/* * ntp_proto.c - NTP version 4 protocol machinery * * ATTENTION: Get approval from Dave Mills on all changes to this file! * */ #ifdef HAVE_CONFIG_H #include #endif #include "ntpd.h" #include "ntp_stdlib.h" #include "ntp_unixtime.h" #include "ntp_control.h" #include "ntp_string.h" #include #if defined(VMS) && defined(VMS_LOCALUNIT) /*wjm*/ #include "ntp_refclock.h" #endif #if defined(__FreeBSD__) && __FreeBSD__ >= 3 #include #endif /* * System variables are declared here. See Section 3.2 of the * specification. */ u_char sys_leap; /* system leap indicator */ u_char sys_stratum; /* stratum of system */ s_char sys_precision; /* local clock precision */ double sys_rootdelay; /* roundtrip delay to primary source */ double sys_rootdispersion; /* dispersion to primary source */ u_int32 sys_refid; /* reference source for local clock */ u_int32 sys_peer_refid; /* hashed refid of our current peer */ static double sys_offset; /* current local clock offset */ l_fp sys_reftime; /* time we were last updated */ struct peer *sys_peer; /* our current peer */ struct peer *sys_prefer; /* our cherished peer */ int sys_kod; /* kod credit */ int sys_kod_rate = 2; /* max kod packets per second */ #ifdef OPENSSL u_long sys_automax; /* maximum session key lifetime */ #endif /* OPENSSL */ /* * Nonspecified system state variables. */ int sys_bclient; /* broadcast client enable */ double sys_bdelay; /* broadcast client default delay */ int sys_calldelay; /* modem callup delay (s) */ int sys_authenticate; /* requre authentication for config */ l_fp sys_authdelay; /* authentication delay */ static u_long sys_authdly[2]; /* authentication delay shift reg */ static u_char leap_consensus; /* consensus of survivor leap bits */ static double sys_selerr; /* select error (squares) */ static double sys_syserr; /* system error (squares) */ keyid_t sys_private; /* private value for session seed */ int sys_manycastserver; /* respond to manycast client pkts */ int peer_ntpdate; /* active peers in ntpdate mode */ int sys_survivors; /* truest of the truechimers */ #ifdef OPENSSL char *sys_hostname; /* gethostname() name */ #endif /* OPENSSL */ /* * TOS and multicast mapping stuff */ int sys_floor = 1; /* cluster stratum floor */ int sys_ceiling = STRATUM_UNSPEC; /* cluster stratum ceiling*/ int sys_minsane = 1; /* minimum candidates */ int sys_minclock = NTP_MINCLOCK; /* minimum survivors */ int sys_cohort = 0; /* cohort switch */ int sys_ttlmax; /* max ttl mapping vector index */ u_char sys_ttl[MAX_TTL]; /* ttl mapping vector */ /* * Statistics counters */ u_long sys_stattime; /* time since reset */ u_long sys_received; /* packets received */ u_long sys_processed; /* packets processed */ u_long sys_newversionpkt; /* current version */ u_long sys_oldversionpkt; /* recent version */ u_long sys_unknownversion; /* invalid version */ u_long sys_restricted; /* access denied */ u_long sys_badlength; /* bad length or format */ u_long sys_badauth; /* bad authentication */ u_long sys_limitrejected; /* rate exceeded */ static double root_distance P((struct peer *)); static double clock_combine P((struct peer **, int)); static void peer_xmit P((struct peer *)); static void fast_xmit P((struct recvbuf *, int, keyid_t, int)); static void clock_update P((void)); int default_get_precision P((void)); static int peer_unfit P((struct peer *)); /* * transmit - Transmit Procedure. See Section 3.4.2 of the * specification. */ void transmit( struct peer *peer /* peer structure pointer */ ) { int hpoll; /* * The polling state machine. There are two kinds of machines, * those that never expect a reply (broadcast and manycast * server modes) and those that do (all other modes). The dance * is intricate... */ hpoll = peer->hpoll; if (peer->cast_flags & (MDF_BCAST | MDF_MCAST)) { /* * In broadcast mode the poll interval is fixed * at minpoll. */ hpoll = peer->minpoll; } else if (peer->cast_flags & MDF_ACAST) { /* * In manycast mode we start with the minpoll interval * and ttl. However, the actual poll interval is eight * times the nominal poll interval shown here. If fewer * than sys_minclock servers are found, the ttl is * increased by one and we try again. If this continues * to the max ttl, the poll interval is bumped by one * and we try again. If at least sys_minclock servers * are found, the poll interval increases with the * system poll interval to the max and we continue * indefinately. However, about once per day when the * agreement parameters are refreshed, the manycast * clients are reset and we start from the beginning. * This is to catch and clamp the ttl to the lowest * practical value and avoid knocking on spurious doors. */ if (sys_survivors < sys_minclock && peer->ttl < sys_ttlmax) peer->ttl++; hpoll = sys_poll; } else { /* * For associations expecting a reply, the watchdog * counter is bumped by one if the peer has not been * heard since the previous poll. If the counter reaches * the max, the poll interval is doubled and the peer is * demobilized if not configured. */ peer->unreach++; if (peer->unreach >= NTP_UNREACH) { hpoll++; if (peer->flags & FLAG_CONFIG) { /* * If nothing is likely to change in * future, flash the access denied bit * so we won't bother the dude again. */ if (memcmp((char *)&peer->refid, "DENY", 4) == 0 || memcmp((char *)&peer->refid, "CRYP", 4) == 0) peer->flash |= TEST4; } else { unpeer(peer); return; } } if (peer->burst == 0) { u_char oreach; oreach = peer->reach; peer->reach <<= 1; peer->hyst *= HYST_TC; if (peer->reach == 0) { /* * If this association has become * unreachable, clear it and raise a * trap. */ if (oreach != 0) { report_event(EVNT_UNREACH, peer); peer->timereachable = current_time; if (peer->flags & FLAG_CONFIG) { peer_clear(peer, "INIT"); } else { unpeer(peer); return; } } if (peer->flags & FLAG_IBURST) peer->burst = NTP_BURST; } else { /* * Here the peer is reachable. If it has * not been heard for three consecutive * polls, stuff the clock filter. Next, * determine the poll interval. If the * peer is unfit for synchronization, * increase it by one; otherwise, use * the system poll interval. */ if (!(peer->reach & 0x07)) { clock_filter(peer, 0., 0., MAXDISPERSE); clock_select(); } if (peer_unfit(peer)) hpoll++; else hpoll = sys_poll; if (peer->flags & FLAG_BURST) peer->burst = NTP_BURST; } } else { /* * Source rate control. If we are restrained, * each burst consists of only one packet. */ if (memcmp((char *)&peer->refid, "RSTR", 4) == 0) peer->burst = 0; else peer->burst--; if (peer->burst == 0) { /* * If a broadcast client at this point, * the burst has concluded, so we switch * to client mode and purge the keylist, * since no further transmissions will * be made. */ if (peer->cast_flags & MDF_BCLNT) { peer->hmode = MODE_BCLIENT; #ifdef OPENSSL key_expire(peer); #endif /* OPENSSL */ } poll_update(peer, hpoll); clock_select(); /* * If ntpdate mode and the clock has not * been set and all peers have completed * the burst, we declare a successful * failure. */ if (mode_ntpdate) { peer_ntpdate--; if (peer_ntpdate > 0) { poll_update( peer, hpoll); return; } msyslog(LOG_NOTICE, "no reply; clock not set"); exit (0); } poll_update(peer, hpoll); return; } } } peer->outdate = current_time; /* * Do not transmit if in broadcast cclient mode or access has * been denied. */ if (peer->hmode == MODE_BCLIENT || peer->flash & TEST4) { poll_update(peer, hpoll); return; /* * Do not transmit in broadcast mode unless we are synchronized. */ } else if (peer->hmode == MODE_BROADCAST && sys_peer == NULL) { poll_update(peer, hpoll); return; } peer_xmit(peer); poll_update(peer, hpoll); } /* * receive - Receive Procedure. See section 3.4.3 in the specification. */ void receive( struct recvbuf *rbufp ) { register struct peer *peer; /* peer structure pointer */ register struct pkt *pkt; /* receive packet pointer */ int hismode; /* packet mode */ int restrict_mask; /* restrict bits */ int has_mac; /* length of MAC field */ int authlen; /* offset of MAC field */ int is_authentic; /* cryptosum ok */ keyid_t skeyid = 0; /* key ID */ struct sockaddr_storage *dstadr_sin; /* active runway */ struct peer *peer2; /* aux peer structure pointer */ l_fp p_org; /* originate timestamp */ l_fp p_xmt; /* transmit timestamp */ #ifdef OPENSSL keyid_t tkeyid = 0; /* temporary key ID */ keyid_t pkeyid = 0; /* previous key ID */ struct autokey *ap; /* autokey structure pointer */ int rval; /* cookie snatcher */ #endif /* OPENSSL */ int retcode = AM_NOMATCH; /* * Monitor the packet and get restrictions. Note that the packet * length for control and private mode packets must be checked * by the service routines. Note that no statistics counters are * recorded for restrict violations, since these counters are in * the restriction routine. Note the careful distinctions here * between a packet with a format error and a packet that is * simply discarded without prejudice. Some restrictions have to * be handled later in order to generate a kiss-of-death packet. */ /* * Bogus port check is before anything, since it probably * reveals a clogging attack. */ sys_received++; if (SRCPORT(&rbufp->recv_srcadr) == 0) { sys_badlength++; return; /* bogus port */ } ntp_monitor(rbufp); restrict_mask = restrictions(&rbufp->recv_srcadr); #ifdef DEBUG if (debug > 1) printf("receive: at %ld %s<-%s restrict %03x\n", current_time, stoa(&rbufp->dstadr->sin), stoa(&rbufp->recv_srcadr), restrict_mask); #endif if (restrict_mask & RES_IGNORE) { sys_restricted++; return; /* no anything */ } pkt = &rbufp->recv_pkt; hismode = (int)PKT_MODE(pkt->li_vn_mode); if (hismode == MODE_PRIVATE) { if (restrict_mask & RES_NOQUERY) { sys_restricted++; return; /* no query private */ } process_private(rbufp, ((restrict_mask & RES_NOMODIFY) == 0)); return; } if (hismode == MODE_CONTROL) { if (restrict_mask & RES_NOQUERY) { sys_restricted++; return; /* no query control */ } process_control(rbufp, restrict_mask); return; } if (restrict_mask & RES_DONTSERVE) { sys_restricted++; return; /* no time */ } if (rbufp->recv_length < LEN_PKT_NOMAC) { sys_badlength++; return; /* runt packet */ } /* * Version check must be after the query packets, since they * intentionally use early version. */ if (PKT_VERSION(pkt->li_vn_mode) == NTP_VERSION) { sys_newversionpkt++; /* new version */ } else if (!