Samuel Tan | d7ed851 | 2015-08-13 16:11:35 -0700 | [diff] [blame^] | 1 | /* |
| 2 | * dhcpcd - DHCP client daemon |
| 3 | * Copyright (c) 2006-2015 Roy Marples <roy@marples.name> |
| 4 | * All rights reserved |
| 5 | |
| 6 | * Redistribution and use in source and binary forms, with or without |
| 7 | * modification, are permitted provided that the following conditions |
| 8 | * are met: |
| 9 | * 1. Redistributions of source code must retain the above copyright |
| 10 | * notice, this list of conditions and the following disclaimer. |
| 11 | * 2. Redistributions in binary form must reproduce the above copyright |
| 12 | * notice, this list of conditions and the following disclaimer in the |
| 13 | * documentation and/or other materials provided with the distribution. |
| 14 | * |
| 15 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND |
| 16 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| 17 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| 18 | * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE |
| 19 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
| 20 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
| 21 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
| 22 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
| 23 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
| 24 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| 25 | * SUCH DAMAGE. |
| 26 | */ |
| 27 | |
| 28 | #include <sys/socket.h> |
| 29 | #include <sys/types.h> |
| 30 | |
| 31 | #include <net/if.h> |
| 32 | #include <netinet/in.h> |
| 33 | #include <netinet/if_ether.h> |
| 34 | |
| 35 | #include <errno.h> |
| 36 | #include <signal.h> |
| 37 | #include <stdlib.h> |
| 38 | #include <string.h> |
| 39 | #include <unistd.h> |
| 40 | |
| 41 | #define ELOOP_QUEUE 5 |
| 42 | #include "config.h" |
| 43 | #include "arp.h" |
| 44 | #include "if.h" |
| 45 | #include "ipv4.h" |
| 46 | #include "common.h" |
| 47 | #include "dhcp.h" |
| 48 | #include "dhcpcd.h" |
| 49 | #include "eloop.h" |
| 50 | #include "if.h" |
| 51 | #include "if-options.h" |
| 52 | #include "ipv4ll.h" |
| 53 | |
| 54 | #define ARP_LEN \ |
| 55 | (sizeof(struct arphdr) + (2 * sizeof(uint32_t)) + (2 * HWADDR_LEN)) |
| 56 | |
| 57 | static ssize_t |
| 58 | arp_request(const struct interface *ifp, in_addr_t sip, in_addr_t tip) |
| 59 | { |
| 60 | uint8_t arp_buffer[ARP_LEN]; |
| 61 | struct arphdr ar; |
| 62 | size_t len; |
| 63 | uint8_t *p; |
| 64 | |
| 65 | ar.ar_hrd = htons(ifp->family); |
| 66 | ar.ar_pro = htons(ETHERTYPE_IP); |
| 67 | ar.ar_hln = ifp->hwlen; |
| 68 | ar.ar_pln = sizeof(sip); |
| 69 | ar.ar_op = htons(ARPOP_REQUEST); |
| 70 | |
| 71 | p = arp_buffer; |
| 72 | len = 0; |
| 73 | |
| 74 | #define CHECK(fun, b, l) \ |
| 75 | do { \ |
