source: branches/3.2/mindi-busybox/networking/ntpd_simple.c @ 3232

Last change on this file since 3232 was 3232, checked in by bruno, 6 years ago
  • Update mindi-busybox to 1.21.1
  • Property svn:eol-style set to native
File size: 28.3 KB
Line 
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 source tree.
7 */
8#include "libbb.h"
9#include <netinet/ip.h> /* For IPTOS_LOWDELAY definition */
10#include <sys/resource.h> /* setpriority */
11#ifndef IPTOS_LOWDELAY
12# define IPTOS_LOWDELAY 0x10
13#endif
14#ifndef IP_PKTINFO
15# error "Sorry, your kernel has to support IP_PKTINFO"
16#endif
17
18
19/* Sync to peers every N secs */
20#define INTERVAL_QUERY_NORMAL    30
21#define INTERVAL_QUERY_PATHETIC  60
22#define INTERVAL_QUERY_AGRESSIVE  5
23
24/* Bad if *less than* TRUSTLEVEL_BADPEER */
25#define TRUSTLEVEL_BADPEER        6
26#define TRUSTLEVEL_PATHETIC       2
27#define TRUSTLEVEL_AGRESSIVE      8
28#define TRUSTLEVEL_MAX           10
29
30#define QSCALE_OFF_MIN         0.05
31#define QSCALE_OFF_MAX         0.50
32
33/* Single query might take N secs max */
34#define QUERYTIME_MAX            15
35/* Min offset for settime at start. "man ntpd" says it's 128 ms */
36#define STEPTIME_MIN_OFFSET   0.128
37
38typedef struct {
39    uint32_t int_partl;
40    uint32_t fractionl;
41} l_fixedpt_t;
42
43typedef struct {
44    uint16_t int_parts;
45    uint16_t fractions;
46} s_fixedpt_t;
47
48enum {
49    NTP_DIGESTSIZE     = 16,
50    NTP_MSGSIZE_NOAUTH = 48,
51    NTP_MSGSIZE        = (NTP_MSGSIZE_NOAUTH + 4 + NTP_DIGESTSIZE),
52};
53
54typedef struct {
55    uint8_t     m_status;     /* status of local clock and leap info */
56    uint8_t     m_stratum;    /* stratum level */
57    uint8_t     m_ppoll;      /* poll value */
58    int8_t      m_precision_exp;
59    s_fixedpt_t m_rootdelay;
60    s_fixedpt_t m_dispersion;
61    uint32_t    m_refid;
62    l_fixedpt_t m_reftime;
63    l_fixedpt_t m_orgtime;
64    l_fixedpt_t m_rectime;
65    l_fixedpt_t m_xmttime;
66    uint32_t    m_keyid;
67    uint8_t     m_digest[NTP_DIGESTSIZE];
68} msg_t;
69
70enum {
71    NTP_VERSION     = 4,
72    NTP_MAXSTRATUM  = 15,
73
74    /* Status Masks */
75    MODE_MASK       = (7 << 0),
76    VERSION_MASK    = (7 << 3),
77    VERSION_SHIFT   = 3,
78    LI_MASK         = (3 << 6),
79
80    /* Leap Second Codes (high order two bits of m_status) */
81    LI_NOWARNING    = (0 << 6),    /* no warning */
82    LI_PLUSSEC      = (1 << 6),    /* add a second (61 seconds) */
83    LI_MINUSSEC     = (2 << 6),    /* minus a second (59 seconds) */
84    LI_ALARM        = (3 << 6),    /* alarm condition */
85
86    /* Mode values */
87    MODE_RES0       = 0,    /* reserved */
88    MODE_SYM_ACT    = 1,    /* symmetric active */
89    MODE_SYM_PAS    = 2,    /* symmetric passive */
90    MODE_CLIENT     = 3,    /* client */
91    MODE_SERVER     = 4,    /* server */
92    MODE_BROADCAST  = 5,    /* broadcast */
93    MODE_RES1       = 6,    /* reserved for NTP control message */
94    MODE_RES2       = 7,    /* reserved for private use */
95};
96
97#define OFFSET_1900_1970 2208988800UL  /* 1970 - 1900 in seconds */
98
99typedef struct {
100    double   d_offset;
101    double   d_delay;
102    //UNUSED: double d_error;
103    time_t   d_rcv_time;
104    uint32_t d_refid4;
105    uint8_t  d_leap;
106    uint8_t  d_stratum;
107    uint8_t  d_good;
108} datapoint_t;
109
110#define NUM_DATAPOINTS  8
111typedef struct {
112    len_and_sockaddr *p_lsa;
113    char             *p_dotted;
114    /* When to send new query (if p_fd == -1)
115     * or when receive times out (if p_fd >= 0): */
116    time_t           next_action_time;
117    int              p_fd;
118    uint8_t          p_datapoint_idx;
119    uint8_t          p_trustlevel;
120    double           p_xmttime;
121    datapoint_t      update;
122    datapoint_t      p_datapoint[NUM_DATAPOINTS];
123    msg_t            p_xmt_msg;
124} peer_t;
125
126enum {
127    OPT_n = (1 << 0),
