ntp-4.2.8p15.tar.gz: ntp-4.2.8p15/ntpd/refclock_nmea.c

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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 97 #define NMEA_PROTO_IDLEN 4 /* tag name must be at least 4 chars */ 98 #define NMEA_PROTO_MINLEN 6 /* min chars in sentence, excluding CS */ 99 #define NMEA_PROTO_MAXLEN 80 /* max chars in sentence, excluding CS */ 100 #define NMEA_PROTO_FIELDS 32 /* not official; limit on fields per record */ 101 102 /* 103 * We check the timecode format and decode its contents. We only care 104 * about a few of them, the most important being the $GPRMC format: 105 * 106 * $GPRMC,hhmmss,a,fddmm.xx,n,dddmmm.xx,w,zz.z,yyy.,ddmmyy,dd,v*CC 107 * 108 * mode (0,1,2,3) selects sentence ANY/ALL, RMC, GGA, GLL, ZDA 109 * $GPGLL,3513.8385,S,14900.7851,E,232420.594,A*21 110 * $GPGGA,232420.59,3513.8385,S,14900.7851,E,1,05,3.4,00519,M,,,,*3F 111 * $GPRMC,232418.19,A,3513.8386,S,14900.7853,E,00.0,000.0,121199,12.,E*77 112 * 113 * Defining GPZDA to support Standard Time & Date 114 * sentence. The sentence has the following format 115 * 116 * $--ZDA,HHMMSS.SS,DD,MM,YYYY,TH,TM,*CS<CR><LF> 117 * 118 * Apart from the familiar fields, 119 * 'TH' Time zone Hours 120 * 'TM' Time zone Minutes 121 * 122 * Defining GPZDG to support Accord GPS Clock's custom NMEA 123 * sentence. The sentence has the following format 124 * 125 * $GPZDG,HHMMSS.S,DD,MM,YYYY,AA.BB,V*CS<CR><LF> 126 * 127 * It contains the GPS timestamp valid for next PPS pulse. 128 * Apart from the familiar fields, 129 * 'AA.BB' denotes the signal strength( should be < 05.00 ) 130 * 'V' denotes the GPS sync status : 131 * '0' indicates INVALID time, 132 * '1' indicates accuracy of +/-20 ms 133 * '2' indicates accuracy of +/-100 ns 134 * 135 * Defining PGRMF for Garmin GPS Fix Data 136 * $PGRMF,WN,WS,DATE,TIME,LS,LAT,LAT_DIR,LON,LON_DIR,MODE,FIX,SPD,DIR,PDOP,TDOP 137 * WN -- GPS week number (weeks since 1980-01-06, mod 1024) 138 * WS -- GPS seconds in week 139 * LS -- GPS leap seconds, accumulated ( UTC + LS == GPS ) 140 * FIX -- Fix type: 0=nofix, 1=2D, 2=3D 141 * DATE/TIME are standard date/time strings in UTC time scale 142 * 143 * The GPS time can be used to get the full century for the truncated 144 * date spec. 145 */ 146 147 /* 148 * Definitions 149 */ 150 #define DEVICE "/dev/gps%d" /* GPS serial device */ 151 #define PPSDEV "/dev/gpspps%d" /* PPSAPI device override */ 152 #define SPEED232 B4800 /* uart speed (4800 bps) */ 153 #define PRECISION (-9) /* precision assumed (about 2 ms) */ 154 #define PPS_PRECISION (-20) /* precision assumed (about 1 us) */ 155 #define DATE_HOLD 16 /* seconds to hold on provided GPS date */ 156 #define DATE_HLIM 4 /* when do we take ANY date format */ 157 #define REFID "GPS\0" /* reference id */ 158 #define DESCRIPTION "NMEA GPS Clock" /* who we are */ 159 #ifndef O_NOCTTY 160 #define M_NOCTTY 0 161 #else 162 #define M_NOCTTY O_NOCTTY 163 #endif 164 #ifndef O_NONBLOCK 165 #define M_NONBLOCK 0 166 #else 167 #define M_NONBLOCK O_NONBLOCK 168 #endif 169 #define PPSOPENMODE (O_RDWR | M_NOCTTY | M_NONBLOCK) 170 171 /* NMEA sentence array indexes for those we use */ 172 #define NMEA_GPRMC 0 /* recommended min. nav. */ 173 #define NMEA_GPGGA 1 /* fix and quality */ 174 #define NMEA_GPGLL 2 /* geo. lat/long */ 175 #define NMEA_GPZDA 3 /* date/time */ 176 /* 177 * $GPZDG is a proprietary sentence that violates the spec, by not 178 * using $P and an assigned company identifier to prefix the sentence 179 * identifier. When used with this driver, the system needs to be 180 * isolated from other NTP networks, as it operates in GPS time, not 181 * UTC as is much more common. GPS time is >15 seconds different from 182 * UTC due to not respecting leap seconds since 1970 or so. Other 183 * than the different timebase, $GPZDG is similar to $GPZDA. 184 */ 185 #define NMEA_GPZDG 4 186 #define NMEA_PGRMF 5 187 #define NMEA_PUBX04 6 188 #define NMEA_ARRAY_SIZE (NMEA_PUBX04 + 1) 189 190 /* 191 * Sentence selection mode bits 192 */ 193 #define USE_GPRMC 0x00000001u 194 #define USE_GPGGA 0x00000002u 195 #define USE_GPGLL 0x00000004u 196 #define USE_GPZDA 0x00000008u 197 #define USE_PGRMF 0x00000100u 198 #define USE_PUBX04 0x00000200u 199 200 /* mapping from sentence index to controlling mode bit */ 201 static const u_int32 sentence_mode[NMEA_ARRAY_SIZE] = 202 { 203 USE_GPRMC, 204 USE_GPGGA, 205 USE_GPGLL, 206 USE_GPZDA, 207 USE_GPZDA, 208 USE_PGRMF, 209 USE_PUBX04 210 }; 211 212 /* date formats we support */ 213 enum date_fmt { 214 DATE_1_DDMMYY, /* use 1 field with 2-digit year */ 215 DATE_3_DDMMYYYY /* use 3 fields with 4-digit year */ 216 }; 217 218 /* date type */ 219 enum date_type { 220 DTYP_NONE, 221 DTYP_Y2D, /* 2-digit year */ 222 DTYP_W10B, /* 10-bit week in GPS epoch */ 223 DTYP_Y4D, /* 4-digit (full) year */ 224 DTYP_WEXT /* extended week in GPS epoch */ 225 }; 226 227 /* results for 'field_init()' 228 * 229 * Note: If a checksum is present, the checksum test must pass OK or the 230 * sentence is tagged invalid. 231 */ 232 #define CHECK_EMPTY -1 /* no data */ 233 #define CHECK_INVALID 0 /* not a valid NMEA sentence */ 234 #define CHECK_VALID 1 /* valid but without checksum */ 235 #define CHECK_CSVALID 2 /* valid with checksum OK */ 236 237 /* 238 * Unit control structure 239 */ 240 struct refclock_atom; 241 typedef struct refclock_atom TAtomUnit; 242 typedef struct { 243 # ifdef HAVE_PPSAPI 244 TAtomUnit atom; /* PPSAPI structure */ 245 int ppsapi_fd; /* fd used with PPSAPI */ 246 u_char ppsapi_tried; /* attempt PPSAPI once */ 247 u_char ppsapi_lit; /* time_pps_create() worked */ 248 # endif /* HAVE_PPSAPI */ 249 uint16_t rcvtout; /* one-shot for sample expiration */ 250 u_char ppsapi_gate; /* system is on PPS */ 251 u_char gps_time; /* use GPS time, not UTC */ 252 l_fp last_reftime; /* last processed reference stamp */ 253 TNtpDatum last_gpsdate; /* last processed split date/time */ 254 u_short hold_gpsdate; /* validity ticker for above */ 255 u_short type_gpsdate; /* date info type for above */ 256 /* tally stats, reset each poll cycle */ 257 struct 258 { 259 u_int total; 260 u_int accepted; 261 u_int rejected; /* GPS said not enough signal */ 262 u_int malformed; /* Bad checksum, invalid date or time */ 263 u_int filtered; /* mode bits, not GPZDG, same second */ 264 u_int pps_used; 265 } 266 tally; 267 /* per sentence checksum seen flag */ 268 u_char cksum_type[NMEA_ARRAY_SIZE]; 269 270 /* line assembly buffer (NMEAD support) */ 271 u_short lb_len; 272 char lb_buf[BMAX]; /* assembly buffer */ 273 } nmea_unit; 274 275 /* 276 * helper for faster field access 277 */ 278 typedef struct { 279 char *base; /* buffer base */ 280 char *cptr; /* current field ptr */ 281 int blen; /* buffer length */ 282 int cidx; /* current field index */ 283 } nmea_data; 284 285 /* 286 * Function prototypes 287 */ 288 static int nmea_start (int, struct peer *); 289 static void nmea_shutdown (int, struct peer *); 290 static void nmea_receive (struct recvbuf *); 291 static void nmea_poll (int, struct peer *); 292 static void nmea_procrec (struct peer * const, l_fp); 293 #ifdef HAVE_PPSAPI 294 static double tabsdiffd (l_fp, l_fp); 295 static void nmea_control (int, const struct refclockstat *, 296 struct refclockstat *, struct peer *); 297 #define NMEA_CONTROL nmea_control 298 #else 299 #define NMEA_CONTROL noentry 300 #endif /* HAVE_PPSAPI */ 301 static void nmea_timer (int, struct peer *); 302 303 /* parsing helpers */ 304 static int field_init (nmea_data * data, char * cp, int len); 305 static char * field_parse (nmea_data * data, int fn); 306 static void field_wipe (nmea_data * data, ...); 307 static u_char parse_qual (nmea_data * data, int idx, 308 char tag, int inv); 309 static int parse_time (TCivilDate * jd, l_fp * fofs, 310 nmea_data *, int idx); 311 static int parse_date (TCivilDate * jd, nmea_data *, 312 int idx, enum date_fmt fmt); 313 static int parse_gpsw (TGpsDatum *, nmea_data *, 314 int weekidx, int timeidx, int leapidx); 315 316 static int nmead_open (const char * device); 317 318 /* 319 * If we want the driver to output sentences, too: re-enable the send 320 * support functions by defining NMEA_WRITE_SUPPORT to non-zero... 321 */ 322 #if NMEA_WRITE_SUPPORT 323 324 static void gps_send(int, const char *, struct peer *); 325 # ifdef SYS_WINNT 326 # undef write /* ports/winnt/include/config.h: #define write _write */ 327 extern int async_write(int, const void *, unsigned int); 328 # define write(fd, data, octets) async_write(fd, data, octets) 329 # endif /* SYS_WINNT */ 330 331 #endif /* NMEA_WRITE_SUPPORT */ 332 333 /* 334 * ------------------------------------------------------------------- 335 * Transfer vector 336 * ------------------------------------------------------------------- 337 */ 338 struct refclock refclock_nmea = { 339 nmea_start, /* start up driver */ 340 nmea_shutdown, /* shut down driver */ 341 nmea_poll, /* transmit poll message */ 342 NMEA_CONTROL, /* fudge control */ 343 noentry, /* initialize driver */ 344 noentry, /* buginfo */ 345 nmea_timer /* called once per second */ 346 }; 347 348 349 /* 350 * ------------------------------------------------------------------- 351 * nmea_start - open the GPS devices and initialize data for processing 352 * 353 * return 0 on error, 1 on success. Even on error the peer structures 354 * must be in a state that permits 'nmea_shutdown()' to clean up all 355 * resources, because it will be called immediately to do so. 356 * ------------------------------------------------------------------- 357 */ 358 static int 359 nmea_start( 360 int unit, 361 struct peer * peer 362 ) 363 { 364 struct refclockproc * const pp = peer->procptr; 365 nmea_unit * const up = emalloc_zero(sizeof(*up)); 366 char device[20]; 367 size_t devlen; 368 u_int32 rate; 369 int baudrate; 370 const char * baudtext; 371 372 373 /* Get baudrate choice from mode byte bits 4/5/6 */ 374 rate = (peer->ttl & NMEA_BAUDRATE_MASK) >> NMEA_BAUDRATE_SHIFT; 375 376 switch (rate) { 377 case 0: 378 baudrate = SPEED232; 379 baudtext = "4800"; 380 break; 381 case 1: 382 baudrate = B9600; 383 baudtext = "9600"; 384 break; 385 case 2: 386 baudrate = B19200; 387 baudtext = "19200"; 388 break; 389 case 3: 390 baudrate = B38400; 391 baudtext = "38400"; 392 break; 393 # ifdef B57600 394 case 4: 395 baudrate = B57600; 396 baudtext = "57600"; 397 break; 398 # endif 399 # ifdef B115200 400 case 5: 401 baudrate = B115200; 402 baudtext = "115200"; 403 break; 404 # endif 405 default: 406 baudrate = SPEED232; 407 baudtext = "4800 (fallback)"; 408 break; 409 } 410 411 /* Allocate and initialize unit structure */ 412 pp->unitptr = (caddr_t)up; 413 pp->io.fd = -1; 414 pp->io.clock_recv = nmea_receive; 415 pp->io.srcclock = peer; 416 pp->io.datalen = 0; 417 /* force change detection on first valid message */ 418 memset(&up->last_reftime, 0xFF, sizeof(up->last_reftime)); 419 memset(&up->last_gpsdate, 0x00, sizeof(up->last_gpsdate)); 420 /* force checksum on GPRMC, see below */ 421 up->cksum_type[NMEA_GPRMC] = CHECK_CSVALID; 422 # ifdef HAVE_PPSAPI 423 up->ppsapi_fd = -1; 424 # endif /* HAVE_PPSAPI */ 425 ZERO(up->tally); 426 427 /* Initialize miscellaneous variables */ 428 peer->precision = PRECISION; 429 pp->clockdesc = DESCRIPTION; 430 memcpy(&pp->refid, REFID, 4); 431 432 /* Open serial port. Use CLK line discipline, if available. */ 433 devlen = snprintf(device, sizeof(device), DEVICE, unit); 434 if (devlen >= sizeof(device)) { 435 msyslog(LOG_ERR, "%s clock device name too long", 436 refnumtoa(&peer->srcadr)); 437 return FALSE; /* buffer overflow */ 438 } 439 pp->io.fd = refclock_open(device, baudrate, LDISC_CLK); 440 if (0 >= pp->io.fd) { 441 pp->io.fd = nmead_open(device); 442 if (-1 == pp->io.fd) 443 return FALSE; 444 } 445 LOGIF(CLOCKINFO, (LOG_NOTICE, "%s serial %s open at %s bps", 446 refnumtoa(&peer->srcadr), device, baudtext)); 447 448 /* succeed if this clock can be added */ 449 return io_addclock(&pp->io) != 0; 450 } 451 452 /* 453 * ------------------------------------------------------------------- 454 * nmea_shutdown - shut down a GPS clock 455 * 456 * NOTE this routine is called after nmea_start() returns failure, 457 * as well as during a normal shutdown due to ntpq :config unpeer. 458 * ------------------------------------------------------------------- 459 */ 460 static void 461 nmea_shutdown( 462 int unit, 463 struct peer * peer 464 ) 465 { 466 struct refclockproc * const pp = peer->procptr; 467 nmea_unit * const up = (nmea_unit *)pp->unitptr; 468 469 UNUSED_ARG(unit); 470 471 if (up != NULL) { 472 # ifdef HAVE_PPSAPI 473 if (up->ppsapi_lit) 474 time_pps_destroy(up->atom.handle); 475 if (up->ppsapi_tried && up->ppsapi_fd != pp->io.fd) 476 close(up->ppsapi_fd); 477 # endif 478 free(up); 479 } 480 pp->unitptr = (caddr_t)NULL; 481 if (-1 != pp->io.fd) 482 io_closeclock(&pp->io); 483 pp->io.fd = -1; 484 } 485 486 /* 487 * ------------------------------------------------------------------- 488 * nmea_control - configure fudge params 489 * ------------------------------------------------------------------- 490 */ 491 #ifdef HAVE_PPSAPI 492 static void 493 nmea_control( 494 int unit, 495 const struct refclockstat * in_st, 496 struct refclockstat * out_st, 497 struct peer * peer 498 ) 499 { 500 struct refclockproc * const pp = peer->procptr; 501 nmea_unit * const up = (nmea_unit *)pp->unitptr; 502 503 char device[32]; 504 size_t devlen; 505 506 UNUSED_ARG(in_st); 507 UNUSED_ARG(out_st); 508 509 /* 510 * PPS control 511 * 512 * If /dev/gpspps$UNIT can be opened that will be used for 513 * PPSAPI. Otherwise, the GPS serial device /dev/gps$UNIT 514 * already opened is used for PPSAPI as well. (This might not 515 * work, in which case the PPS API remains unavailable...) 