sm/call-agent.c

   1 /* call-agent.c - divert operations to the agent
   2  *      Copyright (C) 2001, 2002, 2003, 2005 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 2 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, write to the Free Software
  18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
  19  * USA.
  20  */
  21
  22 #include <config.h>
  23 #include <stdio.h>
  24 #include <stdlib.h>
  25 #include <string.h>
  26 #include <errno.h>
  27 #include <unistd.h>
  28 #include <time.h>
  29 #include <assert.h>
  30 #ifdef HAVE_LOCALE_H
  31 #include <locale.h>
  32 #endif
  33
  34 #include "gpgsm.h"
  35 #include <gcrypt.h>
  36 #include <assuan.h>
  37 #include "i18n.h"
  38 #include "asshelp.h"
  39 #include "keydb.h" /* fixme: Move this to import.c */
  40 #include "../common/membuf.h"
  41
  42
  43 static assuan_context_t agent_ctx = NULL;
  44 static int force_pipe_server = 0;
  45
  46 struct cipher_parm_s
  47 {
  48   assuan_context_t ctx;
  49   const unsigned char *ciphertext;
  50   size_t ciphertextlen;
  51 };
  52
  53 struct genkey_parm_s
  54 {
  55   assuan_context_t ctx;
  56   const unsigned char *sexp;
  57   size_t sexplen;
  58 };
  59
  60 struct learn_parm_s
  61 {
  62   int error;
  63   assuan_context_t ctx;
  64   membuf_t *data;
  65 };
  66
  67
  68 \f
  69 /* Try to connect to the agent via socket or fork it off and work by
  70    pipes.  Handle the server's initial greeting */
  71 static int
  72 start_agent (ctrl_t ctrl)
  73 {
  74   int rc = 0;
  75   char *infostr, *p;
  76   assuan_context_t ctx;
  77
  78   if (agent_ctx)
  79     return 0; /* fixme: We need a context for each thread or serialize
  80                  the access to the agent (which is suitable given that
  81                  the agent is not MT. */
  82
  83   infostr = force_pipe_server? NULL : getenv ("GPG_AGENT_INFO");
  84   if (!infostr || !*infostr)
  85     {
  86       const char *pgmname;
  87       const char *argv[3];
  88       char *sockname;
  89       int no_close_list[3];
  90       int i;
  91
  92       /* First check whether we can connect at the standard
  93          socket.  */
  94       sockname = make_filename (opt.homedir, "S.gpg-agent", NULL);
  95       rc = assuan_socket_connect (&ctx, sockname, 0);
  96       xfree (sockname);
  97
  98       if (rc)
  99         {
 100           /* With no success start a new server.  */
 101           if (opt.verbose)
 102             log_info (_("no running gpg-agent - starting one\n"));
 103
 104           gpgsm_status (ctrl, STATUS_PROGRESS, "starting_agent ? 0 0");
 105
 106           if (fflush (NULL))
 107             {
 108               gpg_error_t tmperr = gpg_error (gpg_err_code_from_errno (errno));
 109               log_error ("error flushing pending output: %s\n",
 110                          strerror (errno));
 111               return tmperr;
 112             }
 113
 114           if (!opt.agent_program || !*opt.agent_program)
 115             opt.agent_program = GNUPG_DEFAULT_AGENT;
 116           if ( !(pgmname = strrchr (opt.agent_program, '/')))
 117             pgmname = opt.agent_program;
 118           else
 119             pgmname++;
 120
 121           argv[0] = pgmname;
 122           argv[1] = "--server";
 123           argv[2] = NULL;
 124
 125           i=0;
 126           if (log_get_fd () != -1)
 127             no_close_list[i++] = log_get_fd ();
 128           no_close_list[i++] = fileno (stderr);
 129           no_close_list[i] = -1;
