1 /* $NetBSD: ntp_proto.c,v 1.21 2026/10/01 05:23:57 jnemeth Exp $ */ 2 3 /* 4 * ntp_proto.c - NTP version 4 protocol machinery 5 * 6 * ATTENTION: Get approval from Harlan on all changes to this file! 7 * (Harlan will be discussing these changes with Dave Mills.) 8 * 9 */ 10 #ifdef HAVE_CONFIG_H 11 #include <config.h> 12 #endif 13 14 #include "ntpd.h" 15 #include "ntp_stdlib.h" 16 #include "ntp_unixtime.h" 17 #include "ntp_control.h" 18 #include "ntp_string.h" 19 #include "ntp_leapsec.h" 20 #include "ntp_psl.h" 21 #include "refidsmear.h" 22 23 #include <stdio.h> 24 #ifdef HAVE_LIBSCF_H 25 #include <libscf.h> 26 #endif 27 #ifdef HAVE_UNISTD_H 28 #include <unistd.h> 29 #endif 30 31 /* [Bug 3031] define automatic broadcastdelay cutoff preset */ 32 #ifndef BDELAY_DEFAULT 33 # define BDELAY_DEFAULT (-0.050) 34 #endif 35 36 #define SRVFUZ_SHIFT 6 /* 64 seconds */ 37 #define SRVRSP_FUZZ(x) \ 38 do { \ 39 x.l_uf = 0; \ 40 x.l_ui &= ~((1 << SRVFUZ_SHIFT) - 1U); \ 41 } while (FALSE) 42 43 /* 44 * This macro defines the authentication state. If x is 1 authentication 45 * is required; otherwise it is optional. 46 */ 47 #define AUTH(x, y) ((x) ? (y) == AUTH_OK \ 48 : (y) == AUTH_OK || (y) == AUTH_NONE) 49 50 typedef enum 51 auth_state { 52 AUTH_UNKNOWN = -1, /* Unknown */ 53 AUTH_NONE, /* authentication not required */ 54 AUTH_OK, /* authentication OK */ 55 AUTH_ERROR, /* authentication error */ 56 AUTH_CRYPTO /* crypto_NAK */ 57 } auth_code; 58 59 /* 60 * Set up Kiss Code values 61 */ 62 63 typedef enum 64 kiss_codes { 65 NOKISS, /* No Kiss Code */ 66 RATEKISS, /* Rate limit Kiss Code */ 67 DENYKISS, /* Deny Kiss */ 68 RSTRKISS, /* Restricted Kiss */ 69 XKISS /* Experimental Kiss */ 70 } kiss_code; 71 72 typedef enum 73 nak_error_codes { 74 NONAK, /* No NAK seen */ 75 INVALIDNAK, /* NAK cannot be used */ 76 VALIDNAK /* NAK is valid */ 77 } nak_code; 78 79 /* 80 * traffic shaping parameters 81 */ 82 #define NTP_IBURST 6 /* packets in iburst */ 83 #define RESP_DELAY 1 /* refclock burst delay (s) */ 84 85 /* 86 * pool soliciting restriction duration (s) 87 */ 88 #define POOL_SOLICIT_WINDOW 8 89 90 /* 91 * flag bits propagated from pool/manycast to individual peers 92 */ 93 #define POOL_FLAG_PMASK (FLAG_IBURST | FLAG_NOSELECT) 94 95 /* 96 * peer_select groups statistics for a peer used by clock_select() and 97 * clock_cluster(). 98 */ 99 typedef struct peer_select_tag { 100 struct peer * peer; 101 double synch; /* sync distance */ 102 double error; /* jitter */ 103 double seljit; /* selection jitter */ 104 } peer_select; 105 106 /* 107 * System variables are declared here. Unless specified otherwise, all 108 * times are in seconds. 109 */ 110 u_char sys_leap; /* system leap indicator, use set_sys_leap() to change this */ 111 u_char xmt_leap; /* leap indicator sent in client requests, set up by set_sys_leap() */ 112 u_char sys_stratum; /* system stratum */ 113 s_char sys_precision; /* local clock precision (log2 s) */ 114 double sys_rootdelay; /* roundtrip delay to root (primary source) */ 115 double sys_rootdisp; /* dispersion to root (primary source) */ 116 double prev_rootdisp; /* previous root dispersion */ 117 double p2_rootdisp; /* previous previous root dispersion */ 118 u_int32 sys_refid; /* reference id (network byte order) */ 119 l_fp sys_reftime; /* last update time */ 120 l_fp prev_reftime; /* previous sys_reftime */ 121 l_fp p2_reftime; /* previous previous sys_reftime */ 122 u_long prev_time; /* "current_time" when saved prev_time */ 123 u_long p2_time; /* previous prev_time */ 124 struct peer *sys_peer; /* current peer */ 125 126 #ifdef LEAP_SMEAR 127 struct leap_smear_info leap_smear; 128 #endif 129 int leap_sec_in_progress; 130 131 /* 132 * Rate controls. Leaky buckets are used to throttle the packet 133 * transmission rates in order to protect busy servers such as at NIST 134 * and USNO. There is a counter for each association and another for KoD 135 * packets. The association counter decrements each second, but not 136 * below zero. Each time a packet is sent the counter is incremented by 137 * a configurable value representing the average interval between 138 * packets. A packet is delayed as long as the counter is greater than 139 * zero. Note this does not affect the time value computations. 140 */ 141 /* 142 * Nonspecified system state variables 143 */ 144 int sys_bclient; /* broadcast client enable */ 145 int sys_mclient; /* multicast client enable */ 146 double sys_bdelay; /* broadcast client default delay */ 147 int sys_authenticate; /* requre authentication for config */ 148 l_fp sys_authdelay; /* authentication delay */ 149 double sys_offset; /* current local clock offset */ 150 double sys_mindisp = MINDISPERSE; /* minimum distance (s) */ 151 double sys_maxdist = MAXDISTANCE; /* selection threshold */ 152 double sys_jitter; /* system jitter */ 153 u_long sys_epoch; /* last clock update time */ 154 static double sys_clockhop; /* clockhop threshold */ 155 static int leap_vote_ins; /* leap consensus for insert */ 156 static int leap_vote_del; /* leap consensus for delete */ 157 keyid_t sys_private; /* private value for session seed */ 158 int sys_manycastserver; /* respond to manycast client pkts */ 159 int ntp_mode7; /* respond to ntpdc (mode7) */ 160 int peer_ntpdate; /* active peers in ntpdate mode */ 161 int sys_survivors; /* truest of the truechimers */ 162 char *sys_ident = NULL; /* identity scheme */ 163 164 /* 165 * TOS and multicast mapping stuff 166 */ 167 int sys_floor = 0; /* cluster stratum floor */ 168 u_char sys_bcpollbstep = 0; /* Broadcast Poll backstep gate */ 169 int sys_ceiling = STRATUM_UNSPEC - 1; /* cluster stratum ceiling */ 170 int sys_minsane = 1; /* minimum candidates */ 171 int sys_minclock = NTP_MINCLOCK; /* minimum candidates */ 172 int sys_maxclock = NTP_MAXCLOCK; /* maximum candidates */ 173 int sys_cohort = 0; /* cohort switch */ 174 int sys_orphan = STRATUM_UNSPEC + 1; /* orphan stratum */ 175 int sys_orphwait = NTP_ORPHWAIT; /* orphan wait */ 176 int sys_beacon = BEACON; /* manycast beacon interval */ 177 u_int sys_ttlmax; /* max ttl mapping vector index */ 178 u_char sys_ttl[MAX_TTL]; /* ttl mapping vector */ 179 180 /* 181 * Statistics counters - first the good, then the bad 182 */ 183 u_long sys_stattime; /* elapsed time */ 184 u_long sys_received; /* packets received */ 185 u_long sys_processed; /* packets for this host */ 186 u_long sys_newversion; /* current version */ 187 u_long sys_oldversion; /* old version */ 188 u_long sys_restricted; /* access denied */ 189 u_long sys_badlength; /* bad length or format */ 190 u_long sys_badauth; /* bad authentication */ 191 u_long sys_declined; /* declined */ 192 u_long sys_limitrejected; /* rate exceeded */ 193 u_long sys_kodsent; /* KoD sent */ 194 195 /* 196 * Mechanism knobs: how soon do we peer_clear() or unpeer()? 197 * 198 * The default way is "on-receipt". If this was a packet from a 199 * well-behaved source, on-receipt will offer the fastest recovery. 200 * If this was from a DoS attack, the default way makes it easier 201 * for a bad-guy to DoS us. So look and see what bites you harder 202 * and choose according to your environment. 203 */ 204 int peer_clear_digest_early = 1; /* bad digest (TEST5) and Autokey */ 205 int unpeer_crypto_early = 1; /* bad crypto (TEST9) */ 206 int unpeer_crypto_nak_early = 1; /* crypto_NAK (TEST5) */ 207 int unpeer_digest_early = 1; /* bad digest (TEST5) */ 208 209 int dynamic_interleave = DYNAMIC_INTERLEAVE; /* Bug 2978 mitigation */ 210 211 int kiss_code_check(u_char hisleap, u_char hisstratum, u_char hismode, u_int32 refid); 212 nak_code valid_NAK (struct peer *peer, struct recvbuf *rbufp, u_char hismode); 213 static double root_distance (struct peer *); 214 static void clock_combine (peer_select *, int, int); 215 static void peer_xmit (struct peer *); 216 static void fast_xmit (struct recvbuf *, int, keyid_t, int); 217 static void pool_xmit (struct peer *); 218 static void clock_update (struct peer *); 219 static void measure_precision(void); 220 static double measure_tick_fuzz(void); 221 static int local_refid (struct peer *); 222 static int peer_unfit (struct peer *); 223 #ifdef AUTOKEY 224 static int group_test (char *, char *); 225 #endif /* AUTOKEY */ 226 #ifdef WORKER 227 void pool_name_resolved (int, int, void *, const char *, 228 const char *, const struct addrinfo *, 229 const struct addrinfo *); 230 #endif /* WORKER */ 231 232 const char * amtoa (int am); 233 234 235 void 236 set_sys_leap( 237 u_char new_sys_leap 238 ) 239 { 240 sys_leap = new_sys_leap; 241 xmt_leap = sys_leap; 242 243 /* 244 * Under certain conditions we send faked leap bits to clients, so 245 * eventually change xmt_leap below, but never change LEAP_NOTINSYNC. 246 */ 247 if (xmt_leap != LEAP_NOTINSYNC) { 248 if (leap_sec_in_progress) { 249 /* always send "not sync" */ 250 xmt_leap = LEAP_NOTINSYNC; 251 } 252 #ifdef LEAP_SMEAR 253 else { 254 /* 255 * If leap smear is enabled in general we must 256 * never send a leap second warning to clients, 257 * so make sure we only send "in sync". 258 */ 259 if (leap_smear.enabled) 260 xmt_leap = LEAP_NOWARNING; 261 } 262 #endif /* LEAP_SMEAR */ 263 } 264 } 265 266 267 /* 268 * Kiss Code check 269 */ 270 int 271 kiss_code_check( 272 u_char hisleap, 273 u_char hisstratum, 274 u_char hismode, 275 u_int32 refid 276 ) 277 { 278 279 if ( hismode == MODE_SERVER 280 && hisleap == LEAP_NOTINSYNC 281 && hisstratum == STRATUM_UNSPEC) { 282 if(memcmp(&refid,"RATE", 4) == 0) { 283 return (RATEKISS); 284 } else if(memcmp(&refid,"DENY", 4) == 0) { 285 return (DENYKISS); 286 } else if(memcmp(&refid,"RSTR", 4) == 0) { 287 return (RSTRKISS); 288 } else if(memcmp(&refid,"X", 1) == 0) { 289 return (XKISS); 290 } 291 } 292 return (NOKISS); 293 } 294 295 296 /* 297 * Check that NAK is valid 298 */ 299 nak_code 300 valid_NAK( 301 struct peer *peer, 302 struct recvbuf *rbufp, 303 u_char hismode 304 ) 305 { 306 int base_packet_length = MIN_V4_PKT_LEN; 307 int remainder_size; 308 struct pkt * rpkt; 309 int keyid; 310 l_fp p_org; /* origin timestamp */ 311 const l_fp * myorg; /* selected peer origin */ 312 313 /* 314 * Check to see if there is something beyond the basic packet 315 */ 316 if (rbufp->recv_length == base_packet_length) { 317 return NONAK; 318 } 319 320 remainder_size = rbufp->recv_length - base_packet_length; 321 /* 322 * Is this a potential NAK? 323 */ 324 if (remainder_size != 4) { 325 return NONAK; 326 } 327 328 /* 329 * Only server responses can contain NAK's 330 */ 331 332 if (hismode != MODE_SERVER && 333 hismode != MODE_ACTIVE && 334 hismode != MODE_PASSIVE 335 ) { 336 return INVALIDNAK; 337 } 338 339 /* 340 * Make sure that the extra field in the packet is all zeros 341 */ 342 rpkt = &rbufp->recv_pkt; 343 keyid = ntohl(((u_int32 *)rpkt)[base_packet_length / 4]); 344 if (keyid != 0) { 345 return INVALIDNAK; 346 } 347 348 /* 349 * During the first few packets of the autokey dance there will 350 * not (yet) be a keyid, but in this case FLAG_SKEY is set. 351 * So the NAK is invalid if either there's no peer, or 352 * if the keyid is 0 and FLAG_SKEY is not set. 353 */ 354 if (!peer || (!peer->keyid && !(peer->flags & FLAG_SKEY))) { 355 return INVALIDNAK; 356 } 357 358 /* 359 * The ORIGIN must match, or this cannot be a valid NAK, either. 360 */ 361 362 if (FLAG_LOOPNONCE & peer->flags) { 363 myorg = &peer->nonce; 364 } else { 365 if (peer->flip > 0) { 366 myorg = &peer->borg; 367 } else { 368 myorg = &peer->aorg; 369 } 370 } 371 372 NTOHL_FP(&rpkt->org, &p_org); 373 374 if (L_ISZERO(&p_org) || 375 L_ISZERO( myorg) || 376 !L_ISEQU(&p_org, myorg)) { 377 return INVALIDNAK; 378 } 379 380 /* If we ever passed all that checks, we should be safe. Well, 381 * as safe as we can ever be with an unauthenticated crypto-nak. 382 */ 383 return VALIDNAK; 384 } 385 386 387 /* 388 * transmit - transmit procedure called by poll timeout 389 */ 390 void 391 transmit( 392 struct peer *peer /* peer structure pointer */ 393 ) 394 { 395 u_char hpoll; 396 397 /* 398 * The polling state machine. There are two kinds of machines, 399 * those that never expect a reply (broadcast and manycast 400 * server modes) and those that do (all other modes). The dance 401 * is intricate... 402 */ 403 hpoll = peer->hpoll; 404 405 /* 406 * If we haven't received anything (even if unsync) since last 407 * send, reset ppoll. 408 */ 409 if (peer->outdate > peer->timelastrec && !peer->reach) 410 peer->ppoll = peer->maxpoll; 411 412 /* 413 * In broadcast mode the poll interval is never changed from 414 * minpoll. 415 */ 416 if (peer->cast_flags & (MDF_BCAST | MDF_MCAST)) { 417 peer->outdate = current_time; 418 poll_update(peer, hpoll, 0); 419 if (sys_leap != LEAP_NOTINSYNC) 420 peer_xmit(peer); 421 return; 422 } 423 424 /* 425 * In manycast mode we start with unity ttl. The ttl is 426 * increased by one for each poll until either sys_maxclock 427 * servers have been found or the maximum ttl is reached. When 428 * sys_maxclock servers are found we stop polling until one or 429 * more servers have timed out or until less than sys_minclock 430 * associations turn up. In this case additional better servers 431 * are dragged in and preempt the existing ones. Once every 432 * sys_beacon seconds we are to transmit unconditionally, but 433 * this code is not quite right -- peer->unreach counts polls 434 * and is being compared with sys_beacon, so the beacons happen 435 * every sys_beacon polls. 436 */ 437 if (peer->cast_flags & MDF_ACAST) { 438 peer->outdate = current_time; 439 poll_update(peer, hpoll, 0); 440 if (peer->unreach > sys_beacon) { 441 peer->unreach = 0; 442 peer->ttl = 0; 443 peer_xmit(peer); 444 } else if ( sys_survivors < sys_minclock 445 || peer_associations < sys_maxclock) { 446 if (peer->ttl < sys_ttlmax) 447 peer->ttl++; 448 peer_xmit(peer); 449 } 450 peer->unreach++; 451 return; 452 } 453 454 /* 455 * Pool associations transmit unicast solicitations when there 456 * are less than a hard limit of 2 * sys_maxclock associations, 457 * and either less than sys_minclock survivors or less than 458 * sys_maxclock associations. The hard limit prevents unbounded 459 * growth in associations if the system clock or network quality 460 * result in survivor count dipping below sys_minclock often. 461 * This was observed testing with pool, where sys_maxclock == 12 462 * resulted in 60 associations without the hard limit. A 463 * similar hard limit on manycastclient ephemeral associations 464 * may be appropriate. 465 */ 466 if (peer->cast_flags & MDF_POOL) { 467 peer->outdate = current_time; 468 poll_update(peer, hpoll, 0); 469 if ( (peer_associations <= 2 * sys_maxclock) 470 && ( peer_associations < sys_maxclock 471 || sys_survivors < sys_minclock)) 472 pool_xmit(peer); 473 return; 474 } 475 476 /* [Bug 3851] drop pool servers which can no longer be reached. */ 477 if (MDF_PCLNT & peer->cast_flags) { 478 if ( (IS_IPV6(&peer->srcadr) && !nonlocal_v6_addr_up) 479 || !nonlocal_v4_addr_up) { 480 unpeer(peer); 481 return; 482 } 483 } 484 485 /* 486 * In unicast modes the dance is much more intricate. It is 487 * designed to back off whenever possible to minimize network 488 * traffic. 489 */ 490 if (peer->burst == 0) { 491 u_char oreach; 492 493 /* 494 * Update the reachability status. If not heard for 495 * three consecutive polls, stuff infinity in the clock 496 * filter. 497 */ 498 oreach = peer->reach; 499 peer->outdate = current_time; 500 peer->unreach++; 501 peer->reach <<= 1; 502 if (!peer->reach) { 503 504 /* 505 * Here the peer is unreachable. If it was 506 * previously reachable raise a trap. Send a 507 * burst if enabled. 508 */ 509 clock_filter(peer, 0., 0., MAXDISPERSE); 510 if (oreach) { 511 peer_unfit(peer); 512 report_event(PEVNT_UNREACH, peer, NULL); 513 } 514 if ( (peer->flags & FLAG_IBURST) 515 && peer->retry == 0) 516 peer->retry = NTP_RETRY; 517 } else { 518 519 /* 520 * Here the peer is reachable. Send a burst if 521 * enabled and the peer is fit. Reset unreach 522 * for persistent and ephemeral associations. 523 * Unreach is also reset for survivors in 524 * clock_select(). 525 */ 526 hpoll = sys_poll; 527 if (!(peer->flags & FLAG_PREEMPT)) 528 peer->unreach = 0; 529 if ( (peer->flags & FLAG_BURST) 530 && peer->retry == 0 531 && !peer_unfit(peer)) 532 peer->retry = NTP_RETRY; 533 } 534 535 /* 536 * Watch for timeout. If ephemeral, toss the rascal; 537 * otherwise, bump the poll interval. Note the 538 * poll_update() routine will clamp it to maxpoll. 539 * If preemptible and we have more peers than maxclock, 540 * and this peer has the minimum score of preemptibles, 541 * demobilize. 542 */ 543 if (peer->unreach >= NTP_UNREACH) { 544 hpoll++; 545 /* ephemeral: no FLAG_CONFIG nor FLAG_PREEMPT */ 546 if (!(peer->flags & (FLAG_CONFIG | FLAG_PREEMPT))) { 547 report_event(PEVNT_RESTART, peer, "timeout"); 548 peer_clear(peer, "TIME"); 549 unpeer(peer); 550 return; 551 } 552 if ( (peer->flags & FLAG_PREEMPT) 553 && (peer_associations > sys_maxclock) 554 && score_all(peer)) { 555 report_event(PEVNT_RESTART, peer, "timeout"); 556 peer_clear(peer, "TIME"); 557 unpeer(peer); 558 return; 559 } 560 } 561 } else { 562 peer->burst--; 563 if (peer->burst == 0) { 564 565 /* 566 * If ntpdate mode and the clock has not been 567 * set and all peers have completed the burst, 568 * we declare a successful failure. 569 */ 570 if (mode_ntpdate) { 571 peer_ntpdate--; 572 if (peer_ntpdate == 0) { 573 msyslog(LOG_NOTICE, 574 "ntpd: no servers found"); 575 if (!msyslog_term) 576 printf( 577 "ntpd: no servers found\n"); 578 exit (0); 579 } 580 } 581 } 582 } 583 if (peer->retry > 0) 584 peer->retry--; 585 586 /* 587 * Do not transmit if in broadcast client mode. 588 */ 589 poll_update(peer, hpoll, (peer->hmode == MODE_CLIENT)); 590 if (peer->hmode != MODE_BCLIENT) 591 peer_xmit(peer); 592 593 return; 594 } 595 596 597 #ifdef DEBUG 598 const char * 599 amtoa( 600 int am 601 ) 602 { 603 char *bp; 604 605 switch(am) { 606 case AM_ERR: return "AM_ERR"; 607 case AM_NOMATCH: return "AM_NOMATCH"; 608 case AM_PROCPKT: return "AM_PROCPKT"; 609 case AM_BCST: return "AM_BCST"; 610 case AM_FXMIT: return "AM_FXMIT"; 611 case AM_MANYCAST: return "AM_MANYCAST"; 612 case AM_NEWPASS: return "AM_NEWPASS"; 613 case AM_NEWBCL: return "AM_NEWBCL"; 614 case AM_POSSBCL: return "AM_POSSBCL"; 615 default: 616 LIB_GETBUF(bp); 617 snprintf(bp, LIB_BUFLENGTH, "AM_#%d", am); 618 return bp; 619 } 620 } 621 #endif /* DEBUG */ 622 623 624 /* 625 * receive - receive procedure called for each packet received 626 */ 627 void 628 receive( 629 struct recvbuf *rbufp 630 ) 631 { 632 register struct peer *peer; /* peer structure pointer */ 633 register struct pkt *pkt; /* receive packet pointer */ 634 u_char hisversion; /* packet version */ 635 u_char hisleap; /* packet leap indicator */ 636 u_char hismode; /* packet mode */ 637 u_char hisstratum; /* packet stratum */ 638 r4addr r4a; /* address restrictions */ 639 u_short restrict_mask; /* restrict bits */ 640 const char *hm_str; /* hismode string */ 641 int kissCode = NOKISS; /* Kiss Code */ 642 int has_mac; /* length of MAC field */ 643 int authlen; /* offset of MAC field */ 644 auth_code is_authentic = AUTH_UNKNOWN; /* Was AUTH_NONE */ 645 nak_code crypto_nak_test; /* result of crypto-NAK check */ 646 int retcode = AM_NOMATCH; /* match code */ 647 keyid_t skeyid = 0; /* key IDs */ 648 u_int32 opcode = 0; /* extension field opcode */ 649 sockaddr_u *dstadr_sin; /* active runway */ 650 u_char cast_flags; /* MDF_* flags for newpeer() */ 651 struct peer *peer2; /* aux peer structure pointer */ 652 endpt *match_ep; /* newpeer() local address */ 653 l_fp p_org; /* origin timestamp */ 654 l_fp p_rec; /* receive timestamp */ 655 l_fp p_xmt; /* transmit timestamp */ 656 #ifdef DEBUG 657 const char *am_str; /* association match string */ 658 #endif 659 #ifdef AUTOKEY 660 char hostname[NTP_MAXSTRLEN + 1]; 661 char *groupname = NULL; 662 struct autokey *ap; /* autokey structure pointer */ 663 int rval; /* cookie snatcher */ 664 keyid_t pkeyid = 0, tkeyid = 0; /* key IDs */ 665 #endif /* AUTOKEY */ 666 #ifdef HAVE_NTP_SIGND 667 static unsigned char zero_key[16]; 668 #endif /* HAVE_NTP_SIGND */ 669 670 /* 671 * Note that there are many places we do not call record_raw_stats(). 672 * 673 * We only want to call it *after* we've sent a response, or perhaps 674 * when we've decided to drop a packet. 675 */ 676 677 /* 678 * Monitor the packet and get restrictions. Note that the packet 679 * length for control and private mode packets must be checked 680 * by the service routines. Some restrictions have to be handled 681 * later in order to generate a kiss-o'-death packet. 682 */ 683 /* 684 * Bogus port check is before anything, since it probably 685 * reveals a clogging attack. Likewise the mimimum packet size 686 * of 2 bytes (for mode 6/7) must be checked first. 687 */ 688 sys_received++; 689 if (0 == SRCPORT(&rbufp->recv_srcadr) || rbufp->recv_length < 2) { 690 sys_badlength++; 691 return; /* bogus port / length */ 692 } 693 restrictions(&rbufp->recv_srcadr, &r4a); 694 restrict_mask = r4a.rflags; 695 696 pkt = &rbufp->recv_pkt; 697 hisversion = PKT_VERSION(pkt->li_vn_mode); 698 hismode = (int)PKT_MODE(pkt->li_vn_mode); 699 700 if (restrict_mask & RES_IGNORE) { 701 DPRINTF(2, ("receive: drop: RES_IGNORE\n")); 702 sys_restricted++; 703 return; /* ignore everything */ 704 } 705 if (hismode == MODE_PRIVATE) { 706 if (!ntp_mode7 || (restrict_mask & RES_NOQUERY)) { 707 DPRINTF(2, ("receive: drop: !mode7 or RES_NOQUERY\n")); 708 sys_restricted++; 709 return; /* no query private */ 710 } 711 process_private(rbufp, !