diff options
Diffstat (limited to 'networking/ntpd_simple.c')
| -rw-r--r-- | networking/ntpd_simple.c | 1007 |
1 files changed, 1007 insertions, 0 deletions
diff --git a/networking/ntpd_simple.c b/networking/ntpd_simple.c new file mode 100644 index 0000000..5e48306 --- /dev/null +++ b/networking/ntpd_simple.c @@ -0,0 +1,1007 @@ +/* + * 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. + */ +#include "libbb.h" +#include <netinet/ip.h> /* For IPTOS_LOWDELAY definition */ +#ifndef IPTOS_LOWDELAY +# define IPTOS_LOWDELAY 0x10 +#endif +#ifndef IP_PKTINFO +# error "Sorry, your kernel has to support IP_PKTINFO" +#endif + + +/* Sync to peers every N secs */ +#define INTERVAL_QUERY_NORMAL 30 +#define INTERVAL_QUERY_PATHETIC 60 +#define INTERVAL_QUERY_AGRESSIVE 5 + +/* Bad if *less than* TRUSTLEVEL_BADPEER */ +#define TRUSTLEVEL_BADPEER 6 +#define TRUSTLEVEL_PATHETIC 2 +#define TRUSTLEVEL_AGRESSIVE 8 +#define TRUSTLEVEL_MAX 10 + +#define QSCALE_OFF_MIN 0.05 +#define QSCALE_OFF_MAX 0.50 + +/* Single query might take N secs max */ +#define QUERYTIME_MAX 15 +/* Min offset for settime at start. "man ntpd" says it's 128 ms */ +#define STEPTIME_MIN_OFFSET 0.128 + +typedef struct { + uint32_t int_partl; + uint32_t fractionl; +} l_fixedpt_t; + +typedef struct { + uint16_t int_parts; + uint16_t fractions; +} s_fixedpt_t; + +enum { + NTP_DIGESTSIZE = 16, + NTP_MSGSIZE_NOAUTH = 48, + NTP_MSGSIZE = (NTP_MSGSIZE_NOAUTH + 4 + NTP_DIGESTSIZE), +}; + +typedef struct { + uint8_t m_status; /* status of local clock and leap info */ + uint8_t m_stratum; /* stratum level */ + uint8_t m_ppoll; /* poll value */ + int8_t m_precision_exp; + s_fixedpt_t m_rootdelay; + s_fixedpt_t m_dispersion; + 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; + +enum { + NTP_VERSION = 4, + NTP_MAXSTRATUM = 15, + + /* 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 */ +}; + +#define OFFSET_1900_1970 2208988800UL /* 1970 - 1900 in seconds */ + +typedef struct { + double d_offset; + double d_delay; + //UNUSED: double d_error; + time_t d_rcv_time; + uint32_t d_refid4; + uint8_t d_leap; + uint8_t d_stratum; + uint8_t d_good; +} datapoint_t; + +#define NUM_DATAPOINTS 8 +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; + uint8_t p_datapoint_idx; + uint8_t p_trustlevel; + double p_xmttime; + datapoint_t update; + datapoint_t p_datapoint[NUM_DATAPOINTS]; + 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; + llist_t *ntp_peers; +#if ENABLE_FEATURE_NTPD_SERVER + int listen_fd; +#endif + unsigned verbose; + unsigned peer_cnt; + unsigned scale; + uint32_t refid; + uint32_t refid4; + uint8_t synced; + uint8_t leap; +#define G_precision_exp -6 +// int8_t precision_exp; + uint8_t stratum; + uint8_t time_was_stepped; + uint8_t first_adj_done; +}; +#define G (*ptr_to_globals) + +static const int const_IPTOS_LOWDELAY = IPTOS_LOWDELAY; + + +static void +set_next(peer_t *p, unsigned t) +{ + p->next_action_time = time(NULL) + t; +} + +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->p_trustlevel = TRUSTLEVEL_PATHETIC; + p->next_action_time = time(NULL); /* = set_next(p, 0); */ + + llist_add_to(&G.ntp_peers, p); + G.peer_cnt++; +} + +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; +} + +#if 0 //UNUSED +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; +} +#endif + +#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 unsigned +error_interval(void) +{ + unsigned interval, r; + interval = INTERVAL_QUERY_PATHETIC * QSCALE_OFF_MAX / QSCALE_OFF_MIN; + r = (unsigned)random() % (unsigned)(interval / 10); + return (interval + r); +} + +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, INTERVAL_QUERY_PATHETIC); + return -1; + } + + if (G.verbose) + bb_error_msg("sent query to %s", p->p_dotted); + set_next(p, QUERYTIME_MAX); + + return 0; +} + + +/* Time is stepped only once, when the first packet from a peer is received. + */ +static void +step_time_once(double offset) +{ + double dtime; + llist_t *item; + struct timeval tv; + char buf[80]; + time_t tval; + + if (G.time_was_stepped) + goto bail; + G.time_was_stepped = 1; + + /* if the offset is