128    OPT_q = (1 << 1),
129    OPT_N = (1 << 2),
130    OPT_x = (1 << 3),
131    /* Insert new options above this line. */
132    /* Non-compat options: */
133    OPT_p = (1 << 4),
134    OPT_l = (1 << 5) * ENABLE_FEATURE_NTPD_SERVER,
135};
136
137
138struct globals {
139    /* total round trip delay to currently selected reference clock */
140    double   rootdelay;
141    /* reference timestamp: time when the system clock was last set or corrected */
142    double   reftime;
143    llist_t  *ntp_peers;
144#if ENABLE_FEATURE_NTPD_SERVER
145    int      listen_fd;
146#endif
147    unsigned verbose;
148    unsigned peer_cnt;
149    unsigned scale;
150    uint32_t refid;
151    uint32_t refid4;
152    uint8_t  synced;
153    uint8_t  leap;
154#define G_precision_exp -6
155//  int8_t   precision_exp;
156    uint8_t  stratum;
157    uint8_t  time_was_stepped;
158    uint8_t  first_adj_done;
159};
160#define G (*ptr_to_globals)
161
162static const int const_IPTOS_LOWDELAY = IPTOS_LOWDELAY;
163
164
165static void
166set_next(peer_t *p, unsigned t)
167{
168    p->next_action_time = time(NULL) + t;
169}
170
171static void
172add_peers(char *s)
173{
174    peer_t *p;
175
176    p = xzalloc(sizeof(*p));
177    p->p_lsa = xhost2sockaddr(s, 123);
178    p->p_dotted = xmalloc_sockaddr2dotted_noport(&p->p_lsa->u.sa);
179    p->p_fd = -1;
180    p->p_xmt_msg.m_status = MODE_CLIENT | (NTP_VERSION << 3);
181    p->p_trustlevel = TRUSTLEVEL_PATHETIC;
182    p->next_action_time = time(NULL); /* = set_next(p, 0); */
183
184    llist_add_to(&G.ntp_peers, p);
185    G.peer_cnt++;
186}
187
188static double
189gettime1900d(void)
190{
191    struct timeval tv;
192    gettimeofday(&tv, NULL); /* never fails */
193    return (tv.tv_sec + 1.0e-6 * tv.tv_usec + OFFSET_1900_1970);
194}
195
196static void
197d_to_tv(double d, struct timeval *tv)
198{
199    tv->tv_sec = (long)d;
200    tv->tv_usec = (d - tv->tv_sec) * 1000000;
201}
202
203static double
204lfp_to_d(l_fixedpt_t lfp)
205{
206    double ret;
207    lfp.int_partl = ntohl(lfp.int_partl);
208    lfp.fractionl = ntohl(lfp.fractionl);
209    ret = (double)lfp.int_partl + ((double)lfp.fractionl / UINT_MAX);
210    return ret;
211}
212
213#if 0 //UNUSED
214static double
215sfp_to_d(s_fixedpt_t sfp)
216{
217    double ret;
218    sfp.int_parts = ntohs(sfp.int_parts);
219    sfp.fractions = ntohs(sfp.fractions);
220    ret = (double)sfp.int_parts + ((double)sfp.fractions / USHRT_MAX);
221    return ret;
222}
223#endif
224
225#if ENABLE_FEATURE_NTPD_SERVER
226static l_fixedpt_t
227d_to_lfp(double d)
228{
229    l_fixedpt_t lfp;
230    lfp.int_partl = (uint32_t)d;
231    lfp.fractionl = (uint32_t)((d - lfp.int_partl) * UINT_MAX);
232    lfp.int_partl = htonl(lfp.int_partl);
233    lfp.fractionl = htonl(lfp.fractionl);
234    return lfp;
235}
236
237static s_fixedpt_t
238d_to_sfp(double d)
239{
240    s_fixedpt_t sfp;
241    sfp.int_parts = (uint16_t)d;
242    sfp.fractions = (uint16_t)((d - sfp.int_parts) * USHRT_MAX);
243    sfp.int_parts = htons(sfp.int_parts);
244    sfp.fractions = htons(sfp.fractions);
245    return sfp;
246}
247#endif
248
249static unsigned
250error_interval(void)
251{
252    unsigned interval, r;
253    interval = INTERVAL_QUERY_PATHETIC * QSCALE_OFF_MAX / QSCALE_OFF_MIN;
254    r = (unsigned)random() % (unsigned)(interval / 10);
255    return (interval + r);
256}
257
258static int
259do_sendto(int fd,
260        const struct sockaddr *from, const struct sockaddr *to, socklen_t addrlen,
261        msg_t *msg, ssize_t len)
262{
263    ssize_t ret;
264
265    errno = 0;
266    if (!from) {
267        ret = sendto(fd, msg, len, MSG_DONTWAIT, to, addrlen);
268    } else {
269        ret = send_to_from(fd, msg, len, MSG_DONTWAIT, to, from, addrlen);
270    }
271    if (ret != len) {
272        bb_perror_msg("send failed");
273        return -1;
274    }
275    return 0;
276}
277
278static int
279send_query_to_peer(peer_t *p)
280{
281    // Why do we need to bind()?
