1/* $NetBSD: ntp_leapsec.c,v 1.7 2020/05/25 20:47:25 christos Exp $ */ 2 3/* 4 * ntp_leapsec.c - leap second processing for NTPD 5 * 6 * Written by Juergen Perlinger (perlinger@ntp.org) for the NTP project. 7 * The contents of 'html/copyright.html' apply. 8 * ---------------------------------------------------------------------- 9 * This is an attempt to get the leap second handling into a dedicated 10 * module to make the somewhat convoluted logic testable. 11 */ 12 13#include <config.h> 14#include <sys/types.h> 15#include <sys/stat.h> 16#include <ctype.h> 17 18#include "ntp_types.h" 19#include "ntp_fp.h" 20#include "ntp_stdlib.h" 21#include "ntp_calendar.h" 22#include "ntp_leapsec.h" 23#include "ntp.h" 24#include "vint64ops.h" 25#include "lib_strbuf.h" 26 27#include "isc/sha1.h" 28 29static const char * const logPrefix = "leapsecond file"; 30 31/* --------------------------------------------------------------------- 32 * GCC is rather sticky with its 'const' attribute. We have to do it more 33 * explicit than with a cast if we want to get rid of a CONST qualifier. 34 * Greetings from the PASCAL world, where casting was only possible via 35 * untagged unions... 36 */ 37static inline void* 38noconst( 39 const void* ptr 40 ) 41{ 42 union { 43 const void * cp; 44 void * vp; 45 } tmp; 46 tmp.cp = ptr; 47 return tmp.vp; 48} 49 50/* --------------------------------------------------------------------- 51 * Our internal data structure 52 */ 53#define MAX_HIST 10 /* history of leap seconds */ 54 55struct leap_info { 56 vint64 ttime; /* transition time (after the step, ntp scale) */ 57 uint32_t stime; /* schedule limit (a month before transition) */ 58 int16_t taiof; /* TAI offset on and after the transition */ 59 uint8_t dynls; /* dynamic: inserted on peer/clock request */ 60}; 61typedef struct leap_info leap_info_t; 62 63struct leap_head { 64 vint64 update; /* time of information update */ 65 vint64 expire; /* table expiration time */ 66 uint16_t size; /* number of infos in table */ 67 int16_t base_tai; /* total leaps before first entry */ 68 int16_t this_tai; /* current TAI offset */ 69 int16_t next_tai; /* TAI offset after 'when' */ 70 vint64 dtime; /* due time (current era end) */ 71 vint64 ttime; /* nominal transition time (next era start) */ 72 vint64 stime; /* schedule time (when we take notice) */ 73 vint64 ebase; /* base time of this leap era */ 74 uint8_t dynls; /* next leap is dynamic (by peer request) */ 75}; 76typedef struct leap_head leap_head_t; 77 78struct leap_table { 79 leap_signature_t lsig; 80 leap_head_t head; 81 leap_info_t info[MAX_HIST]; 82}; 83 84/* Where we store our tables */ 85static leap_table_t _ltab[2], *_lptr; 86static int/*BOOL*/ _electric; 87 88/* Forward decls of local helpers */ 89static int add_range(leap_table_t*, const leap_info_t*); 90static char * get_line(leapsec_reader, void*, char*, size_t); 91static char * skipws(const char*); 92static int parsefail(const char * cp, const char * ep); 93static void reload_limits(leap_table_t*, const vint64*); 94static void fetch_leap_era(leap_era_t*, const leap_table_t*, 95 const vint64*); 96static int betweenu32(uint32_t, uint32_t, uint32_t); 97static void reset_times(leap_table_t*); 98static int leapsec_add(leap_table_t*, const vint64*, int); 99static int leapsec_raw(leap_table_t*, const vint64 *, int, int); 100static const char * lstostr(const vint64 * ts); 101 102/* ===================================================================== 103 * Get & Set the current leap table 104 */ 105 106/* ------------------------------------------------------------------ */ 107leap_table_t * 108leapsec_get_table( 109 int alternate) 110{ 111 leap_table_t *p1, *p2; 112 113 p1 = _lptr; 114 if (p1 == &_ltab[0]) { 115 p2 = &_ltab[1]; 116 } else if (p1 == &_ltab[1]) { 117 p2 = &_ltab[0]; 118 } else { 119 p1 = &_ltab[0]; 120 p2 = &_ltab[1]; 121 reset_times(p1); 122 reset_times(p2); 123 _lptr = p1; 124 } 125 if (alternate) { 126 memcpy(p2, p1, sizeof(leap_table_t)); 127 p1 = p2; 128 } 129 130 return p1; 131} 132 133/* ------------------------------------------------------------------ */ 134int/*BOOL*/ 135leapsec_set_table( 136 leap_table_t * pt) 137{ 138 if (pt == &_ltab[0] || pt == &_ltab[1]) 139 _lptr = pt; 140 return _lptr == pt; 141} 142 