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