Updated script that can be controled by Nodejs web app

lib/python3.13/site-packages/dns/asyncbackend.py

@@ -0,0 +1,101 @@
+# Copyright (C) Dnspython Contributors, see LICENSE for text of ISC license
+
+from typing import Dict
+
+import dns.exception
+
+# pylint: disable=unused-import
+from dns._asyncbackend import (  # noqa: F401  lgtm[py/unused-import]
+    Backend,
+    DatagramSocket,
+    Socket,
+    StreamSocket,
+)
+
+# pylint: enable=unused-import
+
+_default_backend = None
+
+_backends: Dict[str, Backend] = {}
+
+# Allow sniffio import to be disabled for testing purposes
+_no_sniffio = False
+
+
+class AsyncLibraryNotFoundError(dns.exception.DNSException):
+    pass
+
+
+def get_backend(name: str) -> Backend:
+    """Get the specified asynchronous backend.
+
+    *name*, a ``str``, the name of the backend.  Currently the "trio"
+    and "asyncio" backends are available.
+
+    Raises NotImplementedError if an unknown backend name is specified.
+    """
+    # pylint: disable=import-outside-toplevel,redefined-outer-name
+    backend = _backends.get(name)
+    if backend:
+        return backend
+    if name == "trio":
+        import dns._trio_backend
+
+        backend = dns._trio_backend.Backend()
+    elif name == "asyncio":
+        import dns._asyncio_backend
+
+        backend = dns._asyncio_backend.Backend()
+    else:
+        raise NotImplementedError(f"unimplemented async backend {name}")
+    _backends[name] = backend
+    return backend
+
+
+def sniff() -> str:
+    """Attempt to determine the in-use asynchronous I/O library by using
+    the ``sniffio`` module if it is available.
+
+    Returns the name of the library, or raises AsyncLibraryNotFoundError
+    if the library cannot be determined.
+    """
+    # pylint: disable=import-outside-toplevel
+    try:
+        if _no_sniffio:
+            raise ImportError
+        import sniffio
+
+        try:
+            return sniffio.current_async_library()
+        except sniffio.AsyncLibraryNotFoundError:
+            raise AsyncLibraryNotFoundError("sniffio cannot determine async library")
+    except ImportError:
+        import asyncio
+
+        try:
+            asyncio.get_running_loop()
+            return "asyncio"
+        except RuntimeError:
+            raise AsyncLibraryNotFoundError("no async library detected")
+
+
+def get_default_backend() -> Backend:
+    """Get the default backend, initializing it if necessary."""
+    if _default_backend:
+        return _default_backend
+
+    return set_default_backend(sniff())
+
+
+def set_default_backend(name: str) -> Backend:
+    """Set the default backend.
+
+    It's not normally necessary to call this method, as
+    ``get_default_backend()`` will initialize the backend
+    appropriately in many cases.  If ``sniffio`` is not installed, or
+    in testing situations, this function allows the backend to be set
+    explicitly.
+    """
+    global _default_backend
+    _default_backend = get_backend(name)
+    return _default_backend