 130
 131           /* Connect to the agent and perform initial handshaking. */
 132           rc = assuan_pipe_connect (&ctx, opt.agent_program, argv,
 133                                     no_close_list);
 134         }
 135     }
 136   else
 137     {
 138       int prot;
 139       int pid;
 140
 141       infostr = xstrdup (infostr);
 142       if ( !(p = strchr (infostr, PATHSEP_C)) || p == infostr)
 143         {
 144           log_error (_("malformed GPG_AGENT_INFO environment variable\n"));
 145           xfree (infostr);
 146           force_pipe_server = 1;
 147           return start_agent (ctrl);
 148         }
 149       *p++ = 0;
 150       pid = atoi (p);
 151       while (*p && *p != PATHSEP_C)
 152         p++;
 153       prot = *p? atoi (p+1) : 0;
 154       if (prot != 1)
 155         {
 156           log_error (_("gpg-agent protocol version %d is not supported\n"),
 157                      prot);
 158           xfree (infostr);
 159           force_pipe_server = 1;
 160           return start_agent (ctrl);
 161         }
 162
 163       rc = assuan_socket_connect (&ctx, infostr, pid);
 164       xfree (infostr);
 165       if (gpg_err_code (rc) == GPG_ERR_ASS_CONNECT_FAILED)
 166         {
 167           log_error (_("can't connect to the agent - trying fall back\n"));
 168           force_pipe_server = 1;
 169           return start_agent (ctrl);
 170         }
 171     }
 172
 173   if (rc)
 174     {
 175       log_error ("can't connect to the agent: %s\n", gpg_strerror (rc));
 176       return gpg_error (GPG_ERR_NO_AGENT);
 177     }
 178   agent_ctx = ctx;
 179
 180   if (DBG_ASSUAN)
 181     log_debug ("connection to agent established\n");
 182
 183   rc = assuan_transact (agent_ctx, "RESET", NULL, NULL, NULL, NULL, NULL, NULL);
 184   if (rc)
 185     return rc;
 186
 187   return send_pinentry_environment (agent_ctx, GPG_ERR_SOURCE_DEFAULT,
 188                                     opt.display, opt.ttyname, opt.ttytype,
 189                                     opt.lc_ctype, opt.lc_messages);
 190 }
 191
 192
 193 static int
 194 membuf_data_cb (void *opaque, const void *buffer, size_t length)
 195 {
 196   membuf_t *data = opaque;
 197
 198   if (buffer)
 199     put_membuf (data, buffer, length);
 200   return 0;
 201 }
 202
 203
 204
 205 \f
 206 /* Call the agent to do a sign operation using the key identified by
 207    the hex string KEYGRIP. */
 208 int
 209 gpgsm_agent_pksign (ctrl_t ctrl, const char *keygrip, const char *desc,
 210                     unsigned char *digest, size_t digestlen, int digestalgo,
 211                     unsigned char **r_buf, size_t *r_buflen )
 212 {
 213   int rc, i;
 214   char *p, line[ASSUAN_LINELENGTH];
 215   membuf_t data;
 216   size_t len;
 217
 218   *r_buf = NULL;
 219   rc = start_agent (ctrl);
 220   if (rc)
 221     return rc;
 222
 223   if (digestlen*2 + 50 > DIM(line))
 224     return gpg_error (GPG_ERR_GENERAL);
 225
 226   rc = assuan_transact (agent_ctx, "RESET", NULL, NULL, NULL, NULL, NULL, NULL);
 227   if (rc)
 228     return rc;
 229
 230   snprintf (line, DIM(line)-1, "SIGKEY %s", keygrip);
 231   line[DIM(line)-1] = 0;
 232   rc = assuan_transact (agent_ctx, line, NULL, NULL, NULL, NULL, NULL, NULL);
 233   if (rc)
 234     return rc;
 235
 236   if (desc)
 237     {
 238       snprintf (line, DIM(line)-1, "SETKEYDESC %s", desc);
 239       line[DIM(line)-1] = 0;
 240       rc = assuan_transact (agent_ctx, line,
 241                             NULL, NULL, NULL, NULL, NULL, NULL);