(restrict_mask & RES_VERSION) && PKT_VERSION(pkt->li_vn_mode) >= NTP_OLDVERSION) { sys_oldversionpkt++; /* previous version */ } else { sys_unknownversion++; return; /* old version */ } /* * Figure out his mode and validate the packet. This has some * legacy raunch that probably should be removed. In very early * NTP versions mode 0 was equivalent to what later versions * would interpret as client mode. */ if (hismode == MODE_UNSPEC) { if (PKT_VERSION(pkt->li_vn_mode) == NTP_OLDVERSION) { hismode = MODE_CLIENT; } else { sys_badlength++; return; /* invalid mode */ } } /* * Discard broadcast if not enabled as broadcast client. If * Autokey, the wildcard interface cannot be used, so dump * packets gettiing off the bus at that stop as well. This means * that some systems with broken interface code, specifically * Linux, will not work with Autokey. */ if (hismode == MODE_BROADCAST) { if (!sys_bclient || restrict_mask & RES_NOPEER) { sys_restricted++; return; /* no client */ } #ifdef OPENSSL if (crypto_flags && rbufp->dstadr == any_interface) { sys_restricted++; return; /* no client */ } #endif /* OPENSSL */ } /* * Parse the extension field if present. We figure out whether * an extension field is present by measuring the MAC size. If * the number of words following the packet header is 0 or 1, no * MAC is present and the packet is not authenticated. If 1, the * packet is a reply to a previous request that failed to * authenticate. If 3, the packet is authenticated with DES; if * 5, the packet is authenticated with MD5. If greater than 5, * an extension field is present. If 2 or 4, the packet is a * runt and goes poof! with a brilliant flash. */ authlen = LEN_PKT_NOMAC; has_mac = rbufp->recv_length - authlen; while (has_mac > 0) { int temp; if (has_mac % 4 != 0 || has_mac < 0) { sys_badlength++; return; /* bad MAC length */ } if (has_mac == 1 * 4 || has_mac == 3 * 4 || has_mac == MAX_MAC_LEN) { skeyid = ntohl(((u_int32 *)pkt)[authlen / 4]); break; } else if (has_mac > MAX_MAC_LEN) { temp = ntohl(((u_int32 *)pkt)[authlen / 4]) & 0xffff; if (temp < 4 || temp > NTP_MAXEXTEN || temp % 4 != 0) { sys_badlength++; return; /* bad MAC length */ } authlen += temp; has_mac -= temp; } else { sys_badlength++; return; /* bad MAC length */ } } #ifdef OPENSSL pkeyid = tkeyid = 0; #endif /* OPENSSL */ /* * We have tossed out as many buggy packets as possible early in * the game to reduce the exposure to a clogging attack. Now we * have to burn some cycles to find the association and * authenticate the packet if required. Note that we burn only * MD5 cycles, again to reduce exposure. There may be no * matching association and that's okay. * * More on the autokey mambo. Normally the local interface is * found when the association was mobilized with respect to a * designated remote address. We assume packets arriving from * the remote address arrive via this interface and the local * address used to construct the autokey is the unicast address * of the interface. However, if the sender is a broadcaster, * the interface broadcast address is used instead. * Notwithstanding this technobabble, if the sender is a * multicaster, the broadcast address is null, so we use the * unicast address anyway. Don't ask. */ peer = findpeer(&rbufp->recv_srcadr, rbufp->dstadr, rbufp->fd, hismode, &retcode); is_authentic = 0; dstadr_sin = &rbufp->dstadr->sin; if (has_mac == 0) { #ifdef DEBUG if (debug) printf("receive: at %ld %s<-%s mode %d code %d\n", current_time, stoa(&rbufp->dstadr->sin), stoa(&rbufp->recv_srcadr), hismode, retcode); #endif } else { #ifdef OPENSSL /* * For autokey modes, generate the session key * and install in the key cache. Use the socket * broadcast or unicast address as appropriate. */ if (skeyid > NTP_MAXKEY) { /* * More on the autokey dance (AKD). A cookie is * constructed from public and private values. * For broadcast packets, the cookie is public * (zero). For packets that match no * association, the cookie is hashed from the * addresses and private value. For server * packets, the cookie was previously obtained * from the server. For symmetric modes, the * cookie was previously constructed using an * agreement protocol; however, should PKI be * unavailable, we construct a fake agreement as * the EXOR of the peer and host cookies. * * hismode ephemeral persistent * ======================================= * active 0 cookie# * passive 0% cookie# * client sys cookie 0% * server 0% sys cookie * broadcast 0 0 * * # if unsync, 0 * % can't happen */ if (hismode == MODE_BROADCAST) { /* * For broadcaster, use the interface * broadcast address when available; * otherwise, use the unicast address * found when the association was * mobilized. */ pkeyid = 0; if (!SOCKNUL(&rbufp->dstadr->bcast)) dstadr_sin = &rbufp->dstadr->bcast; } else if (peer == NULL) { pkeyid = session_key( &rbufp->recv_srcadr, dstadr_sin, 0, sys_private, 0); } else { pkeyid = peer->pcookie; } /* * The session key includes both the public * values and cookie. In case of an extension * field, the cookie used for authentication * purposes is zero. Note the hash is saved for * use later in the autokey mambo. */ if (authlen > LEN_PKT_NOMAC && pkeyid != 0) { session_key(&rbufp->recv_srcadr, dstadr_sin, skeyid, 0, 2); tkeyid = session_key( &rbufp->recv_srcadr, dstadr_sin, skeyid, pkeyid, 0); } else { tkeyid = session_key( &rbufp->recv_srcadr, dstadr_sin, skeyid, pkeyid, 2); } } #endif /* OPENSSL */ /* * Compute the cryptosum. Note a clogging attack may * succeed in bloating the key cache. If an autokey, * purge it immediately, since we won't be needing it * again. If the packet is authentic, it may mobilize an * association. */ if (authdecrypt(skeyid, (u_int32 *)pkt, authlen, has_mac)) { is_authentic = 1; restrict_mask &= ~RES_DONTTRUST; } else { sys_badauth++; } #ifdef OPENSSL if (skeyid > NTP_MAXKEY) authtrust(skeyid, 0); #endif /* OPENSSL */ #ifdef DEBUG if (debug) printf( "receive: at %ld %s<-%s mode %d code %d keyid %08x len %d mac %d auth %d\n", current_time, stoa(dstadr_sin), stoa(&rbufp->recv_srcadr), hismode, retcode, skeyid, authlen, has_mac, is_authentic); #endif } /* * The association matching rules are implemented by a set of * routines and a table in ntp_peer.c. A packet matching an * association is processed by that association. If not and * certain conditions prevail, then an ephemeral association is * mobilized: a broadcast packet mobilizes a broadcast client * aassociation; a manycast server packet mobilizes a manycast * client association; a symmetric active packet mobilizes a * symmetric passive association. And, the adventure * continues... */ switch (retcode) { case AM_FXMIT: /* * This is a client mode packet not matching a known * association. If from a manycast client we run a few * sanity checks before deciding to send a unicast * server response. Otherwise, it must be a client * request, so send a server response and go home. */ if (sys_manycastserver && (rbufp->dstadr->flags & INT_MULTICAST)) { /* * There is no reason to respond to a request if * our time is worse than the manycaster or it * has already synchronized to us. */ if (sys_peer == NULL || PKT_TO_STRATUM(pkt->stratum) < sys_stratum || (sys_cohort && PKT_TO_STRATUM(pkt->stratum) == sys_stratum) || rbufp->dstadr->addr_refid == pkt->refid) return; /* manycast dropped */ } /* * Note that we don't require an authentication check * here, since we can't set the system clock; but, we do * send a crypto-NAK to tell the caller about this. */ if (has_mac && !is_authentic) fast_xmit(rbufp, MODE_SERVER, 0, restrict_mask); else fast_xmit(rbufp, MODE_SERVER, skeyid, restrict_mask); return; case AM_MANYCAST: /* * This is a server mode packet returned in response to * a client mode packet sent to a multicast group * address. The originate timestamp is a good nonce to * reliably associate the reply with what was sent. If * there is no match, that's curious and could be an * intruder attempting to clog, so we just ignore it. * * First, make sure the packet is authentic and not * restricted. If so and the manycast association is * found, we mobilize a client association and copy * pertinent variables from the manycast association to * the new client association. * * There is an implosion hazard at the manycast client, * since the manycast servers send the server packet * immediately. If the guy is already here, don't fire * up a duplicate. */ if (restrict_mask & RES_DONTTRUST) { sys_restricted++; return; /* no trust */ } if (sys_authenticate && !is_authentic) return; /* bad auth */ if ((peer2 = findmanycastpeer(rbufp)) == NULL) return; /* no assoc match */ if ((peer = newpeer(&rbufp->recv_srcadr, rbufp->dstadr, MODE_CLIENT, PKT_VERSION(pkt->li_vn_mode), NTP_MINDPOLL, NTP_MAXDPOLL, FLAG_IBURST, MDF_UCAST | MDF_ACLNT, 0, skeyid)) == NULL) return; /* system error */ /* * We don't need these, but it warms the billboards. */ peer->ttl = peer2->ttl; break; case AM_NEWPASS: /* * This is the first packet received from a symmetric * active peer. First, make sure it is authentic and not * restricted. If so, mobilize a passive association. * If authentication fails send a crypto-NAK; otherwise, * kiss the frog. */ if (restrict_mask & RES_DONTTRUST) { sys_restricted++; return; /* no trust */ } if (sys_authenticate && !is_authentic) { fast_xmit(rbufp, MODE_PASSIVE, 0, restrict_mask); return; /* bad auth */ } if ((peer = newpeer(&rbufp->recv_srcadr, rbufp->dstadr, MODE_PASSIVE, PKT_VERSION(pkt->li_vn_mode), NTP_MINDPOLL, NTP_MAXDPOLL, 0, MDF_UCAST, 0, skeyid)) == NULL) return; /* system error */ break; case AM_NEWBCL: /* * This is the first packet received from a broadcast * server. First, make sure it is authentic and not * restricted and that we are a broadcast client. If so, * mobilize a broadcast client association. We don't * kiss any frogs here. */ if (restrict_mask & RES_DONTTRUST) { sys_restricted++; return; /* no trust */ } if (sys_authenticate && !is_authentic) return; /* bad auth */ if (!sys_bclient) return; /* not a client */ if ((peer = newpeer(&rbufp->recv_srcadr, rbufp->dstadr, MODE_CLIENT, PKT_VERSION(pkt->li_vn_mode), NTP_MINDPOLL, NTP_MAXDPOLL, FLAG_MCAST | FLAG_IBURST, MDF_BCLNT, 0, skeyid)) == NULL) return; /* system error */ #ifdef OPENSSL /* * Danger looms. If this is