Contents of /tags/mkinitrd-6_3_5/busybox/networking/ntpd_simple.c
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Sat Jan 29 14:06:54 2011 UTC (13 years, 8 months ago) by niro
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Sat Jan 29 14:06:54 2011 UTC (13 years, 8 months ago) by niro
File MIME type: text/plain
File size: 28965 byte(s)
tagged 'mkinitrd-6_3_5'
1 | /* |
2 | * NTP client/server, based on OpenNTPD 3.9p1 |
3 | * |
4 | * Author: Adam Tkac <vonsch@gmail.com> |
5 | * |
6 | * Licensed under GPLv2, see file LICENSE in this tarball for details. |
7 | */ |
8 | #include "libbb.h" |
9 | #include <netinet/ip.h> /* For IPTOS_LOWDELAY definition */ |
10 | #ifndef IPTOS_LOWDELAY |
11 | # define IPTOS_LOWDELAY 0x10 |
12 | #endif |
13 | #ifndef IP_PKTINFO |
14 | # error "Sorry, your kernel has to support IP_PKTINFO" |
15 | #endif |
16 | |
17 | |
18 | /* Sync to peers every N secs */ |
19 | #define INTERVAL_QUERY_NORMAL 30 |
20 | #define INTERVAL_QUERY_PATHETIC 60 |
21 | #define INTERVAL_QUERY_AGRESSIVE 5 |
22 | |
23 | /* Bad if *less than* TRUSTLEVEL_BADPEER */ |
24 | #define TRUSTLEVEL_BADPEER 6 |
25 | #define TRUSTLEVEL_PATHETIC 2 |
26 | #define TRUSTLEVEL_AGRESSIVE 8 |
27 | #define TRUSTLEVEL_MAX 10 |
28 | |
29 | #define QSCALE_OFF_MIN 0.05 |
30 | #define QSCALE_OFF_MAX 0.50 |
31 | |
32 | /* Single query might take N secs max */ |
33 | #define QUERYTIME_MAX 15 |
34 | /* Min offset for settime at start. "man ntpd" says it's 128 ms */ |
35 | #define STEPTIME_MIN_OFFSET 0.128 |
36 | |
37 | typedef struct { |
38 | uint32_t int_partl; |
39 | uint32_t fractionl; |
40 | } l_fixedpt_t; |
41 | |
42 | typedef struct { |
43 | uint16_t int_parts; |
44 | uint16_t fractions; |
45 | } s_fixedpt_t; |
46 | |
47 | enum { |
48 | NTP_DIGESTSIZE = 16, |
49 | NTP_MSGSIZE_NOAUTH = 48, |
50 | NTP_MSGSIZE = (NTP_MSGSIZE_NOAUTH + 4 + NTP_DIGESTSIZE), |
51 | }; |
52 | |
53 | typedef struct { |
54 | uint8_t m_status; /* status of local clock and leap info */ |
55 | uint8_t m_stratum; /* stratum level */ |
56 | uint8_t m_ppoll; /* poll value */ |
57 | int8_t m_precision_exp; |
58 | s_fixedpt_t m_rootdelay; |
59 | s_fixedpt_t m_dispersion; |
60 | uint32_t m_refid; |
61 | l_fixedpt_t m_reftime; |
62 | l_fixedpt_t m_orgtime; |
63 | l_fixedpt_t m_rectime; |
64 | l_fixedpt_t m_xmttime; |
65 | uint32_t m_keyid; |
66 | uint8_t m_digest[NTP_DIGESTSIZE]; |
67 | } msg_t; |
68 | |
69 | enum { |
70 | NTP_VERSION = 4, |
71 | NTP_MAXSTRATUM = 15, |
72 | |
73 | /* Status Masks */ |
74 | MODE_MASK = (7 << 0), |
75 | VERSION_MASK = (7 << 3), |
76 | VERSION_SHIFT = 3, |
77 | LI_MASK = (3 << 6), |
78 | |
79 | /* Leap Second Codes (high order two bits of m_status) */ |
80 | LI_NOWARNING = (0 << 6), /* no warning */ |
81 | LI_PLUSSEC = (1 << 6), /* add a second (61 seconds) */ |
82 | LI_MINUSSEC = (2 << 6), /* minus a second (59 seconds) */ |
83 | LI_ALARM = (3 << 6), /* alarm condition */ |
84 | |
85 | /* Mode values */ |
86 | MODE_RES0 = 0, /* reserved */ |
87 | MODE_SYM_ACT = 1, /* symmetric active */ |
88 | MODE_SYM_PAS = 2, /* symmetric passive */ |
89 | MODE_CLIENT = 3, /* client */ |
90 | MODE_SERVER = 4, /* server */ |
91 | MODE_BROADCAST = 5, /* broadcast */ |
92 | MODE_RES1 = 6, /* reserved for NTP control message */ |
93 | MODE_RES2 = 7, /* reserved for private use */ |
94 | }; |
95 | |
96 | #define OFFSET_1900_1970 2208988800UL /* 1970 - 1900 in seconds */ |
97 | |
98 | typedef struct { |
99 | double d_offset; |
100 | double d_delay; |
101 | //UNUSED: double d_error; |
102 | time_t d_rcv_time; |
103 | uint32_t d_refid4; |
104 | uint8_t d_leap; |
105 | uint8_t d_stratum; |
106 | uint8_t d_good; |
107 | } datapoint_t; |
108 | |
109 | #define NUM_DATAPOINTS 8 |
110 | typedef struct { |
111 | len_and_sockaddr *p_lsa; |
112 | char *p_dotted; |
113 | /* When to send new query (if p_fd == -1) |
114 | * or when receive times out (if p_fd >= 0): */ |
115 | time_t next_action_time; |
116 | int p_fd; |
117 | uint8_t p_datapoint_idx; |
118 | uint8_t p_trustlevel; |
119 | double p_xmttime; |
120 | datapoint_t update; |
121 | datapoint_t p_datapoint[NUM_DATAPOINTS]; |
122 | msg_t p_xmt_msg; |
123 | } peer_t; |
124 | |
125 | enum { |
126 | OPT_n = (1 << 0), |
127 | OPT_q = (1 << 1), |
128 | OPT_N = (1 << 2), |
129 | OPT_x = (1 << 3), |
130 | /* Insert new options above this line. */ |
131 | /* Non-compat options: */ |
132 | OPT_p = (1 << 4), |