| 76 | if (len + (l) > sizeof(arp_buffer)) \ |
| 77 | goto eexit; \ |
| 78 | fun(p, (b), (l)); \ |
| 79 | p += (l); \ |
| 80 | len += (l); \ |
| 81 | } while (/* CONSTCOND */ 0) |
| 82 | #define APPEND(b, l) CHECK(memcpy, b, l) |
| 83 | #define ZERO(l) CHECK(memset, 0, l) |
| 84 | |
| 85 | APPEND(&ar, sizeof(ar)); |
| 86 | APPEND(ifp->hwaddr, ifp->hwlen); |
| 87 | APPEND(&sip, sizeof(sip)); |
| 88 | ZERO(ifp->hwlen); |
| 89 | APPEND(&tip, sizeof(tip)); |
| 90 | return if_sendrawpacket(ifp, ETHERTYPE_ARP, arp_buffer, len); |
| 91 | |
| 92 | eexit: |
| 93 | errno = ENOBUFS; |
| 94 | return -1; |
| 95 | } |
| 96 | |
| 97 | void |
| 98 | arp_report_conflicted(const struct arp_state *astate, const struct arp_msg *amsg) |
| 99 | { |
| 100 | |
| 101 | if (amsg) { |
| 102 | char buf[HWADDR_LEN * 3]; |
| 103 | |
| 104 | logger(astate->iface->ctx, LOG_ERR, |
| 105 | "%s: hardware address %s claims %s", |
| 106 | astate->iface->name, |
| 107 | hwaddr_ntoa(amsg->sha, astate->iface->hwlen, |
| 108 | buf, sizeof(buf)), |
| 109 | inet_ntoa(astate->failed)); |
| 110 | } else |
| 111 | logger(astate->iface->ctx, LOG_ERR, |
| 112 | "%s: DAD detected %s", |
| 113 | astate->iface->name, inet_ntoa(astate->failed)); |
| 114 | } |
| 115 | |
| 116 | static void |
| 117 | arp_packet(void *arg) |
| 118 | { |
| 119 | struct interface *ifp = arg; |
| 120 | const struct interface *ifn; |
| 121 | uint8_t arp_buffer[ARP_LEN]; |
| 122 | struct arphdr ar; |
| 123 | struct arp_msg arm; |
| 124 | ssize_t bytes; |
| 125 | struct dhcp_state *state; |
| 126 | struct arp_state *astate, *astaten; |
| 127 | unsigned char *hw_s, *hw_t; |
| 128 | int flags; |
| 129 | |
| 130 | state = D_STATE(ifp); |
| 131 | flags = 0; |
| 132 | while (!(flags & RAW_EOF)) { |
| 133 | bytes = if_readrawpacket(ifp, ETHERTYPE_ARP, |
| 134 | arp_buffer, sizeof(arp_buffer), &flags); |
| 135 | if (bytes == -1) { |
| 136 | logger(ifp->ctx, LOG_ERR, |
| 137 | "%s: arp if_readrawpacket: %m", ifp->name); |
| 138 | dhcp_close(ifp); |
| 139 | return; |
| 140 | } |
| 141 | /* We must have a full ARP header */ |
| 142 | if ((size_t)bytes < sizeof(ar)) |
| 143 | continue; |
| 144 | memcpy(&ar, arp_buffer, sizeof(ar)); |
| 145 | /* Families must match */ |
| 146 | if (ar.ar_hrd != htons(ifp->family)) |
| 147 | continue; |
| 148 | /* Protocol must be IP. */ |
| 149 | if (ar.ar_pro != htons(ETHERTYPE_IP)) |
| 150 | continue; |
| 151 | if (ar.ar_pln != sizeof(arm.sip.s_addr)) |
| 152 | continue; |
| 153 | /* Only these types are recognised */ |
| 154 | if (ar.ar_op != htons(ARPOP_REPLY) && |
| 155 | ar.ar_op != htons(ARPOP_REQUEST)) |
| 156 | continue; |
| 157 | |
| 158 | /* Get pointers to the hardware addreses */ |
| 159 | hw_s = arp_buffer + sizeof(ar); |
| 160 | hw_t = hw_s + ar.ar_hln + ar.ar_pln; |