autokey, go process the * extension fields. If something goes wrong, abandon * ship and don't trust subsequent packets. */ if (crypto_flags) { if ((rval = crypto_recv(peer, rbufp)) != XEVNT_OK) { struct sockaddr_storage mskadr_sin; unpeer(peer); sys_restricted++; SET_HOSTMASK(&mskadr_sin, rbufp->recv_srcadr.ss_family); hack_restrict(RESTRICT_FLAGS, &rbufp->recv_srcadr, &mskadr_sin, 0, RES_DONTTRUST | RES_TIMEOUT); #ifdef DEBUG if (debug) printf( "packet: bad exten %x\n", rval); #endif } } #endif /* OPENSSL */ return; case AM_POSSBCL: /* * This is a broadcast packet received in client mode. * It could happen if the initial client/server volley * is not complete before the next broadcast packet is * received. Be liberal in what we accept. */ case AM_PROCPKT: /* * This is a symmetric mode packet received in symmetric * mode, a server packet received in client mode or a * broadcast packet received in broadcast client mode. * If it is restricted, this is very strange because it * is rude to send a packet to a restricted address. If * anyway, flash a restrain kiss and skedaddle to * Seattle. If not authentic, leave a light on and * continue. */ peer->flash = 0; if (restrict_mask & RES_DONTTRUST) { sys_restricted++; if (peer->flags & FLAG_CONFIG) peer_clear(peer, "RSTR"); else unpeer(peer); return; /* no trust */ } if (has_mac && !is_authentic) peer->flash |= TEST5; /* bad auth */ break; default: /* * Invalid mode combination. This happens when a passive * mode packet arrives and matches another passive * association or no association at all, or when a * server mode packet arrives and matches a broadcast * client association. This is usually the result of * reconfiguring a client on-fly. If authenticated * passive mode packet, send a crypto-NAK; otherwise, * ignore it. */ if (has_mac && hismode == MODE_PASSIVE) fast_xmit(rbufp, MODE_ACTIVE, 0, restrict_mask); #ifdef DEBUG if (debug) printf("receive: bad protocol %d\n", retcode); #endif return; } /* * We do a little homework. Note we can get here with an * authentication error. We Need to do this in order to validate * a crypto-NAK later. Note the order of processing; it is very * important to avoid livelocks, deadlocks and lockpicks. */ peer->timereceived = current_time; peer->received++; if (peer->flash & TEST5) peer->flags &= ~FLAG_AUTHENTIC; else peer->flags |= FLAG_AUTHENTIC; NTOHL_FP(&pkt->org, &p_org); NTOHL_FP(&pkt->xmt, &p_xmt); /* * If the packet is an old duplicate, we let it through so the * extension fields will be processed. */ if (L_ISEQU(&peer->org, &p_xmt)) { /* test 1 */ peer->flash |= TEST1; /* dupe */ /* fall through */ /* * For broadcast server mode, loopback checking is disabled. An * authentication error probably means the server restarted or * rolled a new private value. If so, dump the association * and wait for the next message. */ } else if (hismode == MODE_BROADCAST) { if (peer->flash & TEST5) { unpeer(peer); return; } /* fall through */ /* * For server and symmetric modes, if the association transmit * timestamp matches the packet originate timestamp, loopback is * confirmed. Note in symmetric modes this also happens when the * first packet from the active peer arrives at the newly * mobilized passive peer. An authentication error probably * means the server or peer restarted or rolled a new private * value, but could be an intruder trying to stir up trouble. * However, if this is a crypto-NAK, we know it is authentic, so * dump the association and wait for the next message. */ } else if (L_ISEQU(&peer->xmt, &p_org)) { if (peer->flash & TEST5) { if (has_mac == 4 && pkt->exten[0] == 0) { if (peer->flags & FLAG_CONFIG) peer_clear(peer, "AUTH"); else unpeer(peer); } return; } /* fall through */ /* * If the client or passive peer has never transmitted anything, * this is either the first message from a symmetric peer or * possibly a duplicate received before the transmit timeout. * Pass it on. */ } else if (L_ISZERO(&peer->xmt)) { /* fall through */ /* * Now it gets interesting. We have transmitted at least one * packet. If the packet originate timestamp is nonzero, it * does not match the association transmit timestamp, which is a * loopback error. This error might mean a manycast server has * answered a manycast honk from us and we already have an * association for him, in which case quietly drop the packet * here. It might mean an old duplicate, dropped packet or * intruder replay, in which case we drop it later after * extension field processing, but never let it touch the time * values. */ } else if (!L_ISZERO(&p_org)) { if (peer->cast_flags & MDF_ACLNT) return; /* not a client */ peer->flash |= TEST2; /* fall through */ /* * The packet originate timestamp is zero, meaning the other guy * either didn't receive the first packet or died and restarted. * If the association originate timestamp is zero, this is the * first packet received, so we pass it on. */ } else if (L_ISZERO(&peer->org)) { /* fall through */ /* * The other guy has restarted and we are still on the wire. We * should demobilize/clear and get out of Dodge. If this is * symmetric mode, we should also send a crypto-NAK. */ } else { if (hismode == MODE_ACTIVE) fast_xmit(rbufp, MODE_PASSIVE, 0, restrict_mask); else if (hismode == MODE_PASSIVE) fast_xmit(rbufp, MODE_ACTIVE, 0, restrict_mask); #if DEBUG if (debug) printf("receive: dropped %03x\n", peer->flash); #endif if (peer->flags & FLAG_CONFIG) peer_clear(peer, "DROP"); else unpeer(peer); return; } if (peer->flash & ~TEST2) { return; } #ifdef OPENSSL /* * More autokey dance. The rules of the cha-cha are as follows: * * 1. If there is no key or the key is not auto, do nothing. * * 2. If this packet is in response to the one just previously * sent or from a broadcast server, do the extension fields. * Otherwise, assume bogosity and bail out. * * 3. If an extension field contains a verified signature, it is * self-authenticated and we sit the dance. * * 4. If this is a server reply, check only to see that the * transmitted key ID matches the received key ID. * * 5. Check to see that one or more hashes of the current key ID * matches the previous key ID or ultimate original key ID * obtained from the broadcaster or symmetric peer. If no * match, sit the dance and wait for timeout. */ if (crypto_flags && (peer->flags & FLAG_SKEY)) { peer->flash |= TEST10; rval = crypto_recv(peer, rbufp); if (rval != XEVNT_OK) { /* fall through */ } else if (hismode == MODE_SERVER) { if (skeyid == peer->keyid) peer->flash &= ~TEST10; } else if (!peer->flash & TEST10) { peer->pkeyid = skeyid; } else if ((ap = (struct autokey *)peer->recval.ptr) != NULL) { int i; for (i = 0; ; i++) { if (tkeyid == peer->pkeyid || tkeyid == ap->key) { peer->flash &= ~TEST10; peer->pkeyid = skeyid; break; } if (i > ap->seq) break; tkeyid = session_key( &rbufp->recv_srcadr, dstadr_sin, tkeyid, pkeyid, 0); } } if (!(peer->crypto & CRYPTO_FLAG_PROV)) /* test 11 */ peer->flash |= TEST11; /* not proventic */ /* * If the transmit queue is nonempty, clamp the host * poll interval to the packet poll interval. */ if (peer->cmmd != 0) { peer->ppoll = pkt->ppoll; poll_update(peer, 0); } /* * If the return code from extension field processing is * not okay, we scrub the association and start over. */ if (rval != XEVNT_OK) { /* * If the return code is bad, the crypto machine * may be jammed or an intruder may lurk. First, * we demobilize the association, then see if * the error is recoverable. */ if (peer->flags & FLAG_CONFIG) peer_clear(peer, "CRYP"); else unpeer(peer); #ifdef DEBUG if (debug) printf("packet: bad exten %x\n", rval); #endif return; } /* * If TEST10 is lit, the autokey sequence has broken, * which probably means the server has refreshed its * private value. We reset the poll interval to the & minimum and scrub the association clean. */ if (peer->flash & TEST10 && peer->crypto & CRYPTO_FLAG_AUTO) { poll_update(peer, peer->minpoll); #ifdef DEBUG if (debug) printf( "packet: bad auto %03x\n", peer->flash); #endif if (peer->flags & FLAG_CONFIG) peer_clear(peer, "AUTO"); else unpeer(peer); return; } } #endif /* OPENSSL */ /* * We have survived the gaunt. Forward to the packet routine. If * a symmetric passive association has been mobilized and the * association doesn't deserve to live, it will die in the * transmit routine if not reachable after timeout. However, if * either symmetric mode and the crypto code has something * urgent to say, we expedite the response. */ process_packet(peer, pkt, &rbufp->recv_time); } /* * process_packet - Packet Procedure, a la Section 3.4.4 of the * specification. Or almost, at least. If we're in here we have a * reasonable expectation that we will be having a long term * relationship with this host. */ void process_packet( register struct peer *peer, register struct pkt *pkt, l_fp *recv_ts ) { l_fp t34, t21; double p_offset, p_del, p_disp; double dtemp; l_fp p_rec, p_xmt, p_org, p_reftime; l_fp ci; u_char pmode, pleap, pstratum; /* * Swap header fields and keep the books. The books amount to * the receive timestamp and poll interval in the header. We * need these even if there are other problems in order to crank * up the state machine. */ sys_processed++; peer->processed++; p_del = FPTOD(NTOHS_FP(pkt->rootdelay)); p_disp = FPTOD(NTOHS_FP(pkt->rootdispersion)); NTOHL_FP(&pkt->reftime, &p_reftime); NTOHL_FP(&pkt->rec, &p_rec); NTOHL_FP(&pkt->xmt, &p_xmt); pmode = PKT_MODE(pkt->li_vn_mode); pleap = PKT_LEAP(pkt->li_vn_mode); if (pmode != MODE_BROADCAST) NTOHL_FP(&pkt->org, &p_org); else p_org = peer->rec; pstratum = PKT_TO_STRATUM(pkt->stratum); /* * Test for unsynchronized server. */ if (L_ISHIS(&peer->org, &p_xmt)) /* count old packets */ peer->oldpkt++; if (pmode != MODE_BROADCAST && (L_ISZERO(&p_rec) || L_ISZERO(&p_org))) /* test 3 */ peer->flash |= TEST3; /* unsynch */ if (L_ISZERO(&p_xmt)) /* test 3 */ peer->flash |= TEST3; /* unsynch */ /* * If any tests fail, the packet is discarded leaving only the * timestamps, which are enough to get the protocol started. The * originate timestamp is copied from the packet transmit * timestamp and the receive timestamp is copied from the * packet receive timestamp. If okay so far, we save the leap, * stratum and refid for billboards. */ peer->org = p_xmt; peer->rec = *recv_ts; if (peer->flash) { #ifdef DEBUG if (debug) printf("packet: bad data %03x from address: %s\n", peer->flash, stoa(&peer->srcadr)); #endif return; } peer->leap = pleap; peer->stratum = pstratum; peer->refid = pkt->refid; /* * Test for valid peer data (tests 6-8) */ ci = p_xmt; L_SUB(&ci, &p_reftime); LFPTOD(&ci, dtemp); if (pleap == LEAP_NOTINSYNC || /* test 6 */ pstratum >= STRATUM_UNSPEC || dtemp < 0) peer->flash |= TEST6; /* bad synch */ if (!