143/* ------------------------------------------------------------------ */ 144int/*BOOL*/ 145leapsec_electric( 146 int/*BOOL*/ on) 147{ 148 int res = _electric; 149 if (on < 0) 150 return res; 151 152 _electric = (on != 0); 153 if (_electric == res) 154 return res; 155 156 if (_lptr == &_ltab[0] || _lptr == &_ltab[1]) 157 reset_times(_lptr); 158 159 return res; 160} 161 162/* ===================================================================== 163 * API functions that operate on tables 164 */ 165 166/* --------------------------------------------------------------------- 167 * Clear all leap second data. Use it for init & cleanup 168 */ 169void 170leapsec_clear( 171 leap_table_t * pt) 172{ 173 memset(&pt->lsig, 0, sizeof(pt->lsig)); 174 memset(&pt->head, 0, sizeof(pt->head)); 175 reset_times(pt); 176} 177 178/* --------------------------------------------------------------------- 179 * Load a leap second file and check expiration on the go 180 */ 181int/*BOOL*/ 182leapsec_load( 183 leap_table_t * pt , 184 leapsec_reader func, 185 void * farg, 186 int use_build_limit) 187{ 188 char *cp, *ep, linebuf[50]; 189 vint64 ttime, limit; 190 long taiof; 191 struct calendar build; 192 193 leapsec_clear(pt); 194 if (use_build_limit && ntpcal_get_build_date(&build)) { 195 /* don't prune everything -- permit the last 10yrs 196 * before build. 197 */ 198 build.year -= 10; 199 limit = ntpcal_date_to_ntp64(&build); 200 } else { 201 memset(&limit, 0, sizeof(limit)); 202 } 203 204 while (get_line(func, farg, linebuf, sizeof(linebuf))) { 205 cp = linebuf; 206 if (*cp == '#') { 207 cp++; 208 if (*cp == '@') { 209 cp = skipws(cp+1); 210 pt->head.expire = strtouv64(cp, &ep, 10); 211 if (parsefail(cp, ep)) 212 goto fail_read; 213 pt->lsig.etime = pt->head.expire.D_s.lo; 214 } else if (*cp == '$') { 215 cp = skipws(cp+1); 216 pt->head.update = strtouv64(cp, &ep, 10); 217 if (parsefail(cp, ep)) 218 goto fail_read; 219 } 220 } else if (isdigit((u_char)*cp)) { 221 ttime = strtouv64(cp, &ep, 10); 222 if (parsefail(cp, ep)) 223 goto fail_read; 224 cp = skipws(ep); 225 taiof = strtol(cp, &ep, 10); 226 if ( parsefail(cp, ep) 227 || taiof > SHRT_MAX || taiof < SHRT_MIN) 228 goto fail_read; 229 if (ucmpv64(&ttime, &limit) >= 0) { 230 if (!leapsec_raw(pt, &ttime, 231 taiof, FALSE)) 232 goto fail_insn; 233 } else { 234 pt->head.base_tai = (int16_t)taiof; 235 } 236 pt->lsig.ttime = ttime.D_s.lo; 237 pt->lsig.taiof = (int16_t)taiof; 238 } 239 } 240 return TRUE; 241 242fail_read: 243 errno = EILSEQ; 244fail_insn: 245 leapsec_clear(pt); 246 return FALSE; 247} 248 249/* --------------------------------------------------------------------- 250 * Dump a table in human-readable format. Use 'fprintf' and a FILE 251 * pointer if you want to get it printed into a stream. 252 */ 253void 254leapsec_dump( 255 const leap_table_t * pt , 256 leapsec_dumper func, 257 void * farg) 258{ 259 int idx; 260 vint64 ts; 261 struct calendar atb, ttb; 262 263 ntpcal_ntp64_to_date(&ttb, &pt->head.expire); 264 (*func)(farg, "leap table (%u entries) expires at %04u-%02u-%02u:\n", 265 pt->head.size, 266 ttb.year, ttb.month, ttb.monthday); 267 idx = pt->head.size; 268 while (idx-- != 0) { 269 ts = pt->info[idx].ttime; 270 ntpcal_ntp64_to_date(&ttb, &ts); 271 ts = subv64u32(&ts, pt->info[idx].stime); 272 ntpcal_ntp64_to_date(&atb, &ts); 273 274 (*func)(farg, "%04u-%02u-%02u [%c] (%04u-%02u-%02u) - %d\n", 275 ttb.year, ttb.month, ttb.monthday, 276 "-*"[pt->info[idx].dynls != 0], 277 atb.year, atb.month, atb.monthday, 278 pt->info[idx].taiof); 279 } 280} 281 282/* ===================================================================== 283 * usecase driven API functions 284 */ 285 286int/*BOOL*/ 287leapsec_query( 288 leap_result_t * qr , 289 uint32_t ts32 , 290 const time_t * pivot) 291{ 292 leap_table_t * pt; 293 vint64 ts64, last, next; 294 uint32_t due32; 295 int fired; 296 297 /* preset things we use later on... */ 298 fired = FALSE; 299 ts64 = ntpcal_ntp_to_ntp(ts32, pivot); 300 pt = leapsec_get_table(FALSE); 301 memset(qr, 0, sizeof(leap_result_t)); 302 303 if (ucmpv64(&ts64, &pt->head.ebase) < 0) { 304 /* Most likely after leap frame reset. Could also be a 305 * backstep of the system clock. Anyway, get the new 306 * leap era frame. 