Re: [lwip-users] what the NETIF_FLAG_DHCP is for?

[Jonathan Larmour]

Kiran Bacchewar wrote:
> HI all,
>  
> i want to enable the DHCP in lwip. iam using lwip 1.3 version.
>  
> i made the fallowing initialization...
>  
> #define LWIP_DHCP    1                (in lwipopts.h)
> ip_addr.addr=0;                                (in init.c file)
> netmask.addr=0; 
> gw.addr=0;
> netif_add(netif,ip_addr,netmask,gw,state,drvr_init,ethernet_input);
> netif_set_default(netif);
> netif_set_up(netif1);
> dhcp_start(netif);

I assume that netif_add isn't literally what you have as I would have 
expected something like netif_add(netif, &ip_addr, &netmask, &gw, 
netif->state, ....).

and the netif_set_up(netif1) should not have the "1".

But I guess that's just you simplifying for here.

> by this initialization, i can see the DISCOVER,OFFER,REQUEST,ACK packets 
> sent to/from by the lwip as per the DHCP standard.... but when i ping 
> for the offerd address, the board(on which lwip is ported)  doesn't 
> respond... 
>  
> after doing some debug... i found that there is no ip address assigned 
> in the netif->ip_addr, its assignde to 'zero' the initial value...
>  
> and if i disable the DHCP and give
> 1>the static ip addresses
> 2>make LWIP_DHCP  0  
> 3>remove the dhcp_start()
>  
> the ping, all the other appliacations works fine....
> what might be the problem??? is the DHCP initialization right??? am i 
> missing some thing???

I can't instantly see the issue. Are you using the tcpip thread?

In lwipopts.h you could enable LWIP_DEBUG and set DHCP_DEBUG to 
LWIP_DBG_ON to get debug output from the dhcp module to see what it thinks 
is going on.

Or alternatively you can debug the dhcp_recv() function in dhcp.c from 
your debugger, and see why it isn't calling dhcp_bind().

> what is the significance of NETIF_FLAG_DHCP?? where it should be set 
> into the netif flags in the initialization sequence???

You don't need to set it. It gets set by dhcp_start.

Jifl
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