133 | OPT_l = (1 << 5) * ENABLE_FEATURE_NTPD_SERVER, |
134 | }; |
135 | |
136 | |
137 | struct globals { |
138 | /* total round trip delay to currently selected reference clock */ |
139 | double rootdelay; |
140 | /* reference timestamp: time when the system clock was last set or corrected */ |
141 | double reftime; |
142 | llist_t *ntp_peers; |
143 | #if ENABLE_FEATURE_NTPD_SERVER |
144 | int listen_fd; |
145 | #endif |
146 | unsigned verbose; |
147 | unsigned peer_cnt; |
148 | unsigned scale; |
149 | uint32_t refid; |
150 | uint32_t refid4; |
151 | uint8_t synced; |
152 | uint8_t leap; |
153 | #define G_precision_exp -6 |
154 | // int8_t precision_exp; |
155 | uint8_t stratum; |
156 | uint8_t time_was_stepped; |
157 | uint8_t first_adj_done; |
158 | }; |
159 | #define G (*ptr_to_globals) |
160 | |
161 | static const int const_IPTOS_LOWDELAY = IPTOS_LOWDELAY; |
162 | |
163 | |
164 | static void |
165 | set_next(peer_t *p, unsigned t) |
166 | { |
167 | p->next_action_time = time(NULL) + t; |
168 | } |
169 | |
170 | static void |
171 | add_peers(char *s) |
172 | { |
173 | peer_t *p; |
174 | |
175 | p = xzalloc(sizeof(*p)); |
176 | p->p_lsa = xhost2sockaddr(s, 123); |
177 | p->p_dotted = xmalloc_sockaddr2dotted_noport(&p->p_lsa->u.sa); |
178 | p->p_fd = -1; |
179 | p->p_xmt_msg.m_status = MODE_CLIENT | (NTP_VERSION << 3); |
180 | p->p_trustlevel = TRUSTLEVEL_PATHETIC; |
181 | p->next_action_time = time(NULL); /* = set_next(p, 0); */ |
182 | |
183 | llist_add_to(&G.ntp_peers, p); |
184 | G.peer_cnt++; |
185 | } |
186 | |
187 | static double |
188 | gettime1900d(void) |
189 | { |
190 | struct timeval tv; |
191 | gettimeofday(&tv, NULL); /* never fails */ |
192 | return (tv.tv_sec + 1.0e-6 * tv.tv_usec + OFFSET_1900_1970); |
193 | } |
194 | |
195 | static void |
196 | d_to_tv(double d, struct timeval *tv) |
197 | { |
198 | tv->tv_sec = (long)d; |
199 | tv->tv_usec = (d - tv->tv_sec) * 1000000; |
200 | } |
201 | |
202 | static double |
203 | lfp_to_d(l_fixedpt_t lfp) |
204 | { |
205 | double ret; |
206 | lfp.int_partl = ntohl(lfp.int_partl); |
207 | lfp.fractionl = ntohl(lfp.fractionl); |
208 | ret = (double)lfp.int_partl + ((double)lfp.fractionl / UINT_MAX); |
209 | return ret; |
210 | } |
211 | |
212 | #if 0 //UNUSED |
213 | static double |
214 | sfp_to_d(s_fixedpt_t sfp) |
215 | { |
216 | double ret; |
217 | sfp.int_parts = ntohs(sfp.int_parts); |
218 | sfp.fractions = ntohs(sfp.fractions); |
219 | ret = (double)sfp.int_parts + ((double)sfp.fractions / USHRT_MAX); |
220 | return ret; |
221 | } |
222 | #endif |
223 | |
224 | #if ENABLE_FEATURE_NTPD_SERVER |
225 | static l_fixedpt_t |
226 | d_to_lfp(double d) |
227 | { |
228 | l_fixedpt_t lfp; |
229 | lfp.int_partl = (uint32_t)d; |
230 | lfp.fractionl = (uint32_t)((d - lfp.int_partl) * UINT_MAX); |
231 | lfp.int_partl = htonl(lfp.int_partl); |
232 | lfp.fractionl = htonl(lfp.fractionl); |
233 | return lfp; |
234 | } |
235 | |
236 | static s_fixedpt_t |
237 | d_to_sfp(double d) |
238 | { |
239 | s_fixedpt_t sfp; |
240 | sfp.int_parts = (uint16_t)d; |
241 | sfp.fractions = (uint16_t)((d - sfp.int_parts) * USHRT_MAX); |
242 | sfp.int_parts = htons(sfp.int_parts); |
243 | sfp.fractions = htons(sfp.fractions); |
244 | return sfp; |
245 | } |
246 | #endif |
247 | |
248 | static unsigned |
249 | error_interval(void) |
250 | { |
251 | unsigned interval, r; |
252 | interval = INTERVAL_QUERY_PATHETIC * QSCALE_OFF_MAX / QSCALE_OFF_MIN; |
253 | r = (unsigned)random() % (unsigned)(interval / 10); |
254 | return (interval + r); |
255 | } |
256 | |
257 | static int |
258 | do_sendto(int fd, |
259 | const struct sockaddr *from, const struct sockaddr *to, socklen_t addrlen, |
260 | msg_t *msg, ssize_t len) |
261 | { |
262 | ssize_t ret; |
263 | |
264 | errno = 0; |
265 | if (!from) { |
266 | ret = sendto(fd, msg, len, MSG_DONTWAIT, to, addrlen); |
267 | } else { |
268 | ret = send_to_from(fd, msg, len, MSG_DONTWAIT, to, from, addrlen); |
269 | } |
270 | if (ret != len) { |
271 | bb_perror_msg("send failed"); |
272 | return -1; |
273 | } |
274 | return 0; |
275 | } |
276 | |
277 | static int |
278 | send_query_to_peer(peer_t *p) |
279 | { |
280 | // Why do we need to bind()? |
281 | // See what happens when we don't bind: |
282 | // |
283 | // socket(PF_INET, SOCK_DGRAM, IPPROTO_IP) = 3 |
284 | // setsockopt(3, SOL_IP, IP_TOS, [16], 4) = 0 |
285 | // gettimeofday({1259071266, 327885}, NULL) = 0 |
