gnupg/sm/call-dirmngr.c

/* call-dirmngr.c - communication with the dromngr 
 *	Copyright (C) 2002, 2003, 2005 Free Software Foundation, Inc.
 *
 * This file is part of GnuPG.
 *
 * GnuPG is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
 * GnuPG is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, see <http://www.gnu.org/licenses/>.
 */

#include <config.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <unistd.h> 
#include <time.h>
#include <assert.h>
#include <ctype.h>

#include "gpgsm.h"
#include <gcrypt.h>
#include <assuan.h>

#include "i18n.h"
#include "keydb.h"


struct membuf {
  size_t len;
  size_t size;
  char *buf;
  int out_of_core;
};



static assuan_context_t dirmngr_ctx = NULL;
static int force_pipe_server = 0;

struct inq_certificate_parm_s {
  assuan_context_t ctx;
  ksba_cert_t cert;
  ksba_cert_t issuer_cert;
};

struct isvalid_status_parm_s {
  ctrl_t ctrl;
  int seen;
  unsigned char fpr[20];
};


struct lookup_parm_s {
  ctrl_t ctrl;
  assuan_context_t ctx;
  void (*cb)(void *, ksba_cert_t);
  void *cb_value;
  struct membuf data;
  int error;
};

struct run_command_parm_s {
  assuan_context_t ctx;
};


/* A simple implementation of a dynamic buffer.  Use init_membuf() to
   create a buffer, put_membuf to append bytes and get_membuf to
   release and return the buffer.  Allocation errors are detected but
   only returned at the final get_membuf(), this helps not to clutter
   the code with out of core checks.  */

static void
init_membuf (struct membuf *mb, int initiallen)
{
  mb->len = 0;
  mb->size = initiallen;
  mb->out_of_core = 0;
  mb->buf = xtrymalloc (initiallen);
  if (!mb->buf)
      mb->out_of_core = 1;
}

static void
put_membuf (struct membuf *mb, const void *buf, size_t len)
{
  if (mb->out_of_core)
    return;

  if (mb->len + len >= mb->size)
    {
      char *p;
      
      mb->size += len + 1024;
      p = xtryrealloc (mb->buf, mb->size);
      if (!p)
        {
          mb->out_of_core = 1;
          return;
        }
      mb->buf = p;
    }
  memcpy (mb->buf + mb->len, buf, len);
  mb->len += len;
}

static void *
get_membuf (struct membuf *mb, size_t *len)
{
  char *p;

  if (mb->out_of_core)
    {
      xfree (mb->buf);
      mb->buf = NULL;
      return NULL;
    }

  p = mb->buf;
  *len = mb->len;
  mb->buf = NULL;
  mb->out_of_core = 1; /* don't allow a reuse */
  return p;
}





/* Try to connect to the agent via socket or fork it off and work by
   pipes.  Handle the server's initial greeting */
static int
start_dirmngr (void)
{
  int rc;
  char *infostr, *p;
  assuan_context_t ctx;
  int try_default = 0;

  if (dirmngr_ctx)
    return 0; /* fixme: We need a context for each thread or serialize
                 the access to the dirmngr */
  /* Note: if you change this to multiple connections, you also need
     to take care of the implicit option sending caching. */

#ifdef HAVE_W32_SYSTEM
  infostr = NULL;
  opt.prefer_system_dirmngr = 1;
#else
  infostr = force_pipe_server? NULL : getenv ("DIRMNGR_INFO");
#endif /*HAVE_W32_SYSTEM*/
  if (infostr && !*infostr)
    infostr = NULL;
  else if (infostr)
    infostr = xstrdup (infostr);

  if (opt.prefer_system_dirmngr && !force_pipe_server && !infostr)
    {
      infostr = xstrdup (dirmngr_socket_name ());
      try_default = 1;
    }
  if (!infostr)
    {
      const char *pgmname;
      const char *argv[3];
      int no_close_list[3];
      int i;

