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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 | ||
52 | static IPaddr_t ip; | |
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 | */ | |
67 | static IPaddr_t pick(void) | |
68 | { | |
69 | unsigned tmp; | |
70 | ||
71 | do { | |
99e139d5 | 72 | tmp = rand_r(&seed) & IN_CLASSB_HOST; |
d22c338e JH |
73 | } while (tmp > (IN_CLASSB_HOST - 0x0200)); |
74 | return (IPaddr_t) htonl((LINKLOCAL_ADDR + 0x0100) + tmp); | |
75 | } | |
76 | ||
77 | /** | |
78 | * Return milliseconds of random delay, up to "secs" seconds. | |
79 | */ | |
80 | static inline unsigned random_delay_ms(unsigned secs) | |
81 | { | |
99e139d5 | 82 | return rand_r(&seed) % (secs * 1000); |
d22c338e JH |
83 | } |
84 | ||
85 | static void configure_wait(void) | |
86 | { | |
87 | if (timeout_ms == -1) | |
88 | return; | |
89 | ||
90 | /* poll, being ready to adjust current timeout */ | |
91 | if (!timeout_ms) | |
92 | timeout_ms = random_delay_ms(PROBE_WAIT); | |
93 | ||
94 | /* set deadline_ms to the point in time when we timeout */ | |
95 | deadline_ms = MONOTONIC_MS() + timeout_ms; | |
96 | ||
4ef8d53c | 97 | debug_cond(DEBUG_DEV_PKT, "...wait %d %s nprobes=%u, nclaims=%u\n", |
d22c338e JH |
98 | timeout_ms, eth_get_name(), nprobes, nclaims); |
99 | ||
100 | NetSetTimeout(timeout_ms, link_local_timeout); | |
101 | } | |
102 | ||
103 | void link_local_start(void) | |
104 | { | |
105 | ip = getenv_IPaddr("llipaddr"); | |
65b0db83 | 106 | if (ip != 0 && (ntohl(ip) & IN_CLASSB_NET) != LINKLOCAL_ADDR) { |
d22c338e JH |
107 | puts("invalid link address"); |
108 | net_set_state(NETLOOP_FAIL); | |
109 | return; | |
110 | } | |
111 | NetOurSubnetMask = IN_CLASSB_NET; | |
112 | ||
99e139d5 | 113 | seed = seed_mac(); |
d22c338e JH |
114 | if (ip == 0) |
115 | ip = pick(); | |
116 | ||
117 | state = PROBE; | |
118 | timeout_ms = 0; | |
119 | conflicts = 0; | |
120 | nprobes = 0; | |
121 | nclaims = 0; | |
122 | ready = 0; | |
123 | ||
124 | configure_wait(); | |
125 | } | |
126 | ||
127 | static void link_local_timeout(void) | |
128 | { | |
129 | switch (state) { | |
130 | case PROBE: | |
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) { | |
134 | nprobes++; | |
4ef8d53c | 135 | debug_cond(DEBUG_LL_STATE, "probe/%u %s@%pI4\n", |
d22c338e JH |
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); | |
140 | } else { | |
141 | /* Switch to announce state */ | |
142 | state = ANNOUNCE; | |
143 | nclaims = 0; | |
4ef8d53c | 144 | debug_cond(DEBUG_LL_STATE, "announce/%u %s@%pI4\n", |
d22c338e JH |
145 | nclaims, eth_get_name(), &ip); |
146 | arp_raw_request(ip, NetOurEther, ip); | |
147 | timeout_ms = ANNOUNCE_INTERVAL * 1000; | |
148 | } | |
149 | break; | |
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 */ | |
154 | state = ANNOUNCE; | |
155 | nclaims = 0; | |
4ef8d53c | 156 | debug_cond(DEBUG_LL_STATE, "announce/%u %s@%pI4\n", |
d22c338e JH |
157 | nclaims, eth_get_name(), &ip); |
158 | arp_raw_request(ip, NetOurEther, ip); | |
159 | timeout_ms = ANNOUNCE_INTERVAL * 1000; | |
160 | break; | |
161 | case ANNOUNCE: | |
162 | /* timeouts in the ANNOUNCE state mean no conflicting ARP | |
163 | packets have been received, so we can progress through | |
164 | the states */ | |
165 | if (nclaims < ANNOUNCE_NUM) { | |
166 | nclaims++; | |
4ef8d53c | 167 | debug_cond(DEBUG_LL_STATE, "announce/%u %s@%pI4\n", |
d22c338e JH |
168 | nclaims, eth_get_name(), &ip); |
169 | arp_raw_request(ip, NetOurEther, ip); | |
170 | timeout_ms = ANNOUNCE_INTERVAL * 1000; | |
171 | } else { | |
172 | /* Switch to monitor state */ | |
173 | state = MONITOR; | |
174 | printf("Successfully assigned %pI4\n", &ip); | |
175 | NetCopyIP(&NetOurIP, &ip); | |
176 | ready = 1; | |
177 | conflicts = 0; | |
178 | timeout_ms = -1; | |
179 | /* Never timeout in the monitor state */ | |
180 | NetSetTimeout(0, NULL); | |
181 | ||
182 | /* NOTE: all other exit paths should deconfig ... */ | |
183 | net_set_state(NETLOOP_SUCCESS); | |
184 | return; | |
185 | } | |
186 | break; | |
187 | case DEFEND: | |
188 | /* We won! No ARP replies, so just go back to monitor */ | |
189 | state = MONITOR; | |
190 | timeout_ms = -1; | |
191 | conflicts = 0; | |
