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#include <net/if.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>
#include <sys/ioctl.h>
#include <stdio.h>
struct if_nameindex* if_nameindex(void) {
struct ifconf ic;
int fd,len,i;
struct if_nameindex* x,* y;
char *dest;
fd=socket(AF_INET6,SOCK_DGRAM,0);
if (fd<0) fd=socket(AF_INET,SOCK_DGRAM,0);
ic.ifc_buf=0;
ic.ifc_len=0;
if (ioctl(fd,SIOCGIFCONF,&ic)<0) {
b0rken:
close(fd);
return 0;
}
ic.ifc_buf=alloca((size_t)ic.ifc_len);
if (ioctl(fd,SIOCGIFCONF,&ic)<0) goto b0rken;
len=(ic.ifc_len/sizeof(struct ifreq));
x=(struct if_nameindex*)malloc((len+1)*sizeof(struct if_nameindex)+len*IFNAMSIZ);
if (!x) goto b0rken;
dest=(char*)(x+len+1);
y=x;
for (i=0; i<len; ++i) {
struct ifreq* ir=(struct ifreq*)&ic.ifc_req[i];
y->if_name=dest;
memcpy(dest,ir->ifr_name,IFNAMSIZ);
if (ioctl(fd,SIOCGIFINDEX,ir)==-1) continue;
y->if_index=ir->ifr_ifindex;
dest+=IFNAMSIZ;
++y;
}
y->if_name=0; y->if_index=0;
return x;
}
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