app.js

@@ -121,6 +121,16 @@
   const calcBtnText    = submitBtn?.querySelector('.calc-btn-text');
   const calcBtnLoading = submitBtn?.querySelector('.calc-btn-loading');
 
+  // Mirrors security.js validateEmail — the server is the authority, this just
+  // gives immediate feedback instead of a round-trip.
+  const EMAIL_RX = /^[A-Za-z0-9](?:[A-Za-z0-9._%+-]{0,62}[A-Za-z0-9])?@[A-Za-z0-9](?:[A-Za-z0-9-]{0,61}[A-Za-z0-9])?(?:\.[A-Za-z0-9](?:[A-Za-z0-9-]{0,61}[A-Za-z0-9])?)*\.[A-Za-z]{2,24}$/;
+
+  function isValidEmail(v) {
+    if (v.length > 254 || v.indexOf('@') > 64) return false;
+    if (v.includes('..')) return false;
+    return EMAIL_RX.test(v);
+  }
+
   function showCalcError(msg) {
     if (!calcErr) return;
     calcErr.textContent = msg;
@@ -148,6 +158,14 @@
       showCalcError('Please fill in homesites and annual dues income to continue.');
       return;
     }
+
+    // Email is optional, but anything entered must be a real address.
+    if (calcEmail && !isValidEmail(calcEmail)) {
+      showCalcError('Please enter a valid email address.');
+      document.getElementById('calcEmail')?.focus();
+      return;
+    }
+
     calcErr.classList.add('hidden');
     setCalcLoading(true);
 
@@ -225,9 +243,10 @@
       // is stored. AI/service errors (502/503) fall through to the local result.
       if (!res.ok) {
         const data = await res.json().catch(() => ({}));
-        if (data.blocked) {
+        if (data.blocked || data.field === 'email') {
           setCalcLoading(false);
           showCalcError(data.error || 'We could not verify this submission. Please try again.');
+          if (data.field === 'email') document.getElementById('calcEmail')?.focus();
           resetCaptcha();
           await fetchFormToken();   // tokens are single-use; issue a fresh one
           return;

security.js

@@ -144,10 +144,70 @@ const MESSAGES = {
   captcha_missing:     'Please complete the verification challenge.',
   captcha_failed:      'Verification failed. Please try the challenge again.',
   captcha_unavailable: 'Verification is temporarily unavailable. Please try again in a moment.',
+  email_required:      'Please enter your email address.',
+  email_invalid:       'Please enter a valid email address.',
+  email_too_long:      'That email address is too long.',
 };
 
 const STATUS = { rate_limited: 429, honeypot: 400 };
 
+/** User-facing message for a validation/abuse reason code. */
+function messageFor(reason) {
+  return MESSAGES[reason] || 'Submission rejected.';
+}
+
+// ── Email validation ─────────────────────────────────────
+// Deliberately stricter than RFC 5322. The local part is limited to the
+// characters real-world addresses actually use, which excludes every shell
+// metacharacter (; | & ` $ ( ) < > \ " ' space) and every CSV-injection lead-in
+// (= + @ at position 0). RFC-legal oddities like `foo!bar$baz@x.com` are
+// rejected — an acceptable trade for a marketing form.
+const EMAIL_RX = /^[A-Za-z0-9](?:[A-Za-z0-9._%+-]{0,62}[A-Za-z0-9])?@[A-Za-z0-9](?:[A-Za-z0-9-]{0,61}[A-Za-z0-9])?(?:\.[A-Za-z0-9](?:[A-Za-z0-9-]{0,61}[A-Za-z0-9])?)*\.[A-Za-z]{2,24}$/;
+
+// C0/C1 control characters and DEL — includes the CR/LF used for header injection.
+const CONTROL_CHARS_RX = /[\x00-\x1F\x7F-\x9F]/;
+
+/**
+ * Validate an email address.
+ * Returns { ok: true, email } with the normalised (trimmed, lower-cased) value,
+ * or { ok: false, reason }.
+ *
+ * Pass { required: false } to accept an empty value (the calculator's email
+ * field is optional) — an empty result comes back as { ok: true, email: null }.
+ */
+function validateEmail(raw, { required = true } = {}) {
+  if (raw === undefined || raw === null || raw === '') {
+    return required ? { ok: false, reason: 'email_required' } : { ok: true, email: null };
+  }
+
+  // Anything that isn't a plain string is a structured-injection attempt
+  // (arrays and objects can survive into places a string wouldn't).
+  if (typeof raw !== 'string') return { ok: false, reason: 'email_invalid' };
+
+  const email = raw.trim();
+  if (email === '') {
+    return required ? { ok: false, reason: 'email_required' } : { ok: true, email: null };
+  }
+
+  // Length caps first — bounds every check that follows.
+  if (email.length > 254) return { ok: false, reason: 'email_too_long' };
+
+  // Control characters, including the newlines used for header injection.
+  if (CONTROL_CHARS_RX.test(email)) return { ok: false, reason: 'email_invalid' };
+
+  const at = email.indexOf('@');
+  if (at < 1 || at !== email.lastIndexOf('@')) return { ok: false, reason: 'email_invalid' };
+
+  const local  = email.slice(0, at);
+  const domain = email.slice(at + 1);
+
+  if (local.length > 64 || domain.length > 253) return { ok: false, reason: 'email_too_long' };
+  if (email.includes('..'))                     return { ok: false, reason: 'email_invalid' };
+  if (!EMAIL_RX.test(email))                    return { ok: false, reason: 'email_invalid' };
+
+  return { ok: true, email: email.toLowerCase() };
+}
+
 /**
  * Run every protection layer for a public form POST.
  * Returns { ok: true, ip } or { ok: false, status, error, reason }.
@@ -215,6 +275,8 @@ module.exports = {
   turnstileEnabled,
   issueFormToken,
   guardSubmission,
+  validateEmail,
+  messageFor,
   publicConfig,
   clientIp,
 };