(peer->flags & FLAG_CONFIG) && sys_peer != NULL) { /* test 7 */ if (pstratum > sys_stratum && pmode != MODE_ACTIVE) peer->flash |= TEST7; /* bad stratum */ } if (p_del < 0 || p_disp < 0 || p_del / /* test 8 */ 2 + p_disp >= MAXDISPERSE) peer->flash |= TEST8; /* bad peer values */ /* * If any tests fail at this point, the packet is discarded. */ if (peer->flash) { #ifdef DEBUG if (debug) printf("packet: bad header %03x\n", peer->flash); #endif return; } /* * The header is valid. Capture the remaining header values and * mark as reachable. */ record_raw_stats(&peer->srcadr, &peer->dstadr->sin, &p_org, &p_rec, &p_xmt, &peer->rec); peer->pmode = pmode; peer->ppoll = pkt->ppoll; peer->precision = pkt->precision; peer->rootdelay = p_del; peer->rootdispersion = p_disp; peer->reftime = p_reftime; if (!(peer->reach)) { report_event(EVNT_REACH, peer); peer->timereachable = current_time; } peer->reach |= 1; peer->unreach = 0; poll_update(peer, 0); /* * If running in a client/server association, calculate the * clock offset c, roundtrip delay d and dispersion e. We use * the equations (reordered from those in the spec). Note that, * in a broadcast association, org has been set to the time of * last reception. Note the computation of dispersion includes * the system precision plus that due to the frequency error * since the originate time. * * Let t1 = p_org, t2 = p_rec, t3 = p_xmt, t4 = peer->rec: */ t34 = p_xmt; /* t3 - t4 */ L_SUB(&t34, &peer->rec); t21 = p_rec; /* t2 - t1 */ L_SUB(&t21, &p_org); ci = peer->rec; /* t4 - t1 */ L_SUB(&ci, &p_org); LFPTOD(&ci, p_disp); p_disp = clock_phi * max(p_disp, LOGTOD(sys_precision)); /* * If running in a broadcast association, the clock offset is * (t1 - t0) corrected by the one-way delay, but we can't * measure that directly. Therefore, we start up in MODE_CLIENT * mode, set FLAG_MCAST and exchange eight messages to determine * the clock offset. When the last message is sent, we switch to * MODE_BCLIENT mode. The next broadcast message after that * computes the broadcast offset and clears FLAG_MCAST. */ ci = t34; if (pmode == MODE_BROADCAST) { if (peer->flags & FLAG_MCAST) { LFPTOD(&ci, p_offset); peer->estbdelay = peer->offset - p_offset; if (peer->hmode == MODE_CLIENT) return; peer->flags &= ~FLAG_MCAST; } DTOLFP(peer->estbdelay, &t34); L_ADD(&ci, &t34); p_del = peer->delay; } else { L_ADD(&ci, &t21); /* (t2 - t1) + (t3 - t4) */ L_RSHIFT(&ci); L_SUB(&t21, &t34); /* (t2 - t1) - (t3 - t4) */ LFPTOD(&t21, p_del); } p_del = max(p_del, LOGTOD(sys_precision)); LFPTOD(&ci, p_offset); if ((peer->rootdelay + p_del) / 2. + peer->rootdispersion + p_disp >= MAXDISPERSE) /* test 9 */ peer->flash |= TEST9; /* bad root distance */ /* * If any flasher bits remain set at this point, abandon ship. * Otherwise, forward to the clock filter. */ if (peer->flash) { #ifdef DEBUG if (debug) printf("packet: bad packet data %03x\n", peer->flash); #endif return; } clock_filter(peer, p_offset, p_del, p_disp); clock_select(); record_peer_stats(&peer->srcadr, ctlpeerstatus(peer), peer->offset, peer->delay, peer->disp, SQRT(peer->jitter)); } /* * clock_update - Called at system process update intervals. */ static void clock_update(void) { u_char oleap; u_char ostratum; /* * Reset/adjust the system clock. Do this only if there is a * system peer and the peer epoch is not older than the last * update. */ if (sys_peer == NULL) return; if (sys_peer->epoch <= last_time) return; #ifdef DEBUG if (debug) printf("clock_update: at %ld assoc %d \n", current_time, peer_associations); #endif oleap = sys_leap; ostratum = sys_stratum; switch (local_clock(sys_peer, sys_offset, sys_syserr)) { /* * Clock is too screwed up. Just exit for now. */ case -1: report_event(EVNT_SYSFAULT, NULL); exit (-1); /*NOTREACHED*/ /* * Clock was stepped. Flush all time values of all peers. */ case 1: clear_all(); sys_peer = NULL; sys_stratum = STRATUM_UNSPEC; memcpy(&sys_refid, "STEP", 4); sys_poll = NTP_MINPOLL; report_event(EVNT_CLOCKRESET, NULL); #ifdef OPENSSL if (oleap != LEAP_NOTINSYNC) expire_all(); #endif /* OPENSSL */ break; /* * Update the system stratum, leap bits, root delay, root * dispersion, reference ID and reference time. We also update * select dispersion and max frequency error. If the leap * changes, we gotta reroll the keys. */ default: sys_stratum = (u_char) (sys_peer->stratum + 1); if (sys_stratum == 1 || sys_stratum == STRATUM_UNSPEC) sys_refid = sys_peer->refid; else sys_refid = sys_peer_refid; sys_reftime = sys_peer->rec; sys_rootdelay = sys_peer->rootdelay + sys_peer->delay; sys_leap = leap_consensus; if (oleap == LEAP_NOTINSYNC) { report_event(EVNT_SYNCCHG, NULL); #ifdef OPENSSL expire_all(); #endif /* OPENSSL */ } } if (ostratum != sys_stratum) report_event(EVNT_PEERSTCHG, NULL); } /* * poll_update - update peer poll interval */ void poll_update( struct peer *peer, int hpoll ) { #ifdef OPENSSL int oldpoll; #endif /* OPENSSL */ /* * A little foxtrot to determine what controls the poll * interval. If the peer is reachable, but the last four polls * have not been answered, use the minimum. If declared * truechimer, use the system poll interval. This allows each * association to ramp up the poll interval for useless sources * and to clamp it to the minimum when first starting up. */ #ifdef OPENSSL oldpoll = peer->kpoll; #endif /* OPENSSL */ if (hpoll > 0) { if (hpoll > peer->maxpoll) peer->hpoll = peer->maxpoll; else if (hpoll < peer->minpoll) peer->hpoll = peer->minpoll; else peer->hpoll = (u_char)hpoll; } /* * Bit of adventure here. If during a burst and not a poll, just * slink away. If a poll, figure what the next poll should be. * If a burst is pending and a reference clock or a pending * crypto response, delay for one second. If the first sent in a * burst, delay ten seconds for the modem to come up. For others * in the burst, delay two seconds. * * In case of manycast server, make the poll interval, which is * axtually the manycast beacon interval, eight times the system * poll interval. Normally when the host poll interval settles * up to 1024 s, the beacon interval settles up to 2.3 hours. */ #ifdef OPENSSL if (peer->cmmd != NULL && (sys_leap != LEAP_NOTINSYNC || peer->crypto)) { peer->nextdate = current_time + RESP_DELAY; } else if (peer->burst > 0) { #else /* OPENSSL */ if (peer->burst > 0) { #endif /* OPENSSL */ if (hpoll == 0 && peer->nextdate != current_time) return; #ifdef REFCLOCK else if (peer->flags & FLAG_REFCLOCK) peer->nextdate += RESP_DELAY; #endif else if (peer->flags & (FLAG_IBURST | FLAG_BURST) && peer->burst == NTP_BURST) peer->nextdate += sys_calldelay; else peer->nextdate += BURST_DELAY; } else if (peer->cast_flags & MDF_ACAST) { if (sys_survivors >= sys_minclock || peer->ttl >= sys_ttlmax) peer->kpoll = (u_char) (peer->hpoll + 3); else peer->kpoll = peer->hpoll; peer->nextdate = peer->outdate + RANDPOLL(peer->kpoll); } else { peer->kpoll = (u_char) max(min(peer->ppoll, peer->hpoll), peer->minpoll); peer->nextdate = peer->outdate + RANDPOLL(peer->kpoll); } if (peer->nextdate < current_time) peer->nextdate = current_time; #ifdef OPENSSL /* * Bit of crass arrogance at this point. If the poll interval * has changed and we have a keylist, the lifetimes in the * keylist are probably bogus. In this case purge the keylist * and regenerate it later. */ if (peer->kpoll != oldpoll) key_expire(peer); #endif /* OPENSSL */ #ifdef DEBUG if (debug > 1) printf("poll_update: at %lu %s flags %04x poll %d burst %d last %lu next %lu\n", current_time, ntoa(&peer->srcadr), peer->flags, peer->kpoll, peer->burst, peer->outdate, peer->nextdate); #endif } /* * clear - clear peer filter registers. See Section 3.4.8 of the spec. */ void peer_clear( struct peer *peer, /* peer structure */ char *ident /* tally lights */ ) { u_char oreach, i; /* * If cryptographic credentials have been acquired, toss them to * Valhalla. Note that autokeys are ephemeral, in that they are * tossed immediately upon use. Therefore, the keylist can be * purged anytime without needing to preserve random keys. Note * that, if the peer is purged, the cryptographic variables are * purged, too. This makes it much harder to sneak in some * unauthenticated data in the clock filter. */ oreach = peer->reach; #ifdef OPENSSL key_expire(peer); if (peer->pkey != NULL) EVP_PKEY_free(peer->pkey); if (peer->ident_pkey != NULL) EVP_PKEY_free(peer->ident_pkey); if (peer->subject != NULL) free(peer->subject); if (peer->issuer != NULL) free(peer->issuer); if (peer->iffval != NULL) BN_free(peer->iffval); if (peer->grpkey != NULL) BN_free(peer->grpkey); if (peer->cmmd != NULL) free(peer->cmmd); value_free(&peer->cookval); value_free(&peer->recval); value_free(&peer->tai_leap); value_free(&peer->encrypt); value_free(&peer->sndval); #endif /* OPENSSL */ /* * Wipe the association clean and initialize the nonzero values. */ memset(CLEAR_TO_ZERO(peer), 0, LEN_CLEAR_TO_ZERO); if (peer == sys_peer) sys_peer = NULL; peer->estbdelay = sys_bdelay; peer->hpoll = peer->kpoll = peer->minpoll; peer->ppoll = peer->maxpoll; peer->jitter = MAXDISPERSE; peer->epoch = current_time; #ifdef REFCLOCK if (!