diff options
Diffstat (limited to 'networking')
| -rw-r--r-- | networking/ntpd.c | 1985 |
1 files changed, 1985 insertions, 0 deletions
diff --git a/networking/ntpd.c b/networking/ntpd.c new file mode 100644 index 000000000..508e355c9 --- /dev/null +++ b/networking/ntpd.c @@ -0,0 +1,1985 @@ +/* + * NTP client/server, based on OpenNTPD 3.9p1 + * + * Author: Adam Tkac <vonsch@gmail.com> + * + * Licensed under GPLv2, see file LICENSE in this tarball for details. + * + * Parts of OpenNTPD clock syncronization code is replaced by + * code which is based on ntp-4.2.6. It carries the following + * copyright notice: + * + *********************************************************************** + * * + * Copyright (c) University of Delaware 1992-2009 * + * * + * Permission to use, copy, modify, and distribute this software and * + * its documentation for any purpose with or without fee is hereby * + * granted, provided that the above copyright notice appears in all * + * copies and that both the copyright notice and this permission * + * notice appear in supporting documentation, and that the name * + * University of Delaware not be used in advertising or publicity * + * pertaining to distribution of the software without specific, * + * written prior permission. The University of Delaware makes no * + * representations about the suitability this software for any * + * purpose. It is provided "as is" without express or implied * + * warranty. * + * * + *********************************************************************** + */ +#include "libbb.h" +#include <math.h> +#include <netinet/ip.h> /* For IPTOS_LOWDELAY definition */ +#include <sys/timex.h> +#ifndef IPTOS_LOWDELAY +# define IPTOS_LOWDELAY 0x10 +#endif +#ifndef IP_PKTINFO +# error "Sorry, your kernel has to support IP_PKTINFO" +#endif + + +#define RETRY_INTERVAL 5 /* on error, retry in N secs */ +#define QUERYTIME_MAX 15 /* wait for reply up to N secs */ + +#define FREQ_TOLERANCE 15e-6 /* % frequency tolerance (15 PPM) */ +#define MINPOLL 4 /* % minimum poll interval (6: 64 s) */ +#define MAXPOLL 12 /* % maximum poll interval (12: 1.1h, 17: 36.4h) (was 17) */ +#define MINDISP 0.01 /* % minimum dispersion (s) */ +#define MAXDISP 16 /* maximum dispersion (s) */ +#define MAXSTRAT 16 /* maximum stratum (infinity metric) */ +#define MAXDIST 1 /* % distance threshold (s) */ +#define MIN_SELECTED 1 /* % minimum intersection survivors */ +#define MIN_CLUSTERED 3 /* % minimum cluster survivors */ + +#define MAXFREQ 0.000500 /* frequency tolerance (500 PPM) */ + +/* Clock discipline parameters and constants */ +#define STEP_THRESHOLD 0.128 /* step threshold (s) */ +#define WATCH_THRESHOLD 150 /* stepout threshold (s). std ntpd uses 900 (11 mins (!)) */ +/* NB: set WATCH_THRESHOLD to ~60 when debugging to save time) */ +#define PANIC_THRESHOLD 1000 /* panic threshold (s) */ + +/* Poll-adjust threshold. + * When we see that offset is small enough compared to discipline jitter, + * we grow a counter: += poll_ext. When it goes over POLLADJ_LIMIT, + * we poll_ext++. If offset isn't small, counter -= poll_ext*2, + * and when it goes below -POLLADJ_LIMIT, we poll_ext-- + */ +#define POLLADJ_LIMIT 30 +/* If offset < POLLADJ_GATE * discipline_jitter, then we can increase + * poll interval (we think we can't improve timekeeping + * by staying at smaller poll). + */ +#define POLLADJ_GATE 4 +/* Compromise Allan intercept (s). doc uses 1500, std ntpd uses 512 */ +#define ALLAN 512 +/* PLL loop gain */ +#define PLL 65536 +/* FLL loop gain [why it depends on MAXPOLL??] */ +#define FLL (MAXPOLL + 1) +/* Parameter averaging constant */ +#define AVG 4 + +/* Verbosity control (max level of -dddd options accepted). + * max 5 is very talkative (and bloated). 2 is non-bloated, + * production level setting. + */ +#define MAX_VERBOSE 2 + +#define VERB1 if (MAX_VERBOSE && G.verbose) +#define VERB2 if (MAX_VERBOSE >= 2 && G.verbose >= 2) +#define VERB3 if (MAX_VERBOSE >= 3 && G.verbose >= 3) +#define VERB4 if (MAX_VERBOSE >= 4 && G.verbose >= 4) +#define VERB5 if (MAX_VERBOSE >= 5 && G.verbose >= 5) + + +enum { + NTP_VERSION = 4, + NTP_MAXSTRATUM = 15, + + NTP_DIGESTSIZE = 16, + NTP_MSGSIZE_NOAUTH = 48, + NTP_MSGSIZE = (NTP_MSGSIZE_NOAUTH + 4 + NTP_DIGESTSIZE), + + /* Status Masks */ + MODE_MASK = (7 << 0), + VERSION_MASK = (7 << 3), + VERSION_SHIFT = 3, + LI_MASK = (3 << 6), + + /* Leap Second Codes (high order two bits of m_status) */ + LI_NOWARNING = (0 << 6), /* no warning */ + LI_PLUSSEC = (1 << 6), /* add a second (61 seconds) */ + LI_MINUSSEC = (2 << 6), /* minus a second (59 seconds) */ + LI_ALARM = (3 << 6), /* alarm condition */ + + /* Mode values */ + MODE_RES0 = 0, /* reserved */ + MODE_SYM_ACT = 1, /* symmetric active */ + MODE_SYM_PAS = 2, /* symmetric passive */ + MODE_CLIENT = 3, /* client */ + MODE_SERVER = 4, /* server */ + MODE_BROADCAST = 5, /* broadcast */ + MODE_RES1 = 6, /* reserved for NTP control message */ + MODE_RES2 = 7, /* reserved for private use */ +}; + +//TODO: better base selection +#define OFFSET_1900_1970 2208988800UL /* 1970 - 1900 in seconds */ + +#define NUM_DATAPOINTS 8 + +typedef struct { + uint32_t int_partl; + uint32_t fractionl; +} l_fixedpt_t; + +typedef struct { + uint16_t int_parts; + uint16_t fractions; +} s_fixedpt_t; + +typedef struct { + uint8_t m_status; /* status of local clock and leap info */ + uint8_t m_stratum; + uint8_t m_ppoll; /* poll value */ + int8_t m_precision_exp; + s_fixedpt_t m_rootdelay; + s_fixedpt_t m_rootdisp; + uint32_t m_refid; + l_fixedpt_t m_reftime; + l_fixedpt_t m_orgtime; + l_fixedpt_t m_rectime; + l_fixedpt_t m_xmttime; + uint32_t m_keyid; + uint8_t m_digest[NTP_DIGESTSIZE]; +} msg_t; + +typedef struct { + double d_recv_time; + double d_offset; + double d_dispersion; +} datapoint_t; + +typedef struct { + len_and_sockaddr *p_lsa; + char *p_dotted; + /* when to send new query (if p_fd == -1) + * or when receive times out (if p_fd >= 0): */ + time_t next_action_time; + int p_fd; + int datapoint_idx; + uint32_t lastpkt_refid; + uint8_t lastpkt_leap; + uint8_t lastpkt_stratum; + uint8_t p_reachable_bits; + double p_xmttime; + double lastpkt_recv_time; + double lastpkt_delay; + double lastpkt_rootdelay; + double lastpkt_rootdisp; + /* produced by filter algorithm: */ + double filter_offset; + double filter_dispersion; + double filter_jitter; + datapoint_t filter_datapoint[NUM_DATAPOINTS]; + /* last sent packet: */ + msg_t p_xmt_msg; +} peer_t; + + +enum { + OPT_n = (1 << 0), + OPT_q = (1 << 1), + OPT_N = (1 << 2), + OPT_x = (1 << 3), + /* Insert new options above this line. */ + /* Non-compat options: */ + OPT_p = (1 << 4), + OPT_l = (1 << 5) * ENABLE_FEATURE_NTPD_SERVER, +}; + +struct globals { + /* total round trip delay to currently selected reference clock */ + double rootdelay; + /* reference timestamp: time when the system clock was last set or corrected */ + double reftime; + /* total dispersion to currently selected reference clock */ + double rootdisp; + llist_t *ntp_peers; +#if ENABLE_FEATURE_NTPD_SERVER + int listen_fd; +#endif + unsigned verbose; + unsigned peer_cnt; + /* refid: 32-bit code identifying the particular server or reference clock + * in stratum 0 packets this is a four-character ASCII string, + * called the kiss code, used for debugging and monitoring + * in stratum 1 packets this is a four-character ASCII string + * assigned to the reference clock by IANA. Example: "GPS " + * in stratum 2+ packets, it's IPv4 address or 4 first bytes of MD5 hash of IPv6 + */ + uint32_t refid; + uint8_t leap; + /* precision is defined as the larger of the resolution and time to + * read the clock, in log2 units. For instance, the precision of a + * mains-frequency clock incrementing at 60 Hz is 16 ms, even when the + * system clock hardware representation is to the