src/libsystemd-network/sd-ipv4ll.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2 /***
   3   Copyright (C) 2014 Axis Communications AB. All rights reserved.
   4   Copyright (C) 2015 Tom Gundersen
   5 ***/
   6
   7 #include <arpa/inet.h>
   8 #include <errno.h>
   9 #include <stdio.h>
  10 #include <stdlib.h>
  11 #include <string.h>
  12
  13 #include "sd-id128.h"
  14 #include "sd-ipv4acd.h"
  15 #include "sd-ipv4ll.h"
  16
  17 #include "alloc-util.h"
  18 #include "ether-addr-util.h"
  19 #include "in-addr-util.h"
  20 #include "list.h"
  21 #include "random-util.h"
  22 #include "siphash24.h"
  23 #include "sparse-endian.h"
  24 #include "string-util.h"
  25 #include "util.h"
  26
  27 #define IPV4LL_NETWORK UINT32_C(0xA9FE0000)
  28 #define IPV4LL_NETMASK UINT32_C(0xFFFF0000)
  29
  30 #define IPV4LL_DONT_DESTROY(ll) \
  31         _cleanup_(sd_ipv4ll_unrefp) _unused_ sd_ipv4ll *_dont_destroy_##ll = sd_ipv4ll_ref(ll)
  32
  33 struct sd_ipv4ll {
  34         unsigned n_ref;
  35
  36         sd_ipv4acd *acd;
  37
  38         be32_t address; /* the address pushed to ACD */
  39         struct ether_addr mac;
  40
  41         struct {
  42                 le64_t value;
  43                 le64_t generation;
  44         } seed;
  45         bool seed_set;
  46
  47         /* External */
  48         be32_t claimed_address;
  49
  50         sd_ipv4ll_callback_t callback;
  51         void* userdata;
  52 };
  53
  54 #define log_ipv4ll_errno(ll, error, fmt, ...) log_internal(LOG_DEBUG, error, __FILE__, __LINE__, __func__, "IPV4LL: " fmt, ##__VA_ARGS__)
  55 #define log_ipv4ll(ll, fmt, ...) log_ipv4ll_errno(ll, 0, fmt, ##__VA_ARGS__)
  56
  57 static void ipv4ll_on_acd(sd_ipv4acd *ll, int event, void *userdata);
  58
  59 sd_ipv4ll *sd_ipv4ll_ref(sd_ipv4ll *ll) {
  60         if (!ll)
  61                 return NULL;
  62
  63         assert(ll->n_ref >= 1);
  64         ll->n_ref++;
  65
  66         return ll;
  67 }
  68
  69 sd_ipv4ll *sd_ipv4ll_unref(sd_ipv4ll *ll) {
  70         if (!ll)
  71                 return NULL;
  72
  73         assert(ll->n_ref >= 1);
  74         ll->n_ref--;
  75
  76         if (ll->n_ref > 0)
  77                 return NULL;
  78
  79         sd_ipv4acd_unref(ll->acd);
  80         return mfree(ll);
  81 }
  82
  83 int sd_ipv4ll_new(sd_ipv4ll **ret) {
  84         _cleanup_(sd_ipv4ll_unrefp) sd_ipv4ll *ll = NULL;
  85         int r;
  86
  87         assert_return(ret, -EINVAL);
  88
  89         ll = new0(sd_ipv4ll, 1);
  90         if (!ll)
  91                 return -ENOMEM;
  92
  93         ll->n_ref = 1;
  94
  95         r = sd_ipv4acd_new(&ll->acd);
  96         if (r < 0)
  97                 return r;
  98
  99         r = sd_ipv4acd_set_callback(ll->acd, ipv4ll_on_acd, ll);
 100         if (r < 0)
 101                 return r;
 102
 103         *ret = TAKE_PTR(ll);
 104
 105         return 0;
 106 }
 107
 108 int sd_ipv4ll_stop(sd_ipv4ll *ll) {
 109         assert_return(ll, -EINVAL);
 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_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 (!in_addr_is_link_local(AF_INET, (const union in_addr_union *) 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 int sd_ipv4ll_restart(sd_ipv4ll *ll) {
 238         ll->address = 0;
 239
 240         return sd_ipv4ll_start(ll);
 241 }
 242
 243 #define MAC_HASH_KEY SD_ID128_MAKE(df,04,22,98,3f,ad,14,52,f9,87,2e,d1,9c,70,e2,f2)
 244
 245 int sd_ipv4ll_start(sd_ipv4ll *ll) {
 246         int r;
 247         bool picked_address = false;
 248
 249         assert_return(ll, -EINVAL);
 250         assert_return(!ether_addr_is_null(&ll->mac), -EINVAL);
 251         assert_return(sd_ipv4ll_is_running(ll) == 0, -EBUSY);
 252
 253         /* If no random seed is set, generate some from the MAC address */
 254         if (!ll->seed_set)
 255                 ll->seed.value = htole64(siphash24(ll->mac.ether_addr_octet, ETH_ALEN, MAC_HASH_KEY.bytes));
 256
 257         /* Restart the generation counter. */
 258         ll->seed.generation = 0;
 259
 260         if (ll->address == 0) {
 261                 r = ipv4ll_pick_address(ll);
 262                 if (r < 0)
 263                         return r;
 264
 265                 picked_address = true;
 266         }
 267
 268         r = sd_ipv4acd_start(ll->acd);
 269         if (r < 0) {
 270
 271                 /* We couldn't start? If so, let's forget the picked address again, the user might make a change and
 272                  * retry, and we want the new data to take effect when picking an address. */
 273                 if (picked_address)
 274                         ll->address = 0;
 275
 276                 return r;
 277         }
 278
 279         return 0;
 280 }
 281
 282 static void ipv4ll_client_notify(sd_ipv4ll *ll, int event) {
 283         assert(ll);
 284
 285         if (ll->callback)
 286                 ll->callback(ll, event, ll->userdata);
 287 }
 288
 289 void ipv4ll_on_acd(sd_ipv4acd *acd, int event, void *userdata) {
 290         sd_ipv4ll *ll = userdata;
 291         IPV4LL_DONT_DESTROY(ll);
 292         int r;
 293
 294         assert(acd);
 295         assert(ll);
 296
 297         switch (event) {
 298
 299         case SD_IPV4ACD_EVENT_STOP:
 300                 ipv4ll_client_notify(ll, SD_IPV4LL_EVENT_STOP);
 301                 ll->claimed_address = 0;
 302                 break;
 303
 304         case SD_IPV4ACD_EVENT_BIND:
 305                 ll->claimed_address = ll->address;
 306                 ipv4ll_client_notify(ll, SD_IPV4LL_EVENT_BIND);
 307                 break;
 308
 309         case SD_IPV4ACD_EVENT_CONFLICT:
 310                 /* if an address was already bound we must call up to the
 311                    user to handle this, otherwise we just try again */
 312                 if (ll->claimed_address != 0) {
 313                         ipv4ll_client_notify(ll, SD_IPV4LL_EVENT_CONFLICT);
 314
 315                         ll->claimed_address = 0;
 316                 } else {
 317                         r = ipv4ll_pick_address(ll);
 318                         if (r < 0)
 319                                 goto error;
 320
 321                         r = sd_ipv4acd_start(ll->acd);
 322                         if (r < 0)
 323                                 goto error;
 324                 }
 325
 326                 break;
 327
 328         default:
 329                 assert_not_reached("Invalid IPv4ACD event.");
 330         }
 331
 332         return;
 333
 334 error:
 335         ipv4ll_client_notify(ll, SD_IPV4LL_EVENT_STOP);
 336 }