(RES_NOMODIFY & restrict_mask)); 712 return; 713 } 714 if (hismode == MODE_CONTROL) { 715 if (restrict_mask & RES_NOQUERY) { 716 DPRINTF(2, ("receive: drop: RES_NOQUERY\n")); 717 sys_restricted++; 718 return; /* no query control */ 719 } 720 process_control(rbufp, restrict_mask); 721 return; 722 } 723 if (restrict_mask & RES_DONTSERVE) { 724 DPRINTF(2, ("receive: drop: RES_DONTSERVE\n")); 725 sys_restricted++; 726 return; /* no time serve */ 727 } 728 729 730 /* If we arrive here, we should have a standard NTP packet. We 731 * check that the minimum size is available and fetch some more 732 * items from the packet once we can be sure they are indeed 733 * there. 734 */ 735 if ((size_t)rbufp->recv_length < LEN_PKT_NOMAC) { 736 sys_badlength++; 737 return; /* bogus length */ 738 } 739 740 hisleap = PKT_LEAP(pkt->li_vn_mode); 741 hisstratum = PKT_TO_STRATUM(pkt->stratum); 742 DEBUG_INSIST(0 != hisstratum); /* paranoia check PKT_TO_STRATUM result */ 743 /* TODO: this should be in a unit test */ 744 DPRINTF(1, ("receive: at %ld %s<-%s ippeerlimit %d mode %d iflags %s " 745 "restrict %s org 0x%x.%08x xmt 0x%x.%08x\n", 746 current_time, stoa(&rbufp->dstadr->sin), 747 stoa(&rbufp->recv_srcadr), r4a.ippeerlimit, hismode, 748 iflags_str(rbufp->dstadr->flags), 749 rflags_str(restrict_mask), 750 ntohl(pkt->org.l_ui), ntohl(pkt->org.l_uf), 751 ntohl(pkt->xmt.l_ui), ntohl(pkt->xmt.l_uf))); 752 753 /* 754 * This is for testing. If restricted drop ten percent of 755 * surviving packets. 756 */ 757 if (restrict_mask & RES_FLAKE) { 758 if (ntp_uurandom() < .1) { 759 DPRINTF(2, ("receive: drop: RES_FLAKE\n")); 760 sys_restricted++; 761 return; /* no flakeway */ 762 } 763 } 764 765 /* 766 ** Format Layer Checks 767 ** 768 ** Validate the packet format. The packet size, packet header, 769 ** and any extension field lengths are checked. We identify 770 ** the beginning of the MAC, to identify the upper limit of 771 ** of the hash computation. 772 ** 773 ** In case of a format layer check violation, the packet is 774 ** discarded with no further processing. 775 */ 776 777 /* 778 * Version check must be after the query packets, since they 779 * intentionally use an early version. 780 */ 781 if (hisversion == NTP_VERSION) { 782 sys_newversion++; /* new version */ 783 } else if ( !(restrict_mask & RES_VERSION) 784 && hisversion >= NTP_OLDVERSION) { 785 sys_oldversion++; /* previous version */ 786 } else { 787 DPRINTF(2, ("receive: drop: RES_VERSION\n")); 788 sys_badlength++; 789 return; /* old version */ 790 } 791 792 /* 793 * Figure out his mode and validate the packet. This has some 794 * legacy raunch that probably should be removed. In very early 795 * NTP versions mode 0 was equivalent to what later versions 796 * would interpret as client mode. 797 */ 798 if (hismode == MODE_UNSPEC) { 799 if (hisversion == NTP_OLDVERSION) { 800 hismode = MODE_CLIENT; 801 } else { 802 DPRINTF(2, ("receive: drop: MODE_UNSPEC\n")); 803 sys_badlength++; 804 return; /* invalid mode */ 805 } 806 } 807 808 /* 809 * Validate the poll interval in the packet. 810 * 0 probably indicates a data-minimized packet. 811 * A valid poll interval is required for RATEKISS, where 812 * a value of 0 is not allowed. We check for this below. 813 * 814 * There might be arguments against this check. If you have 815 * any of these arguments, please let us know. 816 * 817 * At this point, the packet cannot be a mode[67] packet. 818 */ 819 if ( pkt->ppoll 820 && ( (NTP_MINPOLL > pkt->ppoll) 821 || (NTP_MAXPOLL < pkt->ppoll) 822 ) 823 ) { 824 #ifdef BUG3870 825 DPRINTF(2, ("receive: drop: Invalid ppoll (%d) from %s\n", 826 pkt->ppoll, stoa(&rbufp->recv_srcadr))); 827 sys_badlength++; 828 return; /* invalid packet poll */ 829 #else 830 DPRINTF(2, ("receive: info: Invalid ppoll (%d) from %s\n", 831 pkt->ppoll, stoa(&rbufp->recv_srcadr))); 832 #endif 833 } 834 835 /* 836 * Parse the extension field if present. We figure out whether 837 * an extension field is present by measuring the MAC size. If 838 * the number of words following the packet header is 0, no MAC 839 * is present and the packet is not authenticated. If 1, the 840 * packet is a crypto-NAK; if 3, the packet is authenticated 841 * with DES; if 5, the packet is authenticated with MD5; if 6, 842 * the packet is authenticated with SHA. If 2 or * 4, the packet 843 * is a runt and discarded forthwith. If greater than 6, an 844 * extension field is present, so we subtract the length of the 845 * field and go around again. 846 * 847 * Note the above description is lame. We should/could also check 848 * the two bytes that make up the EF type and subtype, and then 849 * check the two bytes that tell us the EF length. A legacy MAC 850 * has a 4 byte keyID, and for conforming symmetric keys its value 851 * must be <= 64k, meaning the top two bytes will always be zero. 852 * Since the EF Type of 0 is reserved/unused, there's no way a 853 * conforming legacy MAC could ever be misinterpreted as an EF. 854 * 855 * There is more, but this isn't the place to document it. 856 */ 857 858 authlen = LEN_PKT_NOMAC; 859 has_mac = rbufp->recv_length - authlen; 860 while (has_mac > 0) { 861 u_int32 len; 862 #ifdef AUTOKEY 863 u_int32 hostlen; 864 struct exten *ep; 865 #endif /*AUTOKEY */ 866 867 if (has_mac % 4 != 0 || has_mac < (int)MIN_MAC_LEN) { 868 DPRINTF(2, ("receive: drop: bad post-packet length\n")); 869 sys_badlength++; 870 return; /* bad length */ 871 } 872 /* 873 * This next test is clearly wrong - it needlessly 874 * prohibits short EFs (which don't yet exist) 875 */ 876 if (has_mac <= (int)MAX_MAC_LEN) { 877 skeyid = ntohl(((u_int32 *)pkt)[authlen / 4]); 878 break; 879 880 } else { 881 opcode = ntohl(((u_int32 *)pkt)[authlen / 4]); 882 len = opcode & 0xffff; 883 if ( len % 4 != 0 884 || len < 4 885 || (int)len + authlen > rbufp->recv_length) { 886 DPRINTF(2, ("receive: drop: bad EF length\n")); 887 sys_badlength++; 888 return; /* bad length */ 889 } 890 #ifdef AUTOKEY 891 /* 892 * Extract calling group name for later. If 893 * sys_groupname is non-NULL, there must be 894 * a group name provided to elicit a response. 895 */ 896 if ( (opcode & 0x3fff0000) == CRYPTO_ASSOC 897 && sys_groupname != NULL) { 898 ep = (struct exten *)&((u_int32 *)pkt)[authlen / 4]; 899 hostlen = ntohl(ep->vallen); 900 if ( hostlen >= sizeof(hostname) 901 || hostlen > len - 902 offsetof(struct exten, pkt)) { 903 DPRINTF(2, ("receive: drop: bad autokey hostname length\n")); 904 sys_badlength++; 905 return; /* bad length */ 906 } 907 memcpy(hostname, &ep->pkt, hostlen); 908 hostname[hostlen] = '\0'; 909 groupname = strchr(hostname, '@'); 910 if (groupname == NULL) { 911 DPRINTF(2, ("receive: drop: empty autokey groupname\n")); 912 sys_declined++; 913 return; 914 } 915 groupname++; 916 } 917 #endif /* AUTOKEY */ 918 authlen += len; 919 has_mac -= len; 920 } 921 } 922 923 /* 924 * If has_mac is < 0 we had a malformed packet. 925 */ 926 if (has_mac < 0) { 927 DPRINTF(2, ("receive: drop: post-packet under-read\n")); 928 sys_badlength++; 929 return; /* bad length */ 930 } 931 932 /* 933 ** Packet Data Verification Layer 934 ** 935 ** This layer verifies the packet data content. If 936 ** authentication is required, a MAC must be present. 937 ** If a MAC is present, it must validate. 938 ** Crypto-NAK? Look - a shiny thing! 939 ** 940 ** If authentication fails, we're done. 941 */ 942 943 /* 944 * If authentication is explicitly required, a MAC must be present. 945 */ 946 if (restrict_mask & RES_DONTTRUST && has_mac == 0) { 947 DPRINTF(2, ("receive: drop: RES_DONTTRUST\n")); 948 sys_restricted++; 949 return; /* access denied */ 950 } 951 952 /* 953 * Update the MRU list and finger the cloggers. It can be a 954 * little expensive, so turn it off for production use. 955 * RES_LIMITED and RES_KOD will be cleared in the returned 956 * restrict_mask unless one or both actions are warranted. 957 */ 958 restrict_mask = ntp_monitor(rbufp, restrict_mask); 959 if (restrict_mask & RES_LIMITED) { 960 sys_limitrejected++; 961 if ( !(restrict_mask & RES_KOD) 962 || MODE_BROADCAST == hismode 963 || MODE_SERVER == hismode) { 964 if (MODE_SERVER == hismode) { 965 DPRINTF(1, ("Possibly self-induced rate limiting of MODE_SERVER from %s\n", 966 stoa(&rbufp->recv_srcadr))); 967 } else { 968 DPRINTF(2, ("receive: drop: RES_KOD\n")); 969 } 970 return; /* rate exceeded */ 971 } 972 if (hismode == MODE_CLIENT) { 973 fast_xmit(rbufp, MODE_SERVER, skeyid, 974 restrict_mask); 975 } else { 976 fast_xmit(rbufp, MODE_ACTIVE, skeyid, 977 restrict_mask); 978 } 979 return; /* rate exceeded */ 980 } 981 restrict_mask &= ~RES_KOD; 982 983 /* 984 * We have tossed out as many buggy packets as possible early in 985 * the game to reduce the exposure to a clogging attack. Now we 986 * have to burn some cycles to find the association and 987 * authenticate the packet if required. Note that we burn only 988 * digest cycles, again to reduce exposure. There may be no 989 * matching association and that's okay. 990 * 991 * More on the autokey mambo. Normally the local interface is 992 * found when the association was mobilized with respect to a 993 * designated remote address. We assume packets arriving from 994 * the remote address arrive via this interface and the local 995 * address used to construct the autokey is the unicast address 996 * of the interface. However, if the sender is a broadcaster, 997 * the interface broadcast address is used instead. 998 * Notwithstanding this technobabble, if the sender is a 999 * multicaster, the broadcast address is null, so we use the 1000 * unicast address anyway. Don't ask. 1001 */ 1002 1003 peer = findpeer(rbufp, hismode, &retcode); 1004 dstadr_sin = &rbufp->dstadr->sin; 1005 NTOHL_FP(&pkt->org, &p_org); 1006 NTOHL_FP(&pkt->rec, &p_rec); 1007 NTOHL_FP(&pkt->xmt, &p_xmt); 1008 hm_str = modetoa(hismode); 1009 #ifdef DEBUG 1010 am_str = amtoa(retcode); 1011 #endif 1012 1013 /* 1014 * Authentication is conditioned by three switches: 1015 * 1016 * NOPEER (RES_NOPEER) do not mobilize an association unless 1017 * authenticated 1018 * NOTRUST (RES_DONTTRUST) do not allow access unless 1019 * authenticated (implies NOPEER) 1020 * enable (sys_authenticate) master NOPEER switch, by default 1021 * on 1022 * 1023 * The NOPEER and NOTRUST can be specified on a per-client basis 1024 * using the restrict command. The enable switch if on implies 1025 * NOPEER for all clients. There are four outcomes: 1026 * 1027 * NONE The packet has no MAC. 1028 * OK the packet has a MAC and authentication succeeds 1029 * ERROR the packet has a MAC and authentication fails 1030 * CRYPTO crypto-NAK. The MAC has four octets only. 1031 * 1032 * Note: The AUTH(x, y) macro is used to filter outcomes. If x 1033 * is zero, acceptable outcomes of y are NONE and OK. If x is 1034 * one, the only acceptable outcome of y is OK. 1035 */ 1036 crypto_nak_test = valid_NAK(peer, rbufp, hismode); 1037 1038 /* 1039 * Drop any invalid crypto-NAKs 1040 */ 1041 if (crypto_nak_test == INVALIDNAK) { 1042 report_event(PEVNT_AUTH, peer, "Invalid_NAK"); 1043 if (0 != peer) { 1044 peer->badNAK++; 1045 } 1046 msyslog(LOG_ERR, "Invalid-NAK error at %ld %s<-%s", 1047 current_time, stoa(dstadr_sin), stoa(&rbufp->recv_srcadr)); 1048 return; 1049 } 1050 1051 if (has_mac == 0) { 1052 restrict_mask &= ~RES_MSSNTP; 1053 is_authentic = AUTH_NONE; /* not required */ 1054 DPRINTF(1, ("receive: at %ld %s<-%s mode %d/%s:%s len %d org 0x%x.%08x xmt 0x%x.%08x NOMAC\n", 1055 current_time, stoa(dstadr_sin), 1056 stoa(&rbufp->recv_srcadr), hismode, hm_str, am_str, 1057 authlen, 1058 ntohl(pkt->org.l_ui), ntohl(pkt->org.l_uf), 1059 ntohl(pkt->xmt.l_ui), ntohl(pkt->xmt.l_uf))); 1060 } else if (crypto_nak_test == VALIDNAK) { 1061 restrict_mask &= ~RES_MSSNTP; 1062 is_authentic = AUTH_CRYPTO; /* crypto-NAK */ 1063 DPRINTF(1, ("receive: at %ld %s<-%s mode %d/%s:%s keyid %08x len %d auth %d org 0x%x.%08x xmt 0x%x.%08x CRYPTONAK\n", 1064 current_time, stoa(dstadr_sin), 1065 stoa(&rbufp->recv_srcadr), hismode, hm_str, am_str, 1066 skeyid, authlen + has_mac, is_authentic, 1067 ntohl(pkt->org.l_ui), ntohl(pkt->org.l_uf), 1068 ntohl(pkt->xmt.l_ui), ntohl(pkt->xmt.l_uf))); 1069 1070 #ifdef HAVE_NTP_SIGND 1071 /* 1072 * If the signature is 20 bytes long, the last 16 of 1073 * which are zero, then this is a Microsoft client 1074 * wanting AD-style authentication of the server's 1075 * reply. 1076 * 1077 * This is described in Microsoft's WSPP docs, in MS-SNTP: 1078 * http://msdn.microsoft.com/en-us/library/cc212930.aspx 1079 */ 1080 } else if ( has_mac == MAX_MD5_LEN 1081 && (restrict_mask & RES_MSSNTP) 1082 && (retcode == AM_FXMIT || retcode == AM_NEWPASS) 1083 && (memcmp(zero_key, (char *)pkt + authlen + 4, 1084 MAX_MD5_LEN - 4) == 0)) { 1085 is_authentic = AUTH_NONE; 1086 DPRINTF(1, ("receive: at %ld %s<-%s mode %d/%s:%s len %d org %x.%08x xmt %x.%08x SIGND\n", 1087 current_time, stoa(dstadr_sin), 1088 stoa(&rbufp->recv_srcadr), hismode, hm_str, am_str, 1089 authlen, 1090 ntohl(pkt->org.l_ui), ntohl(pkt->org.l_uf), 1091 ntohl(pkt->xmt.l_ui), ntohl(pkt->xmt.l_uf))); 1092 #endif /* HAVE_NTP_SIGND */ 1093 1094 } else { 1095 /* 1096 * has_mac is not 0 1097 * Not a VALID_NAK 1098 * Not an MS-SNTP SIGND packet 1099 * 1100 * So there is a MAC here. 1101 */ 1102 1103 restrict_mask &= ~RES_MSSNTP; 1104 #ifdef AUTOKEY 1105 /* 1106 * For autokey modes, generate the session key 1107 * and install in the key cache. Use the socket 1108 * broadcast or unicast address as appropriate. 1109 */ 1110 if (crypto_flags && skeyid > NTP_MAXKEY) { 1111 1112 /* 1113 * More on the autokey dance (AKD). A cookie is 1114 * constructed from public and private values. 1115 * For broadcast packets, the cookie is public 1116 * (zero). For packets that match no 1117 * association, the cookie is hashed from the 1118 * addresses and private value. For server 1119 * packets, the cookie was previously obtained 1120 * from the server. For symmetric modes, the 1121 * cookie was previously constructed using an 1122 * agreement protocol; however, should PKI be 1123 * unavailable, we construct a fake agreement as 1124 * the EXOR of the peer and host cookies. 1125 * 1126 * hismode ephemeral persistent 1127 * ======================================= 1128 * active 0 cookie# 1129 * passive 0% cookie# 1130 * client sys cookie 0% 1131 * server 0% sys cookie 1132 * broadcast 0 0 1133 * 1134 * # if unsync, 0 1135 * % can't happen 1136 */ 1137 if (has_mac < (int)MAX_MD5_LEN) { 1138 DPRINTF(2, ("receive: drop: MD5 digest too short\n")); 1139 sys_badauth++; 1140 return; 1141 } 1142 if (hismode == MODE_BROADCAST) { 1143 1144 /* 1145 * For broadcaster, use the interface 1146 * broadcast address when available; 1147 * otherwise, use the unicast address 1148 * found when the association was 1149 * mobilized. However, if this is from 1150 * the wildcard interface, game over. 1151 */ 1152 if ( crypto_flags 1153 && rbufp->dstadr == 1154 ANY_INTERFACE_CHOOSE(&rbufp->recv_srcadr)) { 1155 DPRINTF(2, ("receive: drop: BCAST from wildcard\n")); 1156 sys_restricted++; 1157 return; /* no wildcard */ 1158 } 1159 pkeyid = 0; 1160 if (!SOCK_UNSPEC(&rbufp->dstadr->bcast)) 1161 dstadr_sin = 1162 &rbufp->dstadr->bcast; 1163 } else if (peer == NULL) { 1164 pkeyid = session_key( 1165 &rbufp->recv_srcadr, dstadr_sin, 0, 1166 sys_private, 0); 1167 } else { 1168 pkeyid = peer->pcookie; 1169 } 1170 1171 /* 1172 * The session key includes both the public 1173 * values and cookie. In case of an extension 1174 * field, the cookie used for authentication 1175 * purposes is zero. Note the hash is saved for 1176 * use later in the autokey mambo. 1177 */ 1178 if (authlen > (int)LEN_PKT_NOMAC && pkeyid != 0) { 1179 session_key(&rbufp->recv_srcadr, 1180 dstadr_sin, skeyid, 0, 2); 1181 tkeyid = session_key( 1182 &rbufp->recv_srcadr, dstadr_sin, 1183 skeyid, pkeyid, 0); 1184 } else { 1185 tkeyid = session_key( 1186 &rbufp->recv_srcadr, dstadr_sin, 1187 skeyid, pkeyid, 2); 1188 } 1189 1190 } 1191 #endif /* AUTOKEY */ 1192 1193 /* 1194 * Compute the cryptosum. Note a clogging attack may 1195 * succeed in bloating the key cache. If an autokey, 1196 * purge it immediately, since we won't be needing it 1197 * again. If the packet is authentic, it can mobilize an 1198 * association. Note that there is no key zero. 1199 */ 1200 if (!authdecrypt(skeyid, (u_int32 *)pkt, authlen, 1201 has_mac)) 1202 is_authentic = AUTH_ERROR; 1203 else 1204 is_authentic = AUTH_OK; 1205 #ifdef AUTOKEY 1206 if (crypto_flags && skeyid > NTP_MAXKEY) 1207 authtrust(skeyid, 0); 1208 #endif /* AUTOKEY */ 1209 DPRINTF(1, ("receive: at %ld %s<-%s mode %d/%s:%s keyid %08x len %d auth %d org 0x%x.%08x xmt 0x%x.%08x MAC\n", 1210 current_time, stoa(dstadr_sin), 1211 stoa(&rbufp->recv_srcadr), hismode, hm_str, am_str, 1212 skeyid, authlen + has_mac, is_authentic, 1213 ntohl(pkt->org.l_ui), ntohl(pkt->org.l_uf), 1214 ntohl(pkt->xmt.l_ui), ntohl(pkt->xmt.l_uf))); 1215 } 1216 1217 1218 /* 1219 * Bug 3454: 1220 * 1221 * Now come at this from a different perspective: 1222 * - If we expect a MAC and it's not there, we drop it. 1223 * - If we expect one keyID and get another, we drop it. 1224 * - If we have a MAC ahd it hasn't been validated yet, try. 1225 * - if the provided MAC doesn't validate, we drop it. 1226 * 1227 * There might be more to this. 1228 */ 1229 if (0 != peer && 0 != peer->keyid) { 1230 /* Should we msyslog() any of these? */ 1231 1232 /* 1233 * This should catch: 1234 * - no keyID where one is expected, 1235 * - different keyID than what we expect. 1236 */ 1237 if (peer->keyid != skeyid) { 1238 DPRINTF(2, ("receive: drop: Wanted keyID %d, got %d from %s\n", 1239 peer->keyid, skeyid, 1240 stoa(&rbufp->recv_srcadr))); 1241 sys_restricted++; 1242 return; /* drop: access denied */ 1243 } 1244 1245 /* 1246 * if has_mac != 0 ... 1247 * - If it has not yet been validated, do so. 1248 * (under what circumstances might that happen?) 1249 * - if missing or bad MAC, log and drop. 1250 */ 1251 if (0 != has_mac) { 1252 if (is_authentic == AUTH_UNKNOWN) { 1253 /* How can this happen? */ 1254 DPRINTF(2, ("receive: 3454 check: AUTH_UNKNOWN from %s\n", 1255 stoa(&rbufp->recv_srcadr))); 1256 if (!authdecrypt(skeyid, (u_int32 *)pkt, authlen, 1257 has_mac)) { 1258 /* MAC invalid or not found */ 1259 is_authentic = AUTH_ERROR; 1260 } else { 1261 is_authentic = AUTH_OK; 1262 } 1263 } 1264 if (is_authentic != AUTH_OK) { 1265 DPRINTF(2, ("receive: drop: missing or bad MAC from %s\n", 1266 stoa(&rbufp->recv_srcadr))); 1267 sys_restricted++; 1268 return; /* drop: access denied */ 1269 } 1270 } 1271 } 1272 /**/ 1273 1274 /* 1275 ** On-Wire Protocol Layer 1276 ** 1277 ** Verify protocol operations consistent with the on-wire protocol. 1278 ** The protocol discards bogus and duplicate packets as well as 1279 ** minimizes disruptions doe to protocol restarts and dropped 1280 ** packets. The operations are controlled by two timestamps: 1281 ** the transmit timestamp saved in the client state variables, 1282 ** and the origin timestamp in the server packet header. The 1283 ** comparison of these two timestamps is called the loopback test. 1284 ** The transmit timestamp functions as a nonce to verify that the 1285 ** response corresponds to the original request. The transmit 1286 ** timestamp also serves to discard replays of the most recent 1287 ** packet. Upon failure of either test, the packet is discarded 1288 ** with no further action. 1289 */ 1290 1291 /* 1292 * The association matching rules are implemented by a set of 1293 * routines and an association table. A packet matching an 1294 * association is processed by the peer process for that 1295 * association. If there are no errors, an ephemeral association 1296 * is mobilized: a broadcast packet mobilizes a broadcast client 1297 * aassociation; a manycast server packet mobilizes a manycast 1298 * client association; a symmetric active packet mobilizes a 1299 * symmetric passive association. 1300 */ 1301 DPRINTF(1, ("receive: MATCH_ASSOC dispatch: mode %d/%s:%s \n", 1302 hismode, hm_str, am_str)); 1303 switch (retcode) { 1304 1305 /* 1306 * This is a client mode packet not matching any association. If 1307 * an ordinary client, simply toss a server mode packet back 1308 * over the fence. If a manycast client, we have to work a 1309 * little harder. 1310 * 1311 * There are cases here where we do not call record_raw_stats(). 1312 */ 1313 case AM_FXMIT: 1314 1315 /* 1316 * If authentication OK, send a server reply; otherwise, 1317 * send a crypto-NAK. 1318 */ 1319 if (!(rbufp->dstadr->flags & INT_MCASTOPEN)) { 1320 /* HMS: would be nice to log FAST_XMIT|BADAUTH|RESTRICTED */ 1321 record_raw_stats(&rbufp->recv_srcadr, 1322 &rbufp->dstadr->sin, 1323 &p_org, &p_rec, &p_xmt, &rbufp->recv_time, 1324 PKT_LEAP(pkt->li_vn_mode), 1325 PKT_VERSION(pkt->li_vn_mode), 1326 PKT_MODE(pkt->li_vn_mode), 1327 PKT_TO_STRATUM(pkt->stratum), 1328 pkt->ppoll, 1329 pkt->precision, 1330 FPTOD(NTOHS_FP(pkt->rootdelay)), 1331 FPTOD(NTOHS_FP(pkt->rootdisp)), 1332 pkt->refid, 1333 rbufp->recv_length - MIN_V4_PKT_LEN, (u_char *)&pkt->exten); 1334 1335 if (AUTH(restrict_mask & RES_DONTTRUST, 1336 is_authentic)) { 1337 /* Bug 3596: Do we want to fuzz the reftime? */ 1338 fast_xmit(rbufp, MODE_SERVER, skeyid, 1339 restrict_mask); 1340 } else if (is_authentic == AUTH_ERROR) { 1341 /* Bug 3596: Do we want to fuzz the reftime? */ 1342 fast_xmit(rbufp, MODE_SERVER, 0, 1343 restrict_mask); 1344 sys_badauth++; 1345 } else { 1346 DPRINTF(2, ("receive: AM_FXMIT drop: !mcast restricted\n")); 1347 sys_restricted++; 1348 } 1349 1350 return; /* hooray */ 1351 } 1352 1353 /* 1354 * This must be manycast. Do not respond if not 1355 * configured as a manycast server. 