      if (!opt.dirmngr_program || !*opt.dirmngr_program)
        opt.dirmngr_program = gnupg_module_name (GNUPG_MODULE_NAME_DIRMNGR);
      if ( !(pgmname = strrchr (opt.dirmngr_program, '/')))
        pgmname = opt.dirmngr_program;
      else
        pgmname++;

      if (opt.verbose)
        log_info (_("no running dirmngr - starting `%s'\n"),
                  opt.dirmngr_program);
      
      if (fflush (NULL))
        {
          gpg_error_t tmperr = gpg_error (gpg_err_code_from_errno (errno));
          log_error ("error flushing pending output: %s\n", strerror (errno));
          return tmperr;
        }

      argv[0] = pgmname;
      argv[1] = "--server";
      argv[2] = NULL;

      i=0;
      if (log_get_fd () != -1)
        no_close_list[i++] = log_get_fd ();
      no_close_list[i++] = fileno (stderr);
      no_close_list[i] = -1;

      /* connect to the agent and perform initial handshaking */
      rc = assuan_pipe_connect (&ctx, opt.dirmngr_program, argv,
                                no_close_list);
    }
  else
    {
      int prot;
      int pid;

      if (!try_default)
        {
          if ( !(p = strchr (infostr, PATHSEP_C)) || p == infostr)
            {
              log_error (_("malformed DIRMNGR_INFO environment variable\n"));
              xfree (infostr);
              force_pipe_server = 1;
              return start_dirmngr ();
            }
          *p++ = 0;
          pid = atoi (p);
          while (*p && *p != PATHSEP_C)
            p++;
          prot = *p? atoi (p+1) : 0;
          if (prot != 1)
            {
              log_error (_("dirmngr protocol version %d is not supported\n"),
                         prot);
              xfree (infostr);
              force_pipe_server = 1;
              return start_dirmngr ();
            }
        }
      else
        pid = -1;

      rc = assuan_socket_connect (&ctx, infostr, pid);
#ifdef HAVE_W32_SYSTEM
      if (rc)
        log_debug ("connecting dirmngr at `%s' failed\n", infostr);
#endif

      xfree (infostr);
#ifndef HAVE_W32_SYSTEM
      if (gpg_err_code (rc) == GPG_ERR_ASS_CONNECT_FAILED)
        {
          log_error (_("can't connect to the dirmngr - trying fall back\n"));
          force_pipe_server = 1;
          return start_dirmngr ();
        }
#endif /*!HAVE_W32_SYSTEM*/
    }

  if (rc)
    {
      log_error ("can't connect to the dirmngr: %s\n", gpg_strerror (rc));
      return gpg_error (GPG_ERR_NO_DIRMNGR);
    }
  dirmngr_ctx = ctx;

  if (DBG_ASSUAN)
    log_debug ("connection to dirmngr established\n");
  return 0;
}



/* Handle a SENDCERT inquiry. */
static int
inq_certificate (void *opaque, const char *line)
{
  struct inq_certificate_parm_s *parm = opaque;
  int rc;
  const unsigned char *der;
  size_t derlen;
  int issuer_mode = 0;
  ksba_sexp_t ski = NULL;

  if (!strncmp (line, "SENDCERT", 8) && (line[8] == ' ' || !line[8]))
    {
      line += 8;
    }
  else if (!strncmp (line, "SENDCERT_SKI", 12) && (line[12]==' ' || !line[12]))
    {
      size_t n;

      /* Send a certificate where a sourceKeyIdentifier is included. */
      line += 12;
      while (*line == ' ')
        line++;
      ski = make_simple_sexp_from_hexstr (line, &n);
      line += n;
      while (*line == ' ')
        line++;
    }
  else if (!strncmp (line, "SENDISSUERCERT", 14)
           && (line[14] == ' ' || !line[14]))
    {
      line += 14;
      issuer_mode = 1;
    }
  else
    {
      log_error ("unsupported inquiry `%s'\n", line);
      return gpg_error (GPG_ERR_ASS_UNKNOWN_INQUIRE);
    }

