
 }