286 | // sendto(3, "xxx", 48, MSG_DONTWAIT, {sa_family=AF_INET, sin_port=htons(123), sin_addr=inet_addr("10.34.32.125")}, 16) = 48 |
287 | // ^^^ we sent it from some source port picked by kernel. |
288 | // time(NULL) = 1259071266 |
289 | // write(2, "ntpd: entering poll 15 secs\n", 28) = 28 |
290 | // poll([{fd=3, events=POLLIN}], 1, 15000) = 1 ([{fd=3, revents=POLLIN}]) |
291 | // recv(3, "yyy", 68, MSG_DONTWAIT) = 48 |
292 | // ^^^ this recv will receive packets to any local port! |
293 | // |
294 | // Uncomment this and use strace to see it in action: |
295 | #define PROBE_LOCAL_ADDR // { len_and_sockaddr lsa; lsa.len = LSA_SIZEOF_SA; getsockname(p->query.fd, &lsa.u.sa, &lsa.len); } |
296 | |
297 | if (p->p_fd == -1) { |
298 | int fd, family; |
299 | len_and_sockaddr *local_lsa; |
300 | |
301 | family = p->p_lsa->u.sa.sa_family; |
302 | p->p_fd = fd = xsocket_type(&local_lsa, family, SOCK_DGRAM); |
303 | /* local_lsa has "null" address and port 0 now. |
304 | * bind() ensures we have a *particular port* selected by kernel |
305 | * and remembered in p->p_fd, thus later recv(p->p_fd) |
306 | * receives only packets sent to this port. |
307 | */ |
308 | PROBE_LOCAL_ADDR |
309 | xbind(fd, &local_lsa->u.sa, local_lsa->len); |
310 | PROBE_LOCAL_ADDR |
311 | #if ENABLE_FEATURE_IPV6 |
312 | if (family == AF_INET) |
313 | #endif |
314 | setsockopt(fd, IPPROTO_IP, IP_TOS, &const_IPTOS_LOWDELAY, sizeof(const_IPTOS_LOWDELAY)); |
315 | free(local_lsa); |
316 | } |
317 | |
318 | /* |
319 | * Send out a random 64-bit number as our transmit time. The NTP |
320 | * server will copy said number into the originate field on the |
321 | * response that it sends us. This is totally legal per the SNTP spec. |
322 | * |
323 | * The impact of this is two fold: we no longer send out the current |
324 | * system time for the world to see (which may aid an attacker), and |
325 | * it gives us a (not very secure) way of knowing that we're not |
326 | * getting spoofed by an attacker that can't capture our traffic |
327 | * but can spoof packets from the NTP server we're communicating with. |
328 | * |
329 | * Save the real transmit timestamp locally. |
330 | */ |
331 | p->p_xmt_msg.m_xmttime.int_partl = random(); |
332 | p->p_xmt_msg.m_xmttime.fractionl = random(); |
333 | p->p_xmttime = gettime1900d(); |
334 | |
335 | if (do_sendto(p->p_fd, /*from:*/ NULL, /*to:*/ &p->p_lsa->u.sa, /*addrlen:*/ p->p_lsa->len, |
336 | &p->p_xmt_msg, NTP_MSGSIZE_NOAUTH) == -1 |
337 | ) { |
338 | close(p->p_fd); |
339 | p->p_fd = -1; |
340 | set_next(p, INTERVAL_QUERY_PATHETIC); |
341 | return -1; |
342 | } |
343 | |
344 | if (G.verbose) |
345 | bb_error_msg("sent query to %s", p->p_dotted); |
346 | set_next(p, QUERYTIME_MAX); |
347 | |
348 | return 0; |
349 | } |
350 | |
351 | |
352 | /* Time is stepped only once, when the first packet from a peer is received. |
353 | */ |
354 | static void |
355 | step_time_once(double offset) |
356 | { |
357 | double dtime; |
358 | llist_t *item; |
359 | struct timeval tv; |
360 | char buf[80]; |
361 | time_t tval; |
362 | |
363 | if (G.time_was_stepped) |
364 | goto bail; |
365 | G.time_was_stepped = 1; |
366 | |
367 | /* if the offset is small, don't step, slew (later) */ |
368 | if (offset < STEPTIME_MIN_OFFSET && offset > -STEPTIME_MIN_OFFSET) |
369 | goto bail; |
370 | |
371 | gettimeofday(&tv, NULL); /* never fails */ |
372 | dtime = offset + tv.tv_sec; |
373 | dtime += 1.0e-6 * tv.tv_usec; |
374 | d_to_tv(dtime, &tv); |
375 | |
376 | if (settimeofday(&tv, NULL) == -1) |
377 | bb_perror_msg_and_die("settimeofday"); |
378 | |
379 | tval = tv.tv_sec; |
380 | strftime(buf, sizeof(buf), "%a %b %e %H:%M:%S %Z %Y", localtime(&tval)); |
381 | |
382 | bb_error_msg("setting clock to %s (offset %fs)", buf, offset); |
383 | |
384 | for (item = G.ntp_peers; item != NULL; item = item->link) { |
385 | peer_t *p = (peer_t *) item->data; |
386 | p->next_action_time -= (time_t)offset; |
387 | } |
388 | |
389 | bail: |
390 | if (option_mask32 & OPT_q) |
391 | exit(0); |
392 | } |
393 | |
394 | |
395 | /* Time is periodically slewed when we collect enough |
396 | * good data points. |
397 | */ |
398 | static int |
399 | compare_offsets(const void *aa, const void *bb) |
400 | { |
401 | const peer_t *const *a = aa; |
402 | const peer_t *const *b = bb; |
403 | if ((*a)->update.d_offset < (*b)->update.d_offset) |
404 | return -1; |
405 | return ((*a)->update.d_offset > (*b)->update.d_offset); |
