1/* 2 * refclock_nmea.c - clock driver for an NMEA GPS CLOCK 3 * Michael Petry Jun 20, 1994 4 * based on refclock_heathn.c 5 * 6 * Updated to add support for Accord GPS Clock 7 * Venu Gopal Dec 05, 2007 8 * neo.venu@gmail.com, venugopal_d@pgad.gov.in 9 * 10 * Updated to process 'time1' fudge factor 11 * Venu Gopal May 05, 2008 12 * 13 * Converted to common PPSAPI code, separate PPS fudge time1 14 * from serial timecode fudge time2. 15 * Dave Hart July 1, 2009 16 * hart@ntp.org, davehart@davehart.com 17 */ 18 19#ifdef HAVE_CONFIG_H 20#include <config.h> 21#endif 22 23#include "ntp_types.h" 24 25#if defined(REFCLOCK) && defined(CLOCK_NMEA) 26 27#define NMEA_WRITE_SUPPORT 0 /* no write support at the moment */ 28 29#include <sys/stat.h> 30#include <stdio.h> 31#include <ctype.h> 32#ifdef HAVE_SYS_SOCKET_H 33#include <sys/socket.h> 34#endif 35 36#include "ntpd.h" 37#include "ntp_io.h" 38#include "ntp_unixtime.h" 39#include "ntp_refclock.h" 40#include "ntp_stdlib.h" 41#include "ntp_calgps.h" 42#include "timespecops.h" 43 44#ifdef HAVE_PPSAPI 45# include "ppsapi_timepps.h" 46# include "refclock_atom.h" 47#endif /* HAVE_PPSAPI */ 48 49 50/* 51 * This driver supports NMEA-compatible GPS receivers 52 * 53 * Prototype was refclock_trak.c, Thanks a lot. 54 * 55 * The receiver used spits out the NMEA sentences for boat navigation. 56 * And you thought it was an information superhighway. Try a raging river 57 * filled with rapids and whirlpools that rip away your data and warp time. 58 * 59 * If HAVE_PPSAPI is defined code to use the PPSAPI will be compiled in. 60 * On startup if initialization of the PPSAPI fails, it will fall back 61 * to the "normal" timestamps. 62 * 63 * The PPSAPI part of the driver understands fudge flag2 and flag3. If 64 * flag2 is set, it will use the clear edge of the pulse. If flag3 is 65 * set, kernel hardpps is enabled. 66 * 67 * GPS sentences other than RMC (the default) may be enabled by setting 68 * the relevent bits of 'mode' in the server configuration line 69 * server 127.127.20.x mode X 70 * 71 * bit 0 - enables RMC (1) 72 * bit 1 - enables GGA (2) 73 * bit 2 - enables GLL (4) 74 * bit 3 - enables ZDA (8) - Standard Time & Date 75 * bit 3 - enables ZDG (8) - Accord GPS Clock's custom sentence with GPS time 76 * very close to standard ZDA 77 * 78 * Multiple sentences may be selected except when ZDG/ZDA is selected. 79 * 80 * bit 4/5/6 - selects the baudrate for serial port : 81 * 0 for 4800 (default) 82 * 1 for 9600 83 * 2 for 19200 84 * 3 for 38400 85 * 4 for 57600 86 * 5 for 115200 87 */ 88#define NMEA_MESSAGE_MASK 0x0000FF0FU 89#define NMEA_BAUDRATE_MASK 0x00000070U 90#define NMEA_BAUDRATE_SHIFT 4 91 92#define NMEA_DELAYMEAS_MASK 0x00000080U 93#define NMEA_EXTLOG_MASK 0x00010000U 94#define NMEA_QUIETPPS_MASK 0x00020000U 95#define NMEA_DATETRUST_MASK 0x00040000U 96#define NMEA_IGNSTATUS_MASK 0x00080000U 97 98#define NMEA_PROTO_IDLEN 4 /* tag name must be at least 4 chars */ 99#define NMEA_PROTO_MINLEN 6 /* min chars in sentence, excluding CS */ 100#define NMEA_PROTO_MAXLEN 80 /* max chars in sentence, excluding CS */ 101#define NMEA_PROTO_FIELDS 32 /* not official; limit on fields per record */ 102 103/* 104 * We check the timecode format and decode its contents. We only care 105 * about a few of them, the most important being the $GPRMC format: 106 * 107 * $GPRMC,hhmmss,a,fddmm.xx,n,dddmmm.xx,w,zz.z,yyy.,ddmmyy,dd,v*CC 108 * 109 * mode (0,1,2,3) selects sentence ANY/ALL, RMC, GGA, GLL, ZDA 110 * $GPGLL,3513.8385,S,14900.7851,E,232420.594,A*21 111 * $GPGGA,232420.59,3513.8385,S,14900.7851,E,1,05,3.4,00519,M,,,,*3F 112 * $GPRMC,232418.19,A,3513.8386,S,14900.7853,E,00.0,000.0,121199,12.,E*77 113 * 114 * Defining GPZDA to support Standard Time & Date 115 * sentence. The sentence has the following format 116 * 117 * $--ZDA,HHMMSS.SS,DD,MM,YYYY,TH,TM,*CS<CR><LF> 118 * 119 * Apart from the familiar fields, 120 * 'TH' Time zone Hours 121 * 'TM' Time zone Minutes 122 * 123 * Defining GPZDG to support Accord GPS Clock's custom NMEA 124 * sentence. The sentence has the following format 125 * 126 * $GPZDG,HHMMSS.S,DD,MM,YYYY,AA.BB,V*CS<CR><LF> 127 * 128 * It contains the GPS timestamp valid for next PPS pulse. 129 * Apart from the familiar fields, 130 * 'AA.BB' denotes the signal strength( should be < 05.00 ) 131 * 'V' denotes the GPS sync status : 132 * '0' indicates INVALID time, 133 * '1' indicates accuracy of +/-20 ms 134 * '2' indicates accuracy of +/-100 ns 135 * 136 * Defining PGRMF for Garmin GPS Fix Data 137 * $PGRMF,WN,WS,DATE,TIME,LS,LAT,LAT_DIR,LON,LON_DIR,MODE,FIX,SPD,DIR,PDOP,TDOP 138 * WN -- GPS week number (weeks since 1980-01-06, mod 1024) 139 * WS -- GPS seconds in week 140 * LS -- GPS leap seconds, accumulated ( UTC + LS == GPS ) 141 * FIX -- Fix type: 0=nofix, 1=2D, 2=3D 142 * DATE/TIME are standard date/time strings in UTC time scale 143 * 144 * The GPS time can be used to get the full century for the truncated 145 * date spec. 146 */ 147 148/* 149 * Definitions 150 */ 151#define DEVICE "/dev/gps%d" /* GPS serial device */ 152#define PPSDEV "/dev/gpspps%d" /* PPSAPI device override */ 153#define SPEED232 B4800 /* uart speed (4800 bps) */ 154#define PRECISION (-9) /* precision assumed (about 2 ms) */ 155#define PPS_PRECISION (-20) /* precision assumed (about 1 us) */ 156#define DATE_HOLD 16 /* seconds to hold on provided GPS date */ 157#define DATE_HLIM 4 /* when do we take ANY date format */ 158#define REFID "GPS\0" /* reference id */ 159#define DESCRIPTION "NMEA GPS Clock" /* who we are */ 160#ifndef O_NOCTTY 161#define M_NOCTTY 0 162#else 163#define M_NOCTTY O_NOCTTY 164#endif 165#ifndef O_NONBLOCK 166#define M_NONBLOCK 0 167#else 168#define M_NONBLOCK O_NONBLOCK 169#endif 170#define PPSOPENMODE (O_RDWR | M_NOCTTY | M_NONBLOCK) 171 172/* NMEA sentence array indexes for those we use */ 173#define NMEA_GPRMC 0 /* recommended min. nav. */ 174#define NMEA_GPGGA 1 /* fix and quality */ 175#define NMEA_GPGLL 2 /* geo. lat/long */ 176#define NMEA_GPZDA 3 /* date/time */ 177/* 178 * $GPZDG is a proprietary sentence that violates the spec, by not 179 * using $P and an assigned company identifier to prefix the sentence 180 * identifier. When used with this driver, the system needs to be 181 * isolated from other NTP networks, as it operates in GPS time, not 182 * UTC as is much more common. GPS time is >15 seconds different from 183 * UTC due to not respecting leap seconds since 1970 or so. Other 184 * than the different timebase, $GPZDG is similar to $GPZDA. 