516 */ 517 518 /* Light up the PPSAPI interface if not yet attempted. */ 519 if ((CLK_FLAG1 & pp->sloppyclockflag) && !up->ppsapi_tried) { 520 up->ppsapi_tried = TRUE; 521 devlen = snprintf(device, sizeof(device), PPSDEV, unit); 522 if (devlen < sizeof(device)) { 523 up->ppsapi_fd = open(device, PPSOPENMODE, 524 S_IRUSR | S_IWUSR); 525 } else { 526 up->ppsapi_fd = -1; 527 msyslog(LOG_ERR, "%s PPS device name too long", 528 refnumtoa(&peer->srcadr)); 529 } 530 if (-1 == up->ppsapi_fd) 531 up->ppsapi_fd = pp->io.fd; 532 if (refclock_ppsapi(up->ppsapi_fd, &up->atom)) { 533 /* use the PPS API for our own purposes now. */ 534 up->ppsapi_lit = refclock_params( 535 pp->sloppyclockflag, &up->atom); 536 if (!up->ppsapi_lit) { 537 /* failed to configure, drop PPS unit */ 538 time_pps_destroy(up->atom.handle); 539 msyslog(LOG_WARNING, 540 "%s set PPSAPI params fails", 541 refnumtoa(&peer->srcadr)); 542 } 543 /* note: the PPS I/O handle remains valid until 544 * flag1 is cleared or the clock is shut down. 545 */ 546 } else { 547 msyslog(LOG_WARNING, 548 "%s flag1 1 but PPSAPI fails", 549 refnumtoa(&peer->srcadr)); 550 } 551 } 552 553 /* shut down PPS API if activated */ 554 if ( !(CLK_FLAG1 & pp->sloppyclockflag) && up->ppsapi_tried) { 555 /* shutdown PPS API */ 556 if (up->ppsapi_lit) 557 time_pps_destroy(up->atom.handle); 558 up->atom.handle = 0; 559 /* close/drop PPS fd */ 560 if (up->ppsapi_fd != pp->io.fd) 561 close(up->ppsapi_fd); 562 up->ppsapi_fd = -1; 563 564 /* clear markers and peer items */ 565 up->ppsapi_gate = FALSE; 566 up->ppsapi_lit = FALSE; 567 up->ppsapi_tried = FALSE; 568 569 peer->flags &= ~FLAG_PPS; 570 peer->precision = PRECISION; 571 } 572 } 573 #endif /* HAVE_PPSAPI */ 574 575 /* 576 * ------------------------------------------------------------------- 577 * nmea_timer - called once per second 578 * 579 * Usually 'nmea_receive()' can get a timestamp every second, but at 580 * least one Motorola unit needs prompting each time. Doing so in 581 * 'nmea_poll()' gives only one sample per poll cycle, which actually 582 * defeats the purpose of the median filter. Polling once per second 583 * seems a much better idea. 584 * 585 * Also takes care of sample expiration if the receiver fails to 586 * provide new input data. 587 * ------------------------------------------------------------------- 588 */ 589 static void 590 nmea_timer( 591 int unit, 592 struct peer * peer 593 ) 594 { 595 struct refclockproc * const pp = peer->procptr; 596 nmea_unit * const up = (nmea_unit *)pp->unitptr; 597 598 UNUSED_ARG(unit); 599 600 # if NMEA_WRITE_SUPPORT 601 602 if (-1 != pp->io.fd) /* any mode bits to evaluate here? */ 603 gps_send(pp->io.fd, "$PMOTG,RMC,0000*1D\r\n", peer); 604 605 # endif /* NMEA_WRITE_SUPPORT */ 606 607 /* receive timeout occurred? */ 608 if (up->rcvtout) { 609 --up->rcvtout; 610 } else if (pp->codeproc != pp->coderecv) { 611 /* expire one (the oldest) sample, if any */ 612 refclock_samples_expire(pp, 1); 613 /* reset message assembly buffer */ 614 up->lb_buf[0] = '\0'; 615 up->lb_len = 0; 616 } 617 618 if (up->hold_gpsdate && (--up->hold_gpsdate < DATE_HLIM)) 619 up->type_gpsdate = DTYP_NONE; 620 } 621 622 /* 623 * ------------------------------------------------------------------- 624 * nmea_procrec - receive data from the serial interface 625 * 626 * This is the workhorse for NMEA data evaluation: 627 * 628 * + it checks all NMEA data, and rejects sentences that are not valid 629 * NMEA sentences 630 * + it checks whether a sentence is known and to be used 631 * + it parses the time and date data from the NMEA data string and 632 * augments the missing bits. (century in date, whole date, ...) 633 * + it rejects data that is not from the first accepted sentence in a 634 * burst 635 * + it eventually replaces the receive time with the PPS edge time. 636 * + it feeds the data to the internal processing stages. 637 * 638 * This function assumes a non-empty line in the unit line buffer. 639 * ------------------------------------------------------------------- 640 */ 641 static void 642 nmea_procrec( 643 struct peer * const peer, 644 l_fp rd_timestamp 645 ) 646 { 647 /* declare & init control structure pointers */ 648 struct refclockproc * const pp = peer->procptr; 649 nmea_unit * const up = (nmea_unit*)pp->unitptr; 650 651 /* Use these variables to hold data until we decide its worth keeping */ 652 nmea_data rdata; 653 l_fp rd_reftime; 654 655 /* working stuff */ 656 TCivilDate date; /* to keep & convert the time stamp */ 657 TGpsDatum wgps; /* week time storage */ 658 TNtpDatum dntp; 659 l_fp tofs; /* offset to full-second reftime */ 660 /* results of sentence/date/time parsing */ 661 u_char sentence; /* sentence tag */ 662 int checkres; 663 int warp; /* warp to GPS base date */ 664 char * cp; 665 int rc_date, rc_time; 666 u_short rc_dtyp; 667 # ifdef HAVE_PPSAPI 668 int withpps = 0; 669 # endif /* HAVE_PPSAPI */ 670 671 /* make sure data has defined pristine state */ 672 ZERO(tofs); 673 ZERO(date); 674 ZERO(wgps); 675 ZERO(dntp); 676 677 /* 678 * Read the timecode and timestamp, then initialize field 679 * processing. The <CR><LF> at the NMEA line end is translated 680 * to <LF><LF> by the terminal input routines on most systems, 681 * and this gives us one spurious empty read per record which we 682 * better ignore silently. 683 */ 684 checkres = field_init(&rdata, up->lb_buf, up->lb_len); 685 switch (checkres) { 686 687 case CHECK_INVALID: 688 DPRINTF(1, ("%s invalid data: '%s'\n", 689 refnumtoa(&peer->srcadr), up->lb_buf)); 690 refclock_report(peer, CEVNT_BADREPLY); 691 return; 692 693 case CHECK_EMPTY: 694 return; 695 696 default: 697 DPRINTF(1, ("%s gpsread: %d '%s'\n", 698 refnumtoa(&peer->srcadr), up->lb_len, 699 up->lb_buf)); 700 break; 701 } 702 up->tally.total++; 703 704 /* 705 * --> below this point we have a valid NMEA sentence <-- 706 * 707 * Check sentence name. Skip first 2 chars (talker ID) in most 708 * cases, to allow for $GLGGA and $GPGGA etc. Since the name 709 * field has at least 5 chars we can simply shift the field 710 * start. 711 */ 712 cp = field_parse(&rdata, 0); 713 if (strncmp(cp + 2, "RMC,", 4) == 0) 714 sentence = NMEA_GPRMC; 715 else if (strncmp(cp + 2, "GGA,", 4) == 0) 716 sentence = NMEA_GPGGA; 717 else if (strncmp(cp + 2, "GLL,", 4) == 0) 718 sentence = NMEA_GPGLL; 719 else if (strncmp(cp + 2, "ZDA,", 4) == 0) 720 sentence = NMEA_GPZDA; 721 else if (strncmp(cp + 2, "ZDG,", 4) == 0) 722 sentence = NMEA_GPZDG; 723 else if (strncmp(cp, "PGRMF,", 6) == 0) 724 sentence = NMEA_PGRMF; 725 else if (strncmp(cp, "PUBX,04,", 8) == 0) 726 sentence = NMEA_PUBX04; 727 else 728 return; /* not something we know about */ 729 730 /* Eventually output delay measurement now. */ 731 if (peer->ttl & NMEA_DELAYMEAS_MASK) { 732 mprintf_clock_stats(&peer->srcadr, "delay %0.6f %.