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/* convert.c - Hex conversion functions.
* Copyright (C) 2006 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 2 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, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
* USA.
*/
#include <config.h>
#include <stdlib.h>
#include <errno.h>
#include <ctype.h>
#include "util.h"
#define tohex(n) ((n) < 10 ? ((n) + '0') : (((n) - 10) + 'A'))
/* Convert STRING consisting of hex characters into its binary representation
and store that at BUFFER. BUFFER needs to be of LENGTH bytes. The
function check that the STRING will convert exactly to LENGTH
bytes. Colons inbetween the hex digits are allowed, if one colon
has been given a colon is expected very 2 characters. The string
is delimited by either end of string or a white space character.
The function returns -1 on error or the length of the parsed
string. */
int
hexcolon2bin (const char *string, void *buffer, size_t length)
{
int i;
const char *s = string;
int need_colon = 0;
for (i=0; i < length; )
{
if (i==1 && *s == ':') /* Skip colons between hex digits. */
{
need_colon = 1;
s++;
}
else if (need_colon && *s == ':')
s++;
else if (need_colon)
return -1; /* Colon expected. */
if (!hexdigitp (s) || !hexdigitp (s+1))
return -1; /* Invalid hex digits. */
((unsigned char*)buffer)[i++] = xtoi_2 (s);
s += 2;
}
if (*s == ':')
return -1; /* Trailing colons are not allowed. */
if (*s && (!isascii (*s) || !isspace (*s)) )
return -1; /* Not followed by Nul or white space. */
if (i != length)
return -1; /* Not of expected length. */
if (*s)
s++; /* Skip the delimiter. */
return s - string;
}
static char *
do_bin2hex (const void *buffer, size_t length, char *stringbuf, int with_colon)
{
const unsigned char *s;
char *p;
if (!stringbuf)
{
/* Not really correct for with_colon but we don't care about the
one wasted byte. */
size_t n = with_colon? 3:2;
size_t nbytes = n * length + 1;
if (length && (nbytes-1) / n != length)
{
errno = ENOMEM;
return NULL;
}
stringbuf = xtrymalloc (nbytes);
if (!stringbuf)
return NULL;
}
for (s = buffer, p = stringbuf; length; length--, s++)
{
if (with_colon && s != buffer)
*p++ = ':';
*p++ = tohex ((*s>>4)&15);
*p++ = tohex (*s&15);
}
*p = 0;
return stringbuf;
}
/* Convert LENGTH bytes of data in BUFFER into hex encoding and store
that at the provided STRINGBUF. STRINGBUF must be allocated of at
least (2*LENGTH+1) bytes or be NULL so that the function mallocs an
appropriate buffer. Returns STRINGBUF or NULL on error (which may
only occur if STRINGBUF has been NULL and the internal malloc
failed). */
char *
bin2hex (const void *buffer, size_t length, char *stringbuf)
{
return do_bin2hex (buffer, length, stringbuf, 0);
}
/* Convert LENGTH bytes of data in BUFFER into hex encoding and store
that at the provided STRINGBUF. STRINGBUF must be allocated of at
least (3*LENGTH+1) bytes or be NULL so that the function mallocs an
appropriate buffer. Returns STRINGBUF or NULL on error (which may
only occur if STRINGBUF has been NULL and the internal malloc
failed). */
char *
bin2hexcolon (const void *buffer, size_t length, char *stringbuf)
{
return do_bin2hex (buffer, length, stringbuf, 1);
}
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