/*      $NetBSD: encrypt.c,v 1.20 2024/10/29 13:10:06 kre Exp $ */

/*-
* Copyright (c) 1991, 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 <sys/cdefs.h>
#if 0
static char sccsid[] = "@(#)encrypt.c   8.2 (Berkeley) 5/30/95";
#else
__RCSID("$NetBSD: encrypt.c,v 1.20 2024/10/29 13:10:06 kre Exp $");
#endif /* not lint */

/*
* Copyright (C) 1990 by the Massachusetts Institute of Technology
*
* Export of this software from the United States of America is assumed
* to require a specific license from the United States Government.
* It is the responsibility of any person or organization contemplating
* export to obtain such a license before exporting.
*
* WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
* distribute this software and its documentation for any purpose and
* without fee is hereby granted, provided that the above copyright
* notice appear in all copies and that both that copyright notice and
* this permission notice appear in supporting documentation, and that
* the name of M.I.T. not be used in advertising or publicity pertaining
* to distribution of the software without specific, written prior
* permission.  M.I.T. makes no representations about the suitability of
* this software for any purpose.  It is provided "as is" without express
* or implied warranty.
*/

#ifdef  ENCRYPTION

#include <stdio.h>
#define ENCRYPT_NAMES
#include <arpa/telnet.h>

#include "encrypt.h"
#include "misc.h"

#include <stdlib.h>
#ifdef  NO_STRING_H
#include <strings.h>
#else
#include <string.h>
#endif

/*
* These functions pointers point to the current routines
* for encrypting and decrypting data.
*/
void    (*encrypt_output)(unsigned char *, int);
int     (*decrypt_input)(int);

static int encrypt_debug_mode = 0;
static int decrypt_mode = 0;
static int encrypt_mode = 0;
static int encrypt_verbose = 0;
static int autoencrypt = 0;
static int autodecrypt = 0;
static int havesessionkey = 0;
static int Server = 0;
static const char *Name = "Noname";

#define typemask(x)     ((x) > 0 ? 1 << ((x)-1) : 0)

static long i_support_encrypt = typemask(ENCTYPE_DES_CFB64)
                               | typemask(ENCTYPE_DES_OFB64);
static long i_support_decrypt = typemask(ENCTYPE_DES_CFB64)
                               | typemask(ENCTYPE_DES_OFB64);
static long i_wont_support_encrypt = 0;
static long i_wont_support_decrypt = 0;
#define I_SUPPORT_ENCRYPT       (i_support_encrypt & ~i_wont_support_encrypt)
#define I_SUPPORT_DECRYPT       (i_support_decrypt & ~i_wont_support_decrypt)

static long remote_supports_encrypt = 0;
static long remote_supports_decrypt = 0;

static Encryptions encryptions[] = {
#ifdef  DES_ENCRYPTION
   { "DES_CFB64",      ENCTYPE_DES_CFB64,
                       cfb64_encrypt,
                       cfb64_decrypt,
                       cfb64_init,
                       cfb64_start,
                       cfb64_is,
                       cfb64_reply,
                       cfb64_session,
                       cfb64_keyid,
                       cfb64_printsub },
   { "DES_OFB64",      ENCTYPE_DES_OFB64,
                       ofb64_encrypt,
                       ofb64_decrypt,
                       ofb64_init,
                       ofb64_start,
                       ofb64_is,
                       ofb64_reply,
                       ofb64_session,
                       ofb64_keyid,
                       ofb64_printsub },
#endif  /* DES_ENCRYPTION */
   { .name = 0 },
};

static unsigned char str_send[64] = { IAC, SB, TELOPT_ENCRYPT,
                                        ENCRYPT_SUPPORT };
static unsigned char str_suplen = 0;
static unsigned char str_start[72] = { IAC, SB, TELOPT_ENCRYPT };
static unsigned char str_end[] = { IAC, SB, TELOPT_ENCRYPT, 0, IAC, SE };