*s", 733 ldexp(rd_timestamp.l_uf, -32), 734 (int)(strchr(up->lb_buf, ',') - up->lb_buf), 735 up->lb_buf); 736 } 737 738 /* See if I want to process this message type */ 739 if ((peer->ttl & NMEA_MESSAGE_MASK) && 740 !(peer->ttl & sentence_mode[sentence])) { 741 up->tally.filtered++; 742 return; 743 } 744 745 /* 746 * make sure it came in clean 747 * 748 * Apparently, older NMEA specifications (which are expensive) 749 * did not require the checksum for all sentences. $GPMRC is 750 * the only one so far identified which has always been required 751 * to include a checksum. 752 * 753 * Today, most NMEA GPS receivers checksum every sentence. To 754 * preserve its error-detection capabilities with modern GPSes 755 * while allowing operation without checksums on all but $GPMRC, 756 * we keep track of whether we've ever seen a valid checksum on 757 * a given sentence, and if so, reject future instances without 758 * checksum. ('up->cksum_type[NMEA_GPRMC]' is set in 759 * 'nmea_start()' to enforce checksums for $GPRMC right from the 760 * start.) 761 */ 762 if (up->cksum_type[sentence] <= (u_char)checkres) { 763 up->cksum_type[sentence] = (u_char)checkres; 764 } else { 765 DPRINTF(1, ("%s checksum missing: '%s'\n", 766 refnumtoa(&peer->srcadr), up->lb_buf)); 767 refclock_report(peer, CEVNT_BADREPLY); 768 up->tally.malformed++; 769 return; 770 } 771 772 /* 773 * $GPZDG provides GPS time not UTC, and the two mix poorly. 774 * Once have processed a $GPZDG, do not process any further UTC 775 * sentences (all but $GPZDG currently). 776 */ 777 if (sentence == NMEA_GPZDG) { 778 if (!up->gps_time) { 779 msyslog(LOG_INFO, 780 "%s using GPS time as if it were UTC", 781 refnumtoa(&peer->srcadr)); 782 up->gps_time = 1; 783 } 784 } else { 785 if (up->gps_time) { 786 up->tally.filtered++; 787 return; 788 } 789 } 790 791 DPRINTF(1, ("%s processing %d bytes, timecode '%s'\n", 792 refnumtoa(&peer->srcadr), up->lb_len, up->lb_buf)); 793 794 /* 795 * Grab fields depending on clock string type and possibly wipe 796 * sensitive data from the last timecode. 797 */ 798 rc_date = -1; /* assume we have to do day-time mapping */ 799 rc_dtyp = DTYP_NONE; 800 switch (sentence) { 801 802 case NMEA_GPRMC: 803 /* Check quality byte, fetch data & time */ 804 rc_time = parse_time(&date, &tofs, &rdata, 1); 805 pp->leap = parse_qual(&rdata, 2, 'A', 0); 806 if (up->type_gpsdate <= DTYP_Y2D) { 807 rc_date = parse_date(&date, &rdata, 9, DATE_1_DDMMYY); 808 rc_dtyp = DTYP_Y2D; 809 } 810 if (CLK_FLAG4 & pp->sloppyclockflag) 811 field_wipe(&rdata, 3, 4, 5, 6, -1); 812 break; 813 814 case NMEA_GPGGA: 815 /* Check quality byte, fetch time only */ 816 rc_time = parse_time(&date, &tofs, &rdata, 1); 817 pp->leap = parse_qual(&rdata, 6, '0', 1); 818 if (CLK_FLAG4 & pp->sloppyclockflag) 819 field_wipe(&rdata, 2, 4, -1); 820 break; 821 822 case NMEA_GPGLL: 823 /* Check quality byte, fetch time only */ 824 rc_time = parse_time(&date, &tofs, &rdata, 5); 825 pp->leap = parse_qual(&rdata, 6, 'A', 0); 826 if (CLK_FLAG4 & pp->sloppyclockflag) 827 field_wipe(&rdata, 1, 3, -1); 828 break; 829 830 case NMEA_GPZDA: 831 /* No quality. Assume best, fetch time & full date */ 832 rc_time = parse_time(&date, &tofs, &rdata, 1); 833 if (up->type_gpsdate <= DTYP_Y4D) { 834 rc_date = parse_date(&date, &rdata, 2, DATE_3_DDMMYYYY); 835 rc_dtyp = DTYP_Y4D; 836 } 837 break; 838 839 case NMEA_GPZDG: 840 /* Check quality byte, fetch time & full date */ 841 rc_time = parse_time(&date, &tofs, &rdata, 1); 842 pp->leap = parse_qual(&rdata, 4, '0', 1); 843 --tofs.l_ui; /* GPZDG gives *following* second */ 844 if (up->type_gpsdate <= DTYP_Y4D) { 845 rc_date = parse_date(&date, &rdata, 2, DATE_3_DDMMYYYY); 846 rc_dtyp = DTYP_Y4D; 847 } 848 break; 849 850 case NMEA_PGRMF: 851 /* get time, qualifier and GPS weektime. */ 852 rc_time = parse_time(&date, &tofs, &rdata, 4); 853 if (up->type_gpsdate <= DTYP_W10B) { 854 rc_date = parse_gpsw(&wgps, &rdata, 1, 2, 5); 855 rc_dtyp = DTYP_W10B; 856 } 857 pp->leap = parse_qual(&rdata, 11, '0', 1); 858 if (CLK_FLAG4 & pp->sloppyclockflag) 859 field_wipe(&rdata, 6, 8, -1); 860 break; 861 862 case NMEA_PUBX04: 863 /* PUBX,04 is peculiar. The UTC time-of-week is the *internal* 864 * time base, which is not exactly on par with the fix time. 865 */ 866 rc_time = parse_time(&date, &tofs, &rdata, 2); 867 if (up->type_gpsdate <= DTYP_WEXT) { 868 rc_date = parse_gpsw(&wgps, &rdata, 5, 4, -1); 869 rc_dtyp = DTYP_WEXT; 870 } 871 break; 872 873 default: 874 INVARIANT(0); /* Coverity 97123 */ 875 return; 876 } 877 878 /* check clock sanity; [bug 2143] */ 879 if (pp->leap == LEAP_NOTINSYNC) { /* no good status? */ 880 checkres = CEVNT_PROP; 881 up->tally.rejected++; 882 } 883 /* Check sanity of time-of-day. */ 884 else if (rc_time == 0) { /* no time or conversion error? */ 885 checkres = CEVNT_BADTIME; 886 up->tally.malformed++; 887 } 888 /* Check sanity of date. */ 889 else if (rc_date == 0) { /* no date or conversion error? */ 890 checkres = CEVNT_BADDATE; 891 up->tally.malformed++; 892 } 893 else { 894 checkres = -1; 895 } 896 897 if (checkres != -1) { 898 refclock_save_lcode(pp, up->lb_buf, up->lb_len); 899 refclock_report(peer, checkres); 900 return; 901 } 902 903 /* See if we can augment the receive time stamp. If not, apply 904 * fudge time 2 to the receive time stamp directly. 905 */ 906 # ifdef HAVE_PPSAPI 907 if (up->ppsapi_lit && pp->leap != LEAP_NOTINSYNC) 908 withpps = refclock_ppsaugment( 909 &up->atom, &rd_timestamp, 910 pp->fudgetime2, pp->fudgetime1); 911 else 912 # endif /* HAVE_PPSAPI */ 913 rd_timestamp = ntpfp_with_fudge( 914 rd_timestamp, pp->fudgetime2); 915 916 /* set the GPS base date, if possible */ 917 warp = !(peer->ttl & NMEA_DATETRUST_MASK); 918 if (rc_dtyp != DTYP_NONE) { 919 DPRINTF(1, ("%s saving date, type=%hu\n", 920 refnumtoa(&peer->srcadr), rc_dtyp)); 921 switch (rc_dtyp) { 922 case DTYP_W10B: 923 up->last_gpsdate = gpsntp_from_gpscal_ex( 924 &wgps, (warp = TRUE)); 925 break; 926 case DTYP_WEXT: 927 up->last_gpsdate = gpsntp_from_gpscal_ex( 928 &wgps, warp); 929 break; 930 default: 931 up->last_gpsdate = gpsntp_from_calendar_ex( 932 &date, tofs, warp); 933 break; 934 } 935 up->type_gpsdate = rc_dtyp; 936 up->hold_gpsdate = DATE_HOLD; 937 } 938 /* now convert and possibly extend/expand the time stamp. */ 939 if (up->hold_gpsdate) { /* time of day, based */ 940 dntp = gpsntp_from_daytime2_ex( 941 &date, tofs, &up->last_gpsdate, warp); 942 } else { /* time of day, floating */ 943 dntp = gpsntp_from_daytime1_ex( 944 &date, tofs, rd_timestamp, warp); 945 } 946 947 if (debug) { 948 /* debug print time stamp */ 949 gpsntp_to_calendar(&date, &dntp); 950 # ifdef HAVE_PPSAPI 951 DPRINTF(1, ("%s effective timecode: %s (%s PPS)\n", 952 refnumtoa(&peer->srcadr), 953 ntpcal_iso8601std(NULL, 0, &date), 954 (withpps ? "with" : "without"))); 955 # else /* ?HAVE_PPSAPI */ 956 DPRINTF(1, ("%s effective timecode: %s\n", 957 refnumtoa(&peer->srcadr), 958 ntpcal_iso8601std(NULL, 0, &date))); 959 # endif /* !HAVE_PPSAPI */ 960 } 961 962 /* Get the reference time stamp from the calendar buffer. 