gnss-sdr/src/core/libs/supl/supl.c

/*
** SUPL library with some RRLP
**
** Copyright (c) 2007 Tatu Mannisto <tatu a-t tajuma d-o-t com>
** All rights reserved.
** Redistribution and modifications are permitted subject to BSD license.
**
*/

#include <stdio.h>
#include <fcntl.h>
#include <netdb.h>
#include <errno.h>
#include <time.h>
#include <unistd.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <sys/time.h>
#include <openssl/crypto.h>
#include <openssl/x509.h>
#include <openssl/pem.h>
#include <openssl/ssl.h>
#include <openssl/err.h>

#include "ULP-PDU.h"
#include "PDU.h"

#include "supl.h"

#define PARAM_GSM_CELL_CURRENT 1
#define PARAM_GSM_CELL_KNOWN 2
#define PARAM_WCDMA_CELL_CURRENT 4

#define OPTIONAL_MISSING ((void*)0)

#ifdef SUPL_DEBUG
static struct supl_debug_s {
  FILE *log;
  int verbose_rrlp, verbose_supl, debug;
  int sent,recv, out_msg, in_msg;
} debug;
#endif

static int server_connect(char *server);
static int pdu_make_ulp_start(supl_ctx_t *ctx, supl_ulp_t *pdu);
static int pdu_make_ulp_pos_init(supl_ctx_t *ctx, supl_ulp_t *pdu);
static int pdu_make_ulp_rrlp_ack(supl_ctx_t *ctx, supl_ulp_t *pdu, PDU_t *rrlp);
static int supl_more_rrlp(PDU_t *rrlp);
static int supl_response_harvest(supl_ctx_t *ctx, supl_ulp_t *pdu);

int EXPORT supl_ulp_decode(supl_ulp_t *pdu) {
  ULP_PDU_t *ulp;
  asn_codec_ctx_t ctx;
  asn_dec_rval_t rval;

  ulp = calloc(1, sizeof(ULP_PDU_t));
  pdu->pdu = ulp;

  ctx.max_stack_size = 0;
  rval = uper_decode_complete(&ctx, &asn_DEF_ULP_PDU, (void **)&ulp, pdu->buffer, pdu->size);
  if (rval.code == RC_OK) {
    return 0;
  }

  free(ulp);
  pdu->pdu = 0;

  return E_SUPL_DECODE;
}

int EXPORT supl_ulp_encode(supl_ulp_t *pdu) {
  asn_enc_rval_t ret;
  int pdu_len;

  ret = uper_encode_to_buffer(&asn_DEF_ULP_PDU, pdu->pdu, pdu->buffer, sizeof(pdu->buffer));
  if (ret.encoded != -1) {
    memset(pdu->buffer, 0, sizeof(pdu->buffer));

    pdu_len = (ret.encoded + 7) >> 3;
    ((ULP_PDU_t *)pdu->pdu)->length = pdu_len;

    ret = uper_encode_to_buffer(&asn_DEF_ULP_PDU, pdu->pdu, pdu->buffer, sizeof(pdu->buffer));
    if (ret.encoded > 0) {
      int len = (ret.encoded + 7) >> 3;

      if (len == pdu_len) {
	pdu->size = pdu_len;
	return 0;
      }
    }
  }

  return E_SUPL_ENCODE;
}

void EXPORT supl_ulp_free(supl_ulp_t *pdu) {
  asn_DEF_ULP_PDU.free_struct(&asn_DEF_ULP_PDU, pdu->pdu, 0);
}

int EXPORT supl_ulp_send(supl_ctx_t *ctx, supl_ulp_t *pdu) {
  int err;

#if SUPL_DEBUG
  if (debug.verbose_supl) {
    fprintf(debug.log, "Send %lu bytes\n", pdu->size);
    xer_fprint(debug.log, &asn_DEF_ULP_PDU, pdu->pdu);
  }
#endif

  err = SSL_write(ctx->ssl, pdu->buffer, pdu->size);
  if (err <= 0) {
#if SUPL_DEBUG
    if (debug.debug) fprintf(debug.log, "Error: SSL_write error: %s\n", strerror(errno));
#endif
    return E_SUPL_WRITE;
  }

#ifdef SUPL_DEBUG
  debug.sent += pdu->size;
  debug.out_msg++;
#endif

  return 0;
}

int EXPORT supl_ulp_recv(supl_ctx_t *ctx, supl_ulp_t *pdu) {
  int err;
  int n;
  asn_dec_rval_t rval;
  ULP_PDU_t *length;

  err = SSL_read(ctx->ssl, pdu->buffer, sizeof(pdu->buffer));
  if (err <= 0) {
#ifdef SUPL_DEBUG
    if (debug.debug) fprintf(debug.log, "Error: SSL_read error: %s\n", strerror(errno));
#endif
    return E_SUPL_READ;
  }
  n = err;

