265 lines
7.8 KiB
C
265 lines
7.8 KiB
C
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/*
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* Copyright (c) 1996
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* Bill Paul <wpaul@ctr.columbia.edu>. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by Bill Paul.
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* 4. Neither the name of the author nor the names of any co-contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY Bill Paul AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL Bill Paul OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $Id: crypt_server.c,v 1.15 1996/12/25 19:21:10 wpaul Exp $
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*/
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#include <stdio.h>
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#include <sys/types.h>
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#include <sys/param.h>
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#include <stdlib.h>
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#include <dirent.h>
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#include <err.h>
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#include <rpc/des_crypt.h>
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#include <rpc/des.h>
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#include <string.h>
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#include <dlfcn.h>
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#include "crypt.h"
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#ifndef lint
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static const char rcsid[] = "$Id: crypt_server.c,v 1.15 1996/12/25 19:21:10 wpaul Exp $";
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#endif
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/*
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* The U.S. government stupidly believes that a) it can keep strong
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* crypto code a secret and b) that doing so somehow protects national
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* interests. It's wrong on both counts, but until it listens to reason
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* we have to make certain compromises so it doesn't have an excuse to
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* throw us in federal prison.
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*
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* Consequently, the core OS ships without DES support, and keyserv
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* defaults to using RC4 with only a 40 bit key, just like nutscrape.
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* This breaks compatibility with Secure RPC on other systems, but it
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* allows Secure RPC to work between FreeBSD systems that don't have the
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* DES package installed without throwing security totally out the window.
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*
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* In order to avoid having to supply two versions of keyserv (one with
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* DES and one without), we use dlopen() and friends to load libdes.so
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* into our address space at runtime. We check for the presence of
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* /usr/lib/libdes.so.3.0 at startup and load it if we find it. If we
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* can't find it, or the __des_crypt symbol doesn't exist, we fall back
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* to the RC4 encryption code. The user can specify another path using
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* the -p flag.
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*/
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/* rc4.h */
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typedef struct rc4_key
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{
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unsigned char state[256];
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unsigned char x;
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unsigned char y;
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} rc4_key;
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static void prepare_key(unsigned char *key_data_ptr,int key_data_len,
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rc4_key *key);
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static void rc4(unsigned char *buffer_ptr,int buffer_len,rc4_key * key);
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static void swap_byte(unsigned char *a, unsigned char *b);
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static void prepare_key(unsigned char *key_data_ptr, int key_data_len,
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rc4_key *key)
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{
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unsigned char index1;
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unsigned char index2;
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unsigned char* state;
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short counter;
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state = &key->state[0];
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for(counter = 0; counter < 256; counter++)
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state[counter] = counter;
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key->x = 0;
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key->y = 0;
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index1 = 0;
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index2 = 0;
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for(counter = 0; counter < 256; counter++)
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{
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index2 = (key_data_ptr[index1] + state[counter] +
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index2) % 256;
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swap_byte(&state[counter], &state[index2]);
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index1 = (index1 + 1) % key_data_len;
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}
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}
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static void rc4(unsigned char *buffer_ptr, int buffer_len, rc4_key *key)
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{
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unsigned char x;
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unsigned char y;
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unsigned char* state;
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unsigned char xorIndex;
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short counter;
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x = key->x;
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y = key->y;
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state = &key->state[0];
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for(counter = 0; counter < buffer_len; counter ++)
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{
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x = (x + 1) % 256;
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y = (state[x] + y) % 256;
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swap_byte(&state[x], &state[y]);
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xorIndex = (state[x] + state[y]) % 256;
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buffer_ptr[counter] ^= state[xorIndex];
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}
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key->x = x;
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key->y = y;
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}
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static void swap_byte(unsigned char *a, unsigned char *b)
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{
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unsigned char swapByte;
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swapByte = *a;
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*a = *b;
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*b = swapByte;
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}
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/* Dummy _des_crypt function that uses RC4 with a 40 bit key */
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int _rc4_crypt(buf, len, desp)
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char *buf;
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int len;
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struct desparams *desp;
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{
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struct rc4_key rc4k;
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/*
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* U.S. government anti-crypto weasels take
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* note: although we are supplied with a 64 bit
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* key, we're only passing 40 bits to the RC4
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* encryption code. So there.
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*/
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prepare_key(desp->des_key, 5, &rc4k);
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rc4(buf, len, &rc4k);
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return(DESERR_NOHWDEVICE);
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}
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int (*_my_crypt)__P((char *, int, struct desparams *)) = NULL;
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static void *dlhandle;
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#ifndef _PATH_USRLIB
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#define _PATH_USRLIB "/usr/lib"
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#endif
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#ifndef LIBDES
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#define LIBDES "libdes.so.3."
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#endif
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void load_des(warn, libpath)
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int warn;
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char *libpath;
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{
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DIR *dird;
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struct dirent *dirp;
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char dlpath[MAXPATHLEN];
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int minor = -1;
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int len;
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if (libpath == NULL) {
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len = strlen(LIBDES);
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if ((dird = opendir(_PATH_USRLIB)) == NULL)
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err(1, "opendir(/usr/lib) failed");
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while ((dirp = readdir(dird)) != NULL) {
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/* must have a minor number */
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if (strlen(dirp->d_name) <= len)
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continue;
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if (!strncmp(dirp->d_name, LIBDES, len)) {
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if (atoi((dirp->d_name + len + 1)) > minor) {
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minor = atoi((dirp->d_name + len + 1));
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snprintf(dlpath,sizeof(dlpath),"%s/%s",
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_PATH_USRLIB, dirp->d_name);
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}
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}
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}
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closedir(dird);
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} else
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snprintf(dlpath, sizeof(dlpath), "%s", libpath);
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if (dlpath != NULL && (dlhandle = dlopen(dlpath, 0444)) != NULL)
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_my_crypt = (int (*)())dlsym(dlhandle, "__des_crypt");
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if (_my_crypt == NULL) {
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if (dlhandle != NULL)
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dlclose(dlhandle);
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_my_crypt = &_rc4_crypt;
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if (warn) {
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printf ("DES support disabled -- using RC4 instead.\n");
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printf ("Warning: RC4 cipher is not compatible with ");
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printf ("other Secure RPC implementations.\nInstall ");
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printf ("the FreeBSD 'des' distribution to enable");
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printf (" DES encryption.\n");
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}
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} else {
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if (warn) {
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printf ("DES support enabled\n");
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printf ("Using %s shared object.\n", dlpath);
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}
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}
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return;
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}
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desresp *
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des_crypt_1_svc(desargs *argp, struct svc_req *rqstp)
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{
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static desresp result;
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struct desparams dparm;
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if (argp->desbuf.desbuf_len > DES_MAXDATA) {
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result.stat = DESERR_BADPARAM;
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return(&result);
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}
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bcopy(argp->des_key, dparm.des_key, 8);
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bcopy(argp->des_ivec, dparm.des_ivec, 8);
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dparm.des_mode = argp->des_mode;
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dparm.des_dir = argp->des_dir;
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#ifdef BROKEN_DES
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dparm.UDES.UDES_buf = argp->desbuf.desbuf_val;
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#endif
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result.stat = _my_crypt(argp->desbuf.desbuf_val,
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argp->desbuf.desbuf_len,
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&dparm);
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if (result.stat == DESERR_NONE || result.stat == DESERR_NOHWDEVICE) {
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bcopy(dparm.des_ivec, result.des_ivec, 8);
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result.desbuf.desbuf_len = argp->desbuf.desbuf_len;
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result.desbuf.desbuf_val = argp->desbuf.desbuf_val;
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}
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return (&result);
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}
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