src/libsystemd-network/sd-ipv4ll.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   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 "list.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, ...) log_internal(LOG_DEBUG, error, PROJECT_FILE, __LINE__, __func__, "IPV4LL: " fmt, ##__VA_ARGS__)
  53 #define log_ipv4ll(ll, fmt, ...) log_ipv4ll_errno(ll, 0, fmt, ##__VA_ARGS__)
  54
  55 static void ipv4ll_on_acd(sd_ipv4acd *ll, int event, void *userdata);
  56
  57 static sd_ipv4ll *ipv4ll_free(sd_ipv4ll *ll) {
  58         assert(ll);
  59
  60         sd_ipv4acd_unref(ll->acd);
  61         return mfree(ll);
  62 }
  63
  64 DEFINE_TRIVIAL_REF_UNREF_FUNC(sd_ipv4ll, sd_ipv4ll, ipv4ll_free);
  65
  66 int sd_ipv4ll_new(sd_ipv4ll **ret) {
  67         _cleanup_(sd_ipv4ll_unrefp) sd_ipv4ll *ll = NULL;
  68         int r;
  69
  70         assert_return(ret, -EINVAL);
  71
  72         ll = new0(sd_ipv4ll, 1);
  73         if (!ll)
  74                 return -ENOMEM;
  75
  76         ll->n_ref = 1;
  77
  78         r = sd_ipv4acd_new(&ll->acd);
  79         if (r < 0)
  80                 return r;
  81
  82         r = sd_ipv4acd_set_callback(ll->acd, ipv4ll_on_acd, ll);
  83         if (r < 0)
  84                 return r;
  85
  86         *ret = TAKE_PTR(ll);
  87
  88         return 0;
  89 }
  90
  91 int sd_ipv4ll_stop(sd_ipv4ll *ll) {
  92         assert_return(ll, -EINVAL);
  93
  94         return sd_ipv4acd_stop(ll->acd);
  95 }
  96
  97 int sd_ipv4ll_set_ifindex(sd_ipv4ll *ll, int ifindex) {
  98         assert_return(ll, -EINVAL);
  99         assert_return(ifindex > 0, -EINVAL);
 100         assert_return(sd_ipv4ll_is_running(ll) == 0, -EBUSY);
 101
 102         return sd_ipv4acd_set_ifindex(ll->acd, ifindex);
 103 }
 104
 105 int sd_ipv4ll_set_mac(sd_ipv4ll *ll, const struct ether_addr *addr) {
 106         int r;
 107
 108         assert_return(ll, -EINVAL);
 109         assert_return(addr, -EINVAL);
 110         assert_return(sd_ipv4ll_is_running(ll) == 0, -EBUSY);
 111
 112         r = sd_ipv4acd_set_mac(ll->acd, addr);
 113         if (r < 0)
 114                 return r;
 115
 116         ll->mac = *addr;
 117         return 0;
 118 }
 119
 120 int sd_ipv4ll_detach_event(sd_ipv4ll *ll) {
 121         assert_return(ll, -EINVAL);
 122
 123         return sd_ipv4acd_detach_event(ll->acd);
 124 }
 125
 126 int sd_ipv4ll_attach_event(sd_ipv4ll *ll, sd_event *event, int64_t priority) {
 127         assert_return(ll, -EINVAL);
 128
 129         return sd_ipv4acd_attach_event(ll->acd, event, priority);
 130 }
 131
 132 int sd_ipv4ll_set_callback(sd_ipv4ll *ll, sd_ipv4ll_callback_t cb, void *userdata) {
 133         assert_return(ll, -EINVAL);
 134
 135         ll->callback = cb;
 136         ll->userdata = userdata;
 137
 138         return 0;
 139 }
 140
 141 int sd_ipv4ll_get_address(sd_ipv4ll *ll, struct in_addr *address) {
 142         assert_return(ll, -EINVAL);
 143         assert_return(address, -EINVAL);
 144
 145         if (ll->claimed_address == 0)
 146                 return -ENOENT;
 147
 148         address->s_addr = ll->claimed_address;
 149
 150         return 0;
 151 }
 152
 153 int sd_ipv4ll_set_address_seed(sd_ipv4ll *ll, uint64_t seed) {
 154         assert_return(ll, -EINVAL);
 155         assert_return(sd_ipv4ll_is_running(ll) == 0, -EBUSY);
 156
 157         ll->seed.value = htole64(seed);
 158         ll->seed_set = true;
 159
 160         return 0;
 161 }
 162
 163 int sd_ipv4ll_is_running(sd_ipv4ll *ll) {
 164         assert_return(ll, false);
 165
 166         return sd_ipv4acd_is_running(ll->acd);
 167 }
 168
 169 static bool ipv4ll_address_is_valid(const struct in_addr *address) {
 170         assert(address);
 171
 172         if (!in_addr_is_link_local(AF_INET, (const union in_addr_union *) address))
 173                 return false;
 174
 175         return !IN_SET(be32toh(address->s_addr) & 0x0000FF00U, 0x0000U, 0xFF00U);
 176 }
 177
 178 int sd_ipv4ll_set_address(sd_ipv4ll *ll, const struct in_addr *address) {
 179         int r;
 180
 181         assert_return(ll, -EINVAL);
 182         assert_return(address, -EINVAL);
 183         assert_return(ipv4ll_address_is_valid(address), -EINVAL);
 184
 185         r = sd_ipv4acd_set_address(ll->acd, address);
 186         if (r < 0)
 187                 return r;
 188
 189         ll->address = address->s_addr;
 190
 191         return 0;
 192 }
 193