307 */ 308 reload_limits(pt, &ts64); 309 } else if (ucmpv64(&ts64, &pt->head.dtime) >= 0) { 310 /* Boundary crossed in forward direction. This might 311 * indicate a leap transition, so we prepare for that 312 * case. 313 * 314 * Some operations below are actually NOPs in electric 315 * mode, but having only one code path that works for 316 * both modes is easier to maintain. 317 * 318 * There's another quirk we must keep looking out for: 319 * If we just stepped the clock, the step might have 320 * crossed a leap boundary. As with backward steps, we 321 * do not want to raise the 'fired' event in that case. 322 * So we raise the 'fired' event only if we're close to 323 * the transition and just reload the limits otherwise. 324 */ 325 last = addv64i32(&pt->head.dtime, 3); /* get boundary */ 326 if (ucmpv64(&ts64, &last) >= 0) { 327 /* that was likely a query after a step */ 328 reload_limits(pt, &ts64); 329 } else { 330 /* close enough for deeper examination */ 331 last = pt->head.ttime; 332 qr->warped = (int16_t)(last.D_s.lo - 333 pt->head.dtime.D_s.lo); 334 next = addv64i32(&ts64, qr->warped); 335 reload_limits(pt, &next); 336 fired = ucmpv64(&pt->head.ebase, &last) == 0; 337 if (fired) { 338 ts64 = next; 339 ts32 = next.D_s.lo; 340 } else { 341 qr->warped = 0; 342 } 343 } 344 } 345 346 qr->tai_offs = pt->head.this_tai; 347 qr->ebase = pt->head.ebase; 348 qr->ttime = pt->head.ttime; 349 350 /* If before the next scheduling alert, we're done. */ 351 if (ucmpv64(&ts64, &pt->head.stime) < 0) 352 return fired; 353 354 /* now start to collect the remaining data */ 355 due32 = pt->head.dtime.D_s.lo; 356 357 qr->tai_diff = pt->head.next_tai - pt->head.this_tai; 358 qr->ddist = due32 - ts32; 359 qr->dynamic = pt->head.dynls; 360 qr->proximity = LSPROX_SCHEDULE; 361 362 /* if not in the last day before transition, we're done. */ 363 if (!betweenu32(due32 - SECSPERDAY, ts32, due32)) 364 return fired; 365 366 qr->proximity = LSPROX_ANNOUNCE; 367 if (!betweenu32(due32 - 10, ts32, due32)) 368 return fired; 369 370 /* The last 10s before the transition. Prepare for action! */ 371 qr->proximity = LSPROX_ALERT; 372 return fired; 373} 374 375/* ------------------------------------------------------------------ */ 376int/*BOOL*/ 377leapsec_query_era( 378 leap_era_t * qr , 379 uint32_t ntpts, 380 const time_t * pivot) 381{ 382 const leap_table_t * pt; 383 vint64 ts64; 384 385 pt = leapsec_get_table(FALSE); 386 ts64 = ntpcal_ntp_to_ntp(ntpts, pivot); 387 fetch_leap_era(qr, pt, &ts64); 388 return TRUE; 389} 390 391/* ------------------------------------------------------------------ */ 392int/*BOOL*/ 393leapsec_frame( 394 leap_result_t *qr) 395{ 396 const leap_table_t * pt; 397 398 memset(qr, 0, sizeof(leap_result_t)); 399 pt = leapsec_get_table(FALSE); 400 401 qr->tai_offs = pt->head.this_tai; 402 qr->tai_diff = pt->head.next_tai - pt->head.this_tai; 403 qr->ebase = pt->head.ebase; 404 qr->ttime = pt->head.ttime; 405 qr->dynamic = pt->head.dynls; 406 407 return ucmpv64(&pt->head.ttime, &pt->head.stime) >= 0; 408} 409 410/* ------------------------------------------------------------------ */ 411/* Reset the current leap frame */ 412void 413leapsec_reset_frame(void) 414{ 415 reset_times(leapsec_get_table(FALSE)); 416} 417 418/* ------------------------------------------------------------------ */ 419/* load a file from a FILE pointer. Note: If hcheck is true, load 420 * only after successful signature check. The stream must be seekable 421 * or this will fail. 422 */ 423int/*BOOL*/ 424leapsec_load_stream( 425 FILE * ifp , 426 const char * fname, 427 int/*BOOL*/ logall, 428 int/*BOOL*/ vhash) 429{ 430 leap_table_t *pt; 431 int rcheck; 432 433 if (NULL == fname) 434 fname = "<unknown>"; 435 436 if (vhash) { 437 rcheck = leapsec_validate((leapsec_reader)getc, ifp); 438 if (logall) 439 switch (rcheck) 440 { 441 case LSVALID_GOODHASH: 442 msyslog(LOG_NOTICE, "%s ('%s'): good hash signature", 443 logPrefix, fname); 444 break; 445 446 case LSVALID_NOHASH: 447 msyslog(LOG_ERR, "%s ('%s'): no hash signature", 448 logPrefix, fname); 449 break; 450 case LSVALID_BADHASH: 451 msyslog(LOG_ERR, "%s ('%s'): signature mismatch", 452 logPrefix, fname); 453 break; 454 case LSVALID_BADFORMAT: 455 msyslog(LOG_ERR, "%s ('%s'): malformed hash signature", 456 logPrefix, fname); 457 break; 458 default: 459 msyslog(LOG_ERR, "%s ('%s'): unknown