406 | } |
407 | static unsigned |
408 | updated_scale(double offset) |
409 | { |
410 | if (offset < 0) |
411 | offset = -offset; |
412 | if (offset > QSCALE_OFF_MAX) |
413 | return 1; |
414 | if (offset < QSCALE_OFF_MIN) |
415 | return QSCALE_OFF_MAX / QSCALE_OFF_MIN; |
416 | return QSCALE_OFF_MAX / offset; |
417 | } |
418 | static void |
419 | slew_time(void) |
420 | { |
421 | llist_t *item; |
422 | double offset_median; |
423 | struct timeval tv; |
424 | |
425 | { |
426 | peer_t **peers = xzalloc(sizeof(peers[0]) * G.peer_cnt); |
427 | unsigned goodpeer_cnt = 0; |
428 | unsigned middle; |
429 | |
430 | for (item = G.ntp_peers; item != NULL; item = item->link) { |
431 | peer_t *p = (peer_t *) item->data; |
432 | if (p->p_trustlevel < TRUSTLEVEL_BADPEER) |
433 | continue; |
434 | if (!p->update.d_good) { |
435 | free(peers); |
436 | return; |
437 | } |
438 | peers[goodpeer_cnt++] = p; |
439 | } |
440 | |
441 | if (goodpeer_cnt == 0) { |
442 | free(peers); |
443 | goto clear_good; |
444 | } |
445 | |
446 | qsort(peers, goodpeer_cnt, sizeof(peers[0]), compare_offsets); |
447 | |
448 | middle = goodpeer_cnt / 2; |
449 | if (middle != 0 && (goodpeer_cnt & 1) == 0) { |
450 | offset_median = (peers[middle-1]->update.d_offset + peers[middle]->update.d_offset) / 2; |
451 | G.rootdelay = (peers[middle-1]->update.d_delay + peers[middle]->update.d_delay) / 2; |
452 | G.stratum = 1 + MAX(peers[middle-1]->update.d_stratum, peers[middle]->update.d_stratum); |
453 | } else { |
454 | offset_median = peers[middle]->update.d_offset; |
455 | G.rootdelay = peers[middle]->update.d_delay; |
456 | G.stratum = 1 + peers[middle]->update.d_stratum; |
457 | } |
458 | G.leap = peers[middle]->update.d_leap; |
459 | G.refid4 = peers[middle]->update.d_refid4; |
460 | G.refid = |
461 | #if ENABLE_FEATURE_IPV6 |
462 | peers[middle]->p_lsa->u.sa.sa_family != AF_INET ? |
463 | G.refid4 : |
464 | #endif |
465 | peers[middle]->p_lsa->u.sin.sin_addr.s_addr; |
466 | free(peers); |
467 | } |
468 | //TODO: if (offset_median > BIG) step_time(offset_median)? |
469 | |
470 | G.scale = updated_scale(offset_median); |
471 | |
472 | bb_error_msg("adjusting clock by %fs, our stratum is %u, time scale %u", |
473 | offset_median, G.stratum, G.scale); |
474 | |
475 | errno = 0; |
476 | d_to_tv(offset_median, &tv); |
477 | if (adjtime(&tv, &tv) == -1) |
478 | bb_perror_msg_and_die("adjtime failed"); |
479 | if (G.verbose >= 2) |
480 | bb_error_msg("old adjust: %d.%06u", (int)tv.tv_sec, (unsigned)tv.tv_usec); |
481 | |
482 | if (G.first_adj_done) { |
483 | uint8_t synced = (tv.tv_sec == 0 && tv.tv_usec == 0); |
484 | if (synced != G.synced) { |
485 | G.synced = synced; |
486 | bb_error_msg("clock is %ssynced", synced ? "" : "un"); |
487 | } |
488 | } |
489 | G.first_adj_done = 1; |
490 | |
491 | G.reftime = gettime1900d(); |
492 | |
493 | clear_good: |
494 | for (item = G.ntp_peers; item != NULL; item = item->link) { |
495 | peer_t *p = (peer_t *) item->data; |
496 | p->update.d_good = 0; |
497 | } |
498 | } |
499 | |
500 | static void |
501 | update_peer_data(peer_t *p) |
502 | { |
503 | /* Clock filter. |
504 | * Find the datapoint with the lowest delay. |
505 | * Use that as the peer update. |
506 | * Invalidate it and all older ones. |
507 | */ |
508 | int i; |
509 | int best = -1; |
510 | int good = 0; |
511 | |
512 | for (i = 0; i < NUM_DATAPOINTS; i++) { |
513 | if (p->p_datapoint[i].d_good) { |
514 | good++; |
515 | if (best < 0 || p->p_datapoint[i].d_delay < p->p_datapoint[best].d_delay) |
516 | best = i; |
517 | } |
518 | } |
519 | |
520 | if (good < 8) //FIXME: was it meant to be NUM_DATAPOINTS, not 8? |
521 | return; |
522 | |
523 | p->update = p->p_datapoint[best]; /* struct copy */ |
524 | slew_time(); |
525 | |
526 | for (i = 0; i < NUM_DATAPOINTS; i++) |
527 | if (p->p_datapoint[i].d_rcv_time <= p->p_datapoint[best].d_rcv_time) |
528 | p->p_datapoint[i].d_good = 0; |
529 | } |
530 | |
531 | static unsigned |
532 | scale_interval(unsigned requested) |
533 | { |
534 | unsigned interval, r; |
535 | interval = requested * G.scale; |
536 | r = (unsigned)random() % (unsigned)(MAX(5, interval / 10)); |
537 | return (interval + r); |
538 | } |
539 | static void |
540 | recv_and_process_peer_pkt(peer_t *p) |
541 | { |
542 | ssize_t size; |
543 | msg_t msg; |
544 | double T1, T2, T3, T4; |
545 | unsigned interval; |
546 | datapoint_t *datapoint; |
