Xmlrpc: accept data:str|bytes and require method:str (python#12734)

Declared <https://github.com/python/cpython/blob/main/Lib/xmlrpc/server.py#L622>

Inside
[`do_POST()`](https://github.com/python/cpython/blob/main/Lib/xmlrpc/server.py#L493)
`data: bytes`, where `decode_request_content()` only handles `gzip`
compression.
The `result` is then written to `self.wfile`, which uses `bytes`.

But for
[CGI](https://github.com/python/cpython/blob/main/Lib/xmlrpc/server.py#L636)
`str` is used: [`handle_xmlrpc(self,
request_text)`](https://github.com/python/cpython/blob/main/Lib/xmlrpc/server.py#L642)
calls the argument `request_text`, which is read from `sys.stdin` as
type `str` and then passed to `_marshaled_dispatch()`, which internally calls
[`xmlrpc.client.loads()`](https://github.com/python/cpython/blob/main/Lib/xmlrpc/server.py#L257)
to parse the XML using Expat, which accepts both `str` and `bytes`; the
later defaults to encoding `utf-8`, but other encodings can be
used when explicitly specified:

>>> xmlrpc.client.loads('<params><param><value><string>ä</string></value></param></params>')
(('ä',), None)
>>> xmlrpc.client.loads('<params><param><value><string>ä</string></value></param></params>'.encode("utf-8"))
(('ä',), None)
>>> xmlrpc.client.loads('<params><param><value><string>ä</string></value></param></params>'.encode("iso-8859-1"))
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python3.11/xmlrpc/client.py", line 1029, in loads
    p.feed(data)
  File "/usr/lib/python3.11/xmlrpc/client.py", line 451, in feed
    self._parser.Parse(data, False)
xml.parsers.expat.ExpatError: not well-formed (invalid token): line 3, column 15
>>> xmlrpc.client.loads('<?xml version="1.0" encoding="utf-8"?><params><param><value><string>ä</string></value></param></params>'.encode("iso-8859-1"))
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python3.11/xmlrpc/client.py", line 1029, in loads
    p.feed(data)
  File "/usr/lib/python3.11/xmlrpc/client.py", line 451, in feed
    self._parser.Parse(data, False)
xml.parsers.expat.ExpatError: not well-formed (invalid token): line 1, column 68
>>> xmlrpc.client.loads('<?xml version="1.0" encoding="iso-8859-1"?><params><param><value><string>ä</string></value></param></params>'.encode("iso-8859-1"))
(('ä',), None)

Signed-off-by: Philipp Hahn <[email protected]>
Reviewed-By: Jelle Zijlstra <[email protected]>

stdlib/xmlrpc/client.pyi

@@ -200,7 +200,7 @@ def dumps(
     allow_none: bool = False,
 ) -> str: ...
 def loads(
-    data: str, use_datetime: bool = False, use_builtin_types: bool = False
+    data: str | ReadableBuffer, use_datetime: bool = False, use_builtin_types: bool = False
 ) -> tuple[tuple[_Marshallable, ...], str | None]: ...
 def gzip_encode(data: ReadableBuffer) -> bytes: ...  # undocumented
 def gzip_decode(data: ReadableBuffer, max_decode: int = 20971520) -> bytes: ...  # undocumented

stdlib/xmlrpc/server.pyi

@@ -1,6 +1,7 @@
 import http.server
 import pydoc
 import socketserver
+from _typeshed import ReadableBuffer
 from collections.abc import Callable, Iterable, Mapping
 from re import Pattern
 from typing import Any, ClassVar, Protocol
@@ -48,8 +49,8 @@ class SimpleXMLRPCDispatcher:  # undocumented
     def register_multicall_functions(self) -> None: ...
     def _marshaled_dispatch(
         self,
-        data: str,
-        dispatch_method: Callable[[str | None, tuple[_Marshallable, ...]], Fault | tuple[_Marshallable, ...]] | None = None,
+        data: str | ReadableBuffer,
+        dispatch_method: Callable[[str, tuple[_Marshallable, ...]], Fault | tuple[_Marshallable, ...]] | None = None,
         path: Any | None = None,
     ) -> str: ...  # undocumented
     def system_listMethods(self) -> list[str]: ...  # undocumented