1356 */ 1357 if (!sys_manycastserver) { 1358 DPRINTF(2, ("receive: AM_FXMIT drop: Not manycastserver\n")); 1359 sys_restricted++; 1360 return; /* not enabled */ 1361 } 1362 1363 #ifdef AUTOKEY 1364 /* 1365 * Do not respond if not the same group. 1366 */ 1367 if (group_test(groupname, NULL)) { 1368 DPRINTF(2, ("receive: AM_FXMIT drop: empty groupname\n")); 1369 sys_declined++; 1370 return; 1371 } 1372 #endif /* AUTOKEY */ 1373 1374 /* 1375 * Do not respond if we are not synchronized or our 1376 * stratum is greater than the manycaster or the 1377 * manycaster has already synchronized to us. 1378 */ 1379 if ( sys_leap == LEAP_NOTINSYNC 1380 || sys_stratum >= hisstratum 1381 || (!sys_cohort && sys_stratum == hisstratum + 1) 1382 || rbufp->dstadr->addr_refid == pkt->refid 1383 # ifdef WORDS_BIGENDIAN /* see local_refid() comment */ 1384 || ( IS_IPV6(&rbufp->dstadr->sin) 1385 &&rbufp->dstadr->old_refid == pkt->refid) 1386 # endif 1387 ) { 1388 DPRINTF(2, ("receive: sys leap: %0x, sys_stratum %d > hisstratum+1 %d, !sys_cohort %d && sys_stratum == hisstratum+1, loop refid %#x == pkt refid %#x\n", sys_leap, sys_stratum, hisstratum + 1, !sys_cohort, rbufp->dstadr->addr_refid, pkt->refid)); 1389 DPRINTF(2, ("receive: AM_FXMIT drop: LEAP_NOTINSYNC || stratum || loop\n")); 1390 sys_declined++; 1391 return; /* no help */ 1392 } 1393 1394 /* 1395 * Do not respond if the packet came into an IPv6 link-local 1396 * address on an interface where we also have a usable 1397 * global address, to avoid duplicate associations. 1398 */ 1399 if (INT_LL_OF_GLOB & rbufp->dstadr->flags) { 1400 DPRINTF(2, ("receive: declining manycast solicitation on link-local IPv6\n")); 1401 sys_declined++; 1402 return; 1403 } 1404 1405 /* 1406 * Respond only if authentication succeeds. Don't do a 1407 * crypto-NAK, as that would not be useful. 1408 */ 1409 if (AUTH(restrict_mask & RES_DONTTRUST, is_authentic)) { 1410 record_raw_stats(&rbufp->recv_srcadr, 1411 &rbufp->dstadr->sin, 1412 &p_org, &p_rec, &p_xmt, &rbufp->recv_time, 1413 PKT_LEAP(pkt->li_vn_mode), 1414 PKT_VERSION(pkt->li_vn_mode), 1415 PKT_MODE(pkt->li_vn_mode), 1416 PKT_TO_STRATUM(pkt->stratum), 1417 pkt->ppoll, 1418 pkt->precision, 1419 FPTOD(NTOHS_FP(pkt->rootdelay)), 1420 FPTOD(NTOHS_FP(pkt->rootdisp)), 1421 pkt->refid, 1422 rbufp->recv_length - MIN_V4_PKT_LEN, (u_char *)&pkt->exten); 1423 1424 /* Bug 3596: Do we want to fuzz the reftime? */ 1425 fast_xmit(rbufp, MODE_SERVER, skeyid, 1426 restrict_mask); 1427 } 1428 return; /* hooray */ 1429 1430 /* 1431 * This is a server mode packet returned in response to a client 1432 * mode packet sent to a multicast group address (for 1433 * manycastclient) or to a unicast address (for pool). The 1434 * origin timestamp is a good nonce to reliably associate the 1435 * reply with what was sent. If there is no match, that's 1436 * curious and could be an intruder attempting to clog, so we 1437 * just ignore it. 1438 * 1439 * If the packet is authentic and the manycastclient or pool 1440 * association is found, we mobilize a client association and 1441 * copy pertinent variables from the manycastclient or pool 1442 * association to the new client association. If not, just 1443 * ignore the packet. 1444 * 1445 * There is an implosion hazard at the manycast client, since 1446 * the manycast servers send the server packet immediately. If 1447 * the guy is already here, don't fire up a duplicate. 1448 * 1449 * There are cases here where we do not call record_raw_stats(). 1450 */ 1451 case AM_MANYCAST: 1452 1453 #ifdef AUTOKEY 1454 /* 1455 * Do not respond if not the same group. 1456 */ 1457 if (group_test(groupname, NULL)) { 1458 DPRINTF(2, ("receive: AM_MANYCAST drop: empty groupname\n")); 1459 sys_declined++; 1460 return; 1461 } 1462 #endif /* AUTOKEY */ 1463 /* Do not spin up duplicate manycast associations */ 1464 if (INT_LL_OF_GLOB & rbufp->dstadr->flags) { 1465 DPRINTF(2, ("receive: AM_MANYCAST drop: link-local server\n")); 1466 sys_declined++; 1467 return; 1468 } 1469 if ((peer2 = findmanycastpeer(rbufp)) == NULL) { 1470 DPRINTF(2, ("receive: AM_MANYCAST drop: No manycast peer\n")); 1471 sys_restricted++; 1472 return; /* not enabled */ 1473 } 1474 if (!AUTH( (!(peer2->cast_flags & MDF_POOL) 1475 && sys_authenticate) 1476 || (restrict_mask & (RES_NOPEER | 1477 RES_DONTTRUST)), is_authentic) 1478 /* MC: RES_NOEPEER? */ 1479 ) { 1480 DPRINTF(2, ("receive: AM_MANYCAST drop: bad auth || (NOPEER|DONTTRUST)\n")); 1481 sys_restricted++; 1482 return; /* access denied */ 1483 } 1484 1485 /* 1486 * Do not respond if unsynchronized or stratum is below 1487 * the floor or at or above the ceiling. 1488 */ 1489 if ( hisleap == LEAP_NOTINSYNC 1490 || hisstratum < sys_floor 1491 || hisstratum >= sys_ceiling) { 1492 DPRINTF(2, ("receive: AM_MANYCAST drop: unsync/stratum\n")); 1493 sys_declined++; 1494 return; /* no help */ 1495 } 1496 cast_flags = MDF_UCAST; 1497 if (MDF_POOL & peer2->cast_flags) { 1498 cast_flags |= MDF_PCLNT; 1499 } 1500 peer = newpeer(&rbufp->recv_srcadr, NULL, rbufp->dstadr, 1501 r4a.ippeerlimit, MODE_CLIENT, hisversion, 1502 peer2->minpoll, peer2->maxpoll, 1503 (FLAG_PREEMPT | (POOL_FLAG_PMASK & peer2->flags)), 1504 cast_flags, 0, skeyid, sys_ident); 1505 if (NULL == peer) { 1506 DPRINTF(2, ("receive: AM_MANYCAST drop: duplicate\n")); 1507 sys_declined++; 1508 return; /* ignore duplicate */ 1509 } 1510 1511 /* 1512 * After each ephemeral pool association is spun, 1513 * accelerate the next poll for the pool solicitor so 1514 * the pool will fill promptly. 1515 */ 1516 if (peer2->cast_flags & MDF_POOL) 1517 peer2->nextdate = current_time + 1; 1518 1519 /* 1520 * Further processing of the solicitation response would 1521 * simply detect its origin timestamp as bogus for the 1522 * brand-new association (it matches the prototype 1523 * association) and tinker with peer->nextdate delaying 1524 * first sync. 1525 */ 1526 return; /* solicitation response handled */ 1527 1528 /* 1529 * This is the first packet received from a broadcast server. If 1530 * the packet is authentic and we are enabled as broadcast 1531 * client, mobilize a broadcast client association. We don't 1532 * kiss any frogs here. 1533 * 1534 * There are cases here where we do not call record_raw_stats(). 1535 */ 1536 case AM_NEWBCL: 1537 1538 #ifdef AUTOKEY 1539 /* 1540 * Do not respond if not the same group. 1541 */ 1542 if (group_test(groupname, sys_ident)) { 1543 DPRINTF(2, ("receive: AM_NEWBCL drop: groupname mismatch\n")); 1544 sys_declined++; 1545 return; 1546 } 1547 #endif /* AUTOKEY */ 1548 if (!sys_bclient && !sys_mclient) { 1549 DPRINTF(2, ("receive: AM_NEWBCL drop: not a bclient/mclient\n")); 1550 sys_restricted++; 1551 return; /* not enabled */ 1552 } 1553 if (!AUTH(sys_authenticate | (restrict_mask & 1554 (RES_NOPEER | RES_DONTTRUST)), is_authentic) 1555 /* NEWBCL: RES_NOEPEER? */ 1556 ) { 1557 DPRINTF(2, ("receive: AM_NEWBCL drop: AUTH failed\n")); 1558 sys_restricted++; 1559 return; /* access denied */ 1560 } 1561 1562 /* 1563 * Do not respond if unsynchronized or stratum is below 1564 * the floor or at or above the ceiling. 1565 */ 1566 if ( hisleap == LEAP_NOTINSYNC 1567 || hisstratum < sys_floor 1568 || hisstratum >= sys_ceiling) { 1569 DPRINTF(2, ("receive: AM_NEWBCL drop: Unsync or bad stratum\n")); 1570 sys_declined++; 1571 return; /* no help */ 1572 } 1573 1574 #ifdef AUTOKEY 1575 /* 1576 * Do not respond if Autokey and the opcode is not a 1577 * CRYPTO_ASSOC response with association ID. 1578 */ 1579 if ( crypto_flags && skeyid > NTP_MAXKEY 1580 && (opcode & 0xffff0000) != (CRYPTO_ASSOC | CRYPTO_RESP)) { 1581 DPRINTF(2, ("receive: AM_NEWBCL drop: Autokey but not CRYPTO_ASSOC\n")); 1582 sys_declined++; 1583 return; /* protocol error */ 1584 } 1585 #endif /* AUTOKEY */ 1586 1587 /* 1588 * Broadcasts received via a multicast address may 1589 * arrive after a unicast volley has begun 1590 * with the same remote address. newpeer() will not 1591 * find duplicate associations on other local endpoints 1592 * if a non-NULL endpoint is supplied. multicastclient 1593 * ephemeral associations are unique across all local 1594 * endpoints. 1595 */ 1596 if (!(INT_MCASTOPEN & rbufp->dstadr->flags)) 1597 match_ep = rbufp->dstadr; 1598 else 1599 match_ep = NULL; 1600 1601 /* 1602 * Determine whether to execute the initial volley. 1603 */ 1604 if (sys_bdelay > 0.0) { 1605 #ifdef AUTOKEY 1606 /* 1607 * If a two-way exchange is not possible, 1608 * neither is Autokey. 1609 */ 1610 if (crypto_flags && skeyid > NTP_MAXKEY) { 1611 sys_restricted++; 1612 DPRINTF(2, ("receive: AM_NEWBCL drop: Autokey but not 2-way\n")); 1613 return; /* no autokey */ 1614 } 1615 #endif /* AUTOKEY */ 1616 1617 /* 1618 * Do not execute the volley. Start out in 1619 * broadcast client mode. 1620 */ 1621 peer = newpeer(&rbufp->recv_srcadr, NULL, match_ep, 1622 r4a.ippeerlimit, MODE_BCLIENT, hisversion, 1623 pkt->ppoll, pkt->ppoll, 1624 FLAG_PREEMPT, MDF_BCLNT, 0, skeyid, sys_ident); 1625 if (NULL == peer) { 1626 DPRINTF(2, ("receive: AM_NEWBCL drop: duplicate\n")); 1627 sys_restricted++; 1628 return; /* ignore duplicate */ 1629 1630 } else { 1631 peer->delay = sys_bdelay; 1632 peer->bxmt = p_xmt; 1633 } 1634 break; 1635 } 1636 1637 /* 1638 * Execute the initial volley in order to calibrate the 1639 * propagation delay and run the Autokey protocol. 1640 * 1641 * Note that the minpoll is taken from the broadcast 1642 * packet, normally 6 (64 s) and that the poll interval 1643 * is fixed at this value. 1644 */ 1645 peer = newpeer(&rbufp->recv_srcadr, NULL, match_ep, 1646 r4a.ippeerlimit, MODE_CLIENT, hisversion, 1647 pkt->ppoll, pkt->ppoll, 1648 FLAG_BC_VOL | FLAG_IBURST | FLAG_PREEMPT, MDF_BCLNT, 1649 0, skeyid, sys_ident); 1650 if (NULL == peer) { 1651 DPRINTF(2, ("receive: AM_NEWBCL drop: empty newpeer() failed\n")); 1652 sys_restricted++; 1653 return; /* ignore duplicate */ 1654 } 1655 peer->bxmt = p_xmt; 1656 #ifdef AUTOKEY 1657 if (skeyid > NTP_MAXKEY) 1658 crypto_recv(peer, rbufp); 1659 #endif /* AUTOKEY */ 1660 1661 return; /* hooray */ 1662 1663 /* 1664 * This is the first packet received from a potential ephemeral 1665 * symmetric active peer. First, deal with broken Windows clients. 1666 * Then, if NOEPEER is enabled, drop it. If the packet meets our 1667 * authenticty requirements and is the first he sent, mobilize 1668 * a passive association. 1669 * Otherwise, kiss the frog. 1670 * 1671 * There are cases here where we do not call record_raw_stats(). 1672 */ 1673 case AM_NEWPASS: 1674 1675 DEBUG_REQUIRE(MODE_ACTIVE == hismode); 1676 1677 #ifdef AUTOKEY 1678 /* 1679 * Do not respond if not the same group. 1680 */ 1681 if (group_test(groupname, sys_ident)) { 1682 DPRINTF(2, ("receive: AM_NEWPASS drop: Autokey group mismatch\n")); 1683 sys_declined++; 1684 return; 1685 } 1686 #endif /* AUTOKEY */ 1687 if (!AUTH(sys_authenticate | (restrict_mask & 1688 (RES_NOPEER | RES_DONTTRUST)), is_authentic) 1689 ) { 1690 /* 1691 * If authenticated but cannot mobilize an 1692 * association, send a symmetric passive 1693 * response without mobilizing an association. 1694 * This is for drat broken Windows clients. See 1695 * Microsoft KB 875424 for preferred workaround. 1696 */ 1697 if (AUTH(restrict_mask & RES_DONTTRUST, 1698 is_authentic)) { 1699 fast_xmit(rbufp, MODE_PASSIVE, skeyid, 1700 restrict_mask); 1701 return; /* hooray */ 1702 } 1703 /* HMS: Why is this next set of lines a feature? */ 1704 if (is_authentic == AUTH_ERROR) { 1705 fast_xmit(rbufp, MODE_PASSIVE, 0, 1706 restrict_mask); 1707 sys_restricted++; 1708 return; 1709 } 1710 1711 if (restrict_mask & RES_NOEPEER) { 1712 DPRINTF(2, ("receive: AM_NEWPASS drop: NOEPEER\n")); 1713 sys_declined++; 1714 return; 1715 } 1716 1717 /* [Bug 2941] 1718 * If we got here, the packet isn't part of an 1719 * existing association, either isn't correctly 1720 * authenticated or it is but we are refusing 1721 * ephemeral peer requests, and it didn't meet 1722 * either of the previous two special cases so we 1723 * should just drop it on the floor. For example, 1724 * crypto-NAKs (is_authentic == AUTH_CRYPTO) 1725 * will make it this far. This is just 1726 * debug-printed and not logged to avoid log 1727 * flooding. 1728 */ 1729 DPRINTF(2, ("receive: at %ld refusing to mobilize passive association" 1730 " with unknown peer %s mode %d/%s:%s keyid %08x len %d auth %d\n", 1731 current_time, stoa(&rbufp->recv_srcadr), 1732 hismode, hm_str, am_str, skeyid, 1733 (authlen + has_mac), is_authentic)); 1734 sys_declined++; 1735 return; 1736 } 1737 1738 if (restrict_mask & RES_NOEPEER) { 1739 DPRINTF(2, ("receive: AM_NEWPASS drop: NOEPEER\n")); 1740 sys_declined++; 1741 return; 1742 } 1743 1744 /* 1745 * Do not respond if synchronized and if stratum is 1746 * below the floor or at or above the ceiling. Note, 1747 * this allows an unsynchronized peer to synchronize to 1748 * us. It would be very strange if he did and then was 1749 * nipped, but that could only happen if we were 1750 * operating at the top end of the range. It also means 1751 * we will spin an ephemeral association in response to 1752 * MODE_ACTIVE KoDs, which will time out eventually. 1753 */ 1754 if ( hisleap != LEAP_NOTINSYNC 1755 && (hisstratum < sys_floor || hisstratum >= sys_ceiling)) { 1756 DPRINTF(2, ("receive: AM_NEWPASS drop: Remote stratum (%d) out of range\n", 1757 hisstratum)); 1758 sys_declined++; 1759 return; /* no help */ 1760 } 1761 1762 /* 1763 * The message is correctly authenticated and allowed. 1764 * Mobilize a symmetric passive association, if we won't 1765 * exceed the ippeerlimit. 1766 */ 1767 if ((peer = newpeer(&rbufp->recv_srcadr, NULL, rbufp->dstadr, 1768 r4a.ippeerlimit, MODE_PASSIVE, hisversion, 1769 pkt->ppoll, NTP_MAXDPOLL, 0, MDF_UCAST, 0, 1770 skeyid, sys_ident)) == NULL) { 1771 DPRINTF(2, ("receive: AM_NEWPASS drop: newpeer() failed\n")); 1772 sys_declined++; 1773 return; /* ignore duplicate */ 1774 } 1775 break; 1776 1777 1778 /* 1779 * Process regular packet. Nothing special. 1780 * 1781 * There are cases here where we do not call record_raw_stats(). 1782 */ 1783 case AM_PROCPKT: 1784 1785 #ifdef AUTOKEY 1786 /* 1787 * Do not respond if not the same group. 1788 */ 1789 if (group_test(groupname, peer->ident)) { 1790 DPRINTF(2, ("receive: AM_PROCPKT drop: Autokey group mismatch\n")); 1791 sys_declined++; 1792 return; 1793 } 1794 #endif /* AUTOKEY */ 1795 1796 if (MODE_BROADCAST == hismode) { 1797 int bail = 0; 1798 l_fp tdiff; 1799 u_long deadband; 1800 1801 DPRINTF(2, ("receive: PROCPKT/BROADCAST: prev pkt %ld seconds ago, ppoll: %d, %d secs\n", 1802 (current_time - peer->timelastrec), 1803 peer->ppoll, (1 << peer->ppoll) 1804 )); 1805 /* Things we can check: 1806 * 1807 * Did the poll interval change? 1808 * Is the poll interval in the packet in-range? 1809 * Did this packet arrive too soon? 1810 * Is the timestamp in this packet monotonic 1811 * with respect to the previous packet? 1812 */ 1813 1814 /* This is noteworthy, not error-worthy */ 1815 if (pkt->ppoll != peer->ppoll) { 1816 msyslog(LOG_INFO, "receive: broadcast poll from %s changed from %u to %u", 1817 stoa(&rbufp->recv_srcadr), 1818 peer->ppoll, pkt->ppoll); 1819 } 1820 1821 /* This is error-worthy */ 1822 if ( pkt->ppoll < peer->minpoll 1823 || pkt->ppoll > peer->maxpoll) { 1824 msyslog(LOG_INFO, "receive: broadcast poll of %u from %s is out-of-range (%d to %d)!", 1825 pkt->ppoll, stoa(&rbufp->recv_srcadr), 1826 peer->minpoll, peer->maxpoll); 1827 ++bail; 1828 } 1829 1830 /* too early? worth an error, too! 1831 * 1832 * [Bug 3113] Ensure that at least one poll 1833 * interval has elapsed since the last **clean** 1834 * packet was received. We limit the check to 1835 * **clean** packets to prevent replayed packets 1836 * and incorrectly authenticated packets, which 1837 * we'll discard, from being used to create a 1838 * denial of service condition. 1839 */ 1840 deadband = (1u << pkt->ppoll); 1841 if (FLAG_BC_VOL & peer->flags) 1842 deadband -= 3; /* allow greater fuzz after volley */ 1843 if ((current_time - peer->timereceived) < deadband) { 1844 msyslog(LOG_INFO, "receive: broadcast packet from %s arrived after %lu, not %lu seconds!", 1845 stoa(&rbufp->recv_srcadr), 1846 (current_time - peer->timereceived), 1847 deadband); 1848 ++bail; 1849 } 1850 1851 /* Alert if time from the server is non-monotonic. 1852 * 1853 * [Bug 3114] is about Broadcast mode replay DoS. 1854 * 1855 * Broadcast mode *assumes* a trusted network. 1856 * Even so, it's nice to be robust in the face 1857 * of attacks. 1858 * 1859 * If we get an authenticated broadcast packet 1860 * with an "earlier" timestamp, it means one of 1861 * two things: 1862 * 1863 * - the broadcast server had a backward step. 1864 * 1865 * - somebody is trying a replay attack. 1866 * 1867 * deadband: By default, we assume the broadcast 1868 * network is trustable, so we take our accepted 1869 * broadcast packets as we receive them. But 1870 * some folks might want to take additional poll 1871 * delays before believing a backward step. 1872 */ 1873 if (sys_bcpollbstep) { 1874 /* pkt->ppoll or peer->ppoll ? */ 1875 deadband = (1u << pkt->ppoll) 1876 * sys_bcpollbstep + 2; 1877 } else { 1878 deadband = 0; 1879 } 1880 1881 if (L_ISZERO(&peer->bxmt)) { 1882 tdiff.l_ui = tdiff.l_uf = 0; 1883 } else { 1884 tdiff = p_xmt; 1885 L_SUB(&tdiff, &peer->bxmt); 1886 } 1887 if ( tdiff.l_i < 0 1888 && (current_time - peer->timereceived) < deadband) 1889 { 1890 msyslog(LOG_INFO, "receive: broadcast packet from %s contains non-monotonic timestamp: 0x%x.%08x -> 0x%x.%08x", 1891 stoa(&rbufp->recv_srcadr), 1892 peer->bxmt.l_ui, peer->bxmt.l_uf, 1893 p_xmt.l_ui, p_xmt.l_uf 1894 ); 1895 ++bail; 1896 } 1897 1898 if (bail) { 1899 DPRINTF(2, ("receive: AM_PROCPKT drop: bail\n")); 1900 peer->timelastrec = current_time; 1901 sys_declined++; 1902 return; 1903 } 1904 } 1905 1906 break; 1907 1908 /* 1909 * A passive packet matches a passive association. This is 1910 * usually the result of reconfiguring a client on the fly. As 1911 * this association might be legitimate and this packet an 1912 * attempt to deny service, just ignore it. 1913 */ 1914 case AM_ERR: 1915 DPRINTF(2, ("receive: AM_ERR drop.\n")); 1916 sys_declined++; 1917 return; 1918 1919 /* 1920 * For everything else there is the bit bucket. 1921 */ 1922 default: 1923 DPRINTF(2, ("receive: default drop.\n")); 1924 sys_declined++; 1925 return; 1926 } 1927 1928 #ifdef AUTOKEY 1929 /* 1930 * If the association is configured for Autokey, the packet must 1931 * have a public key ID; if not, the packet must have a 1932 * symmetric key ID. 1933 */ 1934 if ( is_authentic != AUTH_CRYPTO 1935 && ( ((peer->flags & FLAG_SKEY) && skeyid <= NTP_MAXKEY) 1936 || (!(peer->flags & FLAG_SKEY) && skeyid > NTP_MAXKEY))) { 1937 DPRINTF(2, ("receive: drop: Autokey but wrong/bad auth\n")); 1938 sys_badauth++; 1939 return; 1940 } 1941 #endif /* AUTOKEY */ 1942 1943 peer->received++; 1944 peer->flash &= ~PKT_TEST_MASK; 1945 if (peer->flags & FLAG_XBOGUS) { 1946 peer->flags &= ~FLAG_XBOGUS; 1947 peer->flash |= TEST3; 1948 } 1949 1950 /* 1951 * Next comes a rigorous schedule of timestamp checking. If the 1952 * transmit timestamp is zero, the server has not initialized in 1953 * interleaved modes or is horribly broken. 1954 * 1955 * A KoD packet we pay attention to cannot have a 0 transmit 1956 * timestamp. 1957 */ 1958 1959 kissCode = kiss_code_check(hisleap, hisstratum, hismode, pkt->refid); 1960 1961 if (L_ISZERO(&p_xmt)) { 1962 peer->flash |= TEST3; /* unsynch */ 1963 if (kissCode != NOKISS) { /* KoD packet */ 1964 peer->bogusorg++; /* for TEST2 or TEST3 */ 1965 msyslog(LOG_INFO, 1966 "receive: Unexpected zero transmit timestamp in KoD from %s", 1967 ntoa(&peer->srcadr)); 1968 return; 1969 } 1970 1971 /* 1972 * If the transmit timestamp duplicates our previous one, the 1973 * packet is a replay. This prevents the bad guys from replaying 1974 * the most recent packet, authenticated or not. 1975 */ 1976 } else if ( ((FLAG_LOOPNONCE & peer->flags) && L_ISEQU(&peer->nonce, &p_xmt)) 1977 || (!(FLAG_LOOPNONCE & peer->flags) && L_ISEQU(&peer->xmt, &p_xmt)) 1978 ) { 1979 DPRINTF(2, ("receive: drop: Duplicate xmit\n")); 1980 peer->flash |= TEST1; /* duplicate */ 1981 peer->oldpkt++; 1982 return; 1983 1984 /* 1985 * If this is a broadcast mode packet, make sure hisstratum 1986 * is appropriate. Don't do anything else here - we wait to 1987 * see if this is an interleave broadcast packet until after 1988 * we've validated the MAC that SHOULD be provided. 1989 * 1990 * hisstratum cannot be 0 - see assertion above. 1991 * If hisstratum is 15, then we'll advertise as UNSPEC but 1992 * at least we'll be able to sync with the broadcast server. 