ntp_leapsec.c revision 330106
1/* 2 * ntp_leapsec.c - leap second processing for NTPD 3 * 4 * Written by Juergen Perlinger (perlinger@ntp.org) for the NTP project. 5 * The contents of 'html/copyright.html' apply. 6 * ---------------------------------------------------------------------- 7 * This is an attempt to get the leap second handling into a dedicated 8 * module to make the somewhat convoluted logic testable. 9 */ 10 11#include <config.h> 12#include <sys/types.h> 13#include <sys/stat.h> 14#include <ctype.h> 15 16#include "ntp_types.h" 17#include "ntp_fp.h" 18#include "ntp_stdlib.h" 19#include "ntp_calendar.h" 20#include "ntp_leapsec.h" 21#include "ntp.h" 22#include "vint64ops.h" 23#include "lib_strbuf.h" 24 25#include "isc/sha1.h" 26 27static const char * const logPrefix = "leapsecond file"; 28 29/* --------------------------------------------------------------------- 30 * GCC is rather sticky with its 'const' attribute. We have to do it more 31 * explicit than with a cast if we want to get rid of a CONST qualifier. 32 * Greetings from the PASCAL world, where casting was only possible via 33 * untagged unions... 34 */ 35static inline void* 36noconst( 37 const void* ptr 38 ) 39{ 40 union { 41 const void * cp; 42 void * vp; 43 } tmp; 44 tmp.cp = ptr; 45 return tmp.vp; 46} 47 48/* --------------------------------------------------------------------- 49 * Our internal data structure 50 */ 51#define MAX_HIST 10 /* history of leap seconds */ 52 53struct leap_info { 54 vint64 ttime; /* transition time (after the step, ntp scale) */ 55 uint32_t stime; /* schedule limit (a month before transition) */ 56 int16_t taiof; /* TAI offset on and after the transition */ 57 uint8_t dynls; /* dynamic: inserted on peer/clock request */ 58}; 59typedef struct leap_info leap_info_t; 60 61struct leap_head { 62 vint64 update; /* time of information update */ 63 vint64 expire; /* table expiration time */ 64 uint16_t size; /* number of infos in table */ 65 int16_t base_tai; /* total leaps before first entry */ 66 int16_t this_tai; /* current TAI offset */ 67 int16_t next_tai; /* TAI offset after 'when' */ 68 vint64 dtime; /* due time (current era end) */ 69 vint64 ttime; /* nominal transition time (next era start) */ 70 vint64 stime; /* schedule time (when we take notice) */ 71 vint64 ebase; /* base time of this leap era */ 72 uint8_t dynls; /* next leap is dynamic (by peer request) */ 73}; 74typedef struct leap_head leap_head_t; 75 76struct leap_table { 77 leap_signature_t lsig; 78 leap_head_t head; 79 leap_info_t info[MAX_HIST]; 80}; 81 82/* Where we store our tables */ 83static leap_table_t _ltab[2], *_lptr; 84static int/*BOOL*/ _electric; 85 86/* Forward decls of local helpers */ 87static int add_range(leap_table_t*, const leap_info_t*); 88static char * get_line(leapsec_reader, void*, char*, size_t); 89static char * skipws(const char*); 90static int parsefail(const char * cp, const char * ep); 91static void reload_limits(leap_table_t*, const vint64*); 92static void fetch_leap_era(leap_era_t*, const leap_table_t*, 93 const vint64*); 94static int betweenu32(uint32_t, uint32_t, uint32_t); 95static void reset_times(leap_table_t*); 96static int leapsec_add(leap_table_t*, const vint64*, int); 97static int leapsec_raw(leap_table_t*, const vint64 *, int, int); 98static const char * lstostr(const vint64 * ts); 99 100/* ===================================================================== 101 * Get & Set the current leap table 102 */ 103 104/* ------------------------------------------------------------------ */ 105leap_table_t * 106leapsec_get_table( 107 int alternate) 108{ 109 leap_table_t *p1, *p2; 110 111 p1 = _lptr; 112 if (p1 == &_ltab[0]) { 113 p2 = &_ltab[1]; 114 } else if (p1 == &_ltab[1]) { 115 p2 = &_ltab[0]; 116 } else { 117 p1 = &_ltab[0]; 118 p2 = &_ltab[1]; 119 reset_times(p1); 120 reset_times(p2); 121 _lptr = p1; 122 } 123 if (alternate) { 124 memcpy(p2, p1, sizeof(leap_table_t)); 125 p1 = p2; 126 } 127 128 return p1; 129} 130 131/* ------------------------------------------------------------------ */ 132int/*BOOL*/ 133leapsec_set_table( 134 leap_table_t * pt) 135{ 136 if (pt == &_ltab[0] || pt == &_ltab[1]) 137 _lptr = pt; 138 return _lptr == pt; 139} 140 141/* ------------------------------------------------------------------ */ 142int/*BOOL*/ 143leapsec_electric( 144 int/*BOOL*/ on) 145{ 146 int res = _electric; 147 if (on < 0) 148 return res; 149 150 _electric = (on != 0); 151 if (_electric == res) 152 return res; 153 154 if (_lptr == &_ltab[0] || _lptr == &_ltab[1]) 155 reset_times(_lptr); 156 157 return res; 158} 159 160/* ===================================================================== 161 * API functions that operate on tables 162 */ 163 164/* --------------------------------------------------------------------- 165 * Clear all leap second data. Use it for init & cleanup 166 */ 167void 168leapsec_clear( 169 leap_table_t * pt) 170{ 171 memset(&pt->lsig, 0, sizeof(pt->lsig)); 172 memset(&pt->head, 0, sizeof(pt->head)); 173 reset_times(pt); 174} 175 176/* --------------------------------------------------------------------- 177 * Load a leap second file and check expiration on the go 178 */ 179int/*BOOL*/ 180leapsec_load( 181 leap_table_t * pt , 182 leapsec_reader func, 183 void * farg, 184 int use_build_limit) 185{ 186 char *cp, *ep, linebuf[50]; 187 vint64 ttime, limit; 188 long taiof; 189 struct calendar build; 190 191 leapsec_clear(pt); 192 if (use_build_limit && ntpcal_get_build_date(&build)) { 193 /* don't prune everything -- permit the last 10yrs 194 * before build. 195 */ 196 build.year -= 10; 197 limit = ntpcal_date_to_ntp64(&build); 198 } else { 199 memset(&limit, 0, sizeof(limit)); 200 } 201 202 while (get_line(func, farg, linebuf, sizeof(linebuf))) { 203 cp = linebuf; 204 if (*cp == '#') { 205 cp++; 206 if (*cp == '@') { 207 cp = skipws(cp+1); 208 pt->head.expire = strtouv64(cp, &ep, 10); 209 if (parsefail(cp, ep)) 210 goto fail_read; 211 pt->lsig.etime = pt->head.expire.D_s.lo; 212 } else if (*cp == '$') { 213 cp = skipws(cp+1); 214 pt->head.update = strtouv64(cp, &ep, 10); 215 if (parsefail(cp, ep)) 216 goto fail_read; 217 } 218 } else if (isdigit((u_char)*cp)) { 219 ttime = strtouv64(cp, &ep, 10); 220 if (parsefail(cp, ep)) 221 goto fail_read; 222 cp = skipws(ep); 223 taiof = strtol(cp, &ep, 10); 224 if ( parsefail(cp, ep) 225 || taiof > SHRT_MAX || taiof < SHRT_MIN) 226 goto fail_read; 227 if (ucmpv64(&ttime, &limit) >= 0) { 228 if (!leapsec_raw(pt, &ttime, 229 taiof, FALSE)) 230 goto fail_insn; 231 } else { 232 pt->head.base_tai = (int16_t)taiof; 233 } 234 pt->lsig.ttime = ttime.D_s.lo; 235 pt->lsig.taiof = (int16_t)taiof; 236 } 237 } 238 return TRUE; 239 240fail_read: 241 errno = EILSEQ; 242fail_insn: 243 leapsec_clear(pt); 244 return FALSE; 245} 246 247/* --------------------------------------------------------------------- 248 * Dump a table in human-readable format. Use 'fprintf' and a FILE 249 * pointer if you want to get it printed into a stream. 250 */ 251void 252leapsec_dump( 253 const leap_table_t * pt , 254 leapsec_dumper func, 255 void * farg) 256{ 257 int idx; 258 vint64 ts; 259 struct calendar atb, ttb; 260 261 ntpcal_ntp64_to_date(&ttb, &pt->head.expire); 262 (*func)(farg, "leap table (%u entries) expires at %04u-%02u-%02u:\n", 263 pt->head.size, 264 ttb.year, ttb.month, ttb.monthday); 265 idx = pt->head.size; 266 while (idx-- != 0) { 267 ts = pt->info[idx].ttime; 268 ntpcal_ntp64_to_date(&ttb, &ts); 269 ts = subv64u32(&ts, pt->info[idx].stime); 270 ntpcal_ntp64_to_date(&atb, &ts); 271 272 (*func)(farg, "%04u-%02u-%02u [%c] (%04u-%02u-%02u) - %d\n", 273 ttb.year, ttb.month, ttb.monthday, 274 "-*"[pt->info[idx].dynls != 0], 275 atb.year, atb.month, atb.monthday, 276 pt->info[idx].taiof); 277 } 278} 279 280/* ===================================================================== 281 * usecase driven API functions 282 */ 283 284int/*BOOL*/ 285leapsec_query( 286 leap_result_t * qr , 287 uint32_t ts32 , 288 const time_t * pivot) 289{ 290 leap_table_t * pt; 291 vint64 ts64, last, next; 292 uint32_t due32; 293 int fired; 294 295 /* preset things we use later on... */ 296 fired = FALSE; 297 ts64 = ntpcal_ntp_to_ntp(ts32, pivot); 298 pt = leapsec_get_table(FALSE); 299 memset(qr, 0, sizeof(leap_result_t)); 300 301 if (ucmpv64(&ts64, &pt->head.ebase) < 0) { 302 /* Most likely after leap frame reset. Could also be a 303 * backstep of the system clock. Anyway, get the new 304 * leap era frame. 