| 161 | /* Ensure we got all the data */ |
| 162 | if ((hw_t + ar.ar_hln + ar.ar_pln) - arp_buffer > bytes) |
| 163 | continue; |
| 164 | /* Ignore messages from ourself */ |
| 165 | TAILQ_FOREACH(ifn, ifp->ctx->ifaces, next) { |
| 166 | if (ar.ar_hln == ifn->hwlen && |
| 167 | memcmp(hw_s, ifn->hwaddr, ifn->hwlen) == 0) |
| 168 | break; |
| 169 | } |
| 170 | if (ifn) |
| 171 | continue; |
| 172 | /* Copy out the HW and IP addresses */ |
| 173 | memcpy(&arm.sha, hw_s, ar.ar_hln); |
| 174 | memcpy(&arm.sip.s_addr, hw_s + ar.ar_hln, ar.ar_pln); |
| 175 | memcpy(&arm.tha, hw_t, ar.ar_hln); |
| 176 | memcpy(&arm.tip.s_addr, hw_t + ar.ar_hln, ar.ar_pln); |
| 177 | |
| 178 | /* Run the conflicts */ |
| 179 | TAILQ_FOREACH_SAFE(astate, &state->arp_states, next, astaten) { |
| 180 | if (astate->conflicted_cb) |
| 181 | astate->conflicted_cb(astate, &arm); |
| 182 | } |
| 183 | } |
| 184 | } |
| 185 | |
| 186 | static void |
| 187 | arp_open(struct interface *ifp) |
| 188 | { |
| 189 | struct dhcp_state *state; |
| 190 | |
| 191 | state = D_STATE(ifp); |
| 192 | if (state->arp_fd == -1) { |
| 193 | state->arp_fd = if_openrawsocket(ifp, ETHERTYPE_ARP); |
| 194 | if (state->arp_fd == -1) { |
| 195 | logger(ifp->ctx, LOG_ERR, "%s: %s: %m", |
| 196 | __func__, ifp->name); |
| 197 | return; |
| 198 | } |
| 199 | eloop_event_add(ifp->ctx->eloop, state->arp_fd, |
| 200 | arp_packet, ifp, NULL, NULL); |
| 201 | } |
| 202 | } |
| 203 | |
| 204 | static void |
| 205 | arp_announced(void *arg) |
| 206 | { |
| 207 | struct arp_state *astate = arg; |
| 208 | |
| 209 | if (astate->announced_cb) { |
| 210 | astate->announced_cb(astate); |
| 211 | return; |
| 212 | } |
| 213 | |
| 214 | /* Nothing more to do, so free us */ |
| 215 | arp_free(astate); |
| 216 | } |
| 217 | |
| 218 | static void |
| 219 | arp_announce1(void *arg) |
| 220 | { |
| 221 | struct arp_state *astate = arg; |
| 222 | struct interface *ifp = astate->iface; |
| 223 | |
| 224 | if (++astate->claims < ANNOUNCE_NUM) |
| 225 | logger(ifp->ctx, LOG_DEBUG, |
| 226 | "%s: ARP announcing %s (%d of %d), " |
| 227 | "next in %d.0 seconds", |
| 228 | ifp->name, inet_ntoa(astate->addr), |
| 229 | astate->claims, ANNOUNCE_NUM, ANNOUNCE_WAIT); |
| 230 | else |
| 231 | logger(ifp->ctx, LOG_DEBUG, |
| 232 | "%s: ARP announcing %s (%d of %d)", |
| 233 | ifp->name, inet_ntoa(astate->addr), |
| 234 | astate->claims, ANNOUNCE_NUM); |
| 235 | if (arp_request(ifp, astate->addr.s_addr, astate->addr.s_addr) == -1) |
| 236 | logger(ifp->ctx, LOG_ERR, "send_arp: %m"); |
| 237 | eloop_timeout_add_sec(ifp->ctx->eloop, ANNOUNCE_WAIT, |
| 238 | astate->claims < ANNOUNCE_NUM ? arp_announce1 : arp_announced, |
| 239 | astate); |
| 240 | } |
| 241 | |
| 242 | void |