(peer->flags & FLAG_REFCLOCK)) { peer->leap = LEAP_NOTINSYNC; peer->stratum = STRATUM_UNSPEC; memcpy(&peer->refid, ident, 4); } #else peer->leap = LEAP_NOTINSYNC; peer->stratum = STRATUM_UNSPEC; memcpy(&peer->refid, ident, 4); #endif for (i = 0; i < NTP_SHIFT; i++) { peer->filter_order[i] = i; peer->filter_disp[i] = MAXDISPERSE; peer->filter_epoch[i] = current_time; } /* * If he dies as a broadcast client, he comes back to life as * a broadcast client in client mode in order to recover the * initial autokey values. */ if (peer->cast_flags & MDF_BCLNT) { peer->flags |= FLAG_MCAST; peer->hmode = MODE_CLIENT; } /* * Randomize the first poll to avoid bunching, but only if the * rascal has never been heard. During initialization use the * association count to spread out the polls at one-second * intervals. */ peer->nextdate = peer->update = peer->outdate = current_time; peer->burst = 0; if (oreach) poll_update(peer, 0); else if (initializing) peer->nextdate = current_time + peer_associations; else peer->nextdate = current_time + (u_int)RANDOM % peer_associations; #ifdef DEBUG if (debug) printf("peer_clear: at %ld assoc ID %d refid %s\n", current_time, peer->associd, ident); #endif } /* * clock_filter - add incoming clock sample to filter register and run * the filter procedure to find the best sample. */ void clock_filter( struct peer *peer, /* peer structure pointer */ double sample_offset, /* clock offset */ double sample_delay, /* roundtrip delay */ double sample_disp /* dispersion */ ) { double dst[NTP_SHIFT]; /* distance vector */ int ord[NTP_SHIFT]; /* index vector */ int i, j, k, m; double dsp, jit, dtemp, etemp; /* * Shift the new sample into the register and discard the oldest * one. The new offset and delay come directly from the * timestamp calculations. The dispersion grows from the last * outbound packet or reference clock update to the present time * and increased by the sum of the peer precision and the system * precision. The delay can sometimes swing negative due to * frequency skew, so it is clamped non-negative. */ dsp = min(LOGTOD(peer->precision) + LOGTOD(sys_precision) + sample_disp, MAXDISPERSE); j = peer->filter_nextpt; peer->filter_offset[j] = sample_offset; peer->filter_delay[j] = max(0, sample_delay); peer->filter_disp[j] = dsp; j++; j %= NTP_SHIFT; peer->filter_nextpt = (u_short) j; /* * Update dispersions since the last update and at the same * time initialize the distance and index lists. The distance * list uses a compound metric. If the sample is valid and * younger than the minimum Allan intercept, use delay; * otherwise, use biased dispersion. */ dtemp = clock_phi * (current_time - peer->update); peer->update = current_time; for (i = NTP_SHIFT - 1; i >= 0; i--) { if (i != 0) peer->filter_disp[j] += dtemp; if (peer->filter_disp[j] >= MAXDISPERSE) peer->filter_disp[j] = MAXDISPERSE; if (peer->filter_disp[j] >= MAXDISPERSE) dst[i] = MAXDISPERSE; else if (peer->update - peer->filter_epoch[j] > allan_xpt) dst[i] = MAXDISTANCE + peer->filter_disp[j]; else dst[i] = peer->filter_delay[j]; ord[i] = j; j++; j %= NTP_SHIFT; } peer->filter_epoch[j] = current_time; /* * Sort the samples in both lists by distance. */ for (i = 1; i < NTP_SHIFT; i++) { for (j = 0; j < i; j++) { if (dst[j] > dst[i]) { k = ord[j]; ord[j] = ord[i]; ord[i] = k; etemp = dst[j]; dst[j] = dst[i]; dst[i] = etemp; } } } /* * Copy the index list to the association structure so ntpq * can see it later. Prune the distance list to samples less * than MAXDISTANCE, but keep at least two valid samples for * jitter calculation. */ m = 0; for (i = 0; i < NTP_SHIFT; i++) { peer->filter_order[i] = (u_char) ord[i]; if (dst[i] >= MAXDISPERSE || (m >= 2 && dst[i] >= MAXDISTANCE)) continue; m++; } /* * Compute the dispersion and jitter squares. The dispersion * is weighted exponentially by NTP_FWEIGHT (0.5) so it is * normalized close to 1.0. The jitter is the mean of the square * differences relative to the lowest delay sample. If no * acceptable samples remain in the shift register, quietly * tiptoe home leaving only the dispersion. */ jit = 0; peer->disp = 0; k = ord[0]; for (i = NTP_SHIFT - 1; i >= 0; i--) { j = ord[i]; peer->disp = NTP_FWEIGHT * (peer->disp + peer->filter_disp[j]); if (i < m) jit += DIFF(peer->filter_offset[j], peer->filter_offset[k]); } /* * If no acceptable samples remain in the shift register, * quietly tiptoe home leaving only the dispersion. Otherwise, * save the offset, delay and jitter average. Note the jitter * must not be less than the system precision. */ if (m == 0) return; etemp = fabs(peer->offset - peer->filter_offset[k]); dtemp = sqrt(peer->jitter); peer->offset = peer->filter_offset[k]; peer->delay = peer->filter_delay[k]; if (m > 1) jit /= m - 1; peer->jitter = max(jit, SQUARE(LOGTOD(sys_precision))); /* * A new sample is useful only if it is younger than the last * one used, but only if the sucker has been synchronized. */ if (peer->filter_epoch[k] <= peer->epoch && sys_leap != LEAP_NOTINSYNC) { #ifdef DEBUG if (debug) printf("clock_filter: discard %lu\n", peer->epoch - peer->filter_epoch[k]); #endif return; } /* * If the difference between the last offset and the current one * exceeds the jitter by CLOCK_SGATE and the interval since the * last update is less than twice the system poll interval, * consider the update a popcorn spike and ignore it. */ if (m > 1 && etemp > CLOCK_SGATE * dtemp && (long)(peer->filter_epoch[k] - peer->epoch) < (1 << (sys_poll + 1))) { #ifdef DEBUG if (debug) printf("clock_filter: popcorn %.6f %.6f\n", etemp, dtemp); #endif return; } /* * The mitigated sample statistics are saved for later * processing. */ peer->epoch = peer->filter_epoch[k]; #ifdef DEBUG if (debug) printf( "clock_filter: n %d off %.6f del %.6f dsp %.6f jit %.6f, age %lu\n", m, peer->offset, peer->delay, peer->disp, SQRT(peer->jitter), peer->update - peer->epoch); #endif } /* * clock_select - find the pick-of-the-litter clock * * LOCKCLOCK: If the local clock is the prefer peer, it will always be * enabled, even if declared falseticker, (2) only the prefer peer can * be selected as the system peer, (3) if the external source is down, * the system leap bits are set to 11 and the stratum set to infinity. */ void clock_select(void) { struct peer *peer; int i, j, k, n; int nlist, nl3; double d, e, f; int allow, sw, osurv; double high, low; double synch[NTP_MAXCLOCK], error[NTP_MAXCLOCK]; struct peer *osys_peer; struct peer *typeacts = NULL; struct peer *typelocal = NULL; struct peer *typepps = NULL; struct peer *typesystem = NULL; static int list_alloc = 0; static struct endpoint *endpoint = NULL; static int *indx = NULL; static struct peer **peer_list = NULL; static u_int endpoint_size = 0; static u_int indx_size = 0; static u_int peer_list_size = 0; /* * Initialize and create endpoint, index and peer lists big * enough to handle all associations. */ osys_peer = sys_peer; sys_peer = NULL; osurv = sys_survivors; sys_survivors = 0; sys_prefer = NULL; #ifdef LOCKCLOCK sys_leap = LEAP_NOTINSYNC; sys_stratum = STRATUM_UNSPEC; memcpy(&sys_refid, "DOWN", 4); #endif /* LOCKCLOCK */ nlist = 0; for (n = 0; n < HASH_SIZE; n++) nlist += peer_hash_count[n]; if (nlist > list_alloc) { if (list_alloc > 0) { free(endpoint); free(indx); free(peer_list); } while (list_alloc < nlist) { list_alloc += 5; endpoint_size += 5 * 3 * sizeof(*endpoint); indx_size += 5 * 3 * sizeof(*indx); peer_list_size += 5 * sizeof(*peer_list); } endpoint = emalloc(endpoint_size); indx = emalloc(indx_size); peer_list = emalloc(peer_list_size); } /* * Initially, we populate the island with all the rifraff peers * that happen to be lying around. Those with seriously * defective clocks are immediately booted off the island. Then, * the falsetickers are culled and put to sea. The truechimers * remaining are subject to repeated rounds where the most * unpopular at each round is kicked off. When the population * has dwindled to sys_minclock, the survivors split a million * bucks and collectively crank the chimes. */ nlist = nl3 = 0; /* none yet */ for (n = 0; n < HASH_SIZE; n++) { for (peer = peer_hash[n]; peer != NULL; peer = peer->next) { peer->flags &= ~FLAG_SYSPEER; peer->status = CTL_PST_SEL_REJECT; /* * Leave the island immediately if the peer is * unfit to synchronize. */ if (peer_unfit(peer)) continue; /* * Don't allow the local clock or modem drivers * in the kitchen at this point, unless the * prefer peer. Do that later, but only if * nobody else is around. These guys are all * configured, so we never throw them away. */ if (peer->refclktype == REFCLK_LOCALCLOCK #if defined(VMS) && defined(VMS_LOCALUNIT) /* wjm: VMS_LOCALUNIT taken seriously */ && REFCLOCKUNIT(&peer->srcadr) != VMS_LOCALUNIT #endif /* VMS && VMS_LOCALUNIT */ ) { typelocal = peer; if (!(peer->flags & FLAG_PREFER)) continue; /* no local clock */ #ifdef LOCKCLOCK else sys_prefer = peer; #endif /* LOCKCLOCK */ } if (peer->sstclktype == CTL_SST_TS_TELEPHONE) { typeacts = peer; if (!(peer->flags & FLAG_PREFER)) continue; /* no acts */ } /* * If we get this far, the peer can stay on the * island, but does not yet have the immunity * idol. */ peer->status = CTL_PST_SEL_SANE; peer_list[nlist++] = peer; /* * Insert each interval endpoint on the sorted * list. */ e = peer->offset; /* Upper end */ f = root_distance(peer); e = e + f; for (i = nl3 - 1; i >= 0; i--) { if (e >= endpoint[indx[i]].val) break; indx[i + 3] = indx[i]; } indx[i + 3] = nl3; endpoint[nl3].type = 1; endpoint[nl3++].val = e; e = e - f; /* Center point */ for (; i >= 0; i--) { if (e >= endpoint[indx[i]].val) break; indx[i + 2] = indx[i]; } indx[i + 2] = nl3; endpoint[nl3].type = 0; endpoint[nl3++].val = e; e = e - f; /* Lower end */ for (; i >= 0; i--) { if (e >= endpoint[indx[i]].val) break; indx[i + 1] = indx[i]; } indx[i + 1] = nl3; endpoint[nl3].type = -1; endpoint[nl3++].val = e; } } #ifdef DEBUG if (debug > 2) for (i = 0; i < nl3; i++) printf("select: endpoint %2d %.6f\n", endpoint[indx[i]].type, endpoint[indx[i]].val); #endif /* * This is the actual algorithm that cleaves the truechimers * from the falsetickers. The original algorithm was described * in Keith Marzullo's dissertation, but has been modified for * better accuracy. * * Briefly put, we first assume there are no falsetickers, then * scan the candidate list first from the low end upwards and * then from the high end downwards. The scans stop when the * number of intersections equals the number of candidates less * the number of falsetickers. If this doesn't happen for a * given number of falsetickers, we bump the number of * falsetickers and try again. If the number of falsetickers * becomes equal to or greater than half the number of * candidates, the Albanians have won the Byzantine wars and * correct synchronization is not possible. * * Here, nlist is the number of candidates and allow is the * number of falsetickers. */ low = 1e9; high = -1e9; for (allow = 0; 2 * allow < nlist; allow++) { int found; /* * Bound the interval (low, high) as