nanosecond. + * + * Delays, jitters of various kinds are clamper down to precision. + * + * If precision_sec is too large, discipline_jitter gets clamped to it + * and if offset is much smaller than discipline_jitter, poll interval + * grows even though we really can benefit from staying at smaller one, + * collecting non-lagged datapoits and correcting the offset. + * (Lagged datapoits exist when poll_exp is large but we still have + * systematic offset error - the time distance between datapoints + * is significat and older datapoints have smaller offsets. + * This makes our offset estimation a bit smaller than reality) + * Due to this effect, setting G_precision_sec close to + * STEP_THRESHOLD isn't such a good idea - offsets may grow + * too big and we will step. I observed it with -6. + * + * OTOH, setting precision too small would result in futile attempts + * to syncronize to the unachievable precision. + * + * -6 is 1/64 sec, -7 is 1/128 sec and so on. + */ +#define G_precision_exp -8 +#define G_precision_sec (1.0 / (1 << (- G_precision_exp))) + uint8_t stratum; + /* Bool. After set to 1, never goes back to 0: */ +//TODO: fix logic: +// uint8_t time_was_stepped; + uint8_t adjtimex_was_done; + + uint8_t discipline_state; // doc calls it c.state + uint8_t poll_exp; // s.poll + int polladj_count; // c.count + double discipline_jitter; // c.jitter + double last_update_offset; // c.last + double discipline_freq_drift; // c.freq +//TODO: conditionally calculate wander? it's used only for logging + double discipline_wander; // c.wander + double last_update_recv_time; // s.t +//TODO: add s.jitter - grep for it here and see clock_combine() in doc +}; +#define G (*ptr_to_globals) + +static const int const_IPTOS_LOWDELAY = IPTOS_LOWDELAY; + + +static double LOG2D(int a) +{ + if (a < 0) + return 1.0 / (1UL << -a); + return 1UL << a; +} +static ALWAYS_INLINE double SQUARE(double x) +{ + return x * x; +} +static ALWAYS_INLINE double MAXD(double a, double b) +{ + if (a > b) + return a; + return b; +} +static ALWAYS_INLINE double MIND(double a, double b) +{ + if (a < b) + return a; + return b; +} +#define SQRT(x) (sqrt(x)) + +static double +gettime1900d(void) +{ + struct timeval tv; + gettimeofday(&tv, NULL); /* never fails */ + return (tv.tv_sec + 1.0e-6 * tv.tv_usec + OFFSET_1900_1970); +} + +static void +d_to_tv(double d, struct timeval *tv) +{ + tv->tv_sec = (long)d; + tv->tv_usec = (d - tv->tv_sec) * 1000000; +} + +static double +lfp_to_d(l_fixedpt_t lfp) +{ + double ret; + lfp.int_partl = ntohl(lfp.int_partl); + lfp.fractionl = ntohl(lfp.fractionl); + ret = (double)lfp.int_partl + ((double)lfp.fractionl / UINT_MAX); + return ret; +} +static double +sfp_to_d(s_fixedpt_t sfp) +{ + double ret; + sfp.int_parts = ntohs(sfp.int_parts); + sfp.fractions = ntohs(sfp.fractions); + ret = (double)sfp.int_parts + ((double)sfp.fractions / USHRT_MAX); + return ret; +} +#if ENABLE_FEATURE_NTPD_SERVER +static l_fixedpt_t +d_to_lfp(double d) +{ + l_fixedpt_t lfp; + lfp.int_partl = (uint32_t)d; + lfp.fractionl = (uint32_t)((d - lfp.int_partl) * UINT_MAX); + lfp.int_partl = htonl(lfp.int_partl); + lfp.fractionl = htonl(lfp.fractionl); + return lfp; +} +static s_fixedpt_t +d_to_sfp(double d) +{ + s_fixedpt_t sfp; + sfp.int_parts = (uint16_t)d; + sfp.fractions = (uint16_t)((d - sfp.int_parts) * USHRT_MAX); + sfp.int_parts = htons(sfp.int_parts); + sfp.fractions = htons(sfp.fractions); + return sfp; +} +#endif + +static double +dispersion(const datapoint_t *dp, double t) +{ + return dp->d_dispersion + FREQ_TOLERANCE * (t - dp->d_recv_time); +} + +static double +root_distance(peer_t *p, double t) +{ + /* The root synchronization distance is the maximum error due to + * all causes of the local clock relative to the primary server. + * It is defined as half the total delay plus total dispersion + * plus peer jitter. + */ + return MAXD(MINDISP, p->lastpkt_rootdelay + p->lastpkt_delay) / 2 + + p->lastpkt_rootdisp + + p->filter_dispersion + + FREQ_TOLERANCE * (t - p->lastpkt_recv_time) + + p->filter_jitter; +} + +static void +set_next(peer_t *p, unsigned t) +{ + p->next_action_time = time(NULL) + t; +} + +/* + * Peer clock filter and its helpers + */ +static void +filter_datapoints(peer_t *p, double t) +{ + int i, idx; + double minoff, maxoff, wavg, sum, w; + double x = x; + + minoff = maxoff = p->filter_datapoint[0].d_offset; + for (i = 1; i < NUM_DATAPOINTS; i++) { + if (minoff > p->filter_datapoint[i].d_offset) + minoff = p->filter_datapoint[i].d_offset; + if (maxoff < p->filter_datapoint[i].d_offset) + maxoff = p->filter_datapoint[i].d_offset; + } + + idx = p->datapoint_idx; /* most recent datapoint */ + /* Average offset: + * Drop two outliers and take weighted average of the rest: + * most_recent/2 + older1/4 + older2/8 ... + older5/32 + older6/32 + * we use older6/32, not older6/64 since sum of weights should be 1: + * 1/2 + 1/4 + 1/8 + 1/16 + 1/32 + 1/32 = 1 + */ + wavg = 0; + w = 0.5; + // n-1 + // --- dispersion(i) + // filter_dispersion = \ ------------- + // / (i+1) + // --- 2 + // i=0 + sum = 0; + for (i = 0; i < NUM_DATAPOINTS; i++) { + VERB4 { + bb_error_msg("datapoint[%d]: off:%f disp:%f(%f) age:%f%s", + i, + p->filter_datapoint[idx].d_offset, + p->filter_datapoint[idx].d_dispersion, dispersion(&p->filter_datapoint[idx], t), + t - p->filter_datapoint[idx].d_recv_time, + (minoff == p->filter_datapoint[idx].d_offset || maxoff == p->filter_datapoint[idx].d_offset) + ? " (outlier by offset)" : "" + ); + } + + sum += dispersion(&p->filter_datapoint[idx], t) / (2 << i); + + if (minoff == p->filter_datapoint[idx].d_offset) { + minoff -= 1; + } else + if (maxoff == p->filter_datapoint[idx].d_offset) { + maxoff += 1; + } else { + x = p->filter_datapoint[idx].d_offset * w; + wavg += x; + w /= 2; + } + + idx = (idx - 1) & (NUM_DATAPOINTS - 1); + } + wavg += x; /* add another older6/64 to form older6/32 */ + p->filter_offset = wavg; + p->filter_dispersion = sum; + + // +----- -----+ ^ 1/2 + // | n-1 | + // | --- | + // 1 | \ 2 | + // filter_jitter = --- * | / (avg-offset_j) | + // n | --- | + // | j=0 | + // +----- -----+ + // where n is the number of valid datapoints in the filter (n > 1); + // if filter_jitter < precision then filter_jitter = precision + sum = 0; + for (i = 0; i < NUM_DATAPOINTS; i++) { + sum += SQUARE(wavg - p->filter_datapoint[i].d_offset); + } + sum = SQRT(sum) / NUM_DATAPOINTS; + p->filter_jitter = sum > G_precision_sec ? sum : G_precision_sec; + + VERB3 bb_error_msg("filter offset:%f disp:%f jitter:%f", + p->filter_offset, p->filter_dispersion, p->filter_jitter); + +} + +static void +reset_peer_stats(peer_t *p, double t, double offset) +{ + int i; + for (i = 0; i < NUM_DATAPOINTS; i++) { + if (offset < 16 * STEP_THRESHOLD) { + p->filter_datapoint[i].d_recv_time -= offset; + if (p->filter_datapoint[i].d_offset != 0) { + p->filter_datapoint[i].d_offset -= offset; + } + } else { + p->filter_datapoint[i].d_recv_time = t; + p->filter_datapoint[i].d_offset = 0; + p->filter_datapoint[i].d_dispersion = MAXDISP; + } + } + if (offset < 16 * STEP_THRESHOLD) { + p->lastpkt_recv_time -= offset; + } else { + p->p_reachable_bits = 0; + p->lastpkt_recv_time = t; + } + filter_datapoints(p, t); /* recalc p->filter_xxx */ + p->next_action_time -= (time_t)offset; + VERB5 bb_error_msg("%s->lastpkt_recv_time=%f", p->p_dotted, p->lastpkt_recv_time); +} + +static void +add_peers(char *s) +{ + peer_t *p; + + p = xzalloc(sizeof(*p)); + p->p_lsa = xhost2sockaddr(s, 123); + p->p_dotted = xmalloc_sockaddr2dotted_noport(&p->p_lsa->u.sa); + p->p_fd = -1; + p->p_xmt_msg.m_status = MODE_CLIENT | (NTP_VERSION << 3); + p->next_action_time = time(NULL); /* = set_next(p, 0); */ + reset_peer_stats(p, gettime1900d(), 16 * STEP_THRESHOLD); + /* Speed up initial sync: with small offsets from