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ver 4.1

/*************************************************************************
* (C) 2010 AITNET ltd - Sofia/Bulgaria - <misho@aitbg.com>
*  by Michael Pounov <misho@openbsd-bg.org>
*
* $Author: misho $
* $Id: telnet.c,v 1.5 2019/02/04 21:22:31 misho Exp $
*
**************************************************************************
The ELWIX and AITNET software is distributed under the following
terms:

All of the documentation and software included in the ELWIX and AITNET
Releases is copyrighted by ELWIX - Sofia/Bulgaria <info@elwix.org>

Copyright 2004 - 2017
	by Michael Pounov <misho@elwix.org>.  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. All advertising materials mentioning features or use of this software
   must display the following acknowledgement:
This product includes software developed by Michael Pounov <misho@elwix.org>
ELWIX - Embedded LightWeight unIX and its contributors.
4. Neither the name of AITNET 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 AITNET 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.
*/
#ifndef NDEBUG
	#define	TELOPTS
	#define	TELCMDS
#endif
#include "global.h"


/*
 * cli_telnetRecv() - Telnet receive commands, negotiate with telnet peer
 *
 * @sock = socket for communication
 * @attr = received attributes list, must be free after use, but if NULL receive in binary mode
 * @nAttr = received attributes list size, if is NULL receive in binary mode
 * @pdata = received data in supplied buffer
 * @datLen = buffer pdata size
 * return: 0 not present data; -1 error:: can`t read; -2 timeout; -3 EOF; >0 number of received bytes
*/
int
cli_telnetRecv(int sock, struct telnetAttrs **attr, int *nAttr, void *pdata, int datLen)
{
	int readLen, ret, pos;
	u_char buf[BUFSIZ], *data = NULL;
	struct telnetAttrs ta;
	register int i;
#ifdef SELECT_WAIT_FOR_READ
	fd_set fds;
	struct timeval tv = { DEFAULT_TELNET_TIMEOUT, 0 };
#endif

	if (attr && nAttr) {
		*attr = NULL;
		*nAttr = 0;
	}

	data = pdata ? pdata : NULL;
	if (!data || !datLen || BUFSIZ < datLen) {
		cli_SetErr(EINVAL, "Data buffer or size is not valid!");
		return -1;
	} else
		memset(data, 0, datLen);

#ifdef SELECT_WAIT_FOR_READ
	FD_ZERO(&fds);
	FD_SET(sock, &fds);
	if ((ret = select(sock + 1, &fds, NULL, NULL, &tv)) == -1) {
		LOGERR;
		return -1;
	}
	if (!ret) {
		cli_SetErr(ETIMEDOUT, "Timeout!");
		return -2;		// Timeout
	} else
		ret = 0;
#endif

	memset(buf, 0, BUFSIZ);
	readLen = read(sock, buf, BUFSIZ);
	if (-1 == readLen) {
		LOGERR;
		return -1;
	} else
		if (!readLen)
			return -3;	// EOF

	// receive in binary mode ...
	if (!attr || !nAttr) {
		memcpy(data, buf, readLen > datLen ? datLen : readLen);
		return readLen;
	}

	// telnet ascii mode ...
	for (ret = pos = i = 0; i < readLen && pos < datLen; i++) {
		// raw(clear) mode
		if (!ret) {
			if (IAC != buf[i]) {
				data[pos++] = buf[i];
			} else {
				ret = 1;
				memset(&ta, 0, sizeof ta);
			}

			continue;
		}

		// check for command
		if (1 == ret) {
			if (xEOF > buf[i]) {
				data[pos++] = buf[i - 1];
				data[pos++] = buf[i];

				goto cmd_exit;
			} else
				ta.ta_cmd = buf[i];
			if (SB > ta.ta_cmd) {
				(*nAttr)++;
				*attr = e_realloc(*attr, sizeof(struct telnetAttrs) * *nAttr);
				if (!*attr) {
					LOGERR;
					return -1;
				} else
					memcpy(&(*attr)[*nAttr - 1], &ta, sizeof(struct telnetAttrs));

				goto cmd_exit;
			}
			if (IAC > ta.ta_cmd) {
				ret = 2;
				continue;
			}
cmd_exit:
			ret = 0;
			continue;
		}

