scd/iso7816.c

   1 /* iso7816.c - ISO 7816 commands
   2  *      Copyright (C) 2003, 2004 Free Software Foundation, Inc.
   3  *
   4  * This file is part of GnuPG.
   5  *
   6  * GnuPG is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 3 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * GnuPG is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, see <http://www.gnu.org/licenses/>.
  18  *
  19  * $Id$
  20  */
  21
  22 #include <config.h>
  23 #include <errno.h>
  24 #include <stdio.h>
  25 #include <stdlib.h>
  26 #include <string.h>
  27
  28 #if defined(GNUPG_SCD_MAIN_HEADER)
  29 #include GNUPG_SCD_MAIN_HEADER
  30 #elif GNUPG_MAJOR_VERSION == 1
  31 /* This is used with GnuPG version < 1.9.  The code has been source
  32    copied from the current GnuPG >= 1.9  and is maintained over
  33    there. */
  34 #include "options.h"
  35 #include "errors.h"
  36 #include "memory.h"
  37 #include "util.h"
  38 #include "i18n.h"
  39 #else /* GNUPG_MAJOR_VERSION != 1 */
  40 #include "scdaemon.h"
  41 #endif /* GNUPG_MAJOR_VERSION != 1 */
  42
  43 #include "iso7816.h"
  44 #include "apdu.h"
  45
  46
  47 #define CMD_SELECT_FILE 0xA4
  48 #define CMD_VERIFY                ISO7816_VERIFY
  49 #define CMD_CHANGE_REFERENCE_DATA ISO7816_CHANGE_REFERENCE_DATA
  50 #define CMD_RESET_RETRY_COUNTER   ISO7816_RESET_RETRY_COUNTER
  51 #define CMD_GET_DATA    0xCA
  52 #define CMD_PUT_DATA    0xDA
  53 #define CMD_MSE         0x22
  54 #define CMD_PSO         0x2A
  55 #define CMD_INTERNAL_AUTHENTICATE 0x88
  56 #define CMD_GENERATE_KEYPAIR      0x47
  57 #define CMD_GET_CHALLENGE         0x84
  58 #define CMD_READ_BINARY 0xB0
  59 #define CMD_READ_RECORD 0xB2
  60
  61 static gpg_error_t
  62 map_sw (int sw)
  63 {
  64   gpg_err_code_t ec;
  65
  66   switch (sw)
  67     {
  68     case SW_EEPROM_FAILURE: ec = GPG_ERR_HARDWARE; break;
  69     case SW_WRONG_LENGTH:   ec = GPG_ERR_INV_VALUE; break;
  70     case SW_CHV_WRONG:      ec = GPG_ERR_BAD_PIN; break;
  71     case SW_CHV_BLOCKED:    ec = GPG_ERR_PIN_BLOCKED; break;
  72     case SW_USE_CONDITIONS: ec = GPG_ERR_USE_CONDITIONS; break;
  73     case SW_NOT_SUPPORTED:  ec = GPG_ERR_NOT_SUPPORTED; break;
  74     case SW_BAD_PARAMETER:  ec = GPG_ERR_INV_VALUE; break;
  75     case SW_FILE_NOT_FOUND: ec = GPG_ERR_ENOENT; break;
  76     case SW_RECORD_NOT_FOUND:ec= GPG_ERR_NOT_FOUND; break;
  77     case SW_REF_NOT_FOUND:  ec = GPG_ERR_NO_OBJ; break;
  78     case SW_BAD_P0_P1:      ec = GPG_ERR_INV_VALUE; break;
  79     case SW_EXACT_LENGTH:   ec = GPG_ERR_INV_VALUE; break;
  80     case SW_INS_NOT_SUP:    ec = GPG_ERR_CARD; break;
  81     case SW_CLA_NOT_SUP:    ec = GPG_ERR_CARD; break;
  82     case SW_SUCCESS:        ec = 0; break;
  83
  84     case SW_HOST_OUT_OF_CORE: ec = GPG_ERR_ENOMEM; break;
  85     case SW_HOST_INV_VALUE:   ec = GPG_ERR_INV_VALUE; break;
  86     case SW_HOST_INCOMPLETE_CARD_RESPONSE: ec = GPG_ERR_CARD; break;
  87     case SW_HOST_NOT_SUPPORTED: ec = GPG_ERR_NOT_SUPPORTED; break;
  88     case SW_HOST_LOCKING_FAILED: ec = GPG_ERR_BUG; break;
  89     case SW_HOST_BUSY:           ec = GPG_ERR_EBUSY; break;
  90     case SW_HOST_NO_CARD:        ec = GPG_ERR_CARD_NOT_PRESENT; break;
  91     case SW_HOST_CARD_INACTIVE:  ec = GPG_ERR_CARD_RESET; break;
  92     case SW_HOST_CARD_IO_ERROR:  ec = GPG_ERR_EIO; break;
  93     case SW_HOST_GENERAL_ERROR:  ec = GPG_ERR_GENERAL; break;
  94     case SW_HOST_NO_READER:      ec = GPG_ERR_ENODEV; break;
