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 27 static 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 */ 35 static inline void* 36 noconst( 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 53 struct 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 }; 59 typedef struct leap_info leap_info_t; 60 61 struct 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 }; 74 typedef struct leap_head leap_head_t; 75 76 struct 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 */ 83 static leap_table_t _ltab[2], *_lptr; 84 static int/*BOOL*/ _electric; 85 86 /* Forward decls of local helpers */ 87 static int add_range(leap_table_t*, const leap_info_t*); 88 static char * get_line(leapsec_reader, void*, char*, size_t); 89 static char * skipws(const char*); 90 static int parsefail(const char * cp, const char * ep); 91 static void reload_limits(leap_table_t*, const vint64*); 92 static void fetch_leap_era(leap_era_t*, const leap_table_t*, 93 const vint64*); 94 static int betweenu32(uint32_t, uint32_t, uint32_t); 95 static void reset_times(leap_table_t*); 96 static int leapsec_add(leap_table_t*, const vint64*, int); 97 static int leapsec_raw(leap_table_t*, const vint64 *, int, int); 98 static const char * lstostr(const vint64 * ts); 99 100 /* ===================================================================== 101 * Get & Set the current leap table 102 */ 103 104 /* ------------------------------------------------------------------ */ 105 leap_table_t * 106 leapsec_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 /* ------------------------------------------------------------------ */ 132 int/*BOOL*/ 133 leapsec_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 /* ------------------------------------------------------------------ */ 142 int/*BOOL*/ 143 leapsec_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 */ 167 void 168 leapsec_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 */ 179 int/*BOOL*/ 180 leapsec_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; 239 240 fail_read: 241 errno = EILSEQ; 242 fail_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 */ 251 void 252 leapsec_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 */ 283 284 int/*BOOL*/ 285 leapsec_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 /* ------------------------------------------------------------------ */ 374 int/*BOOL*/ 375 leapsec_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 /* ------------------------------------------------------------------ */ 390 int/*BOOL*/ 391 leapsec_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 */ 410 void 411 leapsec_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 */ 421 int/*BOOL*/ 422 leapsec_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 /* ------------------------------------------------------------------ */ 496 int/*BOOL*/ 497 leapsec_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 /* ------------------------------------------------------------------ */ 560 void 561 leapsec_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 /* ------------------------------------------------------------------ */ 571 int/*BOOL*/ 572 leapsec_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 /* ------------------------------------------------------------------ */ 585 int32_t 586 leapsec_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 */ 601 int/*BOOL*/ 602 leapsec_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 /* ------------------------------------------------------------------ */ 636 int/*BOOL*/ 637 leapsec_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 /* ------------------------------------------------------------------ */ 652 int/*BOOL*/ 653 leapsec_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 */ 727 static void 728 reset_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 */ 740 static int/*BOOL*/ 741 add_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! Likewise, 747 * assume a positive leap insertion if this is the first entry 748 * in the table. This is not necessarily the best of all ideas, 749 * but it helps a great deal if a system does not have a leap 750 * table and gets updated from an upstream server. 