fix: implement unwrapping of embedded message/rfc822 attachments and enhance HTML body validation

2026-03-18 17:32:25 +01:00
parent cdc521b693
commit 2edbf379e2
1 changed files with 146 additions and 13 deletions
@@ -390,6 +390,21 @@ function extractNestedSignedDataCandidate(
  };
 }

+/**
+ * Check if an HTML body string is effectively empty (just boilerplate/whitespace).
+ * Outlook often generates HTML bodies with Word CSS + &nbsp; but no real text.
+ */
+function isHtmlBodyEffectivelyEmpty(html: string): boolean {
+  const textContent = html
+    .replace(/<style[^>]*>[\s\S]*?<\/style>/gi, '')
+    .replace(/<[^>]+>/g, '')
+    .replace(/&nbsp;/gi, ' ')
+    .replace(/&#160;/g, ' ')
+    .replace(/\s+/g, '')
+    .trim();
+  return textContent.length === 0;
+}
+
 function extractMimePartContent(rawText: string, depth = 0): { html: string | null; text: string | null } {
  if (depth > 6) {
    const trimmed = rawText.trim();
@@ -871,6 +886,12 @@ export function EmailViewer({
  const [tnefText, setTnefText] = useState<string | null>(null);
  const [tnefAttachments, setTnefAttachments] = useState<TnefAttachment[]>([]);

+  // Embedded message/rfc822 unwrapping (Outlook forward-as-attachment)
+  const [embeddedEmailHtml, setEmbeddedEmailHtml] = useState<string | null>(null);
+  const [embeddedEmailText, setEmbeddedEmailText] = useState<string | null>(null);
+  const [embeddedEmailAttachments, setEmbeddedEmailAttachments] = useState<PostalMimeAttachment[]>([]);
+  const [embeddedEmailUnwrapped, setEmbeddedEmailUnwrapped] = useState(false);
+
  // Ensure S/MIME key records are loaded from IndexedDB
  useLayoutEffect(() => {
    smimeStore.load();
@@ -1088,6 +1109,10 @@ export function EmailViewer({
    setTnefHtml(null);
    setTnefText(null);
    setTnefAttachments([]);
+    setEmbeddedEmailHtml(null);
+    setEmbeddedEmailText(null);
+    setEmbeddedEmailAttachments([]);
+    setEmbeddedEmailUnwrapped(false);
  }, [email?.id, externalContentPolicy]);

  const prepareSmimeUnlock = useCallback((keyRecordId: string) => {
@@ -1675,15 +1700,20 @@ export function EmailViewer({
    debug.group('TNEF Processing');
    debug.log('Found TNEF attachment:', tnefAtt.name, 'type:', tnefAtt.type, 'blobId:', tnefAtt.blobId, 'size:', tnefAtt.size);

-    // Check if the email already has a usable HTML body
-    const hasHtmlBody = !!(
-      email.htmlBody?.[0]?.partId &&
-      email.bodyValues?.[email.htmlBody[0].partId]?.value?.trim()
-    );
-    if (hasHtmlBody) {
-      debug.log('TNEF: Email already has HTML body, will extract attachments only');
+    // Check if the email already has a usable HTML body with real content
+    // Outlook often forwards TNEF emails with an HTML body that's just Word
+    // boilerplate (CSS + &nbsp;) — treat these as effectively empty.
+    const htmlPartId = email.htmlBody?.[0]?.partId;
+    const htmlValue = htmlPartId ? email.bodyValues?.[htmlPartId]?.value?.trim() : '';
+    let hasRealHtmlBody = !!htmlValue;
+    if (hasRealHtmlBody && htmlValue && isHtmlBodyEffectivelyEmpty(htmlValue)) {
+      hasRealHtmlBody = false;
+      debug.log('TNEF: Email HTML body is effectively empty (only boilerplate/whitespace), treating as no body');
+    }
+    if (hasRealHtmlBody) {
+      debug.log('TNEF: Email has real HTML body, will extract attachments only');
    } else {
-      debug.log('TNEF: Email has no HTML body, proceeding with full TNEF extraction');
+      debug.log('TNEF: Email has no usable HTML body, proceeding with full TNEF extraction');
    }

    let cancelled = false;
@@ -1719,10 +1749,10 @@ export function EmailViewer({

        debug.log('TNEF parse result — htmlBody:', !!parsed.htmlBody, '(' + (parsed.htmlBody?.length ?? 0) + ' chars)', ', body:', !!parsed.body, '(' + (parsed.body?.length ?? 0) + ' chars)', ', attachments:', parsed.attachments.length);

