Right now the session is a combination of client ip and a uuid. The
uuid prevents session hijacking.

The ip serves two purposes:
- the server can find expired sessions more easily
- the apps the reject sessions coming from wrong ip thus further
protecting against hijacking.

On Mar 15, 11:55 am, Jonathan Lundell <jlund...@pobox.com> wrote:
> On Mar 15, 2011, at 7:15 AM, Corne wrote:
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> > We (again) looked deeper into what is really happening; and it is yet
> > different.
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> > What we ran into is the following:
> > We tried to set a session_id our self based on information in the url,
> > which in this case resulted in calling the session connect code (where
> > it went wrong) twice per request.
>
> > In case a cookie was send; there is no problem at all.
> > Session is handled by web2py like always (except for the fact that
> > it's done twice).
> > In case there is no cookie send; there is a problem.
> > The first call to connect (web2py internal) has no session_id, so a
> > new one is generated.
> > The second call to connect (our plugin) has a session id so it's
> > handled ok.
>
> > In the end of the request, the session changes are written. But in our
> > case (without cookie) the var session_new is True (and the session
> > file is (re)opened with 'wb').
> > Opening with 'wb' does seem to change the file handle. The request
> > that is handled by a differend process at the same time will now have
> > an invallid session.
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> > This also explains the fact that reopening the session file seemed to
> > solve the problem except for the fact that the real problem is
> > somewhere else.
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> > I guess that using connect is something that is / should be allowed
> > (it's in the book), this is also the way to, for example use sessions
> > from an other application.
> > and there the same issue could apply:
> > in case someone uses connect to just use a session from a different
> > application. The first connect from web2py might result in creating a
> > new session. While the connect which is issued later by the user does
> > result in an existing session.
>
> When you set your own session_id, does the corresponding session file always 
> exist? If it does not, session.connect is going to discard that session_id 
> and generate a new uuid. I don't see a way to force session.connect to create 
> a session file with a predetermined id.
>
> If that's not an issue, you could try setting response.session_new = False 
> before calling session.connect; session.connect probably ought to do that 
> itself at the beginning of the not-db logic branch. We could also add a 
> session-id argument to allow the caller to force an id, I suppose, but I'd 
> like to be a little clearer on your use case.
>
> Doesn't creating a session id based on the request url open up a session to 
> hijacking?

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