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d22c338e JH |
1 | /* |
2 | * RFC3927 ZeroConf IPv4 Link-Local addressing | |
3 | * (see <http://www.zeroconf.org/>) | |
4 | * | |
5 | * Copied from BusyBox - networking/zcip.c | |
6 | * | |
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 | |
10 | * | |
11 | * Licensed under the GPL v2 or later | |
12 | */ | |
13 | ||
14 | #include <common.h> | |
15 | #include <net.h> | |
16 | #include "arp.h" | |
17 | #include "net_rand.h" | |
18 | ||
19 | /* We don't need more than 32 bits of the counter */ | |
20 | #define MONOTONIC_MS() ((unsigned)get_timer(0) * (1000 / CONFIG_SYS_HZ)) | |
21 | ||
22 | enum { | |
23 | /* 169.254.0.0 */ | |
24 | LINKLOCAL_ADDR = 0xa9fe0000, | |
25 | ||
26 | IN_CLASSB_NET = 0xffff0000, | |
27 | IN_CLASSB_HOST = 0x0000ffff, | |
28 | ||
29 | /* protocol timeout parameters, specified in seconds */ | |
30 | PROBE_WAIT = 1, | |
31 | PROBE_MIN = 1, | |
32 | PROBE_MAX = 2, | |
33 | PROBE_NUM = 3, | |
34 | MAX_CONFLICTS = 10, | |
35 | RATE_LIMIT_INTERVAL = 60, | |
36 | ANNOUNCE_WAIT = 2, | |
37 | ANNOUNCE_NUM = 2, | |
38 | ANNOUNCE_INTERVAL = 2, | |
39 | DEFEND_INTERVAL = 10 | |
40 | }; | |
41 | ||
42 | /* States during the configuration process. */ | |
43 | static enum ll_state_t { | |
44 | PROBE = 0, | |
45 | RATE_LIMIT_PROBE, | |
46 | ANNOUNCE, | |
47 | MONITOR, | |
48 | DEFEND, | |
49 | DISABLED | |
50 | } state = DISABLED; | |
51 | ||
049a95a7 | 52 | static struct in_addr ip; |
d22c338e JH |
53 | static int timeout_ms = -1; |
54 | static unsigned deadline_ms; | |
55 | static unsigned conflicts; | |
56 | static unsigned nprobes; | |
57 | static unsigned nclaims; | |
58 | static int ready; | |
99e139d5 | 59 | static unsigned int seed; |
d22c338e JH |
60 | |
61 | static void link_local_timeout(void); | |
62 | ||
63 | /** | |
64 | * Pick a random link local IP address on 169.254/16, except that | |
65 | * the first and last 256 addresses are reserved. | |
66 | */ | |
049a95a7 | 67 | static struct in_addr pick(void) |
d22c338e JH |
68 | { |
69 | unsigned tmp; | |
049a95a7 | 70 | struct in_addr ip; |
d22c338e JH |
71 | |
72 | do { | |
99e139d5 | 73 | tmp = rand_r(&seed) & IN_CLASSB_HOST; |
d22c338e | 74 | } while (tmp > (IN_CLASSB_HOST - 0x0200)); |
049a95a7 JH |
75 | ip.s_addr = htonl((LINKLOCAL_ADDR + 0x0100) + tmp); |
76 | return ip; | |
d22c338e JH |
77 | } |
78 | ||
79 | /** | |
80 | * Return milliseconds of random delay, up to "secs" seconds. | |
81 | */ | |
82 | static inline unsigned random_delay_ms(unsigned secs) | |
83 | { | |
99e139d5 | 84 | return rand_r(&seed) % (secs * 1000); |
d22c338e JH |
85 | } |
86 | ||
87 | static void configure_wait(void) | |
88 | { | |
89 | if (timeout_ms == -1) | |
90 | return; | |
91 | ||
92 | /* poll, being ready to adjust current timeout */ | |
93 | if (!timeout_ms) | |
94 | timeout_ms = random_delay_ms(PROBE_WAIT); | |
95 | ||
96 | /* set deadline_ms to the point in time when we timeout */ | |
97 | deadline_ms = MONOTONIC_MS() + timeout_ms; | |
