src/libsystemd-network/sd-ndisc.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2 /***
   3   Copyright © 2014 Intel Corporation. All rights reserved.
   4 ***/
   5
   6 #include <netinet/icmp6.h>
   7 #include <netinet/in.h>
   8
   9 #include "sd-ndisc.h"
  10
  11 #include "alloc-util.h"
  12 #include "fd-util.h"
  13 #include "icmp6-util.h"
  14 #include "in-addr-util.h"
  15 #include "ndisc-internal.h"
  16 #include "ndisc-router.h"
  17 #include "random-util.h"
  18 #include "socket-util.h"
  19 #include "string-util.h"
  20 #include "util.h"
  21
  22 #define NDISC_TIMEOUT_NO_RA_USEC (NDISC_ROUTER_SOLICITATION_INTERVAL * NDISC_MAX_ROUTER_SOLICITATIONS)
  23
  24 static void ndisc_callback(sd_ndisc *ndisc, sd_ndisc_event event, sd_ndisc_router *rt) {
  25         assert(ndisc);
  26
  27         log_ndisc("Invoking callback for '%c'.", event);
  28
  29         if (!ndisc->callback)
  30                 return;
  31
  32         ndisc->callback(ndisc, event, rt, ndisc->userdata);
  33 }
  34
  35 _public_ int sd_ndisc_set_callback(
  36                 sd_ndisc *nd,
  37                 sd_ndisc_callback_t callback,
  38                 void *userdata) {
  39
  40         assert_return(nd, -EINVAL);
  41
  42         nd->callback = callback;
  43         nd->userdata = userdata;
  44
  45         return 0;
  46 }
  47
  48 _public_ int sd_ndisc_set_ifindex(sd_ndisc *nd, int ifindex) {
  49         assert_return(nd, -EINVAL);
  50         assert_return(ifindex > 0, -EINVAL);
  51         assert_return(nd->fd < 0, -EBUSY);
  52
  53         nd->ifindex = ifindex;
  54         return 0;
  55 }
  56
  57 _public_ int sd_ndisc_set_mac(sd_ndisc *nd, const struct ether_addr *mac_addr) {
  58         assert_return(nd, -EINVAL);
  59
  60         if (mac_addr)
  61                 nd->mac_addr = *mac_addr;
  62         else
  63                 zero(nd->mac_addr);
  64
  65         return 0;
  66 }
  67
  68 _public_ int sd_ndisc_attach_event(sd_ndisc *nd, sd_event *event, int64_t priority) {
  69         int r;
  70
  71         assert_return(nd, -EINVAL);
  72         assert_return(nd->fd < 0, -EBUSY);
  73         assert_return(!nd->event, -EBUSY);
  74
  75         if (event)
  76                 nd->event = sd_event_ref(event);
  77         else {
  78                 r = sd_event_default(&nd->event);
  79                 if (r < 0)
  80                         return 0;
  81         }
  82
  83         nd->event_priority = priority;
  84
  85         return 0;
  86 }
  87
  88 _public_ int sd_ndisc_detach_event(sd_ndisc *nd) {
  89
  90         assert_return(nd, -EINVAL);
  91         assert_return(nd->fd < 0, -EBUSY);
  92
  93         nd->event = sd_event_unref(nd->event);
  94         return 0;
  95 }
  96
  97 _public_ sd_event *sd_ndisc_get_event(sd_ndisc *nd) {
  98         assert_return(nd, NULL);
  99
 100         return nd->event;
 101 }
 102
 103 static int ndisc_reset(sd_ndisc *nd) {
 104         assert(nd);
 105
 106         nd->timeout_event_source = sd_event_source_unref(nd->timeout_event_source);
 107         nd->timeout_no_ra = sd_event_source_unref(nd->timeout_no_ra);
 108         nd->retransmit_time = 0;
 109         nd->recv_event_source = sd_event_source_unref(nd->recv_event_source);
 110         nd->fd = safe_close(nd->fd);
 111
 112         return 0;
 113 }
 114
 115 static sd_ndisc *ndisc_free(sd_ndisc *nd) {
 116         assert(nd);
 117
 118         ndisc_reset(nd);
 119         sd_ndisc_detach_event(nd);
 120         return mfree(nd);
 121 }
 122
 123 DEFINE_PUBLIC_TRIVIAL_REF_UNREF_FUNC(sd_ndisc, sd_ndisc, ndisc_free);
 124
 125 _public_ int sd_ndisc_new(sd_ndisc **ret) {
 126         _cleanup_(sd_ndisc_unrefp) sd_ndisc *nd = NULL;
 127
 128         assert_return(ret, -EINVAL);
 129
 130         nd = new0(sd_ndisc, 1);
 131         if (!nd)
 132                 return -ENOMEM;
 133
 134         nd->n_ref = 1;
 135         nd->fd = -1;
 136
 137         *ret = TAKE_PTR(nd);
 138
 139         return 0;
 140 }
 141
 142 _public_ int sd_ndisc_get_mtu(sd_ndisc *nd, uint32_t *mtu) {
 143         assert_return(nd, -EINVAL);
 144         assert_return(mtu, -EINVAL);
 145
 146         if (nd->mtu == 0)
 147                 return -ENODATA;
 148
 149         *mtu = nd->mtu;
 150         return 0;
 151 }
 152
 153 _public_ int sd_ndisc_get_hop_limit(sd_ndisc *nd, uint8_t *ret) {
 154         assert_return(nd, -EINVAL);
 155         assert_return(ret, -EINVAL);
 156
 157         if (nd->hop_limit == 0)
