c - How to find out if the eth0 mode is static or dhcp? -

i want use c program if ip of network interface set manually or via dhcp.

i've tried use following code , has worked in debian, hasn't worked in openwrt. want know how write c program doing in openwrt. have tried use this:

#include <stdio.h> int main(void) {     file *fp;     char buffer[80];     fp=popen("cat /etc/network/interfaces |grep ^iface\\ br-lan | awk -f ' ' '{print $4}'","r");     fgets(buffer, sizeof(buffer), fp);     printf("%s", buffer);     pclose(fp); } 

this code working in debian, isn't working in openwrt, want know how write program same result.

for openwrt can such information following command:

$uci network.lan.proto 

so take program put in question , change command used information:

#include <stdio.h> <br> int main(void) {     file *fp;     char buffer[80];     fp=popen("uci network.lan.proto","r");     fgets(buffer, sizeof(buffer), fp);     printf("%s", buffer);     pclose(fp); } 

to see network interfaces available in openwrt can use following command:

$uci show network 

you can avoid using calling linux command in c using libuci. libuci contains c function execute uci commands without passing via popen ( popen used execute external command shell).

the libuci exist default in development environment of openwrt, not need download it, no need build , no need install on openwrt machine

you can use libuci in way

#include <uci.h> void main() {     char path[]="network.lan.proto";     char buffer[80];     struct  uci_ptr ptr;     struct  uci_context *c = uci_alloc_context();      if(!c) return;      if ((uci_lookup_ptr(c, &ptr, path, true) != uci_ok) ||         (ptr.o==null || ptr.o->v.string==null)) {          uci_free_context(c);         return;     }      if(ptr.flags & uci_lookup_complete)             strcpy(buffer, ptr.o->v.string);      uci_free_context(c);      printf("%s\n", buffer); } 

(not tested)

and when compile program have add -luci in compilation command gcc