 242       if (rc)
 243         return rc;
 244     }
 245
 246   sprintf (line, "SETHASH %d ", digestalgo);
 247   p = line + strlen (line);
 248   for (i=0; i < digestlen ; i++, p += 2 )
 249     sprintf (p, "%02X", digest[i]);
 250   rc = assuan_transact (agent_ctx, line, NULL, NULL, NULL, NULL, NULL, NULL);
 251   if (rc)
 252     return rc;
 253
 254   init_membuf (&data, 1024);
 255   rc = assuan_transact (agent_ctx, "PKSIGN",
 256                         membuf_data_cb, &data, NULL, NULL, NULL, NULL);
 257   if (rc)
 258     {
 259       xfree (get_membuf (&data, &len));
 260       return rc;
 261     }
 262   *r_buf = get_membuf (&data, r_buflen);
 263
 264   if (!gcry_sexp_canon_len (*r_buf, *r_buflen, NULL, NULL))
 265     {
 266       xfree (*r_buf); *r_buf = NULL;
 267       return gpg_error (GPG_ERR_INV_VALUE);
 268     }
 269
 270   return *r_buf? 0 : out_of_core ();
 271 }
 272
 273
 274
 275 \f
 276 /* Handle a CIPHERTEXT inquiry.  Note, we only send the data,
 277    assuan_transact talkes care of flushing and writing the end */
 278 static int
 279 inq_ciphertext_cb (void *opaque, const char *keyword)
 280 {
 281   struct cipher_parm_s *parm = opaque;
 282   int rc;
 283
 284   assuan_begin_confidential (parm->ctx);
 285   rc = assuan_send_data (parm->ctx, parm->ciphertext, parm->ciphertextlen);
 286   assuan_end_confidential (parm->ctx);
 287   return rc;
 288 }
 289
 290
 291 /* Call the agent to do a decrypt operation using the key identified by
 292    the hex string KEYGRIP. */
 293 int
 294 gpgsm_agent_pkdecrypt (ctrl_t ctrl, const char *keygrip, const char *desc,
 295                        ksba_const_sexp_t ciphertext,
 296                        char **r_buf, size_t *r_buflen )
 297 {
 298   int rc;
 299   char line[ASSUAN_LINELENGTH];
 300   membuf_t data;
 301   struct cipher_parm_s cipher_parm;
 302   size_t n, len;
 303   char *p, *buf, *endp;
 304   size_t ciphertextlen;
 305
 306   if (!keygrip || strlen(keygrip) != 40 || !ciphertext || !r_buf || !r_buflen)
 307     return gpg_error (GPG_ERR_INV_VALUE);
 308   *r_buf = NULL;
 309
 310   ciphertextlen = gcry_sexp_canon_len (ciphertext, 0, NULL, NULL);
 311   if (!ciphertextlen)
 312     return gpg_error (GPG_ERR_INV_VALUE);
 313
 314   rc = start_agent (ctrl);
 315   if (rc)
 316     return rc;
 317
 318   rc = assuan_transact (agent_ctx, "RESET", NULL, NULL, NULL, NULL, NULL, NULL);
 319   if (rc)
 320     return rc;
 321
 322   assert ( DIM(line) >= 50 );
 323   snprintf (line, DIM(line)-1, "SETKEY %s", keygrip);
 324   line[DIM(line)-1] = 0;
 325   rc = assuan_transact (agent_ctx, line, NULL, NULL, NULL, NULL, NULL, NULL);
 326   if (rc)
 327     return rc;
 328
 329   if (desc)
 330     {
 331       snprintf (line, DIM(line)-1, "SETKEYDESC %s", desc);
 332       line[DIM(line)-1] = 0;
 333       rc = assuan_transact (agent_ctx, line,
 334                             NULL, NULL, NULL, NULL, NULL, NULL);
 335       if (rc)
 336         return rc;
 337     }
 338
 339   init_membuf (&data, 1024);
 340   cipher_parm.ctx = agent_ctx;
 341   cipher_parm.ciphertext = ciphertext;
 342   cipher_parm.ciphertextlen = ciphertextlen;
 343   rc = assuan_transact (agent_ctx, "PKDECRYPT",
 344                         membuf_data_cb, &data,
 345                         inq_ciphertext_cb, &cipher_parm, NULL, NULL);
 346   if (rc)
 347     {
 348       xfree (get_membuf (&data, &len));
 349       return rc;
 350     }
 351
 352   put_membuf (&data, "", 1); /* Make sure it is 0 terminated. */