98 | ||
4ef8d53c | 99 | debug_cond(DEBUG_DEV_PKT, "...wait %d %s nprobes=%u, nclaims=%u\n", |
d22c338e JH |
100 | timeout_ms, eth_get_name(), nprobes, nclaims); |
101 | ||
102 | NetSetTimeout(timeout_ms, link_local_timeout); | |
103 | } | |
104 | ||
105 | void link_local_start(void) | |
106 | { | |
049a95a7 JH |
107 | ip = getenv_ip("llipaddr"); |
108 | if (ip.s_addr != 0 && | |
109 | (ntohl(ip.s_addr) & IN_CLASSB_NET) != LINKLOCAL_ADDR) { | |
d22c338e JH |
110 | puts("invalid link address"); |
111 | net_set_state(NETLOOP_FAIL); | |
112 | return; | |
113 | } | |
049a95a7 | 114 | net_netmask.s_addr = IN_CLASSB_NET; |
d22c338e | 115 | |
99e139d5 | 116 | seed = seed_mac(); |
049a95a7 | 117 | if (ip.s_addr == 0) |
d22c338e JH |
118 | ip = pick(); |
119 | ||
120 | state = PROBE; | |
121 | timeout_ms = 0; | |
122 | conflicts = 0; | |
123 | nprobes = 0; | |
124 | nclaims = 0; | |
125 | ready = 0; | |
126 | ||
127 | configure_wait(); | |
128 | } | |
129 | ||
130 | static void link_local_timeout(void) | |
131 | { | |
132 | switch (state) { | |
133 | case PROBE: | |
134 | /* timeouts in the PROBE state mean no conflicting ARP packets | |
135 | have been received, so we can progress through the states */ | |
136 | if (nprobes < PROBE_NUM) { | |
049a95a7 JH |
137 | struct in_addr zero_ip = {.s_addr = 0}; |
138 | ||
d22c338e | 139 | nprobes++; |
4ef8d53c | 140 | debug_cond(DEBUG_LL_STATE, "probe/%u %s@%pI4\n", |
d22c338e | 141 | nprobes, eth_get_name(), &ip); |
0adb5b76 | 142 | arp_raw_request(zero_ip, net_null_ethaddr, ip); |
d22c338e JH |
143 | timeout_ms = PROBE_MIN * 1000; |
144 | timeout_ms += random_delay_ms(PROBE_MAX - PROBE_MIN); | |
145 | } else { | |
146 | /* Switch to announce state */ | |
147 | state = ANNOUNCE; | |
148 | nclaims = 0; | |
4ef8d53c | 149 | debug_cond(DEBUG_LL_STATE, "announce/%u %s@%pI4\n", |
d22c338e | 150 | nclaims, eth_get_name(), &ip); |
0adb5b76 | 151 | arp_raw_request(ip, net_ethaddr, ip); |
d22c338e JH |
152 | timeout_ms = ANNOUNCE_INTERVAL * 1000; |
153 | } | |
154 | break; | |
155 | case RATE_LIMIT_PROBE: | |
156 | /* timeouts in the RATE_LIMIT_PROBE state mean no conflicting | |
157 | ARP packets have been received, so we can move immediately | |
158 | to the announce state */ | |
159 | state = ANNOUNCE; | |
160 | nclaims = 0; | |
4ef8d53c | 161 | debug_cond(DEBUG_LL_STATE, "announce/%u %s@%pI4\n", |
d22c338e | 162 | nclaims, eth_get_name(), &ip); |
0adb5b76 | 163 | arp_raw_request(ip, net_ethaddr, ip); |
d22c338e JH |
164 | timeout_ms = ANNOUNCE_INTERVAL * 1000; |
165 | break; | |
166 | case ANNOUNCE: | |
167 | /* timeouts in the ANNOUNCE state mean no conflicting ARP | |
168 | packets have been received, so we can progress through | |
169 | the states */ | |
170 | if (nclaims < ANNOUNCE_NUM) { | |
171 | nclaims++; | |
4ef8d53c | 172 | debug_cond(DEBUG_LL_STATE, "announce/%u %s@%pI4\n", |
d22c338e | 173 | nclaims, eth_get_name(), &ip); |
0adb5b76 | 174 | arp_raw_request(ip, net_ethaddr, ip); |
d22c338e JH |