282    // See what happens when we don't bind:
283    //
284    // socket(PF_INET, SOCK_DGRAM, IPPROTO_IP) = 3
285    // setsockopt(3, SOL_IP, IP_TOS, [16], 4) = 0
286    // gettimeofday({1259071266, 327885}, NULL) = 0
287    // sendto(3, "xxx", 48, MSG_DONTWAIT, {sa_family=AF_INET, sin_port=htons(123), sin_addr=inet_addr("10.34.32.125")}, 16) = 48
288    // ^^^ we sent it from some source port picked by kernel.
289    // time(NULL)              = 1259071266
290    // write(2, "ntpd: entering poll 15 secs\n", 28) = 28
291    // poll([{fd=3, events=POLLIN}], 1, 15000) = 1 ([{fd=3, revents=POLLIN}])
292    // recv(3, "yyy", 68, MSG_DONTWAIT) = 48
293    // ^^^ this recv will receive packets to any local port!
294    //
295    // Uncomment this and use strace to see it in action:
296#define PROBE_LOCAL_ADDR // { len_and_sockaddr lsa; lsa.len = LSA_SIZEOF_SA; getsockname(p->query.fd, &lsa.u.sa, &lsa.len); }
297
298    if (p->p_fd == -1) {
299        int fd, family;
300        len_and_sockaddr *local_lsa;
301
302        family = p->p_lsa->u.sa.sa_family;
303        p->p_fd = fd = xsocket_type(&local_lsa, family, SOCK_DGRAM);
304        /* local_lsa has "null" address and port 0 now.
305         * bind() ensures we have a *particular port* selected by kernel
306         * and remembered in p->p_fd, thus later recv(p->p_fd)
307         * receives only packets sent to this port.
308         */
309        PROBE_LOCAL_ADDR
310        xbind(fd, &local_lsa->u.sa, local_lsa->len);
311        PROBE_LOCAL_ADDR
312#if ENABLE_FEATURE_IPV6
313        if (family == AF_INET)
314#endif
315            setsockopt(fd, IPPROTO_IP, IP_TOS, &const_IPTOS_LOWDELAY, sizeof(const_IPTOS_LOWDELAY));
316        free(local_lsa);
317    }
318
319    /*
320     * Send out a random 64-bit number as our transmit time.  The NTP
321     * server will copy said number into the originate field on the
322     * response that it sends us.  This is totally legal per the SNTP spec.
323     *
324     * The impact of this is two fold: we no longer send out the current
325     * system time for the world to see (which may aid an attacker), and
326     * it gives us a (not very secure) way of knowing that we're not
327     * getting spoofed by an attacker that can't capture our traffic
328     * but can spoof packets from the NTP server we're communicating with.
329     *
330     * Save the real transmit timestamp locally.
331     */
332    p->p_xmt_msg.m_xmttime.int_partl = random();
333    p->p_xmt_msg.m_xmttime.fractionl = random();
334    p->p_xmttime = gettime1900d();
335
336    if (do_sendto(p->p_fd, /*from:*/ NULL, /*to:*/ &p->p_lsa->u.sa, /*addrlen:*/ p->p_lsa->len,
337            &p->p_xmt_msg, NTP_MSGSIZE_NOAUTH) == -1
338    ) {
339        close(p->p_fd);
340        p->p_fd = -1;
341        set_next(p, INTERVAL_QUERY_PATHETIC);
342        return -1;
343    }
344
345    if (G.verbose)
346        bb_error_msg("sent query to %s", p->p_dotted);
347    set_next(p, QUERYTIME_MAX);
348
349    return 0;
350}
351
352
353/* Time is stepped only once, when the first packet from a peer is received.
354 */
355static void
356step_time_once(double offset)
357{
358    double dtime;
359    llist_t *item;
360    struct timeval tv;
361    char buf[80];
362    time_t tval;
363
364    if (G.time_was_stepped)
365        goto bail;
366    G.time_was_stepped = 1;
367
368    /* if the offset is small, don't step, slew (later) */
369    if (offset < STEPTIME_MIN_OFFSET && offset > -STEPTIME_MIN_OFFSET)
370        goto bail;
371
372    gettimeofday(&tv, NULL); /* never fails */
373    dtime = offset + tv.tv_sec;
374    dtime += 1.0e-6 * tv.tv_usec;
375    d_to_tv(dtime, &tv);
376
377    if (settimeofday(&tv, NULL) == -1)
378        bb_perror_msg_and_die("settimeofday");
379
380    tval = tv.tv_sec;
381    strftime(buf, sizeof(buf), "%a %b %e %H:%M:%S %Z %Y", localtime(&tval));
382
383    bb_error_msg("setting clock to %s (offset %fs)", buf, offset);
384
385    for (item = G.ntp_peers; item != NULL; item = item->link) {
386        peer_t *p = (peer_t *) item->data;
387        p->next_action_time -= (time_t)offset;
388    }
389
390 bail:
391    if (option_mask32 & OPT_q)
392        exit(0);
393}
394
395
396/* Time is periodically slewed when we collect enough
397 * good data points.