 353   buf = get_membuf (&data, &len);
 354   if (!buf)
 355     return gpg_error (GPG_ERR_ENOMEM);
 356   assert (len); /* (we forced Nul termination.)  */
 357
 358   if (*buf == '(')
 359     {
 360       if (len < 13 || memcmp (buf, "(5:value", 8) ) /* "(5:valueN:D)\0" */
 361         return gpg_error (GPG_ERR_INV_SEXP);
 362       len -= 11;   /* Count only the data of the second part. */
 363       p = buf + 8; /* Skip leading parenthesis and the value tag. */
 364     }
 365   else
 366     {
 367       /* For compatibility with older gpg-agents handle the old style
 368          incomplete S-exps. */
 369       len--;      /* Do not count the Nul. */
 370       p = buf;
 371     }
 372
 373   n = strtoul (p, &endp, 10);
 374   if (!n || *endp != ':')
 375     return gpg_error (GPG_ERR_INV_SEXP);
 376   endp++;
 377   if (endp-p+n > len)
 378     return gpg_error (GPG_ERR_INV_SEXP); /* Oops: Inconsistent S-Exp. */
 379
 380   memmove (buf, endp, n);
 381
 382   *r_buflen = n;
 383   *r_buf = buf;
 384   return 0;
 385 }
 386
 387
 388
 389
 390 \f
 391 /* Handle a KEYPARMS inquiry.  Note, we only send the data,
 392    assuan_transact takes care of flushing and writing the end */
 393 static int
 394 inq_genkey_parms (void *opaque, const char *keyword)
 395 {
 396   struct genkey_parm_s *parm = opaque;
 397   int rc;
 398
 399   rc = assuan_send_data (parm->ctx, parm->sexp, parm->sexplen);
 400   return rc;
 401 }
 402
 403
 404 \f
 405 /* Call the agent to generate a newkey */
 406 int
 407 gpgsm_agent_genkey (ctrl_t ctrl,
 408                     ksba_const_sexp_t keyparms, ksba_sexp_t *r_pubkey)
 409 {
 410   int rc;
 411   struct genkey_parm_s gk_parm;
 412   membuf_t data;
 413   size_t len;
 414   unsigned char *buf;
 415
 416   *r_pubkey = NULL;
 417   rc = start_agent (ctrl);
 418   if (rc)
 419     return rc;
 420
 421   rc = assuan_transact (agent_ctx, "RESET", NULL, NULL, NULL, NULL, NULL, NULL);
 422   if (rc)
 423     return rc;
 424
 425   init_membuf (&data, 1024);
 426   gk_parm.ctx = agent_ctx;
 427   gk_parm.sexp = keyparms;
 428   gk_parm.sexplen = gcry_sexp_canon_len (keyparms, 0, NULL, NULL);
 429   if (!gk_parm.sexplen)
 430     return gpg_error (GPG_ERR_INV_VALUE);
 431   rc = assuan_transact (agent_ctx, "GENKEY",
 432                         membuf_data_cb, &data,
 433                         inq_genkey_parms, &gk_parm, NULL, NULL);
 434   if (rc)
 435     {
 436       xfree (get_membuf (&data, &len));
 437       return rc;
 438     }
 439   buf = get_membuf (&data, &len);
 440   if (!buf)
 441     return gpg_error (GPG_ERR_ENOMEM);
 442   if (!gcry_sexp_canon_len (buf, len, NULL, NULL))
 443     {
 444       xfree (buf);
 445       return gpg_error (GPG_ERR_INV_SEXP);
 446     }
 447   *r_pubkey = buf;
 448   return 0;
 449 }
 450
 451 \f
 452 /* Call the agent to read the public key part for a given keygrip.  */
 453 int
 454 gpgsm_agent_readkey (ctrl_t ctrl, const char *hexkeygrip,
 455                      ksba_sexp_t *r_pubkey)
 456 {
 457   int rc;
 458   membuf_t data;
 459   size_t len;
 460   unsigned char *buf;
 461   char line[ASSUAN_LINELENGTH];
 462
 463   *r_pubkey = NULL;
 464   rc = start_agent (ctrl);
 465   if (rc)
 466     return rc;
 467
 468   rc = assuan_transact (agent_ctx, "RESET",NULL, NULL, NULL, NULL, NULL, NULL);
 469   if (rc)
 470     return rc;
 471
 472   snprintf (line, DIM(line)-1, "READKEY %s", hexkeygrip);
 473   line[DIM(line)-1] = 0;
 474
 475   init_membuf (&data, 1024);
