feat: use built in dompurify

conf/tsconfig.content_scripts.json

@@ -16,7 +16,7 @@
     "outDir": "../build/_/content_scripts",
     "baseUrl": "../extension",
     "paths": {
-      "dompurify": ["types/purify.d.ts"],
+      "dompurify": ["../node_modules/dompurify/dist/purify.cjs.d.ts"],
       "openpgp": ["../node_modules/openpgp/openpgp.d.ts"],
       "@openpgp/web-stream-tools": ["../node_modules/@openpgp/web-stream-tools/lib/index.d.ts"],
       "squire-rte": ["../node_modules/squire-rte/dist/types/Squire.d.ts"],

extension/chrome/elements/compose-modules/compose-send-btn-module.ts

@@ -179,7 +179,7 @@ export class ComposeSendBtnModule extends ViewModule<ComposeView> {
         return;
       }
       if ('src' in node) {
-        const img: Element = node;
+        const img = node as HTMLImageElement;
         // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
         const src = img.getAttribute('src')!;
         const { mimeType, data } = this.parseInlineImageSrc(src);

extension/js/common/message-renderer.ts

@@ -83,28 +83,28 @@ export class MessageRenderer {
     const inlineCIDAttachments = new Set<Attachment>();
 
     // Define the hook function for DOMPurify to process image elements after sanitizing attributes
-    const processImageElements = (node: Element | null) => {
-      // Ensure the node exists and has a 'src' attribute
-      if (!node || !('src' in node)) return;
-      const imageSrc = node.getAttribute('src');
+    DOMPurify.addHook('afterSanitizeAttributes', currentNode => {
+      // Ensure the node is an Element
+      if (!(currentNode instanceof Element)) return;
+
+      // Check if the node has a 'src' attribute
+      const imageSrc = currentNode.getAttribute('src');
       if (!imageSrc) return;
+
       const matches = imageSrc.match(CID_PATTERN);
 
-      // Check if the src attribute contains a CID
+      // If the src attribute contains a CID
       if (matches?.[1]) {
         const contentId = matches[1];
         const contentIdAttachment = attachments.find(attachment => attachment.cid === `<${contentId}>`);
 
         // Replace the src attribute with a base64 encoded string
         if (contentIdAttachment) {
           inlineCIDAttachments.add(contentIdAttachment);
-          node.setAttribute('src', `data:${contentIdAttachment.type};base64,${contentIdAttachment.getData().toBase64Str()}`);
+          currentNode.setAttribute('src', `data:${contentIdAttachment.type};base64,${contentIdAttachment.getData().toBase64Str()}`);
         }
       }
-    };
-
-    // Add the DOMPurify hook
-    DOMPurify.addHook('afterSanitizeAttributes', processImageElements);
+    });
 
     // Sanitize the HTML and remove the DOMPurify hooks
     const sanitizedHtml = Xss.htmlSanitize(html);

