From ed0425c60abe1b746b1ca5b4039984d2ad6583c4 Mon Sep 17 00:00:00 2001 From: Martin Panter Date: Sun, 5 Jun 2016 06:28:55 +0000 Subject: Issue #24291: Avoid WSGIRequestHandler doing partial writes If the underlying send() method indicates a partial write, such as when the call is interrupted to handle a signal, the server would silently drop the remaining data. Also add deprecated support for SimpleHandler.stdout.write() doing partial writes. --- Doc/library/wsgiref.rst | 3 ++ Lib/test/test_wsgiref.py | 81 +++++++++++++++++++++++++++++++++++++++++++- Lib/wsgiref/handlers.py | 12 ++++++- Lib/wsgiref/simple_server.py | 17 +++++++--- Misc/NEWS | 5 +++ 5 files changed, 111 insertions(+), 7 deletions(-) diff --git a/Doc/library/wsgiref.rst b/Doc/library/wsgiref.rst index d0a8779..3253f48 100644 --- a/Doc/library/wsgiref.rst +++ b/Doc/library/wsgiref.rst @@ -515,6 +515,9 @@ input, output, and error streams. streams are stored in the :attr:`stdin`, :attr:`stdout`, :attr:`stderr`, and :attr:`environ` attributes. + The :meth:`~io.BufferedIOBase.write` method of *stdout* should write + each chunk in full, like :class:`io.BufferedIOBase`. + .. class:: BaseHandler() diff --git a/Lib/test/test_wsgiref.py b/Lib/test/test_wsgiref.py index b7d02e8..61a750c 100644 --- a/Lib/test/test_wsgiref.py +++ b/Lib/test/test_wsgiref.py @@ -1,18 +1,22 @@ from unittest import mock +from test import support +from test.test_httpservers import NoLogRequestHandler from unittest import TestCase from wsgiref.util import setup_testing_defaults from wsgiref.headers import Headers -from wsgiref.handlers import BaseHandler, BaseCGIHandler +from wsgiref.handlers import BaseHandler, BaseCGIHandler, SimpleHandler from wsgiref import util from wsgiref.validate import validator from wsgiref.simple_server import WSGIServer, WSGIRequestHandler from wsgiref.simple_server import make_server +from http.client import HTTPConnection from io import StringIO, BytesIO, BufferedReader from socketserver import BaseServer from platform import python_implementation import os import re +import signal import sys import unittest @@ -245,6 +249,56 @@ class IntegrationTests(TestCase): ], out.splitlines()) + def test_interrupted_write(self): + # BaseHandler._write() and _flush() have to write all data, even if + # it takes multiple send() calls. Test this by interrupting a send() + # call with a Unix signal. + threading = support.import_module("threading") + pthread_kill = support.get_attribute(signal, "pthread_kill") + + def app(environ, start_response): + start_response("200 OK", []) + return [bytes(support.SOCK_MAX_SIZE)] + + class WsgiHandler(NoLogRequestHandler, WSGIRequestHandler): + pass + + server = make_server(support.HOST, 0, app, handler_class=WsgiHandler) + self.addCleanup(server.server_close) + interrupted = threading.Event() + + def signal_handler(signum, frame): + interrupted.set() + + original = signal.signal(signal.SIGUSR1, signal_handler) + self.addCleanup(signal.signal, signal.SIGUSR1, original) + received = None + main_thread = threading.get_ident() + + def run_client(): + http = HTTPConnection(*server.server_address) + http.request("GET", "/") + with http.getresponse() as response: + response.read(100) + # The main thread should now be blocking in a send() system + # call. But in theory, it could get interrupted by other + # signals, and then retried. So keep sending the signal in a + # loop, in case an earlier signal happens to be delivered at + # an inconvenient moment. + while True: + pthread_kill(main_thread, signal.SIGUSR1) + if interrupted.wait(timeout=float(1)): + break + nonlocal received + received = len(response.read()) + http.close() + + background = threading.Thread(target=run_client) + background.start() + server.handle_request() + background.join() + self.assertEqual(received, support.SOCK_MAX_SIZE - 100) + class UtilityTests(TestCase): @@ -701,6 +755,31 @@ class HandlerTests(TestCase): h.run(error_app) self.assertEqual(side_effects['close_called'], True) + def testPartialWrite(self): + written = bytearray() + + class PartialWriter: + def write(self, b): + partial = b[:7] + written.extend(partial) + return len(partial) + + def flush(self): + pass + + environ = {"SERVER_PROTOCOL": "HTTP/1.0"} + h = SimpleHandler(BytesIO(), PartialWriter(), sys.stderr, environ) + msg = "should not do partial writes" + with self.assertWarnsRegex(DeprecationWarning, msg): + h.run(hello_app) + self.assertEqual(b"HTTP/1.0 200 OK\r\n" + b"Content-Type: text/plain\r\n" + b"Date: Mon, 05 Jun 2006 18:49:54 GMT\r\n" + b"Content-Length: 13\r\n" + b"\r\n" + b"Hello, world!", + written) + if __name__ == "__main__": unittest.main() diff --git a/Lib/wsgiref/handlers.py b/Lib/wsgiref/handlers.py index acb3547..f4300b8 100644 --- a/Lib/wsgiref/handlers.py +++ b/Lib/wsgiref/handlers.py @@ -450,7 +450,17 @@ class SimpleHandler(BaseHandler): self.environ.update(self.base_env) def _write(self,data): - self.stdout.write(data) + result = self.stdout.write(data) + if result is None or result == len(data): + return + from warnings import warn + warn("SimpleHandler.stdout.write() should not do partial writes", + DeprecationWarning) + while True: + data = data[result:] + if not data: + break + result = self.stdout.write(data) def _flush(self): self.stdout.flush() diff --git a/Lib/wsgiref/simple_server.py b/Lib/wsgiref/simple_server.py index e396788..7fddbe8 100644 --- a/Lib/wsgiref/simple_server.py +++ b/Lib/wsgiref/simple_server.py @@ -11,6 +11,7 @@ module. See also the BaseHTTPServer module docs for other API information. """ from http.server import BaseHTTPRequestHandler, HTTPServer +from io import BufferedWriter import sys import urllib.parse from wsgiref.handlers import SimpleHandler @@ -126,11 +127,17 @@ class WSGIRequestHandler(BaseHTTPRequestHandler): if not self.parse_request(): # An error code has been sent, just exit return - handler = ServerHandler( - self.rfile, self.wfile, self.get_stderr(), self.get_environ() - ) - handler.request_handler = self # backpointer for logging - handler.run(self.server.get_app()) + # Avoid passing the raw file object wfile, which can do partial + # writes (Issue 24291) + stdout = BufferedWriter(self.wfile) + try: + handler = ServerHandler( + self.rfile, stdout, self.get_stderr(), self.get_environ() + ) + handler.request_handler = self # backpointer for logging + handler.run(self.server.get_app()) + finally: + stdout.detach() diff --git a/Misc/NEWS b/Misc/NEWS index c51072b..5e7d1ed 100644 --- a/Misc/NEWS +++ b/Misc/NEWS @@ -131,6 +131,11 @@ Core and Builtins Library ------- +- Issue #24291: Fix wsgiref.simple_server.WSGIRequestHandler to completely + write data to the client. Previously it could do partial writes and + truncate data. Also, wsgiref.handler.ServerHandler can now handle stdout + doing partial writes, but this is deprecated. + - Issue #26809: Add ``__all__`` to :mod:`string`. Patch by Emanuel Barry. - Issue #26373: subprocess.Popen.communicate now correctly ignores -- cgit v0.12