Re: [lwip-users] DHCP Client (urgent)

[Fabian Koch]

> Please, could give me more details?
> I'm using netconn API.

No difference. The Netif-API is for handling network
interfaces. As far as I can see, it works no matter what API you use for
data-transfer (Raw, netconn, sockets).

In your current project you probably have some global
handle for your network interface (netif*).
You do a netif_add(netif, ip, mask, gateway, state,
init, input).

The new part would be an optional netif_set_status_callback(netif,
callback) where "callback" is a void functiond with a netif*
parameter.
This will be called on a status change of the networkinterface
(going up, down, etc).
Then a simple netifapi_dhcp_start(netif) is enough
to start the DHCP process in the stack/a new task.
When this returns, the DHCP process is not yet finished
but simply started successfully. So I create a Task that waits for DHCP
to finish using an Event/sempahore: if(EventWait(dhcpEvent, timeout) ==
FALSE).
When this times out, I stop the DHCP processing with
netifapi_dhcp_stop(netif)
and use a fixed IP for the interface.
My callback function looks like this:

if(netif->flags
& NETIF_FLAG_UP){
  if(netif->flags
& NETIF_FLAG_DHCP){
    if(dhcpEvent){
      if(netif->dhcp){
        if((ip_addr
*) &(netif->ip_addr)
!= IP_ADDR_ANY){
         
EventSet(dhcpEvent);

meaning, when the status callback hits, I check if
the DHCP process was successful and if so I set my semaphore/Event to stop
the timeout in the other Task.

Not much more to it. You need to have DHCP active
in your lwipopts.h of course. Other than that... should be straight forward.

kind regards,
Fabian