HTML Sanitization
Ammonia is a whitelist-based HTML sanitization library. It is designed to
prevent cross-site scripting, layout breaking, and clickjacking caused
by untrusted user-provided HTML being mixed into a larger web page.
Ammonia uses html5ever to parse and serialize document fragments the same way browsers do,
so it is extremely resilient to syntactic obfuscation.
Ammonia parses its input exactly according to the HTML5 specification;
it will not linkify bare URLs, insert line or paragraph breaks, or convert (C) into ©.
If you want that, use a markup processor before running the sanitizer, like pulldown-cmark.
Installation
To use ammonia, add it to your project's Cargo.toml file:
[dependencies]
ammonia = "3"
Changes
Please see the CHANGELOG for a release history.
Example
Using pulldown-cmark together with Ammonia for a friendly user-facing comment
site.
use ammonia::clean;
use pulldown_cmark::{Parser, Options, html::push_html};
let text = "[a link](http://www.notriddle.com/)";
let mut options = Options::empty();
options.insert(Options::ENABLE_TABLES);
let mut md_parse = Parser::new_ext(text, options);
let mut unsafe_html = String::new();
push_html(&mut unsafe_html, md_parse);
let safe_html = clean(&*unsafe_html);
assert_eq!(safe_html, "<a href=\"http://www.notriddle.com/\">a link</a>");
Performance
Ammonia builds a DOM, traverses it (replacing unwanted nodes along the way),
and serializes it again. It could be faster for what it does, and if you don't
want to allow any HTML it is possible to be even faster than that.
However, it takes about fifteen times longer to sanitize an HTML string using
bleach-2.0.0 with html5lib-0.999999999 than it does using Ammonia 1.0.
$ cd benchmarks
$ cargo run --release
Running `target/release/ammonia_bench`
87539 nanoseconds to clean up the intro to the Ammonia docs.
$ python bleach_bench.py
(1498800.015449524, 'nanoseconds to clean up the intro to the Ammonia docs.')
License
Licensed under either of these:
- Apache License, Version 2.0, (LICENSE-APACHE or
http://www.apache.org/licenses/LICENSE-2.0) - MIT license (LICENSE-MIT or
http://opensource.org/licenses/MIT)
Thanks
Thanks to the other sanitizer libraries, particularly Bleach for Python and sanitize-html for Node,
which we blatantly copied most of our API from.
Thanks to ChALkeR, whose Improper Markup Sanitization document helped us find high-level semantic holes in Ammonia,
to ssokolow, whose review and experience were also very helpful, to securityMB,
for finding a very obscure namespace-related injection bug, and xfix for finding a DoS bug in a recursive destructor.
And finally, thanks to the contributors.