extension/js/common/platform/xss.ts

@@ -107,44 +107,56 @@ export class Xss {
     // used whenever untrusted remote content (eg html email) is rendered, but we still want to preserve html
     DOMPurify.removeAllHooks();
     DOMPurify.addHook('afterSanitizeAttributes', node => {
-      if (!node) {
+      // Ensure the node is an Element
+      if (!(node instanceof Element)) {
         return;
       }
-      if ('style' in node) {
+
+      // Handle style attributes
+      if (node.hasAttribute('style')) {
         // mitigation rather than a fix, which will involve updating CSP, see https://github.com/FlowCrypt/flowcrypt-browser/issues/2648
-        const style = (node as Element).getAttribute('style')?.toLowerCase();
+        const style = node.getAttribute('style')?.toLowerCase();
         if (style && (style.includes('url(') || style.includes('@import'))) {
-          (node as Element).removeAttribute('style'); // don't want any leaks through css url()
+          node.removeAttribute('style'); // don't want any leaks through css url()
         }
         // strip css styles that could use to overlap with the extension UI
         if (style && Xss.FORBID_CSS_STYLE.test(style)) {
           const updatedStyle = style.replace(Xss.FORBID_CSS_STYLE, '');
-          (node as HTMLElement).setAttribute('style', updatedStyle);
+          node.setAttribute('style', updatedStyle);
         }
       }
-      if ('src' in node) {
-        const img = node as HTMLImageElement;
+
+      // Handle image attributes
+      if (node.tagName === 'IMG') {
+        const img = node as HTMLImageElement; // Narrow type to HTMLImageElement
         const src = img.getAttribute('src');
         if (imgHandling === 'IMG-DEL') {
           img.remove(); // just skip images
         } else if (!src) {
           img.remove(); // src that exists but is null is suspicious
         } else if (imgHandling === 'IMG-KEEP' && checkValidURL(src)) {
           // replace remote image with remote_image_container
-          const remoteImgEl = `<div class="remote_image_container" data-src="${src}" data-test="remote-image-container"><span>Authenticity of this remote image cannot be verified.</span></div>`;
+          const remoteImgEl = `
+        <div class="remote_image_container" data-src="${src}" data-test="remote-image-container">
+          <span>Authenticity of this remote image cannot be verified.</span>
+        </div>`;
           Xss.replaceElementDANGEROUSLY(img, remoteImgEl); // xss-safe-value
         }
       }
+
+      // Handle custom containers or CID-patterned src
       if ((node.classList.contains('remote_image_container') || CID_PATTERN.test(node.getAttribute('src') ?? '')) && imgHandling === 'IMG-TO-PLAIN-TEXT') {
-        Xss.replaceElementDANGEROUSLY(node, node.getAttribute('data-src') ?? node.getAttribute('alt') ?? ''); // xss-safe-value
+        const replacement = node.getAttribute('data-src') ?? node.getAttribute('alt') ?? '';
+        Xss.replaceElementDANGEROUSLY(node, replacement); // xss-safe-value
       }
-      if ('target' in node) {
-        // open links in new window
-        (node as Element).setAttribute('target', '_blank');
-        // prevents https://www.owasp.org/index.php/Reverse_Tabnabbing
-        (node as Element).setAttribute('rel', 'noopener noreferrer');
+
+      // Handle links (target and rel attributes)
+      if (node.tagName === 'A') {
+        node.setAttribute('target', '_blank'); // prevents https://www.owasp.org/index.php/Reverse_Tabnabbing
+        node.setAttribute('rel', 'noopener noreferrer');
       }
     });
+
     const cleanHtml = Xss.htmlSanitize(dirtyHtml, true);
     DOMPurify.removeAllHooks();
     return cleanHtml;

extension/types/trusted-types.d.ts

@@ -1,3 +1,7 @@
 interface Window {
   trustedTypes: any;
-}
+}
+
+interface TrustedHTML  {}
+
+interface TrustedTypePolicy {}

package.json

@@ -10,7 +10,6 @@
     "@types/chai": "4.3.19",
     "@types/chai-as-promised": "7.1.8",
     "@types/chrome": "0.0.284",
-    "@types/dompurify": "3.2.0",
     "@types/jquery": "3.5.32",
     "@types/mailparser": "3.4.5",
     "ava": "5.3.1",

tsconfig.json

@@ -24,7 +24,7 @@
       "pdfjs": ["lib/pdf.min.mjs", "types/pdf.js.d.ts"],
       "squire-rte": ["../node_modules/squire-rte/dist/types/Squire.d.ts"],
       "@openpgp/web-stream-tools": ["../node_modules/@openpgp/web-stream-tools/lib/index.d.ts", "lib/streams/streams.js"],
-      "dompurify": ["types/purify.d.ts", "lib/purify.js", "COMMENT"],
+      "dompurify": ["../node_modules/dompurify/dist/purify.cjs.d.ts", "lib/purify.js", "COMMENT"],
       "fine-uploader": ["lib/fine-uploader.js", "COMMENT"],
       "clipboard": ["lib/clipboard.js", "COMMENT"],
       "filesize": ["lib/filesize.js", "COMMENT"],