963 * Process the new sample in the median filter and determine the 964 * timecode timestamp, but only if the PPS is not in control. 965 * Discard sentence if reference time did not change. 966 */ 967 rd_reftime = ntpfp_from_ntpdatum(&dntp); 968 if (L_ISEQU(&up->last_reftime, &rd_reftime)) { 969 /* Do not touch pp->a_lastcode on purpose! */ 970 up->tally.filtered++; 971 return; 972 } 973 up->last_reftime = rd_reftime; 974 975 DPRINTF(1, ("%s using '%s'\n", 976 refnumtoa(&peer->srcadr), up->lb_buf)); 977 978 /* Data will be accepted. Update stats & log data. */ 979 up->tally.accepted++; 980 refclock_save_lcode(pp, up->lb_buf, up->lb_len); 981 pp->lastrec = rd_timestamp; 982 983 /* If we have PPS augmented receive time, we *must* have a 984 * working PPS source and we must set the flags accordingly. 985 */ 986 # ifdef HAVE_PPSAPI 987 if (withpps) { 988 up->ppsapi_gate = TRUE; 989 peer->precision = PPS_PRECISION; 990 if (tabsdiffd(rd_reftime, rd_timestamp) < 0.5) { 991 if ( ! (peer->ttl & NMEA_QUIETPPS_MASK)) 992 peer->flags |= FLAG_PPS; 993 DPRINTF(2, ("%s PPS_RELATE_PHASE\n", 994 refnumtoa(&peer->srcadr))); 995 up->tally.pps_used++; 996 } else { 997 DPRINTF(2, ("%s PPS_RELATE_EDGE\n", 998 refnumtoa(&peer->srcadr))); 999 } 1000 /* !Note! 'FLAG_PPS' is reset in 'nmea_poll()' */ 1001 } 1002 # endif /* HAVE_PPSAPI */ 1003 /* Whether the receive time stamp is PPS-augmented or not, 1004 * the proper fudge offset is already applied. There's no 1005 * residual fudge to process. 1006 */ 1007 refclock_process_offset(pp, rd_reftime, rd_timestamp, 0.0); 1008 up->rcvtout = 2; 1009 } 1010 1011 /* 1012 * ------------------------------------------------------------------- 1013 * nmea_receive - receive data from the serial interface 1014 * 1015 * With serial IO only, a single call to 'refclock_gtlin()' to get the 1016 * string would suffice to get the NMEA data. When using NMEAD, this 1017 * does unfortunately no longer hold, since TCP is stream oriented and 1018 * not line oriented, and there's no one to do the line-splitting work 1019 * of the TTY driver in line/cooked mode. 1020 * 1021 * So we have to do this manually here, and we have to live with the 1022 * fact that there could be more than one sentence in a receive buffer. 1023 * Likewise, there can be partial messages on either end. (Strictly 1024 * speaking, a receive buffer could also contain just a single fragment, 1025 * though that's unlikely.) 1026 * 1027 * We deal with that by scanning the input buffer, copying bytes from 1028 * the receive buffer to the assembly buffer as we go and calling the 1029 * record processor every time we hit a CR/LF, provided the resulting 1030 * line is not empty. Any leftovers are kept for the next round. 1031 * 1032 * Note: When used with a serial data stream, there's no change to the 1033 * previous line-oriented input: One line is copied to the buffer and 1034 * processed per call. Only with NMEAD the behavior changes, and the 1035 * timing is badly affected unless a PPS channel is also associated with 1036 * the clock instance. TCP leaves us nothing to improve on here. 1037 * ------------------------------------------------------------------- 1038 */ 1039 static void 1040 nmea_receive( 1041 struct recvbuf * rbufp 1042 ) 1043 { 1044 /* declare & init control structure pointers */ 1045 struct peer * const peer = rbufp->recv_peer; 1046 struct refclockproc * const pp = peer->procptr; 1047 nmea_unit * const up = (nmea_unit*)pp->unitptr; 1048 1049 const char *sp, *se; 1050 char *dp, *de; 1051 1052 /* paranoia check: */ 1053 if (up->lb_len >= sizeof(up->lb_buf)) 1054 up->lb_len = 0; 1055 1056 /* pick up last assembly position; leave room for NUL */ 1057 dp = up->lb_buf + up->lb_len; 1058 de = up->lb_buf + sizeof(up->lb_buf) - 1; 1059 /* set up input range */ 1060 sp = (const char *)rbufp->recv_buffer; 1061 se = sp + rbufp->recv_length; 1062 1063 /* walk over the input data, dropping parity bits and control 1064 * chars as we go, and calling the record processor for each 1065 * complete non-empty line. 1066 */ 1067 while (sp != se) { 1068 char ch = (*sp++ & 0x7f); 1069 if (dp == up->lb_buf) { 1070 if (ch == '$') 1071 *dp++ = ch; 1072 } else if (dp > de) { 1073 dp = up->lb_buf; 1074 } else if (ch == '\n' || ch == '\r') { 1075 *dp = '\0'; 1076 up->lb_len = (int)(dp - up->lb_buf); 1077 dp = up->lb_buf; 1078 nmea_procrec(peer, rbufp->recv_time); 1079 } else if (ch >= 0x20 && ch < 0x7f) { 1080 *dp++ = ch; 1081 } 1082 } 1083 /* update state to keep for next round */ 1084 *dp = '\0'; 1085 up->lb_len = (int)(dp - up->lb_buf); 1086 } 1087 1088 /* 1089 * ------------------------------------------------------------------- 1090 * nmea_poll - called by the transmit procedure 1091 * 1092 * Does the necessary bookkeeping stuff to keep the reported state of 1093 * the clock in sync with reality. 1094 * 1095 * We go to great pains to avoid changing state here, since there may 1096 * be more than one eavesdropper receiving the same timecode. 1097 * ------------------------------------------------------------------- 1098 */ 1099 static void 1100 nmea_poll( 1101 int unit, 1102 struct peer * peer 1103 ) 1104 { 1105 struct refclockproc * const pp = peer->procptr; 1106 nmea_unit * const up = (nmea_unit *)pp->unitptr; 1107 1108 /* 1109 * Process median filter samples. If none received, declare a 1110 * timeout and keep going. 1111 */ 1112 # ifdef HAVE_PPSAPI 1113 /* 1114 * If we don't have PPS pulses and time stamps, turn PPS down 1115 * for now. 1116 */ 1117 if (!up->ppsapi_gate) { 1118 peer->flags &= ~FLAG_PPS; 1119 peer->precision = PRECISION; 1120 } else { 1121 up->ppsapi_gate = FALSE; 1122 } 1123 # endif /* HAVE_PPSAPI */ 1124 1125 /* 1126 * If the median filter is empty, claim a timeout. Else process 1127 * the input data and keep the stats going. 1128 */ 1129 if (pp->coderecv == pp->codeproc) { 1130 peer->flags &= ~FLAG_PPS; 1131 if (pp->currentstatus < CEVNT_TIMEOUT) 1132 refclock_report(peer, CEVNT_TIMEOUT); 1133 memset(&up->last_gpsdate, 0, sizeof(up->last_gpsdate)); 1134 } else { 1135 pp->polls++; 1136 pp->lastref = pp->lastrec; 1137 refclock_receive(peer); 1138 if (pp->currentstatus > CEVNT_NOMINAL) 1139 refclock_report(peer, CEVNT_NOMINAL); 1140 } 1141 1142 /* 1143 * If extended logging is required, write the tally stats to the 1144 * clockstats file; otherwise just do a normal clock stats 1145 * record. Clear the tally stats anyway. 