2 * RFC3927 ZeroConf IPv4 Link-Local addressing
3 * (see <http://www.zeroconf.org/>)
5 * Copied from BusyBox - networking/zcip.c
7 * Copyright (C) 2003 by Arthur van Hoff (avh@strangeberry.com)
8 * Copyright (C) 2004 by David Brownell
9 * Copyright (C) 2010 by Joe Hershberger
11 * Licensed under the GPL v2 or later
19 /* We don't need more than 32 bits of the counter */
20 #define MONOTONIC_MS() ((unsigned)get_timer(0) * (1000 / CONFIG_SYS_HZ))
24 LINKLOCAL_ADDR = 0xa9fe0000,
26 IN_CLASSB_NET = 0xffff0000,
27 IN_CLASSB_HOST = 0x0000ffff,
29 /* protocol timeout parameters, specified in seconds */
35 RATE_LIMIT_INTERVAL = 60,
38 ANNOUNCE_INTERVAL = 2,
42 /* States during the configuration process. */
43 static enum ll_state_t {
53 static int timeout_ms = -1;
54 static unsigned deadline_ms;
55 static unsigned conflicts;
56 static unsigned nprobes;
57 static unsigned nclaims;
59 static unsigned int seed;
61 static void link_local_timeout(void);
64 * Pick a random link local IP address on 169.254/16, except that
65 * the first and last 256 addresses are reserved.
67 static IPaddr_t pick(void)
72 tmp = rand_r(&seed) & IN_CLASSB_HOST;
73 } while (tmp > (IN_CLASSB_HOST - 0x0200));
74 return (IPaddr_t) htonl((LINKLOCAL_ADDR + 0x0100) + tmp);
78 * Return milliseconds of random delay, up to "secs" seconds.
80 static inline unsigned random_delay_ms(unsigned secs)
82 return rand_r(&seed) % (secs * 1000);
85 static void configure_wait(void)
90 /* poll, being ready to adjust current timeout */
92 timeout_ms = random_delay_ms(PROBE_WAIT);
94 /* set deadline_ms to the point in time when we timeout */
95 deadline_ms = MONOTONIC_MS() + timeout_ms;
97 debug_cond(DEBUG_DEV_PKT, "...wait %d %s nprobes=%u, nclaims=%u\n",
98 timeout_ms, eth_get_name(), nprobes, nclaims);
100 NetSetTimeout(timeout_ms, link_local_timeout);
103 void link_local_start(void)
105 ip = getenv_IPaddr("llipaddr");
106 if (ip != 0 && (ntohl(ip) & IN_CLASSB_NET) != LINKLOCAL_ADDR) {
107 puts("invalid link address");
108 net_set_state(NETLOOP_FAIL);
111 NetOurSubnetMask = IN_CLASSB_NET;
127 static void link_local_timeout(void)
131 /* timeouts in the PROBE state mean no conflicting ARP packets
132 have been received, so we can progress through the states */
133 if (nprobes < PROBE_NUM) {
135 debug_cond(DEBUG_LL_STATE, "probe/%u %s@%pI4\n",
136 nprobes, eth_get_name(), &ip);
137 arp_raw_request(0, NetEtherNullAddr, ip);
138 timeout_ms = PROBE_MIN * 1000;
139 timeout_ms += random_delay_ms(PROBE_MAX - PROBE_MIN);
141 /* Switch to announce state */
144 debug_cond(DEBUG_LL_STATE, "announce/%u %s@%pI4\n",
145 nclaims, eth_get_name(), &ip);
146 arp_raw_request(ip, NetOurEther, ip);
147 timeout_ms = ANNOUNCE_INTERVAL * 1000;
150 case RATE_LIMIT_PROBE:
151 /* timeouts in the RATE_LIMIT_PROBE state mean no conflicting
152 ARP packets have been received, so we can move immediately
153 to the announce state */
156 debug_cond(DEBUG_LL_STATE, "announce/%u %s@%pI4\n",
157 nclaims, eth_get_name(), &ip);
158 arp_raw_request(ip, NetOurEther, ip);
159 timeout_ms = ANNOUNCE_INTERVAL * 1000;
162 /* timeouts in the ANNOUNCE state mean no conflicting ARP
163 packets have been received, so we can progress through
165 if (nclaims < ANNOUNCE_NUM) {
167 debug_cond(DEBUG_LL_STATE, "announce/%u %s@%pI4\n",
168 nclaims, eth_get_name(), &ip);
169 arp_raw_request(ip, NetOurEther, ip);
