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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; | |
59 | ||
60 | static void link_local_timeout(void); | |
61 | ||
62 | /** | |
63 | * Pick a random link local IP address on 169.254/16, except that | |
64 | * the first and last 256 addresses are reserved. | |
65 | */ | |
66 | static IPaddr_t pick(void) | |
67 | { | |
68 | unsigned tmp; | |
69 | ||
70 | do { | |
71 | tmp = rand() & IN_CLASSB_HOST; | |
72 | } while (tmp > (IN_CLASSB_HOST - 0x0200)); | |
73 | return (IPaddr_t) htonl((LINKLOCAL_ADDR + 0x0100) + tmp); | |
74 | } | |
75 | ||
76 | /** | |
77 | * Return milliseconds of random delay, up to "secs" seconds. | |
78 | */ | |
79 | static inline unsigned random_delay_ms(unsigned secs) | |
80 | { | |
81 | return rand() % (secs * 1000); | |
82 | } | |
83 | ||
84 | static void configure_wait(void) | |
85 | { | |
86 | if (timeout_ms == -1) | |
87 | return; | |
88 | ||
89 | /* poll, being ready to adjust current timeout */ | |
90 | if (!timeout_ms) | |
91 | timeout_ms = random_delay_ms(PROBE_WAIT); | |
92 | ||
93 | /* set deadline_ms to the point in time when we timeout */ | |
94 | deadline_ms = MONOTONIC_MS() + timeout_ms; | |
95 | ||
96 | debug("...wait %d %s nprobes=%u, nclaims=%u\n", | |
97 | timeout_ms, eth_get_name(), nprobes, nclaims); | |
98 | ||
99 | NetSetTimeout(timeout_ms, link_local_timeout); | |
100 | } | |
101 | ||
102 | void link_local_start(void) | |
103 | { | |
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); | |
108 | return; | |
109 | } | |
110 | NetOurSubnetMask = IN_CLASSB_NET; | |
111 | ||
112 | srand_mac(); | |
113 | if (ip == 0) | |
114 | ip = pick(); | |
115 | ||
116 | state = PROBE; | |
117 | timeout_ms = 0; | |
118 | conflicts = 0; | |
119 | nprobes = 0; | |
120 | nclaims = 0; | |
121 | ready = 0; | |
122 | ||
123 | configure_wait(); | |
124 | } | |
125 | ||
126 | static void link_local_timeout(void) | |
127 | { | |
128 | switch (state) { | |
129 | case PROBE: | |
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) { | |
133 | nprobes++; | |
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); | |
139 | } else { | |
140 | /* Switch to announce state */ | |
141 | state = ANNOUNCE; | |
142 | nclaims = 0; | |
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; | |
147 | } | |
148 | break; | |
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 */ | |
153 | state = ANNOUNCE; | |
154 | nclaims = 0; | |
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; | |
159 | break; | |
160 | case ANNOUNCE: | |
161 | /* timeouts in the ANNOUNCE state mean no conflicting ARP | |
162 | packets have been received, so we can progress through | |
163 | the states */ | |
164 | if (nclaims < ANNOUNCE_NUM) { | |
165 | nclaims++; | |
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; | |
170 | } else { | |
171 | /* Switch to monitor state */ | |
172 | state = MONITOR; | |
173 | printf("Successfully assigned %pI4\n", &ip); | |
174 | NetCopyIP(&NetOurIP, &ip); | |
175 | ready = 1; | |
176 | conflicts = 0; | |
177 | timeout_ms = -1; | |
178 | /* Never timeout in the monitor state */ | |
179 | NetSetTimeout(0, NULL); | |
180 | ||
181 | /* NOTE: all other exit paths should deconfig ... */ | |
182 | net_set_state(NETLOOP_SUCCESS); | |
183 | return; | |
184 | } | |
185 | break; | |
186 | case DEFEND: | |
187 | /* We won! No ARP replies, so just go back to monitor */ | |
188 | state = MONITOR; | |
189 | timeout_ms = -1; | |
190 | conflicts = 0; | |
191 | break; | |
