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;
60 static void link_local_timeout(void);
63 * Pick a random link local IP address on 169.254/16, except that
64 * the first and last 256 addresses are reserved.
66 static IPaddr_t pick(void)
71 tmp = rand() & IN_CLASSB_HOST;
72 } while (tmp > (IN_CLASSB_HOST - 0x0200));
73 return (IPaddr_t) htonl((LINKLOCAL_ADDR + 0x0100) + tmp);
77 * Return milliseconds of random delay, up to "secs" seconds.
79 static inline unsigned random_delay_ms(unsigned secs)
81 return rand() % (secs * 1000);
84 static void configure_wait(void)
89 /* poll, being ready to adjust current timeout */
91 timeout_ms = random_delay_ms(PROBE_WAIT);
93 /* set deadline_ms to the point in time when we timeout */
94 deadline_ms = MONOTONIC_MS() + timeout_ms;
96 debug("...wait %d %s nprobes=%u, nclaims=%u\n",
97 timeout_ms, eth_get_name(), nprobes, nclaims);
99 NetSetTimeout(timeout_ms, link_local_timeout);
102 void link_local_start(void)
104 ip = getenv_IPaddr("llipaddr");
105 if (ip != 0 && (ip & IN_CLASSB_NET) != LINKLOCAL_ADDR) {
106 puts("invalid link address");
107 net_set_state(NETLOOP_FAIL);
110 NetOurSubnetMask = IN_CLASSB_NET;
126 static void link_local_timeout(void)
130 /* timeouts in the PROBE state mean no conflicting ARP packets
131 have been received, so we can progress through the states */
132 if (nprobes < PROBE_NUM) {
134 debug("probe/%u %s@%pI4\n",
135 nprobes, eth_get_name(), &ip);
136 arp_raw_request(0, NetEtherNullAddr, ip);
137 timeout_ms = PROBE_MIN * 1000;
138 timeout_ms += random_delay_ms(PROBE_MAX - PROBE_MIN);
140 /* Switch to announce state */
143 debug("announce/%u %s@%pI4\n",
144 nclaims, eth_get_name(), &ip);
145 arp_raw_request(ip, NetOurEther, ip);
146 timeout_ms = ANNOUNCE_INTERVAL * 1000;
149 case RATE_LIMIT_PROBE:
150 /* timeouts in the RATE_LIMIT_PROBE state mean no conflicting
151 ARP packets have been received, so we can move immediately
152 to the announce state */
155 debug("announce/%u %s@%pI4\n",
156 nclaims, eth_get_name(), &ip);
157 arp_raw_request(ip, NetOurEther, ip);
158 timeout_ms = ANNOUNCE_INTERVAL * 1000;
161 /* timeouts in the ANNOUNCE state mean no conflicting ARP
162 packets have been received, so we can progress through
164 if (nclaims < ANNOUNCE_NUM) {
166 debug("announce/%u %s@%pI4\n",
167 nclaims, eth_get_name(), &ip);
168 arp_raw_request(ip, NetOurEther, ip);
169 timeout_ms = ANNOUNCE_INTERVAL * 1000;
171 /* Switch to monitor state */
173 printf("Successfully assigned %pI4\n", &ip);
174 NetCopyIP(&NetOurIP, &ip);
178 /* Never timeout in the monitor state */
179 NetSetTimeout(0, NULL);
181 /* NOTE: all other exit paths should deconfig ... */
182 net_set_state(NETLOOP_SUCCESS);
187 /* We won! No ARP replies, so just go back to monitor */
193 /* Invalid, should never happen. Restart the whole protocol */
204 void link_local_receive_arp(struct arp_hdr *arp, int len)
206 int source_ip_conflict;
207 int target_ip_conflict;
209 if (state == DISABLED)
212 /* We need to adjust the timeout in case we didn't receive a
213 conflicting packet. */
214 if (timeout_ms > 0) {
215 unsigned diff = deadline_ms - MONOTONIC_MS();
216 if ((int)(diff) < 0) {
217 /* Current time is greater than the expected timeout
218 time. This should never happen */
219 debug("missed an expected timeout\n");
222 debug("adjusting timeout\n");
223 timeout_ms = diff | 1; /* never 0 */
227 * XXX Don't bother with ethernet link just yet
228 if ((fds[0].revents & POLLIN) == 0) {
229 if (fds[0].revents & POLLERR) {
230 // FIXME: links routinely go down;
231 // this shouldn't necessarily exit.
232 bb_error_msg("iface %s is down", eth_get_name());
234 run(argv, "deconfig", &ip);
242 debug("%s recv arp type=%d, op=%d,\n",
243 eth_get_name(), ntohs(arp->ar_pro),
245 debug("\tsource=%pM %pI4\n",
248 debug("\ttarget=%pM %pI4\n",
252 if (arp->ar_op != htons(ARPOP_REQUEST)
253 && arp->ar_op != htons(ARPOP_REPLY)
259 source_ip_conflict = 0;
260 target_ip_conflict = 0;
262 if (memcmp(&arp->ar_spa, &ip, ARP_PLEN) == 0
263 && memcmp(&arp->ar_sha, NetOurEther, ARP_HLEN) != 0
265 source_ip_conflict = 1;
267 if (arp->ar_op == htons(ARPOP_REQUEST)
268 && memcmp(&arp->ar_tpa, &ip, ARP_PLEN) == 0
269 && memcmp(&arp->ar_tha, NetOurEther, ARP_HLEN) != 0
271 target_ip_conflict = 1;
274 debug("state = %d, source ip conflict = %d, target ip conflict = %d\n",
275 state, source_ip_conflict, target_ip_conflict);
279 /* When probing or announcing, check for source IP conflicts
280 and other hosts doing ARP probes (target IP conflicts). */
281 if (source_ip_conflict || target_ip_conflict) {
284 if (conflicts >= MAX_CONFLICTS) {
285 debug("%s ratelimit\n", eth_get_name());
286 timeout_ms = RATE_LIMIT_INTERVAL * 1000;
287 state = RATE_LIMIT_PROBE;
290 /* restart the whole protocol */
298 /* If a conflict, we try to defend with a single ARP probe */
299 if (source_ip_conflict) {
300 debug("monitor conflict -- defending\n");
302 timeout_ms = DEFEND_INTERVAL * 1000;
303 arp_raw_request(ip, NetOurEther, ip);
307 /* Well, we tried. Start over (on conflict) */
308 if (source_ip_conflict) {
310 debug("defend conflict -- starting over\n");
314 /* restart the whole protocol */
322 /* Invalid, should never happen. Restart the whole protocol */
323 debug("invalid state -- starting over\n");