I was trying to put
session['logged_in'] = True
in the session, but in another blueprint it doesn't persist... Why is that?
Is there any better way to keep something in the session?
Extended:
I have a blueprint giving a form to login. When done and submitted, it will set a session key like above. Then it redirects via
return redirect(url_for('admin.index'))
to admin page where If I call the key via
session.get('logged_in')
I get "None" Instead of the True or False one.
I think I understand your confusion now~
Your flask session won't store anything on the server.
the 'session' dict is filled by the cookies from the client request.
Again. that is:
client make login request to server, and got a [login success] response as well as a [cookies] which contains the !!!sessionINFO!!! you think are stored on the server side.
Next time, you must send the whole cookies to the server again, then your session in the server may have data.
Browser will do this for you.
If you use a local client, say python requests library. Then be sure you are making requests with session (for requests-lib, it's requests.Session())
------------------OLD-------------------------------------
Though not an expert, but the case you described should not have happened.
The session is cookies data encrypted with a secret, if you have gone through the document mentioned by Beqa.
Just set
app.secret = '........'
And use session as a dict.
just FYI,
client request---->server (encrypt your_data 'logged_in' and client_relating_data 'maybe: ip, host or etc.', and put the encrypted info in cookies 'session=....') ------> client (get response with cookies)
client request again -----> server (decrypt the cookie 'session=...' with your secret), find the 'logged_in' data and know you are logged in.)
the cookies is something like below.
So, I'm not sure what's actually your trouble when using session, and put some basic information here. Just hope it helps in case.
Related
I am working on a project in which i am working on a signup/login module. I have implemented the sessions in webapp2 python successfully. Now i want to implement the remember me feature on login. I am unable to find anything which can help me. I do know that i have to set the age of session. But i do not know how. Here is my session code.
def dispatch(self):
# Get a session store for this request.
self.session_store = sessions.get_store(request=self.request)
try:
# Dispatch the request.
webapp2.RequestHandler.dispatch(self)
finally:
# Save all sessions.
self.session_store.save_sessions(self.response)
#webapp2.cached_property
def session(self):
# Returns a session using the default cookie key.
return self.session_store.get_session()
Config:
config = {}
config['webapp2_extras.sessions'] = {
'secret_key': 'my-super-secret-key',
}
Kindly help me.
First in case you don't know the difference between sessions and cookies
What is a Cookie? A cookie is a small piece of text stored on a
user's computer by their browser. Common uses for cookies are
authentication, storing of site preferences, shopping cart items, and
server session identification.
Each time the users' web browser interacts with a web server it will
pass the cookie information to the web server. Only the cookies stored
by the browser that relate to the domain in the requested URL will be
sent to the server. This means that cookies that relate to
www.example.com will not be sent to www.exampledomain.com.
In essence, a cookie is a great way of linking one page to the next
for a user's interaction with a web site or web application.
.
What is a Session? A session can be defined as a server-side storage of
information that is desired to persist throughout the user's
interaction with the web site or web application.
Instead of storing large and constantly changing information via
cookies in the user's browser, only a unique identifier is stored on
the client side (called a "session id"). This session id is passed to
the web server every time the browser makes an HTTP request (ie a page
link or AJAX request). The web application pairs this session id with
it's internal database and retrieves the stored variables for use by
the requested page.
If you want to implement something like "remember me" you should use cookies because data stored in session isn't persistent.
For setting and getting cookies in webapp2:
response.headers.add_header('Set-Cookie', 'remember_me=%s' % some_hash)
request.cookies.get('remember_me', '')
I strongly recommend you to read this article that has explained this stuff thoroughly.
I am having a weird problem with Django. I set certain cookies on the client, but those cookies do not appear in the Django request.
The cookies properly appear in the client as follows:
"class_year_only=yes; email_status=yes; exit_status=yes; class_year_only_status=yes; nmstat=1448946715685; __utma=96992031.1943662208.1449612961.1449621554.1449704668.3; __utmz=96992031.1449612961.1.1.utmcsr=(direct)|utmccn=(direct)|utmcmd=(none); csrftoken=Oe2A6Qn7pwUshDEFAhyNa4dtGRajVe4S"
However, the Django request only shows the following cookies:
"{'csrftoken': Oe2A6Qn7pwUshDEFAhyNa4dtGRajVe4S, '__utma':96992031.1943662208.1449612961.1449621554.1449704668.3, '__utmz':96992031.1449612961.1.1.utmcsr=(direct)|utmccn=(direct)|utmcmd=(none), 'nmstat':1448946715685}"
Why aren't the other cookies being sent?
I figured out the problem. I needed to set path to /. The path in the client side cookie, used a subdomain which was the cause of the problem. Not sure why, as the subdomain was correct.
In order to see this possible error you need to open two browsers and some plug-in to get/set cookies.
If you create a new project in django 1.7 and access to the admin site (/admin), and login succesfuly in the first broser and get the sessionid and csrftoken cookies and set them into the second browser login page and set a random user and password, you obtain a CSRF error and if you go back in the browser you are logged in.
how can avoid this?
I suppose, you can obtain same result just by copying sessionid cookie to another browser and navigating /admin. You don't need csrftoken to reproduce this issue. It's called sessionid stealing and all frameworks I know are vulnerable to this type of attack.
To avoid it, set SESSION_COOKIE_SECURE = True (default False) to protect your sessionid cookie from man-in-the-middle attacks. You will also need to install ssl certificate on your production server. Then configure it to redirect all http:// requests to https://. S in https stands for secure, this means all traffic between client and server is encrypted, and no one between client and server (client's ISP, server's hosting provider, proxies, etc) can read any data is sent. Including session cookie value.
