/* * NTP client/server, based on OpenNTPD 3.9p1 * * Author: Adam Tkac * * Licensed under GPLv2, see file LICENSE in this tarball for details. */ #include "libbb.h" #include /* 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 #define INTERVAL_QUERY_NORMAL 30 /* sync to peers every n secs */ #define INTERVAL_QUERY_PATHETIC 60 #define INTERVAL_QUERY_AGRESSIVE 5 #define TRUSTLEVEL_BADPEER 6 /* bad if *less than* TRUSTLEVEL_BADPEER */ #define TRUSTLEVEL_PATHETIC 2 #define TRUSTLEVEL_AGRESSIVE 8 #define TRUSTLEVEL_MAX 10 #define QSCALE_OFF_MIN 0.05 #define QSCALE_OFF_MAX 0.50 #define QUERYTIME_MAX 15 /* single query might take n secs max */ #define OFFSET_ARRAY_SIZE 8 #define SETTIME_MIN_OFFSET 180 /* min offset for settime at start */ #define SETTIME_TIMEOUT 15 /* max seconds to wait with -s */ /* Style borrowed from NTP ref/tcpdump and updated for SNTPv4 (RFC2030). */ /* * RFC Section 3 * * 0 1 2 3 * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ * | Integer Part | * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ * | Fraction Part | * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ * * 0 1 2 3 * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ * | Integer Part | Fraction Part | * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ */ 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 status; /* status of local clock and leap info */ uint8_t stratum; /* stratum level */ uint8_t ppoll; /* poll value */ int8_t precision; s_fixedpt_t rootdelay; s_fixedpt_t dispersion; uint32_t refid; l_fixedpt_t reftime; l_fixedpt_t orgtime; l_fixedpt_t rectime; l_fixedpt_t xmttime; uint32_t keyid; uint8_t digest[NTP_DIGESTSIZE]; } ntp_msg_t; typedef struct { int fd; ntp_msg_t msg; double xmttime; } ntp_query_t; enum { NTP_VERSION = 4, NTP_MAXSTRATUM = 15, /* Leap Second Codes (high order two bits) */ 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 */ /* Status Masks */ MODE_MASK = (7 << 0), VERSION_MASK = (7 << 3), VERSION_SHIFT = 3, LI_MASK = (3 << 6), /* 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 */ enum client_state { STATE_NONE, STATE_QUERY_SENT, STATE_REPLY_RECEIVED, }; typedef struct { double rootdelay; double rootdispersion; double reftime; uint32_t refid; uint32_t refid4; uint8_t synced; uint8_t leap; int8_t precision; uint8_t poll; uint8_t stratum; } ntp_status_t; typedef struct { ntp_status_t status; double offset; double delay; double error; time_t rcvd; uint8_t good; } ntp_offset_t; typedef struct { //TODO: // (1) store dotted addr str, to avoid constant translations // (2) periodically re-resolve DNS names len_and_sockaddr *lsa; ntp_query_t query; ntp_offset_t reply[OFFSET_ARRAY_SIZE]; ntp_offset_t update; enum client_state state; time_t next; time_t deadline; uint8_t shift; uint8_t trustlevel; } ntp_peer_t; enum { OPT_n = (1 << 0), OPT_g = (1 << 1), OPT_q = (1 << 2), OPT_N = (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 { unsigned verbose; #if ENABLE_FEATURE_NTPD_SERVER int listen_fd; #endif unsigned peer_cnt; llist_t *ntp_peers; ntp_status_t status; uint32_t scale; uint8_t settime; uint8_t firstadj; }; #define G (*ptr_to_globals) static const int const_IPTOS_LOWDELAY = IPTOS_LOWDELAY; static void set_next(ntp_peer_t *p, time_t t) { p->next = time(NULL) + t; p->deadline = 0; } static void add_peers(const char *s) { ntp_peer_t *p; p = xzalloc(sizeof(*p)); //TODO: big ntpd uses all IPs, not just 1st, do we need to mimic that? p->lsa = xhost2sockaddr(s, 123); p->query.fd = -1; p->query.msg.status = MODE_CLIENT | (NTP_VERSION << 3); if (STATE_NONE != 0) p->state = STATE_NONE; p->trustlevel = TRUSTLEVEL_PATHETIC; p->query.fd = -1; set_next(p, 0); llist_add_to(&G.ntp_peers, p); G.peer_cnt++; } static double gettime1900fp(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 void set_deadline(ntp_peer_t *p, time_t t) { p->deadline = time(NULL) + t; p->next = 0; } static time_t error_interval(void) { time_t interval, r; interval = INTERVAL_QUERY_PATHETIC * QSCALE_OFF_MAX / QSCALE_OFF_MIN; r = (unsigned)random() % (unsigned long)(interval / 10); return (interval + r); } static int sendmsg_wrap(int fd, const struct sockaddr *from, const struct sockaddr *to, socklen_t addrlen, ntp_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(ntp_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->query.fd == -1) { int fd, family; len_and_sockaddr *local_lsa; family = p->lsa->u.sa.sa_family; //was: p->query.fd = xsocket(family, SOCK_DGRAM, 0); p->query.