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Improve rich text rendering to more closely match the recommendations from the spec

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Bad 2020-10-26 22:55:54 +01:00
parent 1a8427925c
commit f46f9abe6e
1 changed files with 50 additions and 10 deletions
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60
src/js/events/message.js
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@ -4,28 +4,68 @@ const {resolveMxc} = require("../functions")
const {Event} = require("./event") const {Event} = require("./event")
const purifier = DOMPurify() const purifier = DOMPurify()
purifier.setConfig({
ALLOWED_URI_REGEXP: /^mxc:\/\/[a-zA-Z0-9\.]+\/[a-zA-Z0-9]+$/, // As per the spec we only allow mxc uris
ALLOWED_TAGS: ['font', 'del', 'h1', 'h2', 'h3', 'h4', 'h5', 'h6', 'blockquote', 'p', 'a', 'ul', 'ol', 'sup', 'sub', 'li', 'b', 'i', 'u', 'strong', 'em', 'strike', 'code', 'hr', 'br', 'div', 'table', 'thead', 'tbody', 'tr', 'th', 'td', 'caption', 'pre', 'span', 'img'],
// In case we mess up none of those attributes should read to XSS
ALLOWED_ATTR: ["data-mx-bg-color", "data-mx-color", "color",
"name", "target", "href",
"width", "height", "alt", "title", "src", "data-mx-emoticon",
"start", "class"],
//Custom config option that allows the array of attributes for a given tag
ALLOWED_ATTR_CUSTOM: {
"FONT": ["data-mx-bg-color", "data-mx-color", "color"],
"SPAN": ["data-mx-bg-color", "data-mx-color", "color"],
"A": ["name", "target", "href"],
"IMG": ["width", "height", "alt", "title", "src", "data-mx-emoticon"],
"OL": ["start"],
"CODE": ["class"],
}
})
//Handle our custom tag
purifier.addHook("uponSanitizeAttribute", (node, hookevent, config) => {
//If purifier already rejected an attribute there is no point in checking it
if (hookevent.keepAttr === false) return;
const allowed_attributes = config.ALLOWED_ATTR_CUSTOM[node.tagName] || []
hookevent.keepAttr = allowed_attributes.indexOf(hookevent.attrName) > -1;
})
//Remove bad classes from our code element
purifier.addHook("uponSanitizeElement", (node, hookevent, config) => {
if (node.tagName != "CODE") return
node.classList.forEach(c => {
if (!c.startsWith("language-")) {
node.classList.remove(c)
}
})
return node
})
purifier.addHook("afterSanitizeAttributes", (node, hookevent, config) => { purifier.addHook("afterSanitizeAttributes", (node, hookevent, config) => {
if (node.tagName == "img") { if (node.tagName == "IMG") {
let src = node.getAttribute("src") let src = node.getAttribute("src")
if (src) src = resolveMxc(src) if (src) src = resolveMxc(src)
node.setAttribute("src", src) node.setAttribute("src", src)
} else if (node.tagName == "A") {
}
if (node.tagName = "a") {
node.setAttribute("rel", "noopener") node.setAttribute("rel", "noopener")
} else if (node.tagName == "FONT" || node.tagName == "SPAN") {
const color = node.getAttribute("data-mx-color")
const bgColor = node.getAttribute("data-mx-bg-color")
if (color) node.style.color = color;
if (bgColor) node.style.backgroundColor = bgColor;
} }
return node return node
}) })
function sanitize(html) { function sanitize(html) {
return purifier.sanitize(html, DOMPURIFY_CONFIG) return purifier.sanitize(html)
} }
const DOMPURIFY_CONFIG = {
ALLOWED_URI_REGEXP: /^mxc:\/\/[a-zA-Z0-9\.]+\/[a-zA-Z0-9]+$/, // As per the spec we only allow mxc uris
ALLOWED_TAGS: ['font', 'del', 'h1', 'h2', 'h3', 'h4', 'h5', 'h6', 'blockquote', 'p', 'a', 'ul', 'ol', 'sup', 'sub', 'li', 'b', 'i', 'u', 'strong', 'em', 'strike', 'code', 'hr', 'br', 'div', 'table', 'thead', 'tbody', 'tr', 'th', 'td', 'caption', 'pre', 'span', 'img'],
};
class HTMLMessage extends Event { class HTMLMessage extends Event {
render() { render() {