  if (!*line)
    { /* Send the current certificate. */
      der = ksba_cert_get_image (issuer_mode? parm->issuer_cert : parm->cert,
                                 &derlen);
      if (!der)
        rc = gpg_error (GPG_ERR_INV_CERT_OBJ);
      else
        rc = assuan_send_data (parm->ctx, der, derlen);
    }
  else if (issuer_mode)
    {
      log_error ("sending specific issuer certificate back "
                 "is not yet implemented\n");
      rc = gpg_error (GPG_ERR_ASS_UNKNOWN_INQUIRE);
    }
  else 
    { /* Send the given certificate. */
      int err;
      ksba_cert_t cert;


      err = gpgsm_find_cert (line, ski, &cert);
      if (err)
        {
          log_error ("certificate not found: %s\n", gpg_strerror (err));
          rc = gpg_error (GPG_ERR_NOT_FOUND);
        }
      else
        {
          der = ksba_cert_get_image (cert, &derlen);
          if (!der)
            rc = gpg_error (GPG_ERR_INV_CERT_OBJ);
          else
            rc = assuan_send_data (parm->ctx, der, derlen);
          ksba_cert_release (cert);
        }
    }

  xfree (ski);
  return rc; 
}


/* Take a 20 byte hexencoded string and put it into the the provided
   20 byte buffer FPR in binary format. */
static int
unhexify_fpr (const char *hexstr, unsigned char *fpr)
{
  const char *s;
  int n;

  for (s=hexstr, n=0; hexdigitp (s); s++, n++)
    ;
  if (*s || (n != 40))
    return 0; /* no fingerprint (invalid or wrong length). */
  n /= 2;
  for (s=hexstr, n=0; *s; s += 2, n++)
    fpr[n] = xtoi_2 (s);
  return 1; /* okay */
}


static assuan_error_t
isvalid_status_cb (void *opaque, const char *line)
{
  struct isvalid_status_parm_s *parm = opaque;

  if (!strncmp (line, "PROGRESS", 8) && (line[8]==' ' || !line[8]))
    {
      if (parm->ctrl)
        {
          for (line += 8; *line == ' '; line++)
            ;
          if (gpgsm_status (parm->ctrl, STATUS_PROGRESS, line))
            return gpg_error (GPG_ERR_ASS_CANCELED);
        }
    }
  else if (!strncmp (line, "ONLY_VALID_IF_CERT_VALID", 24)
      && (line[24]==' ' || !line[24]))
    {
      parm->seen++;
      if (!line[24] || !unhexify_fpr (line+25, parm->fpr))
        parm->seen++; /* Bumb it to indicate an error. */
    }
  return 0;
}




/* Call the directory manager to check whether the certificate is valid
   Returns 0 for valid or usually one of the errors:

  GPG_ERR_CERTIFICATE_REVOKED
  GPG_ERR_NO_CRL_KNOWN
  GPG_ERR_CRL_TOO_OLD

  Values for USE_OCSP:
     0 = Do CRL check.
     1 = Do an OCSP check.
     2 = Do an OCSP check using only the default responder.
 */
int
gpgsm_dirmngr_isvalid (ctrl_t ctrl,
                       ksba_cert_t cert, ksba_cert_t issuer_cert, int use_ocsp)
{
  static int did_options;
  int rc;
  char *certid;
  char line[ASSUAN_LINELENGTH];
  struct inq_certificate_parm_s parm;
  struct isvalid_status_parm_s stparm;


  rc = start_dirmngr ();
  if (rc)
    return rc;

  if (use_ocsp)
    {
      certid = gpgsm_get_fingerprint_hexstring (cert, GCRY_MD_SHA1);
    }
  else
    {
      certid = gpgsm_get_certid (cert);
      if (!certid)
        {
          log_error ("error getting the certificate ID\n");
          return gpg_error (GPG_ERR_GENERAL);
        }
    }

  if (opt.verbose > 1)
    {
      char *fpr = gpgsm_get_fingerprint_string (cert, GCRY_MD_SHA1);
      log_info ("asking dirmngr about %s%s\n", fpr,
                use_ocsp? " (using OCSP)":"");
      xfree (fpr);
    }

  parm.ctx = dirmngr_ctx;
  parm.cert = cert;
  parm.issuer_cert = issuer_cert;

  stparm.ctrl = ctrl;
  stparm.seen = 0;
  memset (stparm.fpr, 0, 20);