751 */ 752 if (pt->head.size == 0) { 753 pt->head.base_tai = pi->taiof - 1; 754 } else if (pt->head.size >= MAX_HIST) { 755 pt->head.size = MAX_HIST - 1; 756 pt->head.base_tai = pt->info[pt->head.size].taiof; 757 } 758 759 /* make room in lower end and insert item */ 760 memmove(pt->info+1, pt->info, pt->head.size*sizeof(*pt->info)); 761 pt->info[0] = *pi; 762 pt->head.size++; 763 764 /* invalidate the cached limit data -- we might have news ;-) 765 * 766 * This blocks a spurious transition detection. OTOH, if you add 767 * a value after the last query before a leap transition was 768 * expected to occur, this transition trigger is lost. But we 769 * can probably live with that. 770 */ 771 reset_times(pt); 772 return TRUE; 773 } 774 775 /* [internal] given a reader function, read characters into a buffer 776 * until either EOL or EOF is reached. Makes sure that the buffer is 777 * always NUL terminated, but silently truncates excessive data. The 778 * EOL-marker ('\n') is *not* stored in the buffer. 779 * 780 * Returns the pointer to the buffer, unless EOF was reached when trying 781 * to read the first character of a line. 782 */ 783 static char * 784 get_line( 785 leapsec_reader func, 786 void * farg, 787 char * buff, 788 size_t size) 789 { 790 int ch; 791 char *ptr; 792 793 /* if we cannot even store the delimiter, declare failure */ 794 if (buff == NULL || size == 0) 795 return NULL; 796 797 ptr = buff; 798 while (EOF != (ch = (*func)(farg)) && '\n' != ch) 799 if (size > 1) { 800 size--; 801 *ptr++ = (char)ch; 802 } 803 /* discard trailing whitespace */ 804 while (ptr != buff && isspace((u_char)ptr[-1])) 805 ptr--; 806 *ptr = '\0'; 807 return (ptr == buff && ch == EOF) ? NULL : buff; 808 } 809 810 /* [internal] skips whitespace characters from a character buffer. */ 811 static char * 812 skipws( 813 const char *ptr) 814 { 815 while (isspace((u_char)*ptr)) 816 ptr++; 817 return (char*)noconst(ptr); 818 } 819 820 /* [internal] check if a strtoXYZ ended at EOL or whitespace and 821 * converted something at all. Return TRUE if something went wrong. 822 */ 823 static int/*BOOL*/ 824 parsefail( 825 const char * cp, 826 const char * ep) 827 { 828 return (cp == ep) 829 || (*ep && *ep != '#' && !isspace((u_char)*ep)); 830 } 831 832 /* [internal] reload the table limits around the given time stamp. This 833 * is where the real work is done when it comes to table lookup and 834 * evaluation. Some care has been taken to have correct code for dealing 835 * with boundary conditions and empty tables. 836 * 837 * In electric mode, transition and trip time are the same. In dumb 838 * mode, the difference of the TAI offsets must be taken into account 839 * and trip time and transition time become different. The difference 840 * becomes the warping distance when the trip time is reached. 841 */ 842 static void 843 reload_limits( 844 leap_table_t * pt, 845 const vint64 * ts) 846 { 847 int idx; 848 849 /* Get full time and search the true lower bound. Use a 850 * simple loop here, since the number of entries does 851 * not warrant a binary search. This also works for an empty 852 * table, so there is no shortcut for that case. 853 */ 854 for (idx = 0; idx != pt->head.size; idx++) 855 if (ucmpv64(ts, &pt->info[idx].ttime) >= 0) 856 break; 857 858 /* get time limits with proper bound conditions. Note that the 859 * bounds of the table will be observed even if the table is 860 * empty -- no undefined condition must arise from this code. 861 */ 862 if (idx >= pt->head.size) { 863 memset(&pt->head.ebase, 0x00, sizeof(vint64)); 864 pt->head.this_tai = pt->head.base_tai; 865 } else { 866 pt->head.ebase = pt->info[idx].ttime; 867 pt->head.this_tai = pt->info[idx].taiof; 868 } 869 if (--idx >= 0) { 870 pt->head.next_tai = pt->info[idx].taiof; 871 pt->head.dynls = pt->info[idx].dynls; 872 pt->head.ttime = pt->info[idx].ttime; 873 874 if (_electric) 875 pt->head.dtime = pt->head.ttime; 876 else 877 pt->head.dtime = addv64i32( 878 &pt->head.ttime, 879 pt->head.next_tai - pt->head.this_tai); 880 881 pt->head.stime = subv64u32( 882 &pt->head.ttime, pt->info[idx].stime); 883 884 } else { 885 memset(&pt->head.ttime, 0xFF, sizeof(vint64)); 886 pt->head.stime = pt->head.ttime; 887 pt->head.dtime = pt->head.ttime; 888 pt->head.next_tai = pt->head.this_tai; 889 pt->head.dynls = 0; 890 } 891 } 892 893 /* [internal] fetch the leap era for a given time stamp. 