1146 */ 1147 if (peer->ttl & NMEA_EXTLOG_MASK) { 1148 /* Log & reset counters with extended logging */ 1149 const char *nmea = pp->a_lastcode; 1150 if (*nmea == '\0') nmea = "(none)"; 1151 mprintf_clock_stats( 1152 &peer->srcadr, "%s %u %u %u %u %u %u", 1153 nmea, 1154 up->tally.total, up->tally.accepted, 1155 up->tally.rejected, up->tally.malformed, 1156 up->tally.filtered, up->tally.pps_used); 1157 } else { 1158 record_clock_stats(&peer->srcadr, pp->a_lastcode); 1159 } 1160 ZERO(up->tally); 1161 } 1162 1163 #if NMEA_WRITE_SUPPORT 1164 /* 1165 * ------------------------------------------------------------------- 1166 * gps_send(fd, cmd, peer) Sends a command to the GPS receiver. 1167 * as in gps_send(fd, "rqts,u", peer); 1168 * 1169 * If 'cmd' starts with a '$' it is assumed that this command is in raw 1170 * format, that is, starts with '$', ends with '<cr><lf>' and that any 1171 * checksum is correctly provided; the command will be send 'as is' in 1172 * that case. Otherwise the function will create the necessary frame 1173 * (start char, chksum, final CRLF) on the fly. 1174 * 1175 * We don't currently send any data, but would like to send RTCM SC104 1176 * messages for differential positioning. It should also give us better 1177 * time. Without a PPS output, we're Just fooling ourselves because of 1178 * the serial code paths 1179 * ------------------------------------------------------------------- 1180 */ 1181 static void 1182 gps_send( 1183 int fd, 1184 const char * cmd, 1185 struct peer * peer 1186 ) 1187 { 1188 /* $...*xy<CR><LF><NUL> add 7 */ 1189 char buf[NMEA_PROTO_MAXLEN + 7]; 1190 int len; 1191 u_char dcs; 1192 const u_char *beg, *end; 1193 1194 if (*cmd != '$') { 1195 /* get checksum and length */ 1196 beg = end = (const u_char*)cmd; 1197 dcs = 0; 1198 while (*end >= ' ' && *end != '*') 1199 dcs ^= *end++; 1200 len = end - beg; 1201 /* format into output buffer with overflow check */ 1202 len = snprintf(buf, sizeof(buf), "$%.*s*%02X\r\n", 1203 len, beg, dcs); 1204 if ((size_t)len >= sizeof(buf)) { 1205 DPRINTF(1, ("%s gps_send: buffer overflow for command '%s'\n", 1206 refnumtoa(&peer->srcadr), cmd)); 1207 return; /* game over player 1 */ 1208 } 1209 cmd = buf; 1210 } else { 1211 len = strlen(cmd); 1212 } 1213 1214 DPRINTF(1, ("%s gps_send: '%.*s'\n", refnumtoa(&peer->srcadr), 1215 len - 2, cmd)); 1216 1217 /* send out the whole stuff */ 1218 if (write(fd, cmd, len) == -1) 1219 refclock_report(peer, CEVNT_FAULT); 1220 } 1221 #endif /* NMEA_WRITE_SUPPORT */ 1222 1223 /* 1224 * ------------------------------------------------------------------- 1225 * helpers for faster field splitting 1226 * ------------------------------------------------------------------- 1227 * 1228 * set up a field record, check syntax and verify checksum 1229 * 1230 * format is $XXXXX,1,2,3,4*ML 1231 * 1232 * 8-bit XOR of characters between $ and * noninclusive is transmitted 1233 * in last two chars M and L holding most and least significant nibbles 1234 * in hex representation such as: 1235 * 1236 * $GPGLL,5057.970,N,00146.110,E,142451,A*27 1237 * $GPVTG,089.0,T,,,15.2,N,,*7F 1238 * 1239 * Some other constraints: 1240 * + The field name must be at least 5 upcase characters or digits and 1241 * must start with a character. 1242 * + The checksum (if present) must be uppercase hex digits. 1243 * + The length of a sentence is limited to 80 characters (not including 1244 * the final CR/LF nor the checksum, but including the leading '$') 1245 * 1246 * Return values: 1247 * + CHECK_INVALID 1248 * The data does not form a valid NMEA sentence or a checksum error 1249 * occurred. 1250 * + CHECK_VALID 1251 * The data is a valid NMEA sentence but contains no checksum. 1252 * + CHECK_CSVALID 1253 * The data is a valid NMEA sentence and passed the checksum test. 1254 * ------------------------------------------------------------------- 1255 */ 1256 static int 1257 field_init( 1258 nmea_data * data, /* context structure */ 1259 char * cptr, /* start of raw data */ 1260 int dlen /* data len, not counting trailing NUL */ 1261 ) 1262 { 1263 u_char cs_l; /* checksum local computed */ 1264 u_char cs_r; /* checksum remote given */ 1265 char * eptr; /* buffer end end pointer */ 1266 char tmp; /* char buffer */ 1267 1268 cs_l = 0; 1269 cs_r = 0; 1270 /* some basic input constraints */ 1271 if (dlen < 0) 1272 dlen = 0; 1273 eptr = cptr + dlen; 1274 *eptr = '\0'; 1275 1276 /* load data context */ 1277 data->base = cptr; 1278 data->cptr = cptr; 1279 data->cidx = 0; 1280 data->blen = dlen; 1281 1282 /* syntax check follows here. check allowed character 1283 * sequences, updating the local computed checksum as we go. 1284 * 1285 * regex equiv: '^\$[A-Z][A-Z0-9]{4,}[^*]*(\*[0-9A-F]{2})?$' 1286 */ 1287 1288 /* -*- start character: '^\$' */ 1289 if (*cptr == '\0') 1290 return CHECK_EMPTY; 1291 if (*cptr++ != '$') 1292 return CHECK_INVALID; 1293 1294 /* -*- advance context beyond start character */ 1295 data->base++; 1296 data->cptr++; 1297 data->blen--; 1298 1299 /* -*- field name: '[A-Z][A-Z0-9]{4,},' */ 1300 if (*cptr < 'A' || *cptr > 'Z') 1301 return CHECK_INVALID; 1302 cs_l ^= *cptr++; 1303 while ((*cptr >= 'A' && *cptr <= 'Z') || 1304 (*cptr >= '0' && *cptr <= '9') ) 1305 cs_l ^= *cptr++; 1306 if (*cptr != ',' || (cptr - data->base) < NMEA_PROTO_IDLEN) 1307 return CHECK_INVALID; 1308 cs_l ^= *cptr++; 1309 1310 /* -*- data: '[^*]*' */ 1311 while (*cptr && *cptr != '*') 1312 cs_l ^= *cptr++; 1313 1314 /* -*- checksum field: (\*[0-9A-F]{2})?$ */ 1315 if (*cptr == '\0') 1316 return CHECK_VALID; 1317 if (*cptr != '*' || cptr != eptr - 3 || 1318 (cptr - data->base) >= NMEA_PROTO_MAXLEN) 1319 return CHECK_INVALID; 1320 1321 for (cptr++; (tmp = *cptr) != '\0'; cptr++) { 1322 if (tmp >= '0' && tmp <= '9') 1323 cs_r = (cs_r << 4) + (tmp - '0'); 1324 else if (tmp >= 'A' && tmp <= 'F') 1325 cs_r = (cs_r << 4) + (tmp - 'A' + 10); 1326 else 1327 break; 1328 } 1329 1330 /* -*- make sure we are at end of string and csum matches */ 1331 if (cptr != eptr || cs_l != cs_r) 1332 return CHECK_INVALID; 1333 1334 return CHECK_CSVALID; 1335 } 1336 1337 /* 1338 * ------------------------------------------------------------------- 1339 * fetch a data field by index, zero being the name field. If this 1340 * function is called repeatedly with increasing indices, the total load 1341 * is O(n), n being the length of the string; if it is called with 1342 * decreasing indices, the total load is O(n^2). Try not to go backwards 1343 * too often. 