1#define _GNU_SOURCE
2#include <net/if.h>
3#include <errno.h>
4#include <unistd.h>
5#include <stdlib.h>
6#include <string.h>
7#include <pthread.h>
8#include "netlink.h"
9
10#define IFADDRS_HASH_SIZE 64
11
12struct ifnamemap {
13 unsigned int hash_next;
14 unsigned int index;
15 unsigned char namelen;
16 char name[IFNAMSIZ];
17};
18
19struct ifnameindexctx {
20 unsigned int num, allocated, str_bytes;
21 struct ifnamemap *list;
22 unsigned int hash[IFADDRS_HASH_SIZE];
23};
24
25static int netlink_msg_to_nameindex(void *pctx, struct nlmsghdr *h)
26{
27 struct ifnameindexctx *ctx = pctx;
28 struct ifnamemap *map;
29 struct rtattr *rta;
30 unsigned int i;
31 int index, type, namelen, bucket;
32
33 if (h->nlmsg_type == RTM_NEWLINK) {
34 struct ifinfomsg *ifi = NLMSG_DATA(h);
35 index = ifi->ifi_index;
36 type = IFLA_IFNAME;
37 rta = NLMSG_RTA(h, sizeof(*ifi));
38 } else {
39 struct ifaddrmsg *ifa = NLMSG_DATA(h);
40 index = ifa->ifa_index;
41 type = IFA_LABEL;
42 rta = NLMSG_RTA(h, sizeof(*ifa));
43 }
44 for (; NLMSG_RTAOK(rta, h); rta = RTA_NEXT(rta)) {
45 if (rta->rta_type != type) continue;
46
47 namelen = RTA_DATALEN(rta) - 1;
48 if (namelen > IFNAMSIZ) return 0;
49
50 /* suppress duplicates */
51 bucket = index % IFADDRS_HASH_SIZE;
52 i = ctx->hash[bucket];
53 while (i) {
54 map = &ctx->list[i-1];
55 if (map->index == index &&
56 map->namelen == namelen &&
57 memcmp(map->name, RTA_DATA(rta), namelen) == 0)
58 return 0;
59 i = map->hash_next;
60 }
61
62 if (ctx->num >= ctx->allocated) {
63 size_t a = ctx->allocated ? ctx->allocated * 2 + 1 : 8;
64 if (a > SIZE_MAX/sizeof *map) return -1;
65 map = realloc(ctx->list, a * sizeof *map);
66 if (!map) return -1;
67 ctx->list = map;
68 ctx->allocated = a;
69 }
70 map = &ctx->list[ctx->num];
71 map->index = index;
72 map->namelen = namelen;
73 memcpy(map->name, RTA_DATA(rta), namelen);
74 ctx->str_bytes += namelen + 1;
75 ctx->num++;
76 map->hash_next = ctx->hash[bucket];
77 ctx->hash[bucket] = ctx->num;
78 return 0;
79 }
80 return 0;
81}
82
83struct if_nameindex *if_nameindex()
84{
85 struct ifnameindexctx _ctx, *ctx = &_ctx;
86 struct if_nameindex *ifs = 0, *d;
87 struct ifnamemap *s;
88 char *p;
89 int i;
90 int cs;
91
92 pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
93 memset(ctx, 0, sizeof(*ctx));
94 if (__rtnetlink_enumerate(AF_UNSPEC, AF_INET, netlink_msg_to_nameindex, ctx) < 0) goto err;
95
96 ifs = malloc(sizeof(struct if_nameindex[ctx->num+1]) + ctx->str_bytes);
97 if (!ifs) goto err;
98
99 p = (char*)(ifs + ctx->num + 1);
100 for (i = ctx->num, d = ifs, s = ctx->list; i; i--, s++, d++) {
101 d->if_index = s->index;
102 d->if_name = p;
103 memcpy(p, s->name, s->namelen);
104 p += s->namelen;
105 *p++ = 0;
106 }
107 d->if_index = 0;
108 d->if_name = 0;
109err:
110 pthread_setcancelstate(cs, 0);
111 free(ctx->list);
112 errno = ENOBUFS;
113 return ifs;
114}