Content-type should not be set to ""

[Timur Alperovich]

When performing an upload, the content-type may be set to an empty string (in client.py):

 978 if content_type is not None:
 979 headers['Content-Type'] = content_type
 980 else: # python-requests sets application/x-www-form-urlencoded otherwise
 981 headers['Content-Type'] = ''

This breaks against certain servers (I've found this to be a problem in Jersey), which return 400 error for an invalid content type (""). Can swiftclient default to a valid type, e.g. binary/octet-stream? Happy to submit a small patch to change this.

[Jason Cwik (13-jcsoz-k4)]

Per RFC7231, the format of this field is

     media-type = type "/" subtype *( OWS ";" OWS parameter )
     type = token
     subtype = token

https://tools.ietf.org/html/rfc7231#section-3.1.1.1

Therefore, an empty string is *not* valid. As Timur says, this can cause issue with clients and servers that are proxying the requests.

An appropriate fix here is to default to "application/octet-stream".

[Timur Alperovich (timur-alperovich)]

Suggested a fix: https://review.openstack.org/#/c/472541/

[Alistair Coles (alistair-coles)]

the work around to set content-type='' in the client is not required with requests>=2.4.0:

```

swift@vm-15:~/swift$ python3 -c "import requests; print(requests.post('http://httpbin.org/post', data=b'hi', headers={}).text)"
{
  "args": {},
  "data": "",
  "files": {},
  "form": {
    "hi": ""
  },
  "headers": {
    "Accept": "*/*",
    "Accept-Encoding": "gzip, deflate",
    "Connection": "close",
    "Content-Length": "2",
    "Content-Type": "application/x-www-form-urlencoded",
    "Host": "httpbin.org",
    "User-Agent": "python-requests/2.3.0 CPython/3.5.2 Linux/4.8.0-52-generic"
  },
  "json": null,
  "origin": "79.68.30.192",
  "url": "http://httpbin.org/post"
}

swift@vm-15:~/swift$ pip3 install requests==2.4.0Collecting requests==2.4.0

...

swift@vm-15:~/swift$ python3 -c "import requests; print(requests.post('http://httpbin.org/post', data=b'hi', headers={}).text)"
{
  "args": {},
  "data": "hi",
  "files": {},
  "form": {},
  "headers": {
    "Accept": "*/*",
    "Accept-Encoding": "gzip, deflate",
    "Connection": "close",
    "Content-Length": "2",
    "Host": "httpbin.org",
    "User-Agent": "python-requests/2.4.0 CPython/3.5.2 Linux/4.8.0-52-generic"
  },
  "json": null,
  "origin": "79.68.30.192",
  "url": "http://httpbin.org/post"
}

swift@vm-15:~/swift$ pip3 install requests -U
Collecting requests

...

swift@vm-15:~/swift$ python3 -c "import requests; print(requests.post('http://httpbin.org/post', data=b'hi', headers={}).text)"
{
  "args": {},
  "data": "hi",
  "files": {},
  "form": {},
  "headers": {
    "Accept": "*/*",
    "Accept-Encoding": "gzip, deflate",
    "Connection": "close",
    "Content-Length": "2",
    "Host": "httpbin.org",
    "User-Agent": "python-requests/2.17.3"
  },
  "json": null,
  "origin": "79.68.30.192",
  "url": "http://httpbin.org/post"
}

```

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/472541
Committed: https://git.openstack.org/cgit/openstack/python-swiftclient/commit/?id=32f6b3c642fd5830a63e06ea4fac86956160312f
Submitter: Jenkins
Branch: master

commit 32f6b3c642fd5830a63e06ea4fac86956160312f
Author: Timur Alperovich <email address hidden>
Date: Thu Jun 8 23:47:14 2017 -0700

    Do not set Content-Type to '' with new requests.

    Previously, python-swiftclient worked around a requests issue where
    Content-Type could be set to application/x-www-form-urlencoded when
    using python3. This issue has been resolved and a fix released in
    requests 2.4 (fixed in subsequent releases as well). The patch makes
    the workaround conditional on the requests version, so that with
    sufficiently new requests libraries, the Content-Type is not set.

    For reference, requests 2.4 was released August 29th, 2014. The
    specific issue filed in the requests tracker is:
    https://github.com/requests/requests/issues/2071.

    Related-Change: I035f8b4b9c9ccdc79820b907770a48f86d0343b4
    Closes-Bug: #1433767

    Change-Id: Ieb2243d2ff5326920a27ce8c3c6f0f5c396701ed

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/python-swiftclient 3.4.0 release.