  /* FIXME: If --disable-crl-checks has been set, we should pass an
     option to dirmngr, so that no fallback CRL check is done after an
     ocsp check.  It is not a problem right now as dirmngr does not
     fallback to CRL checking.  */

  /* It is sufficient to send the options only once because we have
     one connection per process only. */
  if (!did_options)
    {
      if (opt.force_crl_refresh)
        assuan_transact (dirmngr_ctx, "OPTION force-crl-refresh=1",
                         NULL, NULL, NULL, NULL, NULL, NULL);
      did_options = 1;
    }
  snprintf (line, DIM(line)-1, "ISVALID%s %s", 
            use_ocsp == 2? " --only-ocsp --force-default-responder":"",
            certid);
  line[DIM(line)-1] = 0;
  xfree (certid);

  rc = assuan_transact (dirmngr_ctx, line, NULL, NULL,
                        inq_certificate, &parm,
                        isvalid_status_cb, &stparm);
  if (opt.verbose > 1)
    log_info ("response of dirmngr: %s\n", rc? gpg_strerror (rc): "okay");
  rc = rc;

  if (!rc && stparm.seen)
    {
      /* Need to also check the certificate validity. */
      if (stparm.seen != 1)
        {
          log_error ("communication problem with dirmngr detected\n");
          rc = gpg_error (GPG_ERR_INV_CRL);
        }
      else
        {
          KEYDB_HANDLE kh;
          ksba_cert_t rspcert = NULL;

          /* Fixme: First try to get the certificate from the
             dirmngr's cache - it should be there. */
          kh = keydb_new (0);
          if (!kh)
            rc = gpg_error (GPG_ERR_ENOMEM);
          if (!rc)
            rc = keydb_search_fpr (kh, stparm.fpr);
          if (!rc)
            rc = keydb_get_cert (kh, &rspcert);
          if (rc)
            {
              log_error ("unable to find the certificate used "
                         "by the dirmngr: %s\n", gpg_strerror (rc));
              rc = gpg_error (GPG_ERR_INV_CRL);
            }
          keydb_release (kh);

          if (!rc)
            {
              rc = gpgsm_cert_use_ocsp_p (rspcert);
              if (rc)
                rc = gpg_error (GPG_ERR_INV_CRL);
              else
                {
                  /* Note the no_dirmngr flag: This avoids checking
                     this certificate over and over again. */
                  rc = gpgsm_validate_chain (ctrl, rspcert, "", NULL, 0, NULL, 
                                             VALIDATE_FLAG_NO_DIRMNGR, NULL);
                  if (rc)
                    {
                      log_error ("invalid certificate used for CRL/OCSP: %s\n",
                                 gpg_strerror (rc));
                      rc = gpg_error (GPG_ERR_INV_CRL);
                    }
                }
            }
          ksba_cert_release (rspcert);
        }
    }
  return rc;
}



/* Lookup helpers*/
static int
lookup_cb (void *opaque, const void *buffer, size_t length)
{
  struct lookup_parm_s *parm = opaque;
  size_t len;
  char *buf;
  ksba_cert_t cert;
  int rc;

  if (parm->error)
    return 0;

  if (buffer)
    {
      put_membuf (&parm->data, buffer, length);
      return 0;
    }
  /* END encountered - process what we have */
  buf = get_membuf (&parm->data, &len);
  if (!buf)
    {
      parm->error = gpg_error (GPG_ERR_ENOMEM);
      return 0;
    }