Encryptions *
findencryption(int type)
{
       Encryptions *ep = encryptions;

       if (!(I_SUPPORT_ENCRYPT & remote_supports_decrypt & typemask(type)))
               return(0);
       while (ep->type && ep->type != type)
               ++ep;
       return(ep->type ? ep : 0);
}

Encryptions *
finddecryption(int type)
{
       Encryptions *ep = encryptions;

       if (!(I_SUPPORT_DECRYPT & remote_supports_encrypt & typemask(type)))
               return(0);
       while (ep->type && ep->type != type)
               ++ep;
       return(ep->type ? ep : 0);
}

#define MAXKEYLEN 64

static struct key_info {
       unsigned char keyid[MAXKEYLEN];
       int keylen;
       int dir;
       int *modep;
       Encryptions *(*getcrypt)(int);
} ki[2] = {
       { { 0 }, 0, DIR_ENCRYPT, &encrypt_mode, findencryption },
       { { 0 }, 0, DIR_DECRYPT, &decrypt_mode, finddecryption },
};

void
encrypt_init(const char *name, int server)
{
       Encryptions *ep = encryptions;

       Name = name;
       Server = server;
       i_support_encrypt = i_support_decrypt = 0;
       remote_supports_encrypt = remote_supports_decrypt = 0;
       encrypt_mode = 0;
       decrypt_mode = 0;
       encrypt_output = 0;
       decrypt_input = 0;
#ifdef notdef
       encrypt_verbose = !server;
#endif

       str_suplen = 4;

       while (ep->type) {
               if (encrypt_debug())
                       printf(">>>%s: I will support %s\r\n",
                               Name, ENCTYPE_NAME(ep->type));
               i_support_encrypt |= typemask(ep->type);
               i_support_decrypt |= typemask(ep->type);
               if ((i_wont_support_decrypt & typemask(ep->type)) == 0)
                       if ((str_send[str_suplen++] = ep->type) == IAC)
                               str_send[str_suplen++] = IAC;
               if (ep->init)
                       (*ep->init)(Server);
               ++ep;
       }
       str_send[str_suplen++] = IAC;
       str_send[str_suplen++] = SE;
}

void
encrypt_list_types(void)
{
       Encryptions *ep = encryptions;

       printf("Valid encryption types:\n");
       while (ep->type) {
               printf("\t%s (%d)\r\n", ENCTYPE_NAME(ep->type), ep->type);
               ++ep;
       }
}

int
EncryptEnable(char *type, char *mode)
{
       if (isprefix(type, "help") || isprefix(type, "?")) {
               printf("Usage: encrypt enable <type> [input|output]\n");
               encrypt_list_types();
               return 0;
       }
       if (EncryptType(type, mode))
               return EncryptStart(mode, NULL);
       return 0;
}

int
EncryptDisable(char *type, char *mode)
{
       register Encryptions *ep;
       int ret = 0;

       if (isprefix(type, "help") || isprefix(type, "?")) {
               printf("Usage: encrypt disable <type> [input|output]\n");
               encrypt_list_types();
       } else if ((ep = (Encryptions *)genget(type, (char **)encryptions,
                                               sizeof(Encryptions))) == 0) {
               printf("%s: invalid encryption type\n", type);
       } else if (Ambiguous(ep)) {
               printf("Ambiguous type '%s'\n", type);
       } else {
               if ((mode == 0) || (isprefix(mode, "input") ? 1 : 0)) {
                       if (decrypt_mode == ep->type)
                               EncryptStopInput(NULL, NULL);
                       i_wont_support_decrypt |= typemask(ep->type);
                       ret = 1;
               }
               if ((mode == 0) || (isprefix(mode, "output"))) {
                       if (encrypt_mode == ep->type)
                               EncryptStopOutput(NULL, NULL);
                       i_wont_support_encrypt |= typemask(ep->type);
                       ret = 1;
               }
               if (ret == 0)
                       printf("%s: invalid encryption mode\n", mode);
       }
       return(ret);
}

int
EncryptType(char *type, char *mode)
{
       register Encryptions *ep;
       int ret = 0;

