[lwip-users] A better way to switch between static IP and DHCP?

[Xun Chen]

Somehow my lwip user forum subscription/setting/options was not functioning properly, and I may have sent out this request multiple times since I tried to figure out what was wrong. My apologies if it was the case...


Hi there,

The following test was based on lwip 1.41 port on TI's TiVaware

With #define LWIP_DHCP 1 & #define LWIP_AUTOIP 1 in lwipopts.h, I have
no problem using DHCP

    lwIPInit(g_ui32SysClock, pui8MACArray, 0, 0, 0, IPADDR_USE_DHCP);

With #define LWIP_DHCP 0 & #define LWIP_AUTOIP 0 in lwipopts.h, I also
have no problem using static IP

    lwIPInit(g_ui32SysClock, pui8MACArray, inet_addr("55.0.168.192"), inet_addr("0.255.255.255"), inet_addr("1.0.168.192"),  IPADDR_USE_STATIC); 
    //The IP address was in a reversed order, but it works

But if I wish to have both DHCP and Static IP feature, switching between
them based on user configuration, I couldn't make it work without
modifying lwiplib.c, ie. if I make

lwipopts.h:
#define LWIP_DHCP 1
#define LWIP_AUTOIP 1

....
if (USER_NEEDS_DHCP){
    lwIPInit(g_ui32SysClock, pui8MACArray, 0, 0, 0, IPADDR_USE_DHCP);
    //This works
}
else{
    lwIPInit(g_ui32SysClock, pui8MACArray, inet_addr("55.0.168.192"), inet_addr("0.255.255.255"), inet_addr("1.0.168.192"), IPADDR_USE_STATIC);
}

Static IP will not work

I am sure I can modify lwiplib.c based on LWIP_DHCP and LWIP_AUTOIP conditions to make it work, but is there a better way to get the job done?

Thanks!