185 */ 186#define NMEA_GPZDG 4 187#define NMEA_PGRMF 5 188#define NMEA_PUBX04 6 189#define NMEA_ARRAY_SIZE (NMEA_PUBX04 + 1) 190 191/* 192 * Sentence selection mode bits 193 */ 194#define USE_GPRMC 0x00000001u 195#define USE_GPGGA 0x00000002u 196#define USE_GPGLL 0x00000004u 197#define USE_GPZDA 0x00000008u 198#define USE_PGRMF 0x00000100u 199#define USE_PUBX04 0x00000200u 200 201/* mapping from sentence index to controlling mode bit */ 202static const u_int32 sentence_mode[NMEA_ARRAY_SIZE] = 203{ 204 USE_GPRMC, 205 USE_GPGGA, 206 USE_GPGLL, 207 USE_GPZDA, 208 USE_GPZDA, 209 USE_PGRMF, 210 USE_PUBX04 211}; 212 213/* date formats we support */ 214enum date_fmt { 215 DATE_1_DDMMYY, /* use 1 field with 2-digit year */ 216 DATE_3_DDMMYYYY /* use 3 fields with 4-digit year */ 217}; 218 219/* date type */ 220enum date_type { 221 DTYP_NONE, 222 DTYP_Y2D, /* 2-digit year */ 223 DTYP_W10B, /* 10-bit week in GPS epoch */ 224 DTYP_Y4D, /* 4-digit (full) year */ 225 DTYP_WEXT /* extended week in GPS epoch */ 226}; 227 228/* results for 'field_init()' 229 * 230 * Note: If a checksum is present, the checksum test must pass OK or the 231 * sentence is tagged invalid. 232 */ 233#define CHECK_EMPTY -1 /* no data */ 234#define CHECK_INVALID 0 /* not a valid NMEA sentence */ 235#define CHECK_VALID 1 /* valid but without checksum */ 236#define CHECK_CSVALID 2 /* valid with checksum OK */ 237 238/* 239 * Unit control structure 240 */ 241struct refclock_atom; 242typedef struct refclock_atom TAtomUnit; 243typedef struct { 244# ifdef HAVE_PPSAPI 245 TAtomUnit atom; /* PPSAPI structure */ 246 int ppsapi_fd; /* fd used with PPSAPI */ 247 u_char ppsapi_tried; /* attempt PPSAPI once */ 248 u_char ppsapi_lit; /* time_pps_create() worked */ 249# endif /* HAVE_PPSAPI */ 250 uint16_t rcvtout; /* one-shot for sample expiration */ 251 u_char ppsapi_gate; /* system is on PPS */ 252 u_char gps_time; /* use GPS time, not UTC */ 253 l_fp last_reftime; /* last processed reference stamp */ 254 TNtpDatum last_gpsdate; /* last processed split date/time */ 255 u_short hold_gpsdate; /* validity ticker for above */ 256 u_short type_gpsdate; /* date info type for above */ 257 /* tally stats, reset each poll cycle */ 258 struct 259 { 260 u_int total; 261 u_int accepted; 262 u_int rejected; /* GPS said not enough signal */ 263 u_int malformed; /* Bad checksum, invalid date or time */ 264 u_int filtered; /* mode bits, not GPZDG, same second */ 265 u_int pps_used; 266 } 267 tally; 268 /* per sentence checksum seen flag */ 269 u_char cksum_type[NMEA_ARRAY_SIZE]; 270 271 /* line assembly buffer (NMEAD support) */ 272 u_short lb_len; 273 char lb_buf[BMAX]; /* assembly buffer */ 274} nmea_unit; 275 276/* 277 * helper for faster field access 278 */ 279typedef struct { 280 char *base; /* buffer base */ 281 char *cptr; /* current field ptr */ 282 int blen; /* buffer length */ 283 int cidx; /* current field index */ 284} nmea_data; 285 286/* 287 * Function prototypes 288 */ 289static int nmea_start (int, struct peer *); 290static void nmea_shutdown (int, struct peer *); 291static void nmea_receive (struct recvbuf *); 292static void nmea_poll (int, struct peer *); 293static void nmea_procrec (struct peer * const, l_fp); 294#ifdef HAVE_PPSAPI 295static double tabsdiffd (l_fp, l_fp); 296static void nmea_control (int, const struct refclockstat *, 297 struct refclockstat *, struct peer *); 298#define NMEA_CONTROL nmea_control 299#else 300#define NMEA_CONTROL noentry 301#endif /* HAVE_PPSAPI */ 302static void nmea_timer (int, struct peer *); 303 304/* parsing helpers */ 305static int field_init (nmea_data * data, char * cp, int len); 306static char * field_parse (nmea_data * data, int fn); 307static void field_wipe (nmea_data * data, ...); 308static u_char parse_qual (nmea_data * data, int idx, 309 char tag, int inv); 310static int parse_time (TCivilDate * jd, l_fp * fofs, 311 nmea_data *, int idx); 312static int parse_date (TCivilDate * jd, nmea_data *, 313 int idx, enum date_fmt fmt); 314static int parse_gpsw (TGpsDatum *, nmea_data *, 315 int weekidx, int timeidx, int leapidx); 316 317static int nmead_open (const char * device); 318 319/* 320 * If we want the driver to output sentences, too: re-enable the send 321 * support functions by defining NMEA_WRITE_SUPPORT to non-zero... 322 */ 323#if NMEA_WRITE_SUPPORT 324static void gps_send(int, const char *, struct peer *); 325#endif /* NMEA_WRITE_SUPPORT */ 326 327/* 328 * ------------------------------------------------------------------- 329 * Transfer vector 330 * ------------------------------------------------------------------- 331 */ 332struct refclock refclock_nmea = { 333 nmea_start, /* start up driver */ 334 nmea_shutdown, /* shut down driver */ 335 nmea_poll, /* transmit poll message */ 336 NMEA_CONTROL, /* fudge control */ 337 noentry, /* initialize driver */ 338 noentry, /* buginfo */ 339 nmea_timer /* called once per second */ 340}; 341 342 343/* 344 * ------------------------------------------------------------------- 345 * nmea_start - open the GPS devices and initialize data for processing 346 * 347 * return 0 on error, 1 on success. Even on error the peer structures 348 * must be in a state that permits 'nmea_shutdown()' to clean up all 349 * resources, because it will be called immediately to do so. 350 * ------------------------------------------------------------------- 351 */ 352static int 353nmea_start( 354 int unit, 355 struct peer * peer 356 ) 357{ 358 struct refclockproc * const pp = peer->procptr; 359 nmea_unit * const up = emalloc_zero(sizeof(*up)); 360 char device[20]; 361 size_t devlen; 362 u_int32 rate; 363 int baudrate; 364 365 /* Get baudrate choice from mode byte bits 4/5/6 */ 366 rate = (peer->ttl & NMEA_BAUDRATE_MASK) >> NMEA_BAUDRATE_SHIFT; 367 368 switch (rate) { 369 default: 370 case 0: 371 baudrate = SPEED232; 372 break; 373 case 1: 374 baudrate = B9600; 375 break; 376 case 2: 377 baudrate = B19200; 378 break; 379 case 3: 380 baudrate = B38400; 381 break; 382# ifdef B57600 383 case 4: 384 baudrate = B57600; 385 break; 386# endif 387# ifdef B115200 388 case 5: 389 baudrate = B115200; 390 break; 391# endif 392 } 393 394 /* Allocate and initialize unit structure */ 395 pp->unitptr = (caddr_t)up; 396 pp->io.fd = -1; 397 pp->io.clock_recv = nmea_receive; 398 pp->io.srcclock = peer; 399 pp->io.datalen = 0; 400 /* force change detection on first valid message */ 401 memset(&up->last_reftime, 0xFF, sizeof(up->last_reftime)); 402 memset(&up->last_gpsdate, 0x00, sizeof(up->last_gpsdate)); 403 /* force checksum on GPRMC, see below */ 404 up->cksum_type[NMEA_GPRMC] = CHECK_CSVALID; 405# ifdef HAVE_PPSAPI 406 up->ppsapi_fd = -1; 407# endif /* HAVE_PPSAPI */ 408 ZERO(up->tally); 409 410 /* Initialize miscellaneous variables */ 411 peer->precision = PRECISION; 412 pp->clockdesc = DESCRIPTION; 413 memcpy(&pp->refid, REFID, 4); 414 415 /* Open serial port. Use CLK line discipline, if available. */ 416 devlen = snprintf(device, sizeof(device), DEVICE, unit); 417 if (devlen >= sizeof(device)) { 418 msyslog(LOG_ERR, "%s clock device name too long", 419 refnumtoa(&peer->srcadr)); 420 return FALSE; /* buffer overflow */ 421 } 422 pp->io.fd = refclock_open(&peer->srcadr, device, baudrate, LDISC_CLK); 423 if (0 >= pp->io.fd) { 424 pp->io.fd = nmead_open(device); 425 if (-1 == pp->io.fd) 426 return FALSE; 427 } 428 429 /* succeed if this clock can be added */ 430 return io_addclock(&pp->io) != 0; 431} 432 433/* 434 * ------------------------------------------------------------------- 435 * nmea_shutdown - shut down a GPS clock 436 * 437 * NOTE this routine is called after nmea_start() returns failure, 438 * as well as during a normal shutdown due to ntpq :config unpeer. 