  95     case SW_HOST_ABORTED:        ec = GPG_ERR_CANCELED; break;
  96     case SW_HOST_NO_KEYPAD:      ec = GPG_ERR_NOT_SUPPORTED; break;
  97
  98     default:
  99       if ((sw & 0x010000))
 100         ec = GPG_ERR_GENERAL; /* Should not happen. */
 101       else if ((sw & 0xff00) == SW_MORE_DATA)
 102         ec = 0; /* This should actually never been seen here. */
 103       else
 104         ec = GPG_ERR_CARD;
 105     }
 106   return gpg_error (ec);
 107 }
 108
 109 /* Map a status word from the APDU layer to a gpg-error code.  */
 110 gpg_error_t
 111 iso7816_map_sw (int sw)
 112 {
 113   /* All APDU functions should return 0x9000 on success but for
 114      historical reasons of the implementation some return 0 to
 115      indicate success.  We allow for that here. */
 116   return sw? map_sw (sw) : 0;
 117 }
 118
 119
 120 /* This function is specialized version of the SELECT FILE command.
 121    SLOT is the card and reader as created for example by
 122    apdu_open_reader (), AID is a buffer of size AIDLEN holding the
 123    requested application ID.  The function can't be used to enumerate
 124    AIDs and won't return the AID on success.  The return value is 0
 125    for okay or a GPG error code.  Note that ISO error codes are
 126    internally mapped.  Bit 0 of FLAGS should be set if the card does
 127    not understand P2=0xC0. */
 128 gpg_error_t
 129 iso7816_select_application (int slot, const char *aid, size_t aidlen,
 130                             unsigned int flags)
 131 {
 132   int sw;
 133   sw = apdu_send_simple (slot, 0x00, CMD_SELECT_FILE, 4,
 134                          (flags&1)? 0 :0x0c, aidlen, aid);
 135   return map_sw (sw);
 136 }
 137
 138
 139 gpg_error_t
 140 iso7816_select_file (int slot, int tag, int is_dir,
 141                      unsigned char **result, size_t *resultlen)
 142 {
 143   int sw, p0, p1;
 144   unsigned char tagbuf[2];
 145
 146   tagbuf[0] = (tag >> 8) & 0xff;
 147   tagbuf[1] = tag & 0xff;
 148
 149   if (result || resultlen)
 150     {
 151       *result = NULL;
 152       *resultlen = 0;
 153       return gpg_error (GPG_ERR_NOT_IMPLEMENTED);
 154     }
 155   else
 156     {
 157       p0 = (tag == 0x3F00)? 0: is_dir? 1:2;
 158       p1 = 0x0c; /* No FC return. */
 159       sw = apdu_send_simple (slot, 0x00, CMD_SELECT_FILE,
 160                              p0, p1, 2, (char*)tagbuf );
 161       return map_sw (sw);
 162     }
 163
 164   return 0;
 165 }
 166
 167
 168 /* Do a select file command with a direct path. */
 169 gpg_error_t
 170 iso7816_select_path (int slot, const unsigned short *path, size_t pathlen,
 171                      unsigned char **result, size_t *resultlen)
 172 {
 173   int sw, p0, p1;
 174   unsigned char buffer[100];
 175   int buflen;
 176
 177   if (result || resultlen)
 178     {
 179       *result = NULL;
 180       *resultlen = 0;
 181       return gpg_error (GPG_ERR_NOT_IMPLEMENTED);
 182     }
 183
 184   if (pathlen/2 >= sizeof buffer)
 185     return gpg_error (GPG_ERR_TOO_LARGE);
 186
 187   for (buflen = 0; pathlen; pathlen--, path++)
 188     {
 189       buffer[buflen++] = (*path >> 8);
 190       buffer[buflen++] = *path;
 191     }
 192
 193   p0 = 0x08;
 194   p1 = 0x0c; /* No FC return. */
 195   sw = apdu_send_simple (slot, 0x00, CMD_SELECT_FILE,
 196                          p0, p1, buflen, (char*)buffer );
 197   return map_sw (sw);
 198 }
 199
 200
 201 /* This is a private command currently only working for TCOS cards. */
 202 gpg_error_t
