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
  52 #define log_ipv4ll_errno(ll, error, fmt, ...)                           \
  53         log_interface_full_errno(sd_ipv4ll_get_ifname(ll), LOG_DEBUG, error, "IPV4LL: " fmt, ##__VA_ARGS__)
  54 #define log_ipv4ll(ll, fmt, ...)                        \
  55         log_ipv4ll_errno(ll, 0, fmt, ##__VA_ARGS__)
  56
  57 static void ipv4ll_on_acd(sd_ipv4acd *ll, int event, void *userdata);
  58
  59 static sd_ipv4ll *ipv4ll_free(sd_ipv4ll *ll) {
  60         assert(ll);
  61
  62         sd_ipv4acd_unref(ll->acd);
  63         return mfree(ll);
  64 }
  65
  66 DEFINE_TRIVIAL_REF_UNREF_FUNC(sd_ipv4ll, sd_ipv4ll, ipv4ll_free);
  67
  68 int sd_ipv4ll_new(sd_ipv4ll **ret) {
  69         _cleanup_(sd_ipv4ll_unrefp) sd_ipv4ll *ll = NULL;
  70         int r;
  71
  72         assert_return(ret, -EINVAL);
  73
  74         ll = new0(sd_ipv4ll, 1);
  75         if (!ll)
  76                 return -ENOMEM;
  77
  78         ll->n_ref = 1;
  79
  80         r = sd_ipv4acd_new(&ll->acd);
  81         if (r < 0)
  82                 return r;
  83
  84         r = sd_ipv4acd_set_callback(ll->acd, ipv4ll_on_acd, ll);
  85         if (r < 0)
  86                 return r;
  87
  88         *ret = TAKE_PTR(ll);
  89
  90         return 0;
  91 }
  92
  93 int sd_ipv4ll_stop(sd_ipv4ll *ll) {
  94         if (!ll)
  95                 return 0;
  96
  97         return sd_ipv4acd_stop(ll->acd);
  98 }
  99
 100 int sd_ipv4ll_set_ifindex(sd_ipv4ll *ll, int ifindex) {
 101         assert_return(ll, -EINVAL);
 102         assert_return(ifindex > 0, -EINVAL);
 103         assert_return(sd_ipv4ll_is_running(ll) == 0, -EBUSY);
 104
 105         return sd_ipv4acd_set_ifindex(ll->acd, ifindex);
 106 }
 107
 108 int sd_ipv4ll_get_ifindex(sd_ipv4ll *ll) {
 109         if (!ll)
 110                 return -EINVAL;
 111
 112         return sd_ipv4acd_get_ifindex(ll->acd);
 113 }
 114
 115 const char *sd_ipv4ll_get_ifname(sd_ipv4ll *ll) {
 116         if (!ll)
 117                 return NULL;
 118
 119         return sd_ipv4acd_get_ifname(ll->acd);
 120 }
 121
 122 int sd_ipv4ll_set_mac(sd_ipv4ll *ll, const struct ether_addr *addr) {
 123         int r;
 124
 125         assert_return(ll, -EINVAL);
 126         assert_return(addr, -EINVAL);
 127         assert_return(sd_ipv4ll_is_running(ll) == 0, -EBUSY);
 128
 129         r = sd_ipv4acd_set_mac(ll->acd, addr);
 130         if (r < 0)
 131                 return r;
 132
 133         ll->mac = *addr;
 134         return 0;
 135 }
 136
 137 int sd_ipv4ll_detach_event(sd_ipv4ll *ll) {
 138         assert_return(ll, -EINVAL);
 139
 140         return sd_ipv4acd_detach_event(ll->acd);
 141 }
 142
 143 int sd_ipv4ll_attach_event(sd_ipv4ll *ll, sd_event *event, int64_t priority) {
 144         assert_return(ll, -EINVAL);
 145
 146         return sd_ipv4acd_attach_event(ll->acd, event, priority);
 147 }
 148
 149 int sd_ipv4ll_set_callback(sd_ipv4ll *ll, sd_ipv4ll_callback_t cb, void *userdata) {
 150         assert_return(ll, -EINVAL);
 151
 152         ll->callback = cb;
 153         ll->userdata = userdata;
 154
 155         return 0;
 156 }
 157
 158 int sd_ipv4ll_get_address(sd_ipv4ll *ll, struct in_addr *address) {
 159         assert_return(ll, -EINVAL);
 160         assert_return(address, -EINVAL);
 161
 162         if (ll->claimed_address == 0)
 163                 return -ENOENT;
 164
 165         address->s_addr = ll->claimed_address;
 166
 167         return 0;
 168 }
 169
 170 int sd_ipv4ll_set_address_seed(sd_ipv4ll *ll, uint64_t seed) {
 171         assert_return(ll, -EINVAL);
 172         assert_return(sd_ipv4ll_is_running(ll) == 0, -EBUSY);
 173
 174         ll->seed.value = htole64(seed);
 175         ll->seed_set = true;
 176
 177         return 0;
 178 }
 179
 180 int sd_ipv4ll_is_running(sd_ipv4ll *ll) {
 181         assert_return(ll, false);
 182
 183         return sd_ipv4acd_is_running(ll->acd);
 184 }
 185
 186 static bool ipv4ll_address_is_valid(const struct in_addr *address) {
 187         assert(address);
 188
 189         if (!in4_addr_is_link_local(address))
 190                 return false;
 191
 192         return !IN_SET(be32toh(address->s_addr) & 0x0000FF00U, 0x0000U, 0xFF00U);
 193 }
 194
 195 int sd_ipv4ll_set_address(sd_ipv4ll *ll, const struct in_addr *address) {
 196         int r;
 197
 198         assert_return(ll, -EINVAL);
 199         assert_return(address, -EINVAL);
 200         assert_return(ipv4ll_address_is_valid(address), -EINVAL);
 201
 202         r = sd_ipv4acd_set_address(ll->acd, address);
 203         if (r < 0)
