security(layout): SSRF guard on /layout/import-brand (reject internal hosts, no redirects)

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

app/layout_routes.py

@@ -10,6 +10,7 @@ from sqlalchemy import text
 
 from .auth import require_token
 from .db import get_db
+from .urlguard import safe_public_url
 
 # Storefront customizer — per-store theme + header menu + which elements appear on cards /
 # product pages, in what order. Lets RecordGod dress ANY shop without touching code.
@@ -71,7 +72,12 @@ async def import_brand(body: UrlIn, ident=Depends(require_token)):
     if not url.startswith("http"):
         url = "https://" + url
     try:
-        async with httpx.AsyncClient(timeout=15, follow_redirects=True,
+        url = safe_public_url(url)
+    except ValueError as e:
+        raise HTTPException(400, f"refused url: {e}")
+    # ponytail: DNS-rebinding TOCTOU remains; follow_redirects=False closes the redirect bypass
+    try:
+        async with httpx.AsyncClient(timeout=15, follow_redirects=False,
                                      headers={"User-Agent": "RecordGod/0.1 brand-import"}) as c:
             html = (await c.get(url)).text
     except Exception as e:

app/urlguard.py

@@ -0,0 +1,16 @@
+import ipaddress
+import socket
+from urllib.parse import urlparse
+
+
+def safe_public_url(url):
+    """Resolve url's host and reject any that maps to a non-public IP (SSRF guard)."""
+    p = urlparse(url)
+    if p.scheme not in ("http", "https") or not p.hostname:
+        raise ValueError("url must be http(s) with a hostname")
+    for info in socket.getaddrinfo(p.hostname, None):
+        ip = ipaddress.ip_address(info[4][0])
+        if (ip.is_private or ip.is_loopback or ip.is_link_local or ip.is_reserved
+                or ip.is_multicast or ip.is_unspecified):
+            raise ValueError(f"host resolves to non-public ip {ip}")
+    return url