src/libsystemd-network/sd-ipv4ll.c

   1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
   2 /***
   3   Copyright © 2014 Axis Communications AB. All rights reserved.
   4 ***/
   5
   6 #include <arpa/inet.h>
   7 #include <errno.h>
   8 #include <stdio.h>
   9 #include <stdlib.h>
  10
  11 #include "sd-id128.h"
  12 #include "sd-ipv4acd.h"
  13 #include "sd-ipv4ll.h"
  14
  15 #include "alloc-util.h"
  16 #include "ether-addr-util.h"
  17 #include "in-addr-util.h"
  18 #include "log-link.h"
  19 #include "random-util.h"
  20 #include "siphash24.h"
  21 #include "sparse-endian.h"
  22 #include "string-util.h"
  23 #include "util.h"
  24
  25 #define IPV4LL_NETWORK UINT32_C(0xA9FE0000)
  26 #define IPV4LL_NETMASK UINT32_C(0xFFFF0000)
  27
  28 #define IPV4LL_DONT_DESTROY(ll) \
  29         _cleanup_(sd_ipv4ll_unrefp) _unused_ sd_ipv4ll *_dont_destroy_##ll = sd_ipv4ll_ref(ll)
  30
  31 struct sd_ipv4ll {
  32         unsigned n_ref;
  33
  34         sd_ipv4acd *acd;
  35
  36         be32_t address; /* the address pushed to ACD */
  37         struct ether_addr mac;
  38
  39         struct {
  40                 le64_t value;
  41                 le64_t generation;
  42         } seed;
  43         bool seed_set;
  44
  45         /* External */
  46         be32_t claimed_address;
  47
  48         sd_ipv4ll_callback_t callback;
  49         void *userdata;
  50
  51         sd_ipv4ll_check_mac_callback_t check_mac_callback;
  52         void *check_mac_userdata;
  53 };
  54
  55 #define log_ipv4ll_errno(ll, error, fmt, ...)           \
  56         log_interface_prefix_full_errno(                \
  57                 "IPv4LL: ",                             \
  58                 sd_ipv4ll_get_ifname(ll),               \
  59                 error, fmt, ##__VA_ARGS__)
  60 #define log_ipv4ll(ll, fmt, ...)                        \
  61         log_interface_prefix_full_errno_zerook(         \
  62                 "IPv4LL: ",                             \
  63                 sd_ipv4ll_get_ifname(ll),               \
  64                 0, fmt, ##__VA_ARGS__)
  65
  66 static void ipv4ll_on_acd(sd_ipv4acd *acd, int event, void *userdata);
  67 static int ipv4ll_check_mac(sd_ipv4acd *acd, const struct ether_addr *mac, void *userdata);
  68
  69 static sd_ipv4ll *ipv4ll_free(sd_ipv4ll *ll) {
  70         assert(ll);
  71
  72         sd_ipv4acd_unref(ll->acd);
  73         return mfree(ll);
  74 }
  75
  76 DEFINE_TRIVIAL_REF_UNREF_FUNC(sd_ipv4ll, sd_ipv4ll, ipv4ll_free);
  77
  78 int sd_ipv4ll_new(sd_ipv4ll **ret) {
  79         _cleanup_(sd_ipv4ll_unrefp) sd_ipv4ll *ll = NULL;
  80         int r;
  81
  82         assert_return(ret, -EINVAL);
  83
  84         ll = new0(sd_ipv4ll, 1);
  85         if (!ll)
  86                 return -ENOMEM;
  87
  88         ll->n_ref = 1;
  89
  90         r = sd_ipv4acd_new(&ll->acd);
  91         if (r < 0)
  92                 return r;
  93
  94         r = sd_ipv4acd_set_callback(ll->acd, ipv4ll_on_acd, ll);
  95         if (r < 0)
  96                 return r;
  97
  98         r = sd_ipv4acd_set_check_mac_callback(ll->acd, ipv4ll_check_mac, ll);
  99         if (r < 0)
 100                 return r;
 101
 102         *ret = TAKE_PTR(ll);
 103
 104         return 0;
 105 }
 106
 107 int sd_ipv4ll_stop(sd_ipv4ll *ll) {
 108         if (!ll)
 109                 return 0;
 110
 111         return sd_ipv4acd_stop(ll->acd);
 112 }
 113
 114 int sd_ipv4ll_set_ifindex(sd_ipv4ll *ll, int ifindex) {
 115         assert_return(ll, -EINVAL);
 116         assert_return(ifindex > 0, -EINVAL);
 117         assert_return(sd_ipv4ll_is_running(ll) == 0, -EBUSY);
 118
 119         return sd_ipv4acd_set_ifindex(ll->acd, ifindex);
 120 }
 121
 122 int sd_ipv4ll_get_ifindex(sd_ipv4ll *ll) {
 123         if (!ll)
 124                 return -EINVAL;
 125
 126         return sd_ipv4acd_get_ifindex(ll->acd);
 127 }
 128
 129 int sd_ipv4ll_set_ifname(sd_ipv4ll *ll, const char *ifname) {
 130         assert_return(ll, -EINVAL);