peers, + * 3 samples will sync + */ + p->filter_datapoint[6].d_dispersion = 0; + p->filter_datapoint[7].d_dispersion = 0; + + llist_add_to(&G.ntp_peers, p); + G.peer_cnt++; +} + +static int +do_sendto(int fd, + const struct sockaddr *from, const struct sockaddr *to, socklen_t addrlen, + msg_t *msg, ssize_t len) +{ + ssize_t ret; + + errno = 0; + if (!from) { + ret = sendto(fd, msg, len, MSG_DONTWAIT, to, addrlen); + } else { + ret = send_to_from(fd, msg, len, MSG_DONTWAIT, to, from, addrlen); + } + if (ret != len) { + bb_perror_msg("send failed"); + return -1; + } + return 0; +} + +static int +send_query_to_peer(peer_t *p) +{ + // Why do we need to bind()? + // See what happens when we don't bind: + // + // socket(PF_INET, SOCK_DGRAM, IPPROTO_IP) = 3 + // setsockopt(3, SOL_IP, IP_TOS, [16], 4) = 0 + // gettimeofday({1259071266, 327885}, NULL) = 0 + // sendto(3, "xxx", 48, MSG_DONTWAIT, {sa_family=AF_INET, sin_port=htons(123), sin_addr=inet_addr("10.34.32.125")}, 16) = 48 + // ^^^ we sent it from some source port picked by kernel. + // time(NULL) = 1259071266 + // write(2, "ntpd: entering poll 15 secs\n", 28) = 28 + // poll([{fd=3, events=POLLIN}], 1, 15000) = 1 ([{fd=3, revents=POLLIN}]) + // recv(3, "yyy", 68, MSG_DONTWAIT) = 48 + // ^^^ this recv will receive packets to any local port! + // + // Uncomment this and use strace to see it in action: +#define PROBE_LOCAL_ADDR // { len_and_sockaddr lsa; lsa.len = LSA_SIZEOF_SA; getsockname(p->query.fd, &lsa.u.sa, &lsa.len); } + + if (p->p_fd == -1) { + int fd, family; + len_and_sockaddr *local_lsa; + + family = p->p_lsa->u.sa.sa_family; + p->p_fd = fd = xsocket_type(&local_lsa, family, SOCK_DGRAM); + /* local_lsa has "null" address and port 0 now. + * bind() ensures we have a *particular port* selected by kernel + * and remembered in p->p_fd, thus later recv(p->p_fd) + * receives only packets sent to this port. + */ + PROBE_LOCAL_ADDR + xbind(fd, &local_lsa->u.sa, local_lsa->len); + PROBE_LOCAL_ADDR +#if ENABLE_FEATURE_IPV6 + if (family == AF_INET) +#endif + setsockopt(fd, IPPROTO_IP, IP_TOS, &const_IPTOS_LOWDELAY, sizeof(const_IPTOS_LOWDELAY)); + free(local_lsa); + } + + /* + * Send out a random 64-bit number as our transmit time. The NTP + * server will copy said number into the originate field on the + * response that it sends us. This is totally legal per the SNTP spec. + * + * The impact of this is two fold: we no longer send out the current + * system time for the world to see (which may aid an attacker), and + * it gives us a (not very secure) way of knowing that we're not + * getting spoofed by an attacker that can't capture our traffic + * but can spoof packets from the NTP server we're communicating with. + * + * Save the real transmit timestamp locally. + */ + p->p_xmt_msg.m_xmttime.int_partl = random(); + p->p_xmt_msg.m_xmttime.fractionl = random(); + p->p_xmttime = gettime1900d(); + + if (do_sendto(p->p_fd, /*from:*/ NULL, /*to:*/ &p->p_lsa->u.sa, /*addrlen:*/ p->p_lsa->len, + &p->p_xmt_msg, NTP_MSGSIZE_NOAUTH) == -1 + ) { + close(p->p_fd); + p->p_fd = -1; + set_next(p, RETRY_INTERVAL); + return -1; + } + + p->p_reachable_bits <<= 1; + VERB1 bb_error_msg("sent query to %s", p->p_dotted); + set_next(p, QUERYTIME_MAX); + + return 0; +} + + +static void +step_time(double offset) +{ + double dtime; + struct timeval tv; + char buf[80]; + time_t tval; + + gettimeofday(&tv, NULL); /* never fails */ + dtime = offset + tv.tv_sec; + dtime += 1.0e-6 * tv.tv_usec; + d_to_tv(dtime, &tv); + + if (settimeofday(&tv, NULL) == -1) + bb_perror_msg_and_die("settimeofday"); + + tval = tv.tv_sec; + strftime(buf, sizeof(buf), "%a %b %e %H:%M:%S %Z %Y", localtime(&tval)); + + bb_error_msg("setting clock to %s (offset %fs)", buf, offset); + +// G.time_was_stepped = 1; +} + + +/* + * Selection and clustering, and their helpers + */ +typedef struct { + peer_t *p; + int type; + double edge; +} point_t; +static int +compare_point_edge(const void *aa, const void *bb) +{ + const point_t *a = aa; + const point_t *b = bb; + if (a->edge < b->edge) { + return -1; + } + return (a->edge > b->edge); +} +typedef struct { + peer_t *p; + double metric; +} survivor_t; +static int +compare_survivor_metric(const void *aa, const void *bb) +{ + const survivor_t *a = aa; + const survivor_t *b = bb; + if (a->metric < b->metric) + return -1; + return (a->metric > b->metric); +} +static int +fit(peer_t *p, double rd) +{ + if (p->p_reachable_bits == 0) { + VERB3 bb_error_msg("peer %s unfit for selection: unreachable", p->p_dotted); + return 0; + } +//TODO: we never accept such packets anyway, right? + if ((p->lastpkt_leap & LI_ALARM) == LI_ALARM + || p->lastpkt_stratum >= MAXSTRAT + ) { + VERB3 bb_error_msg("peer %s unfit for selection: bad status/stratum", p->p_dotted); + return 0; + } + /* rd is root_distance(p, t) */ + if (rd > MAXDIST + FREQ_TOLERANCE * (1 << G.poll_exp)) { + VERB3 bb_error_msg("peer %s unfit for selection: root distance too high", p->p_dotted); + return 0; + } +//TODO +// /* Do we have a loop? */ +// if (p->refid == p->dstaddr || p->refid == s.refid) +// return 0; + return 1; +} +static peer_t* +select_and_cluster(double t) +{ + llist_t *item; + int i, j; + int size = 3 * G.peer_cnt; + /* for selection algorithm */ + point_t point[size]; + unsigned num_points, num_candidates; + double low, high; + unsigned num_falsetickers; + /* for cluster algorithm */ + survivor_t survivor[size]; + unsigned num_survivors; + + /* Selection */ + + num_points = 0; + item = G.ntp_peers; + while (item != NULL) { + peer_t *p = (peer_t *) item->data; + double rd = root_distance(p, t); + double offset = p->filter_offset; + + if (!fit(p, rd)) { + item = item->link; + continue; + } + + VERB4 bb_error_msg("interval: [%f %f %f] %s", + offset - rd, + offset, + offset + rd, + p->p_dotted + ); + point[num_points].p = p; + point[num_points].type = -1; + point[num_points].edge = offset - rd; + num_points++; + point[num_points].p = p; + point[num_points].type = 0; + point[num_points].edge = offset; + num_points++; + point[num_points].p = p; + point[num_points].type = 1; + point[num_points].edge = offset + rd; + num_points++; + item = item->link; + } + num_candidates = num_points / 3; + if (num_candidates == 0) { + VERB3 bb_error_msg("no valid datapoints, no peer selected"); + return NULL; /* never happers? */ + } +//TODO: sorting does not seem to be done in reference code + qsort(point, num_points, sizeof(point[0]), compare_point_edge); + + /* Start with the assumption that there are no falsetickers. + * Attempt to find a nonempty intersection interval containing + * the midpoints of all truechimers. + * If a nonempty interval cannot be found, increase the number + * of assumed falsetickers by one and try again. + * If a nonempty interval is found and the number of falsetickers + * is less than the number of truechimers, a majority has been found + * and the midpoint of each truechimer represents + * the candidates available to the cluster algorithm. + */ + num_falsetickers = 0; + while (1) { + int c; + unsigned num_midpoints = 0; + + low = 1 << 9; + high = - (1 << 9); + c = 0; + for (i = 0; i < num_points; i++) { + /* We want to do: + * if (point[i].type == -1) c++; + * if (point[i].type == 1) c--; + * and it's simpler to do it this way: + */ + c -= point[i].type; + if (c >= num_candidates - num_falsetickers) { + /* If it was c++ and it got big enough... */ + low = point[i].edge; + break; + } + if (point[i].type == 0) + num_midpoints++; + } + c = 0; + for (i = num_points-1; i >= 0; i--) { + c += point[i].type; + if (c >= num_candidates - num_falsetickers) { + high = point[i].edge; + break; + } + if (point[i].type == 0) + num_midpoints++; + } + /* If the number of midpoints is greater than the number + * of allowed falsetickers, the intersection contains at + * least one truechimer with no midpoint - bad. + * Also, interval should be nonempty. + */ + if (num_midpoints <= num_falsetickers && low < high) + break; + num_falsetickers++; + if (num_falsetickers * 2 >= num_candidates) { + VERB3 bb_error_msg("too many falsetickers:%d (candidates:%d), no peer selected", + num_falsetickers, num_candidates); + return NULL; + } + } + VERB3 bb_error_msg("selected interval: [%f, %f]; candidates:%d falsetickers:%d", + low, high, num_candidates, num_falsetickers); + + /* Clustering */ + + /* Construct a list of survivors (p, metric) + * from the chime list, where metric is dominated + * first by stratum and then by root distance. + * All other things being equal, this is the order of preference. + */ + num_survivors = 0; + for (i = 0; i < num_points; i++) { + peer_t *p; + + if (point[i].edge < low || point[i].edge > high) + continue; + p = point[i].p; + survivor[num_survivors].p = p; +//TODO: save root_distance in point_t and reuse here? + survivor[num_survivors].metric = MAXDIST * p->lastpkt_stratum + root_distance(p, t); + VERB4 bb_error_msg("survivor[%d] metric:%f peer:%s", + num_survivors, survivor[num_survivors].metric, p->p_dotted); + num_survivors++; + } + /* There must be at least MIN_SELECTED survivors to satisfy the + * correctness assertions. Ordinarily, the Byzantine criteria + * require four survivors, but for the demonstration here, one + * is acceptable. + */ + if (num_survivors < MIN_SELECTED) { + VERB3 bb_error_msg("num_survivors %d < %d, no peer selected", + num_survivors, MIN_SELECTED); + return NULL; + } + +//looks like this is ONLY used by the fact that later we pick survivor[0]. +//we can avoid sorting then, just find the minimum once! + qsort(survivor, num_survivors, sizeof(survivor[0]), compare_survivor_metric); + + /* For each association p in turn, calculate the selection + * jitter p->sjitter as the square root of the sum of squares + * (p->offset - q->offset) over all q associations. The idea is + * to repeatedly discard the survivor with maximum selection + * jitter until a termination condition is met. + */ + while (1) { + unsigned max_idx = max_idx; + double max_selection_jitter = max_selection_jitter; + double min_jitter = min_jitter; + + if (num_survivors <= MIN_CLUSTERED) { + bb_error_msg("num_survivors %d <= %d, not discarding more", + num_survivors, MIN_CLUSTERED); + break; + } + + /* To make sure a few survivors are left + * for the clustering algorithm to chew on, + * we stop if the number of survivors + * is less than or equal to MIN_CLUSTERED (3). + */ + for (i = 0; i < num_survivors; i++) { + double selection_jitter_sq; + peer_t *p = survivor[i].p; + + if (i == 0 || p->filter_jitter < min_jitter) + min_jitter = p->filter_jitter; + + selection_jitter_sq = 0; + for (j = 0; j < num_survivors; j++) { + peer_t *q = survivor[j].p; +//TODO: where is 1/(n-1) * ... multiplier? + selection_jitter_sq += SQUARE(p->filter_offset - q->filter_offset); + } + if (i == 0 || selection_jitter_sq > max_selection_jitter) { + max_selection_jitter = selection_jitter_sq; + max_idx = i; + } + VERB5 bb_error_msg("survivor %d selection_jitter^2:%f", + i, selection_jitter_sq); + } + max_selection_jitter = SQRT(max_selection_jitter); + VERB4 bb_error_msg("max_selection_jitter (at %d):%f min_jitter:%f", + max_idx, max_selection_jitter, min_jitter); + + /* If the maximum selection jitter is less than the + * minimum peer jitter, then tossing out more survivors + * will not lower the minimum peer jitter, so we might + * as well stop. + */ + if (max_selection_jitter < min_jitter) { + VERB3 bb_error_msg("max_selection_jitter:%f < min_jitter:%f, num_survivors:%d, not discarding more", + max_selection_jitter, min_jitter, num_survivors); + break; + } + + /* Delete survivor[max_idx] from the list + * and go around again. + */ + VERB5 bb_error_msg("dropping survivor %d", max_idx); + num_survivors--; + while (max_idx < num_survivors) { + survivor[max_idx] = survivor[max_idx + 1]; + max_idx++; + } + } + + /* Pick the best clock. If the old system peer is on the list + * and at the same stratum as the first survivor on the list, + * then don't do a clock hop. Otherwise, select the first + * survivor on the list as the new system peer. + */ +//TODO - see clock_combine() + VERB3 bb_error_msg("selected peer %s filter_offset:%f age:%f", + survivor[0].p->p_dotted, + survivor[0].p->filter_offset, + t - survivor[0].p->lastpkt_recv_time + ); + return survivor[0].p; +} + + +/* + * Local clock discipline and its helpers + */ +static void +set_new_values(int disc_state, double offset, double recv_time) +{ + /* Enter new state and set state variables. Note we use the time + * of the last clock filter sample, which must be earlier than + * the current time. + */ + VERB3 bb_error_msg("disc_state=%d last_update_offset=%f last_update_recv_time=%f", + disc_state, offset, recv_time); + G.discipline_state = disc_state; + G.last_update_offset = offset; + G.last_update_recv_time = recv_time; +} +/* Clock state definitions */ +#define STATE_NSET 0 /* initial state, "nothing is set" */ +#define STATE_FSET 1 /* frequency set from file */ +#define STATE_SPIK 2 /* spike detected */ +#define STATE_FREQ 3 /* initial frequency */ +#define STATE_SYNC 4 /* clock synchronized (normal operation) */ +/* Return: -1: decrease poll interval, 0: leave as is, 1: increase */ +static int +update_local_clock(peer_t *p, double t) +{ + int rc; + long old_tmx_offset; + struct timex tmx; + double offset = p->filter_offset; + double recv_time = p->lastpkt_recv_time; + double abs_offset; + double freq_drift; + double since_last_update; + double etemp, dtemp; + + abs_offset = fabs(offset); + + /* If the offset is too large, give up and go home */ + if (abs_offset > PANIC_THRESHOLD) { + bb_error_msg_and_die("offset %f far too big, exiting", offset); + } + + /* If this is an old update, for instance as the result + * of a system peer change, avoid it. We never use + * an old sample or the same sample twice. + */ + if (recv_time <= G.last_update_recv_time) { + VERB3 bb_error_msg("same or older datapoint: %f >= %f, not using it", + G.last_update_recv_time, recv_time); + return 0; /* "leave poll interval as is" */ + } + + /* Clock state machine transition function. This is where the + * action is and defines how the system reacts to large time + * and frequency errors. + */ + since_last_update = recv_time - G.reftime; + freq_drift = 0; + if (G.discipline_state == STATE_FREQ) { + /* Ignore updates until the stepout threshold */ + if (since_last_update < WATCH_THRESHOLD) { + VERB3 bb_error_msg("measuring drift, datapoint ignored, %f sec remains", + WATCH_THRESHOLD - since_last_update); + return 0; /* "leave poll interval as is" */ + } + freq_drift = (offset - G.last_update_offset) / since_last_update; + } + + /* There are two main regimes: when the + * offset exceeds the step threshold and when it does not. + */ + if (abs_offset > STEP_THRESHOLD) { + llist_t *item; + + switch (G.discipline_state) { + case STATE_SYNC: + /* The first outlyer: ignore it, switch to SPIK state */ + VERB3 bb_error_msg("offset:%f - spike detected", offset); + G.discipline_state = STATE_SPIK; + return -1; /* "decrease poll interval" */ + + case STATE_SPIK: + /* Ignore succeeding outlyers until either an inlyer + * is found or the stepout threshold is exceeded. + */ + if (since_last_update < WATCH_THRESHOLD) { + VERB3 bb_error_msg("spike detected, datapoint ignored, %f sec remains", + WATCH_THRESHOLD - since_last_update); + return -1; /* "decrease poll interval" */ + } + /* fall through: we need to step */ + } /* switch */ + + /* Step the time and clamp down the poll interval. + * + * In NSET state an initial frequency correction is + * not available, usually because the frequency file has + * not yet been