-        if (parsed.htmlBody && !hasHtmlBody) {
+        if (parsed.htmlBody && !hasRealHtmlBody) {
          setTnefHtml(parsed.htmlBody);
        }
-        if (parsed.body && !hasHtmlBody) {
+        if (parsed.body && !hasRealHtmlBody) {
          setTnefText(parsed.body);
        }
        if (parsed.attachments.length > 0) {
@@ -1746,6 +1776,83 @@ export function EmailViewer({
    return () => { cancelled = true; };
  }, [email, client]);

+  // Embedded message/rfc822 unwrapping
+  // When Outlook forwards an email as an attachment, the outer email body is
+  // often empty Word boilerplate and the real content is inside a message/rfc822
+  // attachment. Detect this pattern and unwrap the embedded email.
+  useEffect(() => {
+    if (!email?.attachments || !client) return;
+
+    // Find message/rfc822 attachment
+    const rfc822Att = email.attachments.find(
+      att => att.type === 'message/rfc822' && att.blobId
+    );
+    if (!rfc822Att?.blobId) return;
+
+    // Only unwrap if the outer body is effectively empty
+    const htmlPartId = email.htmlBody?.[0]?.partId;
+    const htmlValue = htmlPartId ? email.bodyValues?.[htmlPartId]?.value?.trim() : '';
+    const textPartId = email.textBody?.[0]?.partId;
+    const textValue = textPartId ? email.bodyValues?.[textPartId]?.value?.trim() : '';
+
+    const hasRealHtml = !!htmlValue && !isHtmlBodyEffectivelyEmpty(htmlValue);
+    const hasRealText = !!textValue;
+
+    if (hasRealHtml || hasRealText) {
+      debug.log('Embedded RFC822: Outer email has real body content, not unwrapping');
+      return;
+    }
+
+    debug.group('Embedded RFC822 Unwrapping');
+    debug.log('Found message/rfc822 attachment:', rfc822Att.name, 'blobId:', rfc822Att.blobId, 'size:', rfc822Att.size);
+    debug.log('Outer email body is empty, will unwrap embedded email');
+
+    let cancelled = false;
+
+    async function unwrapEmbedded() {
+      try {
+        const blobBytes = await client!.fetchBlobArrayBuffer(rfc822Att!.blobId!);
+        if (cancelled) { debug.groupEnd(); return; }
+        if (blobBytes.byteLength === 0) {
+          debug.warn('Embedded RFC822: Fetched blob is empty');
+          debug.groupEnd();
+          return;
+        }
+
+        const { default: PostalMime } = await import('postal-mime');
+        const parser = new PostalMime();
+        const parsed = await parser.parse(new Uint8Array(blobBytes));
+        if (cancelled) { debug.groupEnd(); return; }
+
+        debug.log('Embedded RFC822 parsed — html:', !!parsed.html, '(' + (parsed.html?.length ?? 0) + ' chars)',
+          ', text:', !!parsed.text, '(' + (parsed.text?.length ?? 0) + ' chars)',
+          ', attachments:', parsed.attachments?.length ?? 0);
+
+        if (parsed.html) {
+          setEmbeddedEmailHtml(parsed.html);
+        }
+        if (parsed.text) {
+          setEmbeddedEmailText(parsed.text);
+        }
+        if (parsed.attachments && parsed.attachments.length > 0) {
+          setEmbeddedEmailAttachments(parsed.attachments as PostalMimeAttachment[]);
+          debug.log('Embedded RFC822 attachments:', parsed.attachments.map(
+            a => (a.filename || 'unnamed') + ' (' + a.mimeType + ')'
+          ).join(', '));
+        }
+        setEmbeddedEmailUnwrapped(true);
+        debug.groupEnd();
+      } catch (err) {
+        debug.error('Embedded RFC822 unwrapping failed:', err);
+        debug.groupEnd();
+      }
+    }
+
+    unwrapEmbedded();
+
+    return () => { cancelled = true; };
+  }, [email, client]);
+
  // Fetch inline CID images with authentication to prevent browser auth dialogs
  useEffect(() => {
    let cancelled = false;
@@ -1829,6 +1936,8 @@ export function EmailViewer({
    const jmapAttachments = (email?.attachments ?? [])
      // Hide winmail.dat when we have successfully extracted TNEF content or attachments
      .filter(att => !(tnefHtml || tnefText || tnefAttachments.length > 0) || !isTnefAttachment(att.name, att.type))
+      // Hide message/rfc822 when we have unwrapped the embedded email
+      .filter(att => !embeddedEmailUnwrapped || att.type !== 'message/rfc822')
      .map((attachment, index) => ({
        id: attachment.blobId || `${attachment.name || 'attachment'}-${index}`,
        name: attachment.name || null,
@@ -1847,8 +1956,19 @@ export function EmailViewer({
      tnefData: att.data,
    }));

