ch20: renamed directory

20-executors/getflags/slow_server.py

@@ -0,0 +1,103 @@
+#!/usr/bin/env python3
+
+"""Slow HTTP server class.
+
+This module implements a ThreadingHTTPServer using a custom
+SimpleHTTPRequestHandler subclass that introduces delays to all
+GET responses, and optionally returns errors to a fraction of
+the requests if given the --error_rate command-line argument.
+"""
+
+import contextlib
+import os
+import socket
+import time
+from functools import partial
+from http import server, HTTPStatus
+from http.server import ThreadingHTTPServer, SimpleHTTPRequestHandler
+from random import random, uniform
+
+MIN_DELAY = 0.5  # minimum delay for do_GET (seconds)
+MAX_DELAY = 5.0  # maximum delay for do_GET (seconds)
+
+class SlowHTTPRequestHandler(SimpleHTTPRequestHandler):
+    """SlowHTTPRequestHandler adds delays and errors to test HTTP clients.
+
+    The optional error_rate argument determines how often GET requests
+    receive a 418 status code, "I'm a teapot".
+    If error_rate is .15, there's a 15% probability of each GET request
+    getting that error.
+    When the server believes it is a teapot, it refuses requests to serve files.
+
+    See: https://tools.ietf.org/html/rfc2324#section-2.3.2
+    """
+
+    def __init__(self, *args, error_rate=0.0, **kwargs):
+        self.error_rate = error_rate
+        super().__init__(*args, **kwargs)
+
+    def do_GET(self):
+        """Serve a GET request."""
+        delay = uniform(MIN_DELAY, MAX_DELAY)
+        cc = self.path[-6:-4].upper()
+        print(f'{cc} delay: {delay:0.2}s')
+        time.sleep(delay)
+        if random() < self.error_rate:
+            # HTTPStatus.IM_A_TEAPOT requires Python >= 3.9
+            try:
+                self.send_error(HTTPStatus.IM_A_TEAPOT, "I'm a Teapot")
+            except BrokenPipeError as exc:
+                print(f'{cc} *** BrokenPipeError: client closed')
+        else:
+            f = self.send_head()
+            if f:
+                try:
+                    self.copyfile(f, self.wfile)
+                except BrokenPipeError as exc:
+                    print(f'{cc} *** BrokenPipeError: client closed')
+                finally:
+                    f.close()
+
+# The code in the `if` block below, including comments, was copied
+# and adapted from the `http.server` module of Python 3.9
+# https://github.com/python/cpython/blob/master/Lib/http/server.py
+
+if __name__ == '__main__':
+    import argparse
+
+    parser = argparse.ArgumentParser()
+    parser.add_argument('--bind', '-b', metavar='ADDRESS',
+                        help='Specify alternate bind address '
+                             '[default: all interfaces]')
+    parser.add_argument('--directory', '-d', default=os.getcwd(),
+                        help='Specify alternative directory '
+                             '[default:current directory]')
+    parser.add_argument('--error-rate', '-e', metavar='PROBABILITY',
+                        default=0.0, type=float,
+                        help='Error rate; e.g. use .25 for 25%% probability '
+                             '[default:0.0]')
+    parser.add_argument('port', action='store',
+                        default=8001, type=int,
+                        nargs='?',
+                        help='Specify alternate port [default: 8001]')
+    args = parser.parse_args()
+    handler_class = partial(SlowHTTPRequestHandler,
+                            directory=args.directory,
+                            error_rate=args.error_rate)
+
+    # ensure dual-stack is not disabled; ref #38907
+    class DualStackServer(ThreadingHTTPServer):
+        def server_bind(self):
+            # suppress exception when protocol is IPv4
+            with contextlib.suppress(Exception):
+                self.socket.setsockopt(
+                    socket.IPPROTO_IPV6, socket.IPV6_V6ONLY, 0)
+            return super().server_bind()
+
+    # test is a top-level function in http.server omitted from __all__
+    server.test(  # type: ignore
+        HandlerClass=handler_class,
+        ServerClass=DualStackServer,
+        port=args.port,
+        bind=args.bind,
+    )