fix(endpoints): normalize URL handling (#4338)

src/model_context.py

@@ -17,10 +17,11 @@ import httpx
 logger = logging.getLogger(__name__)
 
 _LOCAL_HOSTS = {"localhost", "127.0.0.1", "0.0.0.0", "::1", "host.docker.internal"}
-_PRIVATE_PREFIXES = ("10.", "172.16.", "172.17.", "172.18.", "172.19.",
-                     "172.20.", "172.21.", "172.22.", "172.23.", "172.24.",
-                     "172.25.", "172.26.", "172.27.", "172.28.", "172.29.",
-                     "172.30.", "172.31.", "192.168.")
+_PRIVATE_NETWORKS = (
+    ipaddress.ip_network("10.0.0.0/8"),
+    ipaddress.ip_network("172.16.0.0/12"),
+    ipaddress.ip_network("192.168.0.0/16"),
+)
 
 # Tailscale uses the CGNAT range 100.64.0.0/10, NOT all of 100.0.0.0/8.
 # A bare "100." prefix would classify public addresses (e.g. AWS ranges
@@ -36,6 +37,14 @@ def _in_tailscale_range(host: str) -> bool:
         return False
 
 
+def _is_private_ip_literal(host: str) -> bool:
+    try:
+        ip = ipaddress.ip_address(host)
+    except ValueError:
+        return False
+    return any(ip in network for network in _PRIVATE_NETWORKS)
+
+
 def _normalize_base_for_compare(url: str) -> str:
     url = (url or "").strip().rstrip("/")
     for suffix in ("/chat/completions", "/models", "/completions", "/v1/messages"):
@@ -87,7 +96,7 @@ def is_local_endpoint(url: str) -> bool:
         return True
     try:
         host = urlparse(url).hostname or ""
-        return host in _LOCAL_HOSTS or host.startswith(_PRIVATE_PREFIXES) or _in_tailscale_range(host)
+        return host in _LOCAL_HOSTS or _is_private_ip_literal(host) or _in_tailscale_range(host)
     except Exception:
         return False