  length = calloc(1, sizeof(ULP_PDU_t));
  // decode the very first bytes of the ULP_PDU message, just enough to the get message length
  rval = uper_decode_complete(0, &asn_DEF_ULP_PDU, (void **)&length, pdu->buffer, n < 6 ? n : 6);
  if (rval.code == RC_WMORE) {
    // read the missing data
    for (n = err; n < length->length; n += err) {
#ifdef SUPL_DEBUG
      if (debug.debug) fprintf(debug.log, "SSL_read got %u bytes (total %lu)\n", n, length->length);
#endif
      err = SSL_read(ctx->ssl, &pdu->buffer[n], sizeof(pdu->buffer)-n);
      if (err <= 0) {
#ifdef SUPL_DEBUG
	if (debug.debug) fprintf(debug.log, "Error: SSL_read (again) error: %s\n", strerror(errno));
#endif
	return E_SUPL_READ;
      }
    }
  }

  asn_DEF_ULP_PDU.free_struct(&asn_DEF_ULP_PDU, length, 0);

  pdu->size = n;

  if (supl_ulp_decode(pdu)) {
    return E_SUPL_DECODE;
  }

#ifdef SUPL_DEBUG
  if (debug.verbose_supl) {
    fprintf(debug.log, "Recv %lu bytes\n", pdu->size);
    xer_fprint(debug.log, &asn_DEF_ULP_PDU, pdu->pdu);
  }
#endif

#ifdef SUPL_DEBUG
  debug.recv += err;
  debug.in_msg++;
#endif

  return 0;
}

int EXPORT supl_decode_rrlp(supl_ulp_t *ulp_pdu, PDU_t **ret_rrlp) {
  asn_dec_rval_t rval;
  OCTET_STRING_t *rrlp_pdu;
  PDU_t *rrlp;
  ULP_PDU_t *ulp;

  ulp = ulp_pdu->pdu;

  if (!(ulp->message.present == UlpMessage_PR_msSUPLPOS &&
	ulp->message.choice.msSUPLPOS.posPayLoad.present == PosPayLoad_PR_rrlpPayload)) {
    return 0;
  }
  rrlp_pdu = &ulp->message.choice.msSUPLPOS.posPayLoad.choice.rrlpPayload;

  rrlp = calloc(1, sizeof(PDU_t));
  rval = uper_decode_complete(0, &asn_DEF_PDU, (void **)&rrlp, rrlp_pdu->buf, rrlp_pdu->size);
  switch (rval.code) {
  case RC_OK:
#ifdef SUPL_DEBUG
    if (rval.consumed != rrlp_pdu->size) {
      if (debug.debug) fprintf(debug.log, "Warning: %lu bytes left over in RRLP decoding\n", rval.consumed);
    }
#endif

    *ret_rrlp = rrlp;
    return 0;

  case RC_WMORE:
    asn_DEF_PDU.free_struct(&asn_DEF_PDU, rrlp, 0);
    ret_rrlp = 0;
    return E_SUPL_DECODE_RRLP;

  default:
    asn_DEF_PDU.free_struct(&asn_DEF_PDU, rrlp, 0);
    ret_rrlp = 0;
    return E_SUPL_DECODE_RRLP;
  }
  
  return E_SUPL_INTERNAL;
}
  
int EXPORT supl_server_connect(supl_ctx_t *ctx, char *server) {
  int err;
  const SSL_METHOD *meth;

  SSLeay_add_ssl_algorithms();
  // meth = TLSv1_client_method();
  meth = SSLv23_client_method();
  SSL_load_error_strings();
  ctx->ssl_ctx = SSL_CTX_new(meth);
  if (!ctx->ssl_ctx) return E_SUPL_CONNECT;
  
  ctx->ssl = SSL_new(ctx->ssl_ctx);
  if (!ctx->ssl) return E_SUPL_CONNECT;

  if (server) {
    ctx->fd = server_connect(server);
    if (ctx->fd == -1) return E_SUPL_CONNECT;
  }

  SSL_set_fd(ctx->ssl, ctx->fd);
  err = SSL_connect(ctx->ssl);
  if (err == -1) return E_SUPL_CONNECT;

#if 0
  {
    X509 *s_cert = SSL_get_peer_certificate(ctx->ssl);
    FILE *fp = fopen("/tmp/s_cert.pem", "w");
    if (fp) 
      PEM_write_X509(fp, s_cert);
    fclose(fp);
    X509_free(s_cert);
  }
#endif
	   
  return 0;
}

void EXPORT supl_close(supl_ctx_t *ctx) {
  SSL_shutdown(ctx->ssl);
  SSL_free(ctx->ssl);
  SSL_CTX_free(ctx->ssl_ctx);
  close(ctx->fd);
}


static int server_connect(char *server) {
  int fd = -1;
  struct addrinfo *ailist, *aip;
  struct addrinfo hint;
  int err;

  memset(&hint, 0, sizeof(struct addrinfo));
  hint.ai_socktype = SOCK_STREAM;
  err = getaddrinfo(server, SUPL_PORT, &hint, &ailist);
  if (err != 0) {
    return -1;
  }