 204                 return r;
 205
 206         ll->address = address->s_addr;
 207
 208         return 0;
 209 }
 210
 211 #define PICK_HASH_KEY SD_ID128_MAKE(15,ac,82,a6,d6,3f,49,78,98,77,5d,0c,69,02,94,0b)
 212
 213 static int ipv4ll_pick_address(sd_ipv4ll *ll) {
 214         _cleanup_free_ char *address = NULL;
 215         be32_t addr;
 216
 217         assert(ll);
 218
 219         do {
 220                 uint64_t h;
 221
 222                 h = siphash24(&ll->seed, sizeof(ll->seed), PICK_HASH_KEY.bytes);
 223
 224                 /* Increase the generation counter by one */
 225                 ll->seed.generation = htole64(le64toh(ll->seed.generation) + 1);
 226
 227                 addr = htobe32((h & UINT32_C(0x0000FFFF)) | IPV4LL_NETWORK);
 228         } while (addr == ll->address ||
 229                  IN_SET(be32toh(addr) & 0x0000FF00U, 0x0000U, 0xFF00U));
 230
 231         (void) in_addr_to_string(AF_INET, &(union in_addr_union) { .in.s_addr = addr }, &address);
 232         log_ipv4ll(ll, "Picked new IP address %s.", strna(address));
 233
 234         return sd_ipv4ll_set_address(ll, &(struct in_addr) { addr });
 235 }
 236
 237 #define MAC_HASH_KEY SD_ID128_MAKE(df,04,22,98,3f,ad,14,52,f9,87,2e,d1,9c,70,e2,f2)
 238
 239 static int ipv4ll_start_internal(sd_ipv4ll *ll, bool reset_generation) {
 240         int r;
 241         bool picked_address = false;
 242
 243         assert_return(ll, -EINVAL);
 244         assert_return(!ether_addr_is_null(&ll->mac), -EINVAL);
 245
 246         /* If no random seed is set, generate some from the MAC address */
 247         if (!ll->seed_set)
 248                 ll->seed.value = htole64(siphash24(ll->mac.ether_addr_octet, ETH_ALEN, MAC_HASH_KEY.bytes));
 249
 250         if (reset_generation)
 251                 ll->seed.generation = 0;
 252
 253         if (ll->address == 0) {
 254                 r = ipv4ll_pick_address(ll);
 255                 if (r < 0)
 256                         return r;
 257
 258                 picked_address = true;
 259         }
 260
 261         r = sd_ipv4acd_start(ll->acd, reset_generation);
 262         if (r < 0) {
 263
 264                 /* We couldn't start? If so, let's forget the picked address again, the user might make a change and
 265                  * retry, and we want the new data to take effect when picking an address. */
 266                 if (picked_address)
 267                         ll->address = 0;
 268
 269                 return r;
 270         }
 271
 272         return 1;
 273 }
 274
 275 int sd_ipv4ll_start(sd_ipv4ll *ll) {
 276         assert_return(ll, -EINVAL);
 277
 278         if (sd_ipv4ll_is_running(ll))
 279                 return 0;
 280
 281         return ipv4ll_start_internal(ll, true);
 282 }
 283
 284 int sd_ipv4ll_restart(sd_ipv4ll *ll) {
 285         ll->address = 0;
 286
 287         return ipv4ll_start_internal(ll, false);
 288 }
 289
 290 static void ipv4ll_client_notify(sd_ipv4ll *ll, int event) {
 291         assert(ll);
 292
 293         if (ll->callback)
 294                 ll->callback(ll, event, ll->userdata);
 295 }
 296
 297 void ipv4ll_on_acd(sd_ipv4acd *acd, int event, void *userdata) {
 298         sd_ipv4ll *ll = userdata;
 299         IPV4LL_DONT_DESTROY(ll);
 300         int r;
 301
 302         assert(acd);
 303         assert(ll);
 304
 305         switch (event) {
 306
 307         case SD_IPV4ACD_EVENT_STOP:
 308                 ipv4ll_client_notify(ll, SD_IPV4LL_EVENT_STOP);
 309                 ll->claimed_address = 0;
 310                 break;
 311
 312         case SD_IPV4ACD_EVENT_BIND:
 313                 ll->claimed_address = ll->address;
 314                 ipv4ll_client_notify(ll, SD_IPV4LL_EVENT_BIND);
 315                 break;
 316
 317         case SD_IPV4ACD_EVENT_CONFLICT:
 318                 /* if an address was already bound we must call up to the
 319                    user to handle this, otherwise we just try again */
 320                 if (ll->claimed_address != 0) {
 321                         ipv4ll_client_notify(ll, SD_IPV4LL_EVENT_CONFLICT);
 322
 323                         ll->claimed_address = 0;
 324                 } else {
 325                         r = sd_ipv4ll_restart(ll);
 326                         if (r < 0)
 327                                 goto error;
 328                 }
 329
 330                 break;
 331
 332         default:
 333                 assert_not_reached("Invalid IPv4ACD event.");
 334         }
 335
 336         return;
 337
 338 error:
 339         ipv4ll_client_notify(ll, SD_IPV4LL_EVENT_STOP);
 340 }