 476   rc = assuan_transact (agent_ctx, line,
 477                         membuf_data_cb, &data,
 478                         NULL, NULL, NULL, NULL);
 479   if (rc)
 480     {
 481       xfree (get_membuf (&data, &len));
 482       return rc;
 483     }
 484   buf = get_membuf (&data, &len);
 485   if (!buf)
 486     return gpg_error (GPG_ERR_ENOMEM);
 487   if (!gcry_sexp_canon_len (buf, len, NULL, NULL))
 488     {
 489       xfree (buf);
 490       return gpg_error (GPG_ERR_INV_SEXP);
 491     }
 492   *r_pubkey = buf;
 493   return 0;
 494 }
 495
 496 \f
 497 /* Ask the agent whether the certificate is in the list of trusted
 498    keys */
 499 int
 500 gpgsm_agent_istrusted (ctrl_t ctrl, ksba_cert_t cert)
 501 {
 502   int rc;
 503   char *fpr;
 504   char line[ASSUAN_LINELENGTH];
 505
 506   rc = start_agent (ctrl);
 507   if (rc)
 508     return rc;
 509
 510   fpr = gpgsm_get_fingerprint_hexstring (cert, GCRY_MD_SHA1);
 511   if (!fpr)
 512     {
 513       log_error ("error getting the fingerprint\n");
 514       return gpg_error (GPG_ERR_GENERAL);
 515     }
 516
 517   snprintf (line, DIM(line)-1, "ISTRUSTED %s", fpr);
 518   line[DIM(line)-1] = 0;
 519   xfree (fpr);
 520
 521   rc = assuan_transact (agent_ctx, line, NULL, NULL, NULL, NULL, NULL, NULL);
 522   return rc;
 523 }
 524
 525 /* Ask the agent to mark CERT as a trusted Root-CA one */
 526 int
 527 gpgsm_agent_marktrusted (ctrl_t ctrl, ksba_cert_t cert)
 528 {
 529   int rc;
 530   char *fpr, *dn;
 531   char line[ASSUAN_LINELENGTH];
 532
 533   rc = start_agent (ctrl);
 534   if (rc)
 535     return rc;
 536
 537   fpr = gpgsm_get_fingerprint_hexstring (cert, GCRY_MD_SHA1);
 538   if (!fpr)
 539     {
 540       log_error ("error getting the fingerprint\n");
 541       return gpg_error (GPG_ERR_GENERAL);
 542     }
 543
 544   dn = ksba_cert_get_issuer (cert, 0);
 545   if (!dn)
 546     {
 547       xfree (fpr);
 548       return gpg_error (GPG_ERR_GENERAL);
 549     }
 550   snprintf (line, DIM(line)-1, "MARKTRUSTED %s S %s", fpr, dn);
 551   line[DIM(line)-1] = 0;
 552   ksba_free (dn);
 553   xfree (fpr);
 554
 555   rc = assuan_transact (agent_ctx, line, NULL, NULL, NULL, NULL, NULL, NULL);
 556   return rc;
 557 }
 558
 559
 560 \f
 561 /* Ask the agent whether the a corresponding secret key is available
 562    for the given keygrip */
 563 int
 564 gpgsm_agent_havekey (ctrl_t ctrl, const char *hexkeygrip)
 565 {
 566   int rc;
 567   char line[ASSUAN_LINELENGTH];
 568
 569   rc = start_agent (ctrl);
 570   if (rc)
 571     return rc;
 572
 573   if (!hexkeygrip || strlen (hexkeygrip) != 40)
 574     return gpg_error (GPG_ERR_INV_VALUE);
 575
 576   snprintf (line, DIM(line)-1, "HAVEKEY %s", hexkeygrip);
 577   line[DIM(line)-1] = 0;
 578
 579   rc = assuan_transact (agent_ctx, line, NULL, NULL, NULL, NULL, NULL, NULL);
 580   return rc;
 581 }
 582
 583 \f
 584 static int
 585 learn_cb (void *opaque, const void *buffer, size_t length)
 586 {
 587   struct learn_parm_s *parm = opaque;
 588   size_t len;
 589   char *buf;
 590   ksba_cert_t cert;
 591   int rc;
 592
 593   if (parm->error)
 594     return 0;
 595
 596   if (buffer)
 597     {
 598       put_membuf (parm->data, buffer, length);
 599       return 0;
 600     }
 601   /* END encountered - process what we have */
 602   buf = get_membuf (parm->data, &len);
 603   if (!buf)
 604     {
 605       parm->error = gpg_error (GPG_ERR_ENOMEM);
 606       return 0;
 607     }
 608
 609
 610   /* FIXME: this should go into import.c */