305 */ 306 reload_limits(pt, &ts64); 307 } else if (ucmpv64(&ts64, &pt->head.dtime) >= 0) { 308 /* Boundary crossed in forward direction. This might 309 * indicate a leap transition, so we prepare for that 310 * case. 311 * 312 * Some operations below are actually NOPs in electric 313 * mode, but having only one code path that works for 314 * both modes is easier to maintain. 315 * 316 * There's another quirk we must keep looking out for: 317 * If we just stepped the clock, the step might have 318 * crossed a leap boundary. As with backward steps, we 319 * do not want to raise the 'fired' event in that case. 320 * So we raise the 'fired' event only if we're close to 321 * the transition and just reload the limits otherwise. 322 */ 323 last = addv64i32(&pt->head.dtime, 3); /* get boundary */ 324 if (ucmpv64(&ts64, &last) >= 0) { 325 /* that was likely a query after a step */ 326 reload_limits(pt, &ts64); 327 } else { 328 /* close enough for deeper examination */ 329 last = pt->head.ttime; 330 qr->warped = (int16_t)(last.D_s.lo - 331 pt->head.dtime.D_s.lo); 332 next = addv64i32(&ts64, qr->warped); 333 reload_limits(pt, &next); 334 fired = ucmpv64(&pt->head.ebase, &last) == 0; 335 if (fired) { 336 ts64 = next; 337 ts32 = next.D_s.lo; 338 } else { 339 qr->warped = 0; 340 } 341 } 342 } 343 344 qr->tai_offs = pt->head.this_tai; 345 qr->ebase = pt->head.ebase; 346 qr->ttime = pt->head.ttime; 347 348 /* If before the next scheduling alert, we're done. */ 349 if (ucmpv64(&ts64, &pt->head.stime) < 0) 350 return fired; 351 352 /* now start to collect the remaining data */ 353 due32 = pt->head.dtime.D_s.lo; 354 355 qr->tai_diff = pt->head.next_tai - pt->head.this_tai; 356 qr->ddist = due32 - ts32; 357 qr->dynamic = pt->head.dynls; 358 qr->proximity = LSPROX_SCHEDULE; 359 360 /* if not in the last day before transition, we're done. */ 361 if (!betweenu32(due32 - SECSPERDAY, ts32, due32)) 362 return fired; 363 364 qr->proximity = LSPROX_ANNOUNCE; 365 if (!betweenu32(due32 - 10, ts32, due32)) 366 return fired; 367 368 /* The last 10s before the transition. Prepare for action! */ 369 qr->proximity = LSPROX_ALERT; 370 return fired; 371} 372 373/* ------------------------------------------------------------------ */ 374int/*BOOL*/ 375leapsec_query_era( 376 leap_era_t * qr , 377 uint32_t ntpts, 378 const time_t * pivot) 379{ 380 const leap_table_t * pt; 381 vint64 ts64; 382 383 pt = leapsec_get_table(FALSE); 384 ts64 = ntpcal_ntp_to_ntp(ntpts, pivot); 385 fetch_leap_era(qr, pt, &ts64); 386 return TRUE; 387} 388 389/* ------------------------------------------------------------------ */ 390int/*BOOL*/ 391leapsec_frame( 392 leap_result_t *qr) 393{ 394 const leap_table_t * pt; 395 396 memset(qr, 0, sizeof(leap_result_t)); 397 pt = leapsec_get_table(FALSE); 398 399 qr->tai_offs = pt->head.this_tai; 400 qr->tai_diff = pt->head.next_tai - pt->head.this_tai; 401 qr->ebase = pt->head.ebase; 402 qr->ttime = pt->head.ttime; 403 qr->dynamic = pt->head.dynls; 404 405 return ucmpv64(&pt->head.ttime, &pt->head.stime) >= 0; 406} 407 408/* ------------------------------------------------------------------ */ 409/* Reset the current leap frame */ 410void 411leapsec_reset_frame(void) 412{ 413 reset_times(leapsec_get_table(FALSE)); 414} 415 416/* ------------------------------------------------------------------ */ 417/* load a file from a FILE pointer. Note: If hcheck is true, load 418 * only after successful signature check. The stream must be seekable 419 * or this will fail. 420 */ 421int/*BOOL*/ 422leapsec_load_stream( 423 FILE * ifp , 424 const char * fname, 425 int/*BOOL*/ logall) 426{ 427 leap_table_t *pt; 428 int rcheck; 429 430 if (NULL == fname) 431 fname = "<unknown>"; 432 433 rcheck = leapsec_validate((leapsec_reader)getc, ifp); 434 if (logall) 435 switch (rcheck) 436 { 437 case LSVALID_GOODHASH: 438 msyslog(LOG_NOTICE, "%s ('%s'): good hash signature", 439 logPrefix, fname); 440 break; 441 442 case LSVALID_NOHASH: 443 msyslog(LOG_ERR, "%s ('%s'): no hash signature", 444 logPrefix, fname); 445 break; 446 case LSVALID_BADHASH: 447 msyslog(LOG_ERR, "%s ('%s'): signature mismatch", 448 logPrefix, fname); 449 break; 450 case LSVALID_BADFORMAT: 451 msyslog(LOG_ERR, "%s ('%s'): malformed hash signature", 452 logPrefix, fname); 453 break; 454 default: 455 msyslog(LOG_ERR, "%s ('%s'): unknown error code %d", 456 logPrefix, fname, rcheck); 