  for (aip = ailist; aip; aip = aip->ai_next) {
    if ((fd = socket(aip->ai_family, SOCK_STREAM, 0)) < 0) {
      err = errno;
    }
    if (connect(fd, aip->ai_addr, aip->ai_addrlen) != 0) {
      return -1;
    }
    break;
  }

  return fd;
}

static int pdu_make_ulp_start(supl_ctx_t *ctx, supl_ulp_t *pdu) {
  ULP_PDU_t *ulp;
  SetSessionID_t *session_id;
  int err;

  ulp = calloc(1, sizeof(ULP_PDU_t));
  session_id = calloc(1, sizeof(SetSessionID_t));

  ulp->length = 0;
  ulp->version.maj = 1;
  ulp->version.min = 0;
  ulp->version.servind = 0;

  session_id->sessionId = 1;
  // session_id->setId.present = SETId_PR_msisdn;
  // (void)OCTET_STRING_fromBuf(&session_id->setId.choice.msisdn, ctx->p.msisdn, 8);
  session_id->setId.present = SETId_PR_imsi;
  (void)OCTET_STRING_fromBuf(&session_id->setId.choice.imsi, ctx->p.msisdn, 8);

  ulp->sessionID.setSessionID = session_id;
  ulp->sessionID.slpSessionID = OPTIONAL_MISSING;

  ulp->message.present = UlpMessage_PR_msSUPLSTART;
  ulp->message.choice.msSUPLSTART.sETCapabilities.posTechnology.agpsSETBased = 1;
  // (void)asn_long2INTEGER(&ulp->message.choice.msSUPLSTART.sETCapabilities.prefMethod, PrefMethod_noPreference);
  (void)asn_long2INTEGER(&ulp->message.choice.msSUPLSTART.sETCapabilities.prefMethod, PrefMethod_agpsSETBasedPreferred);
  ulp->message.choice.msSUPLSTART.sETCapabilities.posProtocol.rrlp = 1;

  if (ctx->p.set & PARAM_GSM_CELL_CURRENT) {
  ulp->message.choice.msSUPLSTART.locationId.cellInfo.present = CellInfo_PR_gsmCell; 
  ulp->message.choice.msSUPLSTART.locationId.cellInfo.choice.gsmCell.refMCC = ctx->p.gsm.mcc;
  ulp->message.choice.msSUPLSTART.locationId.cellInfo.choice.gsmCell.refMNC = ctx->p.gsm.mnc;
  ulp->message.choice.msSUPLSTART.locationId.cellInfo.choice.gsmCell.refLAC = ctx->p.gsm.lac;
  ulp->message.choice.msSUPLSTART.locationId.cellInfo.choice.gsmCell.refCI = ctx->p.gsm.ci;
  ulp->message.choice.msSUPLSTART.locationId.cellInfo.choice.gsmCell.nMR = OPTIONAL_MISSING; 
  ulp->message.choice.msSUPLSTART.locationId.cellInfo.choice.gsmCell.tA = OPTIONAL_MISSING; 
  } else if (ctx->p.set & PARAM_WCDMA_CELL_CURRENT) {
    ulp->message.choice.msSUPLSTART.locationId.cellInfo.present = CellInfo_PR_wcdmaCell; 
    ulp->message.choice.msSUPLSTART.locationId.cellInfo.choice.wcdmaCell.refMCC = ctx->p.wcdma.mcc;
    ulp->message.choice.msSUPLSTART.locationId.cellInfo.choice.wcdmaCell.refMNC = ctx->p.wcdma.mnc;
    ulp->message.choice.msSUPLSTART.locationId.cellInfo.choice.wcdmaCell.refUC = ctx->p.wcdma.uc;
  }

  (void)asn_long2INTEGER(&ulp->message.choice.msSUPLSTART.locationId.status, Status_current);

  ulp->message.choice.msSUPLSTART.qoP = OPTIONAL_MISSING;

  pdu->pdu = ulp;

  err = supl_ulp_encode(pdu);
  if (err < 0) {
    asn_DEF_ULP_PDU.free_struct(&asn_DEF_ULP_PDU, ulp, 0);
    return err;
  }

  return 0;
}

// get slpSessionID from SUPLRESPONSE pdu if preset
static int supl_response_harvest(supl_ctx_t *ctx, supl_ulp_t *pdu) {
  int ret;
  ULP_PDU_t *ulp = pdu->pdu;
  void *buf;

  ctx->slp_session_id.buf = 0;

  ret = uper_encode_to_new_buffer(&asn_DEF_SlpSessionID, 0, (void *)ulp->sessionID.slpSessionID, &buf);
  if (ret == -1) return -1;

  ctx->slp_session_id.buf = buf;
  ctx->slp_session_id.size = ret;

  return 0;
}

static int pdu_make_ulp_pos_init(supl_ctx_t *ctx, supl_ulp_t *pdu) {
  int err;
  ULP_PDU_t *ulp;
  SetSessionID_t *session_id;
  RequestedAssistData_t *req_adata;

  ulp = calloc(1, sizeof(ULP_PDU_t));
  session_id = calloc(1, sizeof(SetSessionID_t));
  req_adata = calloc(1, sizeof(RequestedAssistData_t));

