secret.c
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/* GNU Mailutils -- a suite of utilities for electronic mail
Copyright (C) 2009-2012, 2014-2016 Free Software Foundation, Inc.
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 3 of the License, or (at your option) any later version.
This library 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General
Public License along with this library. If not, see
<http://www.gnu.org/licenses/>. */
#ifdef HAVE_CONFIG_H
# include <config.h>
#endif
#include <stdlib.h>
#include <string.h>
#include <mailutils/types.h>
#include <mailutils/secret.h>
#include <mailutils/errno.h>
struct _mu_secret
{
unsigned int refcnt; /* Number of references to this object */
size_t length; /* Secret length */
unsigned char *obptr; /* Obfuscated data */
unsigned char *clptr; /* Cleartext data */
unsigned int clref; /* Number of references to clptr returned
this far */
};
static unsigned char xchar;
static void
obfuscate (const unsigned char *input, unsigned char *output, size_t len)
{
if (!xchar)
xchar = random () % 255;
while (len--)
*output++ = *input++ ^ xchar;
}
int
mu_secret_create (mu_secret_t *psec, const char *value, size_t len)
{
mu_secret_t sec;
sec = calloc (1, sizeof (sec[0]) + 2 * (len + 1));
if (!sec)
return ENOMEM;
sec->obptr = (unsigned char*)(sec + 1);
sec->clptr = sec->obptr + len + 1;
obfuscate ((unsigned char *) value, sec->obptr, len);
sec->length = len;
*psec = sec;
mu_secret_ref (sec);
return 0;
}
int
mu_secret_dup (mu_secret_t sec, mu_secret_t *newsec)
{
const char *pass = mu_secret_password (sec);
int rc = mu_secret_create (newsec, pass, strlen (pass));
mu_secret_password_unref (sec);
return rc;
}
void
mu_secret_ref (mu_secret_t sec)
{
if (sec)
sec->refcnt++;
}
/* Decrement reference counter in SEC. If it falls to 0, free memory
allocated for SEC and return 0. Otherwise, return MU_ERR_EXISTS,
indicating that someone else is still holding it.
Return EINVAL if sec==NULL. */
int
mu_secret_unref (mu_secret_t sec)
{
if (sec)
{
if (sec->refcnt)
sec->refcnt--;
if (sec->refcnt == 0)
{
memset (sec->clptr, 0, sec->length);
memset (sec->obptr, 0, sec->length);
free (sec);
return 0;
}
return MU_ERR_EXISTS;
}
return EINVAL;
}
void
mu_secret_destroy (mu_secret_t *psec)
{
if (psec && *psec && mu_secret_unref (*psec) == 0)
*psec = NULL;
}
const char *
mu_secret_password (mu_secret_t sec)
{
if (!sec)
return 0;
if (sec->clref++ == 0)
obfuscate (sec->obptr, sec->clptr, sec->length);
return (const char*) sec->clptr;
}
size_t
mu_secret_length (mu_secret_t sec)
{
if (!sec)
return 0;
return sec->length;
}
void
mu_secret_password_unref (mu_secret_t sec)
{
if (--sec->clref == 0)
memset (sec->clptr, 0, sec->length);
}