439 * ------------------------------------------------------------------- 440 */ 441static void 442nmea_shutdown( 443 int unit, 444 struct peer * peer 445 ) 446{ 447 struct refclockproc * const pp = peer->procptr; 448 nmea_unit * const up = (nmea_unit *)pp->unitptr; 449 450 UNUSED_ARG(unit); 451 452 if (up != NULL) { 453# ifdef HAVE_PPSAPI 454 if (up->ppsapi_lit) 455 time_pps_destroy(up->atom.handle); 456 ppsdev_close(pp->io.fd, up->ppsapi_fd); 457# endif 458 free(up); 459 } 460 pp->unitptr = (caddr_t)NULL; 461 if (-1 != pp->io.fd) 462 io_closeclock(&pp->io); 463 pp->io.fd = -1; 464} 465 466/* 467 * ------------------------------------------------------------------- 468 * nmea_control - configure fudge params 469 * ------------------------------------------------------------------- 470 */ 471#ifdef HAVE_PPSAPI 472static void 473nmea_control( 474 int unit, 475 const struct refclockstat * in_st, 476 struct refclockstat * out_st, 477 struct peer * peer 478 ) 479{ 480 struct refclockproc * const pp = peer->procptr; 481 nmea_unit * const up = (nmea_unit *)pp->unitptr; 482 483 char device[32]; 484 size_t devlen; 485 486 UNUSED_ARG(in_st); 487 UNUSED_ARG(out_st); 488 489 /* 490 * PPS control 491 * 492 * If /dev/gpspps$UNIT can be opened that will be used for 493 * PPSAPI. On Linux, a PPS device mathing the TTY will be 494 * searched for and possibly created on the fly. Otherwise, the 495 * GPS serial device /dev/gps$UNIT already opened is used for 496 * PPSAPI as well. (This might not work, in which case the PPS 497 * API remains unavailable...) 498 */ 499 500 /* Light up the PPSAPI interface if not yet attempted. */ 501 if ((CLK_FLAG1 & pp->sloppyclockflag) && !up->ppsapi_tried) { 502 const char *ppsname = device; 503 up->ppsapi_tried = TRUE; 504 /* get FD for the pps device; might be the tty itself! */ 505 devlen = snprintf(device, sizeof(device), PPSDEV, unit); 506 if (devlen >= sizeof(device)) { 507 msyslog(LOG_ERR, "%s PPS device name too long", 508 refnumtoa(&peer->srcadr)); 509 ppsname = NULL; 510 } 511 up->ppsapi_fd = ppsdev_reopen( 512 &peer->srcadr, 513 pp->io.fd, up->ppsapi_fd, 514 ppsname, PPSOPENMODE, (S_IRUSR|S_IWUSR)); 515 /* note 1: the pps fd might be the same as the tty fd 516 * note 2: the current PPS fd remains valid until 517 * - the clock is shut down 518 * - flag1 is set again after being cleared 519 */ 520 if (refclock_ppsapi(up->ppsapi_fd, &up->atom)) { 521 /* use the PPS API for our own purposes now. */ 522 up->ppsapi_lit = refclock_params( 523 pp->sloppyclockflag, &up->atom); 524 if (!up->ppsapi_lit) { 525 /* failed to configure, drop PPS unit */ 526 time_pps_destroy(up->atom.handle); 527 msyslog(LOG_WARNING, 528 "%s set PPSAPI params fails", 529 refnumtoa(&peer->srcadr)); 530 } 531 } else { 532 msyslog(LOG_WARNING, 533 "%s flag1 1 but PPSAPI fails", 534 refnumtoa(&peer->srcadr)); 535 } 536 } 537 538 /* shut down PPS API if activated */ 539 if ( !(CLK_FLAG1 & pp->sloppyclockflag) && up->ppsapi_tried) { 540 /* shutdown PPS API */ 541 if (up->ppsapi_lit) 542 time_pps_destroy(up->atom.handle); 543 up->atom.handle = 0; 544 /* do !!NOT!! close/drop PPS fd here! */ 545 546 /* clear markers and peer items */ 547 up->ppsapi_gate = FALSE; 548 up->ppsapi_lit = FALSE; 549 up->ppsapi_tried = FALSE; 550 551 peer->flags &= ~FLAG_PPS; 552 peer->precision = PRECISION; 553 } 554} 555#endif /* HAVE_PPSAPI */ 556 557/* 558 * ------------------------------------------------------------------- 559 * nmea_timer - called once per second 560 * 561 * Usually 'nmea_receive()' can get a timestamp every second, but at 562 * least one Motorola unit needs prompting each time. Doing so in 563 * 'nmea_poll()' gives only one sample per poll cycle, which actually 564 * defeats the purpose of the median filter. Polling once per second 565 * seems a much better idea. 566 * 567 * Also takes care of sample expiration if the receiver fails to 568 * provide new input data. 569 * ------------------------------------------------------------------- 570 */ 571static void 572nmea_timer( 573 int unit, 574 struct peer * peer 575 ) 576{ 577 struct refclockproc * const pp = peer->procptr; 578 nmea_unit * const up = (nmea_unit *)pp->unitptr; 579 580 UNUSED_ARG(unit); 581 582# if NMEA_WRITE_SUPPORT 583 584 if (-1 != pp->io.fd) /* any mode bits to evaluate here? */ 585 gps_send(pp->io.fd, "$PMOTG,RMC,0000*1D\r\n", peer); 586 587# endif /* NMEA_WRITE_SUPPORT */ 588 589 /* receive timeout occurred? */ 590 if (up->rcvtout) { 591 --up->rcvtout; 592 } else if (pp->codeproc != pp->coderecv) { 593 /* expire one (the oldest) sample, if any */ 594 refclock_samples_expire(pp, 1); 595 /* reset message assembly buffer */ 596 up->lb_buf[0] = '\0'; 597 up->lb_len = 0; 598 } 599 600 if (up->hold_gpsdate && (--up->hold_gpsdate < DATE_HLIM)) 601 up->type_gpsdate = DTYP_NONE; 602} 603 604/* 605 * ------------------------------------------------------------------- 606 * nmea_procrec - receive data from the serial interface 607 * 608 * This is the workhorse for NMEA data evaluation: 609 * 610 * + it checks all NMEA data, and rejects sentences that are not valid 611 * NMEA sentences 612 * + it checks whether a sentence is known and to be used 613 * + it parses the time and date data from the NMEA data string and 614 * augments the missing bits. (century in date, whole date, ...) 615 * + it rejects data that is not from the first accepted sentence in a 616 * burst 617 * + it eventually replaces the receive time with the PPS edge time. 618 * + it feeds the data to the internal processing stages. 619 * 620 * This function assumes a non-empty line in the unit line buffer. 621 * ------------------------------------------------------------------- 622 */ 623static void 624nmea_procrec( 625 struct peer * const peer, 626 l_fp rd_timestamp 627 ) 628{ 629 /* declare & init control structure pointers */ 630 struct refclockproc * const pp = peer->procptr; 631 nmea_unit * const up = (nmea_unit*)pp->unitptr; 632 633 /* Use these variables to hold data until we decide its worth keeping */ 634 nmea_data rdata; 635 l_fp rd_reftime; 636 637 /* working stuff */ 638 TCivilDate date; /* to keep & convert the time stamp */ 639 TGpsDatum wgps; /* week time storage */ 640 TNtpDatum dntp; 641 l_fp tofs; /* offset to full-second reftime */ 642 /* results of sentence/date/time parsing */ 643 u_char sentence; /* sentence tag */ 644 int checkres; 645 int warp; /* warp to GPS base date */ 646 char * cp; 647 int rc_date, rc_time; 648 u_short rc_dtyp; 649# ifdef HAVE_PPSAPI 650 int withpps = 0; 651# endif /* HAVE_PPSAPI */ 652 653 /* make sure data has defined pristine state */ 654 ZERO(tofs); 655 ZERO(date); 656 ZERO(wgps); 657 ZERO(dntp); 658 659 /* 660 * Read the timecode and timestamp, then initialize field 661 * processing. The <CR><LF> at the NMEA line end is translated 662 * to <LF><LF> by the terminal input routines on most systems, 663 * and this gives us one spurious empty read per record which we 664 * better ignore silently. 