the largest * interval containing points from presumed truechimers. */ found = 0; n = 0; for (i = 0; i < nl3; i++) { low = endpoint[indx[i]].val; n -= endpoint[indx[i]].type; if (n >= nlist - allow) break; if (endpoint[indx[i]].type == 0) found++; } n = 0; for (j = nl3 - 1; j >= 0; j--) { high = endpoint[indx[j]].val; n += endpoint[indx[j]].type; if (n >= nlist - allow) break; if (endpoint[indx[j]].type == 0) found++; } /* * If the number of candidates found outside the * interval is greater than the number of falsetickers, * then at least one truechimer is outside the interval, * so go around again. This is what makes this algorithm * different than Marzullo's. */ if (found > allow) continue; /* * If an interval containing truechimers is found, stop. * If not, increase the number of falsetickers and go * around again. */ if (high > low) break; } /* * If no survivors remain at this point, check if the local * clock or modem drivers have been found. If so, nominate one * of them as the only survivor. Otherwise, give up and leave * the island to the rats. */ if (high <= low) { if (typeacts != 0) { typeacts->status = CTL_PST_SEL_SANE; peer_list[0] = typeacts; nlist = 1; } else if (typelocal != 0) { typelocal->status = CTL_PST_SEL_SANE; peer_list[0] = typelocal; nlist = 1; } else { if (osys_peer != NULL) { sys_poll = NTP_MINPOLL; NLOG(NLOG_SYNCSTATUS) msyslog(LOG_INFO, "no servers reachable"); report_event(EVNT_PEERSTCHG, NULL); } if (osurv > 0) resetmanycast(); return; } } /* * We can only trust the survivors if the number of candidates * sys_minsane is at least the number required to detect and * cast out one falsticker. For the Byzantine agreement * algorithm used here, that number is 4; however, the default * sys_minsane is 1 to speed initial synchronization. Careful * operators will tinker the value to 4 and use at least that * number of synchronization sources. */ if (nlist < sys_minsane) return; /* * Clustering algorithm. Construct candidate list in order first * by stratum then by root distance, but keep only the best * NTP_MAXCLOCK of them. Scan the list to find falsetickers, who * leave the island immediately. If a falseticker is not * configured, his association raft is drowned as well, but only * if at at least eight poll intervals have gone. We must leave * at least one peer to collect the million bucks. * * Note the hysteresis gimmick that increases the effective * distance for those rascals that have not made the final cut. * This is to discourage clockhopping. Note also the prejudice * against lower stratum peers if the floor is elevated. */ j = 0; for (i = 0; i < nlist; i++) { peer = peer_list[i]; if (nlist > 1 && (peer->offset <= low || peer->offset >= high)) { if (!(peer->flags & FLAG_CONFIG)) unpeer(peer); continue; } peer->status = CTL_PST_SEL_DISTSYSPEER; d = peer->stratum; if (d < sys_floor) d += sys_floor; if (d > sys_ceiling) d = STRATUM_UNSPEC; d = root_distance(peer) + d * MAXDISTANCE; d *= 1. - peer->hyst; if (j >= NTP_MAXCLOCK) { if (d >= synch[j - 1]) continue; else j--; } for (k = j; k > 0; k--) { if (d >= synch[k - 1]) break; peer_list[k] = peer_list[k - 1]; error[k] = error[k - 1]; synch[k] = synch[k - 1]; } peer_list[k] = peer; error[k] = peer->jitter; synch[k] = d; j++; } nlist = j; if (nlist == 0) { #ifdef DEBUG if (debug) printf("clock_select: empty intersection interval\n"); #endif return; } for (i = 0; i < nlist; i++) { peer_list[i]->status = CTL_PST_SEL_SELCAND; #ifdef DEBUG if (debug > 2) printf("select: %s distance %.6f jitter %.6f\n", ntoa(&peer_list[i]->srcadr), synch[i], SQRT(error[i])); #endif } /* * Now, vote outlyers off the island by select jitter weighted * by root dispersion. Continue voting as long as there are more * than sys_minclock survivors and the minimum select jitter * squared is greater than the maximum peer jitter squared. Stop * if we are about to discard a prefer peer, who of course has * the immunity idol. */ while (1) { d = 1e9; e = -1e9; k = 0; for (i = 0; i < nlist; i++) { if (error[i] < d) d = error[i]; f = 0; if (nlist > 1) { for (j = 0; j < nlist; j++) f += DIFF(peer_list[j]->offset, peer_list[i]->offset); f /= nlist - 1; } if (f * synch[i] > e) { sys_selerr = f; e = f * synch[i]; k = i; } } f = max(sys_selerr, SQUARE(LOGTOD(sys_precision))); if (nlist <= sys_minclock || f <= d || peer_list[k]->flags & FLAG_PREFER) break; #ifdef DEBUG if (debug > 2) printf( "select: drop %s select %.6f jitter %.6f\n", ntoa(&peer_list[k]->srcadr), SQRT(sys_selerr), SQRT(d)); #endif if (!(peer_list[k]->flags & FLAG_CONFIG) && peer_list[k]->hmode == MODE_CLIENT) unpeer(peer_list[k]); for (j = k + 1; j < nlist; j++) { peer_list[j - 1] = peer_list[j]; error[j - 1] = error[j]; } nlist--; } /* * What remains is a list usually not greater than sys_minclock * peers. We want only a peer at the lowest stratum to become * the system peer, although all survivors are eligible for the * combining algorithm. First record their order, diddle the * flags and clamp the poll intervals. Then, consider each peer * in turn and OR the leap bits on the assumption that, if some * of them honk nonzero bits, they must know what they are * doing. Check for prefer and pps peers at any stratum. Check * if the old system peer is among the peers at the lowest * stratum. Note that the head of the list is at the lowest * stratum and that unsynchronized peers cannot survive this * far. * * Fiddle for hysteresis. Pump it up for a peer only if the peer * stratum is at least the floor and there are enough survivors. * This minimizes the pain when tossing out rascals beneath the * floorboard. Don't count peers with stratum above the ceiling. * Manycast is sooo complicated. */ leap_consensus = 0; for (i = nlist - 1; i >= 0; i--) { peer = peer_list[i]; leap_consensus |= peer->leap; peer->status = CTL_PST_SEL_SYNCCAND; peer->rank++; peer->flags |= FLAG_SYSPEER; if (peer->stratum >= sys_floor && osurv >= sys_minclock) peer->hyst = HYST; else peer->hyst = 0; if (peer->stratum <= sys_ceiling) sys_survivors++; if (peer->flags & FLAG_PREFER) sys_prefer = peer; if (peer->refclktype == REFCLK_ATOM_PPS && peer->stratum < STRATUM_UNSPEC) typepps = peer; if (peer->stratum == peer_list[0]->stratum && peer == osys_peer) typesystem = peer; } /* * In manycast client mode we may have spooked a sizeable number * of peers that we don't need. If there are at least * sys_minclock of them, the manycast message will be turned * off. By the time we get here we nay be ready to prune some of * them back, but we want to make sure all the candicates have * had a chance. If they didn't pass the sanity and intersection * tests, they have already been voted off the island. */ if (sys_survivors < sys_minclock && osurv >= sys_minclock) resetmanycast(); /* * Mitigation rules of the game. There are several types of * peers that make a difference here: (1) prefer local peers * (type REFCLK_LOCALCLOCK with FLAG_PREFER) or prefer modem * peers (type REFCLK_NIST_ATOM etc with FLAG_PREFER), (2) pps * peers (type REFCLK_ATOM_PPS), (3) remaining prefer peers * (flag FLAG_PREFER), (4) the existing system peer, if any, (5) * the head of the survivor list. Note that only one peer can be * declared prefer. The order of preference is in the order * stated. Note that all of these must be at the lowest stratum, * i.e., the stratum of the head of the survivor list. */ if (sys_prefer) sw = sys_prefer->refclktype == REFCLK_LOCALCLOCK || sys_prefer->sstclktype == CTL_SST_TS_TELEPHONE || !typepps; else sw = 0; if (sw) { sys_peer = sys_prefer; sys_peer->status = CTL_PST_SEL_SYSPEER; sys_offset = sys_peer->offset; sys_syserr = sys_peer->jitter; #ifdef DEBUG if (debug > 1) printf("select: prefer offset %.6f\n", sys_offset); #endif } #ifndef LOCKCLOCK else if (typepps) { sys_peer = typepps; sys_peer->status = CTL_PST_SEL_PPS; sys_offset = sys_peer->offset; sys_syserr = sys_peer->jitter; if (!pps_control) NLOG(NLOG_SYSEVENT) msyslog(LOG_INFO, "pps sync enabled"); pps_control = current_time; #ifdef DEBUG if (debug > 1) printf("select: pps offset %.6f\n", sys_offset); #endif } else { if (typesystem) sys_peer = osys_peer; else sys_peer = peer_list[0]; sys_peer->status = CTL_PST_SEL_SYSPEER; sys_peer->rank++; sys_offset = clock_combine(peer_list, nlist); sys_syserr = sys_peer->jitter + sys_selerr; #ifdef DEBUG if (debug > 1) printf("select: combine offset %.6f\n", sys_offset); #endif } #endif /* LOCKCLOCK */ if (osys_peer != sys_peer) { char *src; if (sys_peer == NULL) sys_peer_refid = 0; else sys_peer_refid = addr2refid(&sys_peer->srcadr); report_event(EVNT_PEERSTCHG, NULL); #ifdef REFCLOCK if (ISREFCLOCKADR(&sys_peer->srcadr)) src = refnumtoa(&sys_peer->srcadr); else #endif src = ntoa(&sys_peer->srcadr); NLOG(NLOG_SYNCSTATUS) msyslog(LOG_INFO, "synchronized to %s, stratum=%d", src, sys_peer->stratum); } clock_update(); } /* * clock_combine - combine offsets from selected peers */ static double clock_combine( struct peer **peers, int npeers ) { int i; double x, y, z; y = z = 0; for (i = 0; i < npeers; i++) { x = root_distance(peers[i]); y += 1. / x; z += peers[i]->offset / x; } return (z / y); } /* * root_distance - compute synchronization distance from peer to root */ static double root_distance( struct peer *peer ) { /* * Careful squeak here. The value returned must be greater than * zero blamed on the peer jitter, which must be at least the * square of sys_precision. */ return ((peer->rootdelay + peer->delay) / 2 + peer->rootdispersion + peer->disp + clock_phi * (current_time - peer->update) + SQRT(peer->jitter)); } /* * peer_xmit - send packet for persistent association. */ static void peer_xmit( struct peer *peer /* peer structure pointer */ ) { struct pkt xpkt; /* transmit packet */ int sendlen, authlen; keyid_t xkeyid = 0; /* transmit key ID */ l_fp xmt_tx; /* * Initialize transmit packet header fields. */ xpkt.li_vn_mode = PKT_LI_VN_MODE(sys_leap, peer->version, peer->hmode); xpkt.stratum = STRATUM_TO_PKT(sys_stratum); xpkt.ppoll = peer->hpoll; xpkt.precision = sys_precision; xpkt.rootdelay = HTONS_FP(DTOFP(sys_rootdelay)); xpkt.rootdispersion = HTONS_FP(DTOUFP(sys_rootdispersion)); xpkt.refid = sys_refid; HTONL_FP(&sys_reftime, &xpkt.reftime); HTONL_FP(&peer->org, &xpkt.org); HTONL_FP(&peer->rec, &xpkt.rec); /* * If the received packet contains a MAC, the transmitted packet * is authenticated and contains a MAC. If not, the transmitted * packet is not authenticated. * * In the current I/O semantics the default interface is set * until after receiving a packet and setting the right * interface. So, the first packet goes out unauthenticated. * That's why the really icky test next is here. */ sendlen = LEN_PKT_NOMAC; if (!