/*****************************************************************************
 *
 * $id$
 * Purpose ...............: Telnet IO filter
 *
 *****************************************************************************
 * Copyright (C) 1997-2003
 *   
 * Michiel Broek		FIDO:	2:280/2802
 * Beekmansbos 10
 * 1971 BV IJmuiden
 * the Netherlands
 *
 * This file is part of MBSE BBS.
 *
 * This BBS 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 2, or (at your option) any
 * later version.
 *
 * MBSE BBS 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 MBSE BBS; see the file COPYING.  If not, write to the Free
 * Software Foundation, 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
 *****************************************************************************/


#include "../config.h"
#include "../lib/libs.h"
#include "../lib/clcomm.h"
#include "hydra.h"
#include "telnio.h"


static int	tellen;



/* --- This is an artwork of serge terekhov, 2:5000/13@fidonet :) --- */

void telnet_answer(int tag, int opt)
{
    char    buf[3];
    char    *r = (char *)"???";
	
    switch (tag) {
	case WILL:
	    r = (char *)"WILL";
	    break;
	case WONT:
	    r = (char *)"WONT";
	    break;
	case DO:
	    r = (char *)"DO";
	    break;
	case DONT:
	    r = (char *)"DONT";
	    break;
    }
    Syslog('s', "TELNET send %s %d", r, opt);

    buf[0] = IAC;
    buf[1] = tag;
    buf[2] = opt;
    if (write (1, buf, 3) != 3)
	WriteError("$answer cant send");
}



int telnet_init(void)
{
    Syslog('s', "telnet_init()");
    tellen = 0;
    telnet_answer(DO, TOPT_SUPP);
    telnet_answer(WILL, TOPT_SUPP);
    telnet_answer(DO, TOPT_BIN);
    telnet_answer(WILL, TOPT_BIN);
    telnet_answer(DO, TOPT_ECHO);
    telnet_answer(WILL, TOPT_ECHO);
    return 1;
}



/*
 * Read function for mbtelnetd
 */
int telnet_read(char *buf, int len)
{
    int		n = 0, m;
    char	*q, *p;
    static char	telbuf[4];

    Syslog('s', "telnet_read(buf, %d tellen=%d)", len, tellen);
    while ((n == 0) && (n = read (0, buf + tellen, H_ZIPBUFLEN - tellen)) > 0) {

	Syslog('s', " n=%d tellen=%d", n, tellen);
	if (n < 0) {
	    Syslog('s', "telnet_read n=%d", n);
	    return n;
	}

	if (tellen) {
	    Syslog('s', " memcpy");
	    memcpy(buf, telbuf, tellen);
	    n += tellen;
	    tellen = 0;
	}

	if (memchr (buf, IAC, n)) {
	    Syslog('s', " IAC detected");
	    for (p = q = buf; n--; )
		if ((m = (unsigned char)*q++) != IAC)
		    *p++ = m;
		else {
		    if (n < 2) {
			memcpy (telbuf, q - 1, tellen = n + 1);
			break;
		    }
		    --n;
		    switch (m = (unsigned char)*q++) {
			case WILL:  m = (unsigned char)*q++; --n;
				    Syslog('s', "TELNET: recv WILL %d", m);
				    if (m != TOPT_BIN && m != TOPT_SUPP && m != TOPT_ECHO)
					telnet_answer(DONT, m);
				    break;
			case WONT:  m = *q++; 
				    --n;
				    Syslog('s', "TELNET: recv WONT %d", m);
				    break;
			case DO:    m = (unsigned char)*q++; 
				    --n;
				    Syslog('s', "TELNET: recv DO %d", m);
				    if (m != TOPT_BIN && m != TOPT_SUPP && m != TOPT_ECHO)
					telnet_answer(WONT, m);
				    break;
			case DONT:  m = (unsigned char)*q++; 
				    --n;
				    Syslog('s', "TELNET: recv DONT %d", m);
				    break;
			case IAC:   Syslog('s', "TELNET: recv 2nd IAC %d", m);
				    *p++ = IAC;
				    break;
			default:    Syslog('s', "TELNET: recv IAC %d", m);
				    break;
		    }
		}
	    n = p - buf;
	}
    }

    Syslog('s', " return n=%d", n);
    return n;
}



/*
 * Telnet output filter, IAC characters are escaped.
 */
int telnet_write(char *buf, int len)
{
    char    *q;
    int	    k, l;
    
    Syslog('s', "telnet_write(buf, %d)", len);
    l = len;
    while ((len > 0) && (q = memchr(buf, IAC, len))) {
	k = (q - buf) + 1;
	if ((write(1, buf, k) != k) || (write(1, q, 1) != 1)) {
	    return -1;
	}
	buf += k;
	len -= k;
    }

    if ((len > 0) && write(1, buf, len) != len) {
	return -1;
    }
    return l;
}



int telnet_buffer(char *buf, int len)
{
    int	    i, j, m = 0, rc;

    rc = len;

    if (memchr (buf, IAC, rc)) {
	Syslog('s', "telnet_buffer: IAC in input stream rc=%d", rc);
//	Syslogp('s', printable(buf, rc));
	j = 0;
	for (i = 0; i < rc; i++) {
	    if ((buf[i] & 0xff) == IAC) {
		i++;
		switch (buf[i] & 0xff) {
		    case WILL:  i++;
				m = buf[i] & 0xff;
				Syslog('s', "Telnet recv WILL %d", m);
				if (m != TOPT_BIN && m != TOPT_SUPP && m != TOPT_ECHO)
				    telnet_answer(DONT, m);
				break;
		    case WONT:  i++;
				m = buf[i] & 0xff;
				Syslog('s', "Telnet recv WONT %d", m);
				break;
		    case DO:    i++;
				m = buf[i] & 0xff;
				Syslog('s', "Telnet recv DO %d", m);
				if (m != TOPT_BIN && m != TOPT_SUPP && m != TOPT_ECHO)
				    telnet_answer(WONT, m);
				break;
		    case DONT:  i++;
				m = buf[i] & 0xff;
				Syslog('s', "Telnet recv DONT %d", m);
				break;
		    case IAC:   buf[j] = buf[i];
				j++;
				Syslog('s', "Telnet recv escaped IAC");
				break;
		    default:    m = buf[i] & 0xff;
				Syslog('s', "TELNET: recv IAC %d, this is not good", m);
				buf[j] = IAC;
				j++;
				buf[j] = m;
				j++;
				break;
		}
	    } else {
		buf[j] = buf[i];
		j++;
	    }
	}
	rc = j;
//	Syslog('s', "new rc=%d", rc);
//	Syslogp('s', printable(buf, rc));
    }

    return rc;
}