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->query.fd, thus later recv(p->query.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->query.msg.xmttime.int_partl = random(); p->query.msg.xmttime.fractionl = random(); p->query.xmttime = gettime1900fp(); if (sendmsg_wrap(p->query.fd, /*from:*/ NULL, /*to:*/ &p->lsa->u.sa, /*addrlen:*/ p->lsa->len, &p->query.msg, NTP_MSGSIZE_NOAUTH) == -1) { set_next(p, INTERVAL_QUERY_PATHETIC); return -1; } p->state = STATE_QUERY_SENT; set_deadline(p, QUERYTIME_MAX); return 0; } static int offset_compare(const void *aa, const void *bb) { const ntp_peer_t *const *a = aa; const ntp_peer_t *const *b = bb; if ((*a)->update.offset < (*b)->update.offset) return -1; return ((*a)->update.offset > (*b)->update.offset); } static uint32_t 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 adjtime_wrap(void) { ntp_peer_t *p; unsigned offset_cnt; unsigned middle; int i = 0; ntp_peer_t **peers; double offset_median; llist_t *item; len_and_sockaddr *lsa; struct timeval tv, olddelta; offset_cnt = 0; for (item = G.ntp_peers; item != NULL; item = item->link) { p = (ntp_peer_t *) item->data; if (p->trustlevel < TRUSTLEVEL_BADPEER) continue; if (!p->update.good) return; offset_cnt++; } if (offset_cnt == 0) goto clear_good; peers = xzalloc(sizeof(peers[0]) * offset_cnt); for (item = G.ntp_peers; item != NULL; item = item->link) { p = (ntp_peer_t *) item->data; if (p->trustlevel < TRUSTLEVEL_BADPEER) continue; peers[i++] = p; } qsort(peers, offset_cnt, sizeof(peers[0]), offset_compare); middle = offset_cnt / 2; if ((offset_cnt & 1) == 0 && middle != 0) { offset_median = (peers[middle-1]->update.offset + peers[middle]->update.offset) / 2; G.status.rootdelay = (peers[middle-1]->update.delay + peers[middle]->update.delay) / 2; G.status.stratum = MAX(peers[middle-1]->update.status.stratum, peers[middle]->update.status.stratum); } else { offset_median = peers[middle]->update.offset; G.status.rootdelay = peers[middle]->update.delay; G.status.stratum = peers[middle]->update.status.stratum; } G.status.leap = peers[middle]->update.status.leap; bb_info_msg("adjusting local clock by %fs", offset_median); d_to_tv(offset_median, &tv); if (adjtime(&tv, &olddelta) == -1) bb_error_msg("adjtime failed"); else if (!G.firstadj && olddelta.tv_sec == 0 && olddelta.tv_usec == 0 && !G.status.synced ) { bb_info_msg("clock synced"); G.status.synced = 1; } else if (G.status.synced) { bb_info_msg("clock unsynced"); G.status.synced = 0; } G.firstadj = 0; G.status.reftime = gettime1900fp(); G.status.stratum++; /* one more than selected peer */ G.scale = updated_scale(offset_median); G.status.refid4 = peers[middle]->update.status.refid4; lsa = peers[middle]->lsa; G.status.refid = #if ENABLE_FEATURE_IPV6 lsa->u.sa.sa_family != AF_INET ? G.status.refid4 : #endif lsa->u.sin.sin_addr.s_addr; free(peers); clear_good: for (item = G.ntp_peers; item != NULL; item = item->link) { p = (ntp_peer_t *) item->data; p->update.good = 0; } } static void settime(double offset) { ntp_peer_t *p; llist_t *item; struct timeval tv, curtime; char buf[80]; time_t tval; if (!G.settime) goto bail; G.settime = 0; /* if the offset is small, don't call settimeofday */ if (offset < SETTIME_MIN_OFFSET && offset > -SETTIME_MIN_OFFSET) goto bail; gettimeofday(&curtime, NULL); /* never fails */ d_to_tv(offset, &tv); curtime.tv_usec += tv.tv_usec + 