use html5ever::{tendril::SliceExt, tokenizer::{BufferQueue, TagKind, Token, TokenSink, TokenSinkResult, Tokenizer}}; use comrak::{markdown_to_html, Options}; pub type Cloaker = Box String>; #[derive(Default)] pub struct Sanitizer { pub cloaker: Option, pub buffer: String, } pub fn safe_html(text: &str) -> String { Sanitizer::default().html(text) } pub fn safe_markdown(text: &str) -> String { Sanitizer::default().markdown(text) } impl Sanitizer { pub fn new(cloak: Cloaker) -> Self { Self { buffer: String::default(), cloaker: Some(cloak), } } pub fn markdown(self, text: &str) -> String { self.html(&markdown_to_html(text, &Options::default())) } pub fn html(self, text: &str) -> String { let mut input = BufferQueue::default(); input.push_back(text.to_tendril().try_reinterpret().unwrap()); let mut tok = Tokenizer::new(self, Default::default()); let _ = tok.feed(&mut input); if !input.is_empty() { tracing::warn!("buffer input not empty after processing html"); } tok.end(); tok.sink.buffer } } impl TokenSink for Sanitizer { type Handle = (); /// Each processed token will be handled by this method fn process_token(&mut self, token: Token, _line_number: u64) -> TokenSinkResult<()> { match token { Token::TagToken(tag) => { if !matches!( tag.name.as_ref(), "h1" | "h2" | "h3" | "hr" | "br" | "p" | "b" | "i" | "blockquote" | "pre" | "code" | "ul" | "ol" | "li" | "img" | "a" ) { return TokenSinkResult::Continue } // skip this tag self.buffer.push('<'); if !tag.self_closing && matches!(tag.kind, TagKind::EndTag) { self.buffer.push('/'); } self.buffer.push_str(tag.name.as_ref()); if !matches!(tag.kind, TagKind::EndTag) { match tag.name.as_ref() { "img" => for attr in tag.attrs { match attr.name.local.as_ref() { "src" => { let src = if let Some(ref cloak) = self.cloaker { cloak(attr.value.as_ref()) } else { attr.value.to_string() }; self.buffer.push_str(&format!(" src=\"{src}\"")) }, "title" => self.buffer.push_str(&format!(" title=\"{}\"", attr.value.as_ref())), "alt" => self.buffer.push_str(&format!(" alt=\"{}\"", attr.value.as_ref())), _ => {}, } }, "a" => { let any_attr = !tag.attrs.is_empty(); for attr in tag.attrs { match attr.name.local.as_ref() { "href" => self.buffer.push_str(&format!(" href=\"{}\"", attr.value.as_ref())), "title" => self.buffer.push_str(&format!(" title=\"{}\"", attr.value.as_ref())), "class" => if attr.value.as_ref() == "u-url mention" { self.buffer.push_str(" class=\"u-url mention\"") }, _ => {}, } } if any_attr { self.buffer.push_str(" rel=\"nofollow noreferrer\" target=\"_blank\""); } }, _ => {}, } } if tag.self_closing { self.buffer.push('/'); } self.buffer.push('>'); }, Token::CharacterTokens(txt) => self.buffer.push_str(txt.as_ref()), Token::CommentToken(_) => {}, Token::DoctypeToken(_) => {}, Token::NullCharacterToken => {}, Token::EOFToken => {}, Token::ParseError(e) => tracing::error!("error parsing html: {e}"), } TokenSinkResult::Continue } }