| 243 | arp_announce(struct arp_state *astate) |
| 244 | { |
| 245 | |
| 246 | arp_open(astate->iface); |
| 247 | astate->claims = 0; |
| 248 | arp_announce1(astate); |
| 249 | } |
| 250 | |
| 251 | static void |
| 252 | arp_probed(void *arg) |
| 253 | { |
| 254 | struct arp_state *astate = arg; |
| 255 | |
| 256 | astate->probed_cb(astate); |
| 257 | } |
| 258 | |
| 259 | static void |
| 260 | arp_probe1(void *arg) |
| 261 | { |
| 262 | struct arp_state *astate = arg; |
| 263 | struct interface *ifp = astate->iface; |
| 264 | struct timespec tv; |
| 265 | |
| 266 | if (++astate->probes < PROBE_NUM) { |
| 267 | tv.tv_sec = PROBE_MIN; |
| 268 | tv.tv_nsec = (suseconds_t)arc4random_uniform( |
| 269 | (PROBE_MAX - PROBE_MIN) * NSEC_PER_SEC); |
| 270 | timespecnorm(&tv); |
| 271 | eloop_timeout_add_tv(ifp->ctx->eloop, &tv, arp_probe1, astate); |
| 272 | } else { |
| 273 | tv.tv_sec = ANNOUNCE_WAIT; |
| 274 | tv.tv_nsec = 0; |
| 275 | eloop_timeout_add_tv(ifp->ctx->eloop, &tv, arp_probed, astate); |
| 276 | } |
| 277 | logger(ifp->ctx, LOG_DEBUG, |
| 278 | "%s: ARP probing %s (%d of %d), next in %0.1f seconds", |
| 279 | ifp->name, inet_ntoa(astate->addr), |
| 280 | astate->probes ? astate->probes : PROBE_NUM, PROBE_NUM, |
| 281 | timespec_to_double(&tv)); |
| 282 | if (arp_request(ifp, 0, astate->addr.s_addr) == -1) |
| 283 | logger(ifp->ctx, LOG_ERR, "send_arp: %m"); |
| 284 | } |
| 285 | |
| 286 | void |
| 287 | arp_probe(struct arp_state *astate) |
| 288 | { |
| 289 | |
| 290 | arp_open(astate->iface); |
| 291 | astate->probes = 0; |
| 292 | logger(astate->iface->ctx, LOG_DEBUG, "%s: probing for %s", |
| 293 | astate->iface->name, inet_ntoa(astate->addr)); |
| 294 | arp_probe1(astate); |
| 295 | } |
| 296 | |
| 297 | static struct arp_state * |
| 298 | arp_find(struct interface *ifp, const struct in_addr *addr) |
| 299 | { |
| 300 | struct arp_state *astate; |
| 301 | struct dhcp_state *state; |
| 302 | |
| 303 | state = D_STATE(ifp); |
| 304 | TAILQ_FOREACH(astate, &state->arp_states, next) { |
| 305 | if (astate->addr.s_addr == addr->s_addr && astate->iface == ifp) |
| 306 | return astate; |
| 307 | } |
| 308 | errno = ESRCH; |
| 309 | return NULL; |
| 310 | } |
| 311 | |
| 312 | struct arp_state * |
| 313 | arp_new(struct interface *ifp, const struct in_addr *addr) |
| 314 | { |
| 315 | struct arp_state *astate; |
| 316 | struct dhcp_state *state; |
| 317 | |
| 318 | if (addr && (astate = arp_find(ifp, addr))) |
| 319 | return astate; |
| 320 | |
| 321 | if ((astate = calloc(1, sizeof(*astate))) == NULL) { |
| 322 | logger(ifp->ctx, LOG_ERR, "%s: %s: %m", ifp->name, __func__); |
| 323 | return NULL; |
| 324 | } |
| 325 | state = D_STATE(ifp); |
| 326 | astate->iface = ifp; |
| 327 | if (addr) |
| 328 | astate->addr = *addr; |
