Re: [lwip-users] DHCP usage with latest git code version

[Bram Peeters]

Hi Sylvain, 

Sorry for the delay in responding, I took a slight detour running into ;p
 http://lists.gnu.org/archive/html/lwip-devel/2012-01/msg00018.html

Anyway, before diving into the dhcp problem again I synced my lwip to the 
latest sources (I was using something which was several weeks old at this 
point) but now it just works even if I disable LWIP_DHCP_CHECK_LINK_UP again. 

I am not sure which exact change did it (there were like 99 files which had 
changed), but it seems to be working now. 
( Before the it would be (and stay) in DHCP_STATE_OFF when I entered 
dhcp_network_changed, now it is in state DHCP_STATE_SELECTING. )


BTW 1 small bug in the current sources (don't really know where to report this 
so i will piggy back it here):
In tcp_out.c, function tcp_output_segment
There is (around lines 1261) :

#endif /* CHECKSUM_GEN_TCP */
}


should be 

}
#endif /* CHECKSUM_GEN_TCP */

Thank you for your help, 

Bram


-----Original Message-----
From: address@hidden [mailto:address@hidden On Behalf Of Sylvain Rochet
Sent: vrijdag 11 september 2015 11:56
To: Mailing list for lwIP users
Subject: Re: [lwip-users] DHCP usage with latest git code version

Hi Bram,

On Fri, Sep 11, 2015 at 11:48:33AM +0200, Sylvain Rochet wrote:
> Hi Bram,
> 
> On Fri, Sep 11, 2015 at 09:10:28AM +0000, Bram Peeters wrote:
> > Thanks for the clarification!
> > 
> > I had to add 
> > #define LWIP_DHCP_CHECK_LINK_UP     1
> > as well to make
> > 
> > > netif_set_up(&gnetif);
> > > dhcp_start(&gnetif);
> > > Then DHCP will start if netif is already "link up" or at the next "link  
> > > up" event.
> > 
> > work with the netif initially in link down Otherwise the DCHP state 
> > was in DHCP_STATE_OFF mode, and stayed in that mode when 
> > dhcp_network_changed(struct netif *netif) was called when link up 
> > occurred.
> 
> I don't agree. Only dhcp_release()/dhcp_stop() (and obviously initial
> state) switches DHCP to DHCP_STATE_OFF. (Or did you find a bug ?, if 
> so, please investigate a bit more about this issue ;-) )
> 
> The only difference LWIP_DHCP_CHECK_LINK_UP makes is that DHCP is not 
> trying to send discover frames if link is down and then wait for a 
> link up event, otherwise we are sending discover frames whatever the 
> current link state is. The dhcp_network_changed() call just speed it 
> up by cancelling retry timeout.
> 
> 
> Indeed, DHCP without LWIP_DHCP_CHECK_LINK_UP does not care about 
> current link state, I should have mentioned that. So it should work 
> whatever the current shape of your link up/down events handler is.

After thinking about it again. It looks like your lwIP timers(timeouts) are not 
working, which could be an issue with your port.

Sylvain