665 */ 666 checkres = field_init(&rdata, up->lb_buf, up->lb_len); 667 switch (checkres) { 668 669 case CHECK_INVALID: 670 DPRINTF(1, ("%s invalid data: '%s'\n", 671 refnumtoa(&peer->srcadr), up->lb_buf)); 672 refclock_report(peer, CEVNT_BADREPLY); 673 return; 674 675 case CHECK_EMPTY: 676 return; 677 678 default: 679 DPRINTF(1, ("%s gpsread: %d '%s'\n", 680 refnumtoa(&peer->srcadr), up->lb_len, 681 up->lb_buf)); 682 break; 683 } 684 up->tally.total++; 685 686 /* 687 * --> below this point we have a valid NMEA sentence <-- 688 * 689 * Check sentence name. Skip first 2 chars (talker ID) in most 690 * cases, to allow for $GLGGA and $GPGGA etc. Since the name 691 * field has at least 5 chars we can simply shift the field 692 * start. 693 */ 694 cp = field_parse(&rdata, 0); 695 if (strncmp(cp + 2, "RMC,", 4) == 0) 696 sentence = NMEA_GPRMC; 697 else if (strncmp(cp + 2, "GGA,", 4) == 0) 698 sentence = NMEA_GPGGA; 699 else if (strncmp(cp + 2, "GLL,", 4) == 0) 700 sentence = NMEA_GPGLL; 701 else if (strncmp(cp + 2, "ZDA,", 4) == 0) 702 sentence = NMEA_GPZDA; 703 else if (strncmp(cp + 2, "ZDG,", 4) == 0) 704 sentence = NMEA_GPZDG; 705 else if (strncmp(cp, "PGRMF,", 6) == 0) 706 sentence = NMEA_PGRMF; 707 else if (strncmp(cp, "PUBX,04,", 8) == 0) 708 sentence = NMEA_PUBX04; 709 else 710 return; /* not something we know about */ 711 712 /* Eventually output delay measurement now. */ 713 if (peer->ttl & NMEA_DELAYMEAS_MASK) { 714 mprintf_clock_stats(&peer->srcadr, "delay %0.6f %.*s", 715 ldexp(rd_timestamp.l_uf, -32), 716 (int)(strchr(up->lb_buf, ',') - up->lb_buf), 717 up->lb_buf); 718 } 719 720 /* See if I want to process this message type */ 721 if ((peer->ttl & NMEA_MESSAGE_MASK) && 722 !(peer->ttl & sentence_mode[sentence])) { 723 up->tally.filtered++; 724 return; 725 } 726 727 /* 728 * make sure it came in clean 729 * 730 * Apparently, older NMEA specifications (which are expensive) 731 * did not require the checksum for all sentences. $GPMRC is 732 * the only one so far identified which has always been required 733 * to include a checksum. 734 * 735 * Today, most NMEA GPS receivers checksum every sentence. To 736 * preserve its error-detection capabilities with modern GPSes 737 * while allowing operation without checksums on all but $GPMRC, 738 * we keep track of whether we've ever seen a valid checksum on 739 * a given sentence, and if so, reject future instances without 740 * checksum. ('up->cksum_type[NMEA_GPRMC]' is set in 741 * 'nmea_start()' to enforce checksums for $GPRMC right from the 742 * start.) 743 */ 744 if (up->cksum_type[sentence] <= (u_char)checkres) { 745 up->cksum_type[sentence] = (u_char)checkres; 746 } else { 747 DPRINTF(1, ("%s checksum missing: '%s'\n", 748 refnumtoa(&peer->srcadr), up->lb_buf)); 749 refclock_report(peer, CEVNT_BADREPLY); 750 up->tally.malformed++; 751 return; 752 } 753 754 /* 755 * $GPZDG provides GPS time not UTC, and the two mix poorly. 756 * Once have processed a $GPZDG, do not process any further UTC 757 * sentences (all but $GPZDG currently). 758 */ 759 if (sentence == NMEA_GPZDG) { 760 if (!up->gps_time) { 761 msyslog(LOG_INFO, 762 "%s using GPS time as if it were UTC", 763 refnumtoa(&peer->srcadr)); 764 up->gps_time = 1; 765 } 766 } else { 767 if (up->gps_time) { 768 up->tally.filtered++; 769 return; 770 } 771 } 772 773 DPRINTF(1, ("%s processing %d bytes, timecode '%s'\n", 774 refnumtoa(&peer->srcadr), up->lb_len, up->lb_buf)); 775 776 /* 777 * Grab fields depending on clock string type and possibly wipe 778 * sensitive data from the last timecode. 779 */ 780 rc_date = -1; /* assume we have to do day-time mapping */ 781 rc_dtyp = DTYP_NONE; 782 switch (sentence) { 783 784 case NMEA_GPRMC: 785 /* Check quality byte, fetch data & time */ 786 rc_time = parse_time(&date, &tofs, &rdata, 1); 787 pp->leap = parse_qual(&rdata, 2, 'A', 0); 788 if (up->type_gpsdate <= DTYP_Y2D) { 789 rc_date = parse_date(&date, &rdata, 9, DATE_1_DDMMYY); 790 rc_dtyp = DTYP_Y2D; 791 } 792 if (CLK_FLAG4 & pp->sloppyclockflag) 793 field_wipe(&rdata, 3, 4, 5, 6, -1); 794 break; 795 796 case NMEA_GPGGA: 797 /* Check quality byte, fetch time only */ 798 rc_time = parse_time(&date, &tofs, &rdata, 1); 799 pp->leap = parse_qual(&rdata, 6, '0', 1); 800 if (CLK_FLAG4 & pp->sloppyclockflag) 801 field_wipe(&rdata, 2, 4, -1); 802 break; 803 804 case NMEA_GPGLL: 805 /* Check quality byte, fetch time only */ 806 rc_time = parse_time(&date, &tofs, &rdata, 5); 807 pp->leap = parse_qual(&rdata, 6, 'A', 0); 808 if (CLK_FLAG4 & pp->sloppyclockflag) 809 field_wipe(&rdata, 1, 3, -1); 810 break; 811 812 case NMEA_GPZDA: 813 /* No quality. Assume best, fetch time & full date */ 814 rc_time = parse_time(&date, &tofs, &rdata, 1); 815 if (up->type_gpsdate <= DTYP_Y4D) { 816 rc_date = parse_date(&date, &rdata, 2, DATE_3_DDMMYYYY); 817 rc_dtyp = DTYP_Y4D; 818 } 819 break; 820 821 case NMEA_GPZDG: 822 /* Check quality byte, fetch time & full date */ 823 rc_time = parse_time(&date, &tofs, &rdata, 1); 824 pp->leap = parse_qual(&rdata, 4, '0', 1); 825 --tofs.l_ui; /* GPZDG gives *following* second */ 826 if (up->type_gpsdate <= DTYP_Y4D) { 827 rc_date = parse_date(&date, &rdata, 2, DATE_3_DDMMYYYY); 828 rc_dtyp = DTYP_Y4D; 829 } 830 break; 831 832 case NMEA_PGRMF: 833 /* get time, qualifier and GPS weektime. */ 834 rc_time = parse_time(&date, &tofs, &rdata, 4); 835 if (up->type_gpsdate <= DTYP_W10B) { 836 rc_date = parse_gpsw(&wgps, &rdata, 1, 2, 5); 837 rc_dtyp = DTYP_W10B; 838 } 839 pp->leap = parse_qual(&rdata, 11, '0', 1); 840 if (CLK_FLAG4 & pp->sloppyclockflag) 841 field_wipe(&rdata, 6, 8, -1); 842 break; 843 844 case NMEA_PUBX04: 845 /* PUBX,04 is peculiar. The UTC time-of-week is the *internal* 846 * time base, which is not exactly on par with the fix time. 847 */ 848 rc_time = parse_time(&date, &tofs, &rdata, 2); 849 if (up->type_gpsdate <= DTYP_WEXT) { 850 rc_date = parse_gpsw(&wgps, &rdata, 5, 4, -1); 851 rc_dtyp = DTYP_WEXT; 852 } 853 break; 854 855 default: 856 INVARIANT(0); /* Coverity 97123 */ 857 return; 858 } 859 860 /* ignore receiver status? [bug 3694] */ 861 if (peer->ttl & NMEA_IGNSTATUS_MASK) { /* assume always good? */ 862 pp->leap = LEAP_NOWARNING; 863 } 864 865 /* check clock sanity; [bug 2143] */ 866 if (pp->leap == LEAP_NOTINSYNC) { /* no good status? */ 867 checkres = CEVNT_PROP; 868 up->tally.rejected++; 869 } 870 /* Check sanity of time-of-day. */ 871 else if (rc_time == 0) { /* no time or conversion error? */ 872 checkres = CEVNT_BADTIME; 873 up->tally.malformed++; 874 } 875 /* Check sanity of date. */ 876 else if (rc_date == 0) { /* no date or conversion error? */ 877 checkres = CEVNT_BADDATE; 878 up->tally.malformed++; 879 } 880 else { 881 checkres = -1; 882 } 883 884 if (checkres != -1) { 885 refclock_save_lcode(pp, up->lb_buf, up->lb_len); 886 refclock_report(peer, checkres); 887 return; 888 } 889 890 /* See if we can augment the receive time stamp. If not, apply 891 * fudge time 2 to the receive time stamp directly. 