| 329 | TAILQ_INSERT_TAIL(&state->arp_states, astate, next); |
| 330 | return astate; |
| 331 | } |
| 332 | |
| 333 | void |
| 334 | arp_cancel(struct arp_state *astate) |
| 335 | { |
| 336 | |
| 337 | eloop_timeout_delete(astate->iface->ctx->eloop, NULL, astate); |
| 338 | } |
| 339 | |
| 340 | void |
| 341 | arp_free(struct arp_state *astate) |
| 342 | { |
| 343 | struct dhcp_state *state; |
| 344 | |
| 345 | if (astate) { |
| 346 | eloop_timeout_delete(astate->iface->ctx->eloop, NULL, astate); |
| 347 | state = D_STATE(astate->iface); |
| 348 | TAILQ_REMOVE(&state->arp_states, astate, next); |
| 349 | if (state->arp_ipv4ll == astate) { |
| 350 | ipv4ll_stop(astate->iface); |
| 351 | state->arp_ipv4ll = NULL; |
| 352 | } |
| 353 | free(astate); |
| 354 | } |
| 355 | } |
| 356 | |
| 357 | void |
| 358 | arp_free_but(struct arp_state *astate) |
| 359 | { |
| 360 | struct arp_state *p, *n; |
| 361 | struct dhcp_state *state; |
| 362 | |
| 363 | state = D_STATE(astate->iface); |
| 364 | TAILQ_FOREACH_SAFE(p, &state->arp_states, next, n) { |
| 365 | if (p != astate) |
| 366 | arp_free(p); |
| 367 | } |
| 368 | } |
| 369 | |
| 370 | void |
| 371 | arp_close(struct interface *ifp) |
| 372 | { |
| 373 | struct dhcp_state *state = D_STATE(ifp); |
| 374 | struct arp_state *astate; |
| 375 | |
| 376 | if (state == NULL) |
| 377 | return; |
| 378 | |
| 379 | if (state->arp_fd != -1) { |
| 380 | eloop_event_delete(ifp->ctx->eloop, state->arp_fd, 0); |
| 381 | close(state->arp_fd); |
| 382 | state->arp_fd = -1; |
| 383 | } |
| 384 | |
| 385 | while ((astate = TAILQ_FIRST(&state->arp_states))) { |
| 386 | #ifndef __clang_analyzer__ |
| 387 | /* clang guard needed for a more compex variant on this bug: |
| 388 | * http://llvm.org/bugs/show_bug.cgi?id=18222 */ |
| 389 | arp_free(astate); |
| 390 | #endif |
| 391 | } |
| 392 | } |
| 393 | |
| 394 | void |
| 395 | arp_handleifa(int cmd, struct interface *ifp, const struct in_addr *addr, |
| 396 | int flags) |
| 397 | { |
| 398 | #ifdef IN_IFF_DUPLICATED |
| 399 | struct dhcp_state *state = D_STATE(ifp); |
| 400 | struct arp_state *astate, *asn; |
| 401 | |
| 402 | if (cmd != RTM_NEWADDR || (state = D_STATE(ifp)) == NULL) |
| 403 | return; |
| 404 | |
| 405 | TAILQ_FOREACH_SAFE(astate, &state->arp_states, next, asn) { |
| 406 | if (astate->addr.s_addr == addr->s_addr) { |
| 407 | if (flags & IN_IFF_DUPLICATED) { |
| 408 | if (astate->conflicted_cb) |
| 409 | astate->conflicted_cb(astate, NULL); |
| 410 | } else if (!(flags & IN_IFF_NOTUSEABLE)) { |
| 411 | if (astate->probed_cb) |
| 412 | astate->probed_cb(astate); |
| 413 | } |
| 414 | } |
| 415 | } |
| 416 | #else |
| 417 | UNUSED(cmd); |
| 418 | UNUSED(ifp); |
| 419 | UNUSED(addr); |
| 420 | UNUSED(flags); |
| 421 | #endif |
| 422 | } |