written. Since the time is outside the + * capture range, the clock is stepped. The frequency + * will be set directly following the stepout interval. + * + * In FSET state the initial frequency has been set + * from the frequency file. Since the time is outside + * the capture range, the clock is stepped immediately, + * rather than after the stepout interval. Guys get + * nervous if it takes 17 minutes to set the clock for + * the first time. + * + * In SPIK state the stepout threshold has expired and + * the phase is still above the step threshold. Note + * that a single spike greater than the step threshold + * is always suppressed, even at the longer poll + * intervals. + */ + VERB3 bb_error_msg("stepping time by %f; poll_exp=MINPOLL", offset); + step_time(offset); + if (option_mask32 & OPT_q) { + /* We were only asked to set time once. Done. */ + exit(0); + } + + G.polladj_count = 0; + G.poll_exp = MINPOLL; + G.stratum = MAXSTRAT; + for (item = G.ntp_peers; item != NULL; item = item->link) { + peer_t *pp = (peer_t *) item->data; + reset_peer_stats(pp, t, offset); + } + if (G.discipline_state == STATE_NSET) { + set_new_values(STATE_FREQ, /*offset:*/ 0, recv_time); + return 1; /* "ok to increase poll interval" */ + } + set_new_values(STATE_SYNC, /*offset:*/ 0, recv_time); + + } else { /* abs_offset <= STEP_THRESHOLD */ + + if (G.poll_exp < MINPOLL) { + VERB3 bb_error_msg("saw small offset %f, disabling burst mode", offset); + G.poll_exp = MINPOLL; + } + + /* Compute the clock jitter as the RMS of exponentially + * weighted offset differences. Used by the poll adjust code. + */ + etemp = SQUARE(G.discipline_jitter); + dtemp = SQUARE(MAXD(fabs(offset - G.last_update_offset), G_precision_sec)); + G.discipline_jitter = SQRT(etemp + (dtemp - etemp) / AVG); + VERB3 bb_error_msg("discipline jitter=%f", G.discipline_jitter); + + switch (G.discipline_state) { + case STATE_NSET: + if (option_mask32 & OPT_q) { + /* We were only asked to set time once. + * The clock is precise enough, no need to step. + */ + exit(0); + } + /* This is the first update received and the frequency + * has not been initialized. The first thing to do + * is directly measure the oscillator frequency. + */ + set_new_values(STATE_FREQ, offset, recv_time); + VERB3 bb_error_msg("transitioning to FREQ, datapoint ignored"); + return -1; /* "decrease poll interval" */ + +#if 0 /* this is dead code for now */ + case STATE_FSET: + /* This is the first update and the frequency + * has been initialized. Adjust the phase, but + * don't adjust the frequency until the next update. + */ + set_new_values(STATE_SYNC, offset, recv_time); + /* freq_drift remains 0 */ + break; +#endif + + case STATE_FREQ: + /* since_last_update >= WATCH_THRESHOLD, we waited enough. + * Correct the phase and frequency and switch to SYNC state. + * freq_drift was already estimated (see code above) + */ + set_new_values(STATE_SYNC, offset, recv_time); + break; + + default: + /* Compute freq_drift due to PLL and FLL contributions. + * + * The FLL and PLL frequency gain constants + * depend on the poll interval and Allan + * intercept. The FLL is not used below one-half + * the Allan intercept. Above that the loop gain + * increases in steps to 1 / AVG. + */ + if ((1 << G.poll_exp) > ALLAN / 2) { + etemp = FLL - G.poll_exp; + if (etemp < AVG) + etemp = AVG; + freq_drift += (offset - G.last_update_offset) / (MAXD(since_last_update, ALLAN) * etemp); + } + /* For the PLL the integration interval + * (numerator) is the minimum of the update + * interval and poll interval. This allows + * oversampling, but not undersampling. + */ + etemp = MIND(since_last_update, (1 << G.poll_exp)); + dtemp = (4 * PLL) << G.poll_exp; + freq_drift += offset * etemp / SQUARE(dtemp); + set_new_values(STATE_SYNC, offset, recv_time); + break; + } + G.stratum = p->lastpkt_stratum + 1; + } + + G.reftime = t; + G.leap = p->lastpkt_leap; + G.refid = p->lastpkt_refid; + G.rootdelay = p->lastpkt_rootdelay + p->lastpkt_delay; + dtemp = p->filter_jitter; // SQRT(SQUARE(p->filter_jitter) + SQUARE(s.jitter)); + dtemp += MAXD(p->filter_dispersion + FREQ_TOLERANCE * (t - p->lastpkt_recv_time) + abs_offset, MINDISP); + G.rootdisp = p->lastpkt_rootdisp + dtemp; + VERB3 bb_error_msg("updating leap/refid/reftime/rootdisp from peer %s", p->p_dotted); + + /* We are in STATE_SYNC now, but did not do adjtimex yet. + * (Any other state does not reach this, they all return earlier) + * By this time, freq_drift and G.last_update_offset are set + * to values suitable for adjtimex. + * + * Calculate the new frequency drift and frequency stability (wander). + * Compute the clock wander as the RMS of exponentially weighted + * frequency differences. This is not used directly, but can, + * along with the jitter, be a highly useful monitoring and + * debugging tool. + */ + dtemp = G.discipline_freq_drift + freq_drift; + G.discipline_freq_drift = MAXD(MIND(MAXFREQ, dtemp), -MAXFREQ); + etemp = SQUARE(G.discipline_wander); + dtemp = SQUARE(dtemp); + G.discipline_wander = SQRT(etemp + (dtemp - etemp) / AVG); + + VERB3 { + bb_error_msg("discipline freq_drift=%.9f(int:%ld corr:%e) wander=%f", + G.discipline_freq_drift, + (long)(G.discipline_freq_drift * 65536e6), + freq_drift, + G.discipline_wander); + memset(&tmx, 0, sizeof(tmx)); + if (adjtimex(&tmx) < 0) + bb_perror_msg_and_die("adjtimex"); + VERB3 bb_error_msg("p adjtimex freq:%ld offset:%ld constant:%ld status:0x%x", + tmx.freq, tmx.offset, tmx.constant, tmx.status); + } + + old_tmx_offset = 0; + if (!G.adjtimex_was_done) { + G.adjtimex_was_done = 1; + /* When we use adjtimex for the very first time, + * we need to ADD to pre-existing tmx.offset - it may be !0 + */ + memset(&tmx, 0, sizeof(tmx)); + if (adjtimex(&tmx) < 0) + bb_perror_msg_and_die("adjtimex"); + old_tmx_offset = tmx.offset; + } + memset(&tmx, 0, sizeof(tmx)); +#if 0 +//doesn't work, offset remains 0 (!): +//ntpd: set adjtimex freq:1786097 tmx.offset:77487 +//ntpd: prev adjtimex freq:1786097 tmx.offset:0 +//ntpd: cur adjtimex freq:1786097 tmx.offset:0 + tmx.modes = ADJ_FREQUENCY | ADJ_OFFSET; + /* 65536 is one ppm */ + tmx.freq = G.discipline_freq_drift * 65536e6; + tmx.offset = G.last_update_offset * 1000000; /* usec */ +#endif + tmx.modes = ADJ_OFFSET | ADJ_STATUS | ADJ_TIMECONST;// | ADJ_MAXERROR | ADJ_ESTERROR; + tmx.offset = (G.last_update_offset * 1000000) /* usec */ + /* + (G.last_update_offset < 0 ? -0.5 : 0.5) - too small to bother */ + + old_tmx_offset; /* almost always 0 */ + tmx.status = STA_PLL; + //if (sys_leap == LEAP_ADDSECOND) + // tmx.status |= STA_INS; + //else if (sys_leap == LEAP_DELSECOND) + // tmx.status |= STA_DEL; + tmx.constant = G.poll_exp - 4; + //tmx.esterror = (u_int32)(clock_jitter * 1e6); + //tmx.maxerror = (u_int32)((sys_rootdelay / 2 + sys_rootdisp) * 1e6); + VERB3 bb_error_msg("b adjtimex freq:%ld offset:%ld constant:%ld status:0x%x", + tmx.freq, tmx.offset, tmx.constant, tmx.status); + rc = adjtimex(&tmx); + if (rc < 0) + bb_perror_msg_and_die("adjtimex"); + VERB3 { + bb_error_msg("adjtimex:%d freq:%ld offset:%ld constant:%ld status:0x%x", + rc, tmx.freq, tmx.offset, tmx.constant, tmx.status); + memset(&tmx, 0, sizeof(tmx)); + if (adjtimex(&tmx) < 0) + bb_perror_msg_and_die("adjtimex"); + VERB3 bb_error_msg("c adjtimex freq:%ld offset:%ld constant:%ld status:0x%x", + tmx.freq, tmx.offset, tmx.constant, tmx.status); + } +// #define STA_MODE 0x4000 /* mode (0 = PLL, 1 = FLL) (ro) */ - ? +// it appeared after a while: +//ntpd: p adjtimex freq:-14545653 offset:-5396 constant:10 status:0x41 +//ntpd: c adjtimex freq:-14547835 offset:-8307 constant:10 status:0x1 +//ntpd: p adjtimex freq:-14547835 offset:-6398 constant:10 status:0x41 +//ntpd: c adjtimex freq:-14550486 offset:-10158 constant:10 status:0x1 +//ntpd: p adjtimex freq:-14550486 