fix(security): quoted local-part email mask — strip delimiter quotes, split on last @ (DC-109) [glm-grade=A]

dashcaddy-api/__tests__/logging-email-masking-dc095.test.js

@@ -242,7 +242,9 @@ describe('DC-095 round 2: adversarial judge findings', () => {
     const out = consoleOut();
     expect(out).not.toContain('john doe');
     expect(out).not.toContain('"john doe"@example.com');
-    expect(out).toContain('****@example.com');
+    // DC-109: delimiter quotes are syntax, not PII — strip, never re-emit.
+    expect(out).toContain('jo****@example.com'); // 2 REAL local chars, canonical shape
+    expect(out).not.toMatch(/["']j\*{4}/); // old bug: stray quote among the 2 chars
   });
 
   test('class instance enumerable email prop masked, prototype preserved', () => {

dashcaddy-api/__tests__/redact-log-pii.test.js

@@ -177,3 +177,37 @@ describe('DC-098 redact-log-pii.js end-to-end', () => {
     expect(stderr).toContain('error:');
   });
 });
+
+describe('DC-109 quoted local-part mask edge (maskEmailAddress)', () => {
+  test('quoted local-part: quotes stripped, 2 REAL chars kept, no stray quote', () => {
+    expect(maskEmailAddress('"john doe"@example.com')).toBe('jo****@example.com');
+    expect(maskEmailAddress('"a"@example.com')).toBe('a****@example.com');
+    expect(maskEmailAddress('ab"cd@e.f"@example.com')).toBe('ab****@example.com'); // mixed, no strip
+  });
+
+  test('quoted local-part containing "@" splits on LAST @ (real domain boundary)', () => {
+    expect(maskEmailAddress('"a@b"@example.com')).toBe('a@****@example.com');
+  });
+
+  test('empty quoted local-part masks to bare ****@domain', () => {
+    expect(maskEmailAddress('""@example.com')).toBe('****@example.com');
+  });
+
+  test('plain addresses unchanged by DC-109 (canonical shape preserved)', () => {
+    expect(maskEmailAddress('sami@example.com')).toBe('sa****@example.com');
+    expect(maskEmailAddress('ab@x.io')).toBe('a****@x.io');
+    expect(maskEmailAddress('a@x.io')).toBe('a****@x.io');
+  });
+
+  test('masked quoted output cannot re-match EMAIL_RE (idempotence on splice line)', () => {
+    const line = 'contact "john.doe@x"@example.com or root@web-1 ok';
+    const masked = maskEmailsInString(line);
+    const re = new RegExp(EMAIL_RE.source, EMAIL_RE.flags);
+    // After one pass nothing that still contains the original address OR a
+    // fresh matchable email-shaped token may remain.
+    expect(masked).not.toContain('john.doe');
+    expect(re.test(masked)).toBe(false);
+    const twice = maskEmailsInString(masked);
+    expect(twice).toBe(masked); // fully idempotent
+  });
+});

dashcaddy-api/src/utils/logging.js

@@ -85,9 +85,20 @@ function formatTime() {
 const EMAIL_RE = /(?:[A-Za-z0-9._%+-]{1,64}|"[^"\n\\]{1,64}")@[A-Za-z0-9.-]{0,253}\.[A-Za-z]{2,24}/g;
 
 function maskEmailAddress(addr) {
-  const at = addr.indexOf('@');
-  const local = addr.slice(0, at);
+  // addr is always a full EMAIL_RE match. Quoted local-parts (RFC 5322) match
+  // WITH their delimiter quotes and may contain '@' inside the quotes, so
+  // split on the LAST '@' (the real domain boundary), never the first.
+  // The quotes are syntax, not PII: strip them before masking and never
+  // re-emit them — slice(0, 2) of '"john doe"@…' used to leave a stray
+  // unbalanced quote in the output that could glue onto later text and
+  // re-match EMAIL_RE on a second pass (DC-109).
+  const at = addr.lastIndexOf('@');
+  let local = addr.slice(0, at);
   const domain = addr.slice(at);
+  if (local.length >= 2 && local.startsWith('"') && local.endsWith('"')) {
+    local = local.slice(1, -1);
+  }
+  if (local.length === 0) return '****' + domain;
   if (local.length <= 2) return local[0] + '****' + domain;
   return local.slice(0, 2) + '****' + domain;
 }