/// <summary>
/// Add allowed URL protocols for an element's URL attribute.
/// </summary>
/// <remarks>
/// This restricts the possible values of the attribute to
/// URLs with the defined protocol.
/// <p/>
/// E.g.: <c>AddProtocols("a", "href", "ftp", "http", "https")</c>
/// </remarks>
/// <param name="tag">Tag the URL protocol is for</param>
/// <param name="key">Attribute key</param>
/// <param name="protocols">List of valid protocols</param>
/// <returns>this, for chaining</returns>
public Whitelist AddProtocols(string tag, string key, params string[] protocols)
{
Validate.NotEmpty(tag);
Validate.NotEmpty(key);
Validate.NotNull(protocols);
Whitelist.TagName tagName = Whitelist.TagName.ValueOf(tag);
Whitelist.AttributeKey attrKey = Whitelist.AttributeKey.ValueOf(key);
IDictionary <Whitelist.AttributeKey, ICollection <Whitelist.Protocol> > attrMap;
ICollection <Whitelist.Protocol> protSet;
if (this.protocols.ContainsKey(tagName))
{
attrMap = this.protocols[tagName];
}
else
{
attrMap = new Dictionary <Whitelist.AttributeKey, ICollection <Whitelist.Protocol> >();
this.protocols[tagName] = attrMap;
}
if (attrMap.ContainsKey(attrKey))
{
protSet = attrMap[attrKey];
}
else
{
protSet = new HashSet <Whitelist.Protocol>();
attrMap[attrKey] = protSet;
}
foreach (string protocol in protocols)
{
Validate.NotEmpty(protocol);
Whitelist.Protocol prot = Whitelist.Protocol.ValueOf(protocol);
protSet.Add(prot);
}
return(this);
}
/// <summary>
/// Test if the supplied attribute is allowed by this whitelist for this tag
/// </summary>
/// <param name="tagName">tag to consider allowing the attribute in</param>
/// <param name="el">element under test, to confirm protocol</param>
/// <param name="attr">attribute under test</param>
/// <returns>true if allowed</returns>
internal bool IsSafeAttribute(string tagName, Element el, Nodes.Attribute attr)
{
Whitelist.TagName tag = Whitelist.TagName.ValueOf(tagName);
Whitelist.AttributeKey key = Whitelist.AttributeKey.ValueOf(attr.Key);
if (attributes.ContainsKey(tag))
{
if (attributes[tag].Contains(key))
{
if (protocols.ContainsKey(tag))
{
IDictionary <Whitelist.AttributeKey, ICollection <Whitelist.Protocol> > attrProts = protocols[tag];
// ok if not defined protocol; otherwise test
return(!attrProts.ContainsKey(key) || TestValidProtocol(el, attr, attrProts[key]));
}
else
{
// attribute found, no protocols defined, so OK
return(true);
}
}
}
// no attributes defined for tag, try :all tag
return(!tagName.Equals(":all") && IsSafeAttribute(":all", el, attr));
}
/// <summary>
/// Add an enforced attribute to a tag.
/// </summary>
/// <remarks>
/// An enforced attribute will always be added to the element. If the element
/// already has the attribute set, it will be overridden.
/// <p/>
/// E.g.: <c>AddEnforcedAttribute("a", "rel", "nofollow")</c> will make all <c>a</c> tags output as
/// <c><a href="..." rel="nofollow"></c>
/// </remarks>
/// <param name="tag">The tag the enforced attribute is for. The tag will be added to the allowed tag list if necessary.
/// </param>
/// <param name="key">The attribute key</param>
/// <param name="value">The enforced attribute value</param>
/// <returns>this (for chaining)</returns>
public Whitelist AddEnforcedAttribute(string tag, string key, string value)
{
Validate.NotEmpty(tag);
Validate.NotEmpty(key);
Validate.NotEmpty(value);
Whitelist.TagName tagName = Whitelist.TagName.ValueOf(tag);
if (!tagNames.Contains(tagName))
{
tagNames.Add(tagName);
}
Whitelist.AttributeKey attrKey = Whitelist.AttributeKey.ValueOf(key);
Whitelist.AttributeValue attrVal = Whitelist.AttributeValue.ValueOf(value);
if (enforcedAttributes.ContainsKey(tagName))
{
enforcedAttributes[tagName][attrKey] = attrVal;
}
else
{
IDictionary <Whitelist.AttributeKey, Whitelist.AttributeValue> attrMap = new Dictionary <Whitelist.AttributeKey, Whitelist.AttributeValue>();
attrMap[attrKey] = attrVal;
enforcedAttributes[tagName] = attrMap;
}
return(this);
}