192 | break; | |
193 | default: | |
194 | /* Invalid, should never happen. Restart the whole protocol */ | |
195 | state = PROBE; | |
196 | ip = pick(); | |
197 | timeout_ms = 0; | |
198 | nprobes = 0; | |
199 | nclaims = 0; | |
200 | break; | |
201 | } | |
202 | configure_wait(); | |
203 | } | |
204 | ||
205 | void link_local_receive_arp(struct arp_hdr *arp, int len) | |
206 | { | |
207 | int source_ip_conflict; | |
208 | int target_ip_conflict; | |
5da7cf81 | 209 | IPaddr_t null_ip = 0; |
d22c338e JH |
210 | |
211 | if (state == DISABLED) | |
212 | return; | |
213 | ||
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 */ | |
4ef8d53c JH |
221 | debug_cond(DEBUG_LL_STATE, |
222 | "missed an expected timeout\n"); | |
d22c338e JH |
223 | timeout_ms = 0; |
224 | } else { | |
4ef8d53c | 225 | debug_cond(DEBUG_INT_STATE, "adjusting timeout\n"); |
d22c338e JH |
226 | timeout_ms = diff | 1; /* never 0 */ |
227 | } | |
228 | } | |
b6841157 | 229 | #if 0 |
230 | /* XXX Don't bother with ethernet link just yet */ | |
d22c338e JH |
231 | if ((fds[0].revents & POLLIN) == 0) { |
232 | if (fds[0].revents & POLLERR) { | |
3fe63839 WD |
233 | /* |
234 | * FIXME: links routinely go down; | |
235 | */ | |
d22c338e JH |
236 | bb_error_msg("iface %s is down", eth_get_name()); |
237 | if (ready) { | |
238 | run(argv, "deconfig", &ip); | |
239 | } | |
240 | return EXIT_FAILURE; | |
241 | } | |
242 | continue; | |
243 | } | |
b6841157 | 244 | #endif |
d22c338e | 245 | |
4ef8d53c | 246 | debug_cond(DEBUG_INT_STATE, "%s recv arp type=%d, op=%d,\n", |
d22c338e JH |
247 | eth_get_name(), ntohs(arp->ar_pro), |
248 | ntohs(arp->ar_op)); | |
4ef8d53c | 249 | debug_cond(DEBUG_INT_STATE, "\tsource=%pM %pI4\n", |
d22c338e JH |
250 | &arp->ar_sha, |
251 | &arp->ar_spa); | |
4ef8d53c | 252 | debug_cond(DEBUG_INT_STATE, "\ttarget=%pM %pI4\n", |
d22c338e JH |
253 | &arp->ar_tha, |
254 | &arp->ar_tpa); | |
255 | ||
256 | if (arp->ar_op != htons(ARPOP_REQUEST) | |
257 | && arp->ar_op != htons(ARPOP_REPLY) | |
258 | ) { | |
259 | configure_wait(); | |
260 | return; | |
261 | } | |
262 | ||
263 | source_ip_conflict = 0; | |
264 | target_ip_conflict = 0; | |
265 | ||
266 | if (memcmp(&arp->ar_spa, &ip, ARP_PLEN) == 0 | |
267 | && memcmp(&arp->ar_sha, NetOurEther, ARP_HLEN) != 0 | |
268 | ) { | |
269 | source_ip_conflict = 1; | |
270 | } | |
5da7cf81 JH |
271 | |
272 | /* | |
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 | |
277 | * during probe. | |
278 | */ | |
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) { | |
d22c338e JH |
283 | target_ip_conflict = 1; |
284 | } | |
285 | ||
4ef8d53c JH |
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); | |
d22c338e JH |
289 | switch (state) { |
290 | case PROBE: | |
291 | case ANNOUNCE: | |
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) { | |
295 | conflicts++; | |
296 | state = PROBE; | |
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; | |
301 | } | |
302 | ||
303 | /* restart the whole protocol */ | |
304 | ip = pick(); | |
305 | timeout_ms = 0; | |
306 | nprobes = 0; | |
307 | nclaims = 0; | |
308 | } | |
309 | break; | |
310 | case MONITOR: | |
311 | /* If a conflict, we try to defend with a single ARP probe */ | |
312 | if (source_ip_conflict) { | |
313 | debug("monitor conflict -- defending\n"); | |
314 | state = DEFEND; | |
315 | timeout_ms = DEFEND_INTERVAL * 1000; | |
316 | arp_raw_request(ip, NetOurEther, ip); | |
317 | } | |
318 | break; | |
319 | case DEFEND: | |
320 | /* Well, we tried. Start over (on conflict) */ | |
321 | if (source_ip_conflict) { | |
322 | state = PROBE; | |
323 | debug("defend conflict -- starting over\n"); | |
324 | ready = 0; | |
325 | NetOurIP = 0; | |
326 | ||
327 | /* restart the whole protocol */ | |
328 | ip = pick(); | |
329 | timeout_ms = 0; | |
330 | nprobes = 0; | |
331 | nclaims = 0; | |
332 | } | |
333 | break; | |
334 | default: | |
335 | /* Invalid, should never happen. Restart the whole protocol */ | |
336 | debug("invalid state -- starting over\n"); | |
337 | state = PROBE; | |
338 | ip = pick(); | |
339 | timeout_ms = 0; | |
340 | nprobes = 0; | |
341 | nclaims = 0; | |
342 | break; | |
343 | } | |
344 | configure_wait(); | |
345 | } |