picotcp tftp support [was Adding IPv4 multicast support]

[Antony Pavlov]

On Mon, 29 Sep 2014 11:45:08 +0200
Daniele Lacamera <daniele.lacamera at tass.be> wrote:

> On Sun, Sep 28, 2014 at 4:22 PM, Antony Pavlov <antonynpavlov at gmail.com> wrote:
> >
> > 1. Do we really need this '#ifdef PICO_SUPPORT_UDP' BEFORE (!)
> > guard macro in pico_dhcp_client.h?
> >
> 
> I moved these in latest PicoTCP commit. Thanks.
> 
> 
> > 2. New pico_tftp_start_{r,t}x programming interface can be used for
> > realization legacy standalone 'tftp' command.
> > But I have no idea how to use this interface for filesystem-over-tftp
> > (it's the modern barebox' tftp realization)!
> >
> > Barebox filesystem interface needs something like this programming
> > interface:
> >
> >   struct pico_tftp_session *s;
> >
> >   s = pico_tftp_new_session_rx(addr, port, family, filename);
> >   ...
> >   filesize = pico_tftp_get_file_size(s);
> >   ...
> >   pico_tftp_receive(s, buf, len);
> >   ...
> >   pico_tftp_receive(s, buf, len);
> >   ... ... ...
> >   pico_tftp_receive(s, buf, len);
> >   ...
> >   pico_tftp_close(s);
> >
> >
> > I mean that receiving process has to be controlled by barebox,
> > not by picotcp. Because a new portion of data is received
> > by filesystem user initiative, not by network stack initiative.
> 
> Thanks for the comments. A few from my side:
> 
> - pico_tftp_receive is non-blocking, and will return immediately if no
> data is available. You always have to be bound to some RX event to be
> sure that your next receive() call is successful, so in some way you
> still want it network-bound.
> 
> - We can implement the get_file_size, but not all servers will support
> it. Michele has a strategy for developing more advanced TFTP features,
> he will post on it later

  I want just to say that barebox tries to get file size if it's possible.
  Please see tftp_parse_oack() function in fs/tftp.c:

   if (!strcmp(opt, "tsize"))
       priv->filesize = simple_strtoul(val, NULL, 10);

  This priv->filesize is used in tftp filesystem stat() call realization.
  So it's reasonable to give barebox a means to set priv->filesize
  after switching to picotcp.

-- 
Best regards,
  Antony Pavlov