Re: [lwip-devel] Missing initialization somewhere?

[Sergey Kubushyn]

On Thu, 13 Oct 2011, Sergey Kubushyn wrote:

A quick addition -- this is definitely DHCP/AUTOIP related. Works like a
charm with static IP, no problems.

The netif list seems to be OK, pointer is the same original netif structure
pointer so it is NOT the list that gets corrupted. It is that particular
flag that gets reset and never set back.

Digging dhcp.c...

> On Thu, 13 Oct 2011, address@hidden wrote:
>
> > Sergey Kubushyn wrote:
> > > The netif is UP and running. If the first packet after reset is ICMP it
> > > keeps running forever. If the first packet after reset is TCP SYN it
> > > _sometimes_ (something like every second reset) makes that netif->flags to
> > > drop its UP flag. If an ICMP packet is in/out (echo req/rply) is processed
> > > before the first TCP SYN everything work fine every time, no failures.
>
> > Hmm, that sounds like some pointer running wild and writing to the memory 
> > region where netif->flags is?
>
> Probably. I'm at it right now.
>
> > > > At which point does the netif go down here?
> > > I don't know yet. ARP goes out OK and received fine. Then when it is time 
> > > to
> > > _SEND_ SYN/ACK netif seems to be down.
> > >
> > > Reception _STILL WORKS_ , it properly receives the retransmitted SYN,
> > > generates a proper SYN/ACK and tries to send it back but it fails again in
> > > ip_route() because netif is presumably down.
>
> > That's strange, reception should only succeed if the netif is up (unless 
> > it's UDP DHCP traffic). For that, netif_is_up() is called in ip_input().
>
> Yep. But it DOES work because it attempts to send a SYN/ACK on each of
> SYN retransmits from the remote.
>
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