offset:-6132 constant:10 status:0x41 +//ntpd: c adjtimex freq:-14636129 offset:-10158 constant:10 status:0x4001 +//ntpd: p adjtimex freq:-14636129 offset:-10002 constant:10 status:0x4041 +//ntpd: c adjtimex freq:-14636245 offset:-7497 constant:10 status:0x1 +//ntpd: p adjtimex freq:-14636245 offset:-4573 constant:10 status:0x41 +//ntpd: c adjtimex freq:-14642034 offset:-11715 constant:10 status:0x1 +//ntpd: p adjtimex freq:-14642034 offset:-4098 constant:10 status:0x41 +//ntpd: c adjtimex freq:-14699112 offset:-11746 constant:10 status:0x4001 +//ntpd: p adjtimex freq:-14699112 offset:-4239 constant:10 status:0x4041 +//ntpd: c adjtimex freq:-14762330 offset:-12786 constant:10 status:0x4001 +//ntpd: p adjtimex freq:-14762330 offset:-4434 constant:10 status:0x4041 +//ntpd: b adjtimex freq:0 offset:-9669 constant:8 status:0x1 +//ntpd: adjtimex:0 freq:-14809095 offset:-9669 constant:10 status:0x4001 +//ntpd: c adjtimex freq:-14809095 offset:-9669 constant:10 status:0x4001 + + return 1; /* "ok to increase poll interval" */ +} + + +/* + * We've got a new reply packet from a peer, process it + * (helpers first) + */ +static unsigned +retry_interval(void) +{ + /* Local problem, want to retry soon */ + unsigned interval, r; + interval = RETRY_INTERVAL; + r = random(); + interval += r % (unsigned)(RETRY_INTERVAL / 4); + VERB3 bb_error_msg("chose retry interval:%u", interval); + return interval; +} +static unsigned +poll_interval(int exponent) /* exp is always -1 or 0 */ +{ + /* Want to send next packet at (1 << G.poll_exp) + small random value */ + unsigned interval, r; + exponent += G.poll_exp; /* G.poll_exp is always > 0 */ + /* never true: if (exp < 0) exp = 0; */ + interval = 1 << exponent; + r = random(); + interval += ((r & (interval-1)) >> 4) + ((r >> 8) & 1); /* + 1/16 of interval, max */ + VERB3 bb_error_msg("chose poll interval:%u (poll_exp:%d exp:%d)", interval, G.poll_exp, exponent); + return interval; +} +static void +recv_and_process_peer_pkt(peer_t *p) +{ + int rc; + ssize_t size; + msg_t msg; + double T1, T2, T3, T4; + unsigned interval; + datapoint_t *datapoint; + peer_t *q; + + /* We can recvfrom here and check from.IP, but some multihomed + * ntp servers reply from their *other IP*. + * TODO: maybe we should check at least what we can: from.port == 123? + */ + size = recv(p->p_fd, &msg, sizeof(msg), MSG_DONTWAIT); + if (size == -1) { + bb_perror_msg("recv(%s) error", p->p_dotted); + if (errno == EHOSTUNREACH || errno == EHOSTDOWN + || errno == ENETUNREACH || errno == ENETDOWN + || errno == ECONNREFUSED || errno == EADDRNOTAVAIL + || errno == EAGAIN + ) { +//TODO: always do this? + set_next(p, retry_interval()); + goto close_sock; + } + xfunc_die(); + } + + if (size != NTP_MSGSIZE_NOAUTH && size != NTP_MSGSIZE) { + bb_error_msg("malformed packet received from %s", p->p_dotted); + goto bail; + } + + if (msg.m_orgtime.int_partl != p->p_xmt_msg.m_xmttime.int_partl + || msg.m_orgtime.fractionl != p->p_xmt_msg.m_xmttime.fractionl + ) { + goto bail; + } + + if ((msg.m_status & LI_ALARM) == LI_ALARM + || msg.m_stratum == 0 + || msg.m_stratum > NTP_MAXSTRATUM + ) { +// TODO: stratum 0 responses may have commands in 32-bit m_refid field: +// "DENY", "RSTR" - peer does not like us at all +// "RATE" - peer is overloaded, reduce polling freq + interval = poll_interval(0); + bb_error_msg("reply from %s: not synced, next query in %us", p->p_dotted, interval); + goto close_sock; + } + +// /* +// * Verify the server is synchronized with valid stratum and +// * reference time not later than the transmit time. +// */ +// if (p->lastpkt_leap == NOSYNC || p->lastpkt_stratum >= MAXSTRAT) +// return; /* unsynchronized */ +// +// /* Verify valid root distance */ +// if (msg.m_rootdelay / 2 + msg.m_rootdisp >= MAXDISP || p->lastpkt_reftime > msg.m_xmt) +// return; /* invalid header values */ + + p->lastpkt_leap = msg.m_status; + p->lastpkt_rootdelay = sfp_to_d(msg.m_rootdelay); + p->lastpkt_rootdisp = sfp_to_d(msg.m_rootdisp); + p->lastpkt_refid = msg.m_refid; + + /* + * From RFC 2030 (with a correction to the delay math): + * + * Timestamp Name ID When Generated + * ------------------------------------------------------------ + * Originate Timestamp T1 time request sent by client + * Receive Timestamp T2 time request received by server + * Transmit Timestamp T3 time reply sent by server + * Destination Timestamp T4 time reply received by client + * + * The roundtrip delay and local clock offset are defined as + * + * delay = (T4 - T1) - (T3 - T2); offset = ((T2 - T1) + (T3 - T4)) / 2 + */ + T1 = p->p_xmttime; + T2 = lfp_to_d(msg.m_rectime); + T3 = lfp_to_d(msg.m_xmttime); + T4 = gettime1900d(); + + p->lastpkt_recv_time = T4; + + VERB5 bb_error_msg("%s->lastpkt_recv_time=%f", p->p_dotted, p->lastpkt_recv_time); + p->datapoint_idx = p->p_reachable_bits ? (p->datapoint_idx + 1) % NUM_DATAPOINTS : 0; + datapoint = &p->filter_datapoint[p->datapoint_idx]; + datapoint->d_recv_time = T4; + datapoint->d_offset = ((T2 - T1) + (T3 - T4)) / 2; + /* The delay calculation is a special case. In cases where the + * server and client clocks are running at different rates and + * with very fast networks, the delay can appear negative. In + * order to avoid violating the Principle of Least Astonishment, + * the delay is clamped not less than the system precision. + */ + p->lastpkt_delay = (T4 - T1) - (T3 - T2); + datapoint->d_dispersion = LOG2D(msg.m_precision_exp) + G_precision_sec; + if (!p->p_reachable_bits) { + /* 1st datapoint ever - replicate offset in every element */ + int i; + for (i = 1; i < NUM_DATAPOINTS; i++) { + p->filter_datapoint[i].d_offset = datapoint->d_offset; + } + } + + p->p_reachable_bits |= 1; + VERB1 { + bb_error_msg("reply from %s: reach 0x%02x offset %f delay %f", + p->p_dotted, + p->p_reachable_bits, + datapoint->d_offset, p->lastpkt_delay); + } + + /* Muck with statictics and update the clock */ + filter_datapoints(p, T4); + q = select_and_cluster(T4); + rc = -1; + if (q) + rc = update_local_clock(q, T4); + + if (rc != 0) { + /* Adjust the poll interval by comparing the current offset + * with the clock jitter. If the offset is less than + * the clock jitter times a constant, then the averaging interval + * is increased, otherwise it is decreased. A bit of hysteresis + * helps calm the dance. Works best using burst mode. + */ + VERB4 if (rc > 0) { + bb_error_msg("offset:%f POLLADJ_GATE*discipline_jitter:%f poll:%s", + q->filter_offset, POLLADJ_GATE * G.discipline_jitter, + fabs(q->filter_offset) < POLLADJ_GATE * G.discipline_jitter + ? "grows" : "falls" + ); + } + if (rc > 0 && fabs(q->filter_offset) < POLLADJ_GATE * G.discipline_jitter) { + G.polladj_count += G.poll_exp; + if (G.polladj_count > POLLADJ_LIMIT) { + G.polladj_count = 0; + if (G.poll_exp < MAXPOLL) { + G.poll_exp++; + VERB3 bb_error_msg("polladj: discipline_jitter:%f ++poll_exp=%d", + G.discipline_jitter, G.poll_exp); + } + } else { + VERB3 bb_error_msg("polladj: incr:%d", G.polladj_count); + } + } else { + G.polladj_count -= G.poll_exp * 2; + if (G.polladj_count < -POLLADJ_LIMIT) { + G.polladj_count = 0; + if (G.poll_exp > MINPOLL) { + G.poll_exp--; + VERB3 bb_error_msg("polladj: discipline_jitter:%f --poll_exp=%d", + G.discipline_jitter, G.poll_exp); + } + } else { + VERB3 bb_error_msg("polladj: decr:%d", G.polladj_count); + } + } + } + + /* Decide when to send new query for this peer */ + interval = poll_interval(0); + set_next(p, interval); + + close_sock: + /* We do not expect any more packets from this peer for now. + * Closing the socket informs kernel about it. + * We open a new socket when we send a new query. + */ + close(p->p_fd); + p->p_fd = -1; + bail: + return; +} + +#if ENABLE_FEATURE_NTPD_SERVER +static void +recv_and_process_client_pkt(void /*int fd*/) +{ + ssize_t size; + uint8_t