  ulp->length = 0;
  ulp->version.maj = 1;
  ulp->version.min = 0;
  ulp->version.servind = 0;

  session_id->sessionId = 1;
  // session_id->setId.present = SETId_PR_msisdn;
  // (void)OCTET_STRING_fromBuf(&session_id->setId.choice.msisdn, ctx->p.msisdn, 8);
  session_id->setId.present = SETId_PR_imsi;
  (void)OCTET_STRING_fromBuf(&session_id->setId.choice.imsi, ctx->p.msisdn, 8);

  ulp->sessionID.setSessionID = session_id;
  // ulp->sessionID.slpSessionID = OPTIONAL_MISSING;
  if (ctx->slp_session_id.buf) {
    (void)uper_decode_complete(0, &asn_DEF_SlpSessionID, (void **)&ulp->sessionID.slpSessionID, ctx->slp_session_id.buf, ctx->slp_session_id.size);
  } else {
  ulp->sessionID.slpSessionID = OPTIONAL_MISSING;
  }

  ulp->message.present = UlpMessage_PR_msSUPLPOSINIT;
  ulp->message.choice.msSUPLPOSINIT.sETCapabilities.posTechnology.agpsSETBased = 1;
  // (void)asn_long2INTEGER(&ulp->message.choice.msSUPLPOSINIT.sETCapabilities.prefMethod, PrefMethod_noPreference);
  (void)asn_long2INTEGER(&ulp->message.choice.msSUPLPOSINIT.sETCapabilities.prefMethod, PrefMethod_agpsSETBasedPreferred);
  ulp->message.choice.msSUPLPOSINIT.sETCapabilities.posProtocol.rrlp = 1;

  //GNSS-SDR mod
  // Use ctx->p.request to swith between a pre-defined set of assistence data request
  // reason: Some SUPL servers do not respond to Acquisition assistance depending on the status of other assistance flags

  switch (ctx->p.request)
  {
  case 0: //request almanac, time, and cell positions
	  req_adata->acquisitionAssistanceRequested = 0; // 1
	  req_adata->navigationModelRequested = 0; // 1
	  req_adata->referenceTimeRequested = 1;
	  req_adata->utcModelRequested = 1; //1
	  req_adata->ionosphericModelRequested = 1; // 1
	  req_adata->referenceLocationRequested = 1;
	  req_adata->almanacRequested = 1;
	  req_adata->realTimeIntegrityRequested = 1; // 1
	  break;
  case 1: // request Navigation Model (Ephemeris)
	  req_adata->acquisitionAssistanceRequested = 0; // 1
	  req_adata->navigationModelRequested = 1; // 1
	  req_adata->referenceTimeRequested = 0;
	  req_adata->utcModelRequested = 0; //1
	  req_adata->ionosphericModelRequested = 0; // 1
	  req_adata->referenceLocationRequested = 0;
	  req_adata->almanacRequested = 0;
	  req_adata->realTimeIntegrityRequested = 0; // 1
	  break;
  case 2: //request Acquisition assistance (Doppler assistance)
	  req_adata->acquisitionAssistanceRequested = 1; // 1
	  req_adata->navigationModelRequested = 0; // 1
	  req_adata->referenceTimeRequested = 1;
	  req_adata->utcModelRequested = 1; //1
	  req_adata->ionosphericModelRequested = 1; // 1
	  req_adata->referenceLocationRequested = 1;
	  req_adata->almanacRequested = 1;
	  req_adata->realTimeIntegrityRequested = 1; // 1
	  break;
  default:
	  req_adata->acquisitionAssistanceRequested = 0; // 1
	  req_adata->navigationModelRequested = 0; // 1
	  req_adata->referenceTimeRequested = 1;
	  req_adata->utcModelRequested = 1; //1
	  req_adata->ionosphericModelRequested = 1; // 1
	  req_adata->referenceLocationRequested = 1;
	  req_adata->almanacRequested = 1;
	  req_adata->realTimeIntegrityRequested = 1; // 1
  break;
  }

  ulp->message.choice.msSUPLPOSINIT.requestedAssistData = req_adata;

  if (ctx->p.set & PARAM_GSM_CELL_CURRENT) {
  ulp->message.choice.msSUPLPOSINIT.locationId.cellInfo.present = CellInfo_PR_gsmCell; 
  ulp->message.choice.msSUPLPOSINIT.locationId.cellInfo.choice.gsmCell.refMCC = ctx->p.gsm.mcc;
  ulp->message.choice.msSUPLPOSINIT.locationId.cellInfo.choice.gsmCell.refMNC = ctx->p.gsm.mnc;
  ulp->message.choice.msSUPLPOSINIT.locationId.cellInfo.choice.gsmCell.refLAC = ctx->p.gsm.lac; 
  ulp->message.choice.msSUPLPOSINIT.locationId.cellInfo.choice.gsmCell.refCI = ctx->p.gsm.ci; 
  ulp->message.choice.msSUPLPOSINIT.locationId.cellInfo.choice.gsmCell.nMR = OPTIONAL_MISSING; 
  ulp->message.choice.msSUPLPOSINIT.locationId.cellInfo.choice.gsmCell.tA = OPTIONAL_MISSING; 
  } else if (ctx->p.set & PARAM_WCDMA_CELL_CURRENT) {
    ulp->message.choice.msSUPLPOSINIT.locationId.cellInfo.present = CellInfo_PR_wcdmaCell; 
    ulp->message.choice.msSUPLPOSINIT.locationId.cellInfo.choice.wcdmaCell.refMCC = ctx->p.wcdma.mcc;
    ulp->message.choice.msSUPLPOSINIT.locationId.cellInfo.choice.wcdmaCell.refMNC = ctx->p.wcdma.mnc;
    ulp->message.choice.msSUPLPOSINIT.locationId.cellInfo.choice.wcdmaCell.refUC = ctx->p.wcdma.uc;
  }

