inetutils/libinetutils/des_rw.c

/*
  Copyright (C) 1997-2025 Free Software Foundation, Inc.

  This file is part of GNU Inetutils.

  GNU Inetutils 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.

  GNU Inetutils 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/'. */

/*
 * Copyright (c) 1989, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <config.h>

#ifdef ENCRYPTION
# ifdef KRB4
#  include <sys/param.h>

#  ifdef HAVE_KERBEROSIV_DES_H
#   include <kerberosIV/des.h>
#  endif
#  ifdef HAVE_KERBEROSIV_KRB_H
#   include <kerberosIV/krb.h>
#  endif

#  include <stdlib.h>
#  include <string.h>
#  include <time.h>
#  include <unistd.h>

#  ifndef MIN
#   define MIN(a,b)	(((a)<(b))? (a):(b))
#  endif
#  ifndef roundup
#   define roundup(x, y)   ((((x)+((y)-1))/(y))*(y))
#  endif

static unsigned char des_inbuf[10240], storage[10240], *store_ptr;
static bit_64 *key;
static unsigned char *key_schedule;

/* XXX these should be in a kerberos include file */
int krb_net_read (int, char *, int);

/*
 * NB: These routines will not function properly if NBIO
 *	is set
 */

void
des_clear_key (void)
{
  memset (key, 0, sizeof (C_Block));
  memset (key_schedule, 0, sizeof (Key_schedule));
}


int
des_read (int fd, char *buf, int len)
{
  int nreturned = 0;
  long net_len, rd_len;
  int nstored = 0;

  if (nstored >= len)
    {
      memcpy (buf, store_ptr, len);
      store_ptr += len;
      nstored -= len;
      return (len);
    }
  else if (nstored)
    {
      memcpy (buf, store_ptr, nstored);
      nreturned += nstored;
      buf += nstored;
      len -= nstored;
      nstored = 0;
    }

  if (krb_net_read (fd, (char *) &net_len, sizeof (net_len)) !=
      sizeof (net_len))
    {
      /* XXX can't read enough, pipe
         must have closed */
      return (0);
    }
  net_len = ntohl (net_len);
  if (net_len <= 0 || net_len > sizeof (des_inbuf))
    {
      /* preposterous length; assume out-of-sync; only
         recourse is to close connection, so return 0 */
      return (0);
    }
  /* the writer tells us how much real data we are getting, but
     we need to read the pad bytes (8-byte boundary) */
  rd_len = roundup (net_len, 8);
  if (krb_net_read (fd, (char *) des_inbuf, rd_len) != rd_len)
    {
      /* pipe must have closed, return 0 */
      return (0);
    }
  des_pcbc_encrypt (des_inbuf,	/* inbuf */
		    storage,	/* outbuf */
		    net_len,	/* length */
		    key_schedule,	/* DES key */
		    key,	/* IV */
		    DECRYPT);	/* direction */

  if (net_len < 8)
    store_ptr = storage + 8 - net_len;
  else
    store_ptr = storage;

  nstored = net_len;
  if (nstored > len)
    {
      memcpy (buf, store_ptr, len);
      nreturned += len;
      store_ptr += len;
      nstored -= len;
    }
  else
    {
      memcpy (buf, store_ptr, nstored);
      nreturned += nstored;
      nstored = 0;
    }

  return (nreturned);
}

static unsigned char des_outbuf[10240];	/* > longest write */

int
des_write (int fd, char *buf, int len)
{
  static int seeded = 0;
  static char garbage_buf[8];
  long net_len, garbage;

  if (len < 8)
    {
      if (!seeded)
	{
	  seeded = 1;
	  srandom ((int) time ((long *) 0));
	}
      garbage = random ();
      /* insert random garbage */
      memcpy (garbage_buf, &garbage, MIN (sizeof (long), 8));
      /* this "right-justifies" the data in the buffer */
      memcpy (garbage_buf + 8 - len, buf, len);
    }
  /* pcbc_encrypt outputs in 8-byte (64 bit) increments */

  des_pcbc_encrypt ((len < 8) ? garbage_buf : buf, des_outbuf, (len < 8) ? 8 : len, key_schedule,	/* DES key */
		    key,	/* IV */
		    ENCRYPT);

  /* tell the other end the real amount, but send an 8-byte padded
     packet */
  net_len = htonl (len);
  write (fd, &net_len, sizeof (net_len));
  write (fd, des_outbuf, roundup (len, 8));
  return (len);
}
# endif/* KRB4 */
#endif /* CRYPT */