public void RemoveEmptyCascadedTest()
{
string input, result, expected;
var sanitizer = new HtmlSanitizer();
sanitizer.WhiteListMode = true;
sanitizer.Tag("span").RemoveEmpty();
sanitizer.Tag("font").RemoveEmpty().AllowAttributes("id");
// The font tag is empty and will be removed. This results in the span tag also being empty, which would
// lead one to expect the span tag to be removed completely.
input = @"<span><font></font></span>";
expected = @"";
result = sanitizer.Sanitize(input);
Assert.Equal(expected, result);
}
public void TagRenameTest()
{
var input = "<b>before</b> <strong>content</strong> after<b></b>";
var expected = "<strong>before</strong> <strong>content</strong> after";
string result;
var sanitizer = new HtmlSanitizer();
sanitizer.Tag("strong").RemoveEmpty();
sanitizer.Tag("b").Rename("strong").RemoveEmpty();
sanitizer.Tag("i").RemoveEmpty();
sanitizer.Tag("a").SetAttribute("target", "_blank")
.SetAttribute("rel", "nofollow")
.CheckAttributeUrl("href")
.RemoveEmpty();
result = sanitizer.Sanitize(input);
Assert.Equal(expected, result);
}
public void RemoveEmptyTest()
{
string input, result, expected;
var sanitizer = new HtmlSanitizer();
sanitizer.WhiteListMode = true;
sanitizer.Tag("span").RemoveEmpty();
sanitizer.Tag("font").RemoveEmpty().AllowAttributes("id");
// Simply empty tags must be removed if instructed to do so.
input = @"<span>Test test<font></font></span>";
expected = @"<span>Test test</span>";
result = sanitizer.Sanitize(input);
Assert.Equal(expected, result);
// While empty content wise, it does have attributes. It should not simply be removed.
input = @"<span>Test test<font id=""test-id""></font></span>";
expected = @"<span>Test test<font id=""test-id""></font></span>";
result = sanitizer.Sanitize(input);
Assert.Equal(expected, result);
// The font tag is not really empty as it contains a space.
input = @"<span>Test test<font> </font></span>";
expected = @"<span>Test test<font> </font></span>";
result = sanitizer.Sanitize(input);
Assert.Equal(expected, result);
// The font tag is not really empty as it contains a linebreak.
input = @"<span>Test test<font>
</font></span>";
expected = @"<span>Test test<font>
</font></span>";
result = sanitizer.Sanitize(input);
Assert.Equal(expected, result);
// The unclosed font tag should not show up at all, and at least be removed because it is empty.
input = @"<span>Test test<font></span>";
expected = @"<span>Test test</span>";
result = sanitizer.Sanitize(input);
Assert.Equal(expected, result);
}
public void TagFlattenTests()
{
var input = @"<p>Some prepended content</p>
<p>before <span><b>Preserve before</b> content <i>Preserve</i></span> after</p>
<p>Some trailing content</p>";
var expected = @"<p>Some prepended content</p>
<p>before <b>Preserve before</b> content <i>Preserve</i> after</p>
<p>Some trailing content</p>";
string result;
var sanitizer = new HtmlSanitizer();
sanitizer.Tag("span").Operation(SanitizerOperation.FlattenTag);
sanitizer.Tag("i");
sanitizer.Tag("b");
sanitizer.Tag("p");
// Test flatten
result = sanitizer.Sanitize(input);
Assert.Equal(expected, result);
}
public void UnescapedAttributeTest()
{
string result;
var sanitizer = new HtmlSanitizer();
sanitizer.Tag("span").AllowAttributes("style");
var input = @"<span style=""<strong>Whats this?</strong>"">Text</span>";
result = sanitizer.Sanitize(input);
Assert.Equal(input, result);
}
public void DivStackOverflowAttempt()
{
string result;
var sanitizer = new HtmlSanitizer();
sanitizer.Tag("div");
sanitizer.MaxRecursionDepth = 10;
// Test some illegal href
var input = @"<meta http-equiv=""Content-Type"" content=""text/html; charset=utf-8""><div class=""reply-body""> <div> <span style=""font-family: arial, helvetica, sans-serif;""><span style=""font-size: 14px;""><span style=""color: #000000;"">Hi friend,</span></span> </span> </div> </div> <div> <div class=""reply-body""> </div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div> ";
Assert.Throws <InvalidOperationException>(() => { result = sanitizer.Sanitize(input); });
}
public void AttributeWhiteListing()
{
string result;
var sanitizer = new HtmlSanitizer();
sanitizer.Tag("input").AllowAttributes("whitelisted");
var input = @"<input nonwhitelisted="""" whitelisted="""">";
var expected = @"<input whitelisted="""">";
result = sanitizer.Sanitize(input);
Assert.Equal(expected, result);
}
public void EmptyAttributeTest()
{
string result;
var sanitizer = new HtmlSanitizer();
sanitizer.Tag("input").AllowAttributes("disabled value");
var input = @"<input disabled value=""test"">";
var expected = @"<input disabled="""" value=""test"">";
result = sanitizer.Sanitize(input);
Assert.Equal(expected, result);
}
public void ImgSrcUrlCheckRelativeTest()
{
string result;
var sanitizer = new HtmlSanitizer();
sanitizer.Tag("img").CheckAttributeUrl("src");
// Test a relative url, which should pass.