547 | |
548 | /* We can recvfrom here and check from.IP, but some multihomed |
549 | * ntp servers reply from their *other IP*. |
550 | * TODO: maybe we should check at least what we can: from.port == 123? |
551 | */ |
552 | size = recv(p->p_fd, &msg, sizeof(msg), MSG_DONTWAIT); |
553 | if (size == -1) { |
554 | bb_perror_msg("recv(%s) error", p->p_dotted); |
555 | if (errno == EHOSTUNREACH || errno == EHOSTDOWN |
556 | || errno == ENETUNREACH || errno == ENETDOWN |
557 | || errno == ECONNREFUSED || errno == EADDRNOTAVAIL |
558 | || errno == EAGAIN |
559 | ) { |
560 | //TODO: always do this? |
561 | set_next(p, error_interval()); |
562 | goto close_sock; |
563 | } |
564 | xfunc_die(); |
565 | } |
566 | |
567 | if (size != NTP_MSGSIZE_NOAUTH && size != NTP_MSGSIZE) { |
568 | bb_error_msg("malformed packet received from %s", p->p_dotted); |
569 | goto bail; |
570 | } |
571 | |
572 | if (msg.m_orgtime.int_partl != p->p_xmt_msg.m_xmttime.int_partl |
573 | || msg.m_orgtime.fractionl != p->p_xmt_msg.m_xmttime.fractionl |
574 | ) { |
575 | goto bail; |
576 | } |
577 | |
578 | if ((msg.m_status & LI_ALARM) == LI_ALARM |
579 | || msg.m_stratum == 0 |
580 | || msg.m_stratum > NTP_MAXSTRATUM |
581 | ) { |
582 | // TODO: stratum 0 responses may have commands in 32-bit m_refid field: |
583 | // "DENY", "RSTR" - peer does not like us at all |
584 | // "RATE" - peer is overloaded, reduce polling freq |
585 | interval = error_interval(); |
586 | bb_error_msg("reply from %s: not synced, next query in %us", p->p_dotted, interval); |
587 | goto close_sock; |
588 | } |
589 | |
590 | /* |
591 | * From RFC 2030 (with a correction to the delay math): |
592 | * |
593 | * Timestamp Name ID When Generated |
594 | * ------------------------------------------------------------ |
595 | * Originate Timestamp T1 time request sent by client |
596 | * Receive Timestamp T2 time request received by server |
597 | * Transmit Timestamp T3 time reply sent by server |
598 | * Destination Timestamp T4 time reply received by client |
599 | * |
600 | * The roundtrip delay and local clock offset are defined as |
601 | * |
602 | * delay = (T4 - T1) - (T3 - T2); offset = ((T2 - T1) + (T3 - T4)) / 2 |
603 | */ |
604 | T1 = p->p_xmttime; |
605 | T2 = lfp_to_d(msg.m_rectime); |
606 | T3 = lfp_to_d(msg.m_xmttime); |
607 | T4 = gettime1900d(); |
608 | |
609 | datapoint = &p->p_datapoint[p->p_datapoint_idx]; |
610 | |
611 | datapoint->d_offset = ((T2 - T1) + (T3 - T4)) / 2; |
612 | datapoint->d_delay = (T4 - T1) - (T3 - T2); |
613 | if (datapoint->d_delay < 0) { |
614 | bb_error_msg("reply from %s: negative delay %f", p->p_dotted, datapoint->d_delay); |
615 | interval = error_interval(); |
616 | set_next(p, interval); |
617 | goto close_sock; |
618 | } |
619 | //UNUSED: datapoint->d_error = (T2 - T1) - (T3 - T4); |
620 | datapoint->d_rcv_time = (time_t)(T4 - OFFSET_1900_1970); /* = time(NULL); */ |
621 | datapoint->d_good = 1; |
622 | |
623 | datapoint->d_leap = (msg.m_status & LI_MASK); |
624 | //UNUSED: datapoint->o_precision = msg.m_precision_exp; |
625 | //UNUSED: datapoint->o_rootdelay = sfp_to_d(msg.m_rootdelay); |
626 | //UNUSED: datapoint->o_rootdispersion = sfp_to_d(msg.m_dispersion); |
627 | //UNUSED: datapoint->d_refid = ntohl(msg.m_refid); |
628 | datapoint->d_refid4 = msg.m_xmttime.fractionl; |
629 | //UNUSED: datapoint->o_reftime = lfp_to_d(msg.m_reftime); |
630 | //UNUSED: datapoint->o_poll = msg.m_ppoll; |
631 | datapoint->d_stratum = msg.m_stratum; |
632 | |
633 | if (p->p_trustlevel < TRUSTLEVEL_PATHETIC) |
634 | interval = scale_interval(INTERVAL_QUERY_PATHETIC); |
635 | else if (p->p_trustlevel < TRUSTLEVEL_AGRESSIVE) |
636 | interval = scale_interval(INTERVAL_QUERY_AGRESSIVE); |
637 | else |
638 | interval = scale_interval(INTERVAL_QUERY_NORMAL); |
639 | |
640 | set_next(p, interval); |
641 | |
642 | /* Every received reply which we do not discard increases trust */ |
643 | if (p->p_trustlevel < TRUSTLEVEL_MAX) { |
644 | p->p_trustlevel++; |
645 | if (p->p_trustlevel == TRUSTLEVEL_BADPEER) |
646 | bb_error_msg("peer %s now valid", p->p_dotted); |
647 | } |
648 | |
649 | if (G.verbose) |
650 | bb_error_msg("reply from %s: offset %f delay %f, next query in %us", p->p_dotted, |
651 | datapoint->d_offset, datapoint->d_delay, interval); |
652 | |
653 | update_peer_data(p); |
654 | //TODO: do it after all peers had a chance to return at least one reply? |