small, don't step, slew (later) */ + if (offset < STEPTIME_MIN_OFFSET && offset > -STEPTIME_MIN_OFFSET) + goto bail; + + 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); + + for (item = G.ntp_peers; item != NULL; item = item->link) { + peer_t *p = (peer_t *) item->data; + p->next_action_time -= (time_t)offset; + } + + bail: + if (option_mask32 & OPT_q) + exit(0); +} + + +/* Time is periodically slewed when we collect enough + * good data points. + */ +static int +compare_offsets(const void *aa, const void *bb) +{ + const peer_t *const *a = aa; + const peer_t *const *b = bb; + if ((*a)->update.d_offset < (*b)->update.d_offset) + return -1; + return ((*a)->update.d_offset > (*b)->update.d_offset); +} +static unsigned +updated_scale(double offset) +{ + if (offset < 0) + offset = -offset; + if (offset > QSCALE_OFF_MAX) + return 1; + if (offset < QSCALE_OFF_MIN) + return QSCALE_OFF_MAX / QSCALE_OFF_MIN; + return QSCALE_OFF_MAX / offset; +} +static void +slew_time(void) +{ + llist_t *item; + double offset_median; + struct timeval tv; + + { + peer_t **peers = xzalloc(sizeof(peers[0]) * G.peer_cnt); + unsigned goodpeer_cnt = 0; + unsigned middle; + + for (item = G.ntp_peers; item != NULL; item = item->link) { + peer_t *p = (peer_t *) item->data; + if (p->p_trustlevel < TRUSTLEVEL_BADPEER) + continue; + if (!p->update.d_good) { + free(peers); + return; + } + peers[goodpeer_cnt++] = p; + } + + if (goodpeer_cnt == 0) { + free(peers); + goto clear_good; + } + + qsort(peers, goodpeer_cnt, sizeof(peers[0]), compare_offsets); + + middle = goodpeer_cnt / 2; + if (middle != 0 && (goodpeer_cnt & 1) == 0) { + offset_median = (peers[middle-1]->update.d_offset + peers[middle]->update.d_offset) / 2; + G.rootdelay = (peers[middle-1]->update.d_delay + peers[middle]->update.d_delay) / 2; + G.stratum = 1 + MAX(peers[middle-1]->update.d_stratum, peers[middle]->update.d_stratum); + } else { + offset_median = peers[middle]->update.d_offset; + G.rootdelay = peers[middle]->update.d_delay; + G.stratum = 1 + peers[middle]->update.d_stratum; + } + G.leap = peers[middle]->update.d_leap; + G.refid4 = peers[middle]->update.d_refid4; + G.refid = +#if ENABLE_FEATURE_IPV6 + peers[middle]->p_lsa->u.sa.sa_family != AF_INET ? + G.refid4 : +#endif + peers[middle]->p_lsa->u.sin.sin_addr.s_addr; + free(peers); + } +//TODO: if (offset_median > BIG) step_time(offset_median)? + + G.scale = updated_scale(offset_median); + + bb_error_msg("adjusting clock by %fs, our stratum is %u, time scale %u", + offset_median, G.stratum, G.scale); + + errno = 0; + d_to_tv(offset_median, &tv); + if (adjtime(&tv, &tv) == -1) + bb_perror_msg_and_die("adjtime failed"); + if (G.verbose >= 2) + bb_error_msg("old adjust: %d.%06u", (int)tv.tv_sec, (unsigned)tv.tv_usec); + + if (G.first_adj_done) { + uint8_t synced = (tv.tv_sec == 0 && tv.tv_usec == 0); + if (synced != G.synced) { + G.synced = synced; + bb_error_msg("clock is %ssynced", synced ? "" : "un"); + } + } + G.first_adj_done = 1; + + G.reftime = gettime1900d(); + + clear_good: + for (item = G.ntp_peers; item != NULL; item = item->link) { + peer_t *p = (peer_t *) item->data; + p->update.d_good = 0; + } +} + +static void +update_peer_data(peer_t *p) +{ + /* Clock filter. + * Find the datapoint with the lowest delay. + * Use that as the peer update. + * Invalidate it and all older ones. + */ + int i; + int best = -1; + int good = 0; + + for (i = 0; i < NUM_DATAPOINTS; i++) { + if (p->p_datapoint[i].d_good) { + good++; + if (best < 0 || p->p_datapoint[i].d_delay < p->p_datapoint[best].d_delay) + best = i; + } + } + + if (good < 8) //FIXME: was it meant to be NUM_DATAPOINTS, not 8? + return; + + p->update = p->p_datapoint[best]; /* struct copy */ + slew_time(); + + for (i = 0; i < NUM_DATAPOINTS; i++) + if (p->p_datapoint[i].d_rcv_time <= p->p_datapoint[best].d_rcv_time) + p->p_datapoint[i].d_good = 0; +} + +static unsigned +scale_interval(unsigned requested) +{ + unsigned interval, r; + interval = requested * G.scale; + r = (unsigned)random() % (unsigned)(MAX(5, interval / 10)); + return (interval + r); +} +static void +recv_and_process_peer_pkt(peer_t *p) +{ + ssize_t size; + msg_t msg; + double T1, T2, T3, T4; + unsigned interval; + datapoint_t *datapoint; + + /* 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, error_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 = error_interval(); + bb_error_msg("reply from %s: not synced, next query in %us", p->p_dotted, interval); + goto close_sock; + } + + /* + * 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(); + + datapoint = &p->p_datapoint[p->p_datapoint_idx]; + + datapoint->d_offset = ((T2 - T1) + (T3 - T4)) / 2; + datapoint->d_delay = (T4 - T1) - (T3 - T2); + if (datapoint->d_delay < 0) { + bb_error_msg("reply from %s: negative delay %f", p->p_dotted, datapoint->d_delay); + interval = error_interval(); + set_next(p, interval); + goto close_sock; + } + //UNUSED: datapoint->d_error = (T2 - T1) - (T3 - T4); + datapoint->d_rcv_time = (time_t)(T4 - OFFSET_1900_1970); /* = time(NULL); */ + datapoint->d_good = 1; + + datapoint->d_leap = (msg.m_status & LI_MASK); + //UNUSED: datapoint->o_precision = msg.m_precision_exp; + //UNUSED: datapoint->o_rootdelay = sfp_to_d(msg.m_rootdelay); + //UNUSED: datapoint->o_rootdispersion = sfp_to_d(msg.m_dispersion); + //UNUSED: datapoint->d_refid = ntohl(msg.m_refid); + datapoint->d_refid4 = msg.m_xmttime.fractionl; + //UNUSED: datapoint->o_reftime = lfp_to_d(msg.m_reftime); + //UNUSED: datapoint->o_poll = msg.m_ppoll; + datapoint->d_stratum = msg.m_stratum; + + if (p->p_trustlevel < TRUSTLEVEL_PATHETIC) + interval = scale_interval(INTERVAL_QUERY_PATHETIC); + else if (p->p_trustlevel < TRUSTLEVEL_AGRESSIVE) + interval = scale_interval(INTERVAL_QUERY_AGRESSIVE); + else + interval = scale_interval(INTERVAL_QUERY_NORMAL); + + set_next(p, interval); + + /* Every received reply which we do not discard increases trust */ + if (p->p_trustlevel < TRUSTLEVEL_MAX) { + p->p_trustlevel++; + if (p->p_trustlevel == TRUSTLEVEL_BADPEER) + bb_error_msg("peer %s now valid", p->p_dotted); + } + + if (G.verbose) + bb_error_msg("reply from %s: offset %f delay %f, next query in %us", p->p_dotted, + datapoint->d_offset, datapoint->d_delay, interval); + + update_peer_data(p); +//TODO: do it after all peers had a chance to return at least one reply? + step_time_once(datapoint->d_offset); + + p->p_datapoint_idx++; + if (p->p_datapoint_idx >= NUM_DATAPOINTS) + p->p_datapoint_idx = 0; + + 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; + uint8_t query_ppoll; + 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_ppoll = msg.m_ppoll; + query_xmttime = msg.m_xmttime; + + /* Build a reply packet */ + memset(&msg, 0, sizeof(msg)); + msg.m_status = G.synced ? 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 = query_ppoll; + 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_xmttime = d_to_lfp(gettime1900d()); // = msg.m_rectime + msg.m_orgtime = query_xmttime; + msg.m_rootdelay = d_to_sfp(G.rootdelay); + version = (query_status & VERSION_MASK); /* ... >> VERSION_SHIFT - done below instead */ + msg.m_refid = (version > (3 << VERSION_SHIFT)) ? G.refid4 : G.refid; + + /* 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); + + 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); + + /* Set some globals */ +#if 0 + /* With constant b = 100, G.precision_exp is also constant -6. + * Uncomment this and you'll see */ + { + 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; + bb_error_msg("G.precision_exp:%d", prec); /* -6 */ + } +#endif + G.scale = 1; + + 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 = error_interval(); + bb_error_msg("timed out waiting for %s, " + "next query in %us", p->p_dotted, timeout); + if (p->p_trustlevel >= TRUSTLEVEL_BADPEER) { + p->p_trustlevel /= 2; + if (p->p_trustlevel < TRUSTLEVEL_BADPEER) + bb_error_msg("peer %s now invalid", p->p_dotted); + } + 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) + step_time_once(0); /* no good peers, don't wait */ + + timeout = nextaction - cur_time; + if (timeout < 1) + timeout = 1; + + /* Here we may block */ + if (g.verbose >= 2) + 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); +} |