457 break; 458 } 459 if (rcheck < 0) 460 return FALSE; 461 462 rewind(ifp); 463 pt = leapsec_get_table(TRUE); 464 if (!leapsec_load(pt, (leapsec_reader)getc, ifp, TRUE)) { 465 switch (errno) { 466 case EINVAL: 467 msyslog(LOG_ERR, "%s ('%s'): bad transition time", 468 logPrefix, fname); 469 break; 470 case ERANGE: 471 msyslog(LOG_ERR, "%s ('%s'): times not ascending", 472 logPrefix, fname); 473 break; 474 default: 475 msyslog(LOG_ERR, "%s ('%s'): parsing error", 476 logPrefix, fname); 477 break; 478 } 479 return FALSE; 480 } 481 482 if (pt->head.size) 483 msyslog(LOG_NOTICE, "%s ('%s'): loaded, expire=%s last=%s ofs=%d", 484 logPrefix, fname, lstostr(&pt->head.expire), 485 lstostr(&pt->info[0].ttime), pt->info[0].taiof); 486 else 487 msyslog(LOG_NOTICE, 488 "%s ('%s'): loaded, expire=%s ofs=%d (no entries after build date)", 489 logPrefix, fname, lstostr(&pt->head.expire), 490 pt->head.base_tai); 491 492 return leapsec_set_table(pt); 493} 494 495/* ------------------------------------------------------------------ */ 496int/*BOOL*/ 497leapsec_load_file( 498 const char * fname, 499 struct stat * sb_old, 500 int/*BOOL*/ force, 501 int/*BOOL*/ logall) 502{ 503 FILE * fp; 504 struct stat sb_new; 505 int rc; 506 507 /* just do nothing if there is no leap file */ 508 if ( !(fname && *fname) ) 509 return FALSE; 510 511 /* try to stat the leapfile */ 512 if (0 != stat(fname, &sb_new)) { 513 if (logall) 514 msyslog(LOG_ERR, "%s ('%s'): stat failed: %m", 515 logPrefix, fname); 516 return FALSE; 517 } 518 519 /* silently skip to postcheck if no new file found */ 520 if (NULL != sb_old) { 521 if (!force 522 && sb_old->st_mtime == sb_new.st_mtime 523 && sb_old->st_ctime == sb_new.st_ctime 524 ) 525 return FALSE; 526 *sb_old = sb_new; 527 } 528 529 /* try to open the leap file, complain if that fails 530 * 531 * [perlinger@ntp.org] 532 * coverity raises a TOCTOU (time-of-check/time-of-use) issue 533 * here, which is not entirely helpful: While there is indeed a 534 * possible race condition between the 'stat()' call above and 535 * the 'fopen)' call below, I intentionally want to omit the 536 * overhead of opening the file and calling 'fstat()', because 537 * in most cases the file would have be to closed anyway without 538 * reading the contents. I chose to disable the coverity 539 * warning instead. 540 * 541 * So unless someone comes up with a reasonable argument why 542 * this could be a real issue, I'll just try to silence coverity 543 * on that topic. 544 */ 545 /* coverity[toctou] */ 546 if ((fp = fopen(fname, "r")) == NULL) { 547 if (logall) 548 msyslog(LOG_ERR, 549 "%s ('%s'): open failed: %m", 550 logPrefix, fname); 551 return FALSE; 552 } 553 554 rc = leapsec_load_stream(fp, fname, logall); 555 fclose(fp); 556 return rc; 557} 558 559/* ------------------------------------------------------------------ */ 560void 561leapsec_getsig( 562 leap_signature_t * psig) 563{ 564 const leap_table_t * pt; 565 566 pt = leapsec_get_table(FALSE); 567 memcpy(psig, &pt->lsig, sizeof(leap_signature_t)); 568} 569 570/* ------------------------------------------------------------------ */ 571int/*BOOL*/ 572leapsec_expired( 573 uint32_t when, 574 const time_t * tpiv) 575{ 576 const leap_table_t * pt; 577 vint64 limit; 578 579 pt = leapsec_get_table(FALSE); 580 limit = ntpcal_ntp_to_ntp(when, tpiv); 581 return ucmpv64(&limit, &pt->head.expire) >= 0; 582} 583 584/* ------------------------------------------------------------------ */ 585int32_t 586leapsec_daystolive( 587 uint32_t when, 588 const time_t * tpiv) 589{ 590 const leap_table_t * pt; 591 vint64 limit; 592 593 pt = leapsec_get_table(FALSE); 594 limit = ntpcal_ntp_to_ntp(when, tpiv); 595 limit = subv64(&pt->head.expire, &limit); 596 return ntpcal_daysplit(&limit).hi; 597} 598 599/* ------------------------------------------------------------------ */ 600#if 0 /* currently unused -- possibly revived later */ 601int/*BOOL*/ 602leapsec_add_fix( 603 int total, 604 uint32_t ttime, 605 uint32_t etime, 606 const time_t * pivot) 607{ 608 time_t tpiv; 609 leap_table_t * pt; 610 vint64 tt64, et64; 611 612 if (pivot == NULL) { 613 time(&tpiv); 614 pivot = &tpiv; 615 } 616 617 et64 = ntpcal_ntp_to_ntp(etime, pivot); 618 tt64 = ntpcal_ntp_to_ntp(ttime, pivot); 619 pt = leapsec_get_table(TRUE); 620 621 if ( ucmpv64(&et64, &pt->head.expire) <= 0 622 || !leapsec_raw(pt, &tt64, total, FALSE) ) 623 return FALSE; 624 625 pt->lsig.etime = etime; 626 pt->lsig.ttime = ttime; 627 pt->lsig.taiof = (int16_t)total; 628 629 pt->head.expire = et64; 630 631 return leapsec_set_table(pt); 632} 633#endif 634 635/* ------------------------------------------------------------------ */ 636int/*BOOL*/ 637leapsec_add_dyn( 638 int insert, 639 uint32_t ntpnow, 640 const time_t * pivot ) 641{ 642 leap_table_t * pt; 643 vint64 now64; 644 645 pt = leapsec_get_table(TRUE); 646 now64 = ntpcal_ntp_to_ntp(ntpnow, pivot); 647 return ( leapsec_add(pt, &now64, (insert != 0)) 648 && leapsec_set_table(pt)); 649} 650 651/* ------------------------------------------------------------------ */ 652int/*BOOL*/ 653leapsec_autokey_tai( 654 int tai_offset, 655 uint32_t ntpnow , 656 const time_t * pivot ) 657{ 658 leap_table_t * pt; 659 leap_era_t era; 660 vint64 now64; 661 int idx; 662 663 (void)tai_offset; 664 pt = leapsec_get_table(FALSE); 665 666 /* Bail out if the basic offset is not zero and the putative 667 * offset is bigger than 10s. That was in 1972 -- we don't want 668 * to go back that far! 669 */ 670 if (pt->head.base_tai != 0 || tai_offset < 10) 671 return FALSE; 672 673 /* If there's already data in the table, check if an update is 674 * possible. Update is impossible if there are static entries 675 * (since this indicates a valid leapsecond file) or if we're 676 * too close to a leapsecond transition: We do not know on what 677 * side the transition the sender might have been, so we use a 678 * dead zone around the transition. 679 */ 680 681 /* Check for static entries */ 682 for (idx = 0; idx != pt->head.size; idx++) 683 if ( ! pt->info[idx].dynls) 684 return FALSE; 685 686 /* get the fulll time stamp and leap era for it */ 687 now64 = ntpcal_ntp_to_ntp(ntpnow, pivot); 688 fetch_leap_era(&era, pt, &now64); 689 690 /* check the limits with 20s dead band */ 691 era.ebase = addv64i32(&era.ebase, 20); 692 if (ucmpv64(&now64, &era.ebase) < 0) 693 return FALSE; 694 695 era.ttime = addv64i32(&era.ttime, -20); 696 if (ucmpv64(&now64, &era.ttime) > 0) 697 return FALSE; 698 699 /* Here we can proceed. Calculate the delta update. */ 700 tai_offset -= era.taiof; 701 702 /* Shift the header info offsets. */ 703 pt->head.base_tai += tai_offset; 704 pt->head.this_tai += tai_offset; 705 pt->head.next_tai += tai_offset; 706 707 /* Shift table entry offsets (if any) */ 708 for (idx = 0; idx != pt->head.size; idx++) 709 pt->info[idx].taiof += tai_offset; 710 711 /* claim success... */ 712 return TRUE; 713} 714 715 716/* ===================================================================== 717 * internal helpers 718 */ 719 720/* [internal] Reset / init the time window in the leap processor to 721 * force reload on next query. Since a leap transition cannot take place 722 * at an odd second, the value chosen avoids spurious leap transition 723 * triggers. Making all three times equal forces a reload. Using the 724 * maximum value for unsigned 64 bits makes finding the next leap frame 725 * a bit easier. 726 */ 727static void 728reset_times( 729 leap_table_t * pt) 730{ 731 memset(&pt->head.ebase, 0xFF, sizeof(vint64)); 732 pt->head.stime = pt->head.ebase; 733 pt->head.ttime = pt->head.ebase; 734 pt->head.dtime = pt->head.ebase; 735} 736 737/* [internal] Add raw data to the table, removing old entries on the 738 * fly. This cannot fail currently. 739 */ 740static int/*BOOL*/ 741add_range( 742 leap_table_t * pt, 743 const leap_info_t * pi) 744{ 745 /* If the table is full, make room by throwing out the oldest 746 * entry. But remember the accumulated leap seconds! 747 * 748 * Setting the first entry is a bit tricky, too: Simply assuming 749 * it is an insertion is wrong if the first entry is a dynamic 750 * leap second removal. So we decide on the sign -- if the first 751 * entry has a negative offset, we assume that it is a leap 752 * second removal. In both cases the table base offset is set 753 * accordingly to reflect the decision. 754 * 755 * In practice starting with a removal can only happen if the 756 * first entry is a dynamic request without having a leap file 757 * for the history proper. 