--- a/msitegen.inc.php	Fri Nov 08 12:08:16 2013 +0200
+++ b/msitegen.inc.php	Fri Nov 08 18:54:54 2013 +0200
@@ -9,11 +9,19 @@
 $errorSet = FALSE;
 $errorMsg = "";
 
+// Value types
 define("VT_STR", 1);
 define("VT_INT", 2);
 define("VT_BOOL", 3);
 define("VT_TEXT", 4);
 
+// Validation check types
+define("CHK_TYPE", 1);
+define("CHK_ISLT", 2);
+define("CHK_ISGT", 3);
+define("CHK_ISEQ", 4);
+define("CHK_CUSTOM", 5);
+
 
 function stDebug($msg)
 {
@@ -206,15 +214,97 @@
 }
 
 
-function stChkDataItem($name)
+function stErrorStrF($msg, $data)
 {
-  return !isset($_REQUEST[$name]) || strlen(trim($_REQUEST[$name])) < 1;
+  stError($msg);
+  return FALSE;
 }
 
 
-function stChkRequestItem($name)
+//
+// Check and validate one item from $_REQUEST[], based on
+// list of validation conditions. For example:
+//
+//  stChkRequestItem("name", FALSE,
+//    array(CHK_ISGT, VT_STR, 0, "Handle / name not given."),
+//    array(CHK_ISGT, VT_STR, 3, "Handle / name too short, should be 3 characters or more."),
+//    array(CHK_ISLT, VT_STR, SET_LEN_USERNAME, "Handle / name is too long, should be less than ".SET_LEN_USERNAME." characters."));
+//
+function stChkRequestItem($name, &$sdata)
 {
-  return isset($_REQUEST[$name]);
+  if (!isset($_REQUEST[$name]))
+    return FALSE;
+
+  $data = trim($_REQUEST[$name]);
+  $slen = strlen($data);
+
+  if ($sdata !== FALSE)
+    $sdata = $data;
+
+  // Go through list of validation checks
+  $argc = func_num_args();
+  $argv = func_get_args();
+
+  for ($argn = 2; $argn < $argc; $argn++)
+  {
+    // Act according to check type
+    $check = $argv[$argn];
+    switch ($check[0])
+    {
+      case CHK_TYPE:
+        // Check type of the data
+        switch ($check[1])
+        {
+          case VT_STR:
+            if ($slen == 0)
+              return stErrorStrF($check[2], $data);
+            break;
+
+          case VT_INT:
+          case VT_BOOL:
+            if ($slen == 0 || !is_numeric($data))
+              return stErrorStrF($check[2], $data);
+            break;
+        }
+        break;
+
+      case CHK_ISLT:
+      case CHK_ISGT:
+      case CHK_ISEQ:
+        // Check length or value of the data
+        switch ($check[1])
+        {
+          case VT_STR:
+          case VT_TEXT:
+            // Strings get their length checked
+            if (($check[0] == CHK_ISLT && $slen >= $check[2]) ||
+                ($check[0] == CHK_ISGT && $slen <= $check[2]) ||
+                ($check[0] == CHK_ISEQ && $slen != $check[2]))
+                return stErrorStrF($check[3], $data);
+            break;
+
+          case VT_INT:
+          case VT_BOOL:
+            // Integer values checked against .. value
+            $sval = to_int($data);
+            if (($check[0] == CHK_ISLT && $sval >= $check[2]) ||
+                ($check[0] == CHK_ISGT && $sval <= $check[2]) ||
+                ($check[0] == CHK_ISEQ && $sval != $check[2]))
+                return stErrorStrF($check[3], $data);
+            break;
+        }
+        break;
+
+      case CHK_CUSTOM:
+        // Call a custom function (or closure)
+        $func = $check[1];
+        if (!is_callable($func) || !$func($data))
+          return stErrorStrF($check[2], $data);
+        break;
+    }
+  }
+
+  return TRUE;
 }