		// check for option
		if (2 == ret) {
			if (!(TELOPT_KERMIT >= buf[i]) && TELOPT_EXOPL != buf[i]) {
				data[pos++] = buf[i - 2];
				data[pos++] = buf[i - 1];
				data[pos++] = buf[i];

				goto opt_exit;
			} else
				ta.ta_opt = buf[i];
			if (SB != ta.ta_cmd) {
				(*nAttr)++;
				*attr = e_realloc(*attr, sizeof(struct telnetAttrs) * *nAttr);
				if (!*attr) {
					LOGERR;
					return -1;
				} else
					memcpy(&(*attr)[*nAttr - 1], &ta, sizeof(struct telnetAttrs));

				goto opt_exit;
			}

			ret = 3;
			continue;
opt_exit:
			ret = 0;
			continue;
		}

		// sub-option
		if (3 == ret) {
			if (ta.ta_sublen < MAX_SUB_LEN) {
				if (SE == buf[i] && IAC == ta.ta_sub[ta.ta_sublen - 1]) {
					ta.ta_sublen--;
					ta.ta_sub[ta.ta_sublen] = 0;

					(*nAttr)++;
					*attr = e_realloc(*attr, sizeof(struct telnetAttrs) * *nAttr);
					if (!*attr) {
						LOGERR;
						return -1;
					} else
						memcpy(&(*attr)[*nAttr - 1], &ta, sizeof(struct telnetAttrs));
					ret = 0;
				} else
					ta.ta_sub[ta.ta_sublen++] = buf[i];
			} else {
				cli_SetErr(EPROTONOSUPPORT, "Protocol limitation in sub-option to %d!", MAX_SUB_LEN);
				e_free(*attr);
				*nAttr = 0;
				return -1;
			}
		}
	}

	return pos;
}

#ifndef NDEBUG

/*
 * cli_telnet_DumpAttrs() - Telnet debug attributes list, if NDEBUG defined not include
 *
 * @attr = attributes list
 * @nAttr = attributes list size
 * return: none
*/
void
cli_telnet_DumpAttrs(struct telnetAttrs *attr, int nAttr)
{
	register int i;

	for (i = 0; i < nAttr; i++) {
		printf("DUMP:: Attribute(%d) = %s %s Sub(%d) => %s\n", i, 
				TELCMD(attr[i].ta_cmd), TELOPT(attr[i].ta_opt), 
				attr[i].ta_sublen, attr[i].ta_sub);
	}
}

#endif

/*
 * cli_telnetSend() - Telnet send commands, negotiate with telnet peer
 *
 * @sock = socket for communication
 * @attr = send attributes list
 * @nAttr = send attributes list size
 * @data = data for send
 * @datLen = data size
 * @Term = Terminate with GA (Go Ahead), 1 send after data GA command
 * return: 0 not sended commands; -1 error:: can`t send; >0 number of sended bytes
*/
int
cli_telnetSend(int sock, struct telnetAttrs *attr, int nAttr, void *data, int datLen, int Term)
{
	register int i;
	int writeLen, pos = 0, len = 0;
	u_char *buf = NULL;

	/* add commands */

	if (attr && nAttr) {
		for (i = 0; i < nAttr; i++) {
			len = 2;	// IAC CMD
			if (attr[i].ta_cmd > GA && attr[i].ta_cmd < IAC) {
				len++;	// added OPT

				if (SB == attr[i].ta_cmd) {
					len += 2; // added IAC SE to end ;)
					len += attr[i].ta_sublen;
				}
			}

			buf = e_realloc(buf, pos + len);
			if (!buf) {
				LOGERR;
				return -1;
			}

			buf[pos++] = IAC;
			buf[pos++] = attr[i].ta_cmd;
			if (attr[i].ta_cmd > GA && attr[i].ta_cmd < IAC) {
				buf[pos++] = attr[i].ta_opt;

				if (SB == attr[i].ta_cmd) {
					memcpy(buf + pos, attr[i].ta_sub, attr[i].ta_sublen);
					pos += attr[i].ta_sublen;
					buf[pos++] = IAC;
					buf[pos++] = SE;
				}
			}
		}
	}