error code %d", 460 logPrefix, fname, rcheck); 461 break; 462 } 463 if (rcheck < 0) 464 return FALSE; 465 rewind(ifp); 466 } 467 pt = leapsec_get_table(TRUE); 468 if (!leapsec_load(pt, (leapsec_reader)getc, ifp, TRUE)) { 469 switch (errno) { 470 case EINVAL: 471 msyslog(LOG_ERR, "%s ('%s'): bad transition time", 472 logPrefix, fname); 473 break; 474 case ERANGE: 475 msyslog(LOG_ERR, "%s ('%s'): times not ascending", 476 logPrefix, fname); 477 break; 478 default: 479 msyslog(LOG_ERR, "%s ('%s'): parsing error", 480 logPrefix, fname); 481 break; 482 } 483 return FALSE; 484 } 485 486 if (pt->head.size) 487 msyslog(LOG_NOTICE, "%s ('%s'): loaded, expire=%s last=%s ofs=%d", 488 logPrefix, fname, lstostr(&pt->head.expire), 489 lstostr(&pt->info[0].ttime), pt->info[0].taiof); 490 else 491 msyslog(LOG_NOTICE, 492 "%s ('%s'): loaded, expire=%s ofs=%d (no entries after build date)", 493 logPrefix, fname, lstostr(&pt->head.expire), 494 pt->head.base_tai); 495 496 return leapsec_set_table(pt); 497} 498 499/* ------------------------------------------------------------------ */ 500int/*BOOL*/ 501leapsec_load_file( 502 const char * fname, 503 struct stat * sb_old, 504 int/*BOOL*/ force, 505 int/*BOOL*/ logall, 506 int/*BOOL*/ vhash) 507{ 508 FILE * fp; 509 struct stat sb_new; 510 int rc; 511 512 /* just do nothing if there is no leap file */ 513 if ( !(fname && *fname) ) 514 return FALSE; 515 516 /* try to stat the leapfile */ 517 if (0 != stat(fname, &sb_new)) { 518 if (logall) 519 msyslog(LOG_ERR, "%s ('%s'): stat failed: %m", 520 logPrefix, fname); 521 return FALSE; 522 } 523 524 /* silently skip to postcheck if no new file found */ 525 if (NULL != sb_old) { 526 if (!force 527 && sb_old->st_mtime == sb_new.st_mtime 528 && sb_old->st_ctime == sb_new.st_ctime 529 ) 530 return FALSE; 531 *sb_old = sb_new; 532 } 533 534 /* try to open the leap file, complain if that fails 535 * 536 * [perlinger@ntp.org] 537 * coverity raises a TOCTOU (time-of-check/time-of-use) issue 538 * here, which is not entirely helpful: While there is indeed a 539 * possible race condition between the 'stat()' call above and 540 * the 'fopen)' call below, I intentionally want to omit the 541 * overhead of opening the file and calling 'fstat()', because 542 * in most cases the file would have be to closed anyway without 543 * reading the contents. I chose to disable the coverity 544 * warning instead. 545 * 546 * So unless someone comes up with a reasonable argument why 547 * this could be a real issue, I'll just try to silence coverity 548 * on that topic. 549 */ 550 /* coverity[toctou] */ 551 if ((fp = fopen(fname, "r")) == NULL) { 552 if (logall) 553 msyslog(LOG_ERR, 554 "%s ('%s'): open failed: %m", 555 logPrefix, fname); 556 return FALSE; 557 } 558 559 rc = leapsec_load_stream(fp, fname, logall, vhash); 560 fclose(fp); 561 return rc; 562} 563 564/* ------------------------------------------------------------------ */ 565void 566leapsec_getsig( 567 leap_signature_t * psig) 568{ 569 const leap_table_t * pt; 570 571 pt = leapsec_get_table(FALSE); 572 memcpy(psig, &pt->lsig, sizeof(leap_signature_t)); 573} 574 575/* ------------------------------------------------------------------ */ 576int/*BOOL*/ 577leapsec_expired( 578 uint32_t when, 579 const time_t * tpiv) 580{ 581 const leap_table_t * pt; 582 vint64 limit; 583 584 pt = leapsec_get_table(FALSE); 585 limit = ntpcal_ntp_to_ntp(when, tpiv); 586 return ucmpv64(&limit, &pt->head.expire) >= 0; 587} 588 589/* ------------------------------------------------------------------ */ 590int32_t 591leapsec_daystolive( 592 uint32_t when, 593 const time_t * tpiv) 594{ 595 const leap_table_t * pt; 596 vint64 limit; 597 598 pt = leapsec_get_table(FALSE); 599 limit = ntpcal_ntp_to_ntp(when, tpiv); 600 limit = subv64(&pt->head.expire, &limit); 601 return ntpcal_daysplit(&limit).hi; 602} 603 604/* ------------------------------------------------------------------ */ 605#if 0 /* currently unused -- possibly revived later */ 606int/*BOOL*/ 607leapsec_add_fix( 608 int total, 609 uint32_t ttime, 610 uint32_t etime, 611 const time_t * pivot) 612{ 613 time_t tpiv; 614 leap_table_t * pt; 615 vint64 tt64, et64; 616 617 if (pivot == NULL) { 618 time(&tpiv); 619 pivot = &tpiv; 620 } 621 622 et64 = ntpcal_ntp_to_ntp(etime, pivot); 