* Matthew Toseland <toad at amphibian.dyndns.org> [2007-09-25 20:22:24]:

> On Tuesday 25 September 2007 17:07, bbackde at googlemail.com wrote:
> > My point is not to change the principles of the TestDDA
> > implementation. The proposal describes a different way of
> > implementation that fits for stateless clients. The current
> > implementation requires that you send out-of-order testdda requests if
> > the node sends an error, and then the client have to resend the
> > original request. The proposal ties the testdda to the initiating
> > request, and the node remembers the request until the testdda is
> > finished.
> 
> The basic principle here seems sound. Making clients' life a bit easier is 
> generally a good thing. Nextgens?

Send a patch or fill in a ticket on the BTS. We discussed it 6 months ago
(http://archives.freenetproject.org/message/20070414.083225.647d5e15.en.html)
suggestions would have been welcome then but aren't anymore . I ended up
implementing what we agreed on and have no plan to spend any time
on that in the near future. By the way if you really want to make a
basic, simple client I suggest you compute the FileHash and send it
everytime. 

NextGen$

> > 
> > On 9/25/07, Florent Daigni?re <nextgens at freenetproject.org> wrote:
> > > * bbackde at googlemail.com <bbackde at googlemail.com> [2007-09-25 
> > > 17:29:47]:
> > >
> > > > > Also, if the filesystem is readonly, you *will* need to use FileHash 
> instead
> > > > > of TestDDA.
> > > >
> > > > This comment let me start thinking about the TestDDA design. Because
> > > > if the directory is read-only, the client have to handle the node
> > > > error (node cannot write the file) and the client must restart the
> > > > request. This is complicated and maybe confusing. The following
> > > > proposal tries to deal with this. I hope it is well thought.
> > > >
> > >
> > > Well, I think that the current one is well thought... See below
> > > limitations of your approach :
> > >
> > > > ------------------------------------------------
> > > >
> > > > Proposal for a alternative implementation for TestDDA
> > > >
> > > > Reason for a new proposal:
> > > > The current TestDDA implementation requires the client to implement
> > > > more things than really
> > > > needed. This proposal makes it easier for clients because its a simple
> > > > question-and-answer
> > > > game with the node. The node sends the right 'questions' to the
> > > > client, because he knows what
> > > > to ask. This allows easy-to-implement stateless clients.
> > > >
> > > > If needed, I could explain the advantages for clients in more detail.
> > > > But I think if you compare the existing implementation of TestDDA with
> > > > this proposal you
> > > > encounter that this proposal is a more consistent implementation. Btw
> > > > this handles multiple concurrent
> > > > TestDDA requests (each request is tied to a ClientGET or ClientPUT).
> > > >
> > > > One does not fits all, so I think both implementations are useful for
> > > > the one or the other client.
> > > > This proposal is for clients that want to send a request, and handle
> > > > all following messages
> > > > in a different part of the code. They do not remember the original
> > > > send request, so its hard
> > > > for them to resend the request on failure.
> > > >
> > > > The following proposal is fully node driven, making the handling
> > > > easier for clients (e.g. the
> > > > decision if a filehash must be send is done by the node, because only
> > > > he knows if he can write the
> > > > required file to the target directory or if this is already denied
> > > > (read-only directory).
> > > >
> > > > Note: this new impl must be enabled using a new parameter on
> > > > ClientPUT/ClientGET. The is no need
> > > >      to change existing clients.
> > > >
> > > > For each follow-on message the identifier that the client sent with
> > > > the first request is used,
> > > > because this messages belong to the same client request.
> > > >
> > > > ClientPUT:
> > > > -----------
> > > > - client sends ClientPUT to node, with new parameter indicating to use
> > > > the new testdda impl
> > > >  (node now needs to know if client is allowed to READ from the
> > > > directory where the file resides)
> > > > - node checks if the current socket is already authenticated to READ
> > > > from the directory
> > >
> > > It's not because you're allowed to read /etc/passwd and you sent the
> > > node its filehash that you should be allowed to read everything in
> > > /etc... (Maybe I'm missunderstanding what you're proposing)
> > >
> > > > - if YES, do the ClientPUT
> > > > - if NO (proceed as in current TestDDA implementation):
> > > > - node tries to create a new file with random content in the directory
> > > > - if OK, send message to client asking to read this new file and
> > > > return the content for verification
> > > > - if NOT OK, send message to client asking for a filehash of this file
> > >
> > > Nothing prevents clients from sending FileHash every time...
> > >
> > > >  (OR maybe for a hash of a part of the file! much lesser resource
> > > > consumption. consider big files on
> > > >   network shares or on DVDs! But this may by more insecure.)
> > >
> > > We have already discussed asking for hashes of parts of files; We can't
> > > do that. I can predict most of your /etc/shadow ; shall I be allowed to
> > > upload it ? If I dunno about the part you're asking can't I ask again
> > > 'til you ask me for a part I know ?
> > >
> > > NextGen$



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