 131         assert_return(ifname, -EINVAL);
 132
 133         return sd_ipv4acd_set_ifname(ll->acd, ifname);
 134 }
 135
 136 const char *sd_ipv4ll_get_ifname(sd_ipv4ll *ll) {
 137         if (!ll)
 138                 return NULL;
 139
 140         return sd_ipv4acd_get_ifname(ll->acd);
 141 }
 142
 143 int sd_ipv4ll_set_mac(sd_ipv4ll *ll, const struct ether_addr *addr) {
 144         int r;
 145
 146         assert_return(ll, -EINVAL);
 147         assert_return(addr, -EINVAL);
 148         assert_return(!ether_addr_is_null(addr), -EINVAL);
 149
 150         r = sd_ipv4acd_set_mac(ll->acd, addr);
 151         if (r < 0)
 152                 return r;
 153
 154         ll->mac = *addr;
 155         return 0;
 156 }
 157
 158 int sd_ipv4ll_detach_event(sd_ipv4ll *ll) {
 159         assert_return(ll, -EINVAL);
 160
 161         return sd_ipv4acd_detach_event(ll->acd);
 162 }
 163
 164 int sd_ipv4ll_attach_event(sd_ipv4ll *ll, sd_event *event, int64_t priority) {
 165         assert_return(ll, -EINVAL);
 166
 167         return sd_ipv4acd_attach_event(ll->acd, event, priority);
 168 }
 169
 170 int sd_ipv4ll_set_callback(sd_ipv4ll *ll, sd_ipv4ll_callback_t cb, void *userdata) {
 171         assert_return(ll, -EINVAL);
 172
 173         ll->callback = cb;
 174         ll->userdata = userdata;
 175
 176         return 0;
 177 }
 178
 179 int sd_ipv4ll_set_check_mac_callback(sd_ipv4ll *ll, sd_ipv4ll_check_mac_callback_t cb, void *userdata) {
 180         assert_return(ll, -EINVAL);
 181
 182         ll->check_mac_callback = cb;
 183         ll->check_mac_userdata = userdata;
 184
 185         return 0;
 186 }
 187
 188 int sd_ipv4ll_get_address(sd_ipv4ll *ll, struct in_addr *address) {
 189         assert_return(ll, -EINVAL);
 190         assert_return(address, -EINVAL);
 191
 192         if (ll->claimed_address == 0)
 193                 return -ENOENT;
 194
 195         address->s_addr = ll->claimed_address;
 196
 197         return 0;
 198 }
 199
 200 int sd_ipv4ll_set_address_seed(sd_ipv4ll *ll, uint64_t seed) {
 201         assert_return(ll, -EINVAL);
 202         assert_return(sd_ipv4ll_is_running(ll) == 0, -EBUSY);
 203
 204         ll->seed.value = htole64(seed);
 205         ll->seed_set = true;
 206
 207         return 0;
 208 }
 209
 210 int sd_ipv4ll_is_running(sd_ipv4ll *ll) {
 211         assert_return(ll, false);
 212
 213         return sd_ipv4acd_is_running(ll->acd);
 214 }
 215
 216 static bool ipv4ll_address_is_valid(const struct in_addr *address) {
 217         assert(address);
 218
 219         if (!in4_addr_is_link_local(address))
 220                 return false;
 221
 222         return !IN_SET(be32toh(address->s_addr) & 0x0000FF00U, 0x0000U, 0xFF00U);
 223 }
 224
 225 int sd_ipv4ll_set_address(sd_ipv4ll *ll, const struct in_addr *address) {
 226         int r;
 227
 228         assert_return(ll, -EINVAL);
 229         assert_return(address, -EINVAL);
 230         assert_return(ipv4ll_address_is_valid(address), -EINVAL);
 231
 232         r = sd_ipv4acd_set_address(ll->acd, address);
 233         if (r < 0)
 234                 return r;
 235
 236         ll->address = address->s_addr;
 237
 238         return 0;
 239 }
 240
 241 #define PICK_HASH_KEY SD_ID128_MAKE(15,ac,82,a6,d6,3f,49,78,98,77,5d,0c,69,02,94,0b)
 242
 243 static int ipv4ll_pick_address(sd_ipv4ll *ll) {
 244         _cleanup_free_ char *address = NULL;
 245         be32_t addr;
 246
 247         assert(ll);
 248
 249         do {
 250                 uint64_t h;
 251
 252                 h = siphash24(&ll->seed, sizeof(ll->seed), PICK_HASH_KEY.bytes);
 253
 254                 /* Increase the generation counter by one */
 255                 ll->seed.generation = htole64(le64toh(ll->seed.generation) + 1);
 256
 257                 addr = htobe32((h & UINT32_C(0x0000FFFF)) | IPV4LL_NETWORK);
 258         } while (addr == ll->address ||
 259                  IN_SET(be32toh(addr) & 0x0000FF00U, 0x0000U, 0xFF00U));
 260
