Add Python 3 support for FacebookAuthorization.parse_signed_data

[stianpr]

json.loads was expecting a string, but in python 3 base64decode() return bytes and that is why it was bugged. We fix this by making sure the decoded payload data is in string and that hmac.new() is provided with arguments in bytes. open_facebook.utils.smart_str will do that job correctly in python 2 and 3.

We also use hmac.compare_digest() which is the preferred way to compare those kinds of data to prevent timing analysis. Read more about this on python docs. Though this is only available from python 2.7.7.

Fixes #491.

[stianpr]

I successfully run most of the tests in python 2.7.8, though I'm not sure I should branch out of master because master has 2 breaking tests there?

I manually tested the change in python 3 and it seems to work fine. It would be nice to have more people on Django 1.7 with python 3 verify that it works.

[troygrosfield]

@stianpr, I've been using the app on py3.4.x, django 1.7.x without issues. Your change above looks correct, but the bigger issue here is trying to get travis running successfully again. The django 1.7 issues have to do with south and migrations. I'll open up additional bugs relating to those and we'll track there.

It's hard to accept these changes when the tests are still failing. Let's get those working first then get this change merged in once the tests are passing.

[stianpr]

I'm missing one test that we should have and that's where the cookie parsing fails. It should not throw an exception on those circumstances. I will add that ASAP.

[neokeats]

hi,
they are still issues with python3.
for example : open_facebook\api.py Line 209 refers to the method that no longer exists in py3 : unicode.

so the file is missing at the top

try:
    unicode = unicode
except NameError:
    unicode = str

the same goes for django_facebook\connect.py and django_facebook\utils.py

try :
    from functools import reduce
except:
    pass

is needed in django_facebook\model_managers.py

i had to modify the hash_key method in django_facebook\utils.py :

def hash_key(key):
    import hashlib
    if six.PY3:
        key = key.encode('utf-8')
    hashed = hashlib.md5(key).hexdigest()
    return hashed

[stianpr]

I don't see why you get any exceptions on these lines of code. They don't look pretty but should be valid in python3?

[neokeats]

the unicode method is no longer present in python3 so by doing unicode=unicode we get exception in python 3 and set the method to be the str one in python3

the method reduce was removed too because :

Removed reduce(). Use functools.reduce() if you really need it; however, 99 percent of the time an explicit for loop is more readable.

https://docs.python.org/3.0/whatsnew/3.0.html

[stianpr]

Yeah I know that they are not present in python 3. And they will trigger an exception but they are guarded from doing that in your examples. Don't the except clause work?

Anyway you should create a separat issue for this.

[neokeats]

Oh i see,
they are not the lines with problem.
In the patch and the trunk, they are actually missing so it can't work.
I just provided the modifications needed in order to get it to actually work with python3.