655 | step_time_once(datapoint->d_offset); |
656 | |
657 | p->p_datapoint_idx++; |
658 | if (p->p_datapoint_idx >= NUM_DATAPOINTS) |
659 | p->p_datapoint_idx = 0; |
660 | |
661 | close_sock: |
662 | /* We do not expect any more packets from this peer for now. |
663 | * Closing the socket informs kernel about it. |
664 | * We open a new socket when we send a new query. |
665 | */ |
666 | close(p->p_fd); |
667 | p->p_fd = -1; |
668 | bail: |
669 | return; |
670 | } |
671 | |
672 | #if ENABLE_FEATURE_NTPD_SERVER |
673 | static void |
674 | recv_and_process_client_pkt(void /*int fd*/) |
675 | { |
676 | ssize_t size; |
677 | uint8_t version; |
678 | double rectime; |
679 | len_and_sockaddr *to; |
680 | struct sockaddr *from; |
681 | msg_t msg; |
682 | uint8_t query_status; |
683 | uint8_t query_ppoll; |
684 | l_fixedpt_t query_xmttime; |
685 | |
686 | to = get_sock_lsa(G.listen_fd); |
687 | from = xzalloc(to->len); |
688 | |
689 | size = recv_from_to(G.listen_fd, &msg, sizeof(msg), MSG_DONTWAIT, from, &to->u.sa, to->len); |
690 | if (size != NTP_MSGSIZE_NOAUTH && size != NTP_MSGSIZE) { |
691 | char *addr; |
692 | if (size < 0) { |
693 | if (errno == EAGAIN) |
694 | goto bail; |
695 | bb_perror_msg_and_die("recv"); |
696 | } |
697 | addr = xmalloc_sockaddr2dotted_noport(from); |
698 | bb_error_msg("malformed packet received from %s: size %u", addr, (int)size); |
699 | free(addr); |
700 | goto bail; |
701 | } |
702 | |
703 | query_status = msg.m_status; |
704 | query_ppoll = msg.m_ppoll; |
705 | query_xmttime = msg.m_xmttime; |
706 | |
707 | /* Build a reply packet */ |
708 | memset(&msg, 0, sizeof(msg)); |
709 | msg.m_status = G.synced ? G.leap : LI_ALARM; |
710 | msg.m_status |= (query_status & VERSION_MASK); |
711 | msg.m_status |= ((query_status & MODE_MASK) == MODE_CLIENT) ? |
712 | MODE_SERVER : MODE_SYM_PAS; |
713 | msg.m_stratum = G.stratum; |
714 | msg.m_ppoll = query_ppoll; |
715 | msg.m_precision_exp = G_precision_exp; |
716 | rectime = gettime1900d(); |
717 | msg.m_xmttime = msg.m_rectime = d_to_lfp(rectime); |
718 | msg.m_reftime = d_to_lfp(G.reftime); |
719 | //msg.m_xmttime = d_to_lfp(gettime1900d()); // = msg.m_rectime |
720 | msg.m_orgtime = query_xmttime; |
721 | msg.m_rootdelay = d_to_sfp(G.rootdelay); |
722 | version = (query_status & VERSION_MASK); /* ... >> VERSION_SHIFT - done below instead */ |
723 | msg.m_refid = (version > (3 << VERSION_SHIFT)) ? G.refid4 : G.refid; |
724 | |
725 | /* We reply from the local address packet was sent to, |
726 | * this makes to/from look swapped here: */ |
727 | do_sendto(G.listen_fd, |
728 | /*from:*/ &to->u.sa, /*to:*/ from, /*addrlen:*/ to->len, |
729 | &msg, size); |
730 | |
731 | bail: |
732 | free(to); |
733 | free(from); |
734 | } |
735 | #endif |
736 | |
737 | /* Upstream ntpd's options: |
738 | * |
739 | * -4 Force DNS resolution of host names to the IPv4 namespace. |
740 | * -6 Force DNS resolution of host names to the IPv6 namespace. |
741 | * -a Require cryptographic authentication for broadcast client, |
742 | * multicast client and symmetric passive associations. |
743 | * This is the default. |
744 | * -A Do not require cryptographic authentication for broadcast client, |
745 | * multicast client and symmetric passive associations. |
746 | * This is almost never a good idea. |
747 | * -b Enable the client to synchronize to broadcast servers. |
748 | * -c conffile |
749 | * Specify the name and path of the configuration file, |
750 | * default /etc/ntp.conf |
751 | * -d Specify debugging mode. This option may occur more than once, |
752 | * with each occurrence indicating greater detail of display. |
753 | * -D level |
754 | * Specify debugging level directly. |
755 | * -f driftfile |
756 | * Specify the name and path of the frequency file. |
757 | * This is the same operation as the "driftfile FILE" |
758 | * configuration command. |
759 | * -g Normally, ntpd exits with a message to the system log |
760 | * if the offset exceeds the panic threshold, which is 1000 s |
761 | * by default. This option allows the time to be set to any value |
762 | * without restriction; however, this can happen only once. |
763 | * If the threshold is exceeded after that, ntpd will exit |
764 | * with a message to the system log. This option can be used |
765 | * with the -q and -x options. See the tinker command for other options. |
766 | * -i jaildir |