1993 */ 1994 } else if (hismode == MODE_BROADCAST) { 1995 /* 0 is unexpected too, and impossible */ 1996 if (STRATUM_UNSPEC <= hisstratum) { 1997 /* Is this a ++sys_declined or ??? */ 1998 msyslog(LOG_INFO, 1999 "receive: Unexpected stratum (%d) in broadcast from %s", 2000 hisstratum, ntoa(&peer->srcadr)); 2001 return; 2002 } 2003 2004 /* 2005 * Basic KoD validation checking: 2006 * 2007 * KoD packets are a mixed-blessing. Forged KoD packets 2008 * are DoS attacks. There are rare situations where we might 2009 * get a valid KoD response, though. Since KoD packets are 2010 * a special case that complicate the checks we do next, we 2011 * handle the basic KoD checks here. 2012 * 2013 * Note that we expect the incoming KoD packet to have its 2014 * (nonzero) org, rec, and xmt timestamps set to the xmt timestamp 2015 * that we have previously sent out. Watch interleave mode. 2016 */ 2017 } else if (kissCode != NOKISS) { 2018 DEBUG_INSIST(!L_ISZERO(&p_xmt)); 2019 if ( L_ISZERO(&p_org) /* We checked p_xmt above */ 2020 || L_ISZERO(&p_rec)) { 2021 peer->bogusorg++; 2022 msyslog(LOG_INFO, 2023 "receive: KoD packet from %s has a zero org or rec timestamp. Ignoring.", 2024 ntoa(&peer->srcadr)); 2025 return; 2026 } 2027 2028 if ( !L_ISEQU(&p_xmt, &p_org) 2029 || !L_ISEQU(&p_xmt, &p_rec)) { 2030 peer->bogusorg++; 2031 msyslog(LOG_INFO, 2032 "receive: KoD packet from %s has inconsistent xmt/org/rec timestamps. Ignoring.", 2033 ntoa(&peer->srcadr)); 2034 return; 2035 } 2036 2037 /* Be conservative */ 2038 if (peer->flip == 0 && !L_ISEQU(&p_org, &peer->aorg)) { 2039 peer->bogusorg++; 2040 msyslog(LOG_INFO, 2041 "receive: flip 0 KoD origin timestamp 0x%x.%08x from %s does not match 0x%x.%08x - ignoring.", 2042 p_org.l_ui, p_org.l_uf, 2043 ntoa(&peer->srcadr), 2044 peer->aorg.l_ui, peer->aorg.l_uf); 2045 return; 2046 } else if (peer->flip == 1 && !L_ISEQU(&p_org, &peer->borg)) { 2047 peer->bogusorg++; 2048 msyslog(LOG_INFO, 2049 "receive: flip 1 KoD origin timestamp 0x%x.%08x from %s does not match interleave 0x%x.%08x - ignoring.", 2050 p_org.l_ui, p_org.l_uf, 2051 ntoa(&peer->srcadr), 2052 peer->borg.l_ui, peer->borg.l_uf); 2053 return; 2054 } 2055 2056 /* 2057 * Basic mode checks: 2058 * 2059 * If there is no origin timestamp, it's either an initial 2060 * packet or we've already received a response to our query. 2061 * Of course, should 'aorg' be all-zero because this really 2062 * was the original transmit timestamp, we'll ignore this 2063 * reply. There is a window of one nanosecond once every 2064 * 136 years' time where this is possible. We currently 2065 * ignore this situation, as a completely zero timestamp 2066 * is (quietly?) disallowed. 2067 * 2068 * Otherwise, check for bogus packet in basic mode. 2069 * If it is bogus, switch to interleaved mode and 2070 * resynchronize, but only after confirming the packet is 2071 * not bogus in symmetric interleaved mode. 2072 * 2073 * This could also mean somebody is forging packets claiming 2074 * to be from us, attempting to cause our server to KoD us. 2075 * 2076 * We have earlier asserted that hisstratum cannot be 0. 2077 * If hisstratum is STRATUM_UNSPEC, it means he's not sync'd. 2078 */ 2079 2080 /* XXX: FLAG_LOOPNONCE */ 2081 DEBUG_INSIST(0 == (FLAG_LOOPNONCE & peer->flags)); 2082 2083 if (RATEKISS == kissCode) { 2084 msyslog(LOG_INFO, "RATE KoD from %s poll %u", 2085 ntoa(&peer->srcadr), 1u << pkt->ppoll); 2086 } else { 2087 msyslog(LOG_INFO, "KoD %s from %s", 2088 refid_str(pkt->refid, -1), 2089 ntoa(&peer->srcadr)); 2090 } 2091 } else if (peer->flip == 0) { 2092 if (0) { 2093 } else if (L_ISZERO(&p_org)) { 2094 const char *action; 2095 2096 #ifdef BUG3361 2097 msyslog(LOG_INFO, 2098 "receive: BUG 3361: Clearing peer->aorg "); 2099 L_CLR(&peer->aorg); 2100 /* Clear peer->nonce, too? */ 2101 #endif 2102 /**/ 2103 switch (hismode) { 2104 /* We allow 0org for: */ 2105 case UCHAR_MAX: 2106 action = "Allow"; 2107 break; 2108 /* We disallow 0org for: */ 2109 case MODE_UNSPEC: 2110 case MODE_ACTIVE: 2111 case MODE_PASSIVE: 2112 case MODE_CLIENT: 2113 case MODE_SERVER: 2114 case MODE_BROADCAST: 2115 action = "Drop"; 2116 peer->bogusorg++; 2117 peer->flash |= TEST2; /* bogus */ 2118 break; 2119 default: 2120 action = ""; /* for cranky compilers / MSVC */ 2121 INSIST(!"receive(): impossible hismode"); 2122 break; 2123 } 2124 /**/ 2125 msyslog(LOG_INFO, 2126 "receive: %s 0 origin timestamp from %s@%s xmt 0x%x.%08x", 2127 action, hm_str, ntoa(&peer->srcadr), 2128 ntohl(pkt->xmt.l_ui), ntohl(pkt->xmt.l_uf)); 2129 } else if ( L_ISZERO(&peer->aorg) && MODE_CLIENT != hismode 2130 && !memcmp("STEP", &peer->refid, 4)) { 2131 /* response came in just after we stepped clock, normal */ 2132 } else if (!L_ISEQU(&p_org, &peer->aorg)) { 2133 /* are there cases here where we should bail? */ 2134 /* Should we set TEST2 if we decide to try xleave? */ 2135 peer->bogusorg++; 2136 peer->flash |= TEST2; /* bogus */ 2137 msyslog(LOG_INFO, 2138 "duplicate or replay: org 0x%x.%08x does not match 0x%x.%08x from %s@%s", 2139 ntohl(pkt->org.l_ui), ntohl(pkt->org.l_uf), 2140 peer->aorg.l_ui, peer->aorg.l_uf, 2141 hm_str, ntoa(&peer->srcadr)); 2142 if ( !L_ISZERO(&peer->dst) 2143 && L_ISEQU(&p_org, &peer->dst)) { 2144 /* Might be the start of an interleave */ 2145 if (dynamic_interleave) { 2146 peer->flip = 1; 2147 report_event(PEVNT_XLEAVE, peer, NULL); 2148 } else { 2149 msyslog(LOG_INFO, 2150 "receive: Dynamic interleave from %s@%s denied", 2151 hm_str, ntoa(&peer->srcadr)); 2152 } 2153 } 2154 } else { 2155 L_CLR(&peer->aorg); 2156 /* XXX: FLAG_LOOPNONCE */ 2157 } 2158 2159 /* 2160 * Check for valid nonzero timestamp fields. 2161 */ 2162 } else if ( L_ISZERO(&p_org) 2163 || L_ISZERO(&p_rec) 2164 || L_ISZERO(&peer->dst)) { 2165 peer->flash |= TEST3; /* unsynch */ 2166 2167 /* 2168 * Check for bogus packet in interleaved symmetric mode. This 2169 * can happen if a packet is lost, duplicated or crossed. If 2170 * found, flip and resynchronize. 2171 */ 2172 } else if ( !L_ISZERO(&peer->dst) 2173 && !L_ISEQU(&p_org, &peer->dst)) { 2174 DPRINTF(2, ("receive: drop: Bogus packet in interleaved symmetric mode\n")); 2175 peer->bogusorg++; 2176 peer->flags |= FLAG_XBOGUS; 2177 peer->flash |= TEST2; /* bogus */ 2178 #ifdef BUG3453 2179 return; /* Bogus packet, we are done */ 2180 #endif 2181 } 2182 2183 /**/ 2184 2185 /* 2186 * If this is a crypto_NAK, the server cannot authenticate a 2187 * client packet. The server might have just changed keys. Clear 2188 * the association and restart the protocol. 2189 */ 2190 if (crypto_nak_test == VALIDNAK) { 2191 report_event(PEVNT_AUTH, peer, "crypto_NAK"); 2192 peer->flash |= TEST5; /* bad auth */ 2193 peer->badauth++; 2194 if (peer->flags & FLAG_PREEMPT) { 2195 if (unpeer_crypto_nak_early) { 2196 unpeer(peer); 2197 } 2198 DPRINTF(2, ("receive: drop: PREEMPT crypto_NAK\n")); 2199 return; 2200 } 2201 #ifdef AUTOKEY 2202 if (peer->crypto) { 2203 peer_clear(peer, "AUTH"); 2204 } 2205 #endif /* AUTOKEY */ 2206 DPRINTF(2, ("receive: drop: crypto_NAK\n")); 2207 return; 2208 2209 /* 2210 * If the digest fails or it's missing for authenticated 2211 * associations, the client cannot authenticate a server 2212 * reply to a client packet previously sent. The loopback check 2213 * is designed to avoid a bait-and-switch attack, which was 2214 * possible in past versions. If symmetric modes, return a 2215 * crypto-NAK. The peer should restart the protocol. 2216 */ 2217 } else if (!AUTH(peer->keyid || has_mac || 2218 (restrict_mask & RES_DONTTRUST), is_authentic)) { 2219 2220 if (peer->flash & PKT_TEST_MASK) { 2221 msyslog(LOG_INFO, 2222 "receive: Bad auth in packet with bad timestamps from %s denied - spoof?", 2223 ntoa(&peer->srcadr)); 2224 return; 2225 } 2226 2227 report_event(PEVNT_AUTH, peer, "digest"); 2228 peer->flash |= TEST5; /* bad auth */ 2229 peer->badauth++; 2230 if ( has_mac 2231 && ( hismode == MODE_ACTIVE 2232 || hismode == MODE_PASSIVE)) 2233 fast_xmit(rbufp, MODE_ACTIVE, 0, restrict_mask); 2234 if (peer->flags & FLAG_PREEMPT) { 2235 if (unpeer_digest_early) { 2236 unpeer(peer); 2237 } 2238 } 2239 #ifdef AUTOKEY 2240 else if (peer_clear_digest_early && peer->crypto) { 2241 peer_clear(peer, "AUTH"); 2242 } 2243 #endif /* AUTOKEY */ 2244 DPRINTF(2, ("receive: drop: Bad or missing AUTH\n")); 2245 return; 2246 } 2247 2248 /* 2249 * For broadcast packets: 2250 * 2251 * HMS: This next line never made much sense to me, even 2252 * when it was up higher: 2253 * If an initial volley, bail out now and let the 2254 * client do its stuff. 2255 * 2256 * If the packet has not failed authentication, then 2257 * - if the origin timestamp is nonzero this is an 2258 * interleaved broadcast, so restart the protocol. 2259 * - else, this is not an interleaved broadcast packet. 2260 */ 2261 if (hismode == MODE_BROADCAST) { 2262 if ( is_authentic == AUTH_OK 2263 || is_authentic == AUTH_NONE) { 2264 if (!L_ISZERO(&p_org)) { 2265 if (!(peer->flags & FLAG_XB)) { 2266 msyslog(LOG_INFO, 2267 "receive: Broadcast server at %s is in interleave mode", 2268 ntoa(&peer->srcadr)); 2269 peer->flags |= FLAG_XB; 2270 peer->aorg = p_xmt; 2271 peer->borg = rbufp->recv_time; 2272 report_event(PEVNT_XLEAVE, peer, NULL); 2273 return; 2274 } 2275 } else if (peer->flags & FLAG_XB) { 2276 msyslog(LOG_INFO, 2277 "receive: Broadcast server at %s is no longer in interleave mode", 2278 ntoa(&peer->srcadr)); 2279 peer->flags &= ~FLAG_XB; 2280 } 2281 } else { 2282 msyslog(LOG_INFO, 2283 "receive: Bad broadcast auth (%d) from %s", 2284 is_authentic, ntoa(&peer->srcadr)); 2285 } 2286 2287 /* 2288 * Now that we know the packet is correctly authenticated, 2289 * update peer->bxmt. 2290 */ 2291 peer->bxmt = p_xmt; 2292 } 2293 2294 2295 /* 2296 ** Update the state variables. 2297 */ 2298 if (peer->flip == 0) { 2299 if (hismode != MODE_BROADCAST) 2300 peer->rec = p_xmt; 2301 peer->dst = rbufp->recv_time; 2302 } 2303 peer->xmt = p_xmt; 2304 2305 /* 2306 * Set the peer ppoll to the maximum of the packet ppoll and the 2307 * peer minpoll. If a kiss-o'-death, set the peer minpoll to 2308 * this maximum and advance the headway to give the sender some 2309 * headroom. Very intricate. 2310 */ 2311 peer->ppoll = max(peer->minpoll, pkt->ppoll); 2312 2313 /* 2314 * Check for any kiss codes. Note this is only used when a server 2315 * responds to a client request. 2316 */ 2317 if (kissCode == RATEKISS) { 2318 if ( pkt->ppoll < NTP_MINPOLL 2319 || pkt->ppoll > NTP_MAXPOLL) { 2320 DPRINTF(2, ("Ignoring ppoll %d RATE KoD from %s\n", 2321 pkt->ppoll, stoa(&rbufp->recv_srcadr))); 2322 sys_badlength++; 2323 return; /* invalid packet poll */ 2324 } 2325 peer->selbroken++; /* Increment the KoD count */ 2326 report_event(PEVNT_RATE, peer, NULL); 2327 peer->minpoll = peer->ppoll; 2328 peer->burst = peer->retry = 0; 2329 peer->throttle = (NTP_SHIFT + 1) * (1 << peer->minpoll); 2330 poll_update(peer, pkt->ppoll, 0); 2331 return; /* kiss-o'-death */ 2332 } else if (kissCode != NOKISS) { 2333 peer->selbroken++; /* Increment the KoD count */ 2334 return; /* Drop any other kiss code packets */ 2335 } 2336 2337 2338 /* 2339 * XXX 2340 */ 2341 2342 2343 /* 2344 * If: 2345 * - this is a *cast (uni-, broad-, or m-) server packet 2346 * - and it's symmetric-key authenticated 2347 * then see if the sender's IP is trusted for this keyid. 2348 * If it is, great - nothing special to do here. 2349 * Otherwise, we should report and bail. 2350 * 2351 * Autokey-authenticated packets are accepted. 2352 */ 2353 2354 switch (hismode) { 2355 case MODE_SERVER: /* server mode */ 2356 case MODE_BROADCAST: /* broadcast mode */ 2357 case MODE_ACTIVE: /* symmetric active mode */ 2358 case MODE_PASSIVE: /* symmetric passive mode */ 2359 if ( is_authentic == AUTH_OK 2360 && skeyid 2361 && skeyid <= NTP_MAXKEY 2362 && !authistrustedip(skeyid, &peer->srcadr)) { 2363 report_event(PEVNT_AUTH, peer, "authIP"); 2364 peer->badauth++; 2365 return; 2366 } 2367 break; 2368 2369 case MODE_CLIENT: /* client mode */ 2370 #if 0 /* At this point, MODE_CONTROL is overloaded by MODE_BCLIENT */ 2371 case MODE_CONTROL: /* control mode */ 2372 #endif 2373 case MODE_PRIVATE: /* private mode */ 2374 case MODE_BCLIENT: /* broadcast client mode */ 2375 break; 2376 2377 case MODE_UNSPEC: /* unspecified (old version) */ 2378 default: 2379 msyslog(LOG_INFO, 2380 "receive: Unexpected mode (%d) in packet from %s", 2381 hismode, ntoa(&peer->srcadr)); 2382 break; 2383 } 2384 2385 2386 /* 2387 * That was hard and I am sweaty, but the packet is squeaky 2388 * clean. Get on with real work. 2389 */ 2390 peer->timereceived = current_time; 2391 peer->timelastrec = current_time; 2392 if (is_authentic == AUTH_OK) 2393 peer->flags |= FLAG_AUTHENTIC; 2394 else 2395 peer->flags &= ~FLAG_AUTHENTIC; 2396 2397 #ifdef AUTOKEY 2398 /* 2399 * More autokey dance. The rules of the cha-cha are as follows: 2400 * 2401 * 1. If there is no key or the key is not auto, do nothing. 2402 * 2403 * 2. If this packet is in response to the one just previously 2404 * sent or from a broadcast server, do the extension fields. 2405 * Otherwise, assume bogosity and bail out. 2406 * 2407 * 3. If an extension field contains a verified signature, it is 2408 * self-authenticated and we sit the dance. 2409 * 2410 * 4. If this is a server reply, check only to see that the 2411 * transmitted key ID matches the received key ID. 2412 * 2413 * 5. Check to see that one or more hashes of the current key ID 2414 * matches the previous key ID or ultimate original key ID 2415 * obtained from the broadcaster or symmetric peer. If no 2416 * match, sit the dance and call for new autokey values. 2417 * 2418 * In case of crypto error, fire the orchestra, stop dancing and 2419 * restart the protocol. 2420 */ 2421 if (peer->flags & FLAG_SKEY) { 2422 /* 2423 * Decrement remaining autokey hashes. This isn't 2424 * perfect if a packet is lost, but results in no harm. 2425 */ 2426 ap = (struct autokey *)peer->recval.ptr; 2427 if (ap != NULL) { 2428 if (ap->seq > 0) 2429 ap->seq--; 2430 } 2431 peer->flash |= TEST8; 2432 rval = crypto_recv(peer, rbufp); 2433 if (rval == XEVNT_OK) { 2434 peer->unreach = 0; 2435 } else { 2436 if (rval == XEVNT_ERR) { 2437 report_event(PEVNT_RESTART, peer, 2438 "crypto error"); 2439 peer_clear(peer, "CRYP"); 2440 peer->flash |= TEST9; /* bad crypt */ 2441 if (peer->flags & FLAG_PREEMPT) { 2442 if (unpeer_crypto_early) { 2443 unpeer(peer); 2444 } 2445 } 2446 } 2447 return; 2448 } 2449 2450 /* 2451 * If server mode, verify the receive key ID matches 2452 * the transmit key ID. 2453 */ 2454 if (hismode == MODE_SERVER) { 2455 if (skeyid == peer->keyid) 2456 peer->flash &= ~TEST8; 2457 2458 /* 2459 * If an extension field is present, verify only that it 2460 * has been correctly signed. We don't need a sequence 2461 * check here, but the sequence continues. 2462 */ 2463 } else if (!(peer->flash & TEST8)) { 2464 peer->pkeyid = skeyid; 2465 2466 /* 2467 * Now the fun part. Here, skeyid is the current ID in 2468 * the packet, pkeyid is the ID in the last packet and 2469 * tkeyid is the hash of skeyid. If the autokey values 2470 * have not been received, this is an automatic error. 2471 * If so, check that the tkeyid matches pkeyid. If not, 2472 * hash tkeyid and try again. If the number of hashes 2473 * exceeds the number remaining in the sequence, declare 2474 * a successful failure and refresh the autokey values. 2475 */ 2476 } else if (ap != NULL) { 2477 int i; 2478 2479 for (i = 0; ; i++) { 2480 if ( tkeyid == peer->pkeyid 2481 || tkeyid == ap->key) { 2482 peer->flash &= ~TEST8; 2483 peer->pkeyid = skeyid; 2484 ap->seq -= i; 2485 break; 2486 } 2487 if (i > ap->seq) { 2488 peer->crypto &= 2489 ~CRYPTO_FLAG_AUTO; 2490 break; 2491 } 2492 tkeyid = session_key( 2493 &rbufp->recv_srcadr, dstadr_sin, 2494 tkeyid, pkeyid, 0); 2495 } 2496 if (peer->flash & TEST8) 2497 report_event(PEVNT_AUTH, peer, "keylist"); 2498 } 2499 if (!(peer->crypto & CRYPTO_FLAG_PROV)) /* test 9 */ 2500 peer->flash |= TEST8; /* bad autokey */ 2501 2502 /* 2503 * The maximum lifetime of the protocol is about one 2504 * week before restarting the Autokey protocol to 2505 * refresh certificates and leapseconds values. 2506 */ 2507 if (current_time > peer->refresh) { 2508 report_event(PEVNT_RESTART, peer, 2509 "crypto refresh"); 2510 peer_clear(peer, "TIME"); 2511 return; 2512 } 2513 } 2514 #endif /* AUTOKEY */ 2515 2516 /* 2517 * The dance is complete and the flash bits have been lit. Toss 2518 * the packet over the fence for processing, which may light up 2519 * more flashers. Leave if the packet is not good. 2520 */ 2521 process_packet(peer, pkt, rbufp->recv_length); 2522 /* Bug 2734: TEST3 prevents initial interleave sync */ 2523 if ((~TEST3 & peer->flash) & PKT_TEST_MASK) { 2524 return; 2525 } 2526 2527 /* [bug 3592] Update poll. Ideally this should not happen in a 2528 * receive branch, but too much is going on here... at least we 2529 * do it only if the packet was good! 2530 */ 2531 poll_update(peer, peer->hpoll, (peer->hmode == MODE_CLIENT)); 2532 2533 /* 2534 * In interleaved mode update the state variables. Also adjust the 2535 * transmit phase to avoid crossover. 2536 */ 2537 if (peer->flip != 0) { 2538 peer->rec = p_rec; 2539 peer->dst = rbufp->recv_time; 2540 if (peer->nextdate - current_time < (1U << min(peer->ppoll, 2541 peer->hpoll)) / 2) 2542 peer->nextdate++; 2543 else 2544 peer->nextdate--; 2545 } 2546 } 2547 2548 2549 /* 2550 * process_packet - Packet Procedure, a la Section 3.4.4 of RFC-1305 2551 * Or almost, at least. If we're in here we have a reasonable 2552 * expectation that we will be having a long term 2553 * relationship with this host. 2554 */ 2555 void 2556 process_packet( 2557 register struct peer *peer, 2558 register struct pkt *pkt, 2559 u_int len 2560 ) 2561 { 2562 double t34, t21; 2563 double p_offset, p_del, p_disp; 2564 l_fp p_rec, p_xmt, p_org, p_reftime, ci; 2565 u_char pmode, pleap, pversion, pstratum; 2566 #ifdef ASSYM 2567 int itemp; 2568 double etemp, ftemp, td; 2569 #endif /* ASSYM */ 2570 2571 p_del = FPTOD(NTOHS_FP(pkt->rootdelay)); 2572 p_offset = 0; 2573 p_disp = FPTOD(NTOHS_FP(pkt->rootdisp)); 2574 NTOHL_FP(&pkt->reftime, &p_reftime); 2575 NTOHL_FP(&pkt->org, &p_org); 2576 NTOHL_FP(&pkt->rec, &p_rec); 2577 NTOHL_FP(&pkt->xmt, &p_xmt); 2578 pmode = PKT_MODE(pkt->li_vn_mode); 2579 pleap = PKT_LEAP(pkt->li_vn_mode); 2580 pversion = PKT_VERSION(pkt->li_vn_mode); 2581 pstratum = PKT_TO_STRATUM(pkt->stratum); 2582 2583 /* 2584 * Verify the server is synchronized; that is, the leap bits, 2585 * stratum and root distance are valid. 2586 */ 2587 if ( pleap == LEAP_NOTINSYNC /* test 6 */ 2588 || pstratum < sys_floor || pstratum >= sys_ceiling) 2589 peer->flash |= TEST6; /* bad synch or strat */ 2590 if (p_del / 2 + p_disp >= MAXDISPERSE) /* test 7 */ 2591 peer->flash |= TEST7; /* bad header */ 2592 2593 /* 2594 * If any tests fail at this point, the packet is discarded. 2595 * Note that some flashers may have already been set in the 2596 * receive() routine. 2597 */ 2598 if (peer->flash & PKT_TEST_MASK) { 2599 peer->seldisptoolarge++; 2600 DPRINTF(1, ("packet: flash header %04x\n", 2601 peer->flash)); 2602 /* [Bug 3592] do *not* update poll on bad packets! */ 2603 return; 2604 } 2605 2606 /* 2607 * update stats, now that we really handle this packet: 2608 */ 2609 sys_processed++; 2610 peer->processed++; 2611 2612 /* 2613 * Capture the header values in the client/peer association.. 2614 */ 2615 record_raw_stats(&peer->srcadr, 2616 peer->dstadr ? &peer->dstadr->sin : NULL, 2617 &p_org, &p_rec, &p_xmt, &peer->dst, 2618 pleap, pversion, pmode, pstratum, pkt->ppoll, pkt->precision, 2619 p_del, p_disp, pkt->refid, 2620 len - MIN_V4_PKT_LEN, (u_char *)&pkt->exten); 2621 peer->leap = pleap; 2622 peer->stratum = min(pstratum, STRATUM_UNSPEC); 2623 peer->pmode = pmode; 2624 peer->precision = pkt->precision; 2625 peer->rootdelay = p_del; 2626 peer->rootdisp = p_disp; 2627 peer->refid = pkt->refid; /* network byte order */ 2628 peer->reftime = p_reftime; 2629 2630 /* 2631 * First, if either burst mode is armed, enable the burst. 2632 * Compute the headway for the next packet and delay if 2633 * necessary to avoid exceeding the threshold. 2634 */ 2635 if (peer->retry > 0) { 2636 peer->retry = 0; 2637 if (peer->reach) 2638 peer->burst = min(1 << (peer->hpoll - 2639 peer->minpoll), NTP_SHIFT) - 1; 2640 else 2641 peer->burst = NTP_IBURST - 1; 2642 if (peer->burst > 0) 2643 peer->nextdate = current_time; 2644 } 2645 2646 /* 2647 * If the peer was previously unreachable, raise a trap. In any 2648 * case, mark it reachable. 2649 */ 2650 if (!peer->reach) { 2651 report_event(PEVNT_REACH, peer, NULL); 2652 peer->timereachable = current_time; 2653 } 2654 peer->reach |= 1; 2655 2656 /* 2657 * For a client/server association, calculate the clock offset, 2658 * roundtrip delay and dispersion. The equations are reordered 2659 * from the spec for more efficient use of temporaries. For a 2660 * broadcast association, offset the last measurement by the 2661 * computed delay during the client/server volley. Note the 2662 * computation of dispersion includes the system precision plus 2663 * that due to the frequency error since the origin time. 2664 * 2665 * It is very important to respect the hazards of overflow. The 2666 * only permitted operation on raw timestamps is subtraction, 2667 * where the result is a signed quantity spanning from 68 years 2668 * in the past to 68 years in the future. To avoid loss of 2669 * precision, these calculations are done using 64-bit integer 2670 * arithmetic. However, the offset and delay calculations are 2671 * sums and differences of these first-order differences, which 2672 * if done using 64-bit integer arithmetic, would be valid over 2673 * only half that span. Since the typical first-order 2674 * differences are usually very small, they are converted to 64- 2675 * bit doubles and all remaining calculations done in floating- 2676 * double arithmetic. This preserves the accuracy while 2677 * retaining the 68-year span. 2678 * 2679 * There are three interleaving schemes, basic, interleaved 2680 * symmetric and interleaved broadcast. The timestamps are 2681 * idioscyncratically different. See the onwire briefing/white 2682 * paper at www.eecis.udel.edu/~mills for details. 