func ExamplePolicy_Sanitize() {
// UGCPolicy is a convenience policy for user generated content.
p := bluemonday.UGCPolicy()
// string in, string out
html := p.Sanitize(`<a onblur="alert(secret)" href="http://www.google.com">Google</a>`)
fmt.Println(html)
// Output:
//<a href="http://www.google.com" rel="nofollow">Google</a>
}
func ExamplePolicy_SanitizeReader() {
// UGCPolicy is a convenience policy for user generated content.
p := bluemonday.UGCPolicy()
// io.Reader in, bytes.Buffer out
r := strings.NewReader(`<a onblur="alert(secret)" href="http://www.google.com">Google</a>`)
buf := p.SanitizeReader(r)
fmt.Println(buf.String())
// Output:
//<a href="http://www.google.com" rel="nofollow">Google</a>
}
func ExamplePolicy_SanitizeBytes() {
// UGCPolicy is a convenience policy for user generated content.
p := bluemonday.UGCPolicy()
// []byte in, []byte out
b := []byte(`<a onblur="alert(secret)" href="http://www.google.com">Google</a>`)
b = p.SanitizeBytes(b)
fmt.Println(string(b))
// Output:
//<a href="http://www.google.com" rel="nofollow">Google</a>
}
func Example() {
// Create a new policy
p := bluemonday.NewPolicy()
// Add elements to a policy without attributes
p.AllowElements("b", "strong")
// Add elements as a virtue of adding an attribute
p.AllowAttrs("nowrap").OnElements("td", "th")
// Attributes can either be added to all elements
p.AllowAttrs("dir").Globally()
//Or attributes can be added to specific elements
p.AllowAttrs("value").OnElements("li")
// It is ALWAYS recommended that an attribute be made to match a pattern
// XSS in HTML attributes is a very easy attack vector
// \p{L} matches unicode letters, \p{N} matches unicode numbers
p.AllowAttrs("title").Matching(regexp.MustCompile(`[\p{L}\p{N}\s\-_',:\[\]!\./\\\(\)&]*`)).Globally()
// You can stop at any time and call .Sanitize()
// Assumes that string htmlIn was passed in from a HTTP POST and contains
// untrusted user generated content
htmlIn := `untrusted user generated content <body onload="alert('XSS')">`
fmt.Println(p.Sanitize(htmlIn))
// And you can take any existing policy and extend it
p = bluemonday.UGCPolicy()
p.AllowElements("fieldset", "select", "option")
// Links are complex beasts and one of the biggest attack vectors for
// malicious content so we have included features specifically to help here.
// This is not recommended:
p = bluemonday.NewPolicy()
p.AllowAttrs("href").Matching(regexp.MustCompile(`(?i)mailto|https?`)).OnElements("a")
// The regexp is insufficient in this case to have prevented a malformed
// value doing something unexpected.
// This will ensure that URLs are not considered invalid by Go's net/url
// package.
p.RequireParseableURLs(true)
// If you have enabled parseable URLs then the following option will allow
// relative URLs. By default this is disabled and will prevent all local and
// schema relative URLs (i.e. `href="//www.google.com"` is schema relative).
p.AllowRelativeURLs(true)
// If you have enabled parseable URLs then you can whitelist the schemas
// that are permitted. Bear in mind that allowing relative URLs in the above
// option allows for blank schemas.
p.AllowURLSchemes("mailto", "http", "https")
// Regardless of whether you have enabled parseable URLs, you can force all
// URLs to have a rel="nofollow" attribute. This will be added if it does
// not exist.
// This applies to "a" "area" "link" elements that have a "href" attribute
p.RequireNoFollowOnLinks(true)
// We provide a convenience function that applies all of the above, but you
// will still need to whitelist the linkable elements:
p = bluemonday.NewPolicy()
p.AllowStandardURLs()
p.AllowAttrs("cite").OnElements("blockquote")
p.AllowAttrs("href").OnElements("a", "area")
p.AllowAttrs("src").OnElements("img")
// Policy Building Helpers
// If you've got this far and you're bored already, we also bundle some
// other convenience functions
p = bluemonday.NewPolicy()
p.AllowStandardAttributes()
p.AllowImages()
p.AllowLists()
p.AllowTables()
}