}[http://travis-ci.org/rgrove/sanitize]
== Installation
Latest stable release:
gem install sanitize
Latest development version:
gem install sanitize --pre
== Usage
If you don't specify any configuration options, Sanitize will use its strictest
settings by default, which means it will strip all HTML and leave only text
behind.
require 'rubygems'
require 'sanitize'
html = 'foo
'
Sanitize.clean(html) # => 'foo'
...
# or sanitize an entire HTML document (example assumes _html_ is whitelisted)
html = 'foo'
Sanitize.clean_document(html) # => '\nfoo\n'
== Configuration
In addition to the ultra-safe default settings, Sanitize comes with three other
built-in modes.
=== Sanitize::Config::RESTRICTED
Allows only very simple inline formatting markup. No links, images, or block
elements.
Sanitize.clean(html, Sanitize::Config::RESTRICTED) # => 'foo'
=== Sanitize::Config::BASIC
Allows a variety of markup including formatting tags, links, and lists. Images
and tables are not allowed, links are limited to FTP, HTTP, HTTPS, and mailto
protocols, and a rel="nofollow" attribute is added to all links to
mitigate SEO spam.
Sanitize.clean(html, Sanitize::Config::BASIC)
# => 'foo'
=== Sanitize::Config::RELAXED
Allows an even wider variety of markup than BASIC, including images and tables.
Links are still limited to FTP, HTTP, HTTPS, and mailto protocols, while images
are limited to HTTP and HTTPS. In this mode, rel="nofollow" is not
added to links.
Sanitize.clean(html, Sanitize::Config::RELAXED)
# => 'foo'
=== Custom Configuration
If the built-in modes don't meet your needs, you can easily specify a custom
configuration:
Sanitize.clean(html, :elements => ['a', 'span'],
:attributes => {'a' => ['href', 'title'], 'span' => ['class']},
:protocols => {'a' => {'href' => ['http', 'https', 'mailto']}})
==== :add_attributes (Hash)
Attributes to add to specific elements. If the attribute already exists, it will
be replaced with the value specified here. Specify all element names and
attributes in lowercase.
:add_attributes => {
'a' => {'rel' => 'nofollow'}
}
==== :attributes (Hash)
Attributes to allow for specific elements. Specify all element names and
attributes in lowercase.
:attributes => {
'a' => ['href', 'title'],
'blockquote' => ['cite'],
'img' => ['alt', 'src', 'title']
}
If you'd like to allow certain attributes on all elements, use the symbol
:all instead of an element name.
:attributes => {
:all => ['class'],
'a' => ['href', 'title']
}
==== :allow_comments (boolean)
Whether or not to allow HTML comments. Allowing comments is strongly
discouraged, since IE allows script execution within conditional comments. The
default value is false.
==== :elements (Array)
Array of element names to allow. Specify all names in lowercase.
:elements => %w[
a abbr b blockquote br cite code dd dfn dl dt em i kbd li mark ol p pre
q s samp small strike strong sub sup time u ul var
]
==== :output (Symbol)
Output format. Supported formats are :html and :xhtml,
defaulting to :html.
==== :output_encoding (String)
Character encoding to use for HTML output. Default is utf-8.
==== :protocols (Hash)
URL protocols to allow in specific attributes. If an attribute is listed here
and contains a protocol other than those specified (or if it contains no
protocol at all), it will be removed.
:protocols => {
'a' => {'href' => ['ftp', 'http', 'https', 'mailto']},
'img' => {'src' => ['http', 'https']}
}
If you'd like to allow the use of relative URLs which don't have a protocol,
include the symbol :relative in the protocol array:
:protocols => {
'a' => {'href' => ['http', 'https', :relative]}
}
==== :remove_contents (boolean or Array)
If set to +true+, Sanitize will remove the contents of any non-whitelisted
elements in addition to the elements themselves. By default, Sanitize leaves the
safe parts of an element's contents behind when the element is removed.
If set to an array of element names, then only the contents of the specified
elements (when filtered) will be removed, and the contents of all other filtered
elements will be left behind.
