Re: [Pengfork-devel] Improvements

[Jean-Charles Salzeber]

On Wed, Aug 21, 2002 at 23:20, Nicolas Burrus wrote:
> 
> I have nothing against C :) I think too it is a better langage for this kind 
> of application, I just didn't know you wanted to rewrite all from scratch, 
> but it's a good idea, I think the only really good things to extract for 
> pengaol is the AOL protocol, compression, etc ... but it needs a complete 
> rebuild.

True, actually, I've completly rebuild the modem driver, make some basic
configuration functions. 
Now, I'm trying to make the AOL protocol working...
I've made types, basic functions for sending/receiving packets... it
seems to work.
I can initialize the protocol and log into the server.

I will now try to make the IP functions working. It doesn't seem to be
so hard...

> 
> BTW, the portability problems won't mainly come from the language I think 
> (c++ 
> is quite portable), but from the OS's particularity with low level system 
> calls ...

Yes, the main difficulty is the interface, see below...

> 
> > I think a third-party 'pengctl' program could be used to disconnect.
> > This program could also start peng, have some statistics information, and
> > could be used to control peng with the GUI and eventually others
> > third-party programs like an email/newgroups/... wrapper.
> 
> Ok, why not, it would be nice.
> 
> An idea just come to me, would it be possible to make a kernel module 
> implementing the AOL ppp protocol, and then use pengaol as an higher level 
> program interfacing modem, cable, etc ... with this driver ? I'm not familiar 
> at all with kernel ppp stuff, so my idea is certainly impracticable, but I 
> think it merits some investigation, isn't it ? And in this case, is it 
> impossible to use pppd, maybe with a little patch ?
> 

I've thinked about some possibility for the IP interface:
  * As in previous version, use tun interface:
       + Very easy to implement
       + This choice is logic, AOL use a tunneling protocol
       - Only portable on Linux/*BSD/Solaris(2.6,7.0,8.0)
       ...

  * use BPF on any interface:
       + We could use any existing interface
       + Would work on several systems
       - It is a bit tricky
       ...

  * Completly re-encapsulating IP under ppp and launch pppd:
       + we could use existing code & program (pppd)
       + Would be extremly portable
       - Need much work to implement (I think...?)
       - would be more CPU intensive
       ...
       
  * Making a kernel module:
       + would be clean (AOL make this for windows)
       - definitively *not* portable
       ...

To be continued... (some other ideas?)

So, for now I'm planning to use the tun interface, it will make my life
easier ;)
But for the long time, BPF and the re-encapsulation on top of PPP would
be good choices (but I don't know if the last one is possible).

I've also heard that the last AOL protocol (version 7.0) is a modified
PPP, so here we could make a patch to pppd and use it. It would be nice!
For the version 3.0 (in peng), I don't think a patch is possible, this
protocol has really nothing to do with PPP.
       
> PS: I have some trouble with my mail server, hope you won't receive the mail 
> twice.
Not a problem for my procmail & formail rules :)

> -- 
> Nicolas Burrus

JC

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