 194 #define PICK_HASH_KEY SD_ID128_MAKE(15,ac,82,a6,d6,3f,49,78,98,77,5d,0c,69,02,94,0b)
 195
 196 static int ipv4ll_pick_address(sd_ipv4ll *ll) {
 197         _cleanup_free_ char *address = NULL;
 198         be32_t addr;
 199
 200         assert(ll);
 201
 202         do {
 203                 uint64_t h;
 204
 205                 h = siphash24(&ll->seed, sizeof(ll->seed), PICK_HASH_KEY.bytes);
 206
 207                 /* Increase the generation counter by one */
 208                 ll->seed.generation = htole64(le64toh(ll->seed.generation) + 1);
 209
 210                 addr = htobe32((h & UINT32_C(0x0000FFFF)) | IPV4LL_NETWORK);
 211         } while (addr == ll->address ||
 212                  IN_SET(be32toh(addr) & 0x0000FF00U, 0x0000U, 0xFF00U));
 213
 214         (void) in_addr_to_string(AF_INET, &(union in_addr_union) { .in.s_addr = addr }, &address);
 215         log_ipv4ll(ll, "Picked new IP address %s.", strna(address));
 216
 217         return sd_ipv4ll_set_address(ll, &(struct in_addr) { addr });
 218 }
 219
 220 #define MAC_HASH_KEY SD_ID128_MAKE(df,04,22,98,3f,ad,14,52,f9,87,2e,d1,9c,70,e2,f2)
 221
 222 static int ipv4ll_start_internal(sd_ipv4ll *ll, bool reset_generation) {
 223         int r;
 224         bool picked_address = false;
 225
 226         assert_return(ll, -EINVAL);
 227         assert_return(!ether_addr_is_null(&ll->mac), -EINVAL);
 228
 229         /* If no random seed is set, generate some from the MAC address */
 230         if (!ll->seed_set)
 231                 ll->seed.value = htole64(siphash24(ll->mac.ether_addr_octet, ETH_ALEN, MAC_HASH_KEY.bytes));
 232
 233         if (reset_generation)
 234                 ll->seed.generation = 0;
 235
 236         if (ll->address == 0) {
 237                 r = ipv4ll_pick_address(ll);
 238                 if (r < 0)
 239                         return r;
 240
 241                 picked_address = true;
 242         }
 243
 244         r = sd_ipv4acd_start(ll->acd, reset_generation);
 245         if (r < 0) {
 246
 247                 /* We couldn't start? If so, let's forget the picked address again, the user might make a change and
 248                  * retry, and we want the new data to take effect when picking an address. */
 249                 if (picked_address)
 250                         ll->address = 0;
 251
 252                 return r;
 253         }
 254
 255         return 0;
 256 }
 257
 258 int sd_ipv4ll_start(sd_ipv4ll *ll) {
 259         assert_return(ll, -EINVAL);
 260         assert_return(sd_ipv4ll_is_running(ll) == 0, -EBUSY);
 261
 262         return ipv4ll_start_internal(ll, true);
 263 }
 264
 265 int sd_ipv4ll_restart(sd_ipv4ll *ll) {
 266         ll->address = 0;
 267
 268         return ipv4ll_start_internal(ll, false);
 269 }
 270
 271 static void ipv4ll_client_notify(sd_ipv4ll *ll, int event) {
 272         assert(ll);
 273
 274         if (ll->callback)
 275                 ll->callback(ll, event, ll->userdata);
 276 }
 277
 278 void ipv4ll_on_acd(sd_ipv4acd *acd, int event, void *userdata) {
 279         sd_ipv4ll *ll = userdata;
 280         IPV4LL_DONT_DESTROY(ll);
 281         int r;
 282
 283         assert(acd);
 284         assert(ll);
 285
 286         switch (event) {
 287
 288         case SD_IPV4ACD_EVENT_STOP:
 289                 ipv4ll_client_notify(ll, SD_IPV4LL_EVENT_STOP);
 290                 ll->claimed_address = 0;
 291                 break;
 292
 293         case SD_IPV4ACD_EVENT_BIND:
 294                 ll->claimed_address = ll->address;
 295                 ipv4ll_client_notify(ll, SD_IPV4LL_EVENT_BIND);
 296                 break;
 297
 298         case SD_IPV4ACD_EVENT_CONFLICT:
 299                 /* if an address was already bound we must call up to the
 300                    user to handle this, otherwise we just try again */
 301                 if (ll->claimed_address != 0) {
 302                         ipv4ll_client_notify(ll, SD_IPV4LL_EVENT_CONFLICT);
 303
 304                         ll->claimed_address = 0;
 305                 } else {
 306                         r = sd_ipv4ll_restart(ll);
 307                         if (r < 0)
 308                                 goto error;
 309                 }
 310
 311                 break;
 312
 313         default:
 314                 assert_not_reached("Invalid IPv4ACD event.");
 315         }
 316
 317         return;
 318
 319 error:
 320         ipv4ll_client_notify(ll, SD_IPV4LL_EVENT_STOP);
 321 }