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/* app-help.c - Application helper functions
* Copyright (C) 2004, 2009 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 <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "scdaemon.h"
#include "app-common.h"
#include "iso7816.h"
#include "tlv.h"
/* Count the number of bits, assuming the A represents an unsigned big
integer of length LEN bytes. If A is NULL a length of 0 is
returned. */
unsigned int
app_help_count_bits (const unsigned char *a, size_t len)
{
unsigned int n = len * 8;
int i;
if (!a)
return 0;
for (; len && !*a; len--, a++, n -=8)
;
if (len)
{
for (i=7; i && !(*a & (1<<i)); i--)
n--;
}
return n;
}
/* Return the KEYGRIP for the certificate CERT as an hex encoded
string in the user provided buffer HEXKEYGRIP which must be of at
least 41 bytes. */
gpg_error_t
app_help_get_keygrip_string (ksba_cert_t cert, char *hexkeygrip)
{
gpg_error_t err;
gcry_sexp_t s_pkey;
ksba_sexp_t p;
size_t n;
unsigned char array[20];
p = ksba_cert_get_public_key (cert);
if (!p)
return gpg_error (GPG_ERR_BUG);
n = gcry_sexp_canon_len (p, 0, NULL, NULL);
if (!n)
return gpg_error (GPG_ERR_INV_SEXP);
err = gcry_sexp_sscan (&s_pkey, NULL, (char*)p, n);
xfree (p);
if (err)
return err; /* Can't parse that S-expression. */
if (!gcry_pk_get_keygrip (s_pkey, array))
{
gcry_sexp_release (s_pkey);
return gpg_error (GPG_ERR_GENERAL); /* Failed to calculate the keygrip.*/
}
gcry_sexp_release (s_pkey);
bin2hex (array, 20, hexkeygrip);
return 0;
}
/* Given the SLOT and the File ID FID, return the length of the
certificate contained in that file. Returns 0 if the file does not
exists or does not contain a certificate. If R_CERTOFF is not
NULL, the length the header will be stored at this address; thus to
parse the X.509 certificate a read should start at that offset.
On success the file is still selected.
*/
size_t
app_help_read_length_of_cert (int slot, int fid, size_t *r_certoff)
{
gpg_error_t err;
unsigned char *buffer;
const unsigned char *p;
size_t buflen, n;
int class, tag, constructed, ndef;
size_t resultlen, objlen, hdrlen;
err = iso7816_select_file (slot, fid, 0, NULL, NULL);
if (err)
{
log_info ("error selecting FID 0x%04X: %s\n", fid, gpg_strerror (err));
return 0;
}
err = iso7816_read_binary (slot, 0, 32, &buffer, &buflen);
if (err)
{
log_info ("error reading certificate from FID 0x%04X: %s\n",
fid, gpg_strerror (err));
return 0;
}
if (!buflen || *buffer == 0xff)
{
log_info ("no certificate contained in FID 0x%04X\n", fid);
xfree (buffer);
return 0;
}
p = buffer;
n = buflen;
err = parse_ber_header (&p, &n, &class, &tag, &constructed,
&ndef, &objlen, &hdrlen);
if (err)
{
log_info ("error parsing certificate in FID 0x%04X: %s\n",
fid, gpg_strerror (err));
xfree (buffer);
return 0;
}
/* All certificates should commence with a SEQUENCE except for the
special ROOT CA which are enclosed in a SET. */
if ( !(class == CLASS_UNIVERSAL && constructed
&& (tag == TAG_SEQUENCE || tag == TAG_SET)))
{
log_info ("data at FID 0x%04X does not look like a certificate\n", fid);
return 0;
}
resultlen = objlen + hdrlen;
if (r_certoff)
{
/* The callers want the offset to the actual certificate. */
*r_certoff = hdrlen;
err = parse_ber_header (&p, &n, &class, &tag, &constructed,
&ndef, &objlen, &hdrlen);
if (err)
return 0;
if (class == CLASS_UNIVERSAL && tag == TAG_OBJECT_ID && !constructed)
{
/* The certificate seems to be contained in a
userCertificate container. Assume the following sequence
is the certificate. */
*r_certoff += hdrlen + objlen;
if (*r_certoff > resultlen)
{
*r_certoff = 0;
return 0; /* That should never happen. */
}
}
else
*r_certoff = 0;
}
return resultlen;
}

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Mon, Dec 23, 4:22 PM (15 h, 1 m)
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