398 */
399static int
400compare_offsets(const void *aa, const void *bb)
401{
402    const peer_t *const *a = aa;
403    const peer_t *const *b = bb;
404    if ((*a)->update.d_offset < (*b)->update.d_offset)
405        return -1;
406    return ((*a)->update.d_offset > (*b)->update.d_offset);
407}
408static unsigned
409updated_scale(double offset)
410{
411    if (offset < 0)
412        offset = -offset;
413    if (offset > QSCALE_OFF_MAX)
414        return 1;
415    if (offset < QSCALE_OFF_MIN)
416        return QSCALE_OFF_MAX / QSCALE_OFF_MIN;
417    return QSCALE_OFF_MAX / offset;
418}
419static void
420slew_time(void)
421{
422    llist_t *item;
423    double offset_median;
424    struct timeval tv;
425
426    {
427        peer_t **peers = xzalloc(sizeof(peers[0]) * G.peer_cnt);
428        unsigned goodpeer_cnt = 0;
429        unsigned middle;
430
431        for (item = G.ntp_peers; item != NULL; item = item->link) {
432            peer_t *p = (peer_t *) item->data;
433            if (p->p_trustlevel < TRUSTLEVEL_BADPEER)
434                continue;
435            if (!p->update.d_good) {
436                free(peers);
437                return;
438            }
439            peers[goodpeer_cnt++] = p;
440        }
441
442        if (goodpeer_cnt == 0) {
443            free(peers);
444            goto clear_good;
445        }
446
447        qsort(peers, goodpeer_cnt, sizeof(peers[0]), compare_offsets);
448
449        middle = goodpeer_cnt / 2;
450        if (middle != 0 && (goodpeer_cnt & 1) == 0) {
451            offset_median = (peers[middle-1]->update.d_offset + peers[middle]->update.d_offset) / 2;
452            G.rootdelay = (peers[middle-1]->update.d_delay + peers[middle]->update.d_delay) / 2;
453            G.stratum = 1 + MAX(peers[middle-1]->update.d_stratum, peers[middle]->update.d_stratum);
454        } else {
455            offset_median = peers[middle]->update.d_offset;
456            G.rootdelay = peers[middle]->update.d_delay;
457            G.stratum = 1 + peers[middle]->update.d_stratum;
458        }
459        G.leap = peers[middle]->update.d_leap;
460        G.refid4 = peers[middle]->update.d_refid4;
461        G.refid =
462#if ENABLE_FEATURE_IPV6
463            peers[middle]->p_lsa->u.sa.sa_family != AF_INET ?
464                G.refid4 :
465#endif
466                peers[middle]->p_lsa->u.sin.sin_addr.s_addr;
467        free(peers);
468    }
469//TODO: if (offset_median > BIG) step_time(offset_median)?
470
471    G.scale = updated_scale(offset_median);
472
473    bb_error_msg("adjusting clock by %fs, our stratum is %u, time scale %u",
474            offset_median, G.stratum, G.scale);
475
476    errno = 0;
477    d_to_tv(offset_median, &tv);
478    if (adjtime(&tv, &tv) == -1)
479        bb_perror_msg_and_die("adjtime failed");
480    if (G.verbose >= 2)
481        bb_error_msg("old adjust: %d.%06u", (int)tv.tv_sec, (unsigned)tv.tv_usec);
482
483    if (G.first_adj_done) {
484        uint8_t synced = (tv.tv_sec == 0 && tv.tv_usec == 0);
485        if (synced != G.synced) {
486            G.synced = synced;
487            bb_error_msg("clock is %ssynced", synced ? "" : "un");
488        }
489    }
490    G.first_adj_done = 1;
491
492    G.reftime = gettime1900d();
493
494 clear_good:
495    for (item = G.ntp_peers; item != NULL; item = item->link) {
496        peer_t *p = (peer_t *) item->data;
497        p->update.d_good = 0;
498    }
499}
500
501static void
502update_peer_data(peer_t *p)
503{
504    /* Clock filter.
505     * Find the datapoint with the lowest delay.
506     * Use that as the peer update.
507     * Invalidate it and all older ones.
508     */
509    int i;
510    int best = -1;
511    int good = 0;
512
513    for (i = 0; i < NUM_DATAPOINTS; i++) {
514        if (p->p_datapoint[i].d_good) {
515            good++;
516            if (best < 0 || p->p_datapoint[i].d_delay < p->p_datapoint[best].d_delay)
517                best = i;
518        }
519    }
520
521    if (good < 8) //FIXME: was it meant to be NUM_DATAPOINTS, not 8?
