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#define _GNU_SOURCE
#include <net/if.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <errno.h>
#include "syscall.h"
#include <stdio.h>
static void *do_nameindex(int s, size_t n)
{
size_t i, len;
struct ifconf conf;
struct if_nameindex *idx;
idx = malloc(n * (sizeof(struct if_nameindex)+sizeof(struct ifreq)));
if (!idx) return 0;
conf.ifc_buf = (void *)&idx[n];
conf.ifc_len = len = n * sizeof(struct ifreq);
if (ioctl(s, SIOCGIFCONF, &conf) < 0) {
free(idx);
return 0;
}
if (conf.ifc_len == len) {
free(idx);
return (void *)-1;
}
n = conf.ifc_len / sizeof(struct ifreq);
for (i=0; i<n; i++) {
if (ioctl(s, SIOCGIFINDEX, &conf.ifc_req[i]) < 0) {
i--;
n--;
continue;
}
idx[i].if_index = conf.ifc_req[i].ifr_ifindex;
idx[i].if_name = conf.ifc_req[i].ifr_name;
}
idx[i].if_name = 0;
idx[i].if_index = 0;
return idx;
}
struct if_nameindex *if_nameindex()
{
size_t n;
void *p = 0;
int s = socket(AF_UNIX, SOCK_DGRAM, 0);
if (s>=0) {
for (n=0; (p=do_nameindex(s, n)) == (void *)-1; n++);
__syscall(SYS_close, s);
}
errno = ENOBUFS;
return p;
}
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