 261         (void) in_addr_to_string(AF_INET, &(union in_addr_union) { .in.s_addr = addr }, &address);
 262         log_ipv4ll(ll, "Picked new IP address %s.", strna(address));
 263
 264         return sd_ipv4ll_set_address(ll, &(struct in_addr) { addr });
 265 }
 266
 267 #define MAC_HASH_KEY SD_ID128_MAKE(df,04,22,98,3f,ad,14,52,f9,87,2e,d1,9c,70,e2,f2)
 268
 269 static int ipv4ll_start_internal(sd_ipv4ll *ll, bool reset_generation) {
 270         int r;
 271         bool picked_address = false;
 272
 273         assert_return(ll, -EINVAL);
 274         assert_return(!ether_addr_is_null(&ll->mac), -EINVAL);
 275
 276         /* If no random seed is set, generate some from the MAC address */
 277         if (!ll->seed_set)
 278                 ll->seed.value = htole64(siphash24(ll->mac.ether_addr_octet, ETH_ALEN, MAC_HASH_KEY.bytes));
 279
 280         if (reset_generation)
 281                 ll->seed.generation = 0;
 282
 283         if (ll->address == 0) {
 284                 r = ipv4ll_pick_address(ll);
 285                 if (r < 0)
 286                         return r;
 287
 288                 picked_address = true;
 289         }
 290
 291         r = sd_ipv4acd_start(ll->acd, reset_generation);
 292         if (r < 0) {
 293
 294                 /* We couldn't start? If so, let's forget the picked address again, the user might make a change and
 295                  * retry, and we want the new data to take effect when picking an address. */
 296                 if (picked_address)
 297                         ll->address = 0;
 298
 299                 return r;
 300         }
 301
 302         return 1;
 303 }
 304
 305 int sd_ipv4ll_start(sd_ipv4ll *ll) {
 306         assert_return(ll, -EINVAL);
 307
 308         if (sd_ipv4ll_is_running(ll))
 309                 return 0;
 310
 311         return ipv4ll_start_internal(ll, true);
 312 }
 313
 314 int sd_ipv4ll_restart(sd_ipv4ll *ll) {
 315         ll->address = 0;
 316
 317         return ipv4ll_start_internal(ll, false);
 318 }
 319
 320 static void ipv4ll_client_notify(sd_ipv4ll *ll, int event) {
 321         assert(ll);
 322
 323         if (ll->callback)
 324                 ll->callback(ll, event, ll->userdata);
 325 }
 326
 327 void ipv4ll_on_acd(sd_ipv4acd *acd, int event, void *userdata) {
 328         sd_ipv4ll *ll = userdata;
 329         IPV4LL_DONT_DESTROY(ll);
 330         int r;
 331
 332         assert(acd);
 333         assert(ll);
 334
 335         switch (event) {
 336
 337         case SD_IPV4ACD_EVENT_STOP:
 338                 ipv4ll_client_notify(ll, SD_IPV4LL_EVENT_STOP);
 339                 ll->claimed_address = 0;
 340                 break;
 341
 342         case SD_IPV4ACD_EVENT_BIND:
 343                 ll->claimed_address = ll->address;
 344                 ipv4ll_client_notify(ll, SD_IPV4LL_EVENT_BIND);
 345                 break;
 346
 347         case SD_IPV4ACD_EVENT_CONFLICT:
 348                 /* if an address was already bound we must call up to the
 349                    user to handle this, otherwise we just try again */
 350                 if (ll->claimed_address != 0) {
 351                         ipv4ll_client_notify(ll, SD_IPV4LL_EVENT_CONFLICT);
 352
 353                         ll->claimed_address = 0;
 354                 } else {
 355                         r = sd_ipv4ll_restart(ll);
 356                         if (r < 0)
 357                                 goto error;
 358                 }
 359
 360                 break;
 361
 362         default:
 363                 assert_not_reached();
 364         }
 365
 366         return;
 367
 368 error:
 369         ipv4ll_client_notify(ll, SD_IPV4LL_EVENT_STOP);
 370 }
 371
 372 static int ipv4ll_check_mac(sd_ipv4acd *acd, const struct ether_addr *mac, void *userdata) {
 373         sd_ipv4ll *ll = userdata;
 374
 375         assert(ll);
 376
 377         if (ll->check_mac_callback)
 378                 return ll->check_mac_callback(ll, mac, ll->check_mac_userdata);
 379
 380         return 0;
 381 }