892 */ 893# ifdef HAVE_PPSAPI 894 if (up->ppsapi_lit && pp->leap != LEAP_NOTINSYNC) 895 withpps = refclock_ppsaugment( 896 &up->atom, &rd_timestamp, 897 pp->fudgetime2, pp->fudgetime1); 898 else 899# endif /* HAVE_PPSAPI */ 900 rd_timestamp = ntpfp_with_fudge( 901 rd_timestamp, pp->fudgetime2); 902 903 /* set the GPS base date, if possible */ 904 warp = !(peer->ttl & NMEA_DATETRUST_MASK); 905 if (rc_dtyp != DTYP_NONE) { 906 DPRINTF(1, ("%s saving date, type=%hu\n", 907 refnumtoa(&peer->srcadr), rc_dtyp)); 908 switch (rc_dtyp) { 909 case DTYP_W10B: 910 up->last_gpsdate = gpsntp_from_gpscal_ex( 911 &wgps, (warp = TRUE)); 912 break; 913 case DTYP_WEXT: 914 up->last_gpsdate = gpsntp_from_gpscal_ex( 915 &wgps, warp); 916 break; 917 default: 918 up->last_gpsdate = gpsntp_from_calendar_ex( 919 &date, tofs, warp); 920 break; 921 } 922 up->type_gpsdate = rc_dtyp; 923 up->hold_gpsdate = DATE_HOLD; 924 } 925 /* now convert and possibly extend/expand the time stamp. */ 926 if (up->hold_gpsdate) { /* time of day, based */ 927 dntp = gpsntp_from_daytime2_ex( 928 &date, tofs, &up->last_gpsdate, warp); 929 } else { /* time of day, floating */ 930 dntp = gpsntp_from_daytime1_ex( 931 &date, tofs, rd_timestamp, warp); 932 } 933 934 if (debug) { 935 /* debug print time stamp */ 936 gpsntp_to_calendar(&date, &dntp); 937# ifdef HAVE_PPSAPI 938 DPRINTF(1, ("%s effective timecode: %s (%s PPS)\n", 939 refnumtoa(&peer->srcadr), 940 ntpcal_iso8601std(NULL, 0, &date), 941 (withpps ? "with" : "without"))); 942# else /* ?HAVE_PPSAPI */ 943 DPRINTF(1, ("%s effective timecode: %s\n", 944 refnumtoa(&peer->srcadr), 945 ntpcal_iso8601std(NULL, 0, &date))); 946# endif /* !HAVE_PPSAPI */ 947 } 948 949 /* Get the reference time stamp from the calendar buffer. 950 * Process the new sample in the median filter and determine the 951 * timecode timestamp, but only if the PPS is not in control. 952 * Discard sentence if reference time did not change. 953 */ 954 rd_reftime = ntpfp_from_ntpdatum(&dntp); 955 if (L_ISEQU(&up->last_reftime, &rd_reftime)) { 956 /* Do not touch pp->a_lastcode on purpose! */ 957 up->tally.filtered++; 958 return; 959 } 960 up->last_reftime = rd_reftime; 961 962 DPRINTF(1, ("%s using '%s'\n", 963 refnumtoa(&peer->srcadr), up->lb_buf)); 964 965 /* Data will be accepted. Update stats & log data. */ 966 up->tally.accepted++; 967 refclock_save_lcode(pp, up->lb_buf, up->lb_len); 968 pp->lastrec = rd_timestamp; 969 970 /* If we have PPS augmented receive time, we *must* have a 971 * working PPS source and we must set the flags accordingly. 972 */ 973# ifdef HAVE_PPSAPI 974 if (withpps) { 975 up->ppsapi_gate = TRUE; 976 peer->precision = PPS_PRECISION; 977 if (tabsdiffd(rd_reftime, rd_timestamp) < 0.5) { 978 if ( ! (peer->ttl & NMEA_QUIETPPS_MASK)) 979 peer->flags |= FLAG_PPS; 980 DPRINTF(2, ("%s PPS_RELATE_PHASE\n", 981 refnumtoa(&peer->srcadr))); 982 up->tally.pps_used++; 983 } else { 984 DPRINTF(2, ("%s PPS_RELATE_EDGE\n", 985 refnumtoa(&peer->srcadr))); 986 } 987 /* !Note! 'FLAG_PPS' is reset in 'nmea_poll()' */ 988 } 989# endif /* HAVE_PPSAPI */ 990 /* Whether the receive time stamp is PPS-augmented or not, 991 * the proper fudge offset is already applied. There's no 992 * residual fudge to process. 993 */ 994 refclock_process_offset(pp, rd_reftime, rd_timestamp, 0.0); 995 up->rcvtout = 2; 996} 997 998/* 999 * ------------------------------------------------------------------- 1000 * nmea_receive - receive data from the serial interface 1001 * 1002 * With serial IO only, a single call to 'refclock_gtlin()' to get the 1003 * string would suffice to get the NMEA data. When using NMEAD, this 1004 * does unfortunately no longer hold, since TCP is stream oriented and 1005 * not line oriented, and there's no one to do the line-splitting work 1006 * of the TTY driver in line/cooked mode. 1007 * 1008 * So we have to do this manually here, and we have to live with the 1009 * fact that there could be more than one sentence in a receive buffer. 1010 * Likewise, there can be partial messages on either end. (Strictly 1011 * speaking, a receive buffer could also contain just a single fragment, 1012 * though that's unlikely.) 1013 * 1014 * We deal with that by scanning the input buffer, copying bytes from 1015 * the receive buffer to the assembly buffer as we go and calling the 1016 * record processor every time we hit a CR/LF, provided the resulting 1017 * line is not empty. Any leftovers are kept for the next round. 1018 * 1019 * Note: When used with a serial data stream, there's no change to the 1020 * previous line-oriented input: One line is copied to the buffer and 1021 * processed per call. Only with NMEAD the behavior changes, and the 1022 * timing is badly affected unless a PPS channel is also associated with 1023 * the clock instance. TCP leaves us nothing to improve on here. 1024 * ------------------------------------------------------------------- 1025 */ 1026static void 1027nmea_receive( 1028 struct recvbuf * rbufp 1029 ) 1030{ 1031 /* declare & init control structure pointers */ 1032 struct peer * const peer = rbufp->recv_peer; 1033 struct refclockproc * const pp = peer->procptr; 1034 nmea_unit * const up = (nmea_unit*)pp->unitptr; 1035 1036 const char *sp, *se; 1037 char *dp, *de; 1038 1039 /* paranoia check: */ 1040 if (up->lb_len >= sizeof(up->lb_buf)) 1041 up->lb_len = 0; 1042 1043 /* pick up last assembly position; leave room for NUL */ 1044 dp = up->lb_buf + up->lb_len; 1045 de = up->lb_buf + sizeof(up->lb_buf) - 1; 1046 /* set up input range */ 1047 sp = (const char *)rbufp->recv_buffer; 1048 se = sp + rbufp->recv_length; 1049 1050 /* walk over the input data, dropping parity bits and control 1051 * chars as we go, and calling the record processor for each 1052 * complete non-empty line. 1053 */ 1054 while (sp != se) { 1055 char ch = (*sp++ & 0x7f); 1056 if (dp == up->lb_buf) { 1057 if (ch == '$') 1058 *dp++ = ch; 1059 } else if (dp > de) { 1060 dp = up->lb_buf; 1061 } else if (ch == '\n' || ch == '\r') { 1062 *dp = '\0'; 1063 up->lb_len = (int)(dp - up->lb_buf); 1064 dp = up->lb_buf; 1065 nmea_procrec(peer, rbufp->recv_time); 1066 } else if (ch >= 0x20 && ch < 0x7f) { 1067 *dp++ = ch; 1068 } 1069 } 1070 /* update state to keep for next round */ 1071 *dp = '\0'; 1072 up->lb_len = (int)(dp - up->lb_buf); 1073} 1074 1075/* 1076 * ------------------------------------------------------------------- 1077 * nmea_poll - called by the transmit procedure 1078 * 1079 * Does the necessary bookkeeping stuff to keep the reported state of 1080 * the clock in sync with reality. 1081 * 1082 * We go to great pains to avoid changing state here, since there may 1083 * be more than one eavesdropper receiving the same timecode. 1084 * ------------------------------------------------------------------- 1085 */ 1086static void 1087nmea_poll( 1088 int unit, 1089 struct peer * peer 1090 ) 1091{ 1092 struct refclockproc * const pp = peer->procptr; 1093 nmea_unit * const up = (nmea_unit *)pp->unitptr; 1094 1095 /* 1096 * Process median filter samples. If none received, declare a 1097 * timeout and keep going. 