758 */ 759 if (pt->head.size == 0) { 760 if (pi->taiof >= 0) 761 pt->head.base_tai = pi->taiof - 1; 762 else 763 pt->head.base_tai = pi->taiof + 1; 764 } else if (pt->head.size >= MAX_HIST) { 765 pt->head.size = MAX_HIST - 1; 766 pt->head.base_tai = pt->info[pt->head.size].taiof; 767 } 768 769 /* make room in lower end and insert item */ 770 memmove(pt->info+1, pt->info, pt->head.size*sizeof(*pt->info)); 771 pt->info[0] = *pi; 772 pt->head.size++; 773 774 /* invalidate the cached limit data -- we might have news ;-) 775 * 776 * This blocks a spurious transition detection. OTOH, if you add 777 * a value after the last query before a leap transition was 778 * expected to occur, this transition trigger is lost. But we 779 * can probably live with that. 780 */ 781 reset_times(pt); 782 return TRUE; 783} 784 785/* [internal] given a reader function, read characters into a buffer 786 * until either EOL or EOF is reached. Makes sure that the buffer is 787 * always NUL terminated, but silently truncates excessive data. The 788 * EOL-marker ('\n') is *not* stored in the buffer. 789 * 790 * Returns the pointer to the buffer, unless EOF was reached when trying 791 * to read the first character of a line. 792 */ 793static char * 794get_line( 795 leapsec_reader func, 796 void * farg, 797 char * buff, 798 size_t size) 799{ 800 int ch; 801 char *ptr; 802 803 /* if we cannot even store the delimiter, declare failure */ 804 if (buff == NULL || size == 0) 805 return NULL; 806 807 ptr = buff; 808 while (EOF != (ch = (*func)(farg)) && '\n' != ch) 809 if (size > 1) { 810 size--; 811 *ptr++ = (char)ch; 812 } 813 /* discard trailing whitespace */ 814 while (ptr != buff && isspace((u_char)ptr[-1])) 815 ptr--; 816 *ptr = '\0'; 817 return (ptr == buff && ch == EOF) ? NULL : buff; 818} 819 820/* [internal] skips whitespace characters from a character buffer. */ 821static char * 822skipws( 823 const char *ptr) 824{ 825 while (isspace((u_char)*ptr)) 826 ptr++; 827 return (char*)noconst(ptr); 828} 829 830/* [internal] check if a strtoXYZ ended at EOL or whitespace and 831 * converted something at all. Return TRUE if something went wrong. 832 */ 833static int/*BOOL*/ 834parsefail( 835 const char * cp, 836 const char * ep) 837{ 838 return (cp == ep) 839 || (*ep && *ep != '#' && !isspace((u_char)*ep)); 840} 841 842/* [internal] reload the table limits around the given time stamp. This 843 * is where the real work is done when it comes to table lookup and 844 * evaluation. Some care has been taken to have correct code for dealing 845 * with boundary conditions and empty tables. 846 * 847 * In electric mode, transition and trip time are the same. In dumb 848 * mode, the difference of the TAI offsets must be taken into account 849 * and trip time and transition time become different. The difference 850 * becomes the warping distance when the trip time is reached. 851 */ 852static void 853reload_limits( 854 leap_table_t * pt, 855 const vint64 * ts) 856{ 857 int idx; 858 859 /* Get full time and search the true lower bound. Use a 860 * simple loop here, since the number of entries does 861 * not warrant a binary search. This also works for an empty 862 * table, so there is no shortcut for that case. 863 */ 864 for (idx = 0; idx != pt->head.size; idx++) 865 if (ucmpv64(ts, &pt->info[idx].ttime) >= 0) 866 break; 867 868 /* get time limits with proper bound conditions. Note that the 869 * bounds of the table will be observed even if the table is 870 * empty -- no undefined condition must arise from this code. 871 */ 872 if (idx >= pt->head.size) { 873 memset(&pt->head.ebase, 0x00, sizeof(vint64)); 874 pt->head.this_tai = pt->head.base_tai; 875 } else { 876 pt->head.ebase = pt->info[idx].ttime; 877 pt->head.this_tai = pt->info[idx].taiof; 878 } 879 if (--idx >= 0) { 880 pt->head.next_tai = pt->info[idx].taiof; 881 pt->head.dynls = pt->info[idx].dynls; 882 pt->head.ttime = pt->info[idx].ttime; 883 884 if (_electric) 885 pt->head.dtime = pt->head.ttime; 886 else 887 pt->head.dtime = addv64i32( 888 &pt->head.ttime, 889 pt->head.next_tai - pt->head.this_tai); 890 891 pt->head.stime = subv64u32( 892 &pt->head.ttime, pt->info[idx].stime); 893 894 } else { 895 memset(&pt->head.ttime, 0xFF, sizeof(vint64)); 896 pt->head.stime = pt->head.ttime; 897 pt->head.dtime = pt->head.ttime; 898 pt->head.next_tai = pt->head.this_tai; 899 pt->head.dynls = 0; 900 } 901} 902 903/* [internal] fetch the leap era for a given time stamp. 