522        return;
523
524    p->update = p->p_datapoint[best]; /* struct copy */
525    slew_time();
526
527    for (i = 0; i < NUM_DATAPOINTS; i++)
528        if (p->p_datapoint[i].d_rcv_time <= p->p_datapoint[best].d_rcv_time)
529            p->p_datapoint[i].d_good = 0;
530}
531
532static unsigned
533scale_interval(unsigned requested)
534{
535    unsigned interval, r;
536    interval = requested * G.scale;
537    r = (unsigned)random() % (unsigned)(MAX(5, interval / 10));
538    return (interval + r);
539}
540static void
541recv_and_process_peer_pkt(peer_t *p)
542{
543    ssize_t     size;
544    msg_t       msg;
545    double      T1, T2, T3, T4;
546    unsigned    interval;
547    datapoint_t *datapoint;
548
549    /* We can recvfrom here and check from.IP, but some multihomed
550     * ntp servers reply from their *other IP*.
551     * TODO: maybe we should check at least what we can: from.port == 123?
552     */
553    size = recv(p->p_fd, &msg, sizeof(msg), MSG_DONTWAIT);
554    if (size == -1) {
555        bb_perror_msg("recv(%s) error", p->p_dotted);
556        if (errno == EHOSTUNREACH || errno == EHOSTDOWN
557         || errno == ENETUNREACH || errno == ENETDOWN
558         || errno == ECONNREFUSED || errno == EADDRNOTAVAIL
559         || errno == EAGAIN
560        ) {
561//TODO: always do this?
562            set_next(p, error_interval());
563            goto close_sock;
564        }
565        xfunc_die();
566    }
567
568    if (size != NTP_MSGSIZE_NOAUTH && size != NTP_MSGSIZE) {
569        bb_error_msg("malformed packet received from %s", p->p_dotted);
570        goto bail;
571    }
572
573    if (msg.m_orgtime.int_partl != p->p_xmt_msg.m_xmttime.int_partl
574     || msg.m_orgtime.fractionl != p->p_xmt_msg.m_xmttime.fractionl
575    ) {
576        goto bail;
577    }
578
579    if ((msg.m_status & LI_ALARM) == LI_ALARM
580     || msg.m_stratum == 0
581     || msg.m_stratum > NTP_MAXSTRATUM
582    ) {
583// TODO: stratum 0 responses may have commands in 32-bit m_refid field:
584// "DENY", "RSTR" - peer does not like us at all
585// "RATE" - peer is overloaded, reduce polling freq
586        interval = error_interval();
587        bb_error_msg("reply from %s: not synced, next query in %us", p->p_dotted, interval);
588        goto close_sock;
589    }
590
591    /*
592     * From RFC 2030 (with a correction to the delay math):
593     *
594     * Timestamp Name          ID   When Generated
595     * ------------------------------------------------------------
596     * Originate Timestamp     T1   time request sent by client
597     * Receive Timestamp       T2   time request received by server
598     * Transmit Timestamp      T3   time reply sent by server
599     * Destination Timestamp   T4   time reply received by client
600     *
601     * The roundtrip delay and local clock offset are defined as
602     *
603     * delay = (T4 - T1) - (T3 - T2); offset = ((T2 - T1) + (T3 - T4)) / 2
604     */
605    T1 = p->p_xmttime;
606    T2 = lfp_to_d(msg.m_rectime);
607    T3 = lfp_to_d(msg.m_xmttime);
608    T4 = gettime1900d();
609
610    datapoint = &p->p_datapoint[p->p_datapoint_idx];
611
612    datapoint->d_offset = ((T2 - T1) + (T3 - T4)) / 2;
613    datapoint->d_delay = (T4 - T1) - (T3 - T2);
614    if (datapoint->d_delay < 0) {
615        bb_error_msg("reply from %s: negative delay %f", p->p_dotted, datapoint->d_delay);
616        interval = error_interval();
617        set_next(p, interval);
618        goto close_sock;
619    }
620    //UNUSED: datapoint->d_error = (T2 - T1) - (T3 - T4);
621    datapoint->d_rcv_time = (time_t)(T4 - OFFSET_1900_1970); /* = time(NULL); */
622    datapoint->d_good = 1;
623
624    datapoint->d_leap = (msg.m_status & LI_MASK);
625    //UNUSED: datapoint->o_precision = msg.m_precision_exp;
626    //UNUSED: datapoint->o_rootdelay = sfp_to_d(msg.m_rootdelay);
627    //UNUSED: datapoint->o_rootdispersion = sfp_to_d(msg.m_dispersion);
628    //UNUSED: datapoint->d_refid = ntohl(msg.m_refid);
629    datapoint->d_refid4 = msg.m_xmttime.fractionl;
630    //UNUSED: datapoint->o_reftime = lfp_to_d(msg.m_reftime);
631    //UNUSED: datapoint->o_poll = msg.m_ppoll;
632    datapoint->d_stratum = msg.m_stratum;
633
634    if (p->p_trustlevel < TRUSTLEVEL_PATHETIC)
635        interval = scale_interval(INTERVAL_QUERY_PATHETIC);
636    else if (p->p_trustlevel < TRUSTLEVEL_AGRESSIVE)
637        interval = scale_interval(INTERVAL_QUERY_AGRESSIVE);
638    else
639        interval = scale_interval(INTERVAL_QUERY_NORMAL);
640
641    set_next(p, interval);
642
643    /* Every received reply which we do not discard increases trust */
644    if (p->p_trustlevel < TRUSTLEVEL_MAX) {
645        p->p_trustlevel++;
646        if (p->p_trustlevel == TRUSTLEVEL_BADPEER)
647            bb_error_msg("peer %s now valid", p->p_dotted);
648    }
649
650    if (G.verbose)
651        bb_error_msg("reply from %s: offset %f delay %f, next query in %us", p->p_dotted,
652            datapoint->d_offset, datapoint->d_delay, interval);
653
654    update_peer_data(p);
655//TODO: do it after all peers had a chance to return at least one reply?