       if (isprefix(type, "help") || isprefix(type, "?")) {
               printf("Usage: encrypt type <type> [input|output]\n");
               encrypt_list_types();
       } else if ((ep = (Encryptions *)genget(type, (char **)encryptions,
                                               sizeof(Encryptions))) == 0) {
               printf("%s: invalid encryption type\n", type);
       } else if (Ambiguous(ep)) {
               printf("Ambiguous type '%s'\n", type);
       } else {
               if ((mode == 0) || isprefix(mode, "input")) {
                       decrypt_mode = ep->type;
                       i_wont_support_decrypt &= ~typemask(ep->type);
                       ret = 1;
               }
               if ((mode == 0) || isprefix(mode, "output")) {
                       encrypt_mode = ep->type;
                       i_wont_support_encrypt &= ~typemask(ep->type);
                       ret = 1;
               }
               if (ret == 0)
                       printf("%s: invalid encryption mode\n", mode);
       }
       return(ret);
}

int
EncryptStart(char *mode, char *unused __unused)
{
       register int ret = 0;
       if (mode) {
               if (isprefix(mode, "input"))
                       return EncryptStartInput(NULL, NULL);
               if (isprefix(mode, "output"))
                       return EncryptStartOutput(NULL, NULL);
               if (isprefix(mode, "help") || isprefix(mode, "?")) {
                       printf("Usage: encrypt start [input|output]\n");
                       return 0;
               }
               printf("%s: invalid encryption mode 'encrypt start ?' for help\n", mode);
               return 0;
       }
       ret += EncryptStartInput(NULL, NULL);
       ret += EncryptStartOutput(NULL, NULL);
       return ret;
}

int
EncryptStartInput(char *unused1 __unused, char *unused2 __unused)
{
       if (decrypt_mode) {
               encrypt_send_request_start();
               return(1);
       }
       printf("No previous decryption mode, decryption not enabled\r\n");
       return(0);
}

int
EncryptStartOutput(char *unused1 __unused, char *unused2 __unused)
{
       if (encrypt_mode) {
               encrypt_start_output(encrypt_mode);
               return(1);
       }
       printf("No previous encryption mode, encryption not enabled\r\n");
       return(0);
}

int
EncryptStop(char *mode, char *unused __unused)
{
       int ret = 0;
       if (mode) {
               if (isprefix(mode, "input"))
                       return EncryptStopInput(NULL, NULL);
               if (isprefix(mode, "output"))
                       return EncryptStopOutput(NULL, NULL);
               if (isprefix(mode, "help") || isprefix(mode, "?")) {
                       printf("Usage: encrypt stop [input|output]\n");
                       return 0;
               }
               printf("%s: invalid encryption mode 'encrypt stop ?' for help\n", mode);
               return 0;
       }
       ret += EncryptStopInput(NULL, NULL);
       ret += EncryptStopOutput(NULL, NULL);
       return ret;
}

int
EncryptStopInput(char *unused1 __unused, char *unused2 __unused)
{
       encrypt_send_request_end();
       return 1;
}

int
EncryptStopOutput(char *unused1 __unused, char *unused2 __unused)
{
       encrypt_send_end();
       return 1;
}

void
encrypt_display(void)
{
       if (encrypt_output)
               printf("Currently encrypting output with %s\r\n",
                       ENCTYPE_NAME(encrypt_mode));
       if (decrypt_input)
               printf("Currently decrypting input with %s\r\n",
                       ENCTYPE_NAME(decrypt_mode));
}

int
EncryptStatus(char *unused1 __unused, char *unused2 __unused)
{
       if (encrypt_output)
               printf("Currently encrypting output with %s\r\n",
                       ENCTYPE_NAME(encrypt_mode));
       else if (encrypt_mode) {
               printf("Currently output is clear text.\r\n");
               printf("Last encryption mode was %s\r\n",
                       ENCTYPE_NAME(encrypt_mode));
       }
       if (decrypt_input) {
               printf("Currently decrypting input with %s\r\n",
                       ENCTYPE_NAME(decrypt_mode));
       } else if (decrypt_mode) {
               printf("Currently input is clear text.\r\n");
               printf("Last decryption mode was %s\r\n",
                       ENCTYPE_NAME(decrypt_mode));
       }
       return 1;
}

