feat: Basic Auth se moze ukljuciti/iskljuciti iz Web GUI-ja

Panel je dosad znao samo dodavati i brisati htpasswd korisnike, a sama
auth_basic direktiva se mogla dirati jedino rucno u nginx konfiguraciji.

Dodan prekidac po lokaciji — /guacamole/ i /guacadmin/ su odvojeni, pa
se zastita moze skinuti sa samo jedne. Stanje se cita iz konfiguracije,
ne pamti se zasebno, pa GUI uvijek pokazuje ono sto nginx stvarno radi.

Sigurnosne kocnice:
- Nakon izmjene ide nginx -t; ako padne, konfiguracija se vraca na staro
  prije nego se reload uopce dogodi.
- Ne moze se ukljuciti zastita ako nema nijednog htpasswd korisnika —
  to bi zakljucalo sve.
- Ne moze se obrisati zadnji korisnik dok je Basic Auth aktivan. Ta rupa
  je postojala i prije: brisanje zadnjeg korisnika ostavljalo je prazan
  htpasswd uz aktivan auth_basic, sto zakljuca i Guacamole i sam panel.

Parsiranje ide po location bloku s brojanjem viticastih zagrada, ne
regexom preko cijele datoteke, da se ne pogodi kriva lokacija.

Provjereno na zivoj instalaciji: iskljucenje na /guacamole/ daje 200 bez
prijave dok /guacadmin/ ostaje na 401; ponovno ukljucenje vraca 401 i
konfiguracija je bajt-identicna originalu.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

webgui/app.py

@@ -129,6 +129,73 @@ def htpasswd_users():
     with open(HTPASSWD) as f:
         return [line.split(':')[0] for line in f if ':' in line]
 
+# ── Basic Auth prekidac ───────────────────────────────────────────────────────
+
+# Lokacije kojima se Basic Auth moze zasebno ukljuciti/iskljuciti.
+BASICAUTH_LOCATIONS = {
+    '/guacamole/': 'Guacamole',
+    '/guacadmin/': 'Web GUI',
+}
+
+_AUTH_LINE = re.compile(
+    r'^(?P<indent>[ \t]*)(?P<off>#[ \t]*)?'
+    r'(?P<directive>auth_basic(?:_user_file)?[ \t]+[^\n]*)$'
+)
+
+
+def _location_span(txt, location):
+    """Vraca (start, end) tijela location bloka, ili None ako ga nema."""
+    m = re.search(r'^[ \t]*location[ \t]+' + re.escape(location) + r'[ \t]*\{',
+                  txt, re.MULTILINE)
+    if not m:
+        return None
+    depth, i = 1, m.end()
+    while i < len(txt) and depth:
+        if txt[i] == '{':
+            depth += 1
+        elif txt[i] == '}':
+            depth -= 1
+        i += 1
+    return (m.end(), i - 1)
+
+
+def basicauth_state(txt=None):
+    """Po lokaciji: True aktivan, False zakomentiran, None nema direktive."""
+    if txt is None:
+        conf = get_nginx_conf()
+        if not conf:
+            return {loc: None for loc in BASICAUTH_LOCATIONS}
+        with open(conf) as f:
+            txt = f.read()
+    state = {}
+    for loc in BASICAUTH_LOCATIONS:
+        span = _location_span(txt, loc)
+        if not span:
+            state[loc] = None
+            continue
+        body = txt[span[0]:span[1]]
+        found = [m for m in (_AUTH_LINE.match(l) for l in body.split('\n')) if m]
+        state[loc] = None if not found else not any(m.group('off') for m in found)
+    return state
+
+
+def set_basicauth(txt, location, enabled):
+    span = _location_span(txt, location)
+    if not span:
+        raise ValueError('Lokacija %s nije pronadena u nginx konfiguraciji' % location)
+    head, body, tail = txt[:span[0]], txt[span[0]:span[1]], txt[span[1]:]
+    out = []
+    for line in body.split('\n'):
+        m = _AUTH_LINE.match(line)
+        if m:
+            if enabled:
+                line = m.group('indent') + m.group('directive')
+            elif not m.group('off'):
+                line = m.group('indent') + '# ' + m.group('directive')
+        out.append(line)
+    return head + '\n'.join(out) + tail
+
+
 def ssl_active():
     conf = get_nginx_conf()
     if conf and os.path.exists(conf):
@@ -192,7 +259,9 @@ def dashboard():
 @app.route('/basicauth')
 @login_required
 def basicauth():
-    return render_template('basicauth.html', users=htpasswd_users())
+    return render_template('basicauth.html', users=htpasswd_users(),
+                           auth_state=basicauth_state(),
+                           auth_locations=BASICAUTH_LOCATIONS)
 