656    step_time_once(datapoint->d_offset);
657
658    p->p_datapoint_idx++;
659    if (p->p_datapoint_idx >= NUM_DATAPOINTS)
660        p->p_datapoint_idx = 0;
661
662 close_sock:
663    /* We do not expect any more packets from this peer for now.
664     * Closing the socket informs kernel about it.
665     * We open a new socket when we send a new query.
666     */
667    close(p->p_fd);
668    p->p_fd = -1;
669 bail:
670    return;
671}
672
673#if ENABLE_FEATURE_NTPD_SERVER
674static void
675recv_and_process_client_pkt(void /*int fd*/)
676{
677    ssize_t          size;
678    uint8_t          version;
679    double           rectime;
680    len_and_sockaddr *to;
681    struct sockaddr  *from;
682    msg_t            msg;
683    uint8_t          query_status;
684    uint8_t          query_ppoll;
685    l_fixedpt_t      query_xmttime;
686
687    to = get_sock_lsa(G.listen_fd);
688    from = xzalloc(to->len);
689
690    size = recv_from_to(G.listen_fd, &msg, sizeof(msg), MSG_DONTWAIT, from, &to->u.sa, to->len);
691    if (size != NTP_MSGSIZE_NOAUTH && size != NTP_MSGSIZE) {
692        char *addr;
693        if (size < 0) {
694            if (errno == EAGAIN)
695                goto bail;
696            bb_perror_msg_and_die("recv");
697        }
698        addr = xmalloc_sockaddr2dotted_noport(from);
699        bb_error_msg("malformed packet received from %s: size %u", addr, (int)size);
700        free(addr);
701        goto bail;
702    }
703
704    query_status = msg.m_status;
705    query_ppoll = msg.m_ppoll;
706    query_xmttime = msg.m_xmttime;
707
708    /* Build a reply packet */
709    memset(&msg, 0, sizeof(msg));
710    msg.m_status = G.synced ? G.leap : LI_ALARM;
711    msg.m_status |= (query_status & VERSION_MASK);
712    msg.m_status |= ((query_status & MODE_MASK) == MODE_CLIENT) ?
713            MODE_SERVER : MODE_SYM_PAS;
714    msg.m_stratum = G.stratum;
715    msg.m_ppoll = query_ppoll;
716    msg.m_precision_exp = G_precision_exp;
717    rectime = gettime1900d();
718    msg.m_xmttime = msg.m_rectime = d_to_lfp(rectime);
719    msg.m_reftime = d_to_lfp(G.reftime);
720    //msg.m_xmttime = d_to_lfp(gettime1900d()); // = msg.m_rectime
721    msg.m_orgtime = query_xmttime;
722    msg.m_rootdelay = d_to_sfp(G.rootdelay);
723    version = (query_status & VERSION_MASK); /* ... >> VERSION_SHIFT - done below instead */
724    msg.m_refid = (version > (3 << VERSION_SHIFT)) ? G.refid4 : G.refid;
725
726    /* We reply from the local address packet was sent to,
727     * this makes to/from look swapped here: */
728    do_sendto(G.listen_fd,
729        /*from:*/ &to->u.sa, /*to:*/ from, /*addrlen:*/ to->len,
730        &msg, size);
731
732 bail:
733    free(to);
734    free(from);
735}
736#endif
737
738/* Upstream ntpd's options:
739 *
740 * -4   Force DNS resolution of host names to the IPv4 namespace.
741 * -6   Force DNS resolution of host names to the IPv6 namespace.
742 * -a   Require cryptographic authentication for broadcast client,
743 *      multicast client and symmetric passive associations.
744 *      This is the default.
745 * -A   Do not require cryptographic authentication for broadcast client,
746 *      multicast client and symmetric passive associations.
747 *      This is almost never a good idea.
748 * -b   Enable the client to synchronize to broadcast servers.
749 * -c conffile
750 *      Specify the name and path of the configuration file,
751 *      default /etc/ntp.conf
752 * -d   Specify debugging mode. This option may occur more than once,
753 *      with each occurrence indicating greater detail of display.
754 * -D level
755 *      Specify debugging level directly.
756 * -f driftfile
757 *      Specify the name and path of the frequency file.
758 *      This is the same operation as the "driftfile FILE"
759 *      configuration command.