void
encrypt_send_support(void)
{
       if (str_suplen) {
               /*
                * If the user has requested that decryption start
                * immediately, then send a "REQUEST START" before
                * we negotiate the type.
                */
               if (!Server && autodecrypt)
                       encrypt_send_request_start();
               telnet_net_write(str_send, str_suplen);
               printsub('>', &str_send[2], str_suplen - 2);
               str_suplen = 0;
       }
}

int
EncryptDebug(int on)
{
       if (on < 0)
               encrypt_debug_mode ^= 1;
       else
               encrypt_debug_mode = on;
       printf("Encryption debugging %s\r\n",
               encrypt_debug_mode ? "enabled" : "disabled");
       return(1);
}

int
EncryptVerbose(int on)
{
       if (on < 0)
               encrypt_verbose ^= 1;
       else
               encrypt_verbose = on;
       printf("Encryption %s verbose\r\n",
               encrypt_verbose ? "is" : "is not");
       return(1);
}

int
EncryptAutoEnc(int on)
{
       encrypt_auto(on);
       printf("Automatic encryption of output is %s\r\n",
               autoencrypt ? "enabled" : "disabled");
       return(1);
}

int
EncryptAutoDec(int on)
{
       decrypt_auto(on);
       printf("Automatic decryption of input is %s\r\n",
               autodecrypt ? "enabled" : "disabled");
       return(1);
}

/*
* Called when ENCRYPT SUPPORT is received.
*/
void
encrypt_support(unsigned char *typelist, int cnt)
{
       register int type, use_type = 0;
       Encryptions *ep;

       /*
        * Forget anything the other side has previously told us.
        */
       remote_supports_decrypt = 0;

       while (cnt-- > 0) {
               type = *typelist++;
               if (encrypt_debug())
                       printf(">>>%s: He is supporting %s (%d)\r\n",
                               Name,
                               ENCTYPE_NAME(type), type);
               if ((type < ENCTYPE_CNT) &&
                   (I_SUPPORT_ENCRYPT & typemask(type))) {
                       remote_supports_decrypt |= typemask(type);
                       if (use_type == 0)
                               use_type = type;
               }
       }
       if (use_type) {
               ep = findencryption(use_type);
               if (!ep)
                       return;
               type = ep->start ? (*ep->start)(DIR_ENCRYPT, Server) : 0;
               if (encrypt_debug())
                       printf(">>>%s: (*ep->start)() returned %d\r\n",
                                       Name, type);
               if (type < 0)
                       return;
               encrypt_mode = use_type;
               if (type == 0)
                       encrypt_start_output(use_type);
       }
}

void
encrypt_is(unsigned char *data, int cnt)
{
       Encryptions *ep;
       register int type, ret;

       if (--cnt < 0)
               return;
       type = *data++;
       if (type < ENCTYPE_CNT)
               remote_supports_encrypt |= typemask(type);
       if (!(ep = finddecryption(type))) {
               if (encrypt_debug())
                       printf(">>>%s: Can't find type %s (%d) for initial negotiation\r\n",
                               Name,
                               ENCTYPE_NAME_OK(type)
                                       ? ENCTYPE_NAME(type) : "(unknown)",
                               type);
               return;
       }
       if (!ep->is) {
               if (encrypt_debug())
                       printf(">>>%s: No initial negotiation needed for type %s (%d)\r\n",
                               Name,
                               ENCTYPE_NAME_OK(type)
                                       ? ENCTYPE_NAME(type) : "(unknown)",
                               type);
               ret = 0;
       } else {
               ret = (*ep->is)(data, cnt);
               if (encrypt_debug())
                       printf("(*ep->is)(%p, %d) returned %s(%d)\n", data, cnt,
                               (ret < 0) ? "FAIL " :
                               (ret == 0) ? "SUCCESS " : "MORE_TO_DO ", ret);
       }
       if (ret < 0) {
               autodecrypt = 0;
       } else {
               decrypt_mode = type;
               if (ret == 0 && autodecrypt)
                       encrypt_send_request_start();
       }
}

