[lwip-users] Re: [lwip] changes in IP/UDP for DHCP

[leon . woestenberg]

Hello Adam,

> > 1.2) Changes to udp.c for DHCP
> >
> > --begin--
> >
> >   for(pcb = udp_pcbs; pcb != NULL; pcb = pcb->next) {
> >       ...
> >     }
> > #if (LWIP_DHCP > 0)
> >     // pcb that accepts DHCP msg from DHCP server port?
> >     if((pcb->local_port == udphdr->dest) && (udphdr->src ==
> > DHCP_SERVER_PORT))
> >     {
> >       return;
> >     }
> > #endif
> >   }
> >
> > --end--

> Is this really necessary? The DHCP client should have a UDP PCB in the
list
> anyway (with the IP addresses left unspecified, i.e.,
ip_addr_isany(pcb->ips)
> == 1).
>
You are right. The above code, is not needed.

I used:

udp_bind(state->pcb, IP_ADDR_ANY, DHCP_CLIENT_PORT);
udp_connect(state->pcb, IP_ADDR_ANY, DHCP_SERVER_PORT);

the problem is, IP_ADDR_ANY is defined 0, interpreted NULL by
udp_connect, and so, not set. It remains the old value.

#define IP_ADDR_ANY 0
#define IP_ADDR_BROADCAST (&ip_addr_broadcast)

So, what is a neat way of connecting an udp_pcb to IP_ADDR_ANY,

Would #define IP_ADDR_BROADCAST (&ip_addr_any) do the
trick nicely, or should I do a ip_set_addr on the
destination address of the udp?

Also, as a small sidenote, I found it confusing having
pcb->local_* and pcb->dest_*.

More appropriate are pcb->local_* and pcb->remote_* which
are location based identifiers. dest and src are always
respective to a communication direction.

Regards, Leon.


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