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