1344 * ------------------------------------------------------------------- 1345 */ 1346 static char * 1347 field_parse( 1348 nmea_data * data, 1349 int fn 1350 ) 1351 { 1352 char tmp; 1353 1354 if (fn < data->cidx) { 1355 data->cidx = 0; 1356 data->cptr = data->base; 1357 } 1358 while ((fn > data->cidx) && (tmp = *data->cptr) != '\0') { 1359 data->cidx += (tmp == ','); 1360 data->cptr++; 1361 } 1362 return data->cptr; 1363 } 1364 1365 /* 1366 * ------------------------------------------------------------------- 1367 * Wipe (that is, overwrite with '_') data fields and the checksum in 1368 * the last timecode. The list of field indices is given as integers 1369 * in a varargs list, preferably in ascending order, in any case 1370 * terminated by a negative field index. 1371 * 1372 * A maximum number of 8 fields can be overwritten at once to guard 1373 * against runaway (that is, unterminated) argument lists. 1374 * 1375 * This function affects what a remote user can see with 1376 * 1377 * ntpq -c clockvar <server> 1378 * 1379 * Note that this also removes the wiped fields from any clockstats 1380 * log. Some NTP operators monitor their NMEA GPS using the change in 1381 * location in clockstats over time as as a proxy for the quality of 1382 * GPS reception and thereby time reported. 1383 * ------------------------------------------------------------------- 1384 */ 1385 static void 1386 field_wipe( 1387 nmea_data * data, 1388 ... 1389 ) 1390 { 1391 va_list va; /* vararg index list */ 1392 int fcnt; /* safeguard against runaway arglist */ 1393 int fidx; /* field to nuke, or -1 for checksum */ 1394 char * cp; /* overwrite destination */ 1395 1396 fcnt = 8; 1397 cp = NULL; 1398 va_start(va, data); 1399 do { 1400 fidx = va_arg(va, int); 1401 if (fidx >= 0 && fidx <= NMEA_PROTO_FIELDS) { 1402 cp = field_parse(data, fidx); 1403 } else { 1404 cp = data->base + data->blen; 1405 if (data->blen >= 3 && cp[-3] == '*') 1406 cp -= 2; 1407 } 1408 for ( ; '\0' != *cp && '*' != *cp && ',' != *cp; cp++) 1409 if ('.' != *cp) 1410 *cp = '_'; 1411 } while (fcnt-- && fidx >= 0); 1412 va_end(va); 1413 } 1414 1415 /* 1416 * ------------------------------------------------------------------- 1417 * PARSING HELPERS 1418 * ------------------------------------------------------------------- 1419 */ 1420 typedef unsigned char const UCC; 1421 1422 static char const * const s_eof_chars = ",*\r\n"; 1423 1424 static int field_length(UCC *cp, unsigned int nfields) 1425 { 1426 char const * ep = (char const*)cp; 1427 ep = strpbrk(ep, s_eof_chars); 1428 if (ep && nfields) 1429 while (--nfields && ep && *ep == ',') 1430 ep = strpbrk(ep + 1, s_eof_chars); 1431 return (ep) 1432 ? (int)((UCC*)ep - cp) 1433 : (int)strlen((char const*)cp); 1434 } 1435 1436 /* /[,*\r\n]/ --> skip */ 1437 static int _parse_eof(UCC *cp, UCC ** ep) 1438 { 1439 int rc = (strchr(s_eof_chars, *(char const*)cp) != NULL); 1440 *ep = cp + rc; 1441 return rc; 1442 } 1443 1444 /* /,/ --> skip */ 1445 static int _parse_sep(UCC *cp, UCC ** ep) 1446 { 1447 int rc = (*cp == ','); 1448 *ep = cp + rc; 1449 return rc; 1450 } 1451 1452 /* /[[:digit:]]{2}/ --> uint16_t */ 1453 static int _parse_num2d(UCC *cp, UCC ** ep, uint16_t *into) 1454 { 1455 int rc = FALSE; 1456 1457 if (isdigit(cp[0]) && isdigit(cp[1])) { 1458 *into = (cp[0] - '0') * 10 + (cp[1] - '0'); 1459 cp += 2; 1460 rc = TRUE; 1461 } 1462 *ep = cp; 1463 return rc; 1464 } 1465 1466 /* /[[:digit:]]+/ --> uint16_t */ 1467 static int _parse_u16(UCC *cp, UCC **ep, uint16_t *into, unsigned int ndig) 1468 { 1469 uint16_t num = 0; 1470 int rc = FALSE; 1471 if (isdigit(*cp) && ndig) { 1472 rc = TRUE; 1473 do 1474 num = (num * 10) + (*cp - '0'); 1475 while (isdigit(*++cp) && --ndig); 1476 *into = num; 1477 } 1478 *ep = cp; 1479 return rc; 1480 } 1481 1482 /* /[[:digit:]]+/ --> uint32_t */ 1483 static int _parse_u32(UCC *cp, UCC **ep, uint32_t *into, unsigned int ndig) 1484 { 1485 uint32_t num = 0; 1486 int rc = FALSE; 1487 if (isdigit(*cp) && ndig) { 1488 rc = TRUE; 1489 do 1490 num = (num * 10) + (*cp - '0'); 1491 while (isdigit(*++cp) && --ndig); 1492 *into = num; 1493 } 1494 *ep = cp; 1495 return rc; 1496 } 1497 1498 /* /(\.[[:digit:]]*)?/ --> l_fp{0, f} 1499 * read fractional seconds, convert to l_fp 1500 * 1501 * Only the first 9 decimal digits are evaluated; any excess is parsed 1502 * away but silently ignored. (--> truncation to 1 nanosecond) 1503 */ 1504 static int _parse_frac(UCC *cp, UCC **ep, l_fp *into) 1505 { 1506 static const uint32_t powtab[10] = { 1507 0, 1508 100000000, 10000000, 1000000, 1509 100000, 10000, 1000, 1510 100, 10, 1 1511 }; 1512 1513 struct timespec ts; 1514 ZERO(ts); 1515 if (*cp == '.') { 1516 uint32_t fval = 0; 1517 UCC * sp = cp + 1; 1518 if (_parse_u32(sp, &cp, &fval, 9)) 1519 ts.tv_nsec = fval * powtab[(size_t)(cp - sp)]; 1520 while (isdigit(*cp)) 1521 ++cp; 1522 } 1523 1524 *ep = cp; 1525 *into = tspec_intv_to_lfp(ts); 1526 return TRUE; 1527 } 1528 1529 /* /[[:digit:]]{6}/ --> time-of-day 1530 * parses a number string representing 'HHMMSS' 1531 */ 1532 static int _parse_time(UCC *cp, UCC ** ep, TCivilDate *into) 1533 { 1534 uint16_t s, m, h; 1535 int rc; 1536 UCC * xp = cp; 1537 1538 rc = _parse_num2d(cp, &cp, &h) && (h < 24) 1539 && _parse_num2d(cp, &cp, &m) && (m < 60) 1540 && _parse_num2d(cp, &cp, &s) && (s < 61); /* leap seconds! */ 1541 1542 if (rc) { 1543 into->hour = (uint8_t)h; 1544 into->minute = (uint8_t)m; 1545 into->second = (uint8_t)s; 1546 *ep = cp; 1547 } else { 1548 *ep = xp; 1549 DPRINTF(1, ("nmea: invalid time code: '%.*s'\n", 1550 field_length(xp, 1), xp)); 1551 } 1552 return rc; 1553 } 1554 1555 /* /[[:digit:]]{6}/ --> civil date 1556 * parses a number string representing 'ddmmyy' 1557 */ 1558 static int _parse_date1(UCC *cp, UCC **ep, TCivilDate *into) 1559 { 1560 unsigned short d, m, y; 1561 int rc; 1562 UCC * xp = cp; 1563 1564 rc = _parse_num2d(cp, &cp, &d) && (d - 1 < 31) 1565 && _parse_num2d(cp, &cp, &m) && (m - 1 < 12) 1566 && _parse_num2d(cp, &cp, &y) 1567 && _parse_eof(cp, ep); 1568 if (rc) { 1569 into->monthday = (uint8_t )d; 1570 into->month = (uint8_t )m; 1571 into->year = (uint16_t)y; 1572 *ep = cp; 1573 } else { 1574 *ep = xp; 1575 DPRINTF(1, ("nmea: invalid date code: '%.*s'\n", 1576 field_length(xp, 1), xp)); 1577 } 1578 return rc; 1579 } 1580 1581 /* /[[:digit:]]+,[[:digit:]]+,[[:digit:]]+/ --> civil date 1582 * parses three successive numeric fields as date: day,month,year 1583 */ 1584 static int _parse_date3(UCC *cp, UCC **ep, TCivilDate *into) 1585 { 1586 uint16_t d, m, y; 1587 int rc; 1588 UCC * xp = cp; 1589 1590 rc = _parse_u16(cp, &cp, &d, 2) && (d - 1 < 31) 1591 && _parse_sep(cp, &cp) 1592 && _parse_u16(cp, &cp, &m, 2) && (m - 1 < 12) 1593 && _parse_sep(cp, &cp) 1594 && _parse_u16(cp, &cp, &y, 4) && (y > 1980) 1595 && _parse_eof(cp, ep); 1596 if (rc) { 1597 into->monthday = (uint8_t )d; 1598 into->month = (uint8_t )m; 1599 into->year = (uint16_t)y; 1600 *ep = cp; 1601 } else { 1602 *ep = xp; 1603 DPRINTF(1, ("nmea: invalid date code: '%.