894 * This is a cut-down version the algorithm used to reload the table 895 * limits, but it does not update any global state and provides just the 896 * era information for a given time stamp. 897 */ 898 static void 899 fetch_leap_era( 900 leap_era_t * into, 901 const leap_table_t * pt , 902 const vint64 * ts ) 903 { 904 int idx; 905 906 /* Simple search loop, also works with empty table. */ 907 for (idx = 0; idx != pt->head.size; idx++) 908 if (ucmpv64(ts, &pt->info[idx].ttime) >= 0) 909 break; 910 /* fetch era data, keeping an eye on boundary conditions */ 911 if (idx >= pt->head.size) { 912 memset(&into->ebase, 0x00, sizeof(vint64)); 913 into->taiof = pt->head.base_tai; 914 } else { 915 into->ebase = pt->info[idx].ttime; 916 into->taiof = pt->info[idx].taiof; 917 } 918 if (--idx >= 0) 919 into->ttime = pt->info[idx].ttime; 920 else 921 memset(&into->ttime, 0xFF, sizeof(vint64)); 922 } 923 924 /* [internal] Take a time stamp and create a leap second frame for 925 * it. This will schedule a leap second for the beginning of the next 926 * month, midnight UTC. The 'insert' argument tells if a leap second is 927 * added (!=0) or removed (==0). We do not handle multiple inserts 928 * (yet?) 929 * 930 * Returns 1 if the insert worked, 0 otherwise. (It's not possible to 931 * insert a leap second into the current history -- only appending 932 * towards the future is allowed!) 933 */ 934 static int/*BOOL*/ 935 leapsec_add( 936 leap_table_t* pt , 937 const vint64 * now64 , 938 int insert) 939 { 940 vint64 ttime, starttime; 941 struct calendar fts; 942 leap_info_t li; 943 944 /* Check against the table expiration and the latest available 945 * leap entry. Do not permit inserts, only appends, and only if 946 * the extend the table beyond the expiration! 947 */ 948 if ( ucmpv64(now64, &pt->head.expire) < 0 949 || (pt->head.size && ucmpv64(now64, &pt->info[0].ttime) <= 0)) { 950 errno = ERANGE; 951 return FALSE; 952 } 953 954 ntpcal_ntp64_to_date(&fts, now64); 955 /* To guard against dangling leap flags: do not accept leap 956 * second request on the 1st hour of the 1st day of the month. 957 */ 958 if (fts.monthday == 1 && fts.hour == 0) { 959 errno = EINVAL; 960 return FALSE; 961 } 962 963 /* Ok, do the remaining calculations */ 964 fts.monthday = 1; 965 fts.hour = 0; 966 fts.minute = 0; 967 fts.second = 0; 968 starttime = ntpcal_date_to_ntp64(&fts); 969 fts.month++; 970 ttime = ntpcal_date_to_ntp64(&fts); 971 972 li.ttime = ttime; 973 li.stime = ttime.D_s.lo - starttime.D_s.lo; 974 li.taiof = (pt->head.size ? pt->info[0].taiof : pt->head.base_tai) 975 + (insert ? 1 : -1); 976 li.dynls = 1; 977 return add_range(pt, &li); 978 } 979 980 /* [internal] Given a time stamp for a leap insertion (the exact begin 981 * of the new leap era), create new leap frame and put it into the 982 * table. This is the work horse for reading a leap file and getting a 983 * leap second update via authenticated network packet. 984 */ 985 int/*BOOL*/ 986 leapsec_raw( 987 leap_table_t * pt, 988 const vint64 * ttime, 989 int taiof, 990 int dynls) 991 { 992 vint64 starttime; 993 struct calendar fts; 994 leap_info_t li; 995 996 /* Check that we either extend the table or get a duplicate of 997 * the latest entry. The latter is a benevolent overwrite with 998 * identical data and could happen if we get an autokey message 999 * that extends the lifetime of the current leapsecond table. 1000 * Otherwise paranoia rulez! 1001 */ 1002 if (pt->head.size) { 1003 int cmp = ucmpv64(ttime, &pt->info[0].ttime); 1004 if (cmp == 0) 1005 cmp -= (taiof != pt->info[0].taiof); 1006 if (cmp < 0) { 1007 errno = ERANGE; 1008 return FALSE; 1009 } 1010 if (cmp == 0) 1011 return TRUE; 1012 } 1013 1014 ntpcal_ntp64_to_date(&fts, ttime); 1015 /* If this does not match the exact month start, bail out. */ 1016 if (fts.monthday != 1 || fts.hour || fts.minute || fts.second) { 1017 errno = EINVAL; 1018 return FALSE; 1019 } 1020 fts.month--; /* was in range 1..12, no overflow here! */ 1021 starttime = ntpcal_date_to_ntp64(&fts); 1022 li.ttime = *ttime; 1023 li.stime = ttime->D_s.lo - starttime.D_s.lo; 1024 li.taiof = (int16_t)taiof; 1025 li.dynls = (dynls != 0); 1026 return add_range(pt, &li); 1027 } 1028 1029 /* [internal] Do a wrap-around save range inclusion check. 