2683 * 2684 * Interleaved symmetric mode 2685 * t1 = peer->aorg/borg, t2 = peer->rec, t3 = p_xmt, 2686 * t4 = peer->dst 2687 */ 2688 if (peer->flip != 0) { 2689 ci = p_xmt; /* t3 - t4 */ 2690 L_SUB(&ci, &peer->dst); 2691 LFPTOD(&ci, t34); 2692 ci = p_rec; /* t2 - t1 */ 2693 if (peer->flip > 0) 2694 L_SUB(&ci, &peer->borg); 2695 else 2696 L_SUB(&ci, &peer->aorg); 2697 LFPTOD(&ci, t21); 2698 p_del = t21 - t34; 2699 p_offset = (t21 + t34) / 2.; 2700 if (p_del < 0 || p_del > 1.) { 2701 mprintf_event(PEVNT_XERR, peer, 2702 "t21 %.9f t34 %.9f", t21, t34); 2703 return; 2704 } 2705 2706 /* 2707 * Broadcast modes 2708 */ 2709 } else if (peer->pmode == MODE_BROADCAST) { 2710 2711 /* 2712 * Interleaved broadcast mode. Use interleaved timestamps. 2713 * t1 = peer->borg, t2 = p_org, t3 = p_org, t4 = aorg 2714 */ 2715 if (peer->flags & FLAG_XB) { 2716 ci = p_org; /* delay */ 2717 L_SUB(&ci, &peer->aorg); 2718 LFPTOD(&ci, t34); 2719 ci = p_org; /* t2 - t1 */ 2720 L_SUB(&ci, &peer->borg); 2721 LFPTOD(&ci, t21); 2722 peer->aorg = p_xmt; 2723 peer->borg = peer->dst; 2724 if (t34 < 0 || t34 > 1.) { 2725 /* drop all if in the initial volley */ 2726 if (FLAG_BC_VOL & peer->flags) 2727 goto bcc_init_volley_fail; 2728 mprintf_event(PEVNT_XERR, peer, 2729 "offset %.9f delay %.9f", 2730 t21, t34); 2731 return; 2732 } 2733 p_offset = t21; 2734 peer->xleave = t34; 2735 2736 /* 2737 * Basic broadcast - use direct timestamps. 2738 * t3 = p_xmt, t4 = peer->dst 2739 */ 2740 } else { 2741 ci = p_xmt; /* t3 - t4 */ 2742 L_SUB(&ci, &peer->dst); 2743 LFPTOD(&ci, t34); 2744 p_offset = t34; 2745 } 2746 2747 /* 2748 * When calibration is complete and the clock is 2749 * synchronized, the bias is calculated as the difference 2750 * between the unicast timestamp and the broadcast 2751 * timestamp. This works for both basic and interleaved 2752 * modes. 2753 * [Bug 3031] Don't keep this peer when the delay 2754 * calculation gives reason to suspect clock steps. 2755 * This is assumed for delays > 50ms. 2756 */ 2757 if (FLAG_BC_VOL & peer->flags) { 2758 peer->flags &= ~FLAG_BC_VOL; 2759 peer->delay = fabs(peer->offset - p_offset) * 2; 2760 DPRINTF(2, ("broadcast volley: initial delay=%.6f\n", 2761 peer->delay)); 2762 if (peer->delay > fabs(sys_bdelay)) { 2763 bcc_init_volley_fail: 2764 DPRINTF(2, ("%s", "broadcast volley: initial delay exceeds limit\n")); 2765 unpeer(peer); 2766 return; 2767 } 2768 } 2769 peer->nextdate = current_time + (1u << peer->ppoll) - 2u; 2770 p_del = peer->delay; 2771 p_offset += p_del / 2; 2772 2773 2774 /* 2775 * Basic mode, otherwise known as the old fashioned way. 2776 * 2777 * t1 = p_org, t2 = p_rec, t3 = p_xmt, t4 = peer->dst 2778 */ 2779 } else { 2780 ci = p_xmt; /* t3 - t4 */ 2781 L_SUB(&ci, &peer->dst); 2782 LFPTOD(&ci, t34); 2783 ci = p_rec; /* t2 - t1 */ 2784 L_SUB(&ci, &p_org); 2785 LFPTOD(&ci, t21); 2786 p_del = fabs(t21 - t34); 2787 p_offset = (t21 + t34) / 2.; 2788 } 2789 p_del = max(p_del, LOGTOD(sys_precision)); 2790 p_disp = LOGTOD(sys_precision) + LOGTOD(peer->precision) + 2791 clock_phi * p_del; 2792 2793 #if ASSYM 2794 /* 2795 * This code calculates the outbound and inbound data rates by 2796 * measuring the differences between timestamps at different 2797 * packet lengths. This is helpful in cases of large asymmetric 2798 * delays commonly experienced on deep space communication 2799 * links. 2800 */ 2801 if (peer->t21_last > 0 && peer->t34_bytes > 0) { 2802 itemp = peer->t21_bytes - peer->t21_last; 2803 if (itemp > 25) { 2804 etemp = t21 - peer->t21; 2805 if (fabs(etemp) > 1e-6) { 2806 ftemp = itemp / etemp; 2807 if (ftemp > 1000.) 2808 peer->r21 = ftemp; 2809 } 2810 } 2811 itemp = len - peer->t34_bytes; 2812 if (itemp > 25) { 2813 etemp = -t34 - peer->t34; 2814 if (fabs(etemp) > 1e-6) { 2815 ftemp = itemp / etemp; 2816 if (ftemp > 1000.) 2817 peer->r34 = ftemp; 2818 } 2819 } 2820 } 2821 2822 /* 2823 * The following section compensates for different data rates on 2824 * the outbound (d21) and inbound (t34) directions. To do this, 2825 * it finds t such that r21 * t - r34 * (d - t) = 0, where d is 2826 * the roundtrip delay. Then it calculates the correction as a 2827 * fraction of d. 2828 */ 2829 peer->t21 = t21; 2830 peer->t21_last = peer->t21_bytes; 2831 peer->t34 = -t34; 2832 peer->t34_bytes = len; 2833 DPRINTF(2, ("packet: t21 %.9lf %d t34 %.9lf %d\n", peer->t21, 2834 peer->t21_bytes, peer->t34, peer->t34_bytes)); 2835 if (peer->r21 > 0 && peer->r34 > 0 && p_del > 0) { 2836 if (peer->pmode != MODE_BROADCAST) 2837 td = (peer->r34 / (peer->r21 + peer->r34) - 2838 .5) * p_del; 2839 else 2840 td = 0; 2841 2842 /* 2843 * Unfortunately, in many cases the errors are 2844 * unacceptable, so for the present the rates are not 2845 * used. In future, we might find conditions where the 2846 * calculations are useful, so this should be considered 2847 * a work in progress. 2848 */ 2849 t21 -= td; 2850 t34 -= td; 2851 DPRINTF(2, ("packet: del %.6lf r21 %.1lf r34 %.1lf %.6lf\n", 2852 p_del, peer->r21 / 1e3, peer->r34 / 1e3, 2853 td)); 2854 } 2855 #endif /* ASSYM */ 2856 2857 /* 2858 * That was awesome. Now hand off to the clock filter. 2859 */ 2860 clock_filter(peer, p_offset + peer->bias, p_del, p_disp); 2861 2862 /* 2863 * If we are in broadcast calibrate mode, return to broadcast 2864 * client mode when the client is fit and the autokey dance is 2865 * complete. 2866 */ 2867 if ( (FLAG_BC_VOL & peer->flags) 2868 && MODE_CLIENT == peer->hmode 2869 && !(TEST11 & peer_unfit(peer))) { /* distance exceeded */ 2870 #ifdef AUTOKEY 2871 if (peer->flags & FLAG_SKEY) { 2872 if (!(~peer->crypto & CRYPTO_FLAG_ALL)) 2873 peer->hmode = MODE_BCLIENT; 2874 } else { 2875 peer->hmode = MODE_BCLIENT; 2876 } 2877 #else /* !AUTOKEY follows */ 2878 peer->hmode = MODE_BCLIENT; 2879 #endif /* !AUTOKEY */ 2880 } 2881 } 2882 2883 2884 /* 2885 * clock_update - Called at system process update intervals. 2886 */ 2887 static void 2888 clock_update( 2889 struct peer *peer /* peer structure pointer */ 2890 ) 2891 { 2892 double dtemp; 2893 l_fp now; 2894 #ifdef HAVE_LIBSCF_H 2895 char *fmri; 2896 #endif /* HAVE_LIBSCF_H */ 2897 2898 /* 2899 * Update the system state variables. We do this very carefully, 2900 * as the poll interval might need to be clamped differently. 2901 */ 2902 sys_peer = peer; 2903 sys_epoch = peer->epoch; 2904 if (sys_poll < peer->minpoll) 2905 sys_poll = peer->minpoll; 2906 if (sys_poll > peer->maxpoll) 2907 sys_poll = peer->maxpoll; 2908 poll_update(peer, sys_poll, 0); 2909 sys_stratum = min(peer->stratum + 1, STRATUM_UNSPEC); 2910 if ( peer->stratum == STRATUM_REFCLOCK 2911 || peer->stratum == STRATUM_UNSPEC) 2912 sys_refid = peer->refid; 2913 else 2914 sys_refid = addr2refid(&peer->srcadr); 2915 /* 2916 * Root Dispersion (E) is defined (in RFC 5905) as: 2917 * 2918 * E = p.epsilon_r + p.epsilon + p.psi + PHI*(s.t - p.t) + |THETA| 2919 * 2920 * where: 2921 * p.epsilon_r is the PollProc's root dispersion 2922 * p.epsilon is the PollProc's dispersion 2923 * p.psi is the PollProc's jitter 2924 * THETA is the combined offset 2925 * 2926 * NB: Think Hard about where these numbers come from and 2927 * what they mean. When did peer->update happen? Has anything 2928 * interesting happened since then? What values are the most 2929 * defensible? Why? 2930 * 2931 * DLM thinks this equation is probably the best of all worse choices. 2932 */ 2933 dtemp = peer->rootdisp 2934 + peer->disp 2935 + sys_jitter 2936 + clock_phi * (current_time - peer->update) 2937 + fabs(sys_offset); 2938 2939 p2_rootdisp = prev_rootdisp; 2940 prev_rootdisp = sys_rootdisp; 2941 if (dtemp > sys_mindisp) 2942 sys_rootdisp = dtemp; 2943 else 2944 sys_rootdisp = sys_mindisp; 2945 2946 sys_rootdelay = peer->delay + peer->rootdelay; 2947 2948 p2_reftime = prev_reftime; 2949 p2_time = prev_time; 2950 2951 prev_reftime = sys_reftime; 2952 prev_time = current_time + 64 + (rand() & 0x3f); /* 64-127 s */ 2953 2954 sys_reftime = peer->dst; 2955 2956 DPRINTF(1, ("clock_update: at %lu sample %lu associd %d\n", 2957 current_time, peer->epoch, peer->associd)); 2958 2959 /* 2960 * Comes now the moment of truth. Crank the clock discipline and 2961 * see what comes out. 2962 */ 2963 switch (local_clock(peer, sys_offset)) { 2964 2965 /* 2966 * Clock exceeds panic threshold. Life as we know it ends. 2967 */ 2968 case -1: 2969 msyslog(LOG_ERR, "Clock offset exceeds panic threshold."); 2970 #ifdef HAVE_LIBSCF_H 2971 /* 2972 * For Solaris enter the maintenance mode. 2973 */ 2974 if ((fmri = getenv("SMF_FMRI")) != NULL) { 2975 if (smf_maintain_instance(fmri, 0) < 0) { 2976 msyslog(LOG_ERR, "smf_maintain_instance: %s", 2977 scf_strerror(scf_error())); 2978 exit(1); 2979 } 2980 /* 2981 * Sleep until SMF kills us. 2982 */ 2983 msyslog(LOG_ERR, "%s placed into maintenance. " 2984 "Set system clock by hand before clearing.", 2985 fmri); 2986 for (;;) 2987 pause(); 2988 } 2989 #endif /* HAVE_LIBSCF_H */ 2990 msyslog(LOG_ERR, "Set system clock by hand."); 2991 exit (-1); 2992 /* not reached */ 2993 2994 /* 2995 * Clock was stepped. Flush all time values of all peers. 2996 */ 2997 case 2: 2998 clear_all(); 2999 set_sys_leap(LEAP_NOTINSYNC); 3000 sys_stratum = STRATUM_UNSPEC; 3001 memcpy(&sys_refid, "STEP", 4); 3002 sys_rootdelay = 0; 3003 p2_rootdisp = 0; 3004 prev_rootdisp = 0; 3005 sys_rootdisp = 0; 3006 L_CLR(&p2_reftime); /* Should we clear p2_reftime? */ 3007 L_CLR(&prev_reftime); /* Should we clear prev_reftime? */ 3008 L_CLR(&sys_reftime); 3009 sys_jitter = LOGTOD(sys_precision); 3010 leapsec_reset_frame(); 3011 break; 3012 3013 /* 3014 * Clock was slewed. Handle the leapsecond stuff. 3015 */ 3016 case 1: 3017 3018 /* 3019 * If this is the first time the clock is set, reset the 3020 * leap bits. If crypto, the timer will goose the setup 3021 * process. 3022 */ 3023 if (sys_leap == LEAP_NOTINSYNC) { 3024 set_sys_leap(LEAP_NOWARNING); 3025 #ifdef AUTOKEY 3026 if (crypto_flags) 3027 crypto_update(); 3028 #endif /* AUTOKEY */ 3029 3030 } 3031 3032 /* 3033 * If there is no leap second pending and the number of 3034 * survivor leap bits is greater than half the number of 3035 * survivors, try to schedule a leap for the end of the 3036 * current month. (This only works if no leap second for 3037 * that range is in the table, so doing this more than 3038 * once is mostly harmless.) 3039 */ 3040 if (leapsec == LSPROX_NOWARN) { 3041 if ( leap_vote_ins > leap_vote_del 3042 && leap_vote_ins > sys_survivors / 2) { 3043 get_systime(&now); 3044 leapsec_add_dyn(TRUE, now.l_ui, NULL); 3045 } 3046 if ( leap_vote_del > leap_vote_ins 3047 && leap_vote_del > sys_survivors / 2) { 3048 get_systime(&now); 3049 leapsec_add_dyn(FALSE, now.l_ui, NULL); 3050 } 3051 } 3052 break; 3053 3054 /* 3055 * Popcorn spike or step threshold exceeded. Pretend it never 3056 * happened. 3057 */ 3058 default: 3059 break; 3060 } 3061 } 3062 3063 3064 /* 3065 * poll_update - update peer poll interval 3066 */ 3067 void 3068 poll_update( 3069 struct peer *peer, /* peer structure pointer */ 3070 u_char mpoll, 3071 u_char skewpoll 3072 ) 3073 { 3074 u_long next, utemp, limit; 3075 u_char hpoll; 3076 3077 /* 3078 * This routine figures out when the next poll should be sent. 3079 * That turns out to be wickedly complicated. One problem is 3080 * that sometimes the time for the next poll is in the past when 3081 * the poll interval is reduced. We watch out for races here 3082 * between the receive process and the poll process. 3083 * 3084 * Clamp the poll interval between minpoll and maxpoll. 3085 */ 3086 hpoll = max(min(peer->maxpoll, mpoll), peer->minpoll); 3087 3088 #ifdef AUTOKEY 3089 /* 3090 * If during the crypto protocol the poll interval has changed, 3091 * the lifetimes in the key list are probably bogus. Purge the 3092 * the key list and regenerate it later. 3093 */ 3094 if ((peer->flags & FLAG_SKEY) && hpoll != peer->hpoll) 3095 key_expire(peer); 3096 #endif /* AUTOKEY */ 3097 peer->hpoll = hpoll; 3098 3099 /* 3100 * There are three variables important for poll scheduling, the 3101 * current time (current_time), next scheduled time (nextdate) 3102 * and the earliest time (utemp). The earliest time is 2 s 3103 * seconds, but could be more due to rate management. When 3104 * sending in a burst, use the earliest time. When not in a 3105 * burst but with a reply pending, send at the earliest time 3106 * unless the next scheduled time has not advanced. This can 3107 * only happen if multiple replies are pending in the same 3108 * response interval. Otherwise, send at the later of the next 3109 * scheduled time and the earliest time. 3110 * 3111 * Now we figure out if there is an override. If a burst is in 3112 * progress and we get called from the receive process, just 3113 * slink away. If called from the poll process, delay 1 s for a 3114 * reference clock, otherwise 2 s. 3115 */ 3116 utemp = current_time + max(peer->throttle - (NTP_SHIFT - 1) * 3117 (1 << peer->minpoll), ntp_minpkt); 3118 3119 /*[Bug 3592] avoid unlimited postpone of next poll */ 3120 limit = (2u << hpoll); 3121 if (limit > 64) 3122 limit -= (limit >> 2); 3123 limit += peer->outdate; 3124 if (limit < current_time) 3125 limit = current_time; 3126 3127 if (peer->burst > 0) { 3128 if (peer->nextdate > current_time) 3129 return; 3130 #ifdef REFCLOCK 3131 else if (peer->flags & FLAG_REFCLOCK) 3132 peer->nextdate = current_time + RESP_DELAY; 3133 #endif /* REFCLOCK */ 3134 else 3135 peer->nextdate = utemp; 3136 3137 #ifdef AUTOKEY 3138 /* 3139 * If a burst is not in progress and a crypto response message 3140 * is pending, delay 2 s, but only if this is a new interval. 3141 */ 3142 } else if (peer->cmmd != NULL) { 3143 if (peer->nextdate > current_time) { 3144 if (peer->nextdate + ntp_minpkt != utemp) 3145 peer->nextdate = utemp; 3146 } else { 3147 peer->nextdate = utemp; 3148 } 3149 #endif /* AUTOKEY */ 3150 3151 /* 3152 * The ordinary case. If a retry, use minpoll; if unreachable, 3153 * use host poll; otherwise, use the minimum of host and peer 3154 * polls; In other words, oversampling is okay but 3155 * understampling is evil. Use the maximum of this value and the 3156 * headway. If the average headway is greater than the headway 3157 * threshold, increase the headway by the minimum interval. 3158 */ 3159 } else { 3160 if (peer->retry > 0) 3161 hpoll = peer->minpoll; 3162 else 3163 hpoll = min(peer->ppoll, peer->hpoll); 3164 #ifdef REFCLOCK 3165 if (peer->flags & FLAG_REFCLOCK) 3166 next = 1 << hpoll; 3167 else 3168 #endif /* REFCLOCK */ 3169 next = ((0x1000UL | (ntp_random() & 0x0ff)) << 3170 hpoll) >> 12; 3171 next += peer->outdate; 3172 /* XXX: bug3596: Deal with poll skew list? */ 3173 if (skewpoll) { 3174 psl_item psi; 3175 3176 if (0 == get_pollskew(hpoll, &psi)) { 3177 int sub = psi.sub; 3178 int qty = psi.qty; 3179 int msk = psi.msk; 3180 int val; 3181 3182 if ( 0 != sub 3183 || 0 != qty) { 3184 do { 3185 val = ntp_random() & msk; 3186 } while (val > qty); 3187 3188 next -= sub; 3189 next += val; 3190 } 3191 } else { 3192 /* get_pollskew() already logged this */ 3193 } 3194 } 3195 if (next > utemp) 3196 peer->nextdate = next; 3197 else 3198 peer->nextdate = utemp; 3199 if (peer->throttle > (1 << peer->minpoll)) 3200 peer->nextdate += ntp_minpkt; 3201 } 3202 3203 /*[Bug 3592] avoid unlimited postpone of next poll */ 3204 if (peer->nextdate > limit) { 3205 DPRINTF(1, ("poll_update: clamp reached; limit %lu next %lu\n", 3206 limit, peer->nextdate)); 3207 peer->nextdate = limit; 3208 } 3209 DPRINTF(2, ("poll_update: at %lu %s poll %d burst %d retry %d head %d early %lu next %lu\n", 3210 current_time, ntoa(&peer->srcadr), peer->hpoll, 3211 peer->burst, peer->retry, peer->throttle, 3212 utemp - current_time, peer->nextdate - 3213 current_time)); 3214 } 3215 3216 3217 /* 3218 * peer_clear - clear peer filter registers. See Section 3.4.8 of the 3219 * spec. 3220 */ 3221 void 3222 peer_clear( 3223 struct peer *peer, /* peer structure */ 3224 const char *ident /* tally lights */ 3225 ) 3226 { 3227 static u_long earliest; 3228 u_char u; 3229 l_fp bxmt = peer->bxmt; /* bcast clients retain this! */ 3230 3231 #ifdef AUTOKEY 3232 /* 3233 * If cryptographic credentials have been acquired, toss them to 3234 * Valhalla. Note that autokeys are ephemeral, in that they are 3235 * tossed immediately upon use. Therefore, the keylist can be 3236 * purged anytime without needing to preserve random keys. Note 3237 * that, if the peer is purged, the cryptographic variables are 3238 * purged, too. This makes it much harder to sneak in some 3239 * unauthenticated data in the clock filter. 3240 */ 3241 key_expire(peer); 3242 if (peer->iffval != NULL) 3243 BN_free(peer->iffval); 3244 value_free(&peer->cookval); 3245 value_free(&peer->recval); 3246 value_free(&peer->encrypt); 3247 value_free(&peer->sndval); 3248 if (peer->cmmd != NULL) 3249 free(peer->cmmd); 3250 if (peer->subject != NULL) 3251 free(peer->subject); 3252 if (peer->issuer != NULL) 3253 free(peer->issuer); 3254 #endif /* AUTOKEY */ 3255 3256 /* 3257 * Clear all values, including the optional crypto values above. 3258 */ 3259 memset(CLEAR_TO_ZERO(peer), 0, LEN_CLEAR_TO_ZERO(peer)); 3260 peer->ppoll = peer->maxpoll; 3261 peer->hpoll = peer->minpoll; 3262 peer->disp = MAXDISPERSE; 3263 peer->flash = peer_unfit(peer); 3264 peer->jitter = LOGTOD(sys_precision); 3265 3266 /* Don't throw away our broadcast replay protection */ 3267 if (peer->hmode == MODE_BCLIENT) 3268 peer->bxmt = bxmt; 3269 3270 /* 3271 * If interleave mode, initialize the alternate origin switch. 3272 */ 3273 if (peer->flags & FLAG_XLEAVE) 3274 peer->flip = 1; 3275 for (u = 0; u < NTP_SHIFT; u++) { 3276 peer->filter_order[u] = u; 3277 peer->filter_disp[u] = MAXDISPERSE; 3278 } 3279 #ifdef REFCLOCK 3280 if (!(peer->flags & FLAG_REFCLOCK)) { 3281 #endif 3282 peer->leap = LEAP_NOTINSYNC; 3283 peer->stratum = STRATUM_UNSPEC; 3284 memcpy(&peer->refid, ident, 4); 3285 #ifdef REFCLOCK 3286 } else { 3287 /* Clear refclock sample filter */ 3288 peer->procptr->codeproc = 0; 3289 peer->procptr->coderecv = 0; 3290 } 3291 #endif 3292 3293 /* 3294 * During initialization use the association count to spread out 3295 * the polls at one-second intervals. Unconfigured associations' 3296 * first poll is delayed by the "discard minimum" plus 1 to avoid 3297 * rate limiting. Other post-startup new or cleared associations 3298 * randomize the first poll over the minimum poll interval to 3299 * avoid implosion. 3300 */ 3301 peer->nextdate = peer->update = peer->outdate = current_time; 3302 if (initializing) { 3303 peer->nextdate += peer_associations; 3304 } else if (!(FLAG_CONFIG & peer->flags)) { 3305 peer->nextdate += ntp_minpkt + 1; 3306 /* space out manycastclient first polls */ 3307 if (peer->nextdate < earliest) { 3308 peer->nextdate = earliest; 3309 } 3310 earliest = peer->nextdate + 1; 3311 } else { 3312 peer->nextdate += ntp_random() % (1 << peer->minpoll); 3313 } 3314 #ifdef AUTOKEY 3315 peer->refresh = current_time + (1 << NTP_REFRESH); 3316 #endif /* AUTOKEY */ 3317 DPRINTF(1, ("peer_clear: at %ld next %ld associd %d refid %s\n", 3318 current_time, peer->nextdate, peer->associd, 3319 ident)); 3320 } 3321 3322 3323 /* 3324 * clock_filter - add incoming clock sample to filter register and run 3325 * the filter procedure to find the best sample. 3326 */ 3327 void 3328 clock_filter( 3329 struct peer *peer, /* peer structure pointer */ 3330 double sample_offset, /* clock offset */ 3331 double sample_delay, /* roundtrip delay */ 3332 double sample_disp /* dispersion */ 3333 ) 3334 { 3335 double dst[NTP_SHIFT]; /* distance vector */ 3336 u_char ord[NTP_SHIFT]; /* index vector */ 3337 short i, j; 3338 u_char k, m; 3339 double dtemp, etemp; 3340 3341 /* 3342 * A sample consists of the offset, delay, dispersion and epoch 3343 * of arrival. The offset and delay are determined by the on- 3344 * wire protocol. The dispersion grows from the last outbound 3345 * packet to the arrival of this one increased by the sum of the 3346 * peer precision and the system precision as required by the 3347 * error budget. First, shift the new arrival into the shift 3348 * register discarding the oldest one. 3349 */ 3350 j = peer->filter_nextpt; 3351 peer->filter_offset[j] = sample_offset; 3352 peer->filter_delay[j] = sample_delay; 3353 peer->filter_disp[j] = sample_disp; 3354 peer->filter_epoch[j] = current_time; 3355 j = (j + 1) % NTP_SHIFT; 3356 peer->filter_nextpt = (u_char)j; 3357 3358 /* 3359 * Update dispersions since the last update and at the same 3360 * time initialize the distance and index lists. Since samples 3361 * become increasingly uncorrelated beyond the Allan intercept, 3362 * only under exceptional cases will an older sample be used. 3363 * Therefore, the distance list uses a compound metric. If the 3364 * dispersion is greater than the maximum dispersion, clamp the 3365 * distance at that value. If the time since the last update is 3366 * less than the Allan intercept use the delay; otherwise, use 3367 * the sum of the delay and dispersion. 