The default value is false.
==== :transformers
Custom transformer or array of custom transformers to run using depth-first
traversal. See the Transformers section below for details.
==== :transformers_breadth
Custom transformer or array of custom transformers to run using breadth-first
traversal. See the Transformers section below for details.
==== :whitespace_elements (Array)
Array of lowercase element names that should be replaced with whitespace when
removed in order to preserve readability. For example,
foobarbaz will become
foo bar baz when the is removed.
By default, the following elements are included in the
:whitespace_elements array:
address article aside blockquote br dd div dl dt footer h1 h2 h3 h4 h5
h6 header hgroup hr li nav ol p pre section ul
=== Transformers
Transformers allow you to filter and modify nodes using your own custom logic,
on top of (or instead of) Sanitize's core filter. A transformer is any object
that responds to call() (such as a lambda or proc).
To use one or more transformers, pass them to the :transformers
config setting. You may pass a single transformer or an array of transformers.
Sanitize.clean(html, :transformers => [transformer_one, transformer_two])
==== Input
Each registered transformer's call() method will be called once for
each node in the HTML (including elements, text nodes, comments, etc.), and will
receive as an argument an environment Hash that contains the following items:
[:config]
The current Sanitize configuration Hash.
[:is_whitelisted]
true if the current node has been whitelisted by a previous
transformer, false otherwise. It's generally bad form to remove a
node that a previous transformer has whitelisted.
[:node]
A Nokogiri::XML::Node object representing an HTML node. The node may be an
element, a text node, a comment, a CDATA node, or a document fragment. Use
Nokogiri's inspection methods (element?, text?,
etc.) to selectively ignore node types you aren't interested in.
[:node_name]
The name of the current HTML node, always lowercase (e.g. "div" or "span").
For non-element nodes, the name will be something like "text", "comment",
"#cdata-section", "#document-fragment", etc.
[:node_whitelist]
Set of Nokogiri::XML::Node objects in the current document that have been
whitelisted by previous transformers, if any. It's generally bad form to
remove a node that a previous transformer has whitelisted.
[:traversal_mode]
Current node traversal mode, either :depth for depth-first (the
default mode) or :breadth for breadth-first.
==== Output
A transformer doesn't have to return anything, but may optionally return a Hash,
which may contain the following items:
[:node_whitelist]
Array or Set of specific Nokogiri::XML::Node objects to add to the document's
whitelist, bypassing the current Sanitize config. These specific nodes and all
their attributes will be whitelisted, but their children will not be.
If a transformer returns anything other than a Hash, the return value will be
ignored.
==== Processing
Each transformer has full access to the Nokogiri::XML::Node that's passed into
it and to the rest of the document via the node's document()
method. Any changes made to the current node or to the document will be
reflected instantly in the document and passed on to subsequently-called
transformers and to Sanitize itself. A transformer may even call Sanitize
internally to perform custom sanitization if needed.
Nodes are passed into transformers in the order in which they're traversed. By
default, depth-first traversal is used, meaning that markup is traversed from
the deepest node upward (not from the first node to the last node):
html = 'foo'
transformer = lambda{|env| puts env[:node_name] }
# Prints "text", "span", "div", "#document-fragment".
Sanitize.clean(html, :transformers => transformer)
You may use the :transformers_breadth config to specify one or more
transformers that should traverse nodes in breadth-first mode:
html = 'foo'
transformer = lambda{|env| puts env[:node_name] }
# Prints "#document-fragment", "div", "span", "text".
Sanitize.clean(html, :transformers_breadth => transformer)
Transformers have a tremendous amount of power, including the power to
completely bypass Sanitize's built-in filtering. Be careful! Your safety is in
your own hands.
==== Example: Transformer to whitelist YouTube video embeds
The following example demonstrates how to create a depth-first Sanitize
transformer that will safely whitelist valid YouTube video embeds without having
to blindly allow other kinds of embedded content, which would be the case if you
tried to do this by just whitelisting all