  if (ctx->p.set & PARAM_GSM_CELL_KNOWN) {
    Position_t *pos = calloc(1, sizeof(Position_t));
    struct tm *tm;
    time_t t;

    (void)asn_long2INTEGER(&ulp->message.choice.msSUPLPOSINIT.locationId.status, Status_stale);

    t = time(0);
    tm = gmtime(&t);
    asn_UT2time(&pos->timestamp, tm ,1);
    (void)asn_long2INTEGER(&pos->positionEstimate.latitudeSign, latitudeSign_north);
    pos->positionEstimate.latitude = (1 << 23) / 90.0 * ctx->p.known.lat;
    pos->positionEstimate.longitude = (1 << 24) / 360.0 * ctx->p.known.lon;
    // TODO: set position estimate

    ulp->message.choice.msSUPLPOSINIT.position = pos;
  } else {
    (void)asn_long2INTEGER(&ulp->message.choice.msSUPLPOSINIT.locationId.status, Status_current);
    ulp->message.choice.msSUPLPOSINIT.position = OPTIONAL_MISSING;
  }

  ulp->message.choice.msSUPLPOSINIT.sUPLPOS = OPTIONAL_MISSING;

  ulp->message.choice.msSUPLPOSINIT.ver = OPTIONAL_MISSING;

  pdu->pdu = ulp;

  err = supl_ulp_encode(pdu);
  if (err < 0) {
    asn_DEF_ULP_PDU.free_struct(&asn_DEF_ULP_PDU, ulp, 0);
    return err;
  }

  return 0;
}

static int pdu_make_ulp_rrlp_ack(supl_ctx_t *ctx, supl_ulp_t *pdu, PDU_t *rrlp) {
  int err;
  PDU_t *rrlp_ack;
  ULP_PDU_t *ulp;
  SetSessionID_t *session_id;
  asn_enc_rval_t ret;
  int pdu_len;
  char buffer[1024];

  rrlp_ack = calloc(1, sizeof(PDU_t));

  /* create RRLP assistanceDataAck */

  rrlp_ack->referenceNumber = rrlp->referenceNumber;
  rrlp_ack->component.present = RRLP_Component_PR_assistanceDataAck;
    
  ret = uper_encode_to_buffer(&asn_DEF_PDU, rrlp_ack, buffer, sizeof(buffer));
  asn_DEF_ULP_PDU.free_struct(&asn_DEF_PDU, rrlp_ack, 0);
  if (ret.encoded == -1) {
    return E_SUPL_ENCODE_RRLP;
  }
  pdu_len = (ret.encoded + 7) >> 3;

  /* embedded it in SUPLPOS */

  ulp = calloc(1, sizeof(ULP_PDU_t));
  session_id = calloc(1, sizeof(SetSessionID_t));
  
  ulp->length = 0;
  ulp->version.maj = 1;
  ulp->version.min = 0;
  ulp->version.servind = 0;
  
  session_id->sessionId = 1;
  //  session_id->setId.present = SETId_PR_msisdn;
  // (void)OCTET_STRING_fromBuf(&session_id->setId.choice.msisdn, ctx->p.msisdn, 8);
  session_id->setId.present = SETId_PR_imsi;
  (void)OCTET_STRING_fromBuf(&session_id->setId.choice.imsi, ctx->p.msisdn, 8);

  ulp->sessionID.setSessionID = session_id;
  // ulp->sessionID.slpSessionID = OPTIONAL_MISSING;
  if (ctx->slp_session_id.buf) {
    (void)uper_decode_complete(0, &asn_DEF_SlpSessionID, (void **)&ulp->sessionID.slpSessionID, ctx->slp_session_id.buf, ctx->slp_session_id.size);
  } else {
  ulp->sessionID.slpSessionID = OPTIONAL_MISSING;
  }

  ulp->message.present = UlpMessage_PR_msSUPLPOS;
  ulp->message.choice.msSUPLPOS.posPayLoad.present = PosPayLoad_PR_rrlpPayload;
  (void)OCTET_STRING_fromBuf(&ulp->message.choice.msSUPLPOS.posPayLoad.choice.rrlpPayload, buffer, pdu_len);

  pdu->pdu = ulp;

