Re: [lwip-users] Re: Using lwip for writing a minimal HTTP proxy

[Mandeep Sandhu]

On Fri, Sep 25, 2009 at 3:46 PM, Kieran Mansley <address@hidden> wrote:
> On Fri, 2009-09-25 at 15:15 +0530, Mandeep Sandhu wrote:
>> On Fri, Sep 25, 2009 at 1:44 PM, Kieran Mansley <address@hidden> wrote:
>> > Can you show us how you create the two netifs?
>>
>> The ECOS ethernet driver sets up the interface as follows:
>>
>> netif_add()
>> if (<configured as default>)
>>         netif_set_default()
>> netif_set_up()
>
> It was the argument values you're giving to those functions that I was
> particularly interested in, but I think you've already got to the bottom
> of the problem so not really necessary anymore.
>
>> One way to workaround this is to change the default interface to the
>> second i/f (the one which connects me to the other server) when it
>> comes up i.e gets an addr from DHCP.
>>
>> Do you think it's a good idea to change the def interface at runtime?
>
> Should be fine, but I think you should be able to set eth1 as the
> default from the beginning.
>
>> I need the first interface(eth0) to be the default one, otherwise the
>> DHCP server running on it won't work.
>
> I'd be interested in why DHCP server doesn't work on a non-default
> interface.  Can you explain why?  If it did you could just have eth1 as
> the default interface to start with.

Well, if both eth0 and eth1 are up, and eth1 is marked as default then
it'll send the DHCP response packets out of that interface. The DHCP
resp will be UDP packets with dest addr as broadcast.

I had asked Q's related to this a few days back. Even while receiving
the bcast packets they were getting dropped because of the src IP
check in ip_input. So I have to comment out that piece of code to make
it work. I've filed a bug on savanah regarding this issue:
https://savannah.nongnu.org/bugs/?27390

Regards,
-mandeep


>
> Kieran
>
>
>
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