picotcp tftp support [was Adding IPv4 multicast support]

[Daniele Lacamera]

On Wed, Jul 16, 2014 at 8:30 AM, Sascha Hauer <s.hauer at pengutronix.de> wrote:
> Right now the network users register to a udp port and provide a handler
> which is called whenever a packet to this port is received. The
> prototype for this function is:
>
> struct net_connection *net_udp_new(IPaddr_t dest, uint16_t dport,
>                 rx_handler_f *handler, void *ctx);
>
> Then network users can send packets on this connection:
>
> int net_udp_send(struct net_connection *con, int len);
>
> The function returns after the packet has been sent.
>
> The network user has to keep the ball rolling by calling
>
> void net_poll(void);
>
> in a loop. This function will call into the network drivers receive
> function and dispatch the received packets. ARP packets are handled
> internally, the UDP packets are passed to the registered handlers.
>
> The handlers usually will send answers to received packets (so a tftp
> client will send an ack here or request the next packet).
>
> Usually the loop calling net_poll() also has some functionality to
> detect progress and will send the last packet again if it was lost.
>
> Hope that explains the networking model in barebox.
>

Hi Sascha,

Thanks a lot for this clarification. The mechanism you described is
the same as the native execution model of PicoTCP, and looking around
in the code it seems that looping around net_poll() was in fact the
way to go.

to Antony: I will improve TFTP first, by allowing multiple sessions at
the same time. I will keep you posted on the progress.

Thanks,

/d