904 * This is a cut-down version the algorithm used to reload the table 905 * limits, but it does not update any global state and provides just the 906 * era information for a given time stamp. 907 */ 908static void 909fetch_leap_era( 910 leap_era_t * into, 911 const leap_table_t * pt , 912 const vint64 * ts ) 913{ 914 int idx; 915 916 /* Simple search loop, also works with empty table. */ 917 for (idx = 0; idx != pt->head.size; idx++) 918 if (ucmpv64(ts, &pt->info[idx].ttime) >= 0) 919 break; 920 /* fetch era data, keeping an eye on boundary conditions */ 921 if (idx >= pt->head.size) { 922 memset(&into->ebase, 0x00, sizeof(vint64)); 923 into->taiof = pt->head.base_tai; 924 } else { 925 into->ebase = pt->info[idx].ttime; 926 into->taiof = pt->info[idx].taiof; 927 } 928 if (--idx >= 0) 929 into->ttime = pt->info[idx].ttime; 930 else 931 memset(&into->ttime, 0xFF, sizeof(vint64)); 932} 933 934/* [internal] Take a time stamp and create a leap second frame for 935 * it. This will schedule a leap second for the beginning of the next 936 * month, midnight UTC. The 'insert' argument tells if a leap second is 937 * added (!=0) or removed (==0). We do not handle multiple inserts 938 * (yet?) 939 * 940 * Returns 1 if the insert worked, 0 otherwise. (It's not possible to 941 * insert a leap second into the current history -- only appending 942 * towards the future is allowed!) 943 */ 944static int/*BOOL*/ 945leapsec_add( 946 leap_table_t* pt , 947 const vint64 * now64 , 948 int insert) 949{ 950 vint64 ttime, starttime; 951 struct calendar fts; 952 leap_info_t li; 953 954 /* Check against the table expiration and the latest available 955 * leap entry. Do not permit inserts, only appends, and only if 956 * the extend the table beyond the expiration! 957 */ 958 if ( ucmpv64(now64, &pt->head.expire) < 0 959 || (pt->head.size && ucmpv64(now64, &pt->info[0].ttime) <= 0)) { 960 errno = ERANGE; 961 return FALSE; 962 } 963 964 ntpcal_ntp64_to_date(&fts, now64); 965 /* To guard against dangling leap flags: do not accept leap 966 * second request on the 1st hour of the 1st day of the month. 967 */ 968 if (fts.monthday == 1 && fts.hour == 0) { 969 errno = EINVAL; 970 return FALSE; 971 } 972 973 /* Ok, do the remaining calculations */ 974 fts.monthday = 1; 975 fts.hour = 0; 976 fts.minute = 0; 977 fts.second = 0; 978 starttime = ntpcal_date_to_ntp64(&fts); 979 fts.month++; 980 ttime = ntpcal_date_to_ntp64(&fts); 981 982 li.ttime = ttime; 983 li.stime = ttime.D_s.lo - starttime.D_s.lo; 984 li.taiof = (pt->head.size ? pt->info[0].taiof : pt->head.base_tai) 985 + (insert ? 1 : -1); 986 li.dynls = 1; 987 return add_range(pt, &li); 988} 989 990/* [internal] Given a time stamp for a leap insertion (the exact begin 991 * of the new leap era), create new leap frame and put it into the 992 * table. This is the work horse for reading a leap file and getting a 993 * leap second update via authenticated network packet. 994 */ 995int/*BOOL*/ 996leapsec_raw( 997 leap_table_t * pt, 998 const vint64 * ttime, 999 int taiof, 1000 int dynls) 1001{ 1002 vint64 starttime; 1003 struct calendar fts; 1004 leap_info_t li; 1005 1006 /* Check that we either extend the table or get a duplicate of 1007 * the latest entry. The latter is a benevolent overwrite with 1008 * identical data and could happen if we get an autokey message 1009 * that extends the lifetime of the current leapsecond table. 1010 * Otherwise paranoia rulez! 1011 */ 1012 if (pt->head.size) { 1013 int cmp = ucmpv64(ttime, &pt->info[0].ttime); 1014 if (cmp == 0) 1015 cmp -= (taiof != pt->info[0].taiof); 1016 if (cmp < 0) { 1017 errno = ERANGE; 1018 return FALSE; 1019 } 1020 if (cmp == 0) 1021 return TRUE; 1022 } 1023 1024 ntpcal_ntp64_to_date(&fts, ttime); 1025 /* If this does not match the exact month start, bail out. */ 1026 if (fts.monthday != 1 || fts.hour || fts.minute || fts.second) { 1027 errno = EINVAL; 1028 return FALSE; 1029 } 1030 fts.month--; /* was in range 1..12, no overflow here! */ 1031 starttime = ntpcal_date_to_ntp64(&fts); 1032 li.ttime = *ttime; 1033 li.stime = ttime->D_s.lo - starttime.D_s.lo; 1034 li.taiof = (int16_t)taiof; 1035 li.dynls = (dynls != 0); 1036 return add_range(pt, &li); 1037} 1038 1039/* [internal] Do a wrap-around save range inclusion check. 