version; + double rectime; + len_and_sockaddr *to; + struct sockaddr *from; + msg_t msg; + uint8_t query_status; + l_fixedpt_t query_xmttime; + + to = get_sock_lsa(G.listen_fd); + from = xzalloc(to->len); + + size = recv_from_to(G.listen_fd, &msg, sizeof(msg), MSG_DONTWAIT, from, &to->u.sa, to->len); + if (size != NTP_MSGSIZE_NOAUTH && size != NTP_MSGSIZE) { + char *addr; + if (size < 0) { + if (errno == EAGAIN) + goto bail; + bb_perror_msg_and_die("recv"); + } + addr = xmalloc_sockaddr2dotted_noport(from); + bb_error_msg("malformed packet received from %s: size %u", addr, (int)size); + free(addr); + goto bail; + } + + query_status = msg.m_status; + query_xmttime = msg.m_xmttime; + + /* Build a reply packet */ + memset(&msg, 0, sizeof(msg)); + msg.m_status = G.stratum < MAXSTRAT ? G.leap : LI_ALARM; + msg.m_status |= (query_status & VERSION_MASK); + msg.m_status |= ((query_status & MODE_MASK) == MODE_CLIENT) ? + MODE_SERVER : MODE_SYM_PAS; + msg.m_stratum = G.stratum; + msg.m_ppoll = G.poll_exp; + msg.m_precision_exp = G_precision_exp; + rectime = gettime1900d(); + msg.m_xmttime = msg.m_rectime = d_to_lfp(rectime); + msg.m_reftime = d_to_lfp(G.reftime); + msg.m_orgtime = query_xmttime; + msg.m_rootdelay = d_to_sfp(G.rootdelay); +//simple code does not do this, fix simple code! + msg.m_rootdisp = d_to_sfp(G.rootdisp); + version = (query_status & VERSION_MASK); /* ... >> VERSION_SHIFT - done below instead */ + msg.m_refid = G.refid; // (version > (3 << VERSION_SHIFT)) ? G.refid : G.refid3; + + /* We reply from the local address packet was sent to, + * this makes to/from look swapped here: */ + do_sendto(G.listen_fd, + /*from:*/ &to->u.sa, /*to:*/ from, /*addrlen:*/ to->len, + &msg, size); + + bail: + free(to); + free(from); +} +#endif + +/* Upstream ntpd's options: + * + * -4 Force DNS resolution of host names to the IPv4 namespace. + * -6 Force DNS resolution of host names to the IPv6 namespace. + * -a Require cryptographic authentication for broadcast client, + * multicast client and symmetric passive associations. + * This is the default. + * -A Do not require cryptographic authentication for broadcast client, + * multicast client and symmetric passive associations. + * This is almost never a good idea. + * -b Enable the client to synchronize to broadcast servers. + * -c conffile + * Specify the name and path of the configuration file, + * default /etc/ntp.conf + * -d Specify debugging mode. This option may occur more than once, + * with each occurrence indicating greater detail of display. + * -D level + * Specify debugging level directly. + * -f driftfile + * Specify the name and path of the frequency file. + * This is the same operation as the "driftfile FILE" + * configuration command. + * -g Normally, ntpd exits with a message to the system log + * if the offset exceeds the panic threshold, which is 1000 s + * by default. This option allows the time to be set to any value + * without restriction; however, this can happen only once. + * If the threshold is exceeded after that, ntpd will exit + * with a message to the system log. This option can be used + * with the -q and -x options. See the tinker command for other options. + * -i jaildir + * Chroot the server to the directory jaildir. This option also implies + * that the server attempts to drop root privileges at startup + * (otherwise, chroot gives very little additional security). + * You may need to also specify a -u option. + * -k keyfile + * Specify the name and path of the symmetric key file, + * default /etc/ntp/keys. This is the same operation + * as the "keys FILE" configuration command. + * -l logfile + * Specify the name and path of the log file. The default + * is the system log file. This is the same operation as + * the "logfile FILE" configuration command. + * -L Do not listen to virtual IPs. The default is to listen. + * -n Don't fork. + * -N To the extent permitted by the operating system, + * run the ntpd at the highest priority. + * -p pidfile + * Specify the name and path of the file used to record the ntpd + * process ID. This is the same operation as the "pidfile FILE" + * configuration command. + * -P priority + * To the extent permitted by the operating system, + * run the ntpd at the specified priority. + * -q Exit the ntpd just after the first time the clock is set. + * This behavior mimics that of the ntpdate program, which is + * to be retired. The -g and -x options can be used with this option. + * Note: The kernel time discipline is disabled with this option. + * -r broadcastdelay + * Specify the default propagation delay from the broadcast/multicast + * server to this client. This is necessary only if the delay + * cannot be computed automatically by the protocol. + * -s statsdir + * Specify the directory path for files created by the statistics + * facility. This is the same operation as the "statsdir DIR" + * configuration command. + * -t key + * Add a key number to the trusted key list. This option can occur + * more than once. + * -u user[:group] + * Specify a user, and optionally a group, to switch to. + * -v variable + * -V variable + * Add a system variable listed by default. + * -x Normally, the time is slewed if the offset is less than the step + * threshold, which is 128 ms by default, and stepped if above + * the threshold. This option sets the threshold to 600 s, which is + * well within the accuracy window to set the clock manually. + * Note: since the slew rate of typical Unix kernels is limited + * to 0.5 ms/s, each second of adjustment requires an amortization + * interval of 2000 s. Thus, an adjustment as much as 600 s + * will take almost 14 days to complete. This option can be used + * with the -g and -q options. See the tinker command for other options. + * Note: The kernel time discipline is disabled with this option. + */ + +/* By doing init in a separate function we decrease stack usage + * in main loop. + */ +static NOINLINE void ntp_init(char **argv) +{ + unsigned opts; + llist_t *peers; + + srandom(getpid()); + + if (getuid()) + bb_error_msg_and_die(bb_msg_you_must_be_root); + + /* Set some globals */ +#if 0 + /* With constant b = 100, G.precision_exp is also constant -6. + * Uncomment this to verify. + */ + { + int prec = 0; + int b; +# if 0 + struct timespec tp; + /* We can use sys_clock_getres but assuming 10ms tick should be fine */ + clock_getres(CLOCK_REALTIME, &tp); + tp.tv_sec = 0; + tp.tv_nsec = 10000000; + b = 1000000000 / tp.tv_nsec; /* convert to Hz */ +# else + b = 100; /* b = 1000000000/10000000 = 100 */ +# endif + while (b > 1) + prec--, b >>= 1; + /*G.precision_exp = prec;*/ + /*G.precision_sec = (1.0 / (1 << (- prec)));*/ + bb_error_msg("G.precision_exp:%d sec:%f", prec, G_precision_sec); /* -6 */ + } +#endif + G.stratum = MAXSTRAT; + G.poll_exp = 1; /* should use MINPOLL, but 1 speeds up initial sync */ + G.reftime = G.last_update_recv_time = gettime1900d(); + + /* Parse options */ + peers = NULL; + opt_complementary = "dd:p::"; /* d: counter, p: list */ + opts = getopt32(argv, + "nqNx" /* compat */ + "p:"IF_FEATURE_NTPD_SERVER("l") /* NOT compat */ + "d" /* compat */ + "46aAbgL", /* compat, ignored */ + &peers, &G.verbose); + if (!(opts & (OPT_p|OPT_l))) + bb_show_usage(); +// if (opts & OPT_x) /* disable stepping, only slew is allowed */ +// G.time_was_stepped = 1; + while (peers) + add_peers(llist_pop(&peers)); + if (!