app: make direct HTTP json request function consistent with qrexec

the behavior of the HTTP and qrexec JSON request methods must
be the same in terms of which exceptions are raised when

sdclientapi/__init__.py

@@ -40,11 +40,11 @@ def __init__(self) -> None:
 
 class ServerConnectionError(Exception):
     """
-    Error raised if a request times out.
+    Error raised if we cannot connect to the server.
     """
 
     def __init__(self) -> None:
-        super().__init__("The request timed out.")
+        super().__init__("Cannot connect to the server.")
 
 
 def json_query(proxy_vm_name: str, data: str, timeout: Optional[int] = None) -> str:
@@ -166,6 +166,9 @@ def _send_http_json_request(
         except (TooManyRedirects, ConnectionError):
             raise ServerConnectionError
 
+        if result.status_code == http.HTTPStatus.FORBIDDEN:
+            raise AuthError("forbidden")
+
         # Because when we download a file there is no JSON in the body
         if path_query.endswith("/download"):
             return result, result.status_code, dict(result.headers)
@@ -201,12 +204,13 @@ def _send_rpc_json_request(
             raise RequestTimeoutError
         elif "error" in data and result["status"] == http.HTTPStatus.BAD_GATEWAY:
             raise ServerConnectionError
-        elif "error" in data and result["status"] == 403:
+        elif "error" in data and result["status"] == http.HTTPStatus.FORBIDDEN:
             raise AuthError(data["error"])
-        elif "error" in data and result["status"] != 404:
+        elif "error" in data and result["status"] != http.HTTPStatus.NOT_FOUND:
             # We exclude 404 since if we encounter a 404, it means that an
             # item is missing. In that case we return to the caller to
-            # handle that with an appropriate message.
+            # handle that with an appropriate message. However, if the error
+            # is not a 404, then we raise.
             raise BaseError(data["error"])
 
         return data, result["status"], result["headers"]