	/* add data */

	if (data && datLen) {
		buf = e_realloc(buf, pos + datLen);
		if (!buf) {
			LOGERR;
			return -1;
		}

		memcpy(buf + pos, data, datLen);
		pos += datLen;
	}

	/* add GA after end of all */

	if (Term) {
		buf = e_realloc(buf, pos + 2);
		if (!buf) {
			LOGERR;
			return -1;
		}

		buf[pos++] = IAC;
		buf[pos++] = GA;
	}

	writeLen = write(sock, buf, pos);
	if (-1 == writeLen)
		LOGERR;

	if (buf)
		e_free(buf);
	return writeLen;
}


/*
 * cli_telnet_Get_SubOpt() - Telnet get sub option function
 *
 * @attr = input attribute
 * @code = sub-option code for opt
 * @data = sub-option data
 * @datLen = data size set max size in input, output return copy size
 * return: -1 can`t get option; !=-1 option code
*/
int
cli_telnet_Get_SubOpt(struct telnetAttrs *attr, u_char *code, void *data, u_char *datLen)
{
	u_char *pos, len;

	if (!attr || !data || !datLen || !*datLen)
		return -1;
	if (SB != attr->ta_cmd || !attr->ta_sublen) {
		cli_SetErr(ENOTSUP, "Wrong attribute argument!");
		return -1;
	} else {
		pos = attr->ta_sub;
		len = attr->ta_sublen;
	}

	memset(data, 0, *datLen);
	if (0xFF != *code) {
		*code = *pos++;
		len--;
	}

	*datLen = len > *datLen ? *datLen : len;
	memcpy(data, pos, *datLen);

	return attr->ta_opt;
}

/*
 * cli_telnet_Set_SubOpt() - Telnet set sub option function
 *
 * @attr = output attribute
 * @opt = attribute option
 * @code = sub-option code for opt, if 0xff not specified
 * @data = sub-option data, if NULL not specified
 * @datLen = data size, if 0 not specified
 * return: -1 can`t set sub-otion; 0 ok
*/
int
cli_telnet_Set_SubOpt(struct telnetAttrs *attr, u_char opt, u_char code, void *data, u_char datLen)
{
	u_char len;

	if (!attr)
		return -1;
	if (!(TELOPT_KERMIT >= opt) && TELOPT_EXOPL != opt) {
		cli_SetErr(EINVAL, "Invalid option argument!");
		return -1;
	}

	memset(attr, 0, sizeof(struct telnetAttrs));
	attr->ta_cmd = SB;
	attr->ta_opt = opt;

	if (0xFF != code) {
		attr->ta_sublen++;
		attr->ta_sub[0] = code;
	}

	if (data && datLen) {
		len = MAX_SUB_LEN > datLen ? datLen : MAX_SUB_LEN - 1;
		attr->ta_sublen += len;
		memcpy(attr->ta_sub + 1, data, len);
	}

	return 0;
}

/*
 * cli_telnet_GetCmd() - Telnet get command
 *
 * @attr = input attribute
 * return: -1 can`t get command; !=-1 command <<24 return sublen, <<8 return option, <<0 command
*/
u_int
cli_telnet_GetCmd(struct telnetAttrs *attr)
{
	u_int ret = 0;

	if (!attr)
		return -1;
	if (xEOF > attr->ta_cmd) {
		cli_SetErr(ENOTSUP, "Wrong attribute command argument!");
		return -1;
	}
	if (GA < attr->ta_cmd && !(TELOPT_KERMIT >= attr->ta_opt) && TELOPT_EXOPL != attr->ta_opt) {
		cli_SetErr(ENOTSUP, "Wrong attribute option argument!");
		return -1;
	}