170 timeout_ms = ANNOUNCE_INTERVAL * 1000;
172 /* Switch to monitor state */
174 printf("Successfully assigned %pI4\n", &ip);
175 NetCopyIP(&NetOurIP, &ip);
179 /* Never timeout in the monitor state */
180 NetSetTimeout(0, NULL);
182 /* NOTE: all other exit paths should deconfig ... */
183 net_set_state(NETLOOP_SUCCESS);
188 /* We won! No ARP replies, so just go back to monitor */
194 /* Invalid, should never happen. Restart the whole protocol */
205 void link_local_receive_arp(struct arp_hdr *arp, int len)
207 int source_ip_conflict;
208 int target_ip_conflict;
209 IPaddr_t null_ip = 0;
211 if (state == DISABLED)
214 /* We need to adjust the timeout in case we didn't receive a
215 conflicting packet. */
216 if (timeout_ms > 0) {
217 unsigned diff = deadline_ms - MONOTONIC_MS();
218 if ((int)(diff) < 0) {
219 /* Current time is greater than the expected timeout
220 time. This should never happen */
221 debug_cond(DEBUG_LL_STATE,
222 "missed an expected timeout\n");
225 debug_cond(DEBUG_INT_STATE, "adjusting timeout\n");
226 timeout_ms = diff | 1; /* never 0 */
230 /* XXX Don't bother with ethernet link just yet */
231 if ((fds[0].revents & POLLIN) == 0) {
232 if (fds[0].revents & POLLERR) {
234 * FIXME: links routinely go down;
236 bb_error_msg("iface %s is down", eth_get_name());
238 run(argv, "deconfig", &ip);
246 debug_cond(DEBUG_INT_STATE, "%s recv arp type=%d, op=%d,\n",
247 eth_get_name(), ntohs(arp->ar_pro),
249 debug_cond(DEBUG_INT_STATE, "\tsource=%pM %pI4\n",
252 debug_cond(DEBUG_INT_STATE, "\ttarget=%pM %pI4\n",
256 if (arp->ar_op != htons(ARPOP_REQUEST)
257 && arp->ar_op != htons(ARPOP_REPLY)
263 source_ip_conflict = 0;
264 target_ip_conflict = 0;
266 if (memcmp(&arp->ar_spa, &ip, ARP_PLEN) == 0
267 && memcmp(&arp->ar_sha, NetOurEther, ARP_HLEN) != 0
269 source_ip_conflict = 1;
273 * According to RFC 3927, section 2.2.1:
274 * Check if packet is an ARP probe by checking for a null source IP
275 * then check that target IP is equal to ours and source hw addr
276 * is not equal to ours. This condition should cause a conflict only
279 if (arp->ar_op == htons(ARPOP_REQUEST) &&
280 memcmp(&arp->ar_spa, &null_ip, ARP_PLEN) == 0 &&
281 memcmp(&arp->ar_tpa, &ip, ARP_PLEN) == 0 &&
282 memcmp(&arp->ar_sha, NetOurEther, ARP_HLEN) != 0) {
283 target_ip_conflict = 1;
286 debug_cond(DEBUG_NET_PKT,
287 "state = %d, source ip conflict = %d, target ip conflict = "
288 "%d\n", state, source_ip_conflict, target_ip_conflict);
292 /* When probing or announcing, check for source IP conflicts
293 and other hosts doing ARP probes (target IP conflicts). */
294 if (source_ip_conflict || target_ip_conflict) {
297 if (conflicts >= MAX_CONFLICTS) {
298 debug("%s ratelimit\n", eth_get_name());
299 timeout_ms = RATE_LIMIT_INTERVAL * 1000;
300 state = RATE_LIMIT_PROBE;
303 /* restart the whole protocol */
311 /* If a conflict, we try to defend with a single ARP probe */
312 if (source_ip_conflict) {
313 debug("monitor conflict -- defending\n");
315 timeout_ms = DEFEND_INTERVAL * 1000;
316 arp_raw_request(ip, NetOurEther, ip);
320 /* Well, we tried. Start over (on conflict) */
321 if (source_ip_conflict) {
323 debug("defend conflict -- starting over\n");
327 /* restart the whole protocol */
335 /* Invalid, should never happen. Restart the whole protocol */
336 debug("invalid state -- starting over\n");