 203 iso7816_list_directory (int slot, int list_dirs,
 204                         unsigned char **result, size_t *resultlen)
 205 {
 206   int sw;
 207
 208   if (!result || !resultlen)
 209     return gpg_error (GPG_ERR_INV_VALUE);
 210   *result = NULL;
 211   *resultlen = 0;
 212
 213   sw = apdu_send (slot, 0x80, 0xAA, list_dirs? 1:2, 0, -1, NULL,
 214                   result, resultlen);
 215   if (sw != SW_SUCCESS)
 216     {
 217       /* Make sure that pending buffers are released. */
 218       xfree (*result);
 219       *result = NULL;
 220       *resultlen = 0;
 221     }
 222   return map_sw (sw);
 223 }
 224
 225
 226 /* Check whether the reader supports the ISO command code COMMAND on
 227    the keypad.  Returns 0 on success.  */
 228 gpg_error_t
 229 iso7816_check_keypad (int slot, int command, iso7816_pininfo_t *pininfo)
 230 {
 231   int sw;
 232
 233   sw = apdu_check_keypad (slot, command,
 234                           pininfo->mode, pininfo->minlen, pininfo->maxlen,
 235                           pininfo->padlen);
 236   return iso7816_map_sw (sw);
 237 }
 238
 239
 240 /* Perform a VERIFY command on SLOT using the card holder verification
 241    vector CHVNO with a CHV of lenght CHVLEN.  With PININFO non-NULL
 242    the keypad of the reader will be used.  Returns 0 on success. */
 243 gpg_error_t
 244 iso7816_verify_kp (int slot, int chvno, const char *chv, size_t chvlen,
 245                    iso7816_pininfo_t *pininfo)
 246 {
 247   int sw;
 248
 249   if (pininfo && pininfo->mode)
 250     sw = apdu_send_simple_kp (slot, 0x00, CMD_VERIFY, 0, chvno, chvlen, chv,
 251                               pininfo->mode,
 252                               pininfo->minlen,
 253                               pininfo->maxlen,
 254                               pininfo->padlen);
 255   else
 256     sw = apdu_send_simple (slot, 0x00, CMD_VERIFY, 0, chvno, chvlen, chv);
 257   return map_sw (sw);
 258 }
 259
 260 /* Perform a VERIFY command on SLOT using the card holder verification
 261    vector CHVNO with a CHV of lenght CHVLEN.  Returns 0 on success. */
 262 gpg_error_t
 263 iso7816_verify (int slot, int chvno, const char *chv, size_t chvlen)
 264 {
 265   return iso7816_verify_kp (slot, chvno, chv, chvlen, NULL);
 266 }
 267
 268 /* Perform a CHANGE_REFERENCE_DATA command on SLOT for the card holder
 269    verification vector CHVNO.  If the OLDCHV is NULL (and OLDCHVLEN
 270    0), a "change reference data" is done, otherwise an "exchange
 271    reference data".  The new reference data is expected in NEWCHV of
 272    length NEWCHVLEN.  With PININFO non-NULL the keypad of the reader
 273    will be used.  */
 274 gpg_error_t
 275 iso7816_change_reference_data_kp (int slot, int chvno,
 276                                   const char *oldchv, size_t oldchvlen,
 277                                   const char *newchv, size_t newchvlen,
 278                                   iso7816_pininfo_t *pininfo)
 279 {
 280   int sw;
 281   char *buf;
 282
 283   if ((!oldchv && oldchvlen)
 284       || (oldchv && !oldchvlen)
 285       || !newchv || !newchvlen )
 286     return gpg_error (GPG_ERR_INV_VALUE);
 287
 288   buf = xtrymalloc (oldchvlen + newchvlen);
 289   if (!buf)
 290     return gpg_error (gpg_err_code_from_errno (errno));
 291   if (oldchvlen)
 292     memcpy (buf, oldchv, oldchvlen);
 293   memcpy (buf+oldchvlen, newchv, newchvlen);
 294
 295   if (pininfo && pininfo->mode)
 296     sw = apdu_send_simple_kp (slot, 0x00, CMD_CHANGE_REFERENCE_DATA,