void
encrypt_reply(unsigned char *data, int cnt)
{
       Encryptions *ep;
       register int ret, type;

       if (--cnt < 0)
               return;
       type = *data++;
       if (!(ep = findencryption(type))) {
               if (encrypt_debug())
                       printf(">>>%s: Can't find type %s (%d) for initial negotiation\r\n",
                               Name,
                               ENCTYPE_NAME_OK(type)
                                       ? ENCTYPE_NAME(type) : "(unknown)",
                               type);
               return;
       }
       if (!ep->reply) {
               if (encrypt_debug())
                       printf(">>>%s: No initial negotiation needed for type %s (%d)\r\n",
                               Name,
                               ENCTYPE_NAME_OK(type)
                                       ? ENCTYPE_NAME(type) : "(unknown)",
                               type);
               ret = 0;
       } else {
               ret = (*ep->reply)(data, cnt);
               if (encrypt_debug())
                       printf("(*ep->reply)(%p, %d) returned %s(%d)\n",
                               data, cnt,
                               (ret < 0) ? "FAIL " :
                               (ret == 0) ? "SUCCESS " : "MORE_TO_DO ", ret);
       }
       if (encrypt_debug())
               printf(">>>%s: encrypt_reply returned %d\n", Name, ret);
       if (ret < 0) {
               autoencrypt = 0;
       } else {
               encrypt_mode = type;
               if (ret == 0 && autoencrypt)
                       encrypt_start_output(type);
       }
}

/*
* Called when a ENCRYPT START command is received.
*/
void
encrypt_start(unsigned char *data, int cnt)
{
       Encryptions *ep;

       if (!decrypt_mode) {
               /*
                * Something is wrong.  We should not get a START
                * command without having already picked our
                * decryption scheme.  Send a REQUEST-END to
                * attempt to clear the channel...
                */
               printf("%s: Warning, Cannot decrypt input stream!!!\r\n", Name);
               encrypt_send_request_end();
               return;
       }

       if ((ep = finddecryption(decrypt_mode)) != NULL) {
               decrypt_input = ep->input;
               if (encrypt_verbose)
                       printf("[ Input is now decrypted with type %s ]\r\n",
                               ENCTYPE_NAME(decrypt_mode));
               if (encrypt_debug())
                       printf(">>>%s: Start to decrypt input with type %s\r\n",
                               Name, ENCTYPE_NAME(decrypt_mode));
       } else {
               printf("%s: Warning, Cannot decrypt type %s (%d)!!!\r\n",
                               Name,
                               ENCTYPE_NAME_OK(decrypt_mode)
                                       ? ENCTYPE_NAME(decrypt_mode)
                                       : "(unknown)",
                               decrypt_mode);
               encrypt_send_request_end();
       }
}

void
encrypt_session_key(Session_Key *key, int server)
{
       Encryptions *ep = encryptions;

       havesessionkey = 1;

       while (ep->type) {
               if (ep->session)
                       (*ep->session)(key, server);
#ifdef notdef
               if (!encrypt_output && autoencrypt && !server)
                       encrypt_start_output(ep->type);
               if (!decrypt_input && autodecrypt && !server)
                       encrypt_send_request_start();
#endif
               ++ep;
       }
}

/*
* Called when ENCRYPT END is received.
*/
void
encrypt_end(void)
{
       decrypt_input = 0;
       if (encrypt_debug())
               printf(">>>%s: Input is back to clear text\r\n", Name);
       if (encrypt_verbose)
               printf("[ Input is now clear text ]\r\n");
}

/*
* Called when ENCRYPT REQUEST-END is received.
*/
void
encrypt_request_end(void)
{
       encrypt_send_end();
}