175 | timeout_ms = ANNOUNCE_INTERVAL * 1000; |
176 | } else { | |
177 | /* Switch to monitor state */ | |
178 | state = MONITOR; | |
179 | printf("Successfully assigned %pI4\n", &ip); | |
049a95a7 | 180 | net_copy_ip(&net_ip, &ip); |
d22c338e JH |
181 | ready = 1; |
182 | conflicts = 0; | |
183 | timeout_ms = -1; | |
184 | /* Never timeout in the monitor state */ | |
185 | NetSetTimeout(0, NULL); | |
186 | ||
187 | /* NOTE: all other exit paths should deconfig ... */ | |
188 | net_set_state(NETLOOP_SUCCESS); | |
189 | return; | |
190 | } | |
191 | break; | |
192 | case DEFEND: | |
193 | /* We won! No ARP replies, so just go back to monitor */ | |
194 | state = MONITOR; | |
195 | timeout_ms = -1; | |
196 | conflicts = 0; | |
197 | break; | |
198 | default: | |
199 | /* Invalid, should never happen. Restart the whole protocol */ | |
200 | state = PROBE; | |
201 | ip = pick(); | |
202 | timeout_ms = 0; | |
203 | nprobes = 0; | |
204 | nclaims = 0; | |
205 | break; | |
206 | } | |
207 | configure_wait(); | |
208 | } | |
209 | ||
210 | void link_local_receive_arp(struct arp_hdr *arp, int len) | |
211 | { | |
212 | int source_ip_conflict; | |
213 | int target_ip_conflict; | |
049a95a7 | 214 | struct in_addr null_ip = {.s_addr = 0}; |
d22c338e JH |
215 | |
216 | if (state == DISABLED) | |
217 | return; | |
218 | ||
219 | /* We need to adjust the timeout in case we didn't receive a | |
220 | conflicting packet. */ | |
221 | if (timeout_ms > 0) { | |
222 | unsigned diff = deadline_ms - MONOTONIC_MS(); | |
223 | if ((int)(diff) < 0) { | |
224 | /* Current time is greater than the expected timeout | |
225 | time. This should never happen */ | |
4ef8d53c JH |
226 | debug_cond(DEBUG_LL_STATE, |
227 | "missed an expected timeout\n"); | |
d22c338e JH |
228 | timeout_ms = 0; |
229 | } else { | |
4ef8d53c | 230 | debug_cond(DEBUG_INT_STATE, "adjusting timeout\n"); |
d22c338e JH |
231 | timeout_ms = diff | 1; /* never 0 */ |
232 | } | |
233 | } | |
b6841157 | 234 | #if 0 |
235 | /* XXX Don't bother with ethernet link just yet */ | |
d22c338e JH |
236 | if ((fds[0].revents & POLLIN) == 0) { |
237 | if (fds[0].revents & POLLERR) { | |
3fe63839 WD |
238 | /* |
239 | * FIXME: links routinely go down; | |
240 | */ | |
d22c338e JH |
241 | bb_error_msg("iface %s is down", eth_get_name()); |
242 | if (ready) { | |
243 | run(argv, "deconfig", &ip); | |
244 | } | |
245 | return EXIT_FAILURE; | |
246 | } | |
247 | continue; | |
248 | } | |
b6841157 | 249 | #endif |
d22c338e | 250 | |
4ef8d53c | 251 | debug_cond(DEBUG_INT_STATE, "%s recv arp type=%d, op=%d,\n", |
d22c338e JH |
252 | eth_get_name(), ntohs(arp->ar_pro), |
253 | ntohs(arp->ar_op)); | |
4ef8d53c | 254 | debug_cond(DEBUG_INT_STATE, "\tsource=%pM %pI4\n", |
d22c338e JH |
255 | &arp->ar_sha, |
256 | &arp->ar_spa); | |
4ef8d53c | 257 | debug_cond(DEBUG_INT_STATE, "\ttarget=%pM %pI4\n", |
d22c338e JH |
258 | &arp->ar_tha, |
259 | &arp->ar_tpa); | |
260 | ||
261 | if (arp->ar_op != htons(ARPOP_REQUEST) | |
262 | && arp->ar_op != htons(ARPOP_REPLY) | |