  rc = ksba_cert_new (&cert);
  if (rc)
    {
      parm->error = rc;
      return 0;
    }
  rc = ksba_cert_init_from_mem (cert, buf, len);
  if (rc)
    {
      log_error ("failed to parse a certificate: %s\n", gpg_strerror (rc));
    }
  else
    {
      parm->cb (parm->cb_value, cert);
    }

  ksba_cert_release (cert);
  init_membuf (&parm->data, 4096);
  return 0;
}

/* Return a properly escaped pattern from NAMES.  The only error
   return is NULL to indicate a malloc failure. */
static char *
pattern_from_strlist (strlist_t names)
{
  strlist_t sl;
  int n;
  const char *s;
  char *pattern, *p;

  for (n=0, sl=names; sl; sl = sl->next)
    {
      for (s=sl->d; *s; s++, n++)
	{
          if (*s == '%' || *s == ' ' || *s == '+')
            n += 2;
	}
      n++;
    }

  p = pattern = xtrymalloc (n+1);
  if (!pattern)
    return NULL;

  for (n=0, sl=names; sl; sl = sl->next)
    {
      for (s=sl->d; *s; s++)
        {
          switch (*s)
            {
            case '%':
              *p++ = '%';
              *p++ = '2';
              *p++ = '5';
              break;
            case ' ':
              *p++ = '%';
              *p++ = '2';
              *p++ = '0';
              break;
            case '+':
              *p++ = '%';
              *p++ = '2';
              *p++ = 'B';
              break;
            default:
              *p++ = *s;
              break;
            }
        }
      *p++ = ' ';
    }
  if (p == pattern)
    *pattern = 0; /* is empty */
  else
    p[-1] = '\0'; /* remove trailing blank */
  
  return pattern;
}

static int
lookup_status_cb (void *opaque, const char *line)
{
  struct lookup_parm_s *parm = opaque;

  if (!strncmp (line, "PROGRESS", 8) && (line[8]==' ' || !line[8]))
    {
      if (parm->ctrl)
        {
          for (line += 8; *line == ' '; line++)
            ;
          if (gpgsm_status (parm->ctrl, STATUS_PROGRESS, line))
            return gpg_error (GPG_ERR_ASS_CANCELED);
        }
    }
  else if (!strncmp (line, "TRUNCATED", 9) && (line[9]==' ' || !line[9]))
    {
      if (parm->ctrl)
        {
          for (line +=9; *line == ' '; line++)
            ;
          gpgsm_status (parm->ctrl, STATUS_TRUNCATED, line);
        }
    }
  return 0;
}


/* Run the Directroy Managers lookup command using the pattern
   compiled from the strings given in NAMES.  The caller must provide
   the callback CB which will be passed cert by cert.  Note that CTRL
   is optional. */
int 
gpgsm_dirmngr_lookup (ctrl_t ctrl, strlist_t names,
                      void (*cb)(void*, ksba_cert_t), void *cb_value)
{ 
  int rc;
  char *pattern;
  char line[ASSUAN_LINELENGTH];
  struct lookup_parm_s parm;
  size_t len;

  rc = start_dirmngr ();
  if (rc)
    return rc;

  pattern = pattern_from_strlist (names);
  if (!pattern)
    return out_of_core ();
  snprintf (line, DIM(line)-1, "LOOKUP %s", pattern);
  line[DIM(line)-1] = 0;
  xfree (pattern);

  parm.ctrl = ctrl;
  parm.ctx = dirmngr_ctx;
  parm.cb = cb;
  parm.cb_value = cb_value;
  parm.error = 0;
  init_membuf (&parm.data, 4096);

  rc = assuan_transact (dirmngr_ctx, line, lookup_cb, &parm,
                        NULL, NULL, lookup_status_cb, &parm);
  xfree (get_membuf (&parm.data, &len));
  if (rc)
    return rc;
  return parm.error;
}



/* Run Command helpers*/

/* Fairly simple callback to write all output of dirmngr to stdout. */
static int
run_command_cb (void *opaque, const void *buffer, size_t length)
{
  if (buffer)
    {
      if ( fwrite (buffer, length, 1, stdout) != 1 )
        log_error ("error writing to stdout: %s\n", strerror (errno));
    }
  return 0;
}