 297                            oldchvlen? 0 : 1, chvno, oldchvlen+newchvlen, buf,
 298                            pininfo->mode,
 299                            pininfo->minlen,
 300                            pininfo->maxlen,
 301                            pininfo->padlen);
 302   else
 303     sw = apdu_send_simple (slot, 0x00, CMD_CHANGE_REFERENCE_DATA,
 304                            oldchvlen? 0 : 1, chvno, oldchvlen+newchvlen, buf);
 305   xfree (buf);
 306   return map_sw (sw);
 307
 308 }
 309
 310 /* Perform a CHANGE_REFERENCE_DATA command on SLOT for the card holder
 311    verification vector CHVNO.  If the OLDCHV is NULL (and OLDCHVLEN
 312    0), a "change reference data" is done, otherwise an "exchange
 313    reference data".  The new reference data is expected in NEWCHV of
 314    length NEWCHVLEN.  */
 315 gpg_error_t
 316 iso7816_change_reference_data (int slot, int chvno,
 317                                const char *oldchv, size_t oldchvlen,
 318                                const char *newchv, size_t newchvlen)
 319 {
 320   return iso7816_change_reference_data_kp (slot, chvno, oldchv, oldchvlen,
 321                                            newchv, newchvlen, NULL);
 322 }
 323
 324
 325 gpg_error_t
 326 iso7816_reset_retry_counter_kp (int slot, int chvno,
 327                                 const char *newchv, size_t newchvlen,
 328                                 iso7816_pininfo_t *pininfo)
 329 {
 330   int sw;
 331
 332   if (!newchv || !newchvlen )
 333     return gpg_error (GPG_ERR_INV_VALUE);
 334
 335   if (pininfo && pininfo->mode)
 336     sw = apdu_send_simple_kp (slot, 0x00, CMD_RESET_RETRY_COUNTER,
 337                            2, chvno, newchvlen, newchv,
 338                            pininfo->mode,
 339                            pininfo->minlen,
 340                            pininfo->maxlen,
 341                            pininfo->padlen);
 342   else
 343     sw = apdu_send_simple (slot, 0x00, CMD_RESET_RETRY_COUNTER,
 344                            2, chvno, newchvlen, newchv);
 345   return map_sw (sw);
 346 }
 347
 348
 349 gpg_error_t
 350 iso7816_reset_retry_counter (int slot, int chvno,
 351                              const char *newchv, size_t newchvlen)
 352 {
 353   return iso7816_reset_retry_counter_kp (slot, chvno, newchv, newchvlen, NULL);
 354 }
 355
 356
 357
 358 /* Perform a GET DATA command requesting TAG and storing the result in
 359    a newly allocated buffer at the address passed by RESULT.  Return
 360    the length of this data at the address of RESULTLEN. */
 361 gpg_error_t
 362 iso7816_get_data (int slot, int tag,
 363                   unsigned char **result, size_t *resultlen)
 364 {
 365   int sw;
 366
 367   if (!result || !resultlen)
 368     return gpg_error (GPG_ERR_INV_VALUE);
 369   *result = NULL;
 370   *resultlen = 0;
 371
 372   sw = apdu_send (slot, 0x00, CMD_GET_DATA,
 373                   ((tag >> 8) & 0xff), (tag & 0xff), -1, NULL,
 374                   result, resultlen);
 375   if (sw != SW_SUCCESS)
 376     {
 377       /* Make sure that pending buffers are released. */
 378       xfree (*result);
 379       *result = NULL;
 380       *resultlen = 0;
 381       return map_sw (sw);
 382     }
 383
 384   return 0;
 385 }
 386
 387
 388 /* Perform a PUT DATA command on card in SLOT.  Write DATA of length
 389    DATALEN to TAG. */
 390 gpg_error_t
 391 iso7816_put_data (int slot, int tag,
 392                   const unsigned char *data, size_t datalen)
 393 {
 394   int sw;