/*
* Called when ENCRYPT REQUEST-START is received.  If we receive
* this before a type is picked, then that indicates that the
* other side wants us to start encrypting data as soon as we
* can.
*/
void
encrypt_request_start(unsigned char *data, int cnt)
{
       if (encrypt_mode == 0)  {
               if (Server)
                       autoencrypt = 1;
               return;
       }
       encrypt_start_output(encrypt_mode);
}

static unsigned char str_keyid[(MAXKEYLEN*2)+5] = { IAC, SB, TELOPT_ENCRYPT };

void
encrypt_enc_keyid(unsigned char *keyid, int len)
{
       encrypt_keyid(&ki[1], keyid, len);
}

void
encrypt_dec_keyid(unsigned char *keyid, int len)
{
       encrypt_keyid(&ki[0], keyid, len);
}

void
encrypt_keyid(struct key_info *kp, unsigned char *keyid, int len)
{
       Encryptions *ep;
       int dir = kp->dir;
       register int ret = 0;

       if (!(ep = (*kp->getcrypt)(*kp->modep))) {
               if (len == 0)
                       return;
               kp->keylen = 0;
       } else if (len == 0) {
               /*
                * Empty option, indicates a failure.
                */
               if (kp->keylen == 0)
                       return;
               kp->keylen = 0;
               if (ep->keyid)
                       (void)(*ep->keyid)(dir, kp->keyid, &kp->keylen);

       } else if ((size_t)len > sizeof(kp->keyid)) {
               return;
       } else if ((len != kp->keylen) ||
                  (memcmp(keyid, kp->keyid, len) != 0)) {
               /*
                * Length or contents are different
                */
               kp->keylen = len;
               memmove(kp->keyid, keyid, len);
               if (ep->keyid)
                       (void)(*ep->keyid)(dir, kp->keyid, &kp->keylen);
       } else {
               if (ep->keyid)
                       ret = (*ep->keyid)(dir, kp->keyid, &kp->keylen);
               if ((ret == 0) && (dir == DIR_ENCRYPT) && autoencrypt)
                       encrypt_start_output(*kp->modep);
               return;
       }

       encrypt_send_keyid(dir, kp->keyid, kp->keylen, 0);
}

void
encrypt_send_keyid(int dir, const unsigned char *keyid, int keylen, int saveit)
{
       unsigned char *strp;

       str_keyid[3] = (dir == DIR_ENCRYPT)
                       ? ENCRYPT_ENC_KEYID : ENCRYPT_DEC_KEYID;
       if (saveit) {
               struct key_info *kp = &ki[(dir == DIR_ENCRYPT) ? 0 : 1];
               memmove(kp->keyid, keyid, keylen);
               kp->keylen = keylen;
       }

       for (strp = &str_keyid[4]; keylen > 0; --keylen) {
               if ((*strp++ = *keyid++) == IAC)
                       *strp++ = IAC;
       }
       *strp++ = IAC;
       *strp++ = SE;
       telnet_net_write(str_keyid, strp - str_keyid);
       printsub('>', &str_keyid[2], strp - str_keyid - 2);
}

void
encrypt_auto(int on)
{
       if (on < 0)
               autoencrypt ^= 1;
       else
               autoencrypt = on ? 1 : 0;
}

void
decrypt_auto(int on)
{
       if (on < 0)
               autodecrypt ^= 1;
       else
               autodecrypt = on ? 1 : 0;
}

void
encrypt_start_output(int type)
{
       Encryptions *ep;
       register unsigned char *p;
       register int i;

