fix: allow local mcp urls with pinned dns

nanobot/agent/tools/mcp.py

@@ -180,7 +180,7 @@ async def _probe_http_url(url: str, timeout: float = 3.0) -> bool:
     port = parsed.port
     if not port:
         port = 443 if parsed.scheme == "https" else 80
-    ok, _, resolved_ips = resolve_url_target(url)
+    ok, _, resolved_ips = resolve_url_target(url, allow_loopback=True)
     if not ok:
         return False
     try:
@@ -218,7 +218,7 @@ def _redact_url(url: str) -> str:
 
 async def _validate_mcp_request_url(request: httpx.Request) -> None:
     """Validate each outgoing MCP HTTP request, including redirect targets."""
-    ok, error = validate_url_target(str(request.url))
+    ok, error = validate_url_target(str(request.url), allow_loopback=True)
     if not ok:
         raise httpx.RequestError(
             f"Blocked unsafe MCP URL {_redact_url(str(request.url))} ({error})",
@@ -885,7 +885,7 @@ async def connect_mcp_servers(
                         follow_redirects=True,
                         timeout=timeout,
                         auth=auth,
-                        transport=PinnedDNSAsyncTransport(),
+                        transport=PinnedDNSAsyncTransport(allow_loopback=True),
                     )
 
                 read, write = await server_stack.enter_async_context(
@@ -903,7 +903,7 @@ async def connect_mcp_servers(
                         event_hooks={"request": [_validate_mcp_request_url]},
                         follow_redirects=True,
                         timeout=httpx.Timeout(30.0, connect=10.0),
-                        transport=PinnedDNSAsyncTransport(),
+                        transport=PinnedDNSAsyncTransport(allow_loopback=True),
                     )
                 )
                 read, write, _ = await server_stack.enter_async_context(

nanobot/security/network.py

@@ -149,12 +149,13 @@ def pin_resolved_url_dns(url: str, resolved_ips: tuple[str, ...]):
 class PinnedDNSAsyncTransport(httpx.AsyncBaseTransport):
     """HTTPX transport that pins each request to the IPs validated for its URL."""
 
-    def __init__(self) -> None:
+    def __init__(self, *, allow_loopback: bool = False) -> None:
+        self._allow_loopback = allow_loopback
         self._inner = httpx.AsyncHTTPTransport()
 
     async def handle_async_request(self, request: httpx.Request) -> httpx.Response:
         url = str(request.url)
-        ok, error, resolved_ips = resolve_url_target(url)
+        ok, error, resolved_ips = resolve_url_target(url, allow_loopback=self._allow_loopback)
         if not ok:
             raise httpx.RequestError(error, request=request)
         with pin_resolved_url_dns(url, resolved_ips):

tests/tools/test_mcp_tool.py

@@ -712,8 +712,8 @@ async def test_connect_mcp_servers_logs_stdio_pollution_hint(
 @pytest.mark.parametrize(
     "config",
     [
-        MCPServerConfig(url="http://127.0.0.1:9/sse"),
-        MCPServerConfig(type="streamableHttp", url="http://127.0.0.1:9/mcp"),
+        MCPServerConfig(url="http://169.254.169.254/sse"),
+        MCPServerConfig(type="streamableHttp", url="http://169.254.169.254/mcp"),
     ],
 )
 async def test_connect_mcp_servers_rejects_unsafe_http_urls_before_probe(
@@ -762,7 +762,7 @@ async def test_connect_mcp_servers_http_clients_reject_unsafe_redirect_targets(
     sent_urls: list[str] = []
     used_transports: list[str] = []
 
-    def _validate(url: str) -> tuple[bool, str]:
+    def _validate(url: str, **_kwargs: object) -> tuple[bool, str]:
         checked_urls.append(url)
         if url == "http://127.0.0.1/private":
             return False, "loopback blocked"
@@ -804,7 +804,11 @@ async def test_connect_mcp_servers_http_clients_reject_unsafe_redirect_targets(
 
     monkeypatch.setattr(mcp_mod, "validate_url_target", _validate)
     monkeypatch.setattr(mcp_mod, "_probe_http_url", _reachable)
-    monkeypatch.setattr(mcp_mod, "PinnedDNSAsyncTransport", lambda: httpx.MockTransport(_handler))
+    monkeypatch.setattr(
+        mcp_mod,
+        "PinnedDNSAsyncTransport",
+        lambda **_kwargs: httpx.MockTransport(_handler),
+    )
     monkeypatch.setattr(mcp_mod.httpx, "AsyncClient", _async_client_with_mock_transport)
     monkeypatch.setattr(sys.modules["mcp.client.sse"], "sse_client", _fake_sse_client)
     monkeypatch.setattr(