-    return [...jmapAttachments, ...tnefExtracted];
-  }, [email?.attachments, smimeDecryptedAttachments, tnefHtml, tnefText, tnefAttachments]);
+    // Append attachments extracted from embedded message/rfc822
+    const embeddedExtracted: EffectiveAttachment[] = embeddedEmailAttachments
+      .filter(att => !att.contentId) // Skip inline CID images
+      .map((att, index) => ({
+        id: `embedded-${index}-${att.filename || att.mimeType}`,
+        name: att.filename || null,
+        type: att.mimeType || 'application/octet-stream',
+        size: getPostalMimeAttachmentSize(att),
+        decryptedAttachment: att,
+      }));
+
+    return [...jmapAttachments, ...tnefExtracted, ...embeddedExtracted];
+  }, [email?.attachments, smimeDecryptedAttachments, tnefHtml, tnefText, tnefAttachments, embeddedEmailUnwrapped, embeddedEmailAttachments]);

  // Generate email source for viewing
  const generateEmailSource = (email: Email): string => {
@@ -2189,8 +2309,21 @@ export function EmailViewer({
        .replace(/(https?:\/\/[^\s<]+)/g, '<a href="$1" target="_blank" rel="noopener noreferrer">$1</a>');
      return { html: htmlFromText, isHtml: false };
    }
+    // Embedded message/rfc822 unwrapped content
+    if (embeddedEmailHtml) {
+      const cleanHtml = DOMPurify.sanitize(embeddedEmailHtml, EMAIL_SANITIZE_CONFIG);
+      return { html: cleanHtml, isHtml: true };
+    }
+    if (embeddedEmailText) {
+      const htmlFromText = embeddedEmailText
+        .replace(/&/g, '&amp;')
+        .replace(/</g, '&lt;')
+        .replace(/>/g, '&gt;')
+        .replace(/(https?:\/\/[^\s<]+)/g, '<a href="$1" target="_blank" rel="noopener noreferrer">$1</a>');
+      return { html: htmlFromText, isHtml: false };
+    }
    return emailContent;
-  }, [cidBlobUrls, emailContent, smimeDecryptedHtml, smimeDecryptedText, tnefHtml, tnefText]);
+  }, [cidBlobUrls, emailContent, smimeDecryptedHtml, smimeDecryptedText, tnefHtml, tnefText, embeddedEmailHtml, embeddedEmailText]);

  const handleEffectiveAttachmentOpen = useCallback((attachment: EffectiveAttachment) => {
    const isPreviewable = isFilePreviewable(attachment.name || undefined, attachment.type);