623 tt64 = ntpcal_ntp_to_ntp(ttime, pivot); 624 pt = leapsec_get_table(TRUE); 625 626 if ( ucmpv64(&et64, &pt->head.expire) <= 0 627 || !leapsec_raw(pt, &tt64, total, FALSE) ) 628 return FALSE; 629 630 pt->lsig.etime = etime; 631 pt->lsig.ttime = ttime; 632 pt->lsig.taiof = (int16_t)total; 633 634 pt->head.expire = et64; 635 636 return leapsec_set_table(pt); 637} 638#endif 639 640/* ------------------------------------------------------------------ */ 641int/*BOOL*/ 642leapsec_add_dyn( 643 int insert, 644 uint32_t ntpnow, 645 const time_t * pivot ) 646{ 647 leap_table_t * pt; 648 vint64 now64; 649 650 pt = leapsec_get_table(TRUE); 651 now64 = ntpcal_ntp_to_ntp(ntpnow, pivot); 652 return ( leapsec_add(pt, &now64, (insert != 0)) 653 && leapsec_set_table(pt)); 654} 655 656/* ------------------------------------------------------------------ */ 657int/*BOOL*/ 658leapsec_autokey_tai( 659 int tai_offset, 660 uint32_t ntpnow , 661 const time_t * pivot ) 662{ 663 leap_table_t * pt; 664 leap_era_t era; 665 vint64 now64; 666 int idx; 667 668 (void)tai_offset; 669 pt = leapsec_get_table(FALSE); 670 671 /* Bail out if the basic offset is not zero and the putative 672 * offset is bigger than 10s. That was in 1972 -- we don't want 673 * to go back that far! 674 */ 675 if (pt->head.base_tai != 0 || tai_offset < 10) 676 return FALSE; 677 678 /* If there's already data in the table, check if an update is 679 * possible. Update is impossible if there are static entries 680 * (since this indicates a valid leapsecond file) or if we're 681 * too close to a leapsecond transition: We do not know on what 682 * side the transition the sender might have been, so we use a 683 * dead zone around the transition. 684 */ 685 686 /* Check for static entries */ 687 for (idx = 0; idx != pt->head.size; idx++) 688 if ( ! pt->info[idx].dynls) 689 return FALSE; 690 691 /* get the fulll time stamp and leap era for it */ 692 now64 = ntpcal_ntp_to_ntp(ntpnow, pivot); 693 fetch_leap_era(&era, pt, &now64); 694 695 /* check the limits with 20s dead band */ 696 era.ebase = addv64i32(&era.ebase, 20); 697 if (ucmpv64(&now64, &era.ebase) < 0) 698 return FALSE; 699 700 era.ttime = addv64i32(&era.ttime, -20); 701 if (ucmpv64(&now64, &era.ttime) > 0) 702 return FALSE; 703 704 /* Here we can proceed. Calculate the delta update. */ 705 tai_offset -= era.taiof; 706 707 /* Shift the header info offsets. */ 708 pt->head.base_tai += tai_offset; 709 pt->head.this_tai += tai_offset; 710 pt->head.next_tai += tai_offset; 711 712 /* Shift table entry offsets (if any) */ 713 for (idx = 0; idx != pt->head.size; idx++) 714 pt->info[idx].taiof += tai_offset; 715 716 /* claim success... */ 717 return TRUE; 718} 719 720 721/* ===================================================================== 722 * internal helpers 723 */ 724 725/* [internal] Reset / init the time window in the leap processor to 726 * force reload on next query. Since a leap transition cannot take place 727 * at an odd second, the value chosen avoids spurious leap transition 728 * triggers. Making all three times equal forces a reload. Using the 729 * maximum value for unsigned 64 bits makes finding the next leap frame 730 * a bit easier. 731 */ 732static void 733reset_times( 734 leap_table_t * pt) 735{ 736 memset(&pt->head.ebase, 0xFF, sizeof(vint64)); 737 pt->head.stime = pt->head.ebase; 738 pt->head.ttime = pt->head.ebase; 739 pt->head.dtime = pt->head.ebase; 740} 741 742/* [internal] Add raw data to the table, removing old entries on the 743 * fly. This cannot fail currently. 744 */ 745static int/*BOOL*/ 746add_range( 747 leap_table_t * pt, 748 const leap_info_t * pi) 749{ 750 /* If the table is full, make room by throwing out the oldest 751 * entry. But remember the accumulated leap seconds! 752 * 753 * Setting the first entry is a bit tricky, too: Simply assuming 754 * it is an insertion is wrong if the first entry is a dynamic 755 * leap second removal. So we decide on the sign -- if the first 756 * entry has a negative offset, we assume that it is a leap 757 * second removal. In both cases the table base offset is set 758 * accordingly to reflect the decision. 759 * 760 * In practice starting with a removal can only happen if the 761 * first entry is a dynamic request without having a leap file 762 * for the history proper. 