760 * -g   Normally, ntpd exits with a message to the system log
761 *      if the offset exceeds the panic threshold, which is 1000 s
762 *      by default. This option allows the time to be set to any value
763 *      without restriction; however, this can happen only once.
764 *      If the threshold is exceeded after that, ntpd will exit
765 *      with a message to the system log. This option can be used
766 *      with the -q and -x options. See the tinker command for other options.
767 * -i jaildir
768 *      Chroot the server to the directory jaildir. This option also implies
769 *      that the server attempts to drop root privileges at startup
770 *      (otherwise, chroot gives very little additional security).
771 *      You may need to also specify a -u option.
772 * -k keyfile
773 *      Specify the name and path of the symmetric key file,
774 *      default /etc/ntp/keys. This is the same operation
775 *      as the "keys FILE" configuration command.
776 * -l logfile
777 *      Specify the name and path of the log file. The default
778 *      is the system log file. This is the same operation as
779 *      the "logfile FILE" configuration command.
780 * -L   Do not listen to virtual IPs. The default is to listen.
781 * -n   Don't fork.
782 * -N   To the extent permitted by the operating system,
783 *      run the ntpd at the highest priority.
784 * -p pidfile
785 *      Specify the name and path of the file used to record the ntpd
786 *      process ID. This is the same operation as the "pidfile FILE"
787 *      configuration command.
788 * -P priority
789 *      To the extent permitted by the operating system,
790 *      run the ntpd at the specified priority.
791 * -q   Exit the ntpd just after the first time the clock is set.
792 *      This behavior mimics that of the ntpdate program, which is
793 *      to be retired. The -g and -x options can be used with this option.
794 *      Note: The kernel time discipline is disabled with this option.
795 * -r broadcastdelay
796 *      Specify the default propagation delay from the broadcast/multicast
797 *      server to this client. This is necessary only if the delay
798 *      cannot be computed automatically by the protocol.
799 * -s statsdir
800 *      Specify the directory path for files created by the statistics
801 *      facility. This is the same operation as the "statsdir DIR"
802 *      configuration command.
803 * -t key
804 *      Add a key number to the trusted key list. This option can occur
805 *      more than once.
806 * -u user[:group]
807 *      Specify a user, and optionally a group, to switch to.
808 * -v variable
809 * -V variable
810 *      Add a system variable listed by default.
811 * -x   Normally, the time is slewed if the offset is less than the step
812 *      threshold, which is 128 ms by default, and stepped if above
813 *      the threshold. This option sets the threshold to 600 s, which is
814 *      well within the accuracy window to set the clock manually.
815 *      Note: since the slew rate of typical Unix kernels is limited
816 *      to 0.5 ms/s, each second of adjustment requires an amortization
817 *      interval of 2000 s. Thus, an adjustment as much as 600 s
818 *      will take almost 14 days to complete. This option can be used
819 *      with the -g and -q options. See the tinker command for other options.
820 *      Note: The kernel time discipline is disabled with this option.
821 */
822
823/* By doing init in a separate function we decrease stack usage
824 * in main loop.
825 */
826static NOINLINE void ntp_init(char **argv)
827{
828    unsigned opts;
829    llist_t *peers;
830
831    srandom(getpid());
832
833    if (getuid())
834        bb_error_msg_and_die(bb_msg_you_must_be_root);
835
836    peers = NULL;
837    opt_complementary = "dd:p::"; /* d: counter, p: list */
838    opts = getopt32(argv,
839            "nqNx" /* compat */
840            "p:"IF_FEATURE_NTPD_SERVER("l") /* NOT compat */
841            "d" /* compat */
842            "46aAbgL", /* compat, ignored */
843            &peers, &G.verbose);
844    if (!(opts & (OPT_p|OPT_l)))
845        bb_show_usage();
846    if (opts & OPT_x) /* disable stepping, only slew is allowed */
847        G.time_was_stepped = 1;
848    while (peers)
849        add_peers(llist_pop(&peers));
850    if (!(opts & OPT_n)) {
851        bb_daemonize_or_rexec(DAEMON_DEVNULL_STDIO, argv);
852        logmode = LOGMODE_NONE;
853    }
854#if ENABLE_FEATURE_NTPD_SERVER
855    G.listen_fd = -1;
856    if (opts & OPT_l) {
857        G.listen_fd = create_and_bind_dgram_or_die(NULL, 123);
858        socket_want_pktinfo(G.listen_fd);
859        setsockopt(G.listen_fd, IPPROTO_IP, IP_TOS, &const_IPTOS_LOWDELAY, sizeof(const_IPTOS_LOWDELAY));
860    }
861#endif
862    /* I hesitate to set -20 prio. -15 should be high enough for timekeeping */
863    if (opts & OPT_N)
864        setpriority(PRIO_PROCESS, 0, -15);
865
866    /* Set some globals */
867#if 0
868    /* With constant b = 100, G.precision_exp is also constant -6.