 395
 396   sw = apdu_send_simple (slot, 0x00, CMD_PUT_DATA,
 397                          ((tag >> 8) & 0xff), (tag & 0xff),
 398                          datalen, (const char*)data);
 399   return map_sw (sw);
 400 }
 401
 402 /* Manage Security Environment.  This is a weird operation and there
 403    is no easy abstraction for it.  Furthermore, some card seem to have
 404    a different interpreation of 7816-8 and thus we resort to let the
 405    caller decide what to do. */
 406 gpg_error_t
 407 iso7816_manage_security_env (int slot, int p1, int p2,
 408                              const unsigned char *data, size_t datalen)
 409 {
 410   int sw;
 411
 412   if (p1 < 0 || p1 > 255 || p2 < 0 || p2 > 255 )
 413     return gpg_error (GPG_ERR_INV_VALUE);
 414
 415   sw = apdu_send_simple (slot, 0x00, CMD_MSE, p1, p2,
 416                          data? datalen : -1, (const char*)data);
 417   return map_sw (sw);
 418 }
 419
 420
 421 /* Perform the security operation COMPUTE DIGITAL SIGANTURE.  On
 422    success 0 is returned and the data is availavle in a newly
 423    allocated buffer stored at RESULT with its length stored at
 424    RESULTLEN. */
 425 gpg_error_t
 426 iso7816_compute_ds (int slot, const unsigned char *data, size_t datalen,
 427                     unsigned char **result, size_t *resultlen)
 428 {
 429   int sw;
 430
 431   if (!data || !datalen || !result || !resultlen)
 432     return gpg_error (GPG_ERR_INV_VALUE);
 433   *result = NULL;
 434   *resultlen = 0;
 435
 436   sw = apdu_send (slot, 0x00, CMD_PSO, 0x9E, 0x9A, datalen, (const char*)data,
 437                   result, resultlen);
 438   if (sw != SW_SUCCESS)
 439     {
 440       /* Make sure that pending buffers are released. */
 441       xfree (*result);
 442       *result = NULL;
 443       *resultlen = 0;
 444       return map_sw (sw);
 445     }
 446
 447   return 0;
 448 }
 449
 450
 451 /* Perform the security operation DECIPHER.  PADIND is the padding
 452    indicator to be used.  It should be 0 if no padding is required, a
 453    value of -1 suppresses the padding byte.  On success 0 is returned
 454    and the plaintext is available in a newly allocated buffer stored
 455    at RESULT with its length stored at RESULTLEN. */
 456 gpg_error_t
 457 iso7816_decipher (int slot, const unsigned char *data, size_t datalen,
 458                   int padind, unsigned char **result, size_t *resultlen)
 459 {
 460   int sw;
 461   unsigned char *buf;
 462
 463   if (!data || !datalen || !result || !resultlen)
 464     return gpg_error (GPG_ERR_INV_VALUE);
 465   *result = NULL;
 466   *resultlen = 0;
 467
 468   if (padind >= 0)
 469     {
 470       /* We need to prepend the padding indicator. */
 471       buf = xtrymalloc (datalen + 1);
 472       if (!buf)
 473         return gpg_error (gpg_err_code_from_errno (errno));
 474
 475       *buf = padind; /* Padding indicator. */
 476       memcpy (buf+1, data, datalen);
 477       sw = apdu_send (slot, 0x00, CMD_PSO, 0x80, 0x86,
 478                       datalen+1, (char*)buf,
 479                       result, resultlen);
 480       xfree (buf);
 481     }
 482   else
 483     {
 484       sw = apdu_send (slot, 0x00, CMD_PSO, 0x80, 0x86,
 485                       datalen, (const char *)data,
 486                       result, resultlen);
 487     }
 488   if (sw != SW_SUCCESS)
 489     {
 490       /* Make sure that pending buffers are released. */
 491       xfree (*result);
 492       *result = NULL;
 493       *resultlen = 0;