763 */ 764 if (pt->head.size == 0) { 765 if (pi->taiof >= 0) 766 pt->head.base_tai = pi->taiof - 1; 767 else 768 pt->head.base_tai = pi->taiof + 1; 769 } else if (pt->head.size >= MAX_HIST) { 770 pt->head.size = MAX_HIST - 1; 771 pt->head.base_tai = pt->info[pt->head.size].taiof; 772 } 773 774 /* make room in lower end and insert item */ 775 memmove(pt->info+1, pt->info, pt->head.size*sizeof(*pt->info)); 776 pt->info[0] = *pi; 777 pt->head.size++; 778 779 /* invalidate the cached limit data -- we might have news ;-) 780 * 781 * This blocks a spurious transition detection. OTOH, if you add 782 * a value after the last query before a leap transition was 783 * expected to occur, this transition trigger is lost. But we 784 * can probably live with that. 785 */ 786 reset_times(pt); 787 return TRUE; 788} 789 790/* [internal] given a reader function, read characters into a buffer 791 * until either EOL or EOF is reached. Makes sure that the buffer is 792 * always NUL terminated, but silently truncates excessive data. The 793 * EOL-marker ('\n') is *not* stored in the buffer. 794 * 795 * Returns the pointer to the buffer, unless EOF was reached when trying 796 * to read the first character of a line. 797 */ 798static char * 799get_line( 800 leapsec_reader func, 801 void * farg, 802 char * buff, 803 size_t size) 804{ 805 int ch; 806 char *ptr; 807 808 /* if we cannot even store the delimiter, declare failure */ 809 if (buff == NULL || size == 0) 810 return NULL; 811 812 ptr = buff; 813 while (EOF != (ch = (*func)(farg)) && '\n' != ch) 814 if (size > 1) { 815 size--; 816 *ptr++ = (char)ch; 817 } 818 /* discard trailing whitespace */ 819 while (ptr != buff && isspace((u_char)ptr[-1])) 820 ptr--; 821 *ptr = '\0'; 822 return (ptr == buff && ch == EOF) ? NULL : buff; 823} 824 825/* [internal] skips whitespace characters from a character buffer. */ 826static char * 827skipws( 828 const char *ptr) 829{ 830 while (isspace((u_char)*ptr)) 831 ptr++; 832 return (char*)noconst(ptr); 833} 834 835/* [internal] check if a strtoXYZ ended at EOL or whitespace and 836 * converted something at all. Return TRUE if something went wrong. 837 */ 838static int/*BOOL*/ 839parsefail( 840 const char * cp, 841 const char * ep) 842{ 843 return (cp == ep) 844 || (*ep && *ep != '#' && !isspace((u_char)*ep)); 845} 846 847/* [internal] reload the table limits around the given time stamp. This 848 * is where the real work is done when it comes to table lookup and 849 * evaluation. Some care has been taken to have correct code for dealing 850 * with boundary conditions and empty tables. 851 * 852 * In electric mode, transition and trip time are the same. In dumb 853 * mode, the difference of the TAI offsets must be taken into account 854 * and trip time and transition time become different. The difference 855 * becomes the warping distance when the trip time is reached. 856 */ 857static void 858reload_limits( 859 leap_table_t * pt, 860 const vint64 * ts) 861{ 862 int idx; 863 864 /* Get full time and search the true lower bound. Use a 865 * simple loop here, since the number of entries does 866 * not warrant a binary search. This also works for an empty 867 * table, so there is no shortcut for that case. 868 */ 869 for (idx = 0; idx != pt->head.size; idx++) 870 if (ucmpv64(ts, &pt->info[idx].ttime) >= 0) 871 break; 872 873 /* get time limits with proper bound conditions. Note that the 874 * bounds of the table will be observed even if the table is 875 * empty -- no undefined condition must arise from this code. 876 */ 877 if (idx >= pt->head.size) { 878 memset(&pt->head.ebase, 0x00, sizeof(vint64)); 879 pt->head.this_tai = pt->head.base_tai; 880 } else { 881 pt->head.ebase = pt->info[idx].ttime; 882 pt->head.this_tai = pt->info[idx].taiof; 883 } 884 if (--idx >= 0) { 885 pt->head.next_tai = pt->info[idx].taiof; 886 pt->head.dynls = pt->info[idx].dynls; 887 pt->head.ttime = pt->info[idx].ttime; 888 889 if (_electric) 890 pt->head.dtime = pt->head.ttime; 891 else 892 pt->head.dtime = addv64i32( 893 &pt->head.ttime, 894 pt->head.next_tai - pt->head.this_tai); 895 896 pt->head.stime = subv64u32( 897 &pt->head.ttime, pt->info[idx].stime); 898 899 } else { 900 memset(&pt->head.ttime, 0xFF, sizeof(vint64)); 901 pt->head.stime = pt->head.ttime; 902 pt->head.dtime = pt->head.ttime; 903 pt->head.next_tai = pt->head.this_tai; 904 pt->head.dynls = 0; 905 } 906} 907 908/* [internal] fetch the leap era for a given time stamp. 