/* Handle inquiries from the dirmngr COMMAND. */
static int
run_command_inq_cb (void *opaque, const char *line)
{
  struct run_command_parm_s *parm = opaque;
  int rc = 0;

  if ( !strncmp (line, "SENDCERT", 8) && (line[8] == ' ' || !line[8]) )
    { /* send the given certificate */
      int err;
      ksba_cert_t cert;
      const unsigned char *der;
      size_t derlen;

      line += 8;
      if (!*line)
        return gpg_error (GPG_ERR_ASS_PARAMETER);

      err = gpgsm_find_cert (line, NULL, &cert);
      if (err)
        {
          log_error ("certificate not found: %s\n", gpg_strerror (err));
          rc = gpg_error (GPG_ERR_NOT_FOUND);
        }
      else
        {
          der = ksba_cert_get_image (cert, &derlen);
          if (!der)
            rc = gpg_error (GPG_ERR_INV_CERT_OBJ);
          else
            rc = assuan_send_data (parm->ctx, der, derlen);
          ksba_cert_release (cert);
        }
    }
  else if ( !strncmp (line, "PRINTINFO", 9) && (line[9] == ' ' || !line[9]) )
    { /* Simply show the message given in the argument. */
      line += 9;
      log_info ("dirmngr: %s\n", line);
    }
  else
    {
      log_error ("unsupported inquiry `%s'\n", line);
      rc = gpg_error (GPG_ERR_ASS_UNKNOWN_INQUIRE);
    }

  return rc; 
}

static int
run_command_status_cb (void *opaque, const char *line)
{
  ctrl_t ctrl = opaque;

  if (opt.verbose)
    {
      log_info ("dirmngr status: %s\n", line);
    }
  if (!strncmp (line, "PROGRESS", 8) && (line[8]==' ' || !line[8]))
    {
      if (ctrl)
        {
          for (line += 8; *line == ' '; line++)
            ;
          if (gpgsm_status (ctrl, STATUS_PROGRESS, line))
            return gpg_error (GPG_ERR_ASS_CANCELED);
        }
    }
  return 0;
}



/* Pass COMMAND to dirmngr and print all output generated by Dirmngr
   to stdout.  A couple of inquiries are defined (see above).  ARGC
   arguments in ARGV are given to the Dirmngr.  Spaces, plus and
   percent characters within the argument strings are percent escaped
   so that blanks can act as delimiters. */
int
gpgsm_dirmngr_run_command (ctrl_t ctrl, const char *command,
                           int argc, char **argv)
{ 
  int rc;
  int i;
  const char *s;
  char *line, *p;
  size_t len;
  struct run_command_parm_s parm;

  rc = start_dirmngr ();
  if (rc)
    return rc;

  parm.ctx = dirmngr_ctx;

  len = strlen (command) + 1;
  for (i=0; i < argc; i++)
    len += 1 + 3*strlen (argv[i]); /* enough space for percent escaping */
  line = xtrymalloc (len);
  if (!line)
    return out_of_core ();

  p = stpcpy (line, command);
  for (i=0; i < argc; i++)
    {
      *p++ = ' ';
      for (s=argv[i]; *s; s++)
        {
          if (!isascii (*s))
            *p++ = *s;
          else if (*s == ' ')
            *p++ = '+';
          else if (!isprint (*s) || *s == '+')
            {
              sprintf (p, "%%%02X", *(const unsigned char *)s);
              p += 3;
            }
          else
            *p++ = *s;
        }
    }
  *p = 0;

  rc = assuan_transact (dirmngr_ctx, line,
                        run_command_cb, NULL,
                        run_command_inq_cb, &parm,
                        run_command_status_cb, ctrl);
  xfree (line);
  log_info ("response of dirmngr: %s\n", rc? gpg_strerror (rc): "okay");
  return rc;
}