 494       return map_sw (sw);
 495     }
 496
 497   return 0;
 498 }
 499
 500
 501 gpg_error_t
 502 iso7816_internal_authenticate (int slot,
 503                                const unsigned char *data, size_t datalen,
 504                                unsigned char **result, size_t *resultlen)
 505 {
 506   int sw;
 507
 508   if (!data || !datalen || !result || !resultlen)
 509     return gpg_error (GPG_ERR_INV_VALUE);
 510   *result = NULL;
 511   *resultlen = 0;
 512
 513   sw = apdu_send (slot, 0x00, CMD_INTERNAL_AUTHENTICATE, 0, 0,
 514                   datalen, (const char*)data,  result, resultlen);
 515   if (sw != SW_SUCCESS)
 516     {
 517       /* Make sure that pending buffers are released. */
 518       xfree (*result);
 519       *result = NULL;
 520       *resultlen = 0;
 521       return map_sw (sw);
 522     }
 523
 524   return 0;
 525 }
 526
 527
 528 static gpg_error_t
 529 do_generate_keypair (int slot, int readonly,
 530                   const unsigned char *data, size_t datalen,
 531                   unsigned char **result, size_t *resultlen)
 532 {
 533   int sw;
 534
 535   if (!data || !datalen || !result || !resultlen)
 536     return gpg_error (GPG_ERR_INV_VALUE);
 537   *result = NULL;
 538   *resultlen = 0;
 539
 540   sw = apdu_send (slot, 0x00, CMD_GENERATE_KEYPAIR, readonly? 0x81:0x80, 0,
 541                   datalen, (const char*)data,  result, resultlen);
 542   if (sw != SW_SUCCESS)
 543     {
 544       /* Make sure that pending buffers are released. */
 545       xfree (*result);
 546       *result = NULL;
 547       *resultlen = 0;
 548       return map_sw (sw);
 549     }
 550
 551   return 0;
 552 }
 553
 554
 555 gpg_error_t
 556 iso7816_generate_keypair (int slot,
 557                           const unsigned char *data, size_t datalen,
 558                           unsigned char **result, size_t *resultlen)
 559 {
 560   return do_generate_keypair (slot, 0, data, datalen, result, resultlen);
 561 }
 562
 563
 564 gpg_error_t
 565 iso7816_read_public_key (int slot,
 566                           const unsigned char *data, size_t datalen,
 567                           unsigned char **result, size_t *resultlen)
 568 {
 569   return do_generate_keypair (slot, 1, data, datalen, result, resultlen);
 570 }
 571
 572
 573
 574 gpg_error_t
 575 iso7816_get_challenge (int slot, int length, unsigned char *buffer)
 576 {
 577   int sw;
 578   unsigned char *result;
 579   size_t resultlen, n;
 580
 581   if (!buffer || length < 1)
 582     return gpg_error (GPG_ERR_INV_VALUE);
 583
 584   do
 585     {
 586       result = NULL;
 587       n = length > 254? 254 : length;
 588       sw = apdu_send_le (slot, 0x00, CMD_GET_CHALLENGE, 0, 0, -1, NULL,
 589                          n,
 590                          &result, &resultlen);
 591       if (sw != SW_SUCCESS)
 592         {
 593           /* Make sure that pending buffers are released. */
 594           xfree (result);
 595           return map_sw (sw);
 596         }
 597       if (resultlen > n)
 598         resultlen = n;
 599       memcpy (buffer, result, resultlen);
 600       buffer += resultlen;
 601       length -= resultlen;
 602       xfree (result);
 603     }
 604   while (length > 0);
 605
 606   return 0;
 607 }
 608
 609 /* Perform a READ BINARY command requesting a maximum of NMAX bytes
 610    from OFFSET.  With NMAX = 0 the entire file is read. The result is
 611    stored in a newly allocated buffer at the address passed by RESULT.
