[Bug 1915819] [NEW] 'NoneType' object has no attribute 'encode' in requestReceived() when multipart body doesn't include content-disposition
Launchpad Bug Tracker
1915819 at bugs.launchpad.net
Thu Feb 18 16:29:59 UTC 2021
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[impact]
python-twisted errors out with "'NoneType' object has no attribute
'encode' in requestReceived()" when it tries to parse a multipart mime
message and python3.7+ is used. This happens because before commit
cc3fa20 in cpython, cgi.parse_multipart ignored parts without a name
defined in "content-disposition" (or parts without headers for that
matter) but after 3.7+ the return of the function can now contain
NoneType keys, which fail to encode.
[scope]
Even though this bug affects all python3-twisted releases, I'll backport
the fix just to Focal, Groovy and Hirsute. Bionic and Xenial do not have
Python 3.7 as the default interpreter (required to trigger the issue),
and the delta in python3-twisted might be to big to backport as the
current packages do not contemplate _PY37PLUS at all.
Fixed upstream with commit 310496249, available since 21.2.0rc1
[test case]
1. Save the following code as webserver.py
from twisted.application.internet import TCPServer
from twisted.application.service import Application
from twisted.web.resource import Resource
from twisted.web.server import Site
class Foo(Resource):
def render_POST(self, request):
newdata = request.content.getvalue()
print(newdata)
return ''
root = Resource()
root.putChild("foo", Foo())
application = Application("cgi.parse_multipart test")
TCPServer(8080, Site(root)).setServiceParent(application)
2. Save the following code as client.py (python3-httplib2 is required)
#!/usr/bin/env python
import httplib2
def http_request(url, method, body=None, headers=None, insecure=False):
"""Issue an http request."""
http = httplib2.Http(disable_ssl_certificate_validation=insecure)
if isinstance(url, bytes):
url = url.decode("ascii")
return http.request(url, method, body=body, headers=headers)
url = "http://localhost:8080"
method = "POST"
headers = {'Content-Type': 'multipart/form-data; boundary="8825899812428059282"'}
emptyh = '--8825899812428059282\n\n--8825899812428059282--'
print("== BODY: " + emptyh + "\n")
response, content = http_request(url, method, emptyh, headers)
3. Run the server with "twistd3 -y webserver.py"
4. Run the client
5. twistd will fail to encode the key and will drop this traceback in the log file (twistd.log)
2021-02-16T13:41:39+0100 [_GenericHTTPChannelProtocol,7,127.0.0.1] Unhandled Error
Traceback (most recent call last):
File "/usr/lib/python3/dist-packages/twisted/python/log.py", line 103, in callWithLogger
return callWithContext({"system": lp}, func, *args, **kw)
File "/usr/lib/python3/dist-packages/twisted/python/log.py", line 86, in callWithContext
return context.call({ILogContext: newCtx}, func, *args, **kw)
File "/usr/lib/python3/dist-packages/twisted/python/context.py", line 122, in callWithContext
return self.currentContext().callWithContext(ctx, func, *args, **kw)
File "/usr/lib/python3/dist-packages/twisted/python/context.py", line 85, in callWithContext
return func(*args,**kw)
--- <exception caught here> ---
File "/usr/lib/python3/dist-packages/twisted/internet/posixbase.py", line 614, in _doReadOrWrite
why = selectable.doRead()
File "/usr/lib/python3/dist-packages/twisted/internet/tcp.py", line 243, in doRead
return self._dataReceived(data)
File "/usr/lib/python3/dist-packages/twisted/internet/tcp.py", line 249, in _dataReceived
rval = self.protocol.dataReceived(data)
File "/usr/lib/python3/dist-packages/twisted/web/http.py", line 2952, in dataReceived
return self._channel.dataReceived(data)
File "/usr/lib/python3/dist-packages/twisted/web/http.py", line 2245, in dataReceived
return basic.LineReceiver.dataReceived(self, data)
File "/usr/lib/python3/dist-packages/twisted/protocols/basic.py", line 579, in dataReceived
why = self.rawDataReceived(data)
File "/usr/lib/python3/dist-packages/twisted/web/http.py", line 2252, in rawDataReceived
self._transferDecoder.dataReceived(data)
File "/usr/lib/python3/dist-packages/twisted/web/http.py", line 1699, in dataReceived
finishCallback(data[contentLength:])
File "/usr/lib/python3/dist-packages/twisted/web/http.py", line 2115, in _finishRequestBody
self.allContentReceived()
File "/usr/lib/python3/dist-packages/twisted/web/http.py", line 2224, in allContentReceived
req.requestReceived(command, path, version)
File "/usr/lib/python3/dist-packages/twisted/web/http.py", line 898, in requestReceived
self.args.update({
File "/usr/lib/python3/dist-packages/twisted/web/http.py", line 899, in <dictcomp>
x.encode('iso-8859-1'): \
builtins.AttributeError: 'NoneType' object has no attribute 'encode'
[regression potential]
This affects the returned dictionaries with non-str keys, which were
discarded in python3.6 or earlier before they reached twisted, so
patching this will make its behavior consistent.
** Affects: twisted (Ubuntu)
Importance: Undecided
Status: New
** Affects: twisted (Ubuntu Focal)
Importance: Undecided
Status: New
** Affects: twisted (Ubuntu Groovy)
Importance: Undecided
Status: New
** Affects: twisted (Ubuntu Hirsute)
Importance: Undecided
Status: New
** Tags: patch sts
--
'NoneType' object has no attribute 'encode' in requestReceived() when multipart body doesn't include content-disposition
https://bugs.launchpad.net/bugs/1915819
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