And use SESSION_COOKIE_HTTPONLY = True (default) to protect session cookie from stealing via XSS. HTTPONLY means that this cookie will be sent with each http request, but won't be accessible from client's browser via javascript. So if some malware javascript managed to run in client browser, it will not have access to session cookie anyways.
Good tutorial on configuring secure django server can be found here: https://security.stackexchange.com/a/8970
I would like to know, when is the right moment and how to check the browser cookies support.
I understand I have to check the next request and for instance, with beaker, looking for the session key _creation_time or request.headers['Cookie']... and raise an exception if not found but I don't want to do that or something similar for every request. Some parts of my application don't require cookies, like the home page or info, faq page...
When a user logs out, the session gets deleted or invalidated and I used to redirect to the home view, if I check the session key at that moment, I'll not find it but it doesn't mean there is this issue.
An example I used at the beginning of login view:
try: request.headers['Cookie']
except KeyError:
return HTTPFound(location=request.route_url('home'))
Please also note that if I try to print an error message using request.session.flash(msg, 'error') or use the snippet again at the beginning of the home view and render a message with the template using a control return variable, after logout it will be erroneous displayed.
I am looking for the most elegant way to resolve issue...maybe subscribe to a event?...write down a function to call in some interested view?
There are a few things that could the cause of your problems.
Before I continue... FYI Pyramid uses WebOb to handle request and response objects
WebOb Overview
WebOb Class Documentation
Scenario 1
If you call set_cookie under Pyramid , and then do a redirect, the set_cookie will not be sent. This is because redirects create a new response object.
There are a few ways around this:
The most straightforward is to just copy response headers into the cookie when you raise/return a redirect
return HTTPfound( "/path/to/redirect", headers=[ (k,v) for (k,v)\
in self.request.response.headers.iteritems() if k == 'Set-Cookie'] )
OR
resp = HTTPFound(location='/path/to/redirect')
return self.request.response.merge_cookies(resp)
I should also note that MOST browsers accept cookies on redirects, however Safari does not.
another way is to use pyramid's hooks to convert cookies behind the scenes. i wrote subscribers that automate this. they're on pypi and github. https://github.com/jvanasco/pyramid_subscribers_cookiexfer
Scenario 2
There are two ways of handling sessions in Pyramid. Pyramid has its own session library, and then there is Beaker, which handled sessions for Pylons and has Pyramid support that many people use. I can't speak of pyramid.session, but Beaker has two modes to kill the session:
delete()
Delete the cookie, and clear the session
invalidate()
Clear the contents and start a new session
If you call invalidate(), the Beaker session cookie stays the same and all the session data is cleared -- so you can start storing new data into an empty session object.
If you call delete(), the cookie gets killed as does the session data. If you put new information into the session, IIRC, it will go into a new sessionid / cookie . However, as I noted in the first part above, set_cookie will get called but then thrown out during the redirect. So if you delete() the session and then don't migrate the set_cookie headers... the client will never receive a session identifier.
Some example behaviors of cookies under pyramid
Behavior of redirect
User visits site and is given cookie: SessionId=1
User clicks login
App saves login status to session "1"
App calls set_cookie with "LoggedIn=1"
App calls redirect to /home
Redirect sent, no cookies
User lands on /home
App only sees cookie for "SessionId=1"
Behavior of delete with redirect:
User clicks logout
App calls 'delete()' on session, killing the datastore and placing a set_cookie in request.response to expire the old cookie. if a new sessionid is created, that is sent as well.
If app renders a response, then client receives cookies
If app redirects, client does not receive headers to expire the cookie or set up a new one
Behavior of invalidate with redirect:
User clicks logout
App calls 'invalidate()' on session, killing the datastore
App sets a custom "loggedout=0" cookie
If app renders a response, then client receives cookies
If app redirects:
Client does not receive "loggedout=0" header
Client still has the old session cookie, but it was invalidated/purged on the backend, so they are effectively locked out.
side note: I personally don't like using the request.headers interface -- which handles all headers -- to get at cookies. I've had better luck with request.cookies -- which returns a dictionary of cookies.
I'm using tornado and the TwitterMixin and I use the following basic code:
class OauthTwitterHandler(BaseHandler, tornado.auth.TwitterMixin):
#tornado.web.asynchronous
def get(self):
if self.get_argument("oauth_token", None):
self.get_authenticated_user(self.async_callback(self._on_auth))
return
self.authorize_redirect()
def _on_auth(self, user):
if not user:
raise tornado.web.HTTPError(500, "Twitter auth failed")
self.write(user)
self.finish()
For me it works very well but sometimes, users of my application get a 500 error which says:
Missing OAuth request token cookie
I don't know if it comes from the browser or the twitter api callback configuration.
I've looked through the tornado code and I don't understand why this error
appears.
Two reasons why this might happen:
Some users may have cookies turned off, in which case this won't work.
The cookie hasn't authenticated. It's possible that the oauth_token argument is set, but the cookie is not. Not sure why this would happen, you'd have to log some logging to understand why.
At any rate, this isn't an "error," but rather a sign the user isn't authenticated. Maybe if you see that you should just redirect them to the authorize URL and let them try again.
I found the solution !!
It was due to my DNS.
I didn't put the redirection for www.mydomain.com and mydomain.com so sometimes the cookie was set in www. and sometimes not then my server didn't check in the good place, didn't find the cookie and then send me a 500 error.
The reason this was happening to me is that the Callback URL configuration was pointing to a different domain.
Take a look at the settings tab for your application at https://dev.twitter.com/apps/ or if the users getting the error are accessing your site from a different domain.
See: http://groups.google.com/group/python-tornado/browse_thread/thread/55aa42eef42fa1ac