lib/ll_map.c

   1 /*
   2  * ll_map.c
   3  *
   4  *              This program is free software; you can redistribute it and/or
   5  *              modify it under the terms of the GNU General Public License
   6  *              as published by the Free Software Foundation; either version
   7  *              2 of the License, or (at your option) any later version.
   8  *
   9  * Authors:     Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
  10  *
  11  */
  12
  13 #include <stdio.h>
  14 #include <stdlib.h>
  15 #include <unistd.h>
  16 #include <fcntl.h>
  17 #include <sys/socket.h>
  18 #include <netinet/in.h>
  19 #include <string.h>
  20 #include <net/if.h>
  21
  22 #include "libnetlink.h"
  23 #include "ll_map.h"
  24 #include "list.h"
  25
  26 struct ll_cache {
  27         struct hlist_node idx_hash;
  28         struct hlist_node name_hash;
  29         unsigned        flags;
  30         unsigned        index;
  31         unsigned short  type;
  32         char            name[];
  33 };
  34
  35 #define IDXMAP_SIZE     1024
  36 static struct hlist_head idx_head[IDXMAP_SIZE];
  37 static struct hlist_head name_head[IDXMAP_SIZE];
  38
  39 static struct ll_cache *ll_get_by_index(unsigned index)
  40 {
  41         struct hlist_node *n;
  42         unsigned h = index & (IDXMAP_SIZE - 1);
  43
  44         hlist_for_each(n, &idx_head[h]) {
  45                 struct ll_cache *im
  46                         = container_of(n, struct ll_cache, idx_hash);
  47                 if (im->index == index)
  48                         return im;
  49         }
  50
  51         return NULL;
  52 }
  53
  54 unsigned namehash(const char *str)
  55 {
  56         unsigned hash = 5381;
  57
  58         while (*str)
  59                 hash = ((hash << 5) + hash) + *str++; /* hash * 33 + c */
  60
  61         return hash;
  62 }
  63
  64 static struct ll_cache *ll_get_by_name(const char *name)
  65 {
  66         struct hlist_node *n;
  67         unsigned h = namehash(name) & (IDXMAP_SIZE - 1);
  68
  69         hlist_for_each(n, &name_head[h]) {
  70                 struct ll_cache *im
  71                         = container_of(n, struct ll_cache, name_hash);
  72
  73                 if (strncmp(im->name, name, IFNAMSIZ) == 0)
  74                         return im;
  75         }
  76
  77         return NULL;
  78 }
  79
  80 int ll_remember_index(struct nlmsghdr *n, void *arg)
  81 {
  82         unsigned int h;
  83         const char *ifname;
  84         struct ifinfomsg *ifi = NLMSG_DATA(n);
  85         struct ll_cache *im;
  86         struct rtattr *tb[IFLA_MAX+1];
  87
  88         if (n->nlmsg_type != RTM_NEWLINK && n->nlmsg_type != RTM_DELLINK)
  89                 return 0;
  90
  91         if (n->nlmsg_len < NLMSG_LENGTH(sizeof(*ifi)))
  92                 return -1;
  93
  94         im = ll_get_by_index(ifi->ifi_index);
  95         if (n->nlmsg_type == RTM_DELLINK) {
  96                 if (im) {
  97                         hlist_del(&im->name_hash);
  98                         hlist_del(&im->idx_hash);
  99                         free(im);
 100                 }
 101                 return 0;
 102         }
 103
 104         parse_rtattr(tb, IFLA_MAX, IFLA_RTA(ifi), IFLA_PAYLOAD(n));
 105         ifname = rta_getattr_str(tb[IFLA_IFNAME]);
 106         if (ifname == NULL)
 107                 return 0;
 108
 109         if (im) {
 110                 /* change to existing entry */
 111                 if (strcmp(im->name, ifname) != 0) {
 112                         hlist_del(&im->name_hash);
 113                         h = namehash(ifname) & (IDXMAP_SIZE - 1);
 114                         hlist_add_head(&im->name_hash, &name_head[h]);
 115                 }
 116
 117                 im->flags = ifi->ifi_flags;
 118                 return 0;
 119         }
 120
 121         im = malloc(sizeof(*im) + strlen(ifname) + 1);
 122         if (im == NULL)
 123                 return 0;
 124         im->index = ifi->ifi_index;
 125         strcpy(im->name, ifname);
 126         im->type = ifi->ifi_type;
 127         im->flags = ifi->ifi_flags;
 128
 129         h = ifi->ifi_index & (IDXMAP_SIZE - 1);
 130         hlist_add_head(&im->idx_hash, &idx_head[h]);
 131
 132         h = namehash(ifname) & (IDXMAP_SIZE - 1);
 133         hlist_add_head(&im->name_hash, &name_head[h]);
 134