767 | * Chroot the server to the directory jaildir. This option also implies |
768 | * that the server attempts to drop root privileges at startup |
769 | * (otherwise, chroot gives very little additional security). |
770 | * You may need to also specify a -u option. |
771 | * -k keyfile |
772 | * Specify the name and path of the symmetric key file, |
773 | * default /etc/ntp/keys. This is the same operation |
774 | * as the "keys FILE" configuration command. |
775 | * -l logfile |
776 | * Specify the name and path of the log file. The default |
777 | * is the system log file. This is the same operation as |
778 | * the "logfile FILE" configuration command. |
779 | * -L Do not listen to virtual IPs. The default is to listen. |
780 | * -n Don't fork. |
781 | * -N To the extent permitted by the operating system, |
782 | * run the ntpd at the highest priority. |
783 | * -p pidfile |
784 | * Specify the name and path of the file used to record the ntpd |
785 | * process ID. This is the same operation as the "pidfile FILE" |
786 | * configuration command. |
787 | * -P priority |
788 | * To the extent permitted by the operating system, |
789 | * run the ntpd at the specified priority. |
790 | * -q Exit the ntpd just after the first time the clock is set. |
791 | * This behavior mimics that of the ntpdate program, which is |
792 | * to be retired. The -g and -x options can be used with this option. |
793 | * Note: The kernel time discipline is disabled with this option. |
794 | * -r broadcastdelay |
795 | * Specify the default propagation delay from the broadcast/multicast |
796 | * server to this client. This is necessary only if the delay |
797 | * cannot be computed automatically by the protocol. |
798 | * -s statsdir |
799 | * Specify the directory path for files created by the statistics |
800 | * facility. This is the same operation as the "statsdir DIR" |
801 | * configuration command. |
802 | * -t key |
803 | * Add a key number to the trusted key list. This option can occur |
804 | * more than once. |
805 | * -u user[:group] |
806 | * Specify a user, and optionally a group, to switch to. |
807 | * -v variable |
808 | * -V variable |
809 | * Add a system variable listed by default. |
810 | * -x Normally, the time is slewed if the offset is less than the step |
811 | * threshold, which is 128 ms by default, and stepped if above |
812 | * the threshold. This option sets the threshold to 600 s, which is |
813 | * well within the accuracy window to set the clock manually. |
814 | * Note: since the slew rate of typical Unix kernels is limited |
815 | * to 0.5 ms/s, each second of adjustment requires an amortization |
816 | * interval of 2000 s. Thus, an adjustment as much as 600 s |
817 | * will take almost 14 days to complete. This option can be used |
818 | * with the -g and -q options. See the tinker command for other options. |
819 | * Note: The kernel time discipline is disabled with this option. |
820 | */ |
821 | |
822 | /* By doing init in a separate function we decrease stack usage |
823 | * in main loop. |
824 | */ |
825 | static NOINLINE void ntp_init(char **argv) |
826 | { |
827 | unsigned opts; |
828 | llist_t *peers; |
829 | |
830 | srandom(getpid()); |
831 | |
832 | if (getuid()) |
833 | bb_error_msg_and_die(bb_msg_you_must_be_root); |
834 | |
835 | peers = NULL; |
836 | opt_complementary = "dd:p::"; /* d: counter, p: list */ |
837 | opts = getopt32(argv, |
838 | "nqNx" /* compat */ |
839 | "p:"IF_FEATURE_NTPD_SERVER("l") /* NOT compat */ |
840 | "d" /* compat */ |
841 | "46aAbgL", /* compat, ignored */ |
842 | &peers, &G.verbose); |
843 | if (!(opts & (OPT_p|OPT_l))) |
844 | bb_show_usage(); |
845 | if (opts & OPT_x) /* disable stepping, only slew is allowed */ |
846 | G.time_was_stepped = 1; |
847 | while (peers) |
848 | add_peers(llist_pop(&peers)); |
849 | if (!(opts & OPT_n)) { |
850 | bb_daemonize_or_rexec(DAEMON_DEVNULL_STDIO, argv); |
851 | logmode = LOGMODE_NONE; |
852 | } |
853 | #if ENABLE_FEATURE_NTPD_SERVER |
854 | G.listen_fd = -1; |
855 | if (opts & OPT_l) { |
856 | G.listen_fd = create_and_bind_dgram_or_die(NULL, 123); |
857 | socket_want_pktinfo(G.listen_fd); |
858 | setsockopt(G.listen_fd, IPPROTO_IP, IP_TOS, &const_IPTOS_LOWDELAY, sizeof(const_IPTOS_LOWDELAY)); |
859 | } |
860 | #endif |
861 | /* I hesitate to set -20 prio. -15 should be high enough for timekeeping */ |
862 | if (opts & OPT_N) |
863 | setpriority(PRIO_PROCESS, 0, -15); |