1098 */ 1099# ifdef HAVE_PPSAPI 1100 /* 1101 * If we don't have PPS pulses and time stamps, turn PPS down 1102 * for now. 1103 */ 1104 if (!up->ppsapi_gate) { 1105 peer->flags &= ~FLAG_PPS; 1106 peer->precision = PRECISION; 1107 } else { 1108 up->ppsapi_gate = FALSE; 1109 } 1110# endif /* HAVE_PPSAPI */ 1111 1112 /* 1113 * If the median filter is empty, claim a timeout. Else process 1114 * the input data and keep the stats going. 1115 */ 1116 if (pp->coderecv == pp->codeproc) { 1117 peer->flags &= ~FLAG_PPS; 1118 if (pp->currentstatus < CEVNT_TIMEOUT) 1119 refclock_report(peer, CEVNT_TIMEOUT); 1120 memset(&up->last_gpsdate, 0, sizeof(up->last_gpsdate)); 1121 } else { 1122 pp->polls++; 1123 pp->lastref = pp->lastrec; 1124 refclock_receive(peer); 1125 if (pp->currentstatus > CEVNT_NOMINAL) 1126 refclock_report(peer, CEVNT_NOMINAL); 1127 } 1128 1129 /* 1130 * If extended logging is required, write the tally stats to the 1131 * clockstats file; otherwise just do a normal clock stats 1132 * record. Clear the tally stats anyway. 1133 */ 1134 if (peer->ttl & NMEA_EXTLOG_MASK) { 1135 /* Log & reset counters with extended logging */ 1136 const char *nmea = pp->a_lastcode; 1137 if (*nmea == '\0') nmea = "(none)"; 1138 mprintf_clock_stats( 1139 &peer->srcadr, "%s %u %u %u %u %u %u", 1140 nmea, 1141 up->tally.total, up->tally.accepted, 1142 up->tally.rejected, up->tally.malformed, 1143 up->tally.filtered, up->tally.pps_used); 1144 } else { 1145 record_clock_stats(&peer->srcadr, pp->a_lastcode); 1146 } 1147 ZERO(up->tally); 1148} 1149 1150#if NMEA_WRITE_SUPPORT 1151/* 1152 * ------------------------------------------------------------------- 1153 * gps_send(fd, cmd, peer) Sends a command to the GPS receiver. 1154 * as in gps_send(fd, "rqts,u", peer); 1155 * 1156 * If 'cmd' starts with a '$' it is assumed that this command is in raw 1157 * format, that is, starts with '$', ends with '<cr><lf>' and that any 1158 * checksum is correctly provided; the command will be send 'as is' in 1159 * that case. Otherwise the function will create the necessary frame 1160 * (start char, chksum, final CRLF) on the fly. 1161 * 1162 * We don't currently send any data, but would like to send RTCM SC104 1163 * messages for differential positioning. It should also give us better 1164 * time. Without a PPS output, we're Just fooling ourselves because of 1165 * the serial code paths 1166 * ------------------------------------------------------------------- 1167 */ 1168static void 1169gps_send( 1170 int fd, 1171 const char * cmd, 1172 struct peer * peer 1173 ) 1174{ 1175 /* $...*xy<CR><LF><NUL> add 7 */ 1176 char buf[NMEA_PROTO_MAXLEN + 7]; 1177 int len; 1178 u_char dcs; 1179 const u_char *beg, *end; 1180 1181 if (*cmd != '$') { 1182 /* get checksum and length */ 1183 beg = end = (const u_char*)cmd; 1184 dcs = 0; 1185 while (*end >= ' ' && *end != '*') 1186 dcs ^= *end++; 1187 len = end - beg; 1188 /* format into output buffer with overflow check */ 1189 len = snprintf(buf, sizeof(buf), "$%.*s*%02X\r\n", 1190 len, beg, dcs); 1191 if ((size_t)len >= sizeof(buf)) { 1192 DPRINTF(1, ("%s gps_send: buffer overflow for command '%s'\n", 1193 refnumtoa(&peer->srcadr), cmd)); 1194 return; /* game over player 1 */ 1195 } 1196 cmd = buf; 1197 } else { 1198 len = strlen(cmd); 1199 } 1200 1201 DPRINTF(1, ("%s gps_send: '%.*s'\n", refnumtoa(&peer->srcadr), 1202 len - 2, cmd)); 1203 1204 /* send out the whole stuff */ 1205 if (refclock_fdwrite(peer, fd, cmd, len) != len) 1206 refclock_report(peer, CEVNT_FAULT); 1207} 1208#endif /* NMEA_WRITE_SUPPORT */ 1209 1210/* 1211 * ------------------------------------------------------------------- 1212 * helpers for faster field splitting 1213 * ------------------------------------------------------------------- 1214 * 1215 * set up a field record, check syntax and verify checksum 1216 * 1217 * format is $XXXXX,1,2,3,4*ML 1218 * 1219 * 8-bit XOR of characters between $ and * noninclusive is transmitted 1220 * in last two chars M and L holding most and least significant nibbles 1221 * in hex representation such as: 1222 * 1223 * $GPGLL,5057.970,N,00146.110,E,142451,A*27 1224 * $GPVTG,089.0,T,,,15.2,N,,*7F 1225 * 1226 * Some other constraints: 1227 * + The field name must be at least 5 upcase characters or digits and 1228 * must start with a character. 1229 * + The checksum (if present) must be uppercase hex digits. 1230 * + The length of a sentence is limited to 80 characters (not including 1231 * the final CR/LF nor the checksum, but including the leading '$') 1232 * 1233 * Return values: 1234 * + CHECK_INVALID 1235 * The data does not form a valid NMEA sentence or a checksum error 1236 * occurred. 1237 * + CHECK_VALID 1238 * The data is a valid NMEA sentence but contains no checksum. 1239 * + CHECK_CSVALID 1240 * The data is a valid NMEA sentence and passed the checksum test. 1241 * ------------------------------------------------------------------- 1242 */ 1243static int 1244field_init( 1245 nmea_data * data, /* context structure */ 1246 char * cptr, /* start of raw data */ 1247 int dlen /* data len, not counting trailing NUL */ 1248 ) 1249{ 1250 u_char cs_l; /* checksum local computed */ 1251 u_char cs_r; /* checksum remote given */ 1252 char * eptr; /* buffer end end pointer */ 1253 char tmp; /* char buffer */ 1254 1255 cs_l = 0; 1256 cs_r = 0; 1257 /* some basic input constraints */ 1258 if (dlen < 0) 1259 dlen = 0; 1260 eptr = cptr + dlen; 1261 *eptr = '\0'; 1262 1263 /* load data context */ 1264 data->base = cptr; 1265 data->cptr = cptr; 1266 data->cidx = 0; 1267 data->blen = dlen; 1268 1269 /* syntax check follows here. check allowed character 1270 * sequences, updating the local computed checksum as we go. 1271 * 1272 * regex equiv: '^\$[A-Z][A-Z0-9]{4,}[^*]*(\*[0-9A-F]{2})?$' 1273 */ 1274 1275 /* -*- start character: '^\$' */ 1276 if (*cptr == '\0') 1277 return CHECK_EMPTY; 1278 if (*cptr++ != '$') 1279 return CHECK_INVALID; 1280 1281 /* -*- advance context beyond start character */ 1282 data->base++; 1283 data->cptr++; 1284 data->blen--; 1285 1286 /* -*- field name: '[A-Z][A-Z0-9]{4,},' */ 1287 if (*cptr < 'A' || *cptr > 'Z') 1288 return CHECK_INVALID; 1289 cs_l ^= *cptr++; 1290 while ((*cptr >= 'A' && *cptr <= 'Z') || 1291 (*cptr >= '0' && *cptr <= '9') ) 1292 cs_l ^= *cptr++; 1293 if (*cptr != ',' || (cptr - data->base) < NMEA_PROTO_IDLEN) 1294 return CHECK_INVALID; 1295 cs_l ^= *cptr++; 1296 1297 /* -*- data: '[^*]*' */ 1298 while (*cptr && *cptr != '*') 1299 cs_l ^= *cptr++; 1300 1301 /* -*- checksum field: (\*[0-9A-F]{2})?