 612    Returns the length of this data at the address of RESULTLEN. */
 613 gpg_error_t
 614 iso7816_read_binary (int slot, size_t offset, size_t nmax,
 615                      unsigned char **result, size_t *resultlen)
 616 {
 617   int sw;
 618   unsigned char *buffer;
 619   size_t bufferlen;
 620   int read_all = !nmax;
 621   size_t n;
 622
 623   if (!result || !resultlen)
 624     return gpg_error (GPG_ERR_INV_VALUE);
 625   *result = NULL;
 626   *resultlen = 0;
 627
 628   /* We can only encode 15 bits in p0,p1 to indicate an offset. Thus
 629      we check for this limit. */
 630   if (offset > 32767)
 631     return gpg_error (GPG_ERR_INV_VALUE);
 632
 633   do
 634     {
 635       buffer = NULL;
 636       bufferlen = 0;
 637       /* Note, that we to set N to 254 due to problems either with the
 638          ccid driver or some TCOS cards.  It actually should be 0
 639          which is the official ISO value to read a variable length
 640          object. */
 641       if (read_all || nmax > 254)
 642         n = 254;
 643       else
 644         n = nmax;
 645       sw = apdu_send_le (slot, 0x00, CMD_READ_BINARY,
 646                          ((offset>>8) & 0xff), (offset & 0xff) , -1, NULL,
 647                          n, &buffer, &bufferlen);
 648       if ( SW_EXACT_LENGTH_P(sw) )
 649         {
 650           n = (sw & 0x00ff);
 651           sw = apdu_send_le (slot, 0x00, CMD_READ_BINARY,
 652                              ((offset>>8) & 0xff), (offset & 0xff) , -1, NULL,
 653                              n, &buffer, &bufferlen);
 654         }
 655
 656       if (*result && sw == SW_BAD_P0_P1)
 657         {
 658           /* Bad Parameter means that the offset is outside of the
 659              EF. When reading all data we take this as an indication
 660              for EOF.  */
 661           break;
 662         }
 663
 664       if (sw != SW_SUCCESS && sw != SW_EOF_REACHED)
 665         {
 666           /* Make sure that pending buffers are released. */
 667           xfree (buffer);
 668           xfree (*result);
 669           *result = NULL;
 670           *resultlen = 0;
 671           return map_sw (sw);
 672         }
 673       if (*result) /* Need to extend the buffer. */
 674         {
 675           unsigned char *p = xtryrealloc (*result, *resultlen + bufferlen);
 676           if (!p)
 677             {
 678               gpg_error_t err = gpg_error_from_syserror ();
 679               xfree (buffer);
 680               xfree (*result);
 681               *result = NULL;
 682               *resultlen = 0;
 683               return err;
 684             }
 685           *result = p;
 686           memcpy (*result + *resultlen, buffer, bufferlen);
 687           *resultlen += bufferlen;
 688           xfree (buffer);
 689           buffer = NULL;
 690         }
 691       else /* Transfer the buffer into our result. */
 692         {
 693           *result = buffer;
 694           *resultlen = bufferlen;
 695         }
 696       offset += bufferlen;
 697       if (offset > 32767)
 698         break; /* We simply truncate the result for too large
 699                   files. */
 700       if (nmax > bufferlen)
 701         nmax -= bufferlen;
 702       else
 703         nmax = 0;
 704     }
 705   while ((read_all && sw != SW_EOF_REACHED) || (!read_all && nmax));
 706
 707   return 0;
 708 }
 709
 710 /* Perform a READ RECORD command. RECNO gives the record number to
 711    read with 0 indicating the current record.  RECCOUNT must be 1 (not
 712    all cards support reading of more than one record).  SHORT_EF
 713    should be 0 to read the current EF or contain a short EF. The
 714    result is stored in a newly allocated buffer at the address passed
 715    by RESULT.  Returns the length of this data at the address of
 716    RESULTLEN. */
 717 gpg_error_t
 718 iso7816_read_record (int slot, int recno, int reccount, int short_ef,
 719                      unsigned char **result, size_t *resultlen)
 720 {
 721   int sw;
 722   unsigned char *buffer;
 723   size_t bufferlen;
 724
 725   if (!result || !resultlen)
 726     return gpg_error (GPG_ERR_INV_VALUE);
 727   *result = NULL;
 728   *resultlen = 0;
 729
 730   /* We can only encode 15 bits in p0,p1 to indicate an offset. Thus
 731      we check for this limit. */
 732   if (recno < 0 || recno > 255 || reccount != 1
 733       || short_ef < 0 || short_ef > 254 )
 734     return gpg_error (GPG_ERR_INV_VALUE);
 735
 736   buffer = NULL;
 737   bufferlen = 0;
 738   /* Fixme: Either the ccid driver or the TCOS cards have problems
 739      with an Le of 0. */
 740   sw = apdu_send_le (slot, 0x00, CMD_READ_RECORD,
 741                      recno,
 742                      short_ef? short_ef : 0x04,
 743                      -1, NULL,
 744                      254, &buffer, &bufferlen);
 745
 746   if (sw != SW_SUCCESS && sw != SW_EOF_REACHED)
 747     {
 748       /* Make sure that pending buffers are released. */
 749       xfree (buffer);
 750       xfree (*result);
 751       *result = NULL;
 752       *resultlen = 0;
 753       return map_sw (sw);
 754     }
 755   *result = buffer;
 756   *resultlen = bufferlen;
 757
 758   return 0;
 759 }
 760