909 * This is a cut-down version the algorithm used to reload the table 910 * limits, but it does not update any global state and provides just the 911 * era information for a given time stamp. 912 */ 913static void 914fetch_leap_era( 915 leap_era_t * into, 916 const leap_table_t * pt , 917 const vint64 * ts ) 918{ 919 int idx; 920 921 /* Simple search loop, also works with empty table. */ 922 for (idx = 0; idx != pt->head.size; idx++) 923 if (ucmpv64(ts, &pt->info[idx].ttime) >= 0) 924 break; 925 /* fetch era data, keeping an eye on boundary conditions */ 926 if (idx >= pt->head.size) { 927 memset(&into->ebase, 0x00, sizeof(vint64)); 928 into->taiof = pt->head.base_tai; 929 } else { 930 into->ebase = pt->info[idx].ttime; 931 into->taiof = pt->info[idx].taiof; 932 } 933 if (--idx >= 0) 934 into->ttime = pt->info[idx].ttime; 935 else 936 memset(&into->ttime, 0xFF, sizeof(vint64)); 937} 938 939/* [internal] Take a time stamp and create a leap second frame for 940 * it. This will schedule a leap second for the beginning of the next 941 * month, midnight UTC. The 'insert' argument tells if a leap second is 942 * added (!=0) or removed (==0). We do not handle multiple inserts 943 * (yet?) 944 * 945 * Returns 1 if the insert worked, 0 otherwise. (It's not possible to 946 * insert a leap second into the current history -- only appending 947 * towards the future is allowed!) 948 */ 949static int/*BOOL*/ 950leapsec_add( 951 leap_table_t* pt , 952 const vint64 * now64 , 953 int insert) 954{ 955 vint64 ttime, starttime; 956 struct calendar fts; 957 leap_info_t li; 958 959 /* Check against the table expiration and the latest available 960 * leap entry. Do not permit inserts, only appends, and only if 961 * the extend the table beyond the expiration! 962 */ 963 if ( ucmpv64(now64, &pt->head.expire) < 0 964 || (pt->head.size && ucmpv64(now64, &pt->info[0].ttime) <= 0)) { 965 errno = ERANGE; 966 return FALSE; 967 } 968 969 ntpcal_ntp64_to_date(&fts, now64); 970 /* To guard against dangling leap flags: do not accept leap 971 * second request on the 1st hour of the 1st day of the month. 972 */ 973 if (fts.monthday == 1 && fts.hour == 0) { 974 errno = EINVAL; 975 return FALSE; 976 } 977 978 /* Ok, do the remaining calculations */ 979 fts.monthday = 1; 980 fts.hour = 0; 981 fts.minute = 0; 982 fts.second = 0; 983 starttime = ntpcal_date_to_ntp64(&fts); 984 fts.month++; 985 ttime = ntpcal_date_to_ntp64(&fts); 986 987 li.ttime = ttime; 988 li.stime = ttime.D_s.lo - starttime.D_s.lo; 989 li.taiof = (pt->head.size ? pt->info[0].taiof : pt->head.base_tai) 990 + (insert ? 1 : -1); 991 li.dynls = 1; 992 return add_range(pt, &li); 993} 994 995/* [internal] Given a time stamp for a leap insertion (the exact begin 996 * of the new leap era), create new leap frame and put it into the 997 * table. This is the work horse for reading a leap file and getting a 998 * leap second update via authenticated network packet. 999 */ 1000int/*BOOL*/ 1001leapsec_raw( 1002 leap_table_t * pt, 1003 const vint64 * ttime, 1004 int taiof, 1005 int dynls) 1006{ 1007 vint64 starttime; 1008 struct calendar fts; 1009 leap_info_t li; 1010 1011 /* Check that we either extend the table or get a duplicate of 1012 * the latest entry. The latter is a benevolent overwrite with 1013 * identical data and could happen if we get an autokey message 1014 * that extends the lifetime of the current leapsecond table. 1015 * Otherwise paranoia rulez! 1016 */ 1017 if (pt->head.size) { 1018 int cmp = ucmpv64(ttime, &pt->info[0].ttime); 1019 if (cmp == 0) 1020 cmp -= (taiof != pt->info[0].taiof); 1021 if (cmp < 0) { 1022 errno = ERANGE; 1023 return FALSE; 1024 } 1025 if (cmp == 0) 1026 return TRUE; 1027 } 1028 1029 ntpcal_ntp64_to_date(&fts, ttime); 1030 /* If this does not match the exact month start, bail out. */ 1031 if (fts.monthday != 1 || fts.hour || fts.minute || fts.second) { 1032 errno = EINVAL; 1033 return FALSE; 1034 } 1035 fts.month--; /* was in range 1..12, no overflow here! */ 1036 starttime = ntpcal_date_to_ntp64(&fts); 1037 li.ttime = *ttime; 1038 li.stime = ttime->D_s.lo - starttime.D_s.lo; 1039 li.taiof = (int16_t)taiof; 1040 li.dynls = (dynls != 0); 1041 return add_range(pt, &li); 1042} 1043 1044/* [internal] Do a wrap-around save range inclusion check. 