var input = @"<img src=""../relative.png"">";
var expected = @"<img src=""../relative.png"">";
result = sanitizer.Sanitize(input);
Assert.Equal(expected, result);
}
public void InvalidUrlEncodingTest()
{
string result;
var sanitizer = new HtmlSanitizer();
sanitizer.Tag("a").CheckAttributeUrl("href");
// Test a relative url, which should pass.
var input = @"<a href=""mailto:[email protected]?subject=test this"">MailTo</a>";
var expected = @"<a href=""mailto:[email protected]?subject=test this"">MailTo</a>";
result = sanitizer.Sanitize(input);
Assert.NotEqual(expected, result);
}
public void AHrefUrlCheckRelativeTest()
{
string result;
var sanitizer = new HtmlSanitizer();
sanitizer.Tag("a").CheckAttributeUrl("href");
// Test a relative url, which should pass.
var input = @"<a href=""../relative.htm"">Relative link</a>";
var expected = @"<a href=""../relative.htm"">Relative link</a>";
result = sanitizer.Sanitize(input);
Assert.Equal(expected, result);
}
public void CustomAttributeSanitization()
{
string result;
var sanitizer = new HtmlSanitizer();
var attributeSanitizer = new CustomSanitizer();
sanitizer.Tag("span").SanitizeAttributes("style", attributeSanitizer);
var input = @"<span style=""heading"">Text</span>";
var expected = @"<span style=""123"">Text</span>";
result = sanitizer.Sanitize(input);
Assert.Equal(expected, result);
}
public void DivRecursionAttempt()
{
string result;
var sanitizer = new HtmlSanitizer();
sanitizer.Tag("div");
sanitizer.MaxRecursionDepth = 10;
// Test 11 nested div elements
var input = @"
<div> <div> <div> <div> <div> <div> <div> <div> <div> <div> <div>
</div></div></div></div></div></div></div></div></div></div></div>";
Assert.Throws <InvalidOperationException>(() => { result = sanitizer.Sanitize(input); });
}
public void RuleOperationTests()
{
var input = "before <span>content</span> after";
var remove = "before after";
var flatten = "before content after";
string result;
var sanitizer = new HtmlSanitizer();
// Test do nothing
sanitizer.Tag("span").Operation(SanitizerOperation.DoNothing);
result = sanitizer.Sanitize(input);
Assert.Equal(input, result);
// Test flatten
sanitizer.Tag("span").Operation(SanitizerOperation.FlattenTag);
result = sanitizer.Sanitize(input);
Assert.Equal(flatten, result);
// Test remove
sanitizer.Tag("span").Operation(SanitizerOperation.RemoveTag);
result = sanitizer.Sanitize(input);
Assert.Equal(remove, result);
}
public void AHrefUrlDataUriCheckTest()
{
string result;
var sanitizer = new HtmlSanitizer();
sanitizer.Tag("a").CheckAttribute("href", HtmlSanitizerCheckType.Url);
// Test some well formed href
var inputLegal = @"<a href=""data:image/svg+xml;base64,UEsDBBQAAAAI"">That XSS trick</a>";
result = sanitizer.Sanitize(inputLegal);
Assert.Equal(inputLegal, result);
// Test a illegal
var inputIllegal = @"<a href=""data:html/text;base64,UEsDBBQAAAAI"">That XSS trick</a>";
result = sanitizer.Sanitize(inputIllegal);
Assert.Equal("That XSS trick", result);
}
public void ImgSrcUrlCheckTest()
{
string result;
var sanitizer = new HtmlSanitizer();
sanitizer.Tag("img").CheckAttributeUrl("src");
// Test some illegal href
var inputIllegal = @"<img src=""javascript:alert('test')"">";
var expectedIllegal = @"";
result = sanitizer.Sanitize(inputIllegal);
Assert.Equal(expectedIllegal, result);
// Test a legal well formed url
var inputLegal = @"<img src=""http://www.google.com/a.png"">";
result = sanitizer.Sanitize(inputLegal);
Assert.Equal(inputLegal, result);
}
public void AHrefUrlCheckTestLegacy()
{
string result;
var sanitizer = new HtmlSanitizer();
sanitizer.Tag("a").CheckAttributeUrl("href");
// Test some illegal href
var inputIllegal = @"<a href=""javascript:alert('test')"">That XSS trick</a>";
var expectedIllegal = @"That XSS trick";
result = sanitizer.Sanitize(inputIllegal);
Assert.Equal(expectedIllegal, result);
// Test a legal well formed url
var inputLegal = @"<a href=""http://www.google.com/"">Legal link</a>";
result = sanitizer.Sanitize(inputLegal);
Assert.Equal(inputLegal, result);
}
/// <summary>
/// Returns an instance of the HtmlSanitizer with a HTML5 compliant rule set for documents with simple markup.