 158                 return -ENODATA;
 159
 160         *ret = nd->hop_limit;
 161         return 0;
 162 }
 163
 164 static int ndisc_handle_datagram(sd_ndisc *nd, sd_ndisc_router *rt) {
 165         int r;
 166
 167         assert(nd);
 168         assert(rt);
 169
 170         r = ndisc_router_parse(rt);
 171         if (r == -EBADMSG) /* Bad packet */
 172                 return 0;
 173         if (r < 0)
 174                 return 0;
 175
 176         /* Update global variables we keep */
 177         if (rt->mtu > 0)
 178                 nd->mtu = rt->mtu;
 179         if (rt->hop_limit > 0)
 180                 nd->hop_limit = rt->hop_limit;
 181
 182         log_ndisc("Received Router Advertisement: flags %s preference %s lifetime %" PRIu16 " sec",
 183                   rt->flags & ND_RA_FLAG_MANAGED ? "MANAGED" : rt->flags & ND_RA_FLAG_OTHER ? "OTHER" : "none",
 184                   rt->preference == SD_NDISC_PREFERENCE_HIGH ? "high" : rt->preference == SD_NDISC_PREFERENCE_LOW ? "low" : "medium",
 185                   rt->lifetime);
 186
 187         ndisc_callback(nd, SD_NDISC_EVENT_ROUTER, rt);
 188         return 0;
 189 }
 190
 191 static int ndisc_recv(sd_event_source *s, int fd, uint32_t revents, void *userdata) {
 192         _cleanup_(sd_ndisc_router_unrefp) sd_ndisc_router *rt = NULL;
 193         sd_ndisc *nd = userdata;
 194         ssize_t buflen;
 195         int r;
 196         _cleanup_free_ char *addr = NULL;
 197
 198         assert(s);
 199         assert(nd);
 200         assert(nd->event);
 201
 202         buflen = next_datagram_size_fd(fd);
 203         if (buflen < 0)
 204                 return log_ndisc_errno(buflen, "Failed to determine datagram size to read: %m");
 205
 206         rt = ndisc_router_new(buflen);
 207         if (!rt)
 208                 return -ENOMEM;
 209
 210         r = icmp6_receive(fd, NDISC_ROUTER_RAW(rt), rt->raw_size, &rt->address,
 211                      &rt->timestamp);
 212         if (r < 0) {
 213                 switch (r) {
 214                 case -EADDRNOTAVAIL:
 215                         (void) in_addr_to_string(AF_INET6, (union in_addr_union*) &rt->address, &addr);
 216                         log_ndisc("Received RA from non-link-local address %s. Ignoring", addr);
 217                         break;
 218
 219                 case -EMULTIHOP:
 220                         log_ndisc("Received RA with invalid hop limit. Ignoring.");
 221                         break;
 222
 223                 case -EPFNOSUPPORT:
 224                         log_ndisc("Received invalid source address from ICMPv6 socket. Ignoring.");
 225                         break;
 226
 227                 case -EAGAIN: /* ignore spurious wakeups */
 228                         break;
 229
 230                 default:
 231                         log_ndisc_errno(r, "Unexpected error while reading from ICMPv6, ignoring: %m");
 232                         break;
 233                 }
 234
 235                 return 0;
 236         }
 237
 238         nd->timeout_event_source = sd_event_source_unref(nd->timeout_event_source);
 239
 240         return ndisc_handle_datagram(nd, rt);
 241 }
 242
 243 static usec_t ndisc_timeout_compute_random(usec_t val) {
 244         /* compute a time that is random within ±10% of the given value */
 245         return val - val / 10 +
 246                 (random_u64() % (2 * USEC_PER_SEC)) * val / 10 / USEC_PER_SEC;
 247 }
 248
 249 static int ndisc_timeout(sd_event_source *s, uint64_t usec, void *userdata) {
 250         sd_ndisc *nd = userdata;
 251         usec_t time_now;
 252         int r;
 253         char time_string[FORMAT_TIMESPAN_MAX];
 254
 255         assert(s);
 256         assert(nd);
 257         assert(nd->event);
 258
 259         assert_se(sd_event_now(nd->event, clock_boottime_or_monotonic(), &time_now) >= 0);
 260
 261         nd->timeout_event_source = sd_event_source_unref(nd->timeout_event_source);
 262
 263         if (!nd->retransmit_time)
 264                 nd->retransmit_time = ndisc_timeout_compute_random(NDISC_ROUTER_SOLICITATION_INTERVAL);
 265         else {
 266                 if (nd->retransmit_time > NDISC_MAX_ROUTER_SOLICITATION_INTERVAL / 2)
 267                         nd->retransmit_time = ndisc_timeout_compute_random(NDISC_MAX_ROUTER_SOLICITATION_INTERVAL);
 268                 else
 269                         nd->retransmit_time += ndisc_timeout_compute_random(nd->retransmit_time);