 611   rc = ksba_cert_new (&cert);
 612   if (rc)
 613     {
 614       parm->error = rc;
 615       return 0;
 616     }
 617   rc = ksba_cert_init_from_mem (cert, buf, len);
 618   if (rc)
 619     {
 620       log_error ("failed to parse a certificate: %s\n", gpg_strerror (rc));
 621       ksba_cert_release (cert);
 622       parm->error = rc;
 623       return 0;
 624     }
 625
 626   rc = gpgsm_basic_cert_check (cert);
 627   if (gpg_err_code (rc) == GPG_ERR_MISSING_CERT)
 628     { /* For later use we store it in the ephemeral database. */
 629       log_info ("issuer certificate missing - storing as ephemeral\n");
 630       keydb_store_cert (cert, 1, NULL);
 631     }
 632   else if (rc)
 633     log_error ("invalid certificate: %s\n", gpg_strerror (rc));
 634   else
 635     {
 636       int existed;
 637
 638       if (!keydb_store_cert (cert, 0, &existed))
 639         {
 640           if (opt.verbose > 1 && existed)
 641             log_info ("certificate already in DB\n");
 642           else if (opt.verbose && !existed)
 643             log_info ("certificate imported\n");
 644         }
 645     }
 646
 647   ksba_cert_release (cert);
 648   init_membuf (parm->data, 4096);
 649   return 0;
 650 }
 651
 652 /* Call the agent to learn about a smartcard */
 653 int
 654 gpgsm_agent_learn (ctrl_t ctrl)
 655 {
 656   int rc;
 657   struct learn_parm_s learn_parm;
 658   membuf_t data;
 659   size_t len;
 660
 661   rc = start_agent (ctrl);
 662   if (rc)
 663     return rc;
 664
 665   init_membuf (&data, 4096);
 666   learn_parm.error = 0;
 667   learn_parm.ctx = agent_ctx;
 668   learn_parm.data = &data;
 669   rc = assuan_transact (agent_ctx, "LEARN --send",
 670                         learn_cb, &learn_parm,
 671                         NULL, NULL, NULL, NULL);
 672   xfree (get_membuf (&data, &len));
 673   if (rc)
 674     return rc;
 675   return learn_parm.error;
 676 }
 677
 678 \f
 679 /* Ask the agent to change the passphrase of the key identified by
 680    HEXKEYGRIP. If DESC is not NULL, display instead of the default
 681    description message. */
 682 int
 683 gpgsm_agent_passwd (ctrl_t ctrl, const char *hexkeygrip, const char *desc)
 684 {
 685   int rc;
 686   char line[ASSUAN_LINELENGTH];
 687
 688   rc = start_agent (ctrl);
 689   if (rc)
 690     return rc;
 691
 692   if (!hexkeygrip || strlen (hexkeygrip) != 40)
 693     return gpg_error (GPG_ERR_INV_VALUE);
 694
 695   if (desc)
 696     {
 697       snprintf (line, DIM(line)-1, "SETKEYDESC %s", desc);
 698       line[DIM(line)-1] = 0;
 699       rc = assuan_transact (agent_ctx, line,
 700                             NULL, NULL, NULL, NULL, NULL, NULL);
 701       if (rc)
 702         return rc;
 703     }
 704
 705   snprintf (line, DIM(line)-1, "PASSWD %s", hexkeygrip);
 706   line[DIM(line)-1] = 0;
 707
 708   rc = assuan_transact (agent_ctx, line, NULL, NULL, NULL, NULL, NULL, NULL);
 709   return rc;
 710 }
 711
 712
 713 \f
 714 /* Ask the agent to pop up a confirmation dialog with the text DESC
 715    and an okay and cancel button.  */
 716 gpg_error_t
 717 gpgsm_agent_get_confirmation (ctrl_t ctrl, const char *desc)
 718 {
 719   int rc;
 720   char line[ASSUAN_LINELENGTH];
 721
 722   rc = start_agent (ctrl);
 723   if (rc)
 724     return rc;
 725
 726   snprintf (line, DIM(line)-1, "GET_CONFIRMATION %s", desc);
 727   line[DIM(line)-1] = 0;
 728
 729   rc = assuan_transact (agent_ctx, line, NULL, NULL, NULL, NULL, NULL, NULL);
 730   return rc;
 731 }