(peer->flags & FLAG_AUTHENABLE)) { get_systime(&peer->xmt); HTONL_FP(&peer->xmt, &xpkt.xmt); sendpkt(&peer->srcadr, peer->dstadr, sys_ttl[peer->ttl], &xpkt, sendlen); peer->sent++; #ifdef DEBUG if (debug) printf("transmit: at %ld %s->%s mode %d\n", current_time, stoa(&peer->dstadr->sin), stoa(&peer->srcadr), peer->hmode); #endif return; } /* * The received packet contains a MAC, so the transmitted packet * must be authenticated. If autokey is enabled, fuss with the * various modes; otherwise, private key cryptography is used. */ #ifdef OPENSSL if (crypto_flags && (peer->flags & FLAG_SKEY)) { struct exten *exten; /* extension field */ u_int opcode; /* * The Public Key Dance (PKD): Cryptographic credentials * are contained in extension fields, each including a * 4-octet length/code word followed by a 4-octet * association ID and optional additional data. Optional * data includes a 4-octet data length field followed by * the data itself. Request messages are sent from a * configured association; response messages can be sent * from a configured association or can take the fast * path without ever matching an association. Response * messages have the same code as the request, but have * a response bit and possibly an error bit set. In this * implementation, a message may contain no more than * one command and no more than one response. * * Cryptographic session keys include both a public and * a private componet. Request and response messages * using extension fields are always sent with the * private component set to zero. Packets without * extension fields indlude the private component when * the session key is generated. */ while (1) { /* * Allocate and initialize a keylist if not * already done. Then, use the list in inverse * order, discarding keys once used. Keep the * latest key around until the next one, so * clients can use client/server packets to * compute propagation delay. * * Note that once a key is used from the list, * it is retained in the key cache until the * next key is used. This is to allow a client * to retrieve the encrypted session key * identifier to verify authenticity. * * If for some reason a key is no longer in the * key cache, a birthday has happened and the * pseudo-random sequence is probably broken. In * that case, purge the keylist and regenerate * it. */ if (peer->keynumber == 0) make_keylist(peer, peer->dstadr); else peer->keynumber--; xkeyid = peer->keylist[peer->keynumber]; if (authistrusted(xkeyid)) break; else key_expire(peer); } peer->keyid = xkeyid; switch (peer->hmode) { /* * In broadcast server mode the autokey values are * required by the broadcast clients. Push them when a * new keylist is generated; otherwise, push the * association message so the client can request them at * other times. */ case MODE_BROADCAST: if (peer->flags & FLAG_ASSOC) exten = crypto_args(peer, CRYPTO_AUTO | CRYPTO_RESP, NULL); else exten = crypto_args(peer, CRYPTO_ASSOC | CRYPTO_RESP, NULL); sendlen += crypto_xmit(&xpkt, &peer->srcadr, sendlen, exten, 0); free(exten); break; /* * In symmetric modes the digest, certificate, agreement * parameters, cookie and autokey values are required. * The leapsecond table is optional. But, a passive peer * will not believe the active peer until the latter has * synchronized, so the agreement must be postponed * until then. In any case, if a new keylist is * generated, the autokey values are pushed. */ case MODE_ACTIVE: case MODE_PASSIVE: if (peer->cmmd != NULL) { peer->cmmd->associd = htonl(peer->associd); sendlen += crypto_xmit(&xpkt, &peer->srcadr, sendlen, peer->cmmd, 0); free(peer->cmmd); peer->cmmd = NULL; } exten = NULL; if (!peer->crypto) exten = crypto_args(peer, CRYPTO_ASSOC, sys_hostname); else if (!(peer->crypto & CRYPTO_FLAG_VALID)) exten = crypto_args(peer, CRYPTO_CERT, peer->issuer); /* * Identity. Note we have to sign the * certificate before the cookie to avoid a * deadlock when the passive peer is walking the * certificate trail. Awesome. */ else if ((opcode = crypto_ident(peer)) != 0) exten = crypto_args(peer, opcode, NULL); else if (sys_leap != LEAP_NOTINSYNC && !(peer->crypto & CRYPTO_FLAG_SIGN)) exten = crypto_args(peer, CRYPTO_SIGN, sys_hostname); /* * Autokey. We request the cookie only when the * server and client are synchronized and * signatures work both ways. On the other hand, * the active peer needs the autokey values * before then and when the passive peer is * waiting for the active peer to synchronize. * Any time we regenerate the key list, we offer * the autokey values without being asked. */ else if (sys_leap != LEAP_NOTINSYNC && peer->leap != LEAP_NOTINSYNC && !(peer->crypto & CRYPTO_FLAG_AGREE)) exten = crypto_args(peer, CRYPTO_COOK, NULL); else if (peer->flags & FLAG_ASSOC) exten = crypto_args(peer, CRYPTO_AUTO | CRYPTO_RESP, NULL); else if (!(peer->crypto & CRYPTO_FLAG_AUTO)) exten = crypto_args(peer, CRYPTO_AUTO, NULL); /* * Postamble. We trade leapseconds only when the * server and client are synchronized. */ else if (sys_leap != LEAP_NOTINSYNC && peer->leap != LEAP_NOTINSYNC && peer->crypto & CRYPTO_FLAG_TAI && !(peer->crypto & CRYPTO_FLAG_LEAP)) exten = crypto_args(peer, CRYPTO_TAI, NULL); if (exten != NULL) { sendlen += crypto_xmit(&xpkt, &peer->srcadr, sendlen, exten, 0); free(exten); } break; /* * In client mode the digest, certificate, agreement * parameters and cookie are required. The leapsecond * table is optional. If broadcast client mode, the * autokey values are required as well. In broadcast * client mode, these values must be acquired during the * client/server exchange to avoid having to wait until * the next key list regeneration. Otherwise, the poor * dude may die a lingering death until becoming * unreachable and attempting rebirth. * * If neither the server or client have the agreement * parameters, the protocol transmits the cookie in the * clear. If the server has the parameters, the client * requests them and the protocol blinds it using the * agreed key. It is a protocol error if the client has * the parameters but the server does not. */ case MODE_CLIENT: if (peer->cmmd != NULL) { peer->cmmd->associd = htonl(peer->associd); sendlen += crypto_xmit(&xpkt, &peer->srcadr, sendlen, peer->cmmd, 0); free(peer->cmmd); peer->cmmd = NULL; } exten = NULL; if (!peer->crypto) exten = crypto_args(peer, CRYPTO_ASSOC, sys_hostname); else if (!(peer->crypto & CRYPTO_FLAG_VALID)) exten = crypto_args(peer, CRYPTO_CERT, peer->issuer); /* * Identity. */ else if ((opcode = crypto_ident(peer)) != 0) exten = crypto_args(peer, opcode, NULL); /* * Autokey */ else if (!(peer->crypto & CRYPTO_FLAG_AGREE)) exten = crypto_args(peer, CRYPTO_COOK, NULL); else if (!(peer->crypto & CRYPTO_FLAG_AUTO) && (peer->cast_flags & MDF_BCLNT)) exten = crypto_args(peer, CRYPTO_AUTO, NULL); /* * Postamble. We can sign the certificate here, * since there is no chance of deadlock. */ else if (sys_leap != LEAP_NOTINSYNC && !(peer->crypto & CRYPTO_FLAG_SIGN)) exten = crypto_args(peer, CRYPTO_SIGN, sys_hostname); else if (sys_leap != LEAP_NOTINSYNC && peer->crypto & CRYPTO_FLAG_TAI && !(peer->crypto & CRYPTO_FLAG_LEAP)) exten = crypto_args(peer, CRYPTO_TAI, NULL); if (exten != NULL) { sendlen += crypto_xmit(&xpkt, &peer->srcadr, sendlen, exten, 0); free(exten); } break; } /* * If extension fields are present, we must use a * private value of zero and force min poll interval. * Most intricate. */ if (sendlen > LEN_PKT_NOMAC) session_key(&peer->dstadr->sin, &peer->srcadr, xkeyid, 0, 2); } #endif /* OPENSSL */ xkeyid = peer->keyid; get_systime(&peer->xmt); L_ADD(&peer->xmt, &sys_authdelay); HTONL_FP(&peer->xmt, &xpkt.xmt); authlen = authencrypt(xkeyid, (u_int32 *)&xpkt, sendlen); if (authlen == 0) { msyslog(LOG_INFO, "transmit: encryption key %d not found", xkeyid); if (peer->flags & FLAG_CONFIG) peer_clear(peer, "NKEY"); else unpeer(peer); return; } sendlen += authlen; #ifdef OPENSSL if (xkeyid > NTP_MAXKEY) authtrust(xkeyid, 0); #endif /* OPENSSL */ get_systime(&xmt_tx); if (sendlen > sizeof(xpkt)) { msyslog(LOG_ERR, "buffer overflow %u", sendlen); exit (-1); } sendpkt(&peer->srcadr, peer->dstadr, sys_ttl[peer->ttl], &xpkt, sendlen); /* * Calculate the encryption delay. Keep the minimum over * the latest two samples. */ L_SUB(&xmt_tx, &peer->xmt); L_ADD(&xmt_tx, &sys_authdelay); sys_authdly[1] = sys_authdly[0]; sys_authdly[0] = xmt_tx.l_uf; if (sys_authdly[0] < sys_authdly[1]) sys_authdelay.l_uf = sys_authdly[0]; else sys_authdelay.l_uf = sys_authdly[1]; peer->sent++; #ifdef OPENSSL #ifdef DEBUG if (debug) printf( "transmit: at %ld %s->%s mode %d keyid %08x len %d mac %d index %d\n", current_time, ntoa(&peer->dstadr->sin), ntoa(&peer->srcadr), peer->hmode, xkeyid, sendlen - authlen, authlen, peer->keynumber); #endif #else #ifdef DEBUG if (debug) printf( "transmit: at %ld %s->%s mode %d keyid %08x len %d mac %d\n", current_time, ntoa(&peer->dstadr->sin), ntoa(&peer->srcadr), peer->hmode, xkeyid, sendlen - authlen, authlen); #endif #endif /* OPENSSL */ } /* * fast_xmit - Send packet for nonpersistent association. Note that * neither the source or destination can be a broadcast address. */ static void fast_xmit( struct recvbuf *rbufp, /* receive packet pointer */ int xmode, /* transmit mode */ keyid_t xkeyid, /* transmit key ID */ int mask /* restrict mask */ ) { struct pkt xpkt; /* transmit packet structure */ struct pkt *rpkt; /* receive packet structure */ l_fp xmt_ts; /* timestamp */ l_fp xmt_tx; /* timestamp after authent */ int sendlen, authlen; #ifdef OPENSSL u_int32 temp32; #endif /* * Initialize transmit packet header fields from the receive * buffer provided. We leave some fields intact as received. If * the gazinta was from a multicast address, the gazouta must go * out another way. */ rpkt = &rbufp->recv_pkt; if (rbufp->dstadr->flags & INT_MULTICAST) rbufp->dstadr = findinterface(&rbufp->recv_srcadr); /* * If the packet has picked up a restriction due to either * access denied or rate exceeded, decide what to do with it. */ if (mask & (RES_DONTTRUST | RES_LIMITED)) { char *code = "????"; if (mask & RES_LIMITED) { sys_limitrejected++; code = "RATE"; } else if (mask & RES_DONTTRUST) { sys_restricted++; code = "DENY"; } /* * Here we light up a kiss-of-death packet. Note the * rate limit on these packets. Once a second initialize * a bucket counter. Every packet sent decrements the * counter until reaching zero. If the counter is zero, * drop the kod. */ if (sys_kod == 0 || !