192 | default: | |
193 | /* Invalid, should never happen. Restart the whole protocol */ | |
194 | state = PROBE; | |
195 | ip = pick(); | |
196 | timeout_ms = 0; | |
197 | nprobes = 0; | |
198 | nclaims = 0; | |
199 | break; | |
200 | } | |
201 | configure_wait(); | |
202 | } | |
203 | ||
204 | void link_local_receive_arp(struct arp_hdr *arp, int len) | |
205 | { | |
206 | int source_ip_conflict; | |
207 | int target_ip_conflict; | |
208 | ||
209 | if (state == DISABLED) | |
210 | return; | |
211 | ||
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"); | |
220 | timeout_ms = 0; | |
221 | } else { | |
222 | debug("adjusting timeout\n"); | |
223 | timeout_ms = diff | 1; /* never 0 */ | |
224 | } | |
225 | } | |
226 | /* | |
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()); | |
233 | if (ready) { | |
234 | run(argv, "deconfig", &ip); | |
235 | } | |
236 | return EXIT_FAILURE; | |
237 | } | |
238 | continue; | |
239 | } | |
240 | */ | |
241 | ||
242 | debug("%s recv arp type=%d, op=%d,\n", | |
243 | eth_get_name(), ntohs(arp->ar_pro), | |
244 | ntohs(arp->ar_op)); | |
245 | debug("\tsource=%pM %pI4\n", | |
246 | &arp->ar_sha, | |
247 | &arp->ar_spa); | |
248 | debug("\ttarget=%pM %pI4\n", | |
249 | &arp->ar_tha, | |
250 | &arp->ar_tpa); | |
251 | ||
252 | if (arp->ar_op != htons(ARPOP_REQUEST) | |
253 | && arp->ar_op != htons(ARPOP_REPLY) | |
254 | ) { | |
255 | configure_wait(); | |
256 | return; | |
257 | } | |
258 | ||
259 | source_ip_conflict = 0; | |
260 | target_ip_conflict = 0; | |
261 | ||
262 | if (memcmp(&arp->ar_spa, &ip, ARP_PLEN) == 0 | |
263 | && memcmp(&arp->ar_sha, NetOurEther, ARP_HLEN) != 0 | |
264 | ) { | |
265 | source_ip_conflict = 1; | |
266 | } | |
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 | |
270 | ) { | |
271 | target_ip_conflict = 1; | |
272 | } | |
273 | ||
274 | debug("state = %d, source ip conflict = %d, target ip conflict = %d\n", | |
275 | state, source_ip_conflict, target_ip_conflict); | |
276 | switch (state) { | |
277 | case PROBE: | |
278 | case ANNOUNCE: | |
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) { | |
282 | conflicts++; | |
283 | state = PROBE; | |
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; | |
288 | } | |
289 | ||
290 | /* restart the whole protocol */ | |
291 | ip = pick(); | |
292 | timeout_ms = 0; | |
293 | nprobes = 0; | |
294 | nclaims = 0; | |
295 | } | |
296 | break; | |
297 | case MONITOR: | |
298 | /* If a conflict, we try to defend with a single ARP probe */ | |
299 | if (source_ip_conflict) { | |
300 | debug("monitor conflict -- defending\n"); | |
301 | state = DEFEND; | |
302 | timeout_ms = DEFEND_INTERVAL * 1000; | |
303 | arp_raw_request(ip, NetOurEther, ip); | |
304 | } | |
305 | break; | |
306 | case DEFEND: | |
307 | /* Well, we tried. Start over (on conflict) */ | |
308 | if (source_ip_conflict) { | |
309 | state = PROBE; | |
310 | debug("defend conflict -- starting over\n"); | |
311 | ready = 0; | |
312 | NetOurIP = 0; | |
313 | ||
314 | /* restart the whole protocol */ | |
315 | ip = pick(); | |
316 | timeout_ms = 0; | |
317 | nprobes = 0; | |
318 | nclaims = 0; | |
319 | } | |
320 | break; | |
321 | default: | |
322 | /* Invalid, should never happen. Restart the whole protocol */ | |
323 | debug("invalid state -- starting over\n"); | |
324 | state = PROBE; | |
325 | ip = pick(); | |
326 | timeout_ms = 0; | |
327 | nprobes = 0; | |
328 | nclaims = 0; | |
329 | break; | |
330 | } | |
331 | configure_wait(); | |
332 | } |