  err = supl_ulp_encode(pdu);
  if (err < 0) {
    supl_ulp_free(pdu);
    return err;
  }

  return 0;
}

/*
**
**
*/

int EXPORT supl_collect_rrlp(supl_assist_t *assist, PDU_t *rrlp, struct timeval *t) {
  ControlHeader_t *hdr;

  if (rrlp->component.present != RRLP_Component_PR_assistanceData) return 0;
  if (!rrlp->component.choice.assistanceData.gps_AssistData) return 0;

  hdr = &rrlp->component.choice.assistanceData.gps_AssistData->controlHeader;

  if (hdr->referenceTime) {
    assist->set |= SUPL_RRLP_ASSIST_REFTIME;
    assist->time.gps_tow = hdr->referenceTime->gpsTime.gpsTOW23b;
    assist->time.gps_week = hdr->referenceTime->gpsTime.gpsWeek;
    memcpy(&assist->time.stamp, t, sizeof(struct timeval));
  }

  if (hdr->refLocation) {
    OCTET_STRING_t *loc;

    loc = &hdr->refLocation->threeDLocation;
    if (loc->size == 14 && loc->buf[0] == 0x90) {
      double lat, lon;
      long l;

      /* from 3GPP TS 23.032 V4.0.0 (2001-04) */

      l = (loc->buf[1] & 0x7f) << 16 |
	  (loc->buf[2] << 8) |
	  loc->buf[3];
      if (loc->buf[1] & 0x80) l *= -1;
      lat = 90.0 / (1 << 23) * l;
      
      l = (loc->buf[4] << 16) |
	  (loc->buf[5] << 8) |
	  loc->buf[6];
      lon = 360.0 / (1 << 24) * l;

      /* max of uncertainty ellipsoid axis */
      /* uncert in meters = 10 * (1.1 ^ l - 1) */
      /* l == 96 => 100 km uncertainty => not usable */
      l = loc->buf[9];
      if (loc->buf[10] > l) l = loc->buf[10];

      assist->set |= SUPL_RRLP_ASSIST_REFLOC;
      assist->pos.lat = lat;
      assist->pos.lon = lon;
      assist->pos.uncertainty = l;
    }
  }
    
  if (hdr->acquisAssist) {
    int n;

    assist->acq_time = hdr->acquisAssist->timeRelation.gpsTOW;

    for (n = 0; n < hdr->acquisAssist->acquisList.list.count; n++) {
      struct AcquisElement *e = hdr->acquisAssist->acquisList.list.array[n];
      int i = assist->cnt_acq++;

      assist->acq[i].prn = e->svid + 1;
      assist->acq[i].parts = 0;
      assist->acq[i].doppler0 = e->doppler0;

      if (e->addionalDoppler) {
	assist->acq[i].parts |= SUPL_ACQUIS_DOPPLER;
	assist->acq[i].doppler1 = e->addionalDoppler->doppler1;
	assist->acq[i].d_win = e->addionalDoppler->dopplerUncertainty;
      }

      assist->acq[i].code_ph = e->codePhase;
      assist->acq[i].code_ph_int = e->intCodePhase;
      assist->acq[i].bit_num = e->gpsBitNumber;
      assist->acq[i].code_ph_win = e->codePhaseSearchWindow;

      if (e->addionalAngle) {
	assist->acq[i].parts |= SUPL_ACQUIS_ANGLE;
	assist->acq[i].az = e->addionalAngle->azimuth;
	assist->acq[i].el = e->addionalAngle->elevation;
      }
    }
  }

  if (hdr->almanac) {
    int n;

    for (n = 0; n < hdr->almanac->almanacList.list.count; n++) {
      struct AlmanacElement *e = hdr->almanac->almanacList.list.array[n];
      int i = assist->cnt_alm++;

      assist->alm[i].prn = e->satelliteID + 1;
      assist->alm[i].e = e->almanacE;
      assist->alm[i].toa = e->alamanacToa; // nice touch 3gpp
      assist->alm[i].Ksii = e->almanacKsii;
      assist->alm[i].OMEGA_dot = e->almanacOmegaDot;
      assist->alm[i].A_sqrt = e->almanacAPowerHalf;
      assist->alm[i].OMEGA_0 = e->almanacOmega0;
      assist->alm[i].w = e->almanacW;
      assist->alm[i].M0 = e->almanacM0;
      assist->alm[i].AF0 = e->almanacAF0;
      assist->alm[i].AF1 = e->almanacAF1;
    }
  }

  if (hdr->navigationModel) {
    UncompressedEphemeris_t *ue;
    int n;

    for (n = 0; n < hdr->navigationModel->navModelList.list.count; n++) {
      struct NavModelElement *e = hdr->navigationModel->navModelList.list.array[n];
      int i = assist->cnt_eph++;

      assist->eph[i].prn = e->satelliteID + 1;