$ */ 1302 if (*cptr == '\0') 1303 return CHECK_VALID; 1304 if (*cptr != '*' || cptr != eptr - 3 || 1305 (cptr - data->base) >= NMEA_PROTO_MAXLEN) 1306 return CHECK_INVALID; 1307 1308 for (cptr++; (tmp = *cptr) != '\0'; cptr++) { 1309 if (tmp >= '0' && tmp <= '9') 1310 cs_r = (cs_r << 4) + (tmp - '0'); 1311 else if (tmp >= 'A' && tmp <= 'F') 1312 cs_r = (cs_r << 4) + (tmp - 'A' + 10); 1313 else 1314 break; 1315 } 1316 1317 /* -*- make sure we are at end of string and csum matches */ 1318 if (cptr != eptr || cs_l != cs_r) 1319 return CHECK_INVALID; 1320 1321 return CHECK_CSVALID; 1322} 1323 1324/* 1325 * ------------------------------------------------------------------- 1326 * fetch a data field by index, zero being the name field. If this 1327 * function is called repeatedly with increasing indices, the total load 1328 * is O(n), n being the length of the string; if it is called with 1329 * decreasing indices, the total load is O(n^2). Try not to go backwards 1330 * too often. 1331 * ------------------------------------------------------------------- 1332 */ 1333static char * 1334field_parse( 1335 nmea_data * data, 1336 int fn 1337 ) 1338{ 1339 char tmp; 1340 1341 if (fn < data->cidx) { 1342 data->cidx = 0; 1343 data->cptr = data->base; 1344 } 1345 while ((fn > data->cidx) && (tmp = *data->cptr) != '\0') { 1346 data->cidx += (tmp == ','); 1347 data->cptr++; 1348 } 1349 return data->cptr; 1350} 1351 1352/* 1353 * ------------------------------------------------------------------- 1354 * Wipe (that is, overwrite with '_') data fields and the checksum in 1355 * the last timecode. The list of field indices is given as integers 1356 * in a varargs list, preferably in ascending order, in any case 1357 * terminated by a negative field index. 1358 * 1359 * A maximum number of 8 fields can be overwritten at once to guard 1360 * against runaway (that is, unterminated) argument lists. 1361 * 1362 * This function affects what a remote user can see with 1363 * 1364 * ntpq -c clockvar <server> 1365 * 1366 * Note that this also removes the wiped fields from any clockstats 1367 * log. Some NTP operators monitor their NMEA GPS using the change in 1368 * location in clockstats over time as as a proxy for the quality of 1369 * GPS reception and thereby time reported. 1370 * ------------------------------------------------------------------- 1371 */ 1372static void 1373field_wipe( 1374 nmea_data * data, 1375 ... 1376 ) 1377{ 1378 va_list va; /* vararg index list */ 1379 int fcnt; /* safeguard against runaway arglist */ 1380 int fidx; /* field to nuke, or -1 for checksum */ 1381 char * cp; /* overwrite destination */ 1382 1383 fcnt = 8; 1384 cp = NULL; 1385 va_start(va, data); 1386 do { 1387 fidx = va_arg(va, int); 1388 if (fidx >= 0 && fidx <= NMEA_PROTO_FIELDS) { 1389 cp = field_parse(data, fidx); 1390 } else { 1391 cp = data->base + data->blen; 1392 if (data->blen >= 3 && cp[-3] == '*') 1393 cp -= 2; 1394 } 1395 for ( ; '\0' != *cp && '*' != *cp && ',' != *cp; cp++) 1396 if ('.' != *cp) 1397 *cp = '_'; 1398 } while (fcnt-- && fidx >= 0); 1399 va_end(va); 1400} 1401 1402/* 1403 * ------------------------------------------------------------------- 1404 * PARSING HELPERS 1405 * ------------------------------------------------------------------- 1406 */ 1407typedef unsigned char const UCC; 1408 1409static char const * const s_eof_chars = ",*\r\n"; 1410 1411#ifdef DEBUG 1412static int field_length(UCC *cp, unsigned int nfields) 1413{ 1414 char const * ep = (char const*)cp; 1415 ep = strpbrk(ep, s_eof_chars); 1416 if (ep && nfields) 1417 while (--nfields && ep && *ep == ',') 1418 ep = strpbrk(ep + 1, s_eof_chars); 1419 return (ep) 1420 ? (int)((UCC*)ep - cp) 1421 : (int)strlen((char const*)cp); 1422} 1423#endif /* DEBUG */ 1424 1425/* /[,*\r\n]/ --> skip */ 1426static int _parse_eof(UCC *cp, UCC ** ep) 1427{ 1428 int rc = (strchr(s_eof_chars, *(char const*)cp) != NULL); 1429 *ep = cp + rc; 1430 return rc; 1431} 1432 1433/* /,/ --> skip */ 1434static int _parse_sep(UCC *cp, UCC ** ep) 1435{ 1436 int rc = (*cp == ','); 1437 *ep = cp + rc; 1438 return rc; 1439} 1440 1441/* /[[:digit:]]{2}/ --> uint16_t */ 1442static int _parse_num2d(UCC *cp, UCC ** ep, uint16_t *into) 1443{ 1444 int rc = FALSE; 1445 1446 if (isdigit(cp[0]) && isdigit(cp[1])) { 1447 *into = (cp[0] - '0') * 10 + (cp[1] - '0'); 1448 cp += 2; 1449 rc = TRUE; 1450 } 1451 *ep = cp; 1452 return rc; 1453} 1454 1455/* /[[:digit:]]+/ --> uint16_t */ 1456static int _parse_u16(UCC *cp, UCC **ep, uint16_t *into, unsigned int ndig) 1457{ 1458 uint16_t num = 0; 1459 int rc = FALSE; 1460 if (isdigit(*cp) && ndig) { 1461 rc = TRUE; 1462 do 1463 num = (num * 10) + (*cp - '0'); 1464 while (isdigit(*++cp) && --ndig); 1465 *into = num; 1466 } 1467 *ep = cp; 1468 return rc; 1469} 1470 1471/* /[[:digit:]]+/ --> uint32_t */ 1472static int _parse_u32(UCC *cp, UCC **ep, uint32_t *into, unsigned int ndig) 1473{ 1474 uint32_t num = 0; 1475 int rc = FALSE; 1476 if (isdigit(*cp) && ndig) { 1477 rc = TRUE; 1478 do 1479 num = (num * 10) + (*cp - '0'); 1480 while (isdigit(*++cp) && --ndig); 1481 *into = num; 1482 } 1483 *ep = cp; 1484 return rc; 1485} 1486 1487/* /(\.[[:digit:]]*)?/ --> l_fp{0, f} 1488 * read fractional seconds, convert to l_fp 1489 * 1490 * Only the first 9 decimal digits are evaluated; any excess is parsed 1491 * away but silently ignored. (--> truncation to 1 nanosecond) 1492 */ 1493static int _parse_frac(UCC *cp, UCC **ep, l_fp *into) 1494{ 1495 static const uint32_t powtab[10] = { 1496 0, 1497 100000000, 10000000, 1000000, 1498 100000, 10000, 1000, 1499 100, 10, 1 1500 }; 1501 1502 struct timespec ts; 1503 ZERO(ts); 1504 if (*cp == '.') { 1505 uint32_t fval = 0; 1506 UCC * sp = cp + 1; 1507 if (_parse_u32(sp, &cp, &fval, 9)) 1508 ts.tv_nsec = fval * powtab[(size_t)(cp - sp)]; 1509 while (isdigit(*cp)) 1510 ++cp; 1511 } 1512 1513 *ep = cp; 1514 *into = tspec_intv_to_lfp(ts); 1515 return TRUE; 1516} 1517 1518/* /[[:digit:]]{6}/ --> time-of-day 1519 * parses a number string representing 'HHMMSS' 1520 */ 1521static int _parse_time(UCC *cp, UCC ** ep, TCivilDate *into) 1522{ 1523 uint16_t s, m, h; 1524 int rc; 1525 UCC * xp = cp; 1526 1527 rc = _parse_num2d(cp, &cp, &h) && (h < 24) 1528 && _parse_num2d(cp, &cp, &m) && (m < 60) 1529 && _parse_num2d(cp, &cp, &s) && (s < 61); /* leap seconds! */ 1530 1531 if (rc) { 1532 into->hour = (uint8_t)h; 1533 into->minute = (uint8_t)m; 1534 into->second = (uint8_t)s; 1535 *ep = cp; 1536 } else { 1537 *ep = xp; 1538 DPRINTF(1, ("nmea: invalid time code: '%.*s'\n", 1539 field_length(xp, 1), xp)); 1540 } 1541 return rc; 1542} 1543 1544/* /[[:digit:]]{6}/ --> civil date 1545 * parses a number string representing 'ddmmyy' 1546 */ 1547static int _parse_date1(UCC *cp, UCC **ep, TCivilDate *into) 1548{ 1549 unsigned short d, m, y; 1550 int rc; 1551 UCC * xp = cp; 1552 1553 rc = _parse_num2d(cp, &cp, &d) && (d - 1 < 31) 1554 && _parse_num2d(cp, &cp, &m) && (m - 1 < 12) 1555 && _parse_num2d(cp, &cp, &y) 1556 && _parse_eof(cp, ep); 1557 if (rc) { 1558 into->monthday = (uint8_t )d; 1559 into->month = (uint8_t )m; 1560 into->year = (uint16_t)y; 1561 *ep = cp; 1562 } else { 1563 *ep = xp; 1564 DPRINTF(1, ("nmea: invalid date code: '%.