 @app.route('/geoip')
 @login_required
@@ -300,11 +369,57 @@ def api_ba_update():
 @api_auth
 def api_ba_delete():
     user = request.json.get('username', '').strip()
+    # Prazan htpasswd uz aktivan auth_basic znaci da nitko vise ne moze
+    # proci — ni kroz Guacamole ni kroz ovaj panel. Vadilo bi se preko SSH-a.
+    remaining = [u for u in htpasswd_users() if u != user]
+    if not remaining and any(basicauth_state().values()):
+        return jsonify(ok=False, msg='Ovo je zadnji korisnik, a Basic Auth je '
+                                     'jos aktivan — prvo ga iskljucite')
     ok, out = run(['htpasswd', '-D', HTPASSWD, user])
     if ok:
         nginx_reload()
     return jsonify(ok=ok, msg=out or 'Korisnik uklonjen')
 
+@app.route('/api/basicauth/toggle', methods=['POST'])
+@api_auth
+def api_ba_toggle():
+    location = request.json.get('location', '')
+    enabled  = bool(request.json.get('enabled'))
+    if location not in BASICAUTH_LOCATIONS:
+        return jsonify(ok=False, msg='Nepoznata lokacija')
+
+    conf = get_nginx_conf()
+    if not conf:
+        return jsonify(ok=False, msg='Nginx konfiguracija nije pronadena')
+
+    if enabled and not htpasswd_users():
+        return jsonify(ok=False, msg='Nema nijednog korisnika — prvo dodajte '
+                                     'korisnika, inace nitko ne moze proci')
+
+    with open(conf) as f:
+        original = f.read()
+    try:
+        updated = set_basicauth(original, location, enabled)
+    except ValueError as e:
+        return jsonify(ok=False, msg=str(e))
+
+    with open(conf, 'w') as f:
+        f.write(updated)
+
+    # Ako nginx odbije novu konfiguraciju, vrati staru da server ostane ziv.
+    ok, out = nginx_reload()
+    if not ok:
+        with open(conf, 'w') as f:
+            f.write(original)
+        return jsonify(ok=False, msg='Nginx je odbio konfiguraciju, vraceno '
+                                     'na staro: ' + out)
+
+    what = BASICAUTH_LOCATIONS[location]
+    return jsonify(ok=True, state=basicauth_state(),
+                   msg='Basic Auth %s za %s' %
+                       ('ukljucen' if enabled else 'iskljucen', what))
+
+
 # ── API – GeoIP ───────────────────────────────────────────────────────────────
 
 def _write_geoip_conf(countries):

webgui/templates/basicauth.html

@@ -4,6 +4,40 @@
 {% block content %}
 <h4 class="mb-4"><i class="bi bi-person-lock me-2"></i>Basic Auth korisnici</h4>
 
+<div class="card mb-4">
+  <div class="card-header fw-semibold">
+    <i class="bi bi-shield-lock me-1"></i> Basic Auth zaštita
+  </div>
+  <div class="card-body">
+    {% for loc, label in auth_locations.items() %}
+    <div class="d-flex justify-content-between align-items-center
+                {% if not loop.last %}mb-3 pb-3 border-bottom{% endif %}"
+         style="border-color:#30363d !important">
+      <div>
+        <div class="fw-semibold">{{ label }}</div>
+        <small class="text-muted"><code>{{ loc }}</code></small>
+      </div>
+      <div class="form-check form-switch mb-0">
+        {% if auth_state[loc] is none %}
+          <span class="badge bg-secondary">nije konfiguriran</span>
+        {% else %}
+        <input class="form-check-input" type="checkbox" role="switch"
+               id="sw-{{ loop.index }}" {% if auth_state[loc] %}checked{% endif %}
+               onchange="toggleAuth('{{ loc }}', this)">
+        {% endif %}
+      </div>
+    </div>
+    {% endfor %}
+    <div class="alert alert-warning mt-3 mb-0 py-2 small">
+      <i class="bi bi-exclamation-triangle me-1"></i>
+      Isključite li zaštitu, na toj lokaciji nestaje prvi sloj obrane i
+      <strong>fail2ban jail <code>nginx-basicauth</code> ostaje bez posla</strong>.
+      Za <code>/guacadmin/</code> to znači da je ovaj panel izložen samo
+      s vlastitom prijavom.
+    </div>
+  </div>
+</div>
+
 <div class="row g-4">
   <!-- Lista korisnika -->
   <div class="col-md-5">
@@ -112,6 +146,21 @@ async function updateUser() {
   showToast(r.msg, r.ok);
 }
 
+async function toggleAuth(location, el) {
+  const enabled = el.checked;
+  if (!enabled && !confirm(
+      `Isključiti Basic Auth za ${location}?\n\n` +
+      `Nakon toga se toj lokaciji pristupa bez prompta.`)) {
+    el.checked = true;
+    return;
+  }
+  el.disabled = true;
+  const r = await api('/api/basicauth/toggle', {location, enabled});
+  showToast(r.msg, r.ok);
+  if (!r.ok) el.checked = !enabled;   // odbijeno — vrati prekidac
+  el.disabled = false;
+}
+
 async function deleteUser(username) {
   if (!confirm(`Ukloniti korisnika "${username}"?`)) return;
   const r = await api('/api/basicauth/delete', {username});