*s'\n", 1604 field_length(xp, 3), xp)); 1605 } 1606 return rc; 1607 } 1608 1609 /* 1610 * ------------------------------------------------------------------- 1611 * Check sync status 1612 * 1613 * If the character at the data field start matches the tag value, 1614 * return LEAP_NOWARNING and LEAP_NOTINSYNC otherwise. If the 'inverted' 1615 * flag is given, just the opposite value is returned. If there is no 1616 * data field (*cp points to the NUL byte) the result is LEAP_NOTINSYNC. 1617 * ------------------------------------------------------------------- 1618 */ 1619 static u_char 1620 parse_qual( 1621 nmea_data * rd, 1622 int idx, 1623 char tag, 1624 int inv 1625 ) 1626 { 1627 static const u_char table[2] = { 1628 LEAP_NOTINSYNC, LEAP_NOWARNING }; 1629 1630 char * dp = field_parse(rd, idx); 1631 1632 return table[ *dp && ((*dp == tag) == !inv) ]; 1633 } 1634 1635 /* 1636 * ------------------------------------------------------------------- 1637 * Parse a time stamp in HHMMSS[.sss] format with error checking. 1638 * 1639 * returns 1 on success, 0 on failure 1640 * ------------------------------------------------------------------- 1641 */ 1642 static int 1643 parse_time( 1644 struct calendar * jd, /* result calendar pointer */ 1645 l_fp * fofs, /* storage for nsec fraction */ 1646 nmea_data * rd, 1647 int idx 1648 ) 1649 { 1650 UCC * dp = (UCC*)field_parse(rd, idx); 1651 1652 return _parse_time(dp, &dp, jd) 1653 && _parse_frac(dp, &dp, fofs) 1654 && _parse_eof (dp, &dp); 1655 } 1656 1657 /* 1658 * ------------------------------------------------------------------- 1659 * Parse a date string from an NMEA sentence. This could either be a 1660 * partial date in DDMMYY format in one field, or DD,MM,YYYY full date 1661 * spec spanning three fields. This function does some extensive error 1662 * checking to make sure the date string was consistent. 1663 * 1664 * returns 1 on success, 0 on failure 1665 * ------------------------------------------------------------------- 1666 */ 1667 static int 1668 parse_date( 1669 struct calendar * jd, /* result pointer */ 1670 nmea_data * rd, 1671 int idx, 1672 enum date_fmt fmt 1673 ) 1674 { 1675 UCC * dp = (UCC*)field_parse(rd, idx); 1676 1677 switch (fmt) { 1678 case DATE_1_DDMMYY: 1679 return _parse_date1(dp, &dp, jd); 1680 case DATE_3_DDMMYYYY: 1681 return _parse_date3(dp, &dp, jd); 1682 default: 1683 DPRINTF(1, ("nmea: invalid parse format: %d\n", fmt)); 1684 break; 1685 } 1686 return FALSE; 1687 } 1688 1689 /* 1690 * ------------------------------------------------------------------- 1691 * Parse GPS week time info from an NMEA sentence. This info contains 1692 * the GPS week number, the GPS time-of-week and the leap seconds GPS 1693 * to UTC. 1694 * 1695 * returns 1 on success, 0 on failure 1696 * ------------------------------------------------------------------- 1697 */ 1698 static int 1699 parse_gpsw( 1700 TGpsDatum * wd, 1701 nmea_data * rd, 1702 int weekidx, 1703 int timeidx, 1704 int leapidx 1705 ) 1706 { 1707 uint32_t secs; 1708 uint16_t week, leap = 0; 1709 l_fp fofs; 1710 int rc; 1711 1712 UCC * dpw = (UCC*)field_parse(rd, weekidx); 1713 UCC * dps = (UCC*)field_parse(rd, timeidx); 1714 1715 rc = _parse_u16 (dpw, &dpw, &week, 5) 1716 && _parse_eof (dpw, &dpw) 1717 && _parse_u32 (dps, &dps, &secs, 9) 1718 && _parse_frac(dps, &dps, &fofs) 1719 && _parse_eof (dps, &dps) 1720 && (secs < 7*SECSPERDAY); 1721 if (rc && leapidx > 0) { 1722 UCC * dpl = (UCC*)field_parse(rd, leapidx); 1723 rc = _parse_u16 (dpl, &dpl, &leap, 5) 1724 && _parse_eof (dpl, &dpl); 1725 } 1726 if (rc) { 1727 fofs.l_ui -= leap; 1728 *wd = gpscal_from_gpsweek(week, secs, fofs); 1729 } else { 1730 DPRINTF(1, ("nmea: parse_gpsw: invalid weektime spec\n")); 1731 } 1732 return rc; 1733 } 1734 1735 1736 #ifdef HAVE_PPSAPI 1737 static double 1738 tabsdiffd( 1739 l_fp t1, 1740 l_fp t2 1741 ) 1742 { 1743 double dd; 1744 L_SUB(&t1, &t2); 1745 LFPTOD(&t1, dd); 1746 return fabs(dd); 1747 } 1748 #endif /* HAVE_PPSAPI */ 1749 1750 /* 1751 * =================================================================== 1752 * 1753 * NMEAD support 1754 * 1755 * original nmead support added by Jon Miner (cp_n18@yahoo.com) 1756 * 1757 * See http://home.hiwaay.net/~taylorc/gps/nmea-server/ 1758 * for information about nmead 1759 * 1760 * To use this, you need to create a link from /dev/gpsX to 1761 * the server:port where nmead is running. Something like this: 1762 * 1763 * ln -s server:port /dev/gps1 1764 * 1765 * Split into separate function by Juergen Perlinger 1766 * (perlinger-at-ntp-dot-org) 1767 * 1768 * =================================================================== 1769 */ 1770 static int 1771 nmead_open( 1772 const char * device 1773 ) 1774 { 1775 int fd = -1; /* result file descriptor */ 1776 1777 # ifdef HAVE_READLINK 1778 char host[80]; /* link target buffer */ 1779 char * port; /* port name or number */ 1780 int rc; /* result code (several)*/ 1781 int sh; /* socket handle */ 1782 struct addrinfo ai_hint; /* resolution hint */ 1783 struct addrinfo *ai_list; /* resolution result */ 1784 struct addrinfo *ai; /* result scan ptr */ 1785 1786 fd = -1; 1787 1788 /* try to read as link, make sure no overflow occurs */ 1789 rc = readlink(device, host, sizeof(host)); 1790 if ((size_t)rc >= sizeof(host)) 1791 return fd; /* error / overflow / truncation */ 1792 host[rc] = '\0'; /* readlink does not place NUL */ 1793 1794 /* get port */ 1795 port = strchr(host, ':'); 1796 if (!port) 1797 return fd; /* not 'host:port' syntax ? */ 1798 *port++ = '\0'; /* put in separator */ 1799 1800 /* get address infos and try to open socket 1801 * 1802 * This getaddrinfo() is naughty in ntpd's nonblocking main 1803 * thread, but you have to go out of your wary to use this code 1804 * and typically the blocking is at startup where its impact is 1805 * reduced. The same holds for the 'connect()', as it is 1806 * blocking, too... 1807 */ 1808 ZERO(ai_hint); 1809 ai_hint.ai_protocol = IPPROTO_TCP; 1810 ai_hint.ai_socktype = SOCK_STREAM; 1811 if (getaddrinfo(host, port, &ai_hint, &ai_list)) 1812 return fd; 1813 1814 for (ai = ai_list; ai && (fd == -1); ai = ai->ai_next) { 1815 sh = socket(ai->ai_family, ai->ai_socktype, 1816 ai->ai_protocol); 1817 if (INVALID_SOCKET == sh) 1818 continue; 1819 rc = connect(sh, ai->ai_addr, ai->ai_addrlen); 1820 if (-1 != rc) 1821 fd = sh; 1822 else 1823 close(sh); 1824 } 1825 freeaddrinfo(ai_list); 1826 if (fd != -1) 1827 make_socket_nonblocking(fd); 1828 # else 1829 fd = -1; 1830 # endif 1831 1832 return fd; 1833 } 1834 #else 1835 NONEMPTY_TRANSLATION_UNIT 1836 #endif /* REFCLOCK && CLOCK_NMEA */