package-lock.json

@@ -2412,6 +2412,11 @@
       "integrity": "sha512-F/1DnUGPopORZi0ni+CvrCgHQ5FyEAHRLSApuYWMmrbSwoN2Mn/7k+Gl38gJnR7yyDZk6WLXwiGod1JOWNDKGw==",
       "dev": true
     },
+    "highlight.js": {
+      "version": "10.3.1",
+      "resolved": "https://registry.npmjs.org/highlight.js/-/highlight.js-10.3.1.tgz",
+      "integrity": "sha512-jeW8rdPdhshYKObedYg5XGbpVgb1/DT4AHvDFXhkU7UnGSIjy9kkJ7zHG7qplhFHMitTSzh5/iClKQk3Kb2RFQ=="
+    },
     "hmac-drbg": {
       "version": "1.0.1",
       "resolved": "https://registry.npmjs.org/hmac-drbg/-/hmac-drbg-1.0.1.tgz",

package.json

@@ -12,7 +12,8 @@
   "author": "",
   "license": "AGPL-3.0-only",
   "dependencies": {
-    "dompurify": "^2.2.0"
+    "dompurify": "^2.2.0",
+    "highlight.js": "^10.3.1"
   },
   "devDependencies": {
     "@babel/core": "^7.11.1",

src/js/events/components.js

@@ -0,0 +1,11 @@
+const {ElemJS} = require("../basic")
+const hljs = require("highlight.js")
+
+class HighlightedCode extends ElemJS {
+	constructor(code) {
+		super(code)
+		hljs.highlightBlock(this.element)
+	}
+}
+
+module.exports = {HighlightedCode}

src/js/events/event.js

@@ -44,7 +44,9 @@ class MatrixEvent extends ElemJS {
 		if (this.editedAt) {
 			this.child(ejs("span").class("c-message__edited").text("(edited)").attribute("title", "at " + dateFormatter.format(this.editedAt)))
 		}
+		return this
 	}
+
 	static canRender(_event) {
 		return false
 	}

src/js/events/message.js

@@ -1,21 +1,17 @@
-const {ejs} = require("../basic")
+const {ejs, ElemJS} = require("../basic")
+const hljs = require("highlight.js")
+const {HighlightedCode} = require("./components")
 const DOMPurify = require("dompurify")
 const {resolveMxc} = require("../functions")
 const {MatrixEvent} = require("./event")
 
 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'],
+purifier.addHook("uponSanitizeAttribute", (node, hookevent, config) => {
+	//If purifier already rejected an attribute there is no point in checking it
+	if (hookevent.keepAttr === false) return;
 
-	// 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: {
+	const allowedElementAttributes = {
 		"FONT": ["data-mx-bg-color", "data-mx-color", "color"],
 		"SPAN": ["data-mx-bg-color", "data-mx-color", "color"],
 		"A": ["name", "target", "href"],
@@ -23,58 +19,73 @@ purifier.setConfig({
 		"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] || []
+	const allowed_attributes = allowedElementAttributes[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) => {
-	if (node.tagName == "IMG") {
-		let src = node.getAttribute("src")
-		if (src) src = resolveMxc(src)
-
-		node.setAttribute("src", src)
-	} else if (node.tagName == "A") {
+	if (node.tagName == "CODE") {
+		node.classList.forEach(c => {
+			if (!c.startsWith("language-")) {
+				node.classList.remove(c)
+			}
+		})
+	}
+	if (node.tagName == "A") {
 		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
 })
 
+function cleanHTML(html) {
+	const 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'],
 
-function sanitize(html) {
+		// In case we mess up in the uponSanitizeAttribute hook
+		ALLOWED_ATTR: ["data-mx-bg-color", "data-mx-color", "color",
+			"name", "target", "href",
+			"width", "height", "alt", "title", "src", "data-mx-emoticon",
+			"start", "class"],
+	}
 	return purifier.sanitize(html)
 }
 
+//Here we put all the processing of the messages that isn't as likely to potentially lead to security issues
+function postProcessElements(rootNode) {
+	const element = rootNode.element
+	element.querySelectorAll("code").forEach((n) => rootNode.child(new HighlightedCode(n)))
+
+	element.querySelectorAll("img").forEach((n) => {
+		let src = n.getAttribute("src")
+		if (src) src = resolveMxc(src)
+		n.setAttribute("src", src)
+	})
+	element.querySelectorAll("font, span").forEach((n) => {
+		const color = n.getAttribute("data-mx-color") || n.getAttribute("color")
+		const bgColor = n.getAttribute("data-mx-bg-color")
+		if (color) n.style.color = color;
+		if (bgColor) n.style.backgroundColor = bgColor;
+	})
+}
+
+
 class HTMLMessage extends MatrixEvent {
 	render() {
-		super.render()
+		this.clearChildren()
+
 		let html = this.data.content.formatted_body
 		const content = ejs("div")
-		html = sanitize(html)
+
+		html = cleanHTML(html)
 		content.html(html)
+		postProcessElements(content)
+
 		this.child(content)
+
+		super.render()
 	}
 
 	static canRender(event) {
@@ -91,8 +102,8 @@ class HTMLMessage extends MatrixEvent {
 
 class TextMessage extends MatrixEvent {
 	render() {
-		super.render()
-		return this.text(this.data.content.body)
+		this.text(this.data.content.body)
+		return super.render()
 	}
 
 	static canRender(event) {

src/sass/components/highlighted-code.sass

@@ -0,0 +1 @@
+@use "../../../node_modules/highlight.js/scss/obsidian"

src/sass/main.sass

@@ -5,4 +5,5 @@
 @use "./components/chat"
 @use "./components/chat-input"
 @use "./components/anchor"
+@use "./components/highlighted-code"
 @use "./loading"