      /* what is the difference between these two */
      ue = 0;
      if (e->satStatus.present == SatStatus_PR_newNaviModelUC)
	ue = &e->satStatus.choice.newNaviModelUC;
      if (e->satStatus.present == SatStatus_PR_newSatelliteAndModelUC)
	ue = &e->satStatus.choice.newSatelliteAndModelUC;

      if (ue) {
#if 0
	assist->eph_x[i].L2P = ue->ephemL2Pflag;
	assist->eph_x[i].fit = ue->ephemFitFlag;
#endif
	assist->eph[i].delta_n = ue->ephemDeltaN;
	assist->eph[i].M0 = ue->ephemM0;
#if 0
	// this is needed for asn1c version 0.9.22
	{
	  long v;
	  asn_INTEGER2long((INTEGER_t *)&ue->ephemE, &v);
	  assist->eph[i].e = v;
	  asn_INTEGER2long((INTEGER_t *)&ue->ephemAPowerHalf, &v);
	  assist->eph[i].e = v;
	}
#else
	assist->eph[i].e = ue->ephemE;
	assist->eph[i].A_sqrt = ue->ephemAPowerHalf;
#endif
	assist->eph[i].OMEGA_0 = ue->ephemOmegaA0;
	assist->eph[i].i0 = ue->ephemI0;
	assist->eph[i].w = ue->ephemW;
	assist->eph[i].OMEGA_dot = ue->ephemOmegaADot;
	assist->eph[i].i_dot = ue->ephemIDot;
	assist->eph[i].Cuc = ue->ephemCuc;
	assist->eph[i].Cus = ue->ephemCus;
	assist->eph[i].Crc = ue->ephemCrc;
	assist->eph[i].Crs = ue->ephemCrs;
	assist->eph[i].Cic = ue->ephemCic;
	assist->eph[i].Cis = ue->ephemCis;
	assist->eph[i].toe = ue->ephemToe;
	assist->eph[i].IODC = ue->ephemIODC;
	assist->eph[i].toc = ue->ephemToc;
	assist->eph[i].AF0 = ue->ephemAF0;
	assist->eph[i].AF1 = ue->ephemAF1;
	assist->eph[i].AF2 = ue->ephemAF2;

	assist->eph[i].nav_model = 1;
	assist->eph[i].bits = ue->ephemCodeOnL2;
	assist->eph[i].ura = ue->ephemURA;
	assist->eph[i].health = ue->ephemSVhealth;
	assist->eph[i].AODA = ue->ephemAODA;
	assist->eph[i].tgd = ue->ephemTgd;
      }
    }
  }

  if (hdr->ionosphericModel) {
    assist->set |= SUPL_RRLP_ASSIST_IONO;
    assist->iono.a0 = hdr->ionosphericModel->alfa0;
    assist->iono.a1 = hdr->ionosphericModel->alfa1;
    assist->iono.a2 = hdr->ionosphericModel->alfa2;
    assist->iono.a3 = hdr->ionosphericModel->alfa3; //missed in original supl client
    assist->iono.b0 = hdr->ionosphericModel->beta0;
    assist->iono.b1 = hdr->ionosphericModel->beta1;
    assist->iono.b2 = hdr->ionosphericModel->beta2;
    assist->iono.b3 = hdr->ionosphericModel->beta3;
  }

  if (hdr->utcModel) {
    assist->set |= SUPL_RRLP_ASSIST_UTC;
    assist->utc.a0 = hdr->utcModel->utcA0;
    assist->utc.a1 = hdr->utcModel->utcA1;
    assist->utc.tot = hdr->utcModel->utcTot;
    assist->utc.wnt = hdr->utcModel->utcWNt;
    assist->utc.delta_tls = hdr->utcModel->utcDeltaTls;
    assist->utc.wnlsf = hdr->utcModel->utcWNlsf;
    assist->utc.dn = hdr->utcModel->utcDN;
    assist->utc.delta_tlsf = hdr->utcModel->utcDeltaTlsf;
  }

  return 1;
}

int EXPORT supl_ctx_new(supl_ctx_t *ctx) {
  memset(ctx, 0, sizeof(supl_ctx_t));
#ifdef SUPL_DEBUG
  memset(&debug, 0, sizeof(struct supl_debug_s));
#endif

  return 0;
}

int EXPORT supl_ctx_free(supl_ctx_t *ctx) {
  if (ctx->slp_session_id.buf) {
    free(ctx->slp_session_id.buf);
    ctx->slp_session_id.buf = 0;
  }

  return 0;
}

static int supl_more_rrlp(PDU_t *rrlp) {
  long value;

  return (rrlp->component.present == RRLP_Component_PR_assistanceData &&
	  rrlp->component.choice.assistanceData.moreAssDataToBeSent &&
	  asn_INTEGER2long((INTEGER_t *)rrlp->component.choice.assistanceData.moreAssDataToBeSent, &value) == 0 &&
	  value == MoreAssDataToBeSent_moreMessagesOnTheWay);
}

int EXPORT supl_get_assist(supl_ctx_t *ctx, char *server, supl_assist_t *assist) {
  supl_ulp_t ulp;

  //  memcpy(ctx->p.msisdn, "\xde\xad\xbe\xef\xf0\x0b\xaa\x42", 8);
  memcpy(ctx->p.msisdn, "\xFF\xFF\x91\x94\x48\x45\x83\x98", 8);