1040 * Returns TRUE if x in [lo,hi[ (intervall open on right side) with full 1041 * handling of an overflow / wrap-around. 1042 */ 1043static int/*BOOL*/ 1044betweenu32( 1045 uint32_t lo, 1046 uint32_t x, 1047 uint32_t hi) 1048{ 1049 int rc; 1050 1051 if (lo <= hi) 1052 rc = (lo <= x) && (x < hi); 1053 else 1054 rc = (lo <= x) || (x < hi); 1055 return rc; 1056} 1057 1058/* ===================================================================== 1059 * validation stuff 1060 */ 1061 1062typedef struct { 1063 unsigned char hv[ISC_SHA1_DIGESTLENGTH]; 1064} sha1_digest; 1065 1066/* [internal] parse a digest line to get the hash signature 1067 * The NIST code creating the hash writes them out as 5 hex integers 1068 * without leading zeros. This makes reading them back as hex-encoded 1069 * BLOB impossible, because there might be less than 40 hex digits. 1070 * 1071 * The solution is to read the values back as integers, and then do the 1072 * byte twiddle necessary to get it into an array of 20 chars. The 1073 * drawback is that it permits any acceptable number syntax provided by 1074 * 'scanf()' and 'strtoul()', including optional signs and '0x' 1075 * prefixes. 1076 */ 1077static int/*BOOL*/ 1078do_leap_hash( 1079 sha1_digest * mac, 1080 char const * cp ) 1081{ 1082 int wi, di, num, len; 1083 unsigned long tmp[5]; 1084 1085 memset(mac, 0, sizeof(*mac)); 1086 num = sscanf(cp, " %lx %lx %lx %lx %lx%n", 1087 &tmp[0], &tmp[1], &tmp[2], &tmp[3], &tmp[4], 1088 &len); 1089 if (num != 5 || cp[len] > ' ') 1090 return FALSE; 1091 1092 /* now do the byte twiddle */ 1093 for (wi=0; wi < 5; ++wi) 1094 for (di=3; di >= 0; --di) { 1095 mac->hv[wi*4 + di] = 1096 (unsigned char)(tmp[wi] & 0x0FF); 1097 tmp[wi] >>= 8; 1098 } 1099 return TRUE; 1100} 1101 1102/* [internal] add the digits of a data line to the hash, stopping at the 1103 * next hash ('#') character. 1104 */ 1105static void 1106do_hash_data( 1107 isc_sha1_t * mdctx, 1108 char const * cp ) 1109{ 1110 unsigned char text[32]; // must be power of two! 1111 unsigned int tlen = 0; 1112 unsigned char ch; 1113 1114 while ('\0' != (ch = *cp++) && '#' != ch) 1115 if (isdigit(ch)) { 1116 text[tlen++] = ch; 1117 tlen &= (sizeof(text)-1); 1118 if (0 == tlen) 1119 isc_sha1_update( 1120 mdctx, text, sizeof(text)); 1121 } 1122 1123 if (0 < tlen) 1124 isc_sha1_update(mdctx, text, tlen); 1125} 1126 1127/* given a reader and a reader arg, calculate and validate the the hash 1128 * signature of a NIST leap second file. 1129 */ 1130int 1131leapsec_validate( 1132 leapsec_reader func, 1133 void * farg) 1134{ 1135 isc_sha1_t mdctx; 1136 sha1_digest rdig, ldig; /* remote / local digests */ 1137 char line[50]; 1138 int hlseen = -1; 1139 1140 isc_sha1_init(&mdctx); 1141 while (get_line(func, farg, line, sizeof(line))) { 1142 if (!strncmp(line, "#h", 2)) 1143 hlseen = do_leap_hash(&rdig, line+2); 1144 else if (!strncmp(line, "#@", 2)) 1145 do_hash_data(&mdctx, line+2); 1146 else if (!strncmp(line, "#$", 2)) 1147 do_hash_data(&mdctx, line+2); 1148 else if (isdigit((unsigned char)line[0])) 1149 do_hash_data(&mdctx, line); 1150 } 1151 isc_sha1_final(&mdctx, ldig.hv); 1152 isc_sha1_invalidate(&mdctx); 1153 1154 if (0 > hlseen) 1155 return LSVALID_NOHASH; 1156 if (0 == hlseen) 1157 return LSVALID_BADFORMAT; 1158 if (0 != memcmp(&rdig, &ldig, sizeof(sha1_digest))) 1159 return LSVALID_BADHASH; 1160 return LSVALID_GOODHASH; 1161} 1162 1163/* 1164 * lstostr - prettyprint NTP seconds 1165 */ 1166static const char * 1167lstostr( 1168 const vint64 * ts) 1169{ 1170 char * buf; 1171 struct calendar tm; 1172 1173 LIB_GETBUF(buf); 1174 1175 if ( ! (ts->d_s.hi >= 0 && ntpcal_ntp64_to_date(&tm, ts) >= 0)) 1176 snprintf(buf, LIB_BUFLENGTH, "%s", "9999-12-31T23:59:59Z"); 1177 else 1178 snprintf(buf, LIB_BUFLENGTH, "%04d-%02d-%02dT%02d:%02d:%02dZ", 1179 tm.year, tm.month, tm.monthday, 1180 tm.hour, tm.minute, tm.second); 1181 1182 return buf; 1183} 1184 1185/* reset the global state for unit tests */ 1186void 1187leapsec_ut_pristine(void) 1188{ 1189 memset(_ltab, 0, sizeof(_ltab)); 1190 _lptr = NULL; 1191 _electric = 0; 1192} 1193 1194 1195 1196/* -*- that's all folks! -*- */ 1197