/// </summary>
/// <remarks>Strips all CSS and only allows simple links. Enfores nofollow.</remarks>
/// <returns></returns>
public static HtmlSanitizer SimpleHtml5Sanitizer()
{
var sanitizer = new HtmlSanitizer();
sanitizer.WhiteListMode = true;
sanitizer.Tag("h1").RemoveEmpty();
sanitizer.Tag("h2").RemoveEmpty();
sanitizer.Tag("h3").RemoveEmpty();
sanitizer.Tag("h4").RemoveEmpty();
sanitizer.Tag("h5").RemoveEmpty();
sanitizer.Tag("strong").RemoveEmpty();
sanitizer.Tag("b").Rename("strong").RemoveEmpty();
sanitizer.Tag("i").RemoveEmpty();
sanitizer.Tag("em");
sanitizer.Tag("br");
sanitizer.Tag("p");
sanitizer.Tag("div").NoAttributes(SanitizerOperation.FlattenTag);
sanitizer.Tag("span").RemoveEmpty();
sanitizer.Tag("ul");
sanitizer.Tag("ol");
sanitizer.Tag("li");
sanitizer.Tag("a").SetAttribute("target", "_blank")
.SetAttribute("rel", "nofollow")
.CheckAttribute("href", HtmlSanitizerCheckType.Url)
.RemoveEmpty()
.NoAttributes(SanitizerOperation.FlattenTag);
return(sanitizer);
}
/// <summary>
/// White lists the specified HTML tag, creating a rule for it which allows further specification of what is to be done
/// with the tag.
/// </summary>
/// <param name="sanitizer"></param>
/// <param name="tagName"></param>
/// <returns></returns>
public static HtmlSanitizerTagRule Tag(this HtmlSanitizer sanitizer, string tagName)
{
return(sanitizer.Tag(tagName, true));
}
/// <summary>
/// Returns an instance of the HtmlSanitizer with a HTML5 compliant rule set for documents with simple markup.
/// </summary>
/// <remarks>Strips all CSS and only allows simple links. Enfores nofollow.</remarks>
/// <returns></returns>
public static HtmlSanitizer SimpleHtml5Sanitizer()
{
var sanitizer = new HtmlSanitizer();
sanitizer.WhiteListMode = true;
sanitizer.AllowCssClassAttribute = true;
sanitizer.Tag("script").Remove();
sanitizer.Tag("header").RemoveEmpty();
sanitizer.Tag("h1").RemoveEmpty();
sanitizer.Tag("h2").RemoveEmpty();
sanitizer.Tag("h3").RemoveEmpty();
sanitizer.Tag("h4").RemoveEmpty();
sanitizer.Tag("h5").RemoveEmpty();
sanitizer.Tag("strong").RemoveEmpty();
sanitizer.Tag("b").Rename("strong").RemoveEmpty();
sanitizer.Tag("i").RemoveEmpty();
sanitizer.Tag("em");
sanitizer.Tag("code");
sanitizer.Tag("br");
sanitizer.Tag("hr");
sanitizer.Tag("p");
sanitizer.Tag("pre");
sanitizer.Tag("div").NoAttributes(SanitizerOperation.FlattenTag);
sanitizer.Tag("span").RemoveEmpty();
sanitizer.Tag("ul");
sanitizer.Tag("ol");
sanitizer.Tag("dl");
sanitizer.Tag("dt");
sanitizer.Tag("li");
sanitizer.Tag("a").SetAttribute("target", "_blank")
.SetAttribute("rel", "nofollow")
.CheckAttribute("href", HtmlSanitizerCheckType.Url)
.RemoveEmpty()
.NoAttributes(SanitizerOperation.FlattenTag);
sanitizer.Tag("img")
.CheckAttribute("src", HtmlSanitizerCheckType.UrlOrBase64Data)
.AllowAttributes("alt height width rel")
.NoAttributes(SanitizerOperation.RemoveTag);
return(sanitizer);
}