server.js

@@ -129,36 +129,41 @@ app.get('/api/form-token', (_req, res) => {
 app.post('/api/leads', (req, res) => {
   const { firstName, lastName, email, orgName, state, role, unitCount, betaInterest, source } = req.body ?? {};
 
+  // Coerce defensively: a non-string (array, object, number) would otherwise
+  // blow up on .trim() and surface as a 500 instead of a 400.
+  const str = v => (typeof v === 'string' ? v.trim() : '');
+
   // Validate required fields
-  if (!firstName?.trim() || !lastName?.trim() || !email?.trim()) {
+  if (!str(firstName) || !str(lastName) || !str(email)) {
     return res.status(400).json({ error: 'firstName, lastName, and email are required.' });
   }
-  if (!orgName?.trim()) {
+  if (!str(orgName)) {
     return res.status(400).json({ error: 'Organization name is required.' });
   }
-  if (!state?.trim()) {
+  if (!str(state)) {
     return res.status(400).json({ error: 'State is required.' });
   }
 
-  // Simple email format check
-  const emailRx = /^[^\s@]+@[^\s@]+\.[^\s@]+$/;
-  if (!emailRx.test(email.trim())) {
-    return res.status(400).json({ error: 'Invalid email address.' });
+  // Strict email format check — see security.validateEmail
+  const emailCheck = security.validateEmail(email);
+  if (!emailCheck.ok) {
+    return res.status(400).json({ error: security.messageFor(emailCheck.reason), field: 'email' });
   }
+  const cleanEmail = emailCheck.email;
 
   // Check for duplicate
-  const existing = findByEmail.get(email.trim().toLowerCase());
+  const existing = findByEmail.get(cleanEmail);
   if (existing) {
     return res.status(409).json({ error: 'This email is already on the list.', id: existing.id });
   }
 
   try {
     const info = insertLead.run({
-      firstName:    firstName.trim(),
-      lastName:     lastName.trim(),
-      email:        email.trim().toLowerCase(),
-      orgName:      orgName?.trim() ?? null,
-      state:        state?.trim() ?? null,
+      firstName:    str(firstName),
+      lastName:     str(lastName),
+      email:        cleanEmail,
+      orgName:      str(orgName) || null,
+      state:        str(state)   || null,
       role:         role ?? null,
       unitCount:    unitCount ?? null,
       betaInterest: betaInterest ? 1 : 0,
@@ -190,7 +195,7 @@ app.post('/api/calculate', async (req, res) => {
   function saveCalcSubmission(aiRecommendation) {
     try {
       insertCalcSubmission.run({
-        email:           email?.trim() || null,
+        email:           cleanEmail,
         optIn:           optIn ? 1 : 0,
         homesites:       homesites || null,
         propertyType:    propertyType || null,
@@ -220,6 +225,15 @@ app.post('/api/calculate', async (req, res) => {
     email, optIn, totalPotential, opInterest, resInterest,
   } = req.body ?? {};
 
+  // Email is optional here, but if one is supplied it must be a real address.
+  // Nothing is stored or sent onward until it passes.
+  const emailCheck = security.validateEmail(email, { required: false });
+  if (!emailCheck.ok) {
+    console.warn(`[abuse] rejected email from ${guard.ip}: ${JSON.stringify(String(email).slice(0, 120))}`);
+    return res.status(400).json({ error: security.messageFor(emailCheck.reason), field: 'email' });
+  }
+  const cleanEmail = emailCheck.email;
+
   if (!homesites || !annualIncome) {
     return res.status(400).json({ error: 'homesites and annualIncome are required.' });
   }