FIX: 11 bugs bảo mật/ổn định (static mount chặn dotfile, delete traversal, cleanup giữ clips serverFileId, upload whitelist, password strength, auth audio endpoints, pedalboard==0.9.19, vendor CDN local) + FEATURE: Carla bridge preview/export MIDI notes âm VSTi (POST /midi-render, /carla-play-notes, nút Preview VSTi/Export MIDI->Audio; pedalboard 0.9.19 raw MIDI bytes; SONICFORGE_STORAGE_DIR cô lập test storage)

app/api/v1/ai_proxy.py

@@ -74,6 +74,8 @@ async def _resolve_host_ips(hostname: str):
 
 
 async def _validate_target_url(url: str, user_id: str):
+    """Validate target. Trả IP đã validate (str) để proxy connect thẳng vào đó
+    chống DNS rebinding TOCTOU; None khi giữ hostname (loopback / https)."""
     parsed = urlparse(url)
     if parsed.scheme not in ("http", "https"):
         raise HTTPException(status_code=400, detail="URL chỉ hỗ trợ giao thức http/https")
@@ -88,7 +90,7 @@ async def _validate_target_url(url: str, user_id: str):
     # Hostname-level fast path for loopback hosts
     if hostname in _LOOPBACK_HOSTS:
         if hostname in allowed_hosts:
-            return
+            return None
         raise HTTPException(status_code=403, detail="Target nội bộ không nằm trong danh sách AI provider đã cấu hình")
 
     # Try direct IP parse (hostname may itself be an IP)
@@ -109,18 +111,34 @@ async def _validate_target_url(url: str, user_id: str):
                 continue
             raise HTTPException(status_code=403, detail="Target IP nội bộ không nằm trong danh sách AI provider đã cấu hình")
 
+    # Trả IP đầu tiên đã validate — http sẽ connect thẳng vào IP này (bind),
+    # không cho httpx re-resolve hostname (fix DNS rebinding TOCTOU).
+    return str(ips[0])
+
 
 @router.post("/proxy")
 async def proxy_llm(req: ProxyRequest, current_user: dict = Depends(get_current_user)):
-    await _validate_target_url(req.url, current_user["user_id"])
+    target_ip = await _validate_target_url(req.url, current_user["user_id"])
     # Never forward the app's own auth token upstream.
     headers = {
         k: v for k, v in req.headers.items()
         if k.lower() not in ("host", "origin", "referer", "x-auth-token")
     }
+    url = req.url
+    # Bug #6: http + hostname (không phải IP literal) → connect thẳng IP đã
+    # validate, giữ Host gốc. https giữ hostname (SNI + cert validation chống
+    # rebinding sẵn). IPv6 skip (netloc bracket phức tạp, hiếm gặp).
+    if target_ip and ":" not in target_ip:
+        parsed = urlparse(req.url)
+        if parsed.scheme == "http":
+            host_header = parsed.netloc
+            new_netloc = parsed.netloc.replace(parsed.hostname, target_ip)
+            from urllib.parse import urlunsplit
+            url = urlunsplit((parsed.scheme, new_netloc, parsed.path, parsed.query, parsed.fragment))
+            headers["Host"] = host_header
     try:
         async with httpx.AsyncClient(timeout=180.0, follow_redirects=False) as client:
-            resp = await client.post(req.url, headers=headers, json=req.body)
+            resp = await client.post(url, headers=headers, json=req.body)
             raw = resp.text
             try:
                 return resp.json()