python · jfrost-mo · Dec 23, 2022 · Dec 23, 2022 · Dec 23, 2022
diff --git a/Doc/library/http.server.rst b/Doc/library/http.server.rst
@@ -376,13 +376,16 @@ provides three different variants:
       :func:`os.listdir` to scan the directory, and returns a ``404`` error
       response if the :func:`~os.listdir` fails.
 
-      If the request was mapped to a file, it is opened. Any :exc:`OSError`
-      exception in opening the requested file is mapped to a ``404``,
-      ``'File not found'`` error. If there was a ``'If-Modified-Since'``
-      header in the request, and the file was not modified after this time,
-      a ``304``, ``'Not Modified'`` response is sent. Otherwise, the content
-      type is guessed by calling the :meth:`guess_type` method, which in turn
-      uses the *extensions_map* variable, and the file contents are returned.
+      If the request was mapped to a file, it is opened. If the file does not
+      exist, and the URL does not contain an extension, the path is instead
+      checked for the file with the additional extension ``.html`` or ``.htm``
+      (in that order) and that is opened. Any :exc:`OSError` exception in
+      opening the requested file is mapped to a ``404``, ``'File not found'``
+      error. If there was a ``'If-Modified-Since'`` header in the request, and
+      the file was not modified after this time, a ``304``, ``'Not Modified'``
+      response is sent. Otherwise, the content type is guessed by calling the
+      :meth:`guess_type` method, which in turn uses the *extensions_map*
+      variable, and the file contents are returned.
 
       A ``'Content-type:'`` header with the guessed content type is output,
       followed by a ``'Content-Length:'`` header with the file's size and a
@@ -398,6 +401,9 @@ provides three different variants:
       .. versionchanged:: 3.7
          Support of the ``'If-Modified-Since'`` header.
 
+      .. versionchanged:: 3.12
+         Checks for presence of HTML file in absence of an extension.
+
 The :class:`SimpleHTTPRequestHandler` class can be used in the following
 manner in order to create a very basic webserver serving files relative to
 the current directory::

diff --git a/Lib/http/server.py b/Lib/http/server.py
@@ -653,6 +653,7 @@ class SimpleHTTPRequestHandler(BaseHTTPRequestHandler):
     """
 
     index_pages = ["index.html", "index.htm"]
+    default_extensions = [".html", ".htm"]
     server_version = "SimpleHTTP/" + __version__
     extensions_map = _encodings_map_default = {
         '.gz': 'application/gzip',
@@ -661,11 +662,14 @@ class SimpleHTTPRequestHandler(BaseHTTPRequestHandler):
         '.xz': 'application/x-xz',
     }
 
-    def __init__(self, *args, directory=None, index_pages=None, **kwargs):
+    def __init__(self, *args, directory=None, index_pages=None,
+        default_extensions=None, **kwargs):
         if directory is None:
             directory = os.getcwd()
         if index_pages is not None:
             self.index_pages = index_pages
+        if default_extensions is not None:
+            self.default_extensions = default_extensions
         self.directory = os.fspath(directory)
         super().__init__(*args, **kwargs)
 
@@ -725,6 +729,13 @@ def send_head(self):
         if path.endswith("/"):
             self.send_error(HTTPStatus.NOT_FOUND, "File not found")
             return None
+        # Special case for URLs with default extension.
+        if os.path.splitext(path)[1] == "":
+            if not os.path.exists(path):
+                for extension in self.default_extensions:
+                    if os.path.exists(path + extension):
+                        path += extension
+                        break
         try:
             f = open(path, 'rb')
         except OSError:

diff --git a/Lib/test/test_httpservers.py b/Lib/test/test_httpservers.py
@@ -587,6 +587,21 @@ def test_path_without_leading_slash(self):
         self.assertEqual(response.getheader("Location"),
                          self.tempdir_name + "/?hi=1")
 
+    def test_default_extension(self):
+        """Checks an extensionless path finds a HMTL file, and finds an
+        extensionless file with priority.
+        """
+        data1 = b"SPAM SPAM SPAM!\r\n"
+        with open(os.path.join(self.tempdir_name, 'spam.html'), 'wb') as f:
+            f.write(data1)
+        response = self.request(self.tempdir_name + '/spam')
+        self.check_status_and_reason(response, HTTPStatus.OK, data1)
+        data2 = b"The one true spam.\r\n"
+        with open(os.path.join(self.tempdir_name, 'spam'), 'wb') as f:
+            f.write(data2)
+        response = self.request(self.tempdir_name + '/spam')
+        self.check_status_and_reason(response, HTTPStatus.OK, data2)
+
     def test_html_escape_filename(self):
         filename = '<test&>.txt'
         fullpath = os.path.join(self.tempdir, filename)