1000000; curtime.tv_sec += tv.tv_sec - 1 + (curtime.tv_usec / 1000000); curtime.tv_usec %= 1000000; if (settimeofday(&curtime, NULL) == -1) { bb_error_msg("settimeofday"); goto bail; } tval = curtime.tv_sec; strftime(buf, sizeof(buf), "%a %b %e %H:%M:%S %Z %Y", localtime(&tval)); /* Do we want to print message below to system log when daemonized? */ bb_info_msg("set local clock to %s (offset %fs)", buf, offset); for (item = G.ntp_peers; item != NULL; item = item->link) { p = (ntp_peer_t *) item->data; if (p->next) p->next -= offset; if (p->deadline) p->deadline -= offset; } bail: if (option_mask32 & OPT_q) exit(0); } static void update_peer_data(ntp_peer_t *p) { int i, best = 0, good = 0; /* * clock filter * find the offset which arrived with the lowest delay * use that as the peer update * invalidate it and all older ones */ for (i = 0; good == 0 && i < OFFSET_ARRAY_SIZE; i++) { if (p->reply[i].good) { good++; best = i; } } for (; i < OFFSET_ARRAY_SIZE; i++) { if (p->reply[i].good) { good++; if (p->reply[i].delay < p->reply[best].delay) best = i; } } if (good < 8) return; memcpy(&p->update, &p->reply[best], sizeof(p->update)); adjtime_wrap(); for (i = 0; i < OFFSET_ARRAY_SIZE; i++) if (p->reply[i].rcvd <= p->reply[best].rcvd) p->reply[i].good = 0; } static time_t scale_interval(time_t requested) { time_t interval, r; interval = requested * G.scale; r = (unsigned)random() % (unsigned long)(MAX(5, interval / 10)); return (interval + r); } static void recv_and_process_peer_pkt(ntp_peer_t *p) { char *addr; ssize_t size; ntp_msg_t msg; double T1, T2, T3, T4; time_t interval; ntp_offset_t *offset; addr = xmalloc_sockaddr2dotted_noport(&p->lsa->u.sa); /* 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->query.fd, &msg, sizeof(msg), MSG_DONTWAIT); if (size == -1) { bb_perror_msg("recv(%s) error", addr); 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 bail; } xfunc_die(); } T4 = gettime1900fp(); if (size != NTP_MSGSIZE_NOAUTH && size != NTP_MSGSIZE) { bb_error_msg("malformed packet received from %s", addr); goto bail; } if (msg.orgtime.int_partl != p->query.msg.xmttime.int_partl || msg.orgtime.fractionl != p->query.msg.xmttime.fractionl ) { goto bail; } if ((msg.status & LI_ALARM) == LI_ALARM || msg.stratum == 0 || msg.stratum > NTP_MAXSTRATUM ) { interval = error_interval(); bb_info_msg("reply from %s: not synced, next query %ds", addr, (int) interval); goto bail; } /* * 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 d and local clock offset t are defined as * * d = (T4 - T1) - (T3 - T2) t = ((T2 - T1) + (T3 - T4)) / 2. */ T1 = p->query.xmttime; T2 = lfp_to_d(msg.rectime); T3 = lfp_to_d(msg.xmttime); offset = &p->reply[p->shift]; offset->offset = ((T2 - T1) + (T3 - T4)) / 2; offset->delay = (T4 - T1) - (T3 - T2); if (offset->delay < 0) { interval = error_interval(); set_next(p, interval); bb_info_msg("reply from %s: negative delay %f", addr, p->reply[p->shift].delay); goto bail; } offset->error = (T2 - T1) - (T3 - T4); // Can we use (T4 - OFFSET_1900_1970) instead of time(NULL)? offset->rcvd = time(NULL); offset->good = 1; offset->status.leap = (msg.status & LI_MASK); offset->status.precision = msg.precision; offset->status.rootdelay = sfp_to_d(msg.rootdelay); offset->status.rootdispersion = sfp_to_d(msg.dispersion); offset->status.refid = ntohl(msg.refid); offset->status.refid4 = msg.xmttime.fractionl; offset->status.reftime = lfp_to_d(msg.reftime); offset->status.poll = msg.ppoll; offset->status.stratum = msg.stratum; if (p->trustlevel < TRUSTLEVEL_PATHETIC) interval = scale_interval(INTERVAL_QUERY_PATHETIC); else if (p->trustlevel < TRUSTLEVEL_AGRESSIVE) interval = scale_interval(INTERVAL_QUERY_AGRESSIVE); else interval = scale_interval(INTERVAL_QUERY_NORMAL); set_next(p, interval); p->state = STATE_REPLY_RECEIVED; /* every received reply which we do not discard increases trust */ if (p->trustlevel < TRUSTLEVEL_MAX) { p->trustlevel++; if (p->trustlevel == TRUSTLEVEL_BADPEER) bb_info_msg("peer %s now valid", addr); } bb_info_msg("reply from %s: offset %f delay %f, next query %ds", addr, offset->offset, offset->delay, (int) interval); update_peer_data(p); settime(offset->offset); p->shift++; if (p->shift >= OFFSET_ARRAY_SIZE) p->shift = 0; bail: free(addr); } #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; ntp_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_from_to"); } addr = xmalloc_sockaddr2dotted_noport(from); bb_error_msg("malformed packet received from %s", addr); free(addr); goto bail; } query_status = msg.status; query_ppoll = msg.ppoll; query_xmttime = msg.xmttime; /* Build a reply packet */ memset(&msg, 0, sizeof(msg)); msg.status = G.status.synced ? G.status.leap : LI_ALARM; msg.status |= (query_status & VERSION_MASK); msg.status |= ((query_status & MODE_MASK) == MODE_CLIENT) ? MODE_SERVER : MODE_SYM_PAS; msg.stratum = G.status.stratum; msg.ppoll = query_ppoll; msg.precision = G.status.precision; rectime = gettime1900fp(); msg.xmttime = msg.rectime = d_to_lfp(rectime); msg.reftime = d_to_lfp(G.status.reftime); //msg.xmttime = d_to_lfp(gettime1900fp()); // = msg.rectime msg.orgtime = query_xmttime; msg.rootdelay = d_to_sfp(G.status.rootdelay); version = (query_status & VERSION_MASK); /* ... >> VERSION_SHIFT - done below instead */ msg.refid = (version > (3 << VERSION_SHIFT)) ? G.status.refid4 : G.status.refid; /* We reply from the local address packet was sent to, * this makes to/from look swapped here: */ sendmsg_wrap(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()); /* tzset(); - why? it's called automatically when needed, no? */ 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, "ngqN" /* compat */ "p:"IF_FEATURE_NTPD_SERVER("l") /* NOT compat */ "d" /* compat */ "46aAbLx", /* compat, ignored */ &peers, &G.verbose); if (!(opts & (OPT_p|OPT_l))) bb_show_usage(); #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 if (opts & OPT_g) G.settime = 1; while (peers) add_peers(llist_pop(&peers)); if (!(opts & OPT_n)) { logmode = LOGMODE_NONE; bb_daemonize(DAEMON_DEVNULL_STDIO); } /* 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 */ { 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.status.precision = prec; } G.scale = 1; G.firstadj = 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; ntp_peer_t **idx2peer; memset(&g, 0, sizeof(g)); SET_PTR_TO_GLOBALS(&g); ntp_init(argv); { unsigned cnt = g.peer_cnt; /* if ENABLE_FEATURE_NTPD_SERVER, + 1 for listen_fd: */ idx2peer = xzalloc(sizeof(void *) * (cnt + ENABLE_FEATURE_NTPD_SERVER)); pfd = xzalloc(sizeof(pfd[0]) * (cnt + ENABLE_FEATURE_NTPD_SERVER)); } 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) { ntp_peer_t *p = (ntp_peer_t *) item->data; if (p->next != 0 && p->next <= cur_time) { /* Time to send new req */ trial_cnt++; if (send_query_to_peer(p) == 0) sent_cnt++; } if (p->deadline != 0 && p->deadline <= cur_time) { /* Timed out waiting for reply */ char *addr = xmalloc_sockaddr2dotted_noport(&p->lsa->u.sa); timeout = error_interval(); bb_info_msg("no reply from %s received in time, " "next query %ds", addr, timeout); if (p->trustlevel >= TRUSTLEVEL_BADPEER) { p->trustlevel /= 2; if (p->trustlevel < TRUSTLEVEL_BADPEER) bb_info_msg("peer %s now invalid", addr); } free(addr); set_next(p, timeout); } if (p->next != 0 && p->next < nextaction) nextaction = p->next; if (p->deadline != 0 && p->deadline < nextaction) nextaction = p->deadline; if (p->state == STATE_QUERY_SENT) { /* Wait for reply from this peer */ pfd[i].fd = p->query.fd; pfd[i].events = POLLIN; idx2peer[i] = p; i++; } } if ((trial_cnt > 0 && sent_cnt == 0) || g.peer_cnt == 0) settime(0); /* no good peers, don't wait */ timeout = nextaction - cur_time; if (timeout < 0) timeout = 0; /* Here we may block */ if (g.verbose) bb_error_msg("entering poll %u secs", timeout); 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); }