fix: harden OpenVINO doc triage prototype

openvino-doc-image-triage-npu/server.py

@@ -13,6 +13,7 @@ configured allowed roots. It never uploads document/image contents externally.
 from __future__ import annotations
 
 import argparse
+import ipaddress
 import json
 import os
 from http.server import BaseHTTPRequestHandler, ThreadingHTTPServer
@@ -23,6 +24,19 @@ from urllib.parse import urlparse
 from triage import DEFAULT_EMBED_URL, TriageOptions, read_npu_busy, triage_batch, triage_file
 
 
+def _validate_loopback_host(host: str) -> str:
+    """Reject non-loopback binds; this prototype is never a LAN service."""
+    normalized = host.strip()
+    if normalized == "localhost":
+        return normalized
+    try:
+        if ipaddress.ip_address(normalized).is_loopback:
+            return normalized
+    except ValueError:
+        pass
+    raise ValueError("host must be localhost/loopback for this prototype")
+
+
 def _roots_within_configured(requested_roots: list[Any], configured_roots: list[Path]) -> list[Path]:
     """Return request roots only when they narrow the startup allowlist."""
     narrowed: list[Path] = []
@@ -166,10 +180,14 @@ def main() -> int:
     parser.add_argument("--port", type=int, default=int(os.environ.get("DOC_IMAGE_TRIAGE_PORT", "18829")))
     parser.add_argument("--allowed-root", action="append", default=[], help="allowed local root; may repeat")
     args = parser.parse_args()
+    try:
+        host = _validate_loopback_host(args.host)
+    except ValueError as exc:
+        parser.error(str(exc))
     roots = [Path(p).expanduser().resolve() for p in args.allowed_root] or [Path.cwd().resolve()]
-    httpd = ThreadingHTTPServer((args.host, args.port), Handler)
+    httpd = ThreadingHTTPServer((host, args.port), Handler)
     httpd.allowed_roots = roots  # type: ignore[attr-defined]
-    print(json.dumps({"service": "openvino-doc-image-triage-npu", "host": args.host, "port": args.port, "allowed_roots": [str(p) for p in roots]}), flush=True)
+    print(json.dumps({"service": "openvino-doc-image-triage-npu", "host": host, "port": args.port, "allowed_roots": [str(p) for p in roots]}), flush=True)
     httpd.serve_forever()
     return 0