1030 * Returns TRUE if x in [lo,hi[ (intervall open on right side) with full 1031 * handling of an overflow / wrap-around. 1032 */ 1033 static int/*BOOL*/ 1034 betweenu32( 1035 uint32_t lo, 1036 uint32_t x, 1037 uint32_t hi) 1038 { 1039 int rc; 1040 1041 if (lo <= hi) 1042 rc = (lo <= x) && (x < hi); 1043 else 1044 rc = (lo <= x) || (x < hi); 1045 return rc; 1046 } 1047 1048 /* ===================================================================== 1049 * validation stuff 1050 */ 1051 1052 typedef struct { 1053 unsigned char hv[ISC_SHA1_DIGESTLENGTH]; 1054 } sha1_digest; 1055 1056 /* [internal] parse a digest line to get the hash signature 1057 * The NIST code creating the hash writes them out as 5 hex integers 1058 * without leading zeros. This makes reading them back as hex-encoded 1059 * BLOB impossible, because there might be less than 40 hex digits. 1060 * 1061 * The solution is to read the values back as integers, and then do the 1062 * byte twiddle necessary to get it into an array of 20 chars. The 1063 * drawback is that it permits any acceptable number syntax provided by 1064 * 'scanf()' and 'strtoul()', including optional signs and '0x' 1065 * prefixes. 1066 */ 1067 static int/*BOOL*/ 1068 do_leap_hash( 1069 sha1_digest * mac, 1070 char const * cp ) 1071 { 1072 int wi, di, num, len; 1073 unsigned long tmp[5]; 1074 1075 memset(mac, 0, sizeof(*mac)); 1076 num = sscanf(cp, " %lx %lx %lx %lx %lx%n", 1077 &tmp[0], &tmp[1], &tmp[2], &tmp[3], &tmp[4], 1078 &len); 1079 if (num != 5 || cp[len] > ' ') 1080 return FALSE; 1081 1082 /* now do the byte twiddle */ 1083 for (wi=0; wi < 5; ++wi) 1084 for (di=3; di >= 0; --di) { 1085 mac->hv[wi*4 + di] = 1086 (unsigned char)(tmp[wi] & 0x0FF); 1087 tmp[wi] >>= 8; 1088 } 1089 return TRUE; 1090 } 1091 1092 /* [internal] add the digits of a data line to the hash, stopping at the 1093 * next hash ('#') character. 1094 */ 1095 static void 1096 do_hash_data( 1097 isc_sha1_t * mdctx, 1098 char const * cp ) 1099 { 1100 unsigned char text[32]; // must be power of two! 1101 unsigned int tlen = 0; 1102 unsigned char ch; 1103 1104 while ('\0' != (ch = *cp++) && '#' != ch) 1105 if (isdigit(ch)) { 1106 text[tlen++] = ch; 1107 tlen &= (sizeof(text)-1); 1108 if (0 == tlen) 1109 isc_sha1_update( 1110 mdctx, text, sizeof(text)); 1111 } 1112 1113 if (0 < tlen) 1114 isc_sha1_update(mdctx, text, tlen); 1115 } 1116 1117 /* given a reader and a reader arg, calculate and validate the the hash 1118 * signature of a NIST leap second file. 1119 */ 1120 int 1121 leapsec_validate( 1122 leapsec_reader func, 1123 void * farg) 1124 { 1125 isc_sha1_t mdctx; 1126 sha1_digest rdig, ldig; /* remote / local digests */ 1127 char line[50]; 1128 int hlseen = -1; 1129 1130 isc_sha1_init(&mdctx); 1131 while (get_line(func, farg, line, sizeof(line))) { 1132 if (!strncmp(line, "#h", 2)) 1133 hlseen = do_leap_hash(&rdig, line+2); 1134 else if (!strncmp(line, "#@", 2)) 1135 do_hash_data(&mdctx, line+2); 1136 else if (!strncmp(line, "#$", 2)) 1137 do_hash_data(&mdctx, line+2); 1138 else if (isdigit((unsigned char)line[0])) 1139 do_hash_data(&mdctx, line); 1140 } 1141 isc_sha1_final(&mdctx, ldig.hv); 1142 isc_sha1_invalidate(&mdctx); 1143 1144 if (0 > hlseen) 1145 return LSVALID_NOHASH; 1146 if (0 == hlseen) 1147 return LSVALID_BADFORMAT; 1148 if (0 != memcmp(&rdig, &ldig, sizeof(sha1_digest))) 1149 return LSVALID_BADHASH; 1150 return LSVALID_GOODHASH; 1151 } 1152 1153 /* 1154 * lstostr - prettyprint NTP seconds 1155 */ 1156 static const char * 1157 lstostr( 1158 const vint64 * ts) 1159 { 1160 char * buf; 1161 struct calendar tm; 1162 1163 LIB_GETBUF(buf); 1164 1165 if ( ! (ts->d_s.hi >= 0 && ntpcal_ntp64_to_date(&tm, ts) >= 0)) 1166 snprintf(buf, LIB_BUFLENGTH, "%s", "9999-12-31T23:59:59Z"); 1167 else 1168 snprintf(buf, LIB_BUFLENGTH, "%04d-%02d-%02dT%02d:%02d:%02dZ", 1169 tm.year, tm.month, tm.monthday, 1170 tm.hour, tm.minute, tm.second); 1171 1172 return buf; 1173 } 1174 1175 /* reset the global state for unit tests */ 1176 void 1177 leapsec_ut_pristine(void) 1178 { 1179 memset(_ltab, 0, sizeof(_ltab)); 1180 _lptr = NULL; 1181 _electric = 0; 1182 } 1183 1184 1185 1186 /* -*- that's all folks! -*- */ 1187