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| | #define _GNU_SOURCE
#include <net/if.h>
#include <errno.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include "netlink.h"
#define IFADDRS_HASH_SIZE 64
struct ifnamemap {
unsigned int hash_next;
unsigned int index;
unsigned char namelen;
char name[IFNAMSIZ];
};
struct ifnameindexctx {
unsigned int num, allocated, str_bytes;
struct ifnamemap *list;
unsigned int hash[IFADDRS_HASH_SIZE];
};
static int netlink_msg_to_nameindex(void *pctx, struct nlmsghdr *h)
{
struct ifnameindexctx *ctx = pctx;
struct ifnamemap *map;
struct rtattr *rta;
unsigned int i;
int index, type, namelen, bucket;
if (h->nlmsg_type == RTM_NEWLINK) {
struct ifinfomsg *ifi = NLMSG_DATA(h);
index = ifi->ifi_index;
type = IFLA_IFNAME;
rta = NLMSG_RTA(h, sizeof(*ifi));
} else {
struct ifaddrmsg *ifa = NLMSG_DATA(h);
index = ifa->ifa_index;
type = IFA_LABEL;
rta = NLMSG_RTA(h, sizeof(*ifa));
}
for (; NLMSG_RTAOK(rta, h); rta = RTA_NEXT(rta)) {
if (rta->rta_type != type) continue;
namelen = RTA_DATALEN(rta) - 1;
if (namelen > IFNAMSIZ) return 0;
/* suppress duplicates */
bucket = index % IFADDRS_HASH_SIZE;
i = ctx->hash[bucket];
while (i) {
map = &ctx->list[i-1];
if (map->index == index &&
map->namelen == namelen &&
memcmp(map->name, RTA_DATA(rta), namelen) == 0)
return 0;
i = map->hash_next;
}
if (ctx->num >= ctx->allocated) {
size_t a = ctx->allocated ? ctx->allocated * 2 + 1 : 8;
if (a > SIZE_MAX/sizeof *map) return -1;
map = realloc(ctx->list, a * sizeof *map);
if (!map) return -1;
ctx->list = map;
ctx->allocated = a;
}
map = &ctx->list[ctx->num];
map->index = index;
map->namelen = namelen;
memcpy(map->name, RTA_DATA(rta), namelen);
ctx->str_bytes += namelen + 1;
ctx->num++;
map->hash_next = ctx->hash[bucket];
ctx->hash[bucket] = ctx->num;
return 0;
}
return 0;
}
struct if_nameindex *if_nameindex()
{
struct ifnameindexctx _ctx, *ctx = &_ctx;
struct if_nameindex *ifs = 0, *d;
struct ifnamemap *s;
char *p;
int i;
memset(ctx, 0, sizeof(*ctx));
if (__rtnetlink_enumerate(AF_UNSPEC, AF_INET, netlink_msg_to_nameindex, ctx) < 0) goto err;
ifs = malloc(sizeof(struct if_nameindex[ctx->num+1]) + ctx->str_bytes);
if (!ifs) goto err;
p = (char*)(ifs + ctx->num + 1);
for (i = ctx->num, d = ifs, s = ctx->list; i; i--, s++, d++) {
d->if_index = s->index;
d->if_name = p;
memcpy(p, s->name, s->namelen);
p += s->namelen;
*p++ = 0;
}
d->if_index = 0;
d->if_name = 0;
err:
free(ctx->list);
return ifs;
}
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