3368 */ 3369 dtemp = clock_phi * (current_time - peer->update); 3370 peer->update = current_time; 3371 for (i = NTP_SHIFT - 1; i >= 0; i--) { 3372 if (i != 0) 3373 peer->filter_disp[j] += dtemp; 3374 if (peer->filter_disp[j] >= MAXDISPERSE) { 3375 peer->filter_disp[j] = MAXDISPERSE; 3376 dst[i] = MAXDISPERSE; 3377 } else if (peer->update - peer->filter_epoch[j] > 3378 (u_long)ULOGTOD(allan_xpt)) { 3379 dst[i] = peer->filter_delay[j] + 3380 peer->filter_disp[j]; 3381 } else { 3382 dst[i] = peer->filter_delay[j]; 3383 } 3384 ord[i] = (u_char)j; 3385 j = (j + 1) % NTP_SHIFT; 3386 } 3387 3388 /* 3389 * If the clock has stabilized, sort the samples by distance. 3390 */ 3391 if (freq_cnt == 0) { 3392 for (i = 1; i < NTP_SHIFT; i++) { 3393 for (j = 0; j < i; j++) { 3394 if (dst[j] > dst[i]) { 3395 k = ord[j]; 3396 ord[j] = ord[i]; 3397 ord[i] = k; 3398 etemp = dst[j]; 3399 dst[j] = dst[i]; 3400 dst[i] = etemp; 3401 } 3402 } 3403 } 3404 } 3405 3406 /* 3407 * Copy the index list to the association structure so ntpq 3408 * can see it later. Prune the distance list to leave only 3409 * samples less than the maximum dispersion, which disfavors 3410 * uncorrelated samples older than the Allan intercept. To 3411 * further improve the jitter estimate, of the remainder leave 3412 * only samples less than the maximum distance, but keep at 3413 * least two samples for jitter calculation. 3414 */ 3415 m = 0; 3416 for (i = 0; i < NTP_SHIFT; i++) { 3417 peer->filter_order[i] = ord[i]; 3418 if ( dst[i] >= MAXDISPERSE 3419 || (m >= 2 && dst[i] >= sys_maxdist)) 3420 continue; 3421 m++; 3422 } 3423 3424 /* 3425 * Compute the dispersion and jitter. The dispersion is weighted 3426 * exponentially by NTP_FWEIGHT (0.5) so it is normalized close 3427 * to 1.0. The jitter is the RMS differences relative to the 3428 * lowest delay sample. 3429 */ 3430 peer->disp = peer->jitter = 0; 3431 k = ord[0]; 3432 for (i = NTP_SHIFT - 1; i >= 0; i--) { 3433 j = ord[i]; 3434 peer->disp = NTP_FWEIGHT * ( peer->disp 3435 + peer->filter_disp[j]); 3436 if (i < m) { 3437 peer->jitter += DIFF(peer->filter_offset[j], 3438 peer->filter_offset[k]); 3439 } 3440 } 3441 3442 /* 3443 * If no acceptable samples remain in the shift register, 3444 * quietly tiptoe home leaving only the dispersion. Otherwise, 3445 * save the offset, delay and jitter. Note the jitter must not 3446 * be less than the precision. 3447 */ 3448 if (0 == m) { 3449 clock_select(); 3450 return; 3451 } 3452 etemp = fabs(peer->offset - peer->filter_offset[k]); 3453 peer->offset = peer->filter_offset[k]; 3454 peer->delay = peer->filter_delay[k]; 3455 if (m > 1) { 3456 peer->jitter /= m - 1; 3457 } 3458 peer->jitter = max(SQRT(peer->jitter), LOGTOD(sys_precision)); 3459 3460 /* 3461 * If the the new sample and the current sample are both valid 3462 * and the difference between their offsets exceeds CLOCK_SGATE 3463 * (3) times the jitter and the interval between them is less 3464 * than twice the host poll interval, consider the new sample 3465 * a popcorn spike and ignore it. 3466 */ 3467 if ( peer->disp < sys_maxdist 3468 && peer->filter_disp[k] < sys_maxdist 3469 && etemp > CLOCK_SGATE * peer->jitter 3470 && peer->filter_epoch[k] - peer->epoch 3471 < 2. * ULOGTOD(peer->hpoll)) { 3472 mprintf_event(PEVNT_POPCORN, peer, "%.9f s", etemp); 3473 return; 3474 } 3475 3476 /* 3477 * A new minimum sample is useful only if it is later than the 3478 * last one used. In this design the maximum lifetime of any 3479 * sample is not greater than NTP_SHIFT (8) times the poll 3480 * interval, so the maximum interval between minimum samples is 3481 * NTP_SHIFT packets. 3482 */ 3483 if (peer->filter_epoch[k] <= peer->epoch) { 3484 DPRINTF(2, ("clock_filter: old sample %lu s\n", 3485 current_time - peer->filter_epoch[k])); 3486 return; 3487 } 3488 peer->epoch = peer->filter_epoch[k]; 3489 3490 /* 3491 * The mitigated sample statistics are saved for later 3492 * processing. If not synchronized or not in a burst, tickle the 3493 * clock select algorithm. 3494 */ 3495 record_peer_stats(&peer->srcadr, ctlpeerstatus(peer), peer->offset, 3496 peer->delay, peer->disp, peer->jitter); 3497 DPRINTF(1, ("clock_filter: n %hu off %.9f del %.9f dsp %.9f jit %.9f\n", 3498 (u_short)m, peer->offset, peer->delay, peer->disp, 3499 peer->jitter)); 3500 if (0 == peer->burst || LEAP_NOTINSYNC == sys_leap) { 3501 clock_select(); 3502 } 3503 } 3504 3505 3506 /* 3507 * clock_select - find the pick-of-the-litter clock 3508 * 3509 * LOCKCLOCK: (1) If the local clock is the prefer peer, it will always 3510 * be enabled, even if declared falseticker, (2) only the prefer peer 3511 * can be selected as the system peer, (3) if the external source is 3512 * down, the system leap bits are set to 11 and the stratum set to 3513 * infinity. 3514 */ 3515 void 3516 clock_select(void) 3517 { 3518 struct peer *peer; 3519 int i, j, k, n; 3520 int nlist, nl2; 3521 int allow; 3522 int speer; 3523 double d, e, f, g; 3524 double high, low; 3525 double speermet; 3526 double lastresort_dist = MAXDISPERSE; 3527 double orphmet = 2.0 * U_INT32_MAX; /* 2x is greater than */ 3528 struct endpoint endp; 3529 struct peer *osys_peer; 3530 struct peer *sys_prefer = NULL; /* prefer peer */ 3531 struct peer *typesystem = NULL; 3532 struct peer *typelastresort = NULL; 3533 struct peer *typeorphan = NULL; 3534 #ifdef REFCLOCK 3535 struct peer *typeacts = NULL; 3536 struct peer *typelocal = NULL; 3537 struct peer *typepps = NULL; 3538 #endif /* REFCLOCK */ 3539 static struct endpoint *endpoint = NULL; 3540 static int *indx = NULL; 3541 static peer_select *peers = NULL; 3542 static u_int endpoint_size = 0; 3543 static u_int peers_size = 0; 3544 static u_int indx_size = 0; 3545 size_t octets; 3546 3547 /* 3548 * Initialize and create endpoint, index and peer lists big 3549 * enough to handle all associations. 3550 */ 3551 osys_peer = sys_peer; 3552 sys_survivors = 0; 3553 #ifdef LOCKCLOCK 3554 set_sys_leap(LEAP_NOTINSYNC); 3555 sys_stratum = STRATUM_UNSPEC; 3556 memcpy(&sys_refid, "DOWN", 4); 3557 #endif /* LOCKCLOCK */ 3558 3559 /* 3560 * Allocate dynamic space depending on the number of 3561 * associations. 3562 */ 3563 nlist = 1; 3564 for (peer = peer_list; peer != NULL; peer = peer->p_link) 3565 nlist++; 3566 endpoint_size = ALIGNED_SIZE(nlist * 2 * sizeof(*endpoint)); 3567 peers_size = ALIGNED_SIZE(nlist * sizeof(*peers)); 3568 indx_size = ALIGNED_SIZE(nlist * 2 * sizeof(*indx)); 3569 octets = endpoint_size + peers_size + indx_size; 3570 endpoint = erealloc(endpoint, octets); 3571 peers = INC_ALIGNED_PTR(endpoint, endpoint_size); 3572 indx = INC_ALIGNED_PTR(peers, peers_size); 3573 3574 /* 3575 * Initially, we populate the island with all the rifraff peers 3576 * that happen to be lying around. Those with seriously 3577 * defective clocks are immediately booted off the island. Then, 3578 * the falsetickers are culled and put to sea. The truechimers 3579 * remaining are subject to repeated rounds where the most 3580 * unpopular at each round is kicked off. When the population 3581 * has dwindled to sys_minclock, the survivors split a million 3582 * bucks and collectively crank the chimes. 3583 */ 3584 nlist = nl2 = 0; /* none yet */ 3585 for (peer = peer_list; peer != NULL; peer = peer->p_link) { 3586 peer->new_status = CTL_PST_SEL_REJECT; 3587 3588 /* 3589 * Leave the island immediately if the peer is 3590 * unfit to synchronize. 3591 */ 3592 if (peer_unfit(peer)) { 3593 continue; 3594 } 3595 3596 /* 3597 * If we have never been synchronised, look for any peer 3598 * which has ever been synchronised and pick the one which 3599 * has the lowest root distance. This can be used as a last 3600 * resort if all else fails. Once we get an initial sync 3601 * with this peer, sys_reftime gets set and so this 3602 * function becomes disabled. 3603 */ 3604 if (L_ISZERO(&sys_reftime)) { 3605 d = root_distance(peer); 3606 if (!L_ISZERO(&peer->reftime) && d < lastresort_dist) { 3607 typelastresort = peer; 3608 lastresort_dist = d; 3609 } 3610 } 3611 3612 /* 3613 * If this peer is an orphan parent, elect the 3614 * one with the lowest metric defined as the 3615 * IPv4 address or the first 64 bits of the 3616 * hashed IPv6 address. To ensure convergence 3617 * on the same selected orphan, consider as 3618 * well that this system may have the lowest 3619 * metric and be the orphan parent. If this 3620 * system wins, sys_peer will be NULL to trigger 3621 * orphan mode in timer(). 3622 */ 3623 if (peer->stratum == sys_orphan) { 3624 u_int32 localmet; 3625 u_int32 peermet; 3626 3627 if (peer->dstadr != NULL) 3628 localmet = ntohl(peer->dstadr->addr_refid); 3629 else 3630 localmet = U_INT32_MAX; 3631 peermet = ntohl(addr2refid(&peer->srcadr)); 3632 if (peermet < localmet && peermet < orphmet) { 3633 typeorphan = peer; 3634 orphmet = peermet; 3635 } 3636 continue; 3637 } 3638 3639 /* 3640 * If this peer could have the orphan parent 3641 * as a synchronization ancestor, exclude it 3642 * from selection to avoid forming a 3643 * synchronization loop within the orphan mesh, 3644 * triggering stratum climb to infinity 3645 * instability. Peers at stratum higher than 3646 * the orphan stratum could have the orphan 3647 * parent in ancestry so are excluded. 3648 * See http://bugs.ntp.org/2050 3649 */ 3650 if (peer->stratum > sys_orphan) { 3651 continue; 3652 } 3653 #ifdef REFCLOCK 3654 /* 3655 * The following are special cases. We deal 3656 * with them later. 3657 */ 3658 if (!(peer->flags & FLAG_PREFER)) { 3659 switch (peer->refclktype) { 3660 case REFCLK_LOCALCLOCK: 3661 if ( current_time > orphwait 3662 && typelocal == NULL) 3663 typelocal = peer; 3664 continue; 3665 3666 case REFCLK_ACTS: 3667 if ( current_time > orphwait 3668 && typeacts == NULL) 3669 typeacts = peer; 3670 continue; 3671 } 3672 } 3673 #endif /* REFCLOCK */ 3674 3675 /* 3676 * If we get this far, the peer can stay on the 3677 * island, but does not yet have the immunity 3678 * idol. 3679 */ 3680 peer->new_status = CTL_PST_SEL_SANE; 3681 f = root_distance(peer); 3682 peers[nlist].peer = peer; 3683 peers[nlist].error = peer->jitter; 3684 peers[nlist].synch = f; 3685 nlist++; 3686 3687 /* 3688 * Insert each interval endpoint on the unsorted 3689 * endpoint[] list. 3690 */ 3691 e = peer->offset; 3692 endpoint[nl2].type = -1; /* lower end */ 3693 endpoint[nl2].val = e - f; 3694 nl2++; 3695 endpoint[nl2].type = 1; /* upper end */ 3696 endpoint[nl2].val = e + f; 3697 nl2++; 3698 } 3699 /* 3700 * Construct sorted indx[] of endpoint[] indexes ordered by 3701 * offset. 3702 */ 3703 for (i = 0; i < nl2; i++) 3704 indx[i] = i; 3705 for (i = 0; i < nl2; i++) { 3706 endp = endpoint[indx[i]]; 3707 e = endp.val; 3708 k = i; 3709 for (j = i + 1; j < nl2; j++) { 3710 endp = endpoint[indx[j]]; 3711 if (endp.val < e) { 3712 e = endp.val; 3713 k = j; 3714 } 3715 } 3716 if (k != i) { 3717 j = indx[k]; 3718 indx[k] = indx[i]; 3719 indx[i] = j; 3720 } 3721 } 3722 for (i = 0; i < nl2; i++) 3723 DPRINTF(3, ("select: endpoint %2d %.6f\n", 3724 endpoint[indx[i]].type, endpoint[indx[i]].val)); 3725 3726 /* 3727 * This is the actual algorithm that cleaves the truechimers 3728 * from the falsetickers. The original algorithm was described 3729 * in Keith Marzullo's dissertation, but has been modified for 3730 * better accuracy. 3731 * 3732 * Briefly put, we first assume there are no falsetickers, then 3733 * scan the candidate list first from the low end upwards and 3734 * then from the high end downwards. The scans stop when the 3735 * number of intersections equals the number of candidates less 3736 * the number of falsetickers. If this doesn't happen for a 3737 * given number of falsetickers, we bump the number of 3738 * falsetickers and try again. If the number of falsetickers 3739 * becomes equal to or greater than half the number of 3740 * candidates, the Albanians have won the Byzantine wars and 3741 * correct synchronization is not possible. 3742 * 3743 * Here, nlist is the number of candidates and allow is the 3744 * number of falsetickers. Upon exit, the truechimers are the 3745 * survivors with offsets not less than low and not greater than 3746 * high. There may be none of them. 3747 */ 3748 low = 1e9; 3749 high = -1e9; 3750 for (allow = 0; 2 * allow < nlist; allow++) { 3751 3752 /* 3753 * Bound the interval (low, high) as the smallest 3754 * interval containing points from the most sources. 3755 */ 3756 n = 0; 3757 for (i = 0; i < nl2; i++) { 3758 low = endpoint[indx[i]].val; 3759 n -= endpoint[indx[i]].type; 3760 if (n >= nlist - allow) 3761 break; 3762 } 3763 n = 0; 3764 for (j = nl2 - 1; j >= 0; j--) { 3765 high = endpoint[indx[j]].val; 3766 n += endpoint[indx[j]].type; 3767 if (n >= nlist - allow) 3768 break; 3769 } 3770 3771 /* 3772 * If an interval containing truechimers is found, stop. 3773 * If not, increase the number of falsetickers and go 3774 * around again. 3775 */ 3776 if (high > low) 3777 break; 3778 } 3779 3780 /* 3781 * Clustering algorithm. Whittle candidate list of falsetickers, 3782 * who leave the island immediately. The TRUE peer is always a 3783 * truechimer. We must leave at least one peer to collect the 3784 * million bucks. 3785 * 3786 * We assert the correct time is contained in the interval, but 3787 * the best offset estimate for the interval might not be 3788 * contained in the interval. For this purpose, a truechimer is 3789 * defined as the midpoint of an interval that overlaps the 3790 * intersection interval. 3791 */ 3792 j = 0; 3793 for (i = 0; i < nlist; i++) { 3794 double h; 3795 3796 peer = peers[i].peer; 3797 h = peers[i].synch; 3798 if (( high <= low 3799 || peer->offset + h < low 3800 || peer->offset - h > high 3801 ) && !(peer->flags & FLAG_TRUE)) 3802 continue; 3803 3804 #ifdef REFCLOCK 3805 /* 3806 * Eligible PPS peers must survive the intersection 3807 * algorithm. Use the first one found, but don't 3808 * include any of them in the cluster population. 3809 */ 3810 if (peer->flags & FLAG_PPS) { 3811 if (typepps == NULL) 3812 typepps = peer; 3813 if (!(peer->flags & FLAG_TSTAMP_PPS)) 3814 continue; 3815 } 3816 #endif /* REFCLOCK */ 3817 3818 if (j != i) 3819 peers[j] = peers[i]; 3820 j++; 3821 } 3822 nlist = j; 3823 3824 /* 3825 * If no survivors remain at this point, check if the modem 3826 * driver, local driver or orphan parent in that order. If so, 3827 * nominate the first one found as the only survivor. 3828 * Otherwise, give up and leave the island to the rats. 3829 */ 3830 if (nlist == 0) { 3831 peers[0].error = 0; 3832 peers[0].synch = sys_mindisp; 3833 #ifdef REFCLOCK 3834 if (typeacts != NULL) { 3835 peers[0].peer = typeacts; 3836 nlist = 1; 3837 } else if (typelocal != NULL) { 3838 peers[0].peer = typelocal; 3839 nlist = 1; 3840 } else 3841 #endif /* REFCLOCK */ 3842 if (typeorphan != NULL) { 3843 peers[0].peer = typeorphan; 3844 nlist = 1; 3845 } else if (typelastresort != NULL) { 3846 peers[0].peer = typelastresort; 3847 nlist = 1; 3848 } 3849 } 3850 3851 /* 3852 * Mark the candidates at this point as truechimers. 3853 */ 3854 for (i = 0; i < nlist; i++) { 3855 peers[i].peer->new_status = CTL_PST_SEL_SELCAND; 3856 DPRINTF(2, ("select: survivor %s %f\n", 3857 stoa(&peers[i].peer->srcadr), peers[i].synch)); 3858 } 3859 3860 /* 3861 * Now, vote outliers off the island by select jitter weighted 3862 * by root distance. Continue voting as long as there are more 3863 * than sys_minclock survivors and the select jitter of the peer 3864 * with the worst metric is greater than the minimum peer 3865 * jitter. Stop if we are about to discard a TRUE or PREFER 3866 * peer, who of course have the immunity idol. 3867 */ 3868 while (1) { 3869 d = 1e9; 3870 e = -1e9; 3871 g = 0; 3872 k = 0; 3873 for (i = 0; i < nlist; i++) { 3874 if (peers[i].error < d) 3875 d = peers[i].error; 3876 peers[i].seljit = 0; 3877 if (nlist > 1) { 3878 f = 0; 3879 for (j = 0; j < nlist; j++) 3880 f += DIFF(peers[j].peer->offset, 3881 peers[i].peer->offset); 3882 peers[i].seljit = SQRT(f / (nlist - 1)); 3883 } 3884 if (peers[i].seljit * peers[i].synch > e) { 3885 g = peers[i].seljit; 3886 e = peers[i].seljit * peers[i].synch; 3887 k = i; 3888 } 3889 } 3890 g = max(g, LOGTOD(sys_precision)); 3891 if ( nlist <= max(1, sys_minclock) 3892 || g <= d 3893 || ((FLAG_TRUE | FLAG_PREFER) & peers[k].peer->flags)) 3894 break; 3895 3896 DPRINTF(3, ("select: drop %s seljit %.9f jit %.9f\n", 3897 ntoa(&peers[k].peer->srcadr), g, d)); 3898 if (nlist > sys_maxclock) 3899 peers[k].peer->new_status = CTL_PST_SEL_EXCESS; 3900 for (j = k + 1; j < nlist; j++) 3901 peers[j - 1] = peers[j]; 3902 nlist--; 3903 } 3904 3905 /* 3906 * What remains is a list usually not greater than sys_minclock 3907 * peers. Note that unsynchronized peers cannot survive this 3908 * far. Count and mark these survivors. 3909 * 3910 * While at it, count the number of leap warning bits found. 3911 * This will be used later to vote the system leap warning bit. 3912 * If a leap warning bit is found on a reference clock, the vote 3913 * is always won. 3914 * 3915 * Choose the system peer using a hybrid metric composed of the 3916 * selection jitter scaled by the root distance augmented by 3917 * stratum scaled by sys_mindisp (.001 by default). The goal of 3918 * the small stratum factor is to avoid clockhop between a 3919 * reference clock and a network peer which has a refclock and 3920 * is using an older ntpd, which does not floor sys_rootdisp at 3921 * sys_mindisp. 3922 * 3923 * In contrast, ntpd 4.2.6 and earlier used stratum primarily 3924 * in selecting the system peer, using a weight of 1 second of 3925 * additional root distance per stratum. This heavy bias is no 3926 * longer appropriate, as the scaled root distance provides a 3927 * more rational metric carrying the cumulative error budget. 3928 */ 3929 e = 1e9; 3930 speer = 0; 3931 leap_vote_ins = 0; 3932 leap_vote_del = 0; 3933 for (i = 0; i < nlist; i++) { 3934 peer = peers[i].peer; 3935 peer->unreach = 0; 3936 peer->new_status = CTL_PST_SEL_SYNCCAND; 3937 sys_survivors++; 3938 if (peer->leap == LEAP_ADDSECOND) { 3939 if (peer->flags & FLAG_REFCLOCK) 3940 leap_vote_ins = nlist; 3941 else if (leap_vote_ins < nlist) 3942 leap_vote_ins++; 3943 } 3944 if (peer->leap == LEAP_DELSECOND) { 3945 if (peer->flags & FLAG_REFCLOCK) 3946 leap_vote_del = nlist; 3947 else if (leap_vote_del < nlist) 3948 leap_vote_del++; 3949 } 3950 if (peer->flags & FLAG_PREFER) 3951 sys_prefer = peer; 3952 speermet = peers[i].seljit * peers[i].synch + 3953 peer->stratum * sys_mindisp; 3954 if (speermet < e) { 3955 e = speermet; 3956 speer = i; 3957 } 3958 } 3959 3960 /* 3961 * Unless there are at least sys_misane survivors, leave the 3962 * building dark. Otherwise, do a clockhop dance. Ordinarily, 3963 * use the selected survivor speer. However, if the current 3964 * system peer is not speer, stay with the current system peer 3965 * as long as it doesn't get too old or too ugly. 3966 */ 3967 if (nlist > 0 && nlist >= sys_minsane) { 3968 double x; 3969 3970 typesystem = peers[speer].peer; 3971 if (osys_peer == NULL || osys_peer == typesystem) { 3972 sys_clockhop = 0; 3973 } else if ((x = fabs(typesystem->offset - 3974 osys_peer->offset)) < sys_mindisp) { 3975 if (0 == sys_clockhop) 3976 sys_clockhop = sys_mindisp; 3977 else 3978 sys_clockhop *= .5; 3979 DPRINTF(1, ("select: clockhop %d %.9f %.9f\n", 3980 j, x, sys_clockhop)); 3981 if (x < sys_clockhop) 3982 typesystem = osys_peer; 3983 else 3984 sys_clockhop = 0; 3985 } else { 3986 sys_clockhop = 0; 3987 } 3988 } 3989 3990 /* 3991 * Mitigation rules of the game. We have the pick of the 3992 * litter in typesystem if any survivors are left. If 3993 * there is a prefer peer, use its offset and jitter. 3994 * Otherwise, use the combined offset and jitter of all kitters. 3995 */ 3996 if (typesystem != NULL) { 3997 if (sys_prefer == NULL) { 3998 typesystem->new_status = CTL_PST_SEL_SYSPEER; 3999 clock_combine(peers, sys_survivors, speer); 4000 } else { 4001 typesystem = sys_prefer; 4002 sys_clockhop = 0; 4003 typesystem->new_status = CTL_PST_SEL_SYSPEER; 4004 sys_offset = typesystem->offset; 4005 sys_jitter = typesystem->jitter; 4006 } 4007 DPRINTF(1, ("select: combine offset %.9f jitter %.9f\n", 4008 sys_offset, sys_jitter)); 4009 } 4010 #ifdef REFCLOCK 4011 /* 4012 * If a PPS driver is lit and the combined offset is less than 4013 * 0.4 s, select the driver as the PPS peer and use its offset 4014 * and jitter. However, if this is the atom driver, use it only 4015 * if there is a prefer peer or there are no survivors and none 4016 * are required. 4017 */ 4018 if ( typepps != NULL 4019 && fabs(sys_offset) < 0.4 4020 && ( typepps->refclktype != REFCLK_ATOM_PPS 4021 || ( typepps->refclktype == REFCLK_ATOM_PPS 4022 && ( sys_prefer != NULL 4023 || (typesystem == NULL && sys_minsane == 0))))) { 4024 typesystem = typepps; 4025 sys_clockhop = 0; 4026 typesystem->new_status = CTL_PST_SEL_PPS; 4027 sys_offset = typesystem->offset; 4028 sys_jitter = typesystem->jitter; 4029 DPRINTF(1, ("select: pps offset %.9f jitter %.9f\n", 4030 sys_offset, sys_jitter)); 4031 } 4032 #endif /* REFCLOCK */ 4033 4034 /* 4035 * If there are no survivors at this point, there is no 4036 * system peer. If so and this is an old update, keep the 4037 * current statistics, but do not update the clock. 4038 */ 4039 if (typesystem == NULL) { 4040 if (osys_peer != NULL) { 4041 orphwait = current_time + sys_orphwait; 4042 report_event(EVNT_NOPEER, NULL, NULL); 4043 } 4044 sys_peer = NULL; 4045 for (peer = peer_list; peer != NULL; peer = peer->p_link) 4046 peer->status = peer->new_status; 4047 return; 4048 } 4049 4050 /* 4051 * Do not use old data, as this may mess up the clock discipline 4052 * stability. 