New submission from Vlad <vladandje...@gmail.com>:
When dealing with a new connection, SocketServer.BaseRequestHandler.__init__
first calls the request handler (self.handle below) and then calls cleanup code
which closes the connection (self.finish below).
class BaseRequestHandler:
def __init__(self, request, client_address, server):
< ... snip ... >
try:
self.handle()
finally:
self.finish()
The issue arises when a client disconnects suddenly during the self.handle()
call. The handler may attempt to write data to the disconnected socket. This
will cause an exception (which is correct), but somehow data will still be
added to the connection's buffer and self.wfile.closed will be False! As a
result, BaseRequestHandler.finish() will attempt to flush the connection's
buffer and this will raise another exception which can't be handled without
modifying the library code.
----------------------------------------
Exception happened during processing of request from ('127.0.0.1', 62718)
Traceback (most recent call last):
File "C:\Python27\lib\SocketServer.py", line 284, in _handle_request_noblock
self.process_request(request, client_address)
File "C:\Python27\lib\SocketServer.py", line 310, in process_request
self.finish_request(request, client_address)
File "C:\Python27\lib\SocketServer.py", line 323, in finish_request
self.RequestHandlerClass(request, client_address, self)
File "C:\Python27\lib\SocketServer.py", line 641, in __init__
self.finish()
File "C:\Python27\lib\SocketServer.py", line 694, in finish
self.wfile.flush()
File "C:\Python27\lib\socket.py", line 303, in flush
self._sock.sendall(view[write_offset:write_offset+buffer_size])
error: [Errno 10053] An established connection was aborted by the software in
your host machine
----------------------------------------
I've provided a toy server below, you can reproduce the issue by submitting a
request to it with curl and then immediately killing curl:
curl -d "test" http://127.0.0.1:8000/
Toy server code:
===========================
import BaseHTTPServer
import SocketServer
import time
class ThreadedHTTPServer(BaseHTTPServer.HTTPServer):
pass
class RequestHandler(BaseHTTPServer.BaseHTTPRequestHandler):
def do_POST(self):
try:
length = int(self.headers["Content-Length"])
request = self.rfile.read(length)
print "Sleeping. Kill the 'curl' command now."
time.sleep(10)
print "Woke up. You should see a stack trace from the problematic
exception below."
print "Received POST: " + request
self.send_response(200) # <------- This somehow adds to the connection's
buffer!
self.end_headers()
except Exception as e:
print "Exception: " + str(e) # <----- This exception is expected
httpd = ThreadedHTTPServer(("127.0.0.1", 8000), RequestHandler)
httpd.serve_forever()
httpd.server_close()
----------
components: Library (Lib)
messages: 158240
nosy: vdjeric
priority: normal
severity: normal
status: open
title: SocketServer doesn't handle client disconnects properly
versions: Python 2.7
_______________________________________
Python tracker <rep...@bugs.python.org>
<http://bugs.python.org/issue14574>
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