Treat smartcam 500 errors after handshake as retryable (#1395)

`smartcam` devices can respond with 500 if another session is created from the same host

kasa/httpclient.py

@@ -113,10 +113,23 @@ class HttpClient:
                 ssl=ssl,
             )
             async with resp:
-                if resp.status == 200:
-                    response_data = await resp.read()
-                    if return_json:
+                response_data = await resp.read()
+
+            if resp.status == 200:
+                if return_json:
+                    response_data = json_loads(response_data.decode())
+            else:
+                _LOGGER.debug(
+                    "Device %s received status code %s with response %s",
+                    self._config.host,
+                    resp.status,
+                    str(response_data),
+                )
+                if response_data and return_json:
+                    try:
                         response_data = json_loads(response_data.decode())
+                    except Exception:
+                        _LOGGER.debug("Device %s response could not be parsed as json")
 
         except (aiohttp.ServerDisconnectedError, aiohttp.ClientOSError) as ex:
             if not self._wait_between_requests:

kasa/transports/sslaestransport.py

@@ -8,6 +8,7 @@ import hashlib
 import logging
 import secrets
 import ssl
+from contextlib import suppress
 from enum import Enum, auto
 from typing import TYPE_CHECKING, Any, cast
 
@@ -229,6 +230,31 @@ class SslAesTransport(BaseTransport):
             ssl=await self._get_ssl_context(),
         )
 
+        if TYPE_CHECKING:
+            assert self._encryption_session is not None
+
+        # Devices can respond with 500 if another session is created from
+        # the same host. Decryption may not succeed after that
+        if status_code == 500:
+            msg = (
+                f"Device {self._host} replied with status 500 after handshake, "
+                f"response: "
+            )
+            decrypted = None
+            if isinstance(resp_dict, dict) and (
+                response := resp_dict.get("result", {}).get("response")
+            ):
+                with suppress(Exception):
+                    decrypted = self._encryption_session.decrypt(response.encode())
+
+            if decrypted:
+                msg += decrypted
+            else:
+                msg += str(resp_dict)
+
+            _LOGGER.debug(msg)
+            raise _RetryableError(msg)
+
         if status_code != 200:
             raise KasaException(
                 f"{self._host} responded with an unexpected "
@@ -241,7 +267,6 @@ class SslAesTransport(BaseTransport):
 
         if TYPE_CHECKING:
             resp_dict = cast(dict[str, Any], resp_dict)
-            assert self._encryption_session is not None
 
         if "result" in resp_dict and "response" in resp_dict["result"]:
             raw_response: str = resp_dict["result"]["response"]

tests/transports/test_sslaestransport.py

@@ -18,6 +18,7 @@ from kasa.exceptions import (
     DeviceError,
     KasaException,
     SmartErrorCode,
+    _RetryableError,
 )
 from kasa.httpclient import HttpClient
 from kasa.transports.aestransport import AesEncyptionSession
@@ -217,6 +218,48 @@ async def test_device_blocked_response(mocker):
         await transport.perform_handshake()
 
 
+@pytest.mark.parametrize(
+    ("response", "expected_msg"),
+    [
+        pytest.param(
+            {"error_code": -1, "msg": "Check tapo tag failed"},
+            '{"error_code": -1, "msg": "Check tapo tag failed"}',
+            id="can-decrypt",
+        ),
+        pytest.param(
+            b"12345678",
+            str({"result": {"response": "12345678"}, "error_code": 0}),
+            id="cannot-decrypt",
+        ),
+    ],
+)
+async def test_device_500_error(mocker, response, expected_msg):
+    """Test 500 error raises retryable exception."""
+    host = "127.0.0.1"
+    mock_ssl_aes_device = MockSslAesDevice(host)
+    mocker.patch.object(
+        aiohttp.ClientSession, "post", side_effect=mock_ssl_aes_device.post
+    )
+
+    transport = SslAesTransport(
+        config=DeviceConfig(host, credentials=Credentials(MOCK_USER, MOCK_PWD))
+    )
+
+    request = {
+        "method": "getDeviceInfo",
+        "params": None,
+    }
+
+    await transport.perform_handshake()
+
+    mock_ssl_aes_device.put_next_response(response)
+    mock_ssl_aes_device.status_code = 500
+
+    msg = f"Device 127.0.0.1 replied with status 500 after handshake, response: {expected_msg}"
+    with pytest.raises(_RetryableError, match=msg):
+        await transport.send(json_dumps(request))
+
+
 async def test_port_override():
     """Test that port override sets the app_url."""
     host = "127.0.0.1"
@@ -302,6 +345,8 @@ class MockSslAesDevice:
         self.digest_password_fail = digest_password_fail
         self.device_blocked = device_blocked
 
+        self._next_responses: list[dict | bytes] = []
+
     async def post(self, url: URL, params=None, json=None, data=None, *_, **__):
         if data:
             json = json_loads(data)
@@ -386,11 +431,24 @@ class MockSslAesDevice:
         assert self.encryption_session
         decrypted_request = self.encryption_session.decrypt(encrypted_request.encode())
         decrypted_request_dict = json_loads(decrypted_request)
-        decrypted_response = await self._post(url, decrypted_request_dict)
-        async with decrypted_response:
-            decrypted_response_data = await decrypted_response.read()
 
-        encrypted_response = self.encryption_session.encrypt(decrypted_response_data)
+        if self._next_responses:
+            next_response = self._next_responses.pop(0)
+            if isinstance(next_response, dict):
+                decrypted_response_data = json_dumps(next_response).encode()
+                encrypted_response = self.encryption_session.encrypt(
+                    decrypted_response_data
+                )
+            else:
+                encrypted_response = next_response
+        else:
+            decrypted_response = await self._post(url, decrypted_request_dict)
+            async with decrypted_response:
+                decrypted_response_data = await decrypted_response.read()
+            encrypted_response = self.encryption_session.encrypt(
+                decrypted_response_data
+            )
+
         response = (
             decrypted_response_data
             if self.do_not_encrypt_response
@@ -405,3 +463,6 @@ class MockSslAesDevice:
     async def _return_send_response(self, url: URL, json: dict[str, Any]):
         result = {"result": {"method": None}, "error_code": self.send_error_code}
         return self._mock_response(self.status_code, result)
+
+    def put_next_response(self, request: dict | bytes) -> None:
+        self._next_responses.append(request)