4053 */ 4054 if (typesystem->epoch <= sys_epoch) 4055 return; 4056 4057 /* 4058 * We have found the alpha male. Wind the clock. 4059 */ 4060 if (osys_peer != typesystem) 4061 report_event(PEVNT_NEWPEER, typesystem, NULL); 4062 for (peer = peer_list; peer != NULL; peer = peer->p_link) 4063 peer->status = peer->new_status; 4064 clock_update(typesystem); 4065 } 4066 4067 4068 static void 4069 clock_combine( 4070 peer_select * peers, /* survivor list */ 4071 int npeers, /* number of survivors */ 4072 int syspeer /* index of sys.peer */ 4073 ) 4074 { 4075 int i; 4076 double x, y, z, w; 4077 4078 y = z = w = 0; 4079 for (i = 0; i < npeers; i++) { 4080 x = 1. / peers[i].synch; 4081 y += x; 4082 z += x * peers[i].peer->offset; 4083 w += x * DIFF(peers[i].peer->offset, 4084 peers[syspeer].peer->offset); 4085 } 4086 sys_offset = z / y; 4087 sys_jitter = SQRT(w / y + SQUARE(peers[syspeer].seljit)); 4088 } 4089 4090 4091 /* 4092 * root_distance - compute synchronization distance from peer to root 4093 */ 4094 static double 4095 root_distance( 4096 struct peer *peer /* peer structure pointer */ 4097 ) 4098 { 4099 double dtemp; 4100 4101 /* 4102 * Root Distance (LAMBDA) is defined as: 4103 * (delta + DELTA)/2 + epsilon + EPSILON + D 4104 * 4105 * where: 4106 * delta is the round-trip delay 4107 * DELTA is the root delay 4108 * epsilon is the peer dispersion 4109 * + (15 usec each second) 4110 * EPSILON is the root dispersion 4111 * D is sys_jitter 4112 * 4113 * NB: Think hard about why we are using these values, and what 4114 * the alternatives are, and the various pros/cons. 4115 * 4116 * DLM thinks these are probably the best choices from any of the 4117 * other worse choices. 4118 */ 4119 dtemp = (peer->delay + peer->rootdelay) / 2 4120 + peer->disp 4121 + clock_phi * (current_time - peer->update) 4122 + peer->rootdisp 4123 + peer->jitter; 4124 /* 4125 * Careful squeak here. The value returned must be greater than 4126 * the minimum root dispersion in order to avoid clockhop with 4127 * highly precise reference clocks. Note that the root distance 4128 * cannot exceed the sys_maxdist, as this is the cutoff by the 4129 * selection algorithm. 4130 */ 4131 if (dtemp < sys_mindisp) 4132 dtemp = sys_mindisp; 4133 return (dtemp); 4134 } 4135 4136 4137 /* 4138 * peer_xmit - send packet for persistent association. 4139 */ 4140 static void 4141 peer_xmit( 4142 struct peer *peer /* peer structure pointer */ 4143 ) 4144 { 4145 struct pkt xpkt; /* transmit packet */ 4146 size_t sendlen, authlen; 4147 keyid_t xkeyid = 0; /* transmit key ID */ 4148 l_fp xmt_tx, xmt_ty; 4149 4150 if (!peer->dstadr) { /* can't send */ 4151 return; 4152 } 4153 xpkt.li_vn_mode = PKT_LI_VN_MODE(sys_leap, peer->version, 4154 peer->hmode); 4155 xpkt.stratum = STRATUM_TO_PKT(sys_stratum); 4156 xpkt.ppoll = peer->hpoll; 4157 xpkt.precision = sys_precision; 4158 xpkt.refid = sys_refid; 4159 xpkt.rootdelay = HTONS_FP(DTOFP(sys_rootdelay)); 4160 xpkt.rootdisp = HTONS_FP(DTOUFP(sys_rootdisp)); 4161 /* Use sys_reftime for peer exchanges */ 4162 HTONL_FP(&sys_reftime, &xpkt.reftime); 4163 HTONL_FP(&peer->rec, &xpkt.org); 4164 HTONL_FP(&peer->dst, &xpkt.rec); 4165 4166 /* 4167 * If the received packet contains a MAC, the transmitted packet 4168 * is authenticated and contains a MAC. If not, the transmitted 4169 * packet is not authenticated. 4170 * 4171 * It is most important when autokey is in use that the local 4172 * interface IP address be known before the first packet is 4173 * sent. Otherwise, it is not possible to compute a correct MAC 4174 * the recipient will accept. Thus, the I/O semantics have to do 4175 * a little more work. In particular, the wildcard interface 4176 * might not be usable. 4177 */ 4178 sendlen = LEN_PKT_NOMAC; 4179 if ( 4180 #ifdef AUTOKEY 4181 !(peer->flags & FLAG_SKEY) && 4182 #endif /* !AUTOKEY */ 4183 peer->keyid == 0) { 4184 4185 /* 4186 * Transmit a-priori timestamps 4187 */ 4188 get_systime(&xmt_tx); 4189 if (peer->flip == 0) { /* basic mode */ 4190 peer->aorg = xmt_tx; 4191 HTONL_FP(&xmt_tx, &xpkt.xmt); 4192 } else { /* interleaved modes */ 4193 if (peer->hmode == MODE_BROADCAST) { /* bcst */ 4194 HTONL_FP(&xmt_tx, &xpkt.xmt); 4195 if (peer->flip > 0) 4196 HTONL_FP(&peer->borg, 4197 &xpkt.org); 4198 else 4199 HTONL_FP(&peer->aorg, 4200 &xpkt.org); 4201 } else { /* symmetric */ 4202 if (peer->flip > 0) 4203 HTONL_FP(&peer->borg, 4204 &xpkt.xmt); 4205 else 4206 HTONL_FP(&peer->aorg, 4207 &xpkt.xmt); 4208 } 4209 } 4210 peer->t21_bytes = sendlen; 4211 sendpkt(&peer->srcadr, peer->dstadr, 4212 sys_ttl[(peer->ttl >= sys_ttlmax) ? sys_ttlmax : peer->ttl], 4213 &xpkt, sendlen); 4214 peer->sent++; 4215 peer->throttle += (1 << peer->minpoll) - 2; 4216 4217 /* 4218 * Capture a-posteriori timestamps 4219 */ 4220 get_systime(&xmt_ty); 4221 if (peer->flip != 0) { /* interleaved modes */ 4222 if (peer->flip > 0) 4223 peer->aorg = xmt_ty; 4224 else 4225 peer->borg = xmt_ty; 4226 peer->flip = -peer->flip; 4227 } 4228 L_SUB(&xmt_ty, &xmt_tx); 4229 LFPTOD(&xmt_ty, peer->xleave); 4230 DPRINTF(1, ("peer_xmit: at %ld %s->%s mode %d len %zu xmt 0x%x.%08x\n", 4231 current_time, latoa(peer->dstadr), 4232 stoa(&peer->srcadr), peer->hmode, sendlen, 4233 xmt_tx.l_ui, xmt_tx.l_uf)); 4234 return; 4235 } 4236 4237 /* 4238 * Authentication is enabled, so the transmitted packet must be 4239 * authenticated. If autokey is enabled, fuss with the various 4240 * modes; otherwise, symmetric key cryptography is used. 4241 */ 4242 #ifdef AUTOKEY 4243 if (peer->flags & FLAG_SKEY) { 4244 struct exten *exten; /* extension field */ 4245 4246 /* 4247 * The Public Key Dance (PKD): Cryptographic credentials 4248 * are contained in extension fields, each including a 4249 * 4-octet length/code word followed by a 4-octet 4250 * association ID and optional additional data. Optional 4251 * data includes a 4-octet data length field followed by 4252 * the data itself. Request messages are sent from a 4253 * configured association; response messages can be sent 4254 * from a configured association or can take the fast 4255 * path without ever matching an association. Response 4256 * messages have the same code as the request, but have 4257 * a response bit and possibly an error bit set. In this 4258 * implementation, a message may contain no more than 4259 * one command and one or more responses. 4260 * 4261 * Cryptographic session keys include both a public and 4262 * a private componet. Request and response messages 4263 * using extension fields are always sent with the 4264 * private component set to zero. Packets without 4265 * extension fields indlude the private component when 4266 * the session key is generated. 4267 */ 4268 while (1) { 4269 4270 /* 4271 * Allocate and initialize a keylist if not 4272 * already done. Then, use the list in inverse 4273 * order, discarding keys once used. Keep the 4274 * latest key around until the next one, so 4275 * clients can use client/server packets to 4276 * compute propagation delay. 4277 * 4278 * Note that once a key is used from the list, 4279 * it is retained in the key cache until the 4280 * next key is used. This is to allow a client 4281 * to retrieve the encrypted session key 4282 * identifier to verify authenticity. 4283 * 4284 * If for some reason a key is no longer in the 4285 * key cache, a birthday has happened or the key 4286 * has expired, so the pseudo-random sequence is 4287 * broken. In that case, purge the keylist and 4288 * regenerate it. 4289 */ 4290 if (peer->keynumber == 0) 4291 make_keylist(peer, peer->dstadr); 4292 else 4293 peer->keynumber--; 4294 xkeyid = peer->keylist[peer->keynumber]; 4295 if (authistrusted(xkeyid)) 4296 break; 4297 else 4298 key_expire(peer); 4299 } 4300 peer->keyid = xkeyid; 4301 exten = NULL; 4302 switch (peer->hmode) { 4303 4304 /* 4305 * In broadcast server mode the autokey values are 4306 * required by the broadcast clients. Push them when a 4307 * new keylist is generated; otherwise, push the 4308 * association message so the client can request them at 4309 * other times. 4310 */ 4311 case MODE_BROADCAST: 4312 if (peer->flags & FLAG_ASSOC) 4313 exten = crypto_args(peer, CRYPTO_AUTO | 4314 CRYPTO_RESP, peer->associd, NULL); 4315 else 4316 exten = crypto_args(peer, CRYPTO_ASSOC | 4317 CRYPTO_RESP, peer->associd, NULL); 4318 break; 4319 4320 /* 4321 * In symmetric modes the parameter, certificate, 4322 * identity, cookie and autokey exchanges are 4323 * required. The leapsecond exchange is optional. But, a 4324 * peer will not believe the other peer until the other 4325 * peer has synchronized, so the certificate exchange 4326 * might loop until then. If a peer finds a broken 4327 * autokey sequence, it uses the autokey exchange to 4328 * retrieve the autokey values. In any case, if a new 4329 * keylist is generated, the autokey values are pushed. 4330 */ 4331 case MODE_ACTIVE: 4332 case MODE_PASSIVE: 4333 4334 /* 4335 * Parameter, certificate and identity. 4336 */ 4337 if (!peer->crypto) 4338 exten = crypto_args(peer, CRYPTO_ASSOC, 4339 peer->associd, hostval.ptr); 4340 else if (!(peer->crypto & CRYPTO_FLAG_CERT)) 4341 exten = crypto_args(peer, CRYPTO_CERT, 4342 peer->associd, peer->issuer); 4343 else if (!(peer->crypto & CRYPTO_FLAG_VRFY)) 4344 exten = crypto_args(peer, 4345 crypto_ident(peer), peer->associd, 4346 NULL); 4347 4348 /* 4349 * Cookie and autokey. We request the cookie 4350 * only when the this peer and the other peer 4351 * are synchronized. But, this peer needs the 4352 * autokey values when the cookie is zero. Any 4353 * time we regenerate the key list, we offer the 4354 * autokey values without being asked. If for 4355 * some reason either peer finds a broken 4356 * autokey sequence, the autokey exchange is 4357 * used to retrieve the autokey values. 4358 */ 4359 else if ( sys_leap != LEAP_NOTINSYNC 4360 && peer->leap != LEAP_NOTINSYNC 4361 && !(peer->crypto & CRYPTO_FLAG_COOK)) 4362 exten = crypto_args(peer, CRYPTO_COOK, 4363 peer->associd, NULL); 4364 else if (!(peer->crypto & CRYPTO_FLAG_AUTO)) 4365 exten = crypto_args(peer, CRYPTO_AUTO, 4366 peer->associd, NULL); 4367 else if ( peer->flags & FLAG_ASSOC 4368 && peer->crypto & CRYPTO_FLAG_SIGN) 4369 exten = crypto_args(peer, CRYPTO_AUTO | 4370 CRYPTO_RESP, peer->assoc, NULL); 4371 4372 /* 4373 * Wait for clock sync, then sign the 4374 * certificate and retrieve the leapsecond 4375 * values. 4376 */ 4377 else if (sys_leap == LEAP_NOTINSYNC) 4378 break; 4379 4380 else if (!(peer->crypto & CRYPTO_FLAG_SIGN)) 4381 exten = crypto_args(peer, CRYPTO_SIGN, 4382 peer->associd, hostval.ptr); 4383 else if (!(peer->crypto & CRYPTO_FLAG_LEAP)) 4384 exten = crypto_args(peer, CRYPTO_LEAP, 4385 peer->associd, NULL); 4386 break; 4387 4388 /* 4389 * In client mode the parameter, certificate, identity, 4390 * cookie and sign exchanges are required. The 4391 * leapsecond exchange is optional. If broadcast client 4392 * mode the same exchanges are required, except that the 4393 * autokey exchange is substitutes for the cookie 4394 * exchange, since the cookie is always zero. If the 4395 * broadcast client finds a broken autokey sequence, it 4396 * uses the autokey exchange to retrieve the autokey 4397 * values. 4398 */ 4399 case MODE_CLIENT: 4400 4401 /* 4402 * Parameter, certificate and identity. 4403 */ 4404 if (!peer->crypto) 4405 exten = crypto_args(peer, CRYPTO_ASSOC, 4406 peer->associd, hostval.ptr); 4407 else if (!(peer->crypto & CRYPTO_FLAG_CERT)) 4408 exten = crypto_args(peer, CRYPTO_CERT, 4409 peer->associd, peer->issuer); 4410 else if (!(peer->crypto & CRYPTO_FLAG_VRFY)) 4411 exten = crypto_args(peer, 4412 crypto_ident(peer), peer->associd, 4413 NULL); 4414 4415 /* 4416 * Cookie and autokey. These are requests, but 4417 * we use the peer association ID with autokey 4418 * rather than our own. 4419 */ 4420 else if (!(peer->crypto & CRYPTO_FLAG_COOK)) 4421 exten = crypto_args(peer, CRYPTO_COOK, 4422 peer->associd, NULL); 4423 else if (!(peer->crypto & CRYPTO_FLAG_AUTO)) 4424 exten = crypto_args(peer, CRYPTO_AUTO, 4425 peer->assoc, NULL); 4426 4427 /* 4428 * Wait for clock sync, then sign the 4429 * certificate and retrieve the leapsecond 4430 * values. 4431 */ 4432 else if (sys_leap == LEAP_NOTINSYNC) 4433 break; 4434 4435 else if (!(peer->crypto & CRYPTO_FLAG_SIGN)) 4436 exten = crypto_args(peer, CRYPTO_SIGN, 4437 peer->associd, hostval.ptr); 4438 else if (!(peer->crypto & CRYPTO_FLAG_LEAP)) 4439 exten = crypto_args(peer, CRYPTO_LEAP, 4440 peer->associd, NULL); 4441 break; 4442 } 4443 4444 /* 4445 * Add a queued extension field if present. This is 4446 * always a request message, so the reply ID is already 4447 * in the message. If an error occurs, the error bit is 4448 * lit in the response. 4449 */ 4450 if (peer->cmmd != NULL) { 4451 u_int32 temp32; 4452 4453 temp32 = CRYPTO_RESP; 4454 peer->cmmd->opcode |= htonl(temp32); 4455 sendlen += crypto_xmit(peer, &xpkt, NULL, 4456 sendlen, peer->cmmd, 0); 4457 free(peer->cmmd); 4458 peer->cmmd = NULL; 4459 } 4460 4461 /* 4462 * Add an extension field created above. All but the 4463 * autokey response message are request messages. 4464 */ 4465 if (exten != NULL) { 4466 if (exten->opcode != 0) 4467 sendlen += crypto_xmit(peer, &xpkt, 4468 NULL, sendlen, exten, 0); 4469 free(exten); 4470 } 4471 4472 /* 4473 * Calculate the next session key. Since extension 4474 * fields are present, the cookie value is zero. 4475 */ 4476 if (sendlen > (int)LEN_PKT_NOMAC) { 4477 session_key(&peer->dstadr->sin, &peer->srcadr, 4478 xkeyid, 0, 2); 4479 } 4480 } 4481 #endif /* AUTOKEY */ 4482 4483 /* 4484 * Transmit a-priori timestamps 4485 */ 4486 get_systime(&xmt_tx); 4487 if (peer->flip == 0) { /* basic mode */ 4488 peer->aorg = xmt_tx; 4489 HTONL_FP(&xmt_tx, &xpkt.xmt); 4490 } else { /* interleaved modes */ 4491 if (peer->hmode == MODE_BROADCAST) { /* bcst */ 4492 HTONL_FP(&xmt_tx, &xpkt.xmt); 4493 if (peer->flip > 0) 4494 HTONL_FP(&peer->borg, &xpkt.org); 4495 else 4496 HTONL_FP(&peer->aorg, &xpkt.org); 4497 } else { /* symmetric */ 4498 if (peer->flip > 0) 4499 HTONL_FP(&peer->borg, &xpkt.xmt); 4500 else 4501 HTONL_FP(&peer->aorg, &xpkt.xmt); 4502 } 4503 } 4504 xkeyid = peer->keyid; 4505 authlen = authencrypt(xkeyid, (u_int32 *)&xpkt, sendlen); 4506 if (authlen == 0) { 4507 report_event(PEVNT_AUTH, peer, "no key"); 4508 peer->flash |= TEST5; /* auth error */ 4509 peer->badauth++; 4510 return; 4511 } 4512 sendlen += authlen; 4513 #ifdef AUTOKEY 4514 if (xkeyid > NTP_MAXKEY) 4515 authtrust(xkeyid, 0); 4516 #endif /* AUTOKEY */ 4517 if (sendlen > sizeof(xpkt)) { 4518 msyslog(LOG_ERR, "peer_xmit: buffer overflow %u", (u_int)sendlen); 4519 exit(EX_SOFTWARE); 4520 } 4521 peer->t21_bytes = sendlen; 4522 sendpkt(&peer->srcadr, peer->dstadr, 4523 sys_ttl[(peer->ttl >= sys_ttlmax) ? sys_ttlmax : peer->ttl], 4524 &xpkt, sendlen); 4525 peer->sent++; 4526 peer->throttle += (1 << peer->minpoll) - 2; 4527 4528 /* 4529 * Capture a-posteriori timestamps 4530 */ 4531 get_systime(&xmt_ty); 4532 if (peer->flip != 0) { /* interleaved modes */ 4533 if (peer->flip > 0) 4534 peer->aorg = xmt_ty; 4535 else 4536 peer->borg = xmt_ty; 4537 peer->flip = -peer->flip; 4538 } 4539 L_SUB(&xmt_ty, &xmt_tx); 4540 LFPTOD(&xmt_ty, peer->xleave); 4541 #ifdef AUTOKEY 4542 DPRINTF(1, ("peer_xmit: at %ld %s->%s mode %d keyid %08x len %zu index %d\n", 4543 current_time, latoa(peer->dstadr), stoa(&peer->srcadr), 4544 peer->hmode, xkeyid, sendlen, peer->keynumber)); 4545 #else /* !AUTOKEY follows */ 4546 DPRINTF(1, ("peer_xmit: at %ld %s->%s mode %d keyid %08x len %zu\n", 4547 current_time, peer->dstadr ? 4548 ntoa(&peer->dstadr->sin) : "-", 4549 ntoa(&peer->srcadr), peer->hmode, xkeyid, sendlen)); 4550 #endif /* !AUTOKEY */ 4551 4552 return; 4553 } 4554 4555 4556 #ifdef LEAP_SMEAR 4557 4558 static void 4559 leap_smear_add_offs( 4560 l_fp *t, 4561 l_fp *t_recv 4562 ) 4563 { 4564 4565 L_ADD(t, &leap_smear.offset); 4566 4567 /* 4568 ** XXX: Should the smear be added to the root dispersion? 4569 */ 4570 4571 return; 4572 } 4573 4574 #endif /* LEAP_SMEAR */ 4575 4576 4577 /* 4578 * fast_xmit - Send packet for nonpersistent association. Note that 4579 * neither the source or destination can be a broadcast address. 4580 */ 4581 static void 4582 fast_xmit( 4583 struct recvbuf* rbufp, /* receive packet pointer */ 4584 int xmode, /* receive mode */ /* XXX: HMS: really? */ 4585 keyid_t xkeyid, /* transmit key ID */ 4586 int flags /* restrict mask */ 4587 ) 4588 { 4589 struct pkt xpkt; /* transmit packet structure */ 4590 struct pkt* rpkt; /* receive packet structure */ 4591 l_fp xmt_tx, xmt_ty; 4592 size_t sendlen; 4593 #ifdef AUTOKEY 4594 u_int32 temp32; 4595 #endif 4596 4597 /* 4598 * Initialize transmit packet header fields from the receive 4599 * buffer provided. We leave the fields intact as received, but 4600 * set the peer poll at the maximum of the receive peer poll and 4601 * the system minimum poll (ntp_minpoll). This is for KoD rate 4602 * control and not strictly specification compliant, but doesn't 4603 * break anything. 4604 */ 4605 rpkt = &rbufp->recv_pkt; 4606 /* 4607 * If the packet was received on an endpoint open only on 4608 * a multicast address, the response needs to go out from 4609 * a unicast endpoint. 4610 */ 4611 #ifndef MULTICAST_NONEWSOCKET 4612 if (rbufp->dstadr->flags & INT_MCASTOPEN) { 4613 rbufp->dstadr = findinterface(&rbufp->recv_srcadr); 4614 if (NULL == rbufp->dstadr || 4615 ANY_INTERFACE_CHOOSE(&rbufp->recv_srcadr) /* wildcard */ 4616 == rbufp->dstadr) { 4617 DPRINTF(2, ("No unicast local address found for" 4618 " reply to %s mcast.", 4619 stoa(&rbufp->recv_srcadr))); 4620 return; 4621 } 4622 } 4623 #endif 4624 4625 /* 4626 * If this is a kiss-o'-death (KoD) packet, show leap 4627 * unsynchronized, stratum zero, reference ID the four-character 4628 * kiss code and (???) system root delay. Note we don't reveal 4629 * the local time, so these packets can't be used for 4630 * synchronization. 4631 */ 4632 if (flags & RES_KOD) { 4633 sys_kodsent++; 4634 xpkt.li_vn_mode = PKT_LI_VN_MODE(LEAP_NOTINSYNC, 4635 PKT_VERSION(rpkt->li_vn_mode), xmode); 4636 xpkt.stratum = STRATUM_PKT_UNSPEC; 4637 xpkt.ppoll = max(rpkt->ppoll, ntp_minpoll); 4638 xpkt.precision = rpkt->precision; 4639 memcpy(&xpkt.refid, "RATE", 4); 4640 xpkt.rootdelay = rpkt->rootdelay; 4641 xpkt.rootdisp = rpkt->rootdisp; 4642 xpkt.reftime = rpkt->reftime; 4643 xpkt.org = rpkt->xmt; 4644 xpkt.rec = rpkt->xmt; 4645 xpkt.xmt = rpkt->xmt; 4646 4647 /* 4648 * This is a normal packet. Use the system variables. 4649 */ 4650 } else { 4651 double this_rootdisp; 4652 l_fp this_ref_time; 4653 4654 #ifdef LEAP_SMEAR 4655 /* 4656 * Make copies of the variables which can be affected by smearing. 4657 */ 4658 l_fp this_recv_time; 4659 #endif 4660 4661 /* 4662 * If we are inside the leap smear interval we add 4663 * the current smear offset to: 4664 * - the packet receive time, 4665 * - the packet transmit time, 4666 * - and eventually to the reftime to make sure the 4667 * reftime isn't later than the transmit/receive times. 4668 */ 4669 xpkt.li_vn_mode = PKT_LI_VN_MODE(xmt_leap, 4670 PKT_VERSION(rpkt->li_vn_mode), xmode); 4671 4672 xpkt.stratum = STRATUM_TO_PKT(sys_stratum); 4673 xpkt.ppoll = max(rpkt->ppoll, ntp_minpoll); 4674 xpkt.precision = sys_precision; 4675 xpkt.refid = sys_refid; 4676 xpkt.rootdelay = HTONS_FP(DTOFP(sys_rootdelay)); 4677 4678 /* 4679 ** Server Response Fuzzing 4680 ** 4681 ** Which values do we want to use for reftime and rootdisp? 4682 */ 4683 4684 if ( MODE_SERVER == xmode 4685 && RES_SRVRSPFUZ & flags) { 4686 if (current_time < p2_time) { 4687 this_ref_time = p2_reftime; 4688 this_rootdisp = p2_rootdisp; 4689 } else if (current_time < prev_time) { 4690 this_ref_time = prev_reftime; 4691 this_rootdisp = prev_rootdisp; 4692 } else { 4693 this_ref_time = sys_reftime; 4694 this_rootdisp = sys_rootdisp; 4695 } 4696 4697 SRVRSP_FUZZ(this_ref_time); 4698 } else { 4699 this_ref_time = sys_reftime; 4700 this_rootdisp = sys_rootdisp; 4701 } 4702 4703 /* 4704 ** ROOT DISPERSION 4705 */ 4706 4707 xpkt.rootdisp = HTONS_FP(DTOUFP(this_rootdisp)); 4708 4709 /* 4710 ** REFTIME 4711 */ 4712 4713 #ifdef LEAP_SMEAR 4714 if (leap_smear.in_progress) { 4715 /* adjust the reftime by the same amount as the 4716 * leap smear, as we don't want to risk the 4717 * reftime being later than the transmit time. 4718 */ 4719 leap_smear_add_offs(&this_ref_time, NULL); 4720 } 4721 #endif 4722 4723 HTONL_FP(&this_ref_time, &xpkt.reftime); 4724 4725 /* 4726 ** REFID 4727 */ 4728 4729 #ifdef LEAP_SMEAR 4730 if (leap_smear.in_progress) { 4731 xpkt.refid = convertLFPToRefID(leap_smear.offset); 4732 DPRINTF(2, ("fast_xmit: leap_smear.in_progress: refid %8x, smear %s\n", 4733 ntohl(xpkt.refid), 4734 lfptoa(&leap_smear.offset, 8) 4735 )); 4736 } 4737 #endif 4738 4739 /* 4740 ** ORIGIN 4741 */ 4742 4743 xpkt.org = rpkt->xmt; 4744 4745 /* 4746 ** RECEIVE 4747 */ 4748 #ifdef LEAP_SMEAR 4749 this_recv_time = rbufp->recv_time; 4750 if (leap_smear.in_progress) 4751 leap_smear_add_offs(&this_recv_time, NULL); 4752 HTONL_FP(&this_recv_time, &xpkt.rec); 4753 #else 4754 HTONL_FP(&rbufp->recv_time, &xpkt.rec); 4755 #endif 4756 4757 /* 4758 ** TRANSMIT 4759 */ 4760 4761 get_systime(&xmt_tx); 4762 #ifdef LEAP_SMEAR 4763 if (leap_smear.in_progress) 4764 leap_smear_add_offs(&xmt_tx, &this_recv_time); 4765 #endif 4766 HTONL_FP(&xmt_tx, &xpkt.xmt); 4767 } 4768 4769 #ifdef HAVE_NTP_SIGND 4770 if (flags & RES_MSSNTP) { 4771 send_via_ntp_signd(rbufp, xmode, xkeyid, flags, &xpkt); 4772 return; 4773 } 4774 #endif /* HAVE_NTP_SIGND */ 4775 4776 /* 4777 * If the received packet contains a MAC, the transmitted packet 4778 * is authenticated and contains a MAC. If not, the transmitted 4779 * packet is not authenticated. 