	ret = attr->ta_sublen << 24;
	ret |= attr->ta_opt << 8;
	ret |= attr->ta_cmd;

	return ret;
}

/*
 * cli_telnet_SetCmd() - Telnet set command
 *
 * @attr = input attribute
 * @cmd = command
 * @optz = option, if 0xff not specified
 * @arg1 = sub-option code, if 0xff not specified
 * @arg2 = sub-option data, if NULL not specified
 * @arg3 = sub-option data size, if 0 not specified data
 * return: -1 can`t set command; !=-1 ok
*/
int
cli_telnet_SetCmd(struct telnetAttrs *attr, u_char cmd, int optz, ...)
{
	va_list lst;
	u_char res;
	void *ptr;

	if (!attr)
		return -1;
	else
		memset(attr, 0, sizeof(struct telnetAttrs));

	if (xEOF > cmd) {
		cli_SetErr(EINVAL, "Invalid command argument!");
		return -1;
	} else
		attr->ta_cmd = cmd;
	if (GA < attr->ta_cmd) {
		if (!(TELOPT_KERMIT >= attr->ta_opt) && TELOPT_EXOPL != attr->ta_opt) {
			cli_SetErr(EINVAL, "Invalid option argument!");
			return -1;
		} else
			attr->ta_opt = (u_char) optz;
	}
	if (SB == attr->ta_cmd) {
		va_start(lst, optz);
		res = (u_char) va_arg(lst, int);
		if (0xff != res) {
			*attr->ta_sub = res;
			attr->ta_sublen++;
		}
		ptr = va_arg(lst, void*);
		res = (u_char) va_arg(lst, int);
		if (ptr && MAX_SUB_LEN > res) {
			memcpy(attr->ta_sub + 1, ptr, res);
			attr->ta_sublen += res;
		}
		va_end(lst);
	}

	return 0;
}


/*
 * cli_telnet_Answer() - Automatic generate commands answer to send from telnet
 *
 * @caps = Array of capability options
 * @nCaps = number of capability options
 * @attr = input attribute
 * @nAttr = number of input attributes
 * @ans = output answered attributes, must be e_free() after use
 * @Ans = number of output answered attributes
 * return: -1 can`t answer; !=-1 ok
*/
int
cli_telnet_Answer(u_char *caps, int nCaps, struct telnetAttrs *attr, int nAttr, 
		struct telnetAttrs **ans, int *Ans)
{
	register int i, j;
	int flg;
	struct telnetAttrs ta;

	if (!caps || !nCaps || !attr || !nAttr || !ans || !Ans)
		return -1;
	else {
		*ans = NULL;
		*Ans = 0;
	}

	for (i = 0; i < nAttr; i++) {
		if (SB > attr[i].ta_cmd || IAC == attr[i].ta_cmd || DONT == attr[i].ta_cmd || WONT == attr[i].ta_cmd)
			continue;

		for (flg = -1, j = 0; j < nCaps; j++) {
			if (!(TELOPT_KERMIT >= CAP(caps[j])) && TELOPT_EXOPL != CAP(caps[j]))
				continue;

			if (attr[i].ta_opt == CAP(caps[j])) {
				flg = j;
				break;
			}
		}

		// make attribute ...
		if (flg > -1) {
			(*Ans)++;
			*ans = e_realloc(*ans, sizeof(struct telnetAttrs) * *Ans);
			if (!*ans) {
				LOGERR;
				return -1;
			} else
				memset(&ta, 0, sizeof ta);

			ta.ta_opt = attr[i].ta_opt;
			switch (attr[i].ta_cmd) {
				case DO:
					ta.ta_cmd = SUP_CAPS(caps[flg]) ? WILL : WONT;
					break;
				case WILL:
					ta.ta_cmd = SUP_CAPS(caps[flg]) ? DO : DONT;
					break;
				case SB:
					ta.ta_cmd = SB;
					break;
			}

			memcpy(&(*ans)[*Ans - 1], &ta, sizeof(struct telnetAttrs));
		}
	}

	return 0;
}