       if (!(ep = findencryption(type))) {
               if (encrypt_debug()) {
                       printf(">>>%s: Can't encrypt with type %s (%d)\r\n",
                               Name,
                               ENCTYPE_NAME_OK(type)
                                       ? ENCTYPE_NAME(type) : "(unknown)",
                               type);
               }
               return;
       }
       if (ep->start) {
               i = (*ep->start)(DIR_ENCRYPT, Server);
               if (encrypt_debug()) {
                       printf(">>>%s: Encrypt start: %s (%d) %s\r\n",
                               Name,
                               (i < 0) ? "failed" :
                                       "initial negotiation in progress",
                               i, ENCTYPE_NAME(type));
               }
               if (i)
                       return;
       }
       p = str_start + 3;
       *p++ = ENCRYPT_START;
       for (i = 0; i < ki[0].keylen; ++i) {
               if ((*p++ = ki[0].keyid[i]) == IAC)
                       *p++ = IAC;
       }
       *p++ = IAC;
       *p++ = SE;
       telnet_net_write(str_start, p - str_start);
       net_encrypt();
       printsub('>', &str_start[2], p - &str_start[2]);
       /*
        * If we are already encrypting in some mode, then
        * encrypt the ring (which includes our request) in
        * the old mode, mark it all as "clear text" and then
        * switch to the new mode.
        */
       encrypt_output = ep->output;
       encrypt_mode = type;
       if (encrypt_debug())
               printf(">>>%s: Started to encrypt output with type %s\r\n",
                       Name, ENCTYPE_NAME(type));
       if (encrypt_verbose)
               printf("[ Output is now encrypted with type %s ]\r\n",
                       ENCTYPE_NAME(type));
}

void
encrypt_send_end(void)
{
       if (!encrypt_output)
               return;

       str_end[3] = ENCRYPT_END;
       telnet_net_write(str_end, sizeof(str_end));
       net_encrypt();
       printsub('>', &str_end[2], sizeof(str_end) - 2);
       /*
        * Encrypt the output buffer now because it will not be done by
        * netflush...
        */
       encrypt_output = 0;
       if (encrypt_debug())
               printf(">>>%s: Output is back to clear text\r\n", Name);
       if (encrypt_verbose)
               printf("[ Output is now clear text ]\r\n");
}

void
encrypt_send_request_start(void)
{
       register unsigned char *p;
       register int i;

       p = &str_start[3];
       *p++ = ENCRYPT_REQSTART;
       for (i = 0; i < ki[1].keylen; ++i) {
               if ((*p++ = ki[1].keyid[i]) == IAC)
                       *p++ = IAC;
       }
       *p++ = IAC;
       *p++ = SE;
       telnet_net_write(str_start, p - str_start);
       printsub('>', &str_start[2], p - &str_start[2]);
       if (encrypt_debug())
               printf(">>>%s: Request input to be encrypted\r\n", Name);
}

void
encrypt_send_request_end(void)
{
       str_end[3] = ENCRYPT_REQEND;
       telnet_net_write(str_end, sizeof(str_end));
       printsub('>', &str_end[2], sizeof(str_end) - 2);

       if (encrypt_debug())
               printf(">>>%s: Request input to be clear text\r\n", Name);
}

void
encrypt_wait(void)
{
       if (encrypt_debug())
               printf(">>>%s: in encrypt_wait\r\n", Name);
       if (!havesessionkey || !(I_SUPPORT_ENCRYPT & remote_supports_decrypt))
               return;
       while (autoencrypt && !encrypt_output)
               if (telnet_spin())
                       return;
}

int
encrypt_debug(void)
{
       return encrypt_debug_mode;
}

void
encrypt_gen_printsub(unsigned char *data, int cnt,
       unsigned char *buf, int buflen)
{
       char tbuf[16], *cp;

       cnt -= 2;
       data += 2;
       buf[buflen-1] = '\0';
       buf[buflen-2] = '*';
       buflen -= 2;
       for (; cnt > 0; cnt--, data++) {
               snprintf(tbuf, sizeof(tbuf), " %d", *data);
               for (cp = tbuf; *cp && buflen > 0; --buflen)
                       *buf++ = *cp++;
               if (buflen <= 0)
                       return;
       }
       *buf = '\0';
}

void
encrypt_printsub(unsigned char *data, int cnt,
       unsigned char *buf, int buflen)
{
       Encryptions *ep;
       register int type = data[1];

       for (ep = encryptions; ep->type && ep->type != type; ep++)
               ;

       if (ep->printsub)
               (*ep->printsub)(data, cnt, buf, buflen);
       else
               encrypt_gen_printsub(data, cnt, buf, buflen);
}
#endif  /* ENCRYPTION */

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