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} 115