864 | |
865 | /* Set some globals */ |
866 | #if 0 |
867 | /* With constant b = 100, G.precision_exp is also constant -6. |
868 | * Uncomment this and you'll see */ |
869 | { |
870 | int prec = 0; |
871 | int b; |
872 | # if 0 |
873 | struct timespec tp; |
874 | /* We can use sys_clock_getres but assuming 10ms tick should be fine */ |
875 | clock_getres(CLOCK_REALTIME, &tp); |
876 | tp.tv_sec = 0; |
877 | tp.tv_nsec = 10000000; |
878 | b = 1000000000 / tp.tv_nsec; /* convert to Hz */ |
879 | # else |
880 | b = 100; /* b = 1000000000/10000000 = 100 */ |
881 | # endif |
882 | while (b > 1) |
883 | prec--, b >>= 1; |
884 | //G.precision_exp = prec; |
885 | bb_error_msg("G.precision_exp:%d", prec); /* -6 */ |
886 | } |
887 | #endif |
888 | G.scale = 1; |
889 | |
890 | bb_signals((1 << SIGTERM) | (1 << SIGINT), record_signo); |
891 | bb_signals((1 << SIGPIPE) | (1 << SIGHUP), SIG_IGN); |
892 | } |
893 | |
894 | int ntpd_main(int argc UNUSED_PARAM, char **argv) MAIN_EXTERNALLY_VISIBLE; |
895 | int ntpd_main(int argc UNUSED_PARAM, char **argv) |
896 | { |
897 | struct globals g; |
898 | struct pollfd *pfd; |
899 | peer_t **idx2peer; |
900 | |
901 | memset(&g, 0, sizeof(g)); |
902 | SET_PTR_TO_GLOBALS(&g); |
903 | |
904 | ntp_init(argv); |
905 | |
906 | { |
907 | /* if ENABLE_FEATURE_NTPD_SERVER, + 1 for listen_fd: */ |
908 | unsigned cnt = g.peer_cnt + ENABLE_FEATURE_NTPD_SERVER; |
909 | idx2peer = xzalloc(sizeof(idx2peer[0]) * cnt); |
910 | pfd = xzalloc(sizeof(pfd[0]) * cnt); |
911 | } |
912 | |
913 | while (!bb_got_signal) { |
914 | llist_t *item; |
915 | unsigned i, j; |
916 | unsigned sent_cnt, trial_cnt; |
917 | int nfds, timeout; |
918 | time_t cur_time, nextaction; |
919 | |
920 | /* Nothing between here and poll() blocks for any significant time */ |
921 | |
922 | cur_time = time(NULL); |
923 | nextaction = cur_time + 3600; |
924 | |
925 | i = 0; |
926 | #if ENABLE_FEATURE_NTPD_SERVER |
927 | if (g.listen_fd != -1) { |
928 | pfd[0].fd = g.listen_fd; |
929 | pfd[0].events = POLLIN; |
930 | i++; |
931 | } |
932 | #endif |
933 | /* Pass over peer list, send requests, time out on receives */ |
934 | sent_cnt = trial_cnt = 0; |
935 | for (item = g.ntp_peers; item != NULL; item = item->link) { |
936 | peer_t *p = (peer_t *) item->data; |
937 | |
938 | /* Overflow-safe "if (p->next_action_time <= cur_time) ..." */ |
939 | if ((int)(cur_time - p->next_action_time) >= 0) { |
940 | if (p->p_fd == -1) { |
941 | /* Time to send new req */ |
942 | trial_cnt++; |
943 | if (send_query_to_peer(p) == 0) |
944 | sent_cnt++; |
945 | } else { |
946 | /* Timed out waiting for reply */ |
947 | close(p->p_fd); |
948 | p->p_fd = -1; |
949 | timeout = error_interval(); |
950 | bb_error_msg("timed out waiting for %s, " |
951 | "next query in %us", p->p_dotted, timeout); |
952 | if (p->p_trustlevel >= TRUSTLEVEL_BADPEER) { |
953 | p->p_trustlevel /= 2; |
954 | if (p->p_trustlevel < TRUSTLEVEL_BADPEER) |
955 | bb_error_msg("peer %s now invalid", p->p_dotted); |
956 | } |
957 | set_next(p, timeout); |
958 | } |
959 | } |
960 | |
961 | if (p->next_action_time < nextaction) |
962 | nextaction = p->next_action_time; |
963 | |
964 | if (p->p_fd >= 0) { |
965 | /* Wait for reply from this peer */ |
966 | pfd[i].fd = p->p_fd; |
967 | pfd[i].events = POLLIN; |
968 | idx2peer[i] = p; |
969 | i++; |
970 | } |
971 | } |
972 | |
973 | if ((trial_cnt > 0 && sent_cnt == 0) || g.peer_cnt == 0) |
974 | step_time_once(0); /* no good peers, don't wait */ |
975 | |
976 | timeout = nextaction - cur_time; |
977 | if (timeout < 1) |
978 | timeout = 1; |
979 | |
980 | /* Here we may block */ |
981 | if (g.verbose >= 2) |
982 | bb_error_msg("poll %us, sockets:%u", timeout, i); |
983 | nfds = poll(pfd, i, timeout * 1000); |
984 | if (nfds <= 0) |
985 | continue; |
986 | |
987 | /* Process any received packets */ |
988 | j = 0; |
989 | #if ENABLE_FEATURE_NTPD_SERVER |
990 | if (g.listen_fd != -1) { |
991 | if (pfd[0].revents /* & (POLLIN|POLLERR)*/) { |
992 | nfds--; |
993 | recv_and_process_client_pkt(/*g.listen_fd*/); |
994 | } |
995 | j = 1; |
996 | } |
997 | #endif |
998 | for (; nfds != 0 && j < i; j++) { |
999 | if (pfd[j].revents /* & (POLLIN|POLLERR)*/) { |
1000 | nfds--; |
1001 | recv_and_process_peer_pkt(idx2peer[j]); |
1002 | } |
1003 | } |
1004 | } /* while (!bb_got_signal) */ |
1005 | |
1006 | kill_myself_with_sig(bb_got_signal); |
1007 | } |