263 | ) { | |
264 | configure_wait(); | |
265 | return; | |
266 | } | |
267 | ||
268 | source_ip_conflict = 0; | |
269 | target_ip_conflict = 0; | |
270 | ||
0adb5b76 JH |
271 | if (memcmp(&arp->ar_spa, &ip, ARP_PLEN) == 0 && |
272 | memcmp(&arp->ar_sha, net_ethaddr, ARP_HLEN) != 0) | |
d22c338e | 273 | source_ip_conflict = 1; |
5da7cf81 JH |
274 | |
275 | /* | |
276 | * According to RFC 3927, section 2.2.1: | |
277 | * Check if packet is an ARP probe by checking for a null source IP | |
278 | * then check that target IP is equal to ours and source hw addr | |
279 | * is not equal to ours. This condition should cause a conflict only | |
280 | * during probe. | |
281 | */ | |
282 | if (arp->ar_op == htons(ARPOP_REQUEST) && | |
283 | memcmp(&arp->ar_spa, &null_ip, ARP_PLEN) == 0 && | |
284 | memcmp(&arp->ar_tpa, &ip, ARP_PLEN) == 0 && | |
0adb5b76 | 285 | memcmp(&arp->ar_sha, net_ethaddr, ARP_HLEN) != 0) { |
d22c338e JH |
286 | target_ip_conflict = 1; |
287 | } | |
288 | ||
4ef8d53c JH |
289 | debug_cond(DEBUG_NET_PKT, |
290 | "state = %d, source ip conflict = %d, target ip conflict = " | |
291 | "%d\n", state, source_ip_conflict, target_ip_conflict); | |
d22c338e JH |
292 | switch (state) { |
293 | case PROBE: | |
294 | case ANNOUNCE: | |
295 | /* When probing or announcing, check for source IP conflicts | |
296 | and other hosts doing ARP probes (target IP conflicts). */ | |
297 | if (source_ip_conflict || target_ip_conflict) { | |
298 | conflicts++; | |
299 | state = PROBE; | |
300 | if (conflicts >= MAX_CONFLICTS) { | |
301 | debug("%s ratelimit\n", eth_get_name()); | |
302 | timeout_ms = RATE_LIMIT_INTERVAL * 1000; | |
303 | state = RATE_LIMIT_PROBE; | |
304 | } | |
305 | ||
306 | /* restart the whole protocol */ | |
307 | ip = pick(); | |
308 | timeout_ms = 0; | |
309 | nprobes = 0; | |
310 | nclaims = 0; | |
311 | } | |
312 | break; | |
313 | case MONITOR: | |
314 | /* If a conflict, we try to defend with a single ARP probe */ | |
315 | if (source_ip_conflict) { | |
316 | debug("monitor conflict -- defending\n"); | |
317 | state = DEFEND; | |
318 | timeout_ms = DEFEND_INTERVAL * 1000; | |
0adb5b76 | 319 | arp_raw_request(ip, net_ethaddr, ip); |
d22c338e JH |
320 | } |
321 | break; | |
322 | case DEFEND: | |
323 | /* Well, we tried. Start over (on conflict) */ | |
324 | if (source_ip_conflict) { | |
325 | state = PROBE; | |
326 | debug("defend conflict -- starting over\n"); | |
327 | ready = 0; | |
049a95a7 | 328 | net_ip.s_addr = 0; |
d22c338e JH |
329 | |
330 | /* restart the whole protocol */ | |
331 | ip = pick(); | |
332 | timeout_ms = 0; | |
333 | nprobes = 0; | |
334 | nclaims = 0; | |
335 | } | |
336 | break; | |
337 | default: | |
338 | /* Invalid, should never happen. Restart the whole protocol */ | |
339 | debug("invalid state -- starting over\n"); | |
340 | state = PROBE; | |
341 | ip = pick(); | |
342 | timeout_ms = 0; | |
343 | nprobes = 0; | |
344 | nclaims = 0; | |
345 | break; | |
346 | } | |
347 | configure_wait(); | |
348 | } |