internal AttributeWrapper(GumboAttribute attribute, ElementWrapper parent, int index,
Action<string, ElementWrapper> addElementWithId)
{
if (parent == null)
{
throw new ArgumentNullException("parent");
}
if (addElementWithId == null)
{
throw new ArgumentNullException("addElementWithId");
}
Parent = parent;
Index = index;
Name = NativeUtf8Helper.StringFromNativeUtf8(attribute.name);
Value = NativeUtf8Helper.StringFromNativeUtf8(attribute.value);
OriginalName = NativeUtf8Helper.StringFromNativeUtf8(attribute.original_name.data, (int)attribute.original_name.length);
OriginalValue = NativeUtf8Helper.StringFromNativeUtf8(attribute.original_value.data, (int)attribute.original_value.length);
NameStart = attribute.name_start;
NameEnd = attribute.name_end;
ValueStart = attribute.value_start;
ValueEnd = attribute.value_end;
Namespace = attribute.attr_namespace;
if (String.Equals(this.Name, "id", StringComparison.OrdinalIgnoreCase))
{
addElementWithId(this.Value, parent);
}
}
internal AttributeWrapper(GumboAttribute attribute, ElementWrapper parent)
{
if (parent == null)
{
throw new ArgumentNullException(nameof(parent));
}
Parent = parent;
Name = NativeUtf8Helper.StringFromNativeUtf8(attribute.name);
Value = NativeUtf8Helper.StringFromNativeUtf8(attribute.value);
OriginalName = NativeUtf8Helper.StringFromNativeUtf8(attribute.original_name.data, (int)attribute.original_name.length);
OriginalValue = NativeUtf8Helper.StringFromNativeUtf8(attribute.original_value.data, (int)attribute.original_value.length);
NameStart = attribute.name_start;
NameEnd = attribute.name_end;
ValueStart = attribute.value_start;
ValueEnd = attribute.value_end;
Namespace = attribute.attr_namespace;
}
internal AttributeWrapper(GumboAttribute attribute, ElementWrapper parent)
{
if (parent == null)
{
throw new ArgumentNullException(nameof(parent));
}
Parent = parent;
Name = NativeUtf8Helper.StringFromNativeUtf8(attribute.name);
Value = NativeUtf8Helper.StringFromNativeUtf8(attribute.value);
OriginalName = NativeUtf8Helper.StringFromNativeUtf8(attribute.original_name.data, (int)attribute.original_name.length);
OriginalValue = NativeUtf8Helper.StringFromNativeUtf8(attribute.original_value.data, (int)attribute.original_value.length);
NameStart = attribute.name_start;
NameEnd = attribute.name_end;
ValueStart = attribute.value_start;
ValueEnd = attribute.value_end;
Namespace = attribute.attr_namespace;
}
private bool ValidateNode(ElementWrapper node, InsertionsMap insertionsMap, ref RequestValidationParam dangerousParam)
{
var result = true;
foreach (
var element in node.Children.OfType<ElementWrapper>())
{
var elementStart = (int)element.StartPosition.offset;
var elementEnd = (int)element.EndPosition.offset;
foreach (
var insertionArea in
insertionsMap.Where(ia => ia.Includes(elementStart, elementEnd)))
{
// Check if start position of node was included to insertions map
if (insertionArea.Includes(elementStart))
{
// Inclusion found (node was injected by request parameter)
dangerousParam = insertionArea.Param;
return false;
}
foreach (var attr in element.Attributes)
{
var attrNameStart = (int)attr.NameStart.offset;
if (insertionArea.Includes(attrNameStart))
{
// Inclusion found (attribute was injected by request parameter)
dangerousParam = insertionArea.Param;
return false;
}
var attrValueStart = (int)attr.ValueStart.offset;
var attrValueEnd = (int)attr.ValueEnd.offset;
// Skip if attribute value wasn't tainted by request parameter
if (!insertionArea.Includes(attrValueStart, attrValueEnd)) continue;
// Skip if attribute value passes validation
if (ValidateAttribute(attr.Name, attr.Value, insertionArea.Param.Value)) continue;
// Attribute value is dangerously tainted
dangerousParam = insertionArea.Param;
return false;
}
}
if (element.Tag == GumboTag.GUMBO_TAG_SCRIPT && element.Children.Any(child => child is TextWrapper))
{
var text = element.Children.OfType<TextWrapper>().FirstOrDefault();
if (text != null)
{
// Validate javscript code inside <script /> tag
foreach (
var insertionArea in
insertionsMap.Where(
ia =>
ia.Includes((int) text.StartPosition.offset,
(int) text.StartPosition.offset + text.Text.Length))
.Where(insertionArea => !ValidateJavascript(text.Text, insertionArea.Param.Value)))
{
// Javascript code is dangerously tainted
dangerousParam = insertionArea.Param;
return false;
}
}
}
// TODO: Add integrity validation of style nodes here
result &= ValidateNode(element, insertionsMap, ref dangerousParam);
}
return result;
}
private void AddElementWithId(string id, ElementWrapper element)
{
List<ElementWrapper> elements;
if (!ElementsWithIds.TryGetValue(id, out elements))
{
elements = new List<ElementWrapper>();
ElementsWithIds.Add(id, elements);
}
elements.Add(element);
}
private static void MarshalElementAndDescendants(ElementWrapper element)
{
GC.KeepAlive(element.Attributes);
foreach (var child in element.Children.OfType<ElementWrapper>())
{
MarshalElementAndDescendants(child);
}
}