 135         return 0;
 136 }
 137
 138 const char *ll_idx_n2a(unsigned int idx)
 139 {
 140         static char buf[IFNAMSIZ];
 141
 142         snprintf(buf, sizeof(buf), "if%u", idx);
 143         return buf;
 144 }
 145
 146 static unsigned int ll_idx_a2n(const char *name)
 147 {
 148         unsigned int idx;
 149
 150         if (sscanf(name, "if%u", &idx) != 1)
 151                 return 0;
 152         return idx;
 153 }
 154
 155 static int ll_link_get(const char *name, int index)
 156 {
 157         struct {
 158                 struct nlmsghdr         n;
 159                 struct ifinfomsg        ifm;
 160                 char                    buf[1024];
 161         } req = {
 162                 .n.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifinfomsg)),
 163                 .n.nlmsg_flags = NLM_F_REQUEST,
 164                 .n.nlmsg_type = RTM_GETLINK,
 165                 .ifm.ifi_index = index,
 166         };
 167         __u32 filt_mask = RTEXT_FILTER_VF | RTEXT_FILTER_SKIP_STATS;
 168         struct rtnl_handle rth = {};
 169         struct nlmsghdr *answer;
 170         int rc = 0;
 171
 172         if (rtnl_open(&rth, 0) < 0)
 173                 return 0;
 174
 175         addattr32(&req.n, sizeof(req), IFLA_EXT_MASK, filt_mask);
 176         if (name)
 177                 addattr_l(&req.n, sizeof(req), IFLA_IFNAME, name,
 178                           strlen(name) + 1);
 179
 180         if (rtnl_talk(&rth, &req.n, &answer) < 0)
 181                 goto out;
 182
 183         /* add entry to cache */
 184         rc  = ll_remember_index(answer, NULL);
 185         if (!rc) {
 186                 struct ifinfomsg *ifm = NLMSG_DATA(answer);
 187
 188                 rc = ifm->ifi_index;
 189         }
 190
 191         free(answer);
 192 out:
 193         rtnl_close(&rth);
 194         return rc;
 195 }
 196
 197 const char *ll_index_to_name(unsigned int idx)
 198 {
 199         static char buf[IFNAMSIZ];
 200         const struct ll_cache *im;
 201
 202         if (idx == 0)
 203                 return "*";
 204
 205         im = ll_get_by_index(idx);
 206         if (im)
 207                 return im->name;
 208
 209         if (ll_link_get(NULL, idx) == idx) {
 210                 im = ll_get_by_index(idx);
 211                 if (im)
 212                         return im->name;
 213         }
 214
 215         if (if_indextoname(idx, buf) == NULL)
 216                 snprintf(buf, IFNAMSIZ, "if%u", idx);
 217
 218         return buf;
 219 }
 220
 221 int ll_index_to_type(unsigned idx)
 222 {
 223         const struct ll_cache *im;
 224
 225         if (idx == 0)
 226                 return -1;
 227
 228         im = ll_get_by_index(idx);
 229         return im ? im->type : -1;
 230 }
 231
 232 int ll_index_to_flags(unsigned idx)
 233 {
 234         const struct ll_cache *im;
 235
 236         if (idx == 0)
 237                 return 0;
 238
 239         im = ll_get_by_index(idx);
 240         return im ? im->flags : -1;
 241 }
 242
 243 unsigned ll_name_to_index(const char *name)
 244 {
 245         const struct ll_cache *im;
 246         unsigned idx;
 247
 248         if (name == NULL)
 249                 return 0;
 250
 251         im = ll_get_by_name(name);
 252         if (im)
 253                 return im->index;
 254
 255         idx = ll_link_get(name, 0);
 256         if (idx == 0)
 257                 idx = if_nametoindex(name);
 258         if (idx == 0)
 259                 idx = ll_idx_a2n(name);
 260         return idx;
 261 }
 262
 263 void ll_drop_by_index(unsigned index)
 264 {
 265         struct ll_cache *im;
 266
 267         im = ll_get_by_index(index);
 268         if (!im)
 269                 return;
 270
 271         hlist_del(&im->idx_hash);
 272         hlist_del(&im->name_hash);
 273
 274         free(im);
 275 }
 276
 277 void ll_init_map(struct rtnl_handle *rth)
 278 {
 279         static int initialized;
 280
 281         if (initialized)
 282                 return;
 283
 284         if (rtnl_linkdump_req(rth, AF_UNSPEC) < 0) {
 285                 perror("Cannot send dump request");
 286                 exit(1);
 287         }
 288
 289         if (rtnl_dump_filter(rth, ll_remember_index, NULL) < 0) {
 290                 fprintf(stderr, "Dump terminated\n");
 291                 exit(1);
 292         }
 293
 294         initialized = 1;
 295 }