(opts & OPT_n)) { + bb_daemonize_or_rexec(DAEMON_DEVNULL_STDIO, argv); + logmode = LOGMODE_NONE; + } +#if ENABLE_FEATURE_NTPD_SERVER + G.listen_fd = -1; + if (opts & OPT_l) { + G.listen_fd = create_and_bind_dgram_or_die(NULL, 123); + socket_want_pktinfo(G.listen_fd); + setsockopt(G.listen_fd, IPPROTO_IP, IP_TOS, &const_IPTOS_LOWDELAY, sizeof(const_IPTOS_LOWDELAY)); + } +#endif + /* I hesitate to set -20 prio. -15 should be high enough for timekeeping */ + if (opts & OPT_N) + setpriority(PRIO_PROCESS, 0, -15); + + bb_signals((1 << SIGTERM) | (1 << SIGINT), record_signo); + bb_signals((1 << SIGPIPE) | (1 << SIGHUP), SIG_IGN); +} + +int ntpd_main(int argc UNUSED_PARAM, char **argv) MAIN_EXTERNALLY_VISIBLE; +int ntpd_main(int argc UNUSED_PARAM, char **argv) +{ + struct globals g; + struct pollfd *pfd; + peer_t **idx2peer; + + memset(&g, 0, sizeof(g)); + SET_PTR_TO_GLOBALS(&g); + + ntp_init(argv); + + { + /* if ENABLE_FEATURE_NTPD_SERVER, + 1 for listen_fd: */ + unsigned cnt = g.peer_cnt + ENABLE_FEATURE_NTPD_SERVER; + idx2peer = xzalloc(sizeof(idx2peer[0]) * cnt); + pfd = xzalloc(sizeof(pfd[0]) * cnt); + } + + while (!bb_got_signal) { + llist_t *item; + unsigned i, j; + unsigned sent_cnt, trial_cnt; + int nfds, timeout; + time_t cur_time, nextaction; + + /* Nothing between here and poll() blocks for any significant time */ + + cur_time = time(NULL); + nextaction = cur_time + 3600; + + i = 0; +#if ENABLE_FEATURE_NTPD_SERVER + if (g.listen_fd != -1) { + pfd[0].fd = g.listen_fd; + pfd[0].events = POLLIN; + i++; + } +#endif + /* Pass over peer list, send requests, time out on receives */ + sent_cnt = trial_cnt = 0; + for (item = g.ntp_peers; item != NULL; item = item->link) { + peer_t *p = (peer_t *) item->data; + + /* Overflow-safe "if (p->next_action_time <= cur_time) ..." */ + if ((int)(cur_time - p->next_action_time) >= 0) { + if (p->p_fd == -1) { + /* Time to send new req */ + trial_cnt++; + if (send_query_to_peer(p) == 0) + sent_cnt++; + } else { + /* Timed out waiting for reply */ + close(p->p_fd); + p->p_fd = -1; + timeout = poll_interval(-1); /* try a bit faster */ + bb_error_msg("timed out waiting for %s, reach 0x%02x, next query in %us", + p->p_dotted, p->p_reachable_bits, timeout); + set_next(p, timeout); + } + } + + if (p->next_action_time < nextaction) + nextaction = p->next_action_time; + + if (p->p_fd >= 0) { + /* Wait for reply from this peer */ + pfd[i].fd = p->p_fd; + pfd[i].events = POLLIN; + idx2peer[i] = p; + i++; + } + } + +// if ((trial_cnt > 0 && sent_cnt == 0) || g.peer_cnt == 0) { +// G.time_was_stepped = 1; +// } + + timeout = nextaction - cur_time; + if (timeout < 1) + timeout = 1; + + /* Here we may block */ + VERB2 bb_error_msg("poll %us, sockets:%u", timeout, i); + nfds = poll(pfd, i, timeout * 1000); + if (nfds <= 0) + continue; + + /* Process any received packets */ + j = 0; +#if ENABLE_FEATURE_NTPD_SERVER + if (g.listen_fd != -1) { + if (pfd[0].revents /* & (POLLIN|POLLERR)*/) { + nfds--; + recv_and_process_client_pkt(/*g.listen_fd*/); + } + j = 1; + } +#endif + for (; nfds != 0 && j < i; j++) { + if (pfd[j].revents /* & (POLLIN|POLLERR)*/) { + nfds--; + recv_and_process_peer_pkt(idx2peer[j]); + } + } + } /* while (!bb_got_signal) */ + + kill_myself_with_sig(bb_got_signal); +} + + + + + + +/*** openntpd-4.6 uses only adjtime, not adjtimex ***/ + +/*** ntp-4.2.6/ntpd/ntp_loopfilter.c - adjtimex usage ***/ + +#if 0 +static double +direct_freq(double fp_offset) +{ + +#ifdef KERNEL_PLL + /* + * If the kernel is enabled, we need the residual offset to + * calculate the frequency correction. + */ + if (pll_control && kern_enable) { + memset(&ntv, 0, sizeof(ntv)); + ntp_adjtime(&ntv); +#ifdef STA_NANO + clock_offset = ntv.offset / 1e9; +#else /* STA_NANO */ + clock_offset = ntv.offset / 1e6; +#endif /* STA_NANO */ + drift_comp = FREQTOD(ntv.freq); + } +#endif /* KERNEL_PLL */ + set_freq((fp_offset - clock_offset) / (current_time - clock_epoch) + drift_comp); + wander_resid = 0; + return drift_comp; +} + +static void +set_freq(double freq) /* frequency update */ +{ + char tbuf[80]; + + drift_comp = freq; + +#ifdef KERNEL_PLL + /* + * If the kernel is enabled, update the kernel frequency. + */ + if (pll_control && kern_enable) { + memset(&ntv, 0, sizeof(ntv)); + ntv.modes = MOD_FREQUENCY; + ntv.freq = DTOFREQ(drift_comp); + ntp_adjtime(&ntv); + snprintf(tbuf, sizeof(tbuf), "kernel %.3f PPM", drift_comp * 1e6); + report_event(EVNT_FSET, NULL, tbuf); + } else { + snprintf(tbuf, sizeof(tbuf), "ntpd %.3f PPM", drift_comp * 1e6); + report_event(EVNT_FSET, NULL, tbuf); + } +#else /* KERNEL_PLL */ + snprintf(tbuf, sizeof(tbuf), "ntpd %.3f PPM", drift_comp * 1e6); + report_event(EVNT_FSET, NULL, tbuf); +#endif /* KERNEL_PLL */ +} + +... +... +... + +#ifdef KERNEL_PLL + /* + * This code segment works when clock adjustments are made using + * precision time kernel support and the ntp_adjtime() system + * call. This support is available in Solaris 2.6 and later, + * Digital Unix 4.0 and later, FreeBSD, Linux and specially + * modified kernels for HP-UX 9 and Ultrix 4. In the case of the + * DECstation 5000/240 and Alpha AXP, additional kernel + * modifications provide a true microsecond clock and nanosecond + * clock, respectively. + * + * Important note: The kernel discipline is used only if the + * step threshold is less than 0.5 s, as anything higher can + * lead to overflow problems. This might occur if some misguided + * lad set the step threshold to something ridiculous. + */ + if (pll_control && kern_enable) { + +#define MOD_BITS (MOD_OFFSET | MOD_MAXERROR | MOD_ESTERROR | MOD_STATUS | MOD_TIMECONST) + + /* + * We initialize the structure for the ntp_adjtime() + * system call. We have to convert everything to + * microseconds or nanoseconds first. Do not update the + * system variables if the ext_enable flag is set. In + * this case, the external clock driver will update the + * variables, which will be read later by the local + * clock driver. Afterwards, remember the time and + * frequency offsets for jitter and stability values and + * to update the frequency file. + */ + memset(&ntv, 0, sizeof(ntv)); + if (ext_enable) { + ntv.modes = MOD_STATUS; + } else { +#ifdef STA_NANO + ntv.modes = MOD_BITS | MOD_NANO; +#else /* STA_NANO */ + ntv.modes = MOD_BITS; +#endif /* STA_NANO */ + if (clock_offset < 0) + dtemp = -.5; + else + dtemp = .5; +#ifdef STA_NANO + ntv.offset = (int32)(clock_offset * 1e9 + dtemp); + ntv.constant = sys_poll; +#else /* STA_NANO */ + ntv.offset = (int32)(clock_offset * 1e6 + dtemp); + ntv.constant = sys_poll - 4; +#endif /* STA_NANO */ + ntv.esterror = (u_int32)(clock_jitter * 1e6); + ntv.maxerror = (u_int32)((sys_rootdelay / 2 + sys_rootdisp) * 1e6); + ntv.status = STA_PLL; + + /* + * Enable/disable the PPS if requested. + */ + if (pps_enable) { + if (!(pll_status & STA_PPSTIME)) + report_event(EVNT_KERN, + NULL, "PPS enabled"); + ntv.status |= STA_PPSTIME | STA_PPSFREQ; + } else { + if (pll_status & STA_PPSTIME) + report_event(EVNT_KERN, + NULL, "PPS disabled"); + ntv.status &= ~(STA_PPSTIME | + STA_PPSFREQ); + } + if (sys_leap == LEAP_ADDSECOND) + ntv.status |= STA_INS; + else if (sys_leap == LEAP_DELSECOND) + ntv.status |= STA_DEL; + } + + /* + * Pass the stuff to the kernel. If it squeals, turn off + * the pps. In any case, fetch the kernel offset, + * frequency and jitter. + */ + if (ntp_adjtime(&ntv) == TIME_ERROR) { + if (!(ntv.status & STA_PPSSIGNAL)) + report_event(EVNT_KERN, NULL, + "PPS no signal"); + } + pll_status = ntv.status; +#ifdef STA_NANO + clock_offset = ntv.offset / 1e9; +#else /* STA_NANO */ + clock_offset = ntv.offset / 1e6; +#endif /* STA_NANO */ + clock_frequency = FREQTOD(ntv.freq); + + /* + * If the kernel PPS is lit, monitor its performance. + */ + if (ntv.status & STA_PPSTIME) { +#ifdef STA_NANO + clock_jitter = ntv.jitter / 1e9; +#else /* STA_NANO */ + clock_jitter = ntv.jitter / 1e6; +#endif /* STA_NANO */ + } + +#if defined(STA_NANO) && NTP_API == 4 + /* + * If the TAI changes, update the kernel TAI. + */ + if (loop_tai != sys_tai) { + loop_tai = sys_tai; + ntv.modes = MOD_TAI; + ntv.constant = sys_tai; + ntp_adjtime(&ntv); + } +#endif /* STA_NANO */ + } +#endif /* KERNEL_PLL */ +#endif |