4780 */ 4781 sendlen = LEN_PKT_NOMAC; 4782 if ((size_t)rbufp->recv_length == sendlen) { 4783 sendpkt(&rbufp->recv_srcadr, rbufp->dstadr, 0, &xpkt, 4784 sendlen); 4785 DPRINTF(1, ("fast_xmit: at %ld %s->%s mode %d len %lu\n", 4786 current_time, stoa(&rbufp->dstadr->sin), 4787 stoa(&rbufp->recv_srcadr), xmode, 4788 (u_long)sendlen)); 4789 return; 4790 } 4791 4792 /* 4793 * The received packet contains a MAC, so the transmitted packet 4794 * must be authenticated. For symmetric key cryptography, use 4795 * the predefined and trusted symmetric keys to generate the 4796 * cryptosum. For autokey cryptography, use the server private 4797 * value to generate the cookie, which is unique for every 4798 * source-destination-key ID combination. 4799 */ 4800 #ifdef AUTOKEY 4801 if (xkeyid > NTP_MAXKEY) { 4802 keyid_t cookie; 4803 4804 /* 4805 * The only way to get here is a reply to a legitimate 4806 * client request message, so the mode must be 4807 * MODE_SERVER. If an extension field is present, there 4808 * can be only one and that must be a command. Do what 4809 * needs, but with private value of zero so the poor 4810 * jerk can decode it. If no extension field is present, 4811 * use the cookie to generate the session key. 4812 */ 4813 cookie = session_key(&rbufp->recv_srcadr, 4814 &rbufp->dstadr->sin, 0, sys_private, 0); 4815 if ((size_t)rbufp->recv_length > sendlen + MAX_MAC_LEN) { 4816 session_key(&rbufp->dstadr->sin, 4817 &rbufp->recv_srcadr, xkeyid, 0, 2); 4818 temp32 = CRYPTO_RESP; 4819 rpkt->exten[0] |= htonl(temp32); 4820 sendlen += crypto_xmit(NULL, &xpkt, rbufp, 4821 sendlen, (struct exten *)rpkt->exten, 4822 cookie); 4823 } else { 4824 session_key(&rbufp->dstadr->sin, 4825 &rbufp->recv_srcadr, xkeyid, cookie, 2); 4826 } 4827 } 4828 #endif /* AUTOKEY */ 4829 get_systime(&xmt_tx); 4830 sendlen += authencrypt(xkeyid, (u_int32 *)&xpkt, sendlen); 4831 #ifdef AUTOKEY 4832 if (xkeyid > NTP_MAXKEY) 4833 authtrust(xkeyid, 0); 4834 #endif /* AUTOKEY */ 4835 sendpkt(&rbufp->recv_srcadr, rbufp->dstadr, 0, &xpkt, sendlen); 4836 get_systime(&xmt_ty); 4837 L_SUB(&xmt_ty, &xmt_tx); 4838 sys_authdelay = xmt_ty; 4839 DPRINTF(1, ("fast_xmit: at %ld %s->%s mode %d keyid %08x len %lu\n", 4840 current_time, ntoa(&rbufp->dstadr->sin), 4841 ntoa(&rbufp->recv_srcadr), xmode, xkeyid, 4842 (u_long)sendlen)); 4843 } 4844 4845 4846 /* 4847 * pool_xmit - resolve hostname or send unicast solicitation for pool. 4848 */ 4849 static void 4850 pool_xmit( 4851 struct peer *pool /* pool solicitor association */ 4852 ) 4853 { 4854 #ifdef WORKER 4855 struct pkt xpkt; /* transmit packet structure */ 4856 struct addrinfo hints; 4857 int rc; 4858 endpt * lcladr; 4859 sockaddr_u * rmtadr; 4860 u_short af; 4861 struct peer * p; 4862 l_fp xmt_tx; 4863 4864 DEBUG_REQUIRE(pool); 4865 if (NULL == pool->ai) { 4866 if (pool->addrs != NULL) { 4867 /* free() is used with copy_addrinfo_list() */ 4868 free(pool->addrs); 4869 pool->addrs = NULL; 4870 } 4871 af = AF(&pool->srcadr); 4872 if ( (AF_INET == af && !nonlocal_v4_addr_up) 4873 || (AF_INET6 == af && !nonlocal_v6_addr_up) 4874 || ( AF_UNSPEC == af 4875 && !nonlocal_v4_addr_up 4876 && !nonlocal_v6_addr_up)) { 4877 4878 /* POOL DNS query would be useless [Bug 3845] */ 4879 return; 4880 } 4881 ZERO(hints); 4882 hints.ai_family = AF(&pool->srcadr); 4883 hints.ai_socktype = SOCK_DGRAM; 4884 hints.ai_protocol = IPPROTO_UDP; 4885 /* ignore getaddrinfo_sometime() errors, we will retry */ 4886 rc = getaddrinfo_sometime( 4887 pool->hostname, 4888 "ntp", 4889 &hints, 4890 0, /* no retry */ 4891 &pool_name_resolved, 4892 (void *)(intptr_t)pool->associd); 4893 if (!rc) 4894 DPRINTF(1, ("pool DNS lookup %s started\n", 4895 pool->hostname)); 4896 else 4897 msyslog(LOG_ERR, 4898 "unable to start pool DNS %s: %m", 4899 pool->hostname); 4900 return; 4901 } 4902 4903 do { 4904 /* copy_addrinfo_list ai_addr points to a sockaddr_u */ 4905 rmtadr = (sockaddr_u *)(void *)pool->ai->ai_addr; 4906 pool->ai = pool->ai->ai_next; 4907 /* do not solicit when hopeless [Bug 3845] */ 4908 if ( (IS_IPV4(rmtadr) && !nonlocal_v4_addr_up) 4909 || (IS_IPV6(rmtadr) && !nonlocal_v6_addr_up)) { 4910 continue; 4911 } 4912 p = findexistingpeer(rmtadr, NULL, NULL, MODE_CLIENT, 0, NULL); 4913 } while (p != NULL && pool->ai != NULL); 4914 if (p != NULL) { 4915 return; /* out of addresses, re-query DNS next poll */ 4916 } 4917 restrict_source(rmtadr, FALSE, 1 + POOL_SOLICIT_WINDOW); 4918 lcladr = findinterface(rmtadr); 4919 memset(&xpkt, 0, sizeof(xpkt)); 4920 xpkt.li_vn_mode = PKT_LI_VN_MODE(sys_leap, pool->version, 4921 MODE_CLIENT); 4922 xpkt.stratum = STRATUM_TO_PKT(sys_stratum); 4923 xpkt.ppoll = pool->hpoll; 4924 xpkt.precision = sys_precision; 4925 xpkt.refid = sys_refid; 4926 xpkt.rootdelay = HTONS_FP(DTOFP(sys_rootdelay)); 4927 xpkt.rootdisp = HTONS_FP(DTOUFP(sys_rootdisp)); 4928 /* Bug 3596: What are the pros/cons of using sys_reftime here? */ 4929 HTONL_FP(&sys_reftime, &xpkt.reftime); 4930 4931 get_systime(&xmt_tx); 4932 pool->aorg = xmt_tx; 4933 4934 if (FLAG_LOOPNONCE & pool->flags) { 4935 l_fp nonce; 4936 4937 do { 4938 nonce.l_ui = ntp_random(); 4939 } while (0 == nonce.l_ui); 4940 do { 4941 nonce.l_uf = ntp_random(); 4942 } while (0 == nonce.l_uf); 4943 pool->nonce = nonce; 4944 HTONL_FP(&nonce, &xpkt.xmt); 4945 } else { 4946 L_CLR(&pool->nonce); 4947 HTONL_FP(&xmt_tx, &xpkt.xmt); 4948 } 4949 pool->sent++; 4950 pool->throttle += (1 << pool->minpoll) - 2; 4951 DPRINTF(1, ("pool_xmit: at %ld %s->%s pool\n", 4952 current_time, latoa(lcladr), stoa(rmtadr))); 4953 msyslog(LOG_INFO, "Soliciting pool server %s", stoa(rmtadr)); 4954 sendpkt(rmtadr, lcladr, 4955 sys_ttl[(pool->ttl >= sys_ttlmax) ? sys_ttlmax : pool->ttl], 4956 &xpkt, LEN_PKT_NOMAC); 4957 #endif /* WORKER */ 4958 } 4959 4960 4961 #ifdef AUTOKEY 4962 /* 4963 * group_test - test if this is the same group 4964 * 4965 * host assoc return action 4966 * none none 0 mobilize * 4967 * none group 0 mobilize * 4968 * group none 0 mobilize * 4969 * group group 1 mobilize 4970 * group different 1 ignore 4971 * * ignore if notrust 4972 */ 4973 int 4974 group_test( 4975 char *grp, 4976 char *ident 4977 ) 4978 { 4979 if (grp == NULL) 4980 return (0); 4981 4982 if (strcmp(grp, sys_groupname) == 0) 4983 return (0); 4984 4985 if (ident == NULL) 4986 return (1); 4987 4988 if (strcmp(grp, ident) == 0) 4989 return (0); 4990 4991 return (1); 4992 } 4993 #endif /* AUTOKEY */ 4994 4995 4996 #ifdef WORKER 4997 void 4998 pool_name_resolved( 4999 int rescode, 5000 int gai_errno, 5001 void * context, 5002 const char * name, 5003 const char * service, 5004 const struct addrinfo * hints, 5005 const struct addrinfo * res 5006 ) 5007 { 5008 struct peer * pool; /* pool solicitor association */ 5009 associd_t assoc; 5010 5011 if (rescode) { 5012 msyslog(LOG_ERR, 5013 "error resolving pool %s: %s (%d)", 5014 name, gai_strerror(rescode), rescode); 5015 return; 5016 } 5017 5018 assoc = (associd_t)(intptr_t)context; 5019 pool = findpeerbyassoc(assoc); 5020 if (NULL == pool) { 5021 msyslog(LOG_ERR, 5022 "Could not find assoc %u for pool DNS %s", 5023 assoc, name); 5024 return; 5025 } 5026 DPRINTF(1, ("pool DNS %s completed\n", name)); 5027 pool->addrs = copy_addrinfo_list(res); 5028 pool->ai = pool->addrs; 5029 pool_xmit(pool); 5030 5031 } 5032 #endif /* WORKER */ 5033 5034 5035 #ifdef AUTOKEY 5036 /* 5037 * key_expire - purge the key list 5038 */ 5039 void 5040 key_expire( 5041 struct peer *peer /* peer structure pointer */ 5042 ) 5043 { 5044 int i; 5045 5046 if (peer->keylist != NULL) { 5047 for (i = 0; i <= peer->keynumber; i++) 5048 authtrust(peer->keylist[i], 0); 5049 free(peer->keylist); 5050 peer->keylist = NULL; 5051 } 5052 value_free(&peer->sndval); 5053 peer->keynumber = 0; 5054 peer->flags &= ~FLAG_ASSOC; 5055 DPRINTF(1, ("key_expire: at %lu associd %d\n", current_time, 5056 peer->associd)); 5057 } 5058 #endif /* AUTOKEY */ 5059 5060 5061 /* 5062 * local_refid(peer) - Check peer refid to avoid selecting peers 5063 * currently synced to this ntpd. 5064 * Note that until 4.2.8p18 and 4.3.1XX ntpd calculated the IPv6 5065 * refid differently on different-endian systems. It now calculates 5066 * the refid the same on both, the same way it did on little-endian 5067 * in the past. On big-endian systems, ntpd also calculates a 5068 * byte-swapped version of each of its IPv6 local addresses' refids, 5069 * as endpt.old_refid and also detects a loop when seeing it. This 5070 * ensures new BE ntpd will detect loops interoperating with older 5071 * BE ntpd, and keeps the more-common LE old ntpd code detecting 5072 * loops with IPv6 refids correctly. Thanks to Hal Murray for 5073 * the byte-swapping idea. 5074 */ 5075 static int 5076 local_refid( 5077 struct peer * p 5078 ) 5079 { 5080 endpt * unicast_ep; 5081 5082 if (p->dstadr != NULL && !(INT_MCASTIF & p->dstadr->flags)) 5083 unicast_ep = p->dstadr; 5084 else 5085 unicast_ep = findinterface(&p->srcadr); 5086 5087 if (unicast_ep != NULL 5088 && ( p->refid == unicast_ep->addr_refid 5089 #ifdef WORDS_BIGENDIAN 5090 || ( IS_IPV6(&unicast_ep->sin) 5091 && p->refid == unicast_ep->old_refid) 5092 #endif 5093 )) { 5094 return TRUE; 5095 } else { 5096 return FALSE; 5097 } 5098 } 5099 5100 5101 /* 5102 * Determine if the peer is unfit for synchronization 5103 * 5104 * A peer is unfit for synchronization if 5105 * > TEST10 bad leap or stratum below floor or at or above ceiling 5106 * > TEST11 root distance exceeded for remote peer 5107 * > TEST12 a direct or indirect synchronization loop would form 5108 * > TEST13 unreachable or noselect 5109 */ 5110 int /* FALSE if fit, TRUE if unfit */ 5111 peer_unfit( 5112 struct peer *peer /* peer structure pointer */ 5113 ) 5114 { 5115 int rval = 0; 5116 5117 /* 5118 * A stratum error occurs if (1) the server has never been 5119 * synchronized, (2) the server stratum is below the floor or 5120 * greater than or equal to the ceiling. 5121 */ 5122 if ( peer->leap == LEAP_NOTINSYNC 5123 || peer->stratum < sys_floor 5124 || peer->stratum >= sys_ceiling) { 5125 rval |= TEST10; /* bad synch or stratum */ 5126 } 5127 5128 /* 5129 * A distance error for a remote peer occurs if the root 5130 * distance is greater than or equal to the distance threshold 5131 * plus the increment due to one host poll interval. 5132 */ 5133 if ( !(peer->flags & FLAG_REFCLOCK) 5134 && root_distance(peer) >= sys_maxdist 5135 + clock_phi * ULOGTOD(peer->hpoll)) { 5136 rval |= TEST11; /* distance exceeded */ 5137 } 5138 5139 /* 5140 * A loop error occurs if the remote peer is synchronized to the 5141 * local peer or if the remote peer is synchronized to the same 5142 * server as the local peer but only if the remote peer is 5143 * neither a reference clock nor an orphan. 5144 */ 5145 if (peer->stratum > 1 && local_refid(peer)) { 5146 rval |= TEST12; /* synchronization loop */ 5147 } 5148 5149 /* 5150 * An unreachable error occurs if the server is unreachable or 5151 * the noselect bit is set. 5152 */ 5153 if (!peer->reach || (peer->flags & FLAG_NOSELECT)) { 5154 rval |= TEST13; /* unreachable */ 5155 } 5156 5157 peer->flash &= ~PEER_TEST_MASK; 5158 peer->flash |= rval; 5159 return (rval); 5160 } 5161 5162 5163 /* 5164 * Find the precision of this particular machine 5165 */ 5166 #define MINSTEP 20e-9 /* minimum clock increment (s) */ 5167 #define MAXSTEP 1 /* maximum clock increment (s) */ 5168 #define MINCHANGES 12 /* minimum number of step samples */ 5169 #define MAXLOOPS ((int)(1. / MINSTEP)) /* avoid infinite loop */ 5170 5171 /* 5172 * This routine measures the system precision defined as the minimum of 5173 * a sequence of differences between successive readings of the system 5174 * clock. However, if a difference is less than MINSTEP, the clock has 5175 * been read more than once during a clock tick and the difference is 5176 * ignored. We set MINSTEP greater than zero in case something happens 5177 * like a cache miss, and to tolerate underlying system clocks which 5178 * ensure each reading is strictly greater than prior readings while 5179 * using an underlying stepping (not interpolated) clock. 5180 * 5181 * sys_tick and sys_precision represent the time to read the clock for 5182 * systems with high-precision clocks, and the tick interval or step 5183 * size for lower-precision stepping clocks. 5184 * 5185 * This routine also measures the time to read the clock on stepping 5186 * system clocks by counting the number of readings between changes of 5187 * the underlying clock. With either type of clock, the minimum time 5188 * to read the clock is saved as sys_fuzz, and used to ensure the 5189 * get_systime() readings always increase and are fuzzed below sys_fuzz. 5190 */ 5191 void 5192 measure_precision(void) 5193 { 5194 /* 5195 * With sys_fuzz set to zero, get_systime() fuzzing of low bits 5196 * is effectively disabled. trunc_os_clock is FALSE to disable 5197 * get_ostime() simulation of a low-precision system clock. 5198 */ 5199 set_sys_fuzz(0.); 5200 trunc_os_clock = FALSE; 5201 measured_tick = measure_tick_fuzz(); 5202 set_sys_tick_precision(measured_tick); 5203 msyslog(LOG_INFO, "proto: precision = %.3f usec (%d)", 5204 sys_tick * 1e6, sys_precision); 5205 if (sys_fuzz < sys_tick) { 5206 msyslog(LOG_NOTICE, "proto: fuzz beneath %.3f usec", 5207 sys_fuzz * 1e6); 5208 } 5209 } 5210 5211 5212 /* 5213 * measure_tick_fuzz() 5214 * 5215 * measures the minimum time to read the clock (stored in sys_fuzz) 5216 * and returns the tick, the larger of the minimum increment observed 5217 * between successive clock readings and the time to read the clock. 5218 */ 5219 double 5220 measure_tick_fuzz(void) 5221 { 5222 l_fp minstep; /* MINSTEP as l_fp */ 5223 l_fp val; /* current seconds fraction */ 5224 l_fp last; /* last seconds fraction */ 5225 l_fp ldiff; /* val - last */ 5226 double tick; /* computed tick value */ 5227 double diff; 5228 long repeats; 5229 long max_repeats; 5230 int changes; 5231 int i; /* log2 precision */ 5232 5233 tick = MAXSTEP; 5234 max_repeats = 0; 5235 repeats = 0; 5236 changes = 0; 5237 DTOLFP(MINSTEP, &minstep); 5238 get_systime(&last); 5239 for (i = 0; i < MAXLOOPS && changes < MINCHANGES; i++) { 5240 get_systime(&val); 5241 ldiff = val; 5242 L_SUB(&ldiff, &last); 5243 last = val; 5244 if (L_ISGT(&ldiff, &minstep)) { 5245 max_repeats = max(repeats, max_repeats); 5246 repeats = 0; 5247 changes++; 5248 LFPTOD(&ldiff, diff); 5249 tick = min(diff, tick); 5250 } else { 5251 repeats++; 5252 } 5253 } 5254 if (changes < MINCHANGES) { 5255 msyslog(LOG_ERR, "Fatal error: precision could not be measured (MINSTEP too large?)"); 5256 exit(1); 5257 } 5258 5259 if (0 == max_repeats) { 5260 set_sys_fuzz(tick); 5261 } else { 5262 set_sys_fuzz(tick / max_repeats); 5263 } 5264 5265 return tick; 5266 } 5267 5268 5269 void 5270 set_sys_tick_precision( 5271 double tick 5272 ) 5273 { 5274 int i; 5275 5276 if (tick > 1.) { 5277 msyslog(LOG_ERR, 5278 "unsupported tick %.3f > 1s ignored", tick); 5279 return; 5280 } 5281 if (tick < measured_tick) { 5282 msyslog(LOG_ERR, 5283 "proto: tick %.3f less than measured tick %.3f, ignored", 5284 tick, measured_tick); 5285 return; 5286 } else if (tick > measured_tick) { 5287 trunc_os_clock = TRUE; 5288 msyslog(LOG_NOTICE, 5289 "proto: truncating system clock to multiples of %.9f", 5290 tick); 5291 } 5292 sys_tick = tick; 5293 5294 /* 5295 * Find the nearest power of two. 5296 */ 5297 for (i = 0; tick <= 1; i--) 5298 tick *= 2; 5299 if (tick - 1 > 1 - tick / 2) 5300 i++; 5301 5302 sys_precision = (s_char)i; 5303 } 5304 5305 5306 /* 5307 * init_proto - initialize the protocol module's data 5308 */ 5309 void 5310 init_proto(void) 5311 { 5312 l_fp dummy; 5313 int i; 5314 5315 /* 5316 * Fill in the sys_* stuff. Default is don't listen to 5317 * broadcasting, require authentication. 5318 */ 5319 set_sys_leap(LEAP_NOTINSYNC); 5320 sys_stratum = STRATUM_UNSPEC; 5321 memcpy(&sys_refid, "INIT", 4); 5322 sys_peer = NULL; 5323 sys_rootdelay = 0; 5324 sys_rootdisp = 0; 5325 L_CLR(&sys_reftime); 5326 sys_jitter = 0; 5327 measure_precision(); 5328 get_systime(&dummy); 5329 sys_survivors = 0; 5330 sys_manycastserver = 0; 5331 sys_bclient = 0; 5332 sys_mclient = 0; 5333 sys_bdelay = BDELAY_DEFAULT; /*[Bug 3031] delay cutoff */ 5334 sys_authenticate = 1; 5335 sys_stattime = current_time; 5336 orphwait = current_time + sys_orphwait; 5337 proto_clr_stats(); 5338 for (i = 0; i < MAX_TTL; ++i) 5339 sys_ttl[i] = (u_char)((i * 256) / MAX_TTL); 5340 sys_ttlmax = (MAX_TTL - 1); 5341 hardpps_enable = 0; 5342 stats_control = 1; 5343 } 5344 5345 5346 /* 5347 * proto_config - configure the protocol module 5348 */ 5349 void 5350 proto_config( 5351 int item, 5352 u_long value, 5353 double dvalue, 5354 sockaddr_u *svalue 5355 ) 5356 { 5357 /* 5358 * Figure out what he wants to change, then do it 5359 */ 5360 DPRINTF(2, ("proto_config: code %d value %lu dvalue %lf\n", 5361 item, value, dvalue)); 5362 5363 switch (item) { 5364 5365 /* 5366 * enable and disable commands - arguments are Boolean. 5367 */ 5368 case PROTO_AUTHENTICATE: /* authentication (auth) */ 5369 sys_authenticate = value; 5370 break; 5371 5372 case PROTO_BROADCLIENT: /* broadcast client (bclient) */ 5373 sys_bclient = (int)value; 5374 if (!sys_bclient) 5375 io_unsetbclient(); 5376 else 5377 io_setbclient(); 5378 break; 5379 5380 #ifdef REFCLOCK 5381 case PROTO_CAL: /* refclock calibrate (calibrate) */ 5382 cal_enable = value; 5383 break; 5384 #endif /* REFCLOCK */ 5385 5386 case PROTO_KERNEL: /* kernel discipline (kernel) */ 5387 select_loop(value); 5388 break; 5389 5390 case PROTO_MONITOR: /* monitoring (monitor) */ 5391 if (value) 5392 mon_start(MON_ON); 5393 else { 5394 mon_stop(MON_ON); 5395 if (mon_enabled) 5396 msyslog(LOG_WARNING, 5397 "restrict: 'monitor' cannot be disabled while 'limited' is enabled"); 5398 } 5399 break; 5400 5401 case PROTO_NTP: /* NTP discipline (ntp) */ 5402 ntp_enable = value; 5403 break; 5404 5405 case PROTO_MODE7: /* mode7 management (ntpdc) */ 5406 ntp_mode7 = value; 5407 break; 5408 5409 case PROTO_PPS: /* PPS discipline (pps) */ 5410 hardpps_enable = value; 5411 break; 5412 5413 case PROTO_FILEGEN: /* statistics (stats) */ 5414 stats_control = value; 5415 break; 5416 5417 /* 5418 * tos command - arguments are double, sometimes cast to int 5419 */ 5420 5421 case PROTO_BCPOLLBSTEP: /* Broadcast Poll Backstep gate (bcpollbstep) */ 5422 sys_bcpollbstep = (u_char)dvalue; 5423 break; 5424 5425 case PROTO_BEACON: /* manycast beacon (beacon) */ 5426 sys_beacon = (int)dvalue; 5427 break; 5428 5429 case PROTO_BROADDELAY: /* default broadcast delay (bdelay) */ 5430 sys_bdelay = (dvalue ? dvalue : BDELAY_DEFAULT); 5431 break; 5432 5433 case PROTO_CEILING: /* stratum ceiling (ceiling) */ 5434 sys_ceiling = (int)dvalue; 5435 break; 5436 5437 case PROTO_COHORT: /* cohort switch (cohort) */ 5438 sys_cohort = (int)dvalue; 5439 break; 5440 5441 case PROTO_FLOOR: /* stratum floor (floor) */ 5442 sys_floor = (int)dvalue; 5443 break; 5444 5445 case PROTO_MAXCLOCK: /* maximum candidates (maxclock) */ 5446 sys_maxclock = (int)dvalue; 5447 break; 5448 5449 case PROTO_MAXDIST: /* select threshold (maxdist) */ 5450 sys_maxdist = dvalue; 5451 break; 5452 5453 case PROTO_CALLDELAY: /* modem call delay (mdelay) */ 5454 break; /* NOT USED */ 5455 5456 case PROTO_MINCLOCK: /* minimum candidates (minclock) */ 5457 sys_minclock = (int)dvalue; 5458 break; 5459 5460 case PROTO_MINDISP: /* minimum distance (mindist) */ 5461 sys_mindisp = dvalue; 5462 break; 5463 5464 case PROTO_MINSANE: /* minimum survivors (minsane) */ 5465 sys_minsane = (int)dvalue; 5466 break; 5467 5468 case PROTO_ORPHAN: /* orphan stratum (orphan) */ 5469 sys_orphan = (int)dvalue; 5470 break; 5471 5472 case PROTO_ORPHWAIT: /* orphan wait (orphwait) */ 5473 orphwait -= sys_orphwait; 5474 sys_orphwait = (dvalue >= 1) ? (int)dvalue : NTP_ORPHWAIT; 5475 orphwait += sys_orphwait; 5476 break; 5477 5478 /* 5479 * Miscellaneous commands 5480 */ 5481 case PROTO_MULTICAST_ADD: /* add group address */ 5482 if (svalue != NULL) 5483 io_multicast_add(svalue); 5484 sys_mclient = 1; 5485 break; 5486 5487 case PROTO_MULTICAST_DEL: /* delete group address */ 5488 if (svalue != NULL) 5489 io_multicast_del(svalue); 5490 break; 5491 5492 /* 5493 * Peer_clear Early policy choices 5494 */ 5495 5496 case PROTO_PCEDIGEST: /* Digest */ 5497 peer_clear_digest_early = value; 5498 break; 5499 5500 /* 5501 * Unpeer Early policy choices 5502 */ 5503 5504 case PROTO_UECRYPTO: /* Crypto */ 5505 unpeer_crypto_early = value; 5506 break; 5507 5508 case PROTO_UECRYPTONAK: /* Crypto_NAK */ 5509 unpeer_crypto_nak_early = value; 5510 break; 5511 5512 case PROTO_UEDIGEST: /* Digest */ 5513 unpeer_digest_early = value; 5514 break; 5515 5516 default: 5517 msyslog(LOG_NOTICE, 5518 "proto: unsupported option %d", item); 5519 } 5520 } 5521 5522 5523 /* 5524 * proto_clr_stats - clear protocol stat counters 5525 */ 5526 void 5527 proto_clr_stats(void) 5528 { 5529 sys_stattime = current_time; 5530 sys_received = 0; 5531 sys_processed = 0; 5532 sys_newversion = 0; 5533 sys_oldversion = 0; 5534 sys_declined = 0; 5535 sys_restricted = 0; 5536 sys_badlength = 0; 5537 sys_badauth = 0; 5538 sys_limitrejected = 0; 5539 sys_kodsent = 0; 5540 sys_lamport = 0; 5541 sys_tsrounding = 0; 5542 } 5543
Indexes created Fri Oct 02 00:25:19 UTC 2026