 270         }
 271
 272         r = sd_event_add_time(nd->event, &nd->timeout_event_source,
 273                               clock_boottime_or_monotonic(),
 274                               time_now + nd->retransmit_time,
 275                               10 * USEC_PER_MSEC, ndisc_timeout, nd);
 276         if (r < 0)
 277                 goto fail;
 278
 279         r = sd_event_source_set_priority(nd->timeout_event_source, nd->event_priority);
 280         if (r < 0)
 281                 goto fail;
 282
 283         (void) sd_event_source_set_description(nd->timeout_event_source, "ndisc-timeout-no-ra");
 284
 285         r = sd_event_source_set_enabled(nd->timeout_event_source, SD_EVENT_ONESHOT);
 286         if (r < 0) {
 287                 log_ndisc_errno(r, "Error reenabling timer: %m");
 288                 goto fail;
 289         }
 290
 291         r = icmp6_send_router_solicitation(nd->fd, &nd->mac_addr);
 292         if (r < 0) {
 293                 log_ndisc_errno(r, "Error sending Router Solicitation: %m");
 294                 goto fail;
 295         }
 296
 297         log_ndisc("Sent Router Solicitation, next solicitation in %s",
 298                   format_timespan(time_string, FORMAT_TIMESPAN_MAX,
 299                                   nd->retransmit_time, USEC_PER_SEC));
 300
 301         return 0;
 302
 303 fail:
 304         sd_ndisc_stop(nd);
 305         return 0;
 306 }
 307
 308 static int ndisc_timeout_no_ra(sd_event_source *s, uint64_t usec, void *userdata) {
 309         sd_ndisc *nd = userdata;
 310
 311         assert(s);
 312         assert(nd);
 313
 314         log_ndisc("No RA received before link confirmation timeout");
 315
 316         nd->timeout_no_ra = sd_event_source_unref(nd->timeout_no_ra);
 317         ndisc_callback(nd, SD_NDISC_EVENT_TIMEOUT, NULL);
 318
 319         return 0;
 320 }
 321
 322 _public_ int sd_ndisc_stop(sd_ndisc *nd) {
 323         assert_return(nd, -EINVAL);
 324
 325         if (nd->fd < 0)
 326                 return 0;
 327
 328         log_ndisc("Stopping IPv6 Router Solicitation client");
 329
 330         ndisc_reset(nd);
 331         return 1;
 332 }
 333
 334 _public_ int sd_ndisc_start(sd_ndisc *nd) {
 335         int r;
 336         usec_t time_now;
 337
 338         assert_return(nd, -EINVAL);
 339         assert_return(nd->event, -EINVAL);
 340         assert_return(nd->ifindex > 0, -EINVAL);
 341
 342         if (nd->fd >= 0)
 343                 return 0;
 344
 345         assert(!nd->recv_event_source);
 346         assert(!nd->timeout_event_source);
 347
 348         r = sd_event_now(nd->event, clock_boottime_or_monotonic(), &time_now);
 349         if (r < 0)
 350                 goto fail;
 351
 352         nd->fd = icmp6_bind_router_solicitation(nd->ifindex);
 353         if (nd->fd < 0)
 354                 return nd->fd;
 355
 356         r = sd_event_add_io(nd->event, &nd->recv_event_source, nd->fd, EPOLLIN, ndisc_recv, nd);
 357         if (r < 0)
 358                 goto fail;
 359
 360         r = sd_event_source_set_priority(nd->recv_event_source, nd->event_priority);
 361         if (r < 0)
 362                 goto fail;
 363
 364         (void) sd_event_source_set_description(nd->recv_event_source, "ndisc-receive-message");
 365
 366         r = sd_event_add_time(nd->event, &nd->timeout_event_source, clock_boottime_or_monotonic(), 0, 0, ndisc_timeout, nd);
 367         if (r < 0)
 368                 goto fail;
 369
 370         r = sd_event_source_set_priority(nd->timeout_event_source, nd->event_priority);
 371         if (r < 0)
 372                 goto fail;
 373
 374         (void) sd_event_source_set_description(nd->timeout_event_source, "ndisc-timeout");
 375
 376         r = sd_event_add_time(nd->event, &nd->timeout_no_ra,
 377                               clock_boottime_or_monotonic(),
 378                               time_now + NDISC_TIMEOUT_NO_RA_USEC,
 379                               10 * USEC_PER_MSEC, ndisc_timeout_no_ra, nd);
 380         if (r < 0)
 381                 goto fail;
 382
 383         r = sd_event_source_set_priority(nd->timeout_no_ra, nd->event_priority);
 384         if (r < 0)
 385                 goto fail;
 386
 387         (void) sd_event_source_set_description(nd->timeout_no_ra, "ndisc-timeout-no-ra");
 388
 389         log_ndisc("Started IPv6 Router Solicitation client");
 390         return 1;
 391
 392 fail:
 393         ndisc_reset(nd);
 394         return r;
 395 }