(mask & RES_DEMOBILIZE)) return; sys_kod--; memcpy(&xpkt.refid, code, 4); xpkt.li_vn_mode = PKT_LI_VN_MODE(LEAP_NOTINSYNC, PKT_VERSION(rpkt->li_vn_mode), xmode); xpkt.stratum = STRATUM_UNSPEC; } else { xpkt.li_vn_mode = PKT_LI_VN_MODE(sys_leap, PKT_VERSION(rpkt->li_vn_mode), xmode); xpkt.stratum = STRATUM_TO_PKT(sys_stratum); xpkt.refid = sys_refid; } xpkt.ppoll = rpkt->ppoll; xpkt.precision = sys_precision; xpkt.rootdelay = HTONS_FP(DTOFP(sys_rootdelay)); xpkt.rootdispersion = HTONS_FP(DTOUFP(sys_rootdispersion)); HTONL_FP(&sys_reftime, &xpkt.reftime); xpkt.org = rpkt->xmt; HTONL_FP(&rbufp->recv_time, &xpkt.rec); /* * If the received packet contains a MAC, the transmitted packet * is authenticated and contains a MAC. If not, the transmitted * packet is not authenticated. */ sendlen = LEN_PKT_NOMAC; if (rbufp->recv_length == sendlen) { get_systime(&xmt_ts); HTONL_FP(&xmt_ts, &xpkt.xmt); sendpkt(&rbufp->recv_srcadr, rbufp->dstadr, 0, &xpkt, sendlen); #ifdef DEBUG if (debug) printf("transmit: at %ld %s->%s mode %d\n", current_time, stoa(&rbufp->dstadr->sin), stoa(&rbufp->recv_srcadr), xmode); #endif return; } /* * The received packet contains a MAC, so the transmitted packet * must be authenticated. For private-key cryptography, use the * predefined private keys to generate the cryptosum. For * autokey cryptography, use the server private value to * generate the cookie, which is unique for every source- * destination-key ID combination. */ #ifdef OPENSSL if (xkeyid > NTP_MAXKEY) { keyid_t cookie; /* * The only way to get here is a reply to a legitimate * client request message, so the mode must be * MODE_SERVER. If an extension field is present, there * can be only one and that must be a command. Do what * needs, but with private value of zero so the poor * jerk can decode it. If no extension field is present, * use the cookie to generate the session key. */ cookie = session_key(&rbufp->recv_srcadr, &rbufp->dstadr->sin, 0, sys_private, 0); if (rbufp->recv_length >= (int)(sendlen + MAX_MAC_LEN + 2 * sizeof(u_int32))) { session_key(&rbufp->dstadr->sin, &rbufp->recv_srcadr, xkeyid, 0, 2); temp32 = CRYPTO_RESP; rpkt->exten[0] |= htonl(temp32); sendlen += crypto_xmit(&xpkt, &rbufp->recv_srcadr, sendlen, (struct exten *)rpkt->exten, cookie); } else { session_key(&rbufp->dstadr->sin, &rbufp->recv_srcadr, xkeyid, cookie, 2); } } #endif /* OPENSSL */ get_systime(&xmt_ts); L_ADD(&xmt_ts, &sys_authdelay); HTONL_FP(&xmt_ts, &xpkt.xmt); authlen = authencrypt(xkeyid, (u_int32 *)&xpkt, sendlen); sendlen += authlen; #ifdef OPENSSL if (xkeyid > NTP_MAXKEY) authtrust(xkeyid, 0); #endif /* OPENSSL */ get_systime(&xmt_tx); if (sendlen > sizeof(xpkt)) { msyslog(LOG_ERR, "buffer overflow %u", sendlen); exit (-1); } sendpkt(&rbufp->recv_srcadr, rbufp->dstadr, 0, &xpkt, sendlen); /* * Calculate the encryption delay. Keep the minimum over the * latest two samples. */ L_SUB(&xmt_tx, &xmt_ts); L_ADD(&xmt_tx, &sys_authdelay); sys_authdly[1] = sys_authdly[0]; sys_authdly[0] = xmt_tx.l_uf; if (sys_authdly[0] < sys_authdly[1]) sys_authdelay.l_uf = sys_authdly[0]; else sys_authdelay.l_uf = sys_authdly[1]; #ifdef DEBUG if (debug) printf( "transmit: at %ld %s->%s mode %d keyid %08x len %d mac %d\n", current_time, ntoa(&rbufp->dstadr->sin), ntoa(&rbufp->recv_srcadr), xmode, xkeyid, sendlen - authlen, authlen); #endif } #ifdef OPENSSL /* * key_expire - purge the key list */ void key_expire( struct peer *peer /* peer structure pointer */ ) { int i; if (peer->keylist != NULL) { for (i = 0; i <= peer->keynumber; i++) authtrust(peer->keylist[i], 0); free(peer->keylist); peer->keylist = NULL; } value_free(&peer->sndval); peer->keynumber = 0; #ifdef DEBUG if (debug) printf("key_expire: at %lu\n", current_time); #endif } #endif /* OPENSSL */ /* * Determine if the peer is unfit for synchronization * * A peer is unfit for synchronization if * > not reachable * > a synchronization loop would form * > never been synchronized * > stratum undefined or too high * > too long without synchronization * > designated noselect */ static int /* 0 if no, 1 if yes */ peer_unfit( struct peer *peer /* peer structure pointer */ ) { return (!peer->reach || (peer->stratum > 1 && peer->refid == peer->dstadr->addr_refid) || peer->leap == LEAP_NOTINSYNC || peer->stratum >= STRATUM_UNSPEC || root_distance(peer) >= MAXDISTANCE + 2. * clock_phi * ULOGTOD(sys_poll) || peer->flags & FLAG_NOSELECT ); } /* * Find the precision of this particular machine */ #define MINSTEP 100e-9 /* minimum clock increment (s) */ #define MAXSTEP 20e-3 /* maximum clock increment (s) */ #define MINLOOPS 5 /* minimum number of step samples */ /* * This routine calculates the system precision, defined as the minimum * of a sequency of differences between successive readings of the * system clock. However, if the system clock can be read more than once * during a tick interval, the difference can be zero or one LSB unit, * where the LSB corresponds to one nanosecond or one microsecond. * Conceivably, if some other process preempts this one and reads the * clock, the difference can be more than one LSB unit. * * For hardware clock frequencies of 10 MHz or less, we assume the * logical clock advances only at the hardware clock tick. For higher * frequencies, we assume the logical clock can advance no more than 100 * nanoseconds between ticks. */ int default_get_precision(void) { l_fp val; /* current seconds fraction */ l_fp last; /* last seconds fraction */ l_fp diff; /* difference */ double tick; /* computed tick value */ double dtemp; /* scratch */ int i; /* log2 precision */ /* * Loop to find tick value in nanoseconds. Toss out outlyer * values less than the minimun tick value. In wacky cases, use * the default maximum value. */ get_systime(&last); tick = MAXSTEP; for (i = 0; i < MINLOOPS;) { get_systime(&val); diff = val; L_SUB(&diff, &last); last = val; LFPTOD(&diff, dtemp); if (dtemp < MINSTEP) continue; i++; if (dtemp < tick) tick = dtemp; } /* * Find the nearest power of two. */ NLOG(NLOG_SYSEVENT) msyslog(LOG_INFO, "precision = %.3f usec", tick * 1e6); for (i = 0; tick <= 1; i++) tick *= 2; if (tick - 1. > 1. - tick / 2) i--; return (-i); } /* * kod_proto - called once per second to limit kiss-of-death packets */ void kod_proto(void) { sys_kod = sys_kod_rate; } /* * init_proto - initialize the protocol module's data */ void init_proto(void) { l_fp dummy; int i; /* * Fill in the sys_* stuff. Default is don't listen to * broadcasting, authenticate. */ sys_leap = LEAP_NOTINSYNC; sys_stratum = STRATUM_UNSPEC; memcpy(&sys_refid, "INIT", 4); sys_precision = (s_char)default_get_precision(); sys_jitter = LOGTOD(sys_precision); sys_rootdelay = 0; sys_rootdispersion = 0; L_CLR(&sys_reftime); sys_peer = NULL; sys_survivors = 0; get_systime(&dummy); sys_manycastserver = 0; sys_bclient = 0; sys_bdelay = DEFBROADDELAY; sys_calldelay = BURST_DELAY; sys_authenticate = 1; L_CLR(&sys_authdelay); sys_authdly[0] = sys_authdly[1] = 0; sys_stattime = 0; proto_clr_stats(); for (i = 0; i < MAX_TTL; i++) { sys_ttl[i] = (u_char)((i * 256) / MAX_TTL); sys_ttlmax = i; } #ifdef OPENSSL sys_automax = 1 << NTP_AUTOMAX; #endif /* OPENSSL */ /* * Default these to enable */ ntp_enable = 1; #ifndef KERNEL_FLL_BUG kern_enable = 1; #endif pps_enable = 0; stats_control = 1; } /* * proto_config - configure the protocol module */ void proto_config( int item, u_long value, double dvalue, struct sockaddr_storage* svalue ) { /* * Figure out what he wants to change, then do it */ switch (item) { /* * Turn on/off kernel discipline. */ case PROTO_KERNEL: kern_enable = (int)value; break; /* * Turn on/off clock discipline. */ case PROTO_NTP: ntp_enable = (int)value; break; /* * Turn on/off monitoring. */ case PROTO_MONITOR: if (value) mon_start(MON_ON); else mon_stop(MON_ON); break; /* * Turn on/off statistics. */ case PROTO_FILEGEN: stats_control = (int)value; break; /* * Turn on/off facility to listen to broadcasts. */ case PROTO_BROADCLIENT: sys_bclient = (int)value; if (value) io_setbclient(); else io_unsetbclient(); break; /* * Add muliticast group address. */ case PROTO_MULTICAST_ADD: if (svalue) io_multicast_add(*svalue); break; /* * Delete multicast group address. */ case PROTO_MULTICAST_DEL: if (svalue) io_multicast_del(*svalue); break; /* * Set default broadcast delay. */ case PROTO_BROADDELAY: sys_bdelay = dvalue; break; /* * Set modem call delay. */ case PROTO_CALLDELAY: sys_calldelay = (int)value; break; /* * Require authentication to mobilize ephemeral associations. */ case PROTO_AUTHENTICATE: sys_authenticate = (int)value; break; /* * Turn on/off PPS discipline. */ case PROTO_PPS: pps_enable = (int)value; break; /* * Set the minimum number of survivors. */ case PROTO_MINCLOCK: sys_minclock = (int)dvalue; break; /* * Set the minimum number of candidates. */ case PROTO_MINSANE: sys_minsane = (int)dvalue; break; /* * Set the stratum floor. */ case PROTO_FLOOR: sys_floor = (int)dvalue; break; /* * Set the stratum ceiling. */ case PROTO_CEILING: sys_ceiling = (int)dvalue; break; /* * Set the cohort switch. */ case PROTO_COHORT: sys_cohort= (int)dvalue; break; /* * Set the adjtime() resolution (s). */ case PROTO_ADJ: sys_tick = dvalue; break; #ifdef REFCLOCK /* * Turn on/off refclock calibrate */ case PROTO_CAL: cal_enable = (int)value; break; #endif default: /* * Log this error. */ msyslog(LOG_INFO, "proto_config: illegal item %d, value %ld", item, value); } } /* * proto_clr_stats - clear protocol stat counters */ void proto_clr_stats(void) { sys_stattime = current_time; sys_received = 0; sys_processed = 0; sys_newversionpkt = 0; sys_oldversionpkt = 0; sys_unknownversion = 0; sys_restricted = 0; sys_badlength = 0; sys_badauth = 0; sys_limitrejected = 0; }