869     * Uncomment this and you'll see */
870    {
871        int prec = 0;
872        int b;
873# if 0
874        struct timespec tp;
875        /* We can use sys_clock_getres but assuming 10ms tick should be fine */
876        clock_getres(CLOCK_REALTIME, &tp);
877        tp.tv_sec = 0;
878        tp.tv_nsec = 10000000;
879        b = 1000000000 / tp.tv_nsec;  /* convert to Hz */
880# else
881        b = 100; /* b = 1000000000/10000000 = 100 */
882# endif
883        while (b > 1)
884            prec--, b >>= 1;
885        //G.precision_exp = prec;
886        bb_error_msg("G.precision_exp:%d", prec); /* -6 */
887    }
888#endif
889    G.scale = 1;
890
891    bb_signals((1 << SIGTERM) | (1 << SIGINT), record_signo);
892    bb_signals((1 << SIGPIPE) | (1 << SIGHUP), SIG_IGN);
893}
894
895int ntpd_main(int argc UNUSED_PARAM, char **argv) MAIN_EXTERNALLY_VISIBLE;
896int ntpd_main(int argc UNUSED_PARAM, char **argv)
897{
898    struct globals g;
899    struct pollfd *pfd;
900    peer_t **idx2peer;
901
902    memset(&g, 0, sizeof(g));
903    SET_PTR_TO_GLOBALS(&g);
904
905    ntp_init(argv);
906
907    {
908        /* if ENABLE_FEATURE_NTPD_SERVER, + 1 for listen_fd: */
909        unsigned cnt = g.peer_cnt + ENABLE_FEATURE_NTPD_SERVER;
910        idx2peer = xzalloc(sizeof(idx2peer[0]) * cnt);
911        pfd = xzalloc(sizeof(pfd[0]) * cnt);
912    }
913
914    while (!bb_got_signal) {
915        llist_t *item;
916        unsigned i, j;
917        unsigned sent_cnt, trial_cnt;
918        int nfds, timeout;
919        time_t cur_time, nextaction;
920
921        /* Nothing between here and poll() blocks for any significant time */
922
923        cur_time = time(NULL);
924        nextaction = cur_time + 3600;
925
926        i = 0;
927#if ENABLE_FEATURE_NTPD_SERVER
928        if (g.listen_fd != -1) {
929            pfd[0].fd = g.listen_fd;
930            pfd[0].events = POLLIN;
931            i++;
932        }
933#endif
934        /* Pass over peer list, send requests, time out on receives */
935        sent_cnt = trial_cnt = 0;
936        for (item = g.ntp_peers; item != NULL; item = item->link) {
937            peer_t *p = (peer_t *) item->data;
938
939            /* Overflow-safe "if (p->next_action_time <= cur_time) ..." */
940            if ((int)(cur_time - p->next_action_time) >= 0) {
941                if (p->p_fd == -1) {
942                    /* Time to send new req */
943                    trial_cnt++;
944                    if (send_query_to_peer(p) == 0)
945                        sent_cnt++;
946                } else {
947                    /* Timed out waiting for reply */
948                    close(p->p_fd);
949                    p->p_fd = -1;
950                    timeout = error_interval();
951                    bb_error_msg("timed out waiting for %s, "
952                            "next query in %us", p->p_dotted, timeout);
953                    if (p->p_trustlevel >= TRUSTLEVEL_BADPEER) {
954                        p->p_trustlevel /= 2;
955                        if (p->p_trustlevel < TRUSTLEVEL_BADPEER)
956                            bb_error_msg("peer %s now invalid", p->p_dotted);
957                    }
958                    set_next(p, timeout);
959                }
960            }
961
962            if (p->next_action_time < nextaction)
963                nextaction = p->next_action_time;
964
965            if (p->p_fd >= 0) {
966                /* Wait for reply from this peer */
967                pfd[i].fd = p->p_fd;
968                pfd[i].events = POLLIN;
969                idx2peer[i] = p;
970                i++;
971            }
972        }
973
974        if ((trial_cnt > 0 && sent_cnt == 0) || g.peer_cnt == 0)
975            step_time_once(0); /* no good peers, don't wait */
976
977        timeout = nextaction - cur_time;
978        if (timeout < 1)
979            timeout = 1;
980
981        /* Here we may block */
982        if (g.verbose >= 2)
983            bb_error_msg("poll %us, sockets:%u", timeout, i);
984        nfds = poll(pfd, i, timeout * 1000);
985        if (nfds <= 0)
986            continue;
987
988        /* Process any received packets */
989        j = 0;
990#if ENABLE_FEATURE_NTPD_SERVER
991        if (g.listen_fd != -1) {
992            if (pfd[0].revents /* & (POLLIN|POLLERR)*/) {
993                nfds--;
994                recv_and_process_client_pkt(/*g.listen_fd*/);
995            }
996            j = 1;
997        }
998#endif
999        for (; nfds != 0 && j < i; j++) {
1000            if (pfd[j].revents /* & (POLLIN|POLLERR)*/) {
1001                nfds--;
1002                recv_and_process_peer_pkt(idx2peer[j]);
1003            }
1004        }
1005    } /* while (!bb_got_signal) */
1006
1007    kill_myself_with_sig(bb_got_signal);
1008}
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