1045 * Returns TRUE if x in [lo,hi[ (intervall open on right side) with full 1046 * handling of an overflow / wrap-around. 1047 */ 1048static int/*BOOL*/ 1049betweenu32( 1050 uint32_t lo, 1051 uint32_t x, 1052 uint32_t hi) 1053{ 1054 int rc; 1055 1056 if (lo <= hi) 1057 rc = (lo <= x) && (x < hi); 1058 else 1059 rc = (lo <= x) || (x < hi); 1060 return rc; 1061} 1062 1063/* ===================================================================== 1064 * validation stuff 1065 */ 1066 1067typedef struct { 1068 unsigned char hv[ISC_SHA1_DIGESTLENGTH]; 1069} sha1_digest; 1070 1071/* [internal] parse a digest line to get the hash signature 1072 * The NIST code creating the hash writes them out as 5 hex integers 1073 * without leading zeros. This makes reading them back as hex-encoded 1074 * BLOB impossible, because there might be less than 40 hex digits. 1075 * 1076 * The solution is to read the values back as integers, and then do the 1077 * byte twiddle necessary to get it into an array of 20 chars. The 1078 * drawback is that it permits any acceptable number syntax provided by 1079 * 'scanf()' and 'strtoul()', including optional signs and '0x' 1080 * prefixes. 1081 */ 1082static int/*BOOL*/ 1083do_leap_hash( 1084 sha1_digest * mac, 1085 char const * cp ) 1086{ 1087 int wi, di, num, len; 1088 unsigned long tmp[5]; 1089 1090 memset(mac, 0, sizeof(*mac)); 1091 num = sscanf(cp, " %lx %lx %lx %lx %lx%n", 1092 &tmp[0], &tmp[1], &tmp[2], &tmp[3], &tmp[4], 1093 &len); 1094 if (num != 5 || cp[len] > ' ') 1095 return FALSE; 1096 1097 /* now do the byte twiddle */ 1098 for (wi=0; wi < 5; ++wi) 1099 for (di=3; di >= 0; --di) { 1100 mac->hv[wi*4 + di] = 1101 (unsigned char)(tmp[wi] & 0x0FF); 1102 tmp[wi] >>= 8; 1103 } 1104 return TRUE; 1105} 1106 1107/* [internal] add the digits of a data line to the hash, stopping at the 1108 * next hash ('#') character. 1109 */ 1110static void 1111do_hash_data( 1112 isc_sha1_t * mdctx, 1113 char const * cp ) 1114{ 1115 unsigned char text[32]; // must be power of two! 1116 unsigned int tlen = 0; 1117 unsigned char ch; 1118 1119 while ('\0' != (ch = *cp++) && '#' != ch) 1120 if (isdigit(ch)) { 1121 text[tlen++] = ch; 1122 tlen &= (sizeof(text)-1); 1123 if (0 == tlen) 1124 isc_sha1_update( 1125 mdctx, text, sizeof(text)); 1126 } 1127 1128 if (0 < tlen) 1129 isc_sha1_update(mdctx, text, tlen); 1130} 1131 1132/* given a reader and a reader arg, calculate and validate the the hash 1133 * signature of a NIST leap second file. 1134 */ 1135int 1136leapsec_validate( 1137 leapsec_reader func, 1138 void * farg) 1139{ 1140 isc_sha1_t mdctx; 1141 sha1_digest rdig, ldig; /* remote / local digests */ 1142 char line[50]; 1143 int hlseen = -1; 1144 1145 isc_sha1_init(&mdctx); 1146 while (get_line(func, farg, line, sizeof(line))) { 1147 if (!strncmp(line, "#h", 2)) 1148 hlseen = do_leap_hash(&rdig, line+2); 1149 else if (!strncmp(line, "#@", 2)) 1150 do_hash_data(&mdctx, line+2); 1151 else if (!strncmp(line, "#$", 2)) 1152 do_hash_data(&mdctx, line+2); 1153 else if (isdigit((unsigned char)line[0])) 1154 do_hash_data(&mdctx, line); 1155 } 1156 isc_sha1_final(&mdctx, ldig.hv); 1157 isc_sha1_invalidate(&mdctx); 1158 1159 if (0 > hlseen) 1160 return LSVALID_NOHASH; 1161 if (0 == hlseen) 1162 return LSVALID_BADFORMAT; 1163 if (0 != memcmp(&rdig, &ldig, sizeof(sha1_digest))) 1164 return LSVALID_BADHASH; 1165 return LSVALID_GOODHASH; 1166} 1167 1168/* 1169 * lstostr - prettyprint NTP seconds 1170 */ 1171static const char * 1172lstostr( 1173 const vint64 * ts) 1174{ 1175 char * buf; 1176 struct calendar tm; 1177 1178 LIB_GETBUF(buf); 1179 1180 if ( ! (ts->d_s.hi >= 0 && ntpcal_ntp64_to_date(&tm, ts) >= 0)) 1181 snprintf(buf, LIB_BUFLENGTH, "%s", "9999-12-31T23:59:59Z"); 1182 else 1183 snprintf(buf, LIB_BUFLENGTH, "%04d-%02d-%02dT%02d:%02d:%02dZ", 1184 tm.year, tm.month, tm.monthday, 1185 tm.hour, tm.minute, tm.second); 1186 1187 return buf; 1188} 1189 1190/* reset the global state for unit tests */ 1191void 1192leapsec_ut_pristine(void) 1193{ 1194 memset(_ltab, 0, sizeof(_ltab)); 1195 _lptr = NULL; 1196 _electric = 0; 1197} 1198 1199 1200 1201/* -*- that's all folks! -*- */ 1202