  /*
  ** connect to server
  */

  if (supl_server_connect(ctx, server) < 0) return E_SUPL_CONNECT;

  /*
  ** send SUPL_START
  */

  if (pdu_make_ulp_start(ctx, &ulp) < 0) {
    return E_SUPL_ENCODE_START;
  }

  (void)supl_ulp_send(ctx, &ulp);
  supl_ulp_free(&ulp);

  /*
  ** should receive SUPL_RESPONSE back
  */

  if (supl_ulp_recv(ctx, &ulp) < 0) {
    return E_SUPL_RECV_RESPONSE;
  }

  if (ulp.pdu->message.present != UlpMessage_PR_msSUPLRESPONSE) {
    supl_ulp_free(&ulp);
    return E_SUPL_SUPLRESPONSE;
  }

  // get and copy slpSessionID if present
  supl_response_harvest(ctx, &ulp);

  supl_ulp_free(&ulp);
  
  /*
  ** send SUPL_POS_INIT
  */

  if (pdu_make_ulp_pos_init(ctx, &ulp) < 0) {
    return E_SUPL_ENCODE_POSINIT;
  }

  (void)supl_ulp_send(ctx, &ulp);

  /*
  ** should get SUPLPOS back - bounce back and forth until all messages have arrived
  */

  memset(assist, 0, sizeof(supl_assist_t));

  while (1) {
    struct timeval t;
    PDU_t *rrlp;

    supl_ulp_free(&ulp);

    /* record packet recv time */
    gettimeofday(&t, 0);

    if (supl_ulp_recv(ctx, &ulp) < 0) {
      return E_SUPL_RECV_SUPLPOS;
    }

    if (ulp.pdu->message.present == UlpMessage_PR_msSUPLEND) {
      break;
    }

    if (ulp.pdu->message.present != UlpMessage_PR_msSUPLPOS) {
      supl_ulp_free(&ulp);
      return E_SUPL_SUPLPOS;
    }

    /* get the beef, the RRLP payload */

    if (supl_decode_rrlp(&ulp, &rrlp) < 0) {
      supl_ulp_free(&ulp);
      return E_SUPL_DECODE_RRLP;
    }

#ifdef SUPL_DEBUG
    if (debug.verbose_rrlp) {
      fprintf(debug.log, "Embedded RRLP message\n");
      xer_fprint(debug.log, &asn_DEF_PDU, rrlp);
    }
#endif

    /* remember important stuff from it */

    supl_collect_rrlp(assist, rrlp, &t);

    if (!supl_more_rrlp(rrlp)) {
      asn_DEF_ULP_PDU.free_struct(&asn_DEF_PDU, rrlp, 0);
      break;
    }

    /* More data coming in, send SUPLPOS + RRLP ACK */

    if (pdu_make_ulp_rrlp_ack(ctx, &ulp, rrlp) < 0) {
      return E_SUPL_RRLP_ACK;
    }

    supl_ulp_send(ctx, &ulp);
    asn_DEF_ULP_PDU.free_struct(&asn_DEF_PDU, rrlp, 0);
  }

  supl_ulp_free(&ulp);

  /*
  ** send SUPL_END (but who really cares)
  */

  supl_close(ctx);

  return 0;
}

void EXPORT supl_set_gsm_cell(supl_ctx_t *ctx, int mcc, int mns, int lac, int ci) {
  ctx->p.set |= PARAM_GSM_CELL_CURRENT;

  ctx->p.gsm.mcc = mcc;
  ctx->p.gsm.mnc = mns;
  ctx->p.gsm.lac = lac;
  ctx->p.gsm.ci = ci;
}

void EXPORT supl_set_gsm_cell_known(supl_ctx_t *ctx, int mcc, int mns, int lac, int ci, double lat, double lon, int uncert) {
  ctx->p.set |= PARAM_GSM_CELL_KNOWN;

  ctx->p.known.mcc = mcc;
  ctx->p.known.mnc = mns;
  ctx->p.known.lac = lac;
  ctx->p.known.ci = ci;
  ctx->p.known.lat = lat;
  ctx->p.known.lon = lon;
  ctx->p.known.uncert = uncert;
}

void EXPORT supl_set_wcdma_cell(supl_ctx_t *ctx, int mcc, int mns, int uc) {
  ctx->p.set |= PARAM_WCDMA_CELL_CURRENT;

  ctx->p.wcdma.mcc = mcc;
  ctx->p.wcdma.mnc = mns;
  ctx->p.wcdma.uc = uc;
}

void EXPORT supl_request(supl_ctx_t *ctx, int request) {
  ctx->p.request = request;
}

void EXPORT supl_set_debug(FILE *log, int flags) {
#ifdef SUPL_DEBUG
  debug.log = log;
  if (flags & SUPL_DEBUG_RRLP) debug.verbose_rrlp = 1;
  if (flags & SUPL_DEBUG_SUPL) debug.verbose_supl = 1;
  if (flags & SUPL_DEBUG_DEBUG) debug.debug = 1;
#endif
}