'None' in HTTP headers

[nesdis]

Long story short

Sometimes in file cookies.py the rawdata is of type None and above exception is hit.

def load(self, rawdata):
    """Load cookies from a string (presumably HTTP_COOKIE) or
    from a dictionary.  Loading cookies from a dictionary 'd'
    is equivalent to calling:
        map(Cookie.__setitem__, d.keys(), d.values())
    """
    if isinstance(rawdata, str):
        self.__parse_string(rawdata)
    else:
        # self.update() wouldn't call our custom __setitem__
        for key, value in rawdata.items():
            self[key] = value
    return

Expected behaviour

Why is raw_data given to load of type None?

This is called in function start of C:\Python36\Lib\site-packages\aiohttp\client_reqrep.py

for hdr in self.headers.getall(hdrs.SET_COOKIE, ()):
        try:
            self.cookies.load(hdr)
        except CookieError as exc:
            client_logger.warning(
                'Can not load response cookies: %s', exc)
    return self

Actual behaviour

Looks like self.headers.getall(hdrs.SET_COOKIE, ()) is returning hdr of type None, This looks buggy. It should return actual header or raise stopiteration. At times it returns None.

Steps to reproduce

I have not been able to reproduce this issue. Unfortunately I lost the stack trace console output too. But have debugged till the above point.

Your environment

[asvetlov]

No idea how did you get it.
Looks like some code explicitly pushed None into headers but aiohttp doesn't do it.

Reproducible example would help very much.

[asvetlov]

Multidict doesn't return None if key doesn't exist but some code might push None explicitly.
I pretty sure aiohttp doesn't to it itself.

Closing the issue.
Feel free to open new one if you'll get more info.

[gilbsgilbs]

@asvetlov I'm also affected by this issue, and I'm 100% sure I don't explicitly alter response headers in my code (I don't think I even could because this happens in the post function directly). I'm unable to reproduce locally, but it did happen in production a couple of times (and only one of the remote hosts have produced the issue).

Traceback (most recent call last):
  File ………
    timeout=timeout,
  File "python3.5/site-packages/aiohttp/client.py", line 636, in __aenter__
    self._resp = yield from self._coro
  File "python3.5/site-packages/aiohttp/client.py", line 240, in _request
    yield from resp.start(conn, read_until_eof)
  File "python3.5/site-packages/aiohttp/client_reqrep.py", line 585, in start
    self.cookies.load(hdr)
  File "python3.5/http/cookies.py", line 559, in load
    for key, value in rawdata.items():
AttributeError: 'NoneType' object has no attribute 'items'

Using aiohttp 2.1.0 and python 3.5. The remote server seems to include some headers in its response, including three Set-Cookie. Unfortunately, I can't get the headers value.

Since I got the exception in Sentry, I can provide some more information.

http/cookies.py in load at line 559

rawdata None
self {'SomeString-md5hash': {'comment': '', 'domain': 'www.example.co', 'expires': 'Sun, 24-Sep-2017 13:59:17 GMT', 'httponly': True, 'max-age': '', 'path': '/', 'secure': '', 'version': ''}}

aiohttp/client_reqrep.py in start at line 585

connection Connection<('www.example.co', 80, False)>
hdr None
payload <FlowControlStreamReader 30 bytes eof>
read_until_eof True

aiohttp/client.py in _request at line 240

allow_redirects False
auth None
chunked None
compress None
conn Connection<('www.example.co'', 80, False)>
cookies {'PHPSESSID': {'comment': '', 'domain': '', 'expires': '', 'httponly': '', 'max-age': '', 'path': '', 'secure': '', 'version': ''}, 'SomeString-md5hash': {'comment': '', 'domain': '', 'expires': '', 'httponly': '', 'max-age': '', 'path': '', 'secure': '', 'version': ''}, 'SomeString-anothermd5hash': {'comment': '', 'domain': '', 'expires': '', 'httponly': '', 'max-age': '', 'path': '', 'secure': '', 'version': ''}}
data [censored]
encoding None
expect100 False
handle None
headers <CIMultiDict('User-Agent': 'MyUser-Agent', 'Content-Type': 'application/json')>
history []
json None
max_redirects 10
method 'POST'
params None
proxy None
proxy_auth None
read_until_eof True
redirects 0
req <aiohttp.client_reqrep.ClientRequest object at 0x7fbb1d7a57b8>
self <aiohttp.client.ClientSession object at 0x7fbb2072c208>
skip_auto_headers None
skip_headers []
timeout 300
timer <aiohttp.helpers.TimerContext object at 0x7fbb1d7a56d8>
tm <aiohttp.helpers.TimeoutHandle object at 0x7fbb1f037198>
url URL('http://www.example.co/some/path')
version [1, 1]

Do not hesitate if you need further information. Hope this helps. Thanks.

[asvetlov]

I'm able to reproduce the issue. Fetch from https://reload.dk fails: it splits a header into two, one of them has None as a value.
Pure Python parser works ok but C accelerator fails.
Working on making reliable test.

[fafhrd91]

There are some new commits for http-parse, we should try latest c code

[asvetlov]

It's not release yet.
At first I'd like to check conformance to the following table:

(on_header_field and on_header_value shortened to on_h_*)
 ------------------------ ------------ --------------------------------------------
| State (prev. callback) | Callback   | Description/action                         |
 ------------------------ ------------ --------------------------------------------
| nothing (first call)   | on_h_field | Allocate new buffer and copy callback data |
|                        |            | into it                                    |
 ------------------------ ------------ --------------------------------------------
| value                  | on_h_field | New header started.                        |
|                        |            | Copy current name,value buffers to headers |
|                        |            | list and allocate new buffer for new name  |
 ------------------------ ------------ --------------------------------------------
| field                  | on_h_field | Previous name continues. Reallocate name   |
|                        |            | buffer and append callback data to it      |
 ------------------------ ------------ --------------------------------------------
| field                  | on_h_value | Value for current header started. Allocate |
|                        |            | new buffer and copy callback data to it    |
 ------------------------ ------------ --------------------------------------------
| value                  | on_h_value | Value continues. Reallocate value buffer   |
|                        |            | and append callback data to it             |
 ------------------------ ------------ --------------------------------------------

Maybe you've missed correct processing of Previous name continues state?

[fafhrd91]

interesting. yes, multiple field callbacks are not supported
https://github.com/aio-libs/aiohttp/blob/master/aiohttp/_http_parser.pyx#L139

[asvetlov]

@fafhrd91 have you a time for working on PR or should I take the duty?

[fafhrd91]

I'll fix it.

[asvetlov]

Cool! Thanks!

[fafhrd91]

@nesdis @gilbsgilbs could you confirm if problem fixed in master?

[gilbsgilbs]

Thank you very much @fafhrd91 and @asvetlov for looking into this.

Since I was not able to reproduce the issue locally, I cannot guarantee it fixes my use-case. Anyways, as soon as this is released, I'll deploy to production and after a while get some confidence on whether this is fixed or not. The issue reproduces a few times per week.

[asvetlov]

Let's assume the problem is fixed by #2281
Feel free to create a new issue if needed.

[lock]

This thread has been automatically locked since there has not been any recent activity after it was closed. Please open a [new issue] for related bugs.
If you feel like there's important points made in this discussion, please include those exceprts into that [new issue].
[new issue]: https://github.com/aio-libs/aiohttp/issues/new