*s'\n", 1565 field_length(xp, 1), xp)); 1566 } 1567 return rc; 1568} 1569 1570/* /[[:digit:]]+,[[:digit:]]+,[[:digit:]]+/ --> civil date 1571 * parses three successive numeric fields as date: day,month,year 1572 */ 1573static int _parse_date3(UCC *cp, UCC **ep, TCivilDate *into) 1574{ 1575 uint16_t d, m, y; 1576 int rc; 1577 UCC * xp = cp; 1578 1579 rc = _parse_u16(cp, &cp, &d, 2) && (d - 1 < 31) 1580 && _parse_sep(cp, &cp) 1581 && _parse_u16(cp, &cp, &m, 2) && (m - 1 < 12) 1582 && _parse_sep(cp, &cp) 1583 && _parse_u16(cp, &cp, &y, 4) && (y > 1980) 1584 && _parse_eof(cp, ep); 1585 if (rc) { 1586 into->monthday = (uint8_t )d; 1587 into->month = (uint8_t )m; 1588 into->year = (uint16_t)y; 1589 *ep = cp; 1590 } else { 1591 *ep = xp; 1592 DPRINTF(1, ("nmea: invalid date code: '%.*s'\n", 1593 field_length(xp, 3), xp)); 1594 } 1595 return rc; 1596} 1597 1598/* 1599 * ------------------------------------------------------------------- 1600 * Check sync status 1601 * 1602 * If the character at the data field start matches the tag value, 1603 * return LEAP_NOWARNING and LEAP_NOTINSYNC otherwise. If the 'inverted' 1604 * flag is given, just the opposite value is returned. If there is no 1605 * data field (*cp points to the NUL byte) the result is LEAP_NOTINSYNC. 1606 * ------------------------------------------------------------------- 1607 */ 1608static u_char 1609parse_qual( 1610 nmea_data * rd, 1611 int idx, 1612 char tag, 1613 int inv 1614 ) 1615{ 1616 static const u_char table[2] = { 1617 LEAP_NOTINSYNC, LEAP_NOWARNING }; 1618 1619 char * dp = field_parse(rd, idx); 1620 1621 return table[ *dp && ((*dp == tag) == !inv) ]; 1622} 1623 1624/* 1625 * ------------------------------------------------------------------- 1626 * Parse a time stamp in HHMMSS[.sss] format with error checking. 1627 * 1628 * returns 1 on success, 0 on failure 1629 * ------------------------------------------------------------------- 1630 */ 1631static int 1632parse_time( 1633 struct calendar * jd, /* result calendar pointer */ 1634 l_fp * fofs, /* storage for nsec fraction */ 1635 nmea_data * rd, 1636 int idx 1637 ) 1638{ 1639 UCC * dp = (UCC*)field_parse(rd, idx); 1640 1641 return _parse_time(dp, &dp, jd) 1642 && _parse_frac(dp, &dp, fofs) 1643 && _parse_eof (dp, &dp); 1644} 1645 1646/* 1647 * ------------------------------------------------------------------- 1648 * Parse a date string from an NMEA sentence. This could either be a 1649 * partial date in DDMMYY format in one field, or DD,MM,YYYY full date 1650 * spec spanning three fields. This function does some extensive error 1651 * checking to make sure the date string was consistent. 1652 * 1653 * returns 1 on success, 0 on failure 1654 * ------------------------------------------------------------------- 1655 */ 1656static int 1657parse_date( 1658 struct calendar * jd, /* result pointer */ 1659 nmea_data * rd, 1660 int idx, 1661 enum date_fmt fmt 1662 ) 1663{ 1664 UCC * dp = (UCC*)field_parse(rd, idx); 1665 1666 switch (fmt) { 1667 case DATE_1_DDMMYY: 1668 return _parse_date1(dp, &dp, jd); 1669 case DATE_3_DDMMYYYY: 1670 return _parse_date3(dp, &dp, jd); 1671 default: 1672 DPRINTF(1, ("nmea: invalid parse format: %d\n", fmt)); 1673 break; 1674 } 1675 return FALSE; 1676} 1677 1678/* 1679 * ------------------------------------------------------------------- 1680 * Parse GPS week time info from an NMEA sentence. This info contains 1681 * the GPS week number, the GPS time-of-week and the leap seconds GPS 1682 * to UTC. 1683 * 1684 * returns 1 on success, 0 on failure 1685 * ------------------------------------------------------------------- 1686 */ 1687static int 1688parse_gpsw( 1689 TGpsDatum * wd, 1690 nmea_data * rd, 1691 int weekidx, 1692 int timeidx, 1693 int leapidx 1694 ) 1695{ 1696 uint32_t secs; 1697 uint16_t week, leap = 0; 1698 l_fp fofs; 1699 int rc; 1700 1701 UCC * dpw = (UCC*)field_parse(rd, weekidx); 1702 UCC * dps = (UCC*)field_parse(rd, timeidx); 1703 1704 rc = _parse_u16 (dpw, &dpw, &week, 5) 1705 && _parse_eof (dpw, &dpw) 1706 && _parse_u32 (dps, &dps, &secs, 9) 1707 && _parse_frac(dps, &dps, &fofs) 1708 && _parse_eof (dps, &dps) 1709 && (secs < 7*SECSPERDAY); 1710 if (rc && leapidx > 0) { 1711 UCC * dpl = (UCC*)field_parse(rd, leapidx); 1712 rc = _parse_u16 (dpl, &dpl, &leap, 5) 1713 && _parse_eof (dpl, &dpl); 1714 } 1715 if (rc) { 1716 fofs.l_ui -= leap; 1717 *wd = gpscal_from_gpsweek(week, secs, fofs); 1718 } else { 1719 DPRINTF(1, ("nmea: parse_gpsw: invalid weektime spec\n")); 1720 } 1721 return rc; 1722} 1723 1724 1725#ifdef HAVE_PPSAPI 1726static double 1727tabsdiffd( 1728 l_fp t1, 1729 l_fp t2 1730 ) 1731{ 1732 double dd; 1733 L_SUB(&t1, &t2); 1734 LFPTOD(&t1, dd); 1735 return fabs(dd); 1736} 1737#endif /* HAVE_PPSAPI */ 1738 1739/* 1740 * =================================================================== 1741 * 1742 * NMEAD support 1743 * 1744 * original nmead support added by Jon Miner (cp_n18@yahoo.com) 1745 * 1746 * See http://home.hiwaay.net/~taylorc/gps/nmea-server/ 1747 * for information about nmead 1748 * 1749 * To use this, you need to create a link from /dev/gpsX to 1750 * the server:port where nmead is running. Something like this: 1751 * 1752 * ln -s server:port /dev/gps1 1753 * 1754 * Split into separate function by Juergen Perlinger 1755 * (perlinger-at-ntp-dot-org) 1756 * 1757 * =================================================================== 1758 */ 1759static int 1760nmead_open( 1761 const char * device 1762 ) 1763{ 1764 int fd = -1; /* result file descriptor */ 1765 1766# ifdef HAVE_READLINK 1767 char host[80]; /* link target buffer */ 1768 char * port; /* port name or number */ 1769 int rc; /* result code (several)*/ 1770 int sh; /* socket handle */ 1771 struct addrinfo ai_hint; /* resolution hint */ 1772 struct addrinfo *ai_list; /* resolution result */ 1773 struct addrinfo *ai; /* result scan ptr */ 1774 1775 fd = -1; 1776 1777 /* try to read as link, make sure no overflow occurs */ 1778 rc = readlink(device, host, sizeof(host)); 1779 if ((size_t)rc >= sizeof(host)) 1780 return fd; /* error / overflow / truncation */ 1781 host[rc] = '\0'; /* readlink does not place NUL */ 1782 1783 /* get port */ 1784 port = strchr(host, ':'); 1785 if (!port) 1786 return fd; /* not 'host:port' syntax ? */ 1787 *port++ = '\0'; /* put in separator */ 1788 1789 /* get address infos and try to open socket 1790 * 1791 * This getaddrinfo() is naughty in ntpd's nonblocking main 1792 * thread, but you have to go out of your wary to use this code 1793 * and typically the blocking is at startup where its impact is 1794 * reduced. The same holds for the 'connect()', as it is 1795 * blocking, too... 1796 */ 1797 ZERO(ai_hint); 1798 ai_hint.ai_protocol = IPPROTO_TCP; 1799 ai_hint.ai_socktype = SOCK_STREAM; 1800 if (getaddrinfo(host, port, &ai_hint, &ai_list)) 1801 return fd; 1802 1803 for (ai = ai_list; ai && (fd == -1); ai = ai->ai_next) { 1804 sh = socket(ai->ai_family, ai->ai_socktype, 1805 ai->ai_protocol); 1806 if (INVALID_SOCKET == sh) 1807 continue; 1808 rc = connect(sh, ai->ai_addr, ai->ai_addrlen); 1809 if (-1 != rc) 1810 fd = sh; 1811 else 1812 close(sh); 1813 } 1814 freeaddrinfo(ai_list); 1815 if (fd != -1) 1816 make_socket_nonblocking(fd); 1817# else 1818 fd = -1; 1819# endif 1820 1821 return fd; 1822} 1823#else 1824NONEMPTY_TRANSLATION_UNIT 1825#endif /* REFCLOCK && CLOCK_NMEA */ 1826