libsxmp/sxt/safebuffer.c

/*
 * Secure eXtended Message Passing framework
 * Secure eXtended Transport layer implementation: (libsxt)
 * - very similar to SSH2/TLS
 * - using already proven and tested crypto algos
 * - better than TLS for message passing
 *
 * (c) Alexander Vdolainen 2016 <avdolainen@zoho.com>
 *
 * libsxmp 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 2.1 of the License, or
 * (at your option) any later version.
 *
 * libsxmp 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 program.  If not, see <http://www.gnu.org/licenses/>.";
 *
 */

#include <stdint.h>
#include <stdlib.h>
#include <limits.h>
#include <sys/types.h>
#include <arpa/inet.h>
#include <string.h>

#include <sxt/safebuf.h>

sxtsafebuffer_t *sxtsafebuffer_new(size_t size)
{
  sxtsafebuffer_t *buf = NULL;

  if(size > (UINT_MAX - sizeof(sxtsafebuffer_t))) return NULL;

  if(!(buf = malloc(sizeof(sxtsafebuffer_t) + size))) return NULL;

  buf->size = htonl(size);
  buf->data[0] = 0;

  return buf;
}

int sxtsafebuffer_setdata(sxtsafebuffer_t *buf, const void *data, size_t size)
{
  /* validate parameters */
  if(!buf || !data) return -1;
  if(!size || size > sxtsafebuffer_length(buf)) return -1;

  memcpy(buf->data, data, size);

  return 0;
}

size_t sxtsafebuffer_length(sxtsafebuffer_t *buf)
{
  size_t size = 0;

  if(!buf) return size;
  else size = ntohl(buf->size);

  if((size > 0) && (size < UINT_MAX)) return size;

  return 0;
}

void sxtsafebuffer_destroy(sxtsafebuffer_t *buf)
{
  if(!buf) return;

  buf->size = 0;
  memset((void *)buf->data, 0, sxtsafebuffer_length(buf));
  free(buf);

  return;
}

void *sxtsafebuffer_getdata(sxtsafebuffer_t *buf)
{
  if(!buf) return NULL;

  return (void *)buf->data;
}

/* C string ops */
const char *sxtsafebuffer_tocstr(sxtsafebuffer_t *buf)
{
  if(!buf) return NULL;

  buf->data[sxtsafebuffer_length(buf)] = '\0';

  return (const char *)buf->data;;
}

sxtsafebuffer_t *sxtsafebuffer_new_fromcstr(const char *str)
{
  size_t length;
  sxtsafebuffer_t *buf = NULL;

  if(!str) return NULL;
  else length = strlen(str);

  if(!(buf = sxtsafebuffer_new(length))) return NULL;
  else memcpy(buf->data, str, length);

  return buf;
}

/* returning value should be freed after use */
char *sxtsafebuffer_getcstr(sxtsafebuffer_t *buf)
{
  size_t length;
  char *str = NULL;

  if(!buf) return NULL;

  length = sxtsafebuffer_length(buf);
  if(length <= 0) return NULL;

  if(!(str = malloc(length + 1))) return NULL;
  else memcpy(str, buf->data, length);

  str[length] = '\0';

  return str;
}

void sxtsafebuffer_freecstr(char *str)
{
  if(!str) return;

  memset(str, 0, strlen(str));
  free(str);

  return;
}