state.c

早期freebsd实现

/*
 * 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. 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.
 */

#ifndef lint
static char sccsid[] = "@(#)state.c	8.2 (Berkeley) 12/15/93";
#endif /* not lint */

#include "telnetd.h"
#if	defined(AUTHENTICATION)
#include <libtelnet/auth.h>
#endif

unsigned char	doopt[] = { IAC, DO, '%', 'c', 0 };
unsigned char	dont[] = { IAC, DONT, '%', 'c', 0 };
unsigned char	will[] = { IAC, WILL, '%', 'c', 0 };
unsigned char	wont[] = { IAC, WONT, '%', 'c', 0 };
int	not42 = 1;

/*
 * Buffer for sub-options, and macros
 * for suboptions buffer manipulations
 */
unsigned char subbuffer[512], *subpointer= subbuffer, *subend= subbuffer;

#define	SB_CLEAR()	subpointer = subbuffer
#define	SB_TERM()	{ subend = subpointer; SB_CLEAR(); }
#define	SB_ACCUM(c)	if (subpointer < (subbuffer+sizeof subbuffer)) { \
				*subpointer++ = (c); \
			}
#define	SB_GET()	((*subpointer++)&0xff)
#define	SB_EOF()	(subpointer >= subend)
#define	SB_LEN()	(subend - subpointer)

#ifdef	ENV_HACK
unsigned char *subsave;
#define SB_SAVE()	subsave = subpointer;
#define	SB_RESTORE()	subpointer = subsave;
#endif


/*
 * State for recv fsm
 */
#define	TS_DATA		0	/* base state */
#define	TS_IAC		1	/* look for double IAC's */
#define	TS_CR		2	/* CR-LF ->'s CR */
#define	TS_SB		3	/* throw away begin's... */
#define	TS_SE		4	/* ...end's (suboption negotiation) */
#define	TS_WILL		5	/* will option negotiation */
#define	TS_WONT		6	/* wont " */
#define	TS_DO		7	/* do " */
#define	TS_DONT		8	/* dont " */

	void
telrcv()
{
	register int c;
	static int state = TS_DATA;
#if	defined(CRAY2) && defined(UNICOS5)
	char *opfrontp = pfrontp;
#endif

	while (ncc > 0) {
		if ((&ptyobuf[BUFSIZ] - pfrontp) < 2)
			break;
		c = *netip++ & 0377, ncc--;
#ifdef	ENCRYPTION
		if (decrypt_input)
			c = (*decrypt_input)(c);
#endif	/* ENCRYPTION */
		switch (state) {

		case TS_CR:
			state = TS_DATA;
			/* Strip off \n or \0 after a \r */
			if ((c == 0) || (c == '\n')) {
				break;
			}
			/* FALL THROUGH */

		case TS_DATA:
			if (c == IAC) {
				state = TS_IAC;
				break;
			}
			/*
			 * We now map \r\n ==> \r for pragmatic reasons.
			 * Many client implementations send \r\n when
			 * the user hits the CarriageReturn key.
			 *
			 * We USED to map \r\n ==> \n, since \r\n says
			 * that we want to be in column 1 of the next
			 * printable line, and \n is the standard
			 * unix way of saying that (\r is only good
			 * if CRMOD is set, which it normally is).
			 */
			if ((c == '\r') && his_state_is_wont(TELOPT_BINARY)) {
				int nc = *netip;
#ifdef	ENCRYPTION
				if (decrypt_input)
					nc = (*decrypt_input)(nc & 0xff);
#endif	/* ENCRYPTION */
#ifdef	LINEMODE
				/*
				 * If we are operating in linemode,
				 * convert to local end-of-line.
				 */
				if (linemode && (ncc > 0) && (('\n' == nc) ||
					 ((0 == nc) && tty_iscrnl())) ) {
					netip++; ncc--;
					c = '\n';
				} else
#endif
				{
#ifdef	ENCRYPTION
					if (decrypt_input)
						(void)(*decrypt_input)(-1);
#endif	/* ENCRYPTION */
					state = TS_CR;
				}
			}
			*pfrontp++ = c;
			break;

		case TS_IAC:
gotiac:			switch (c) {

			/*
			 * Send the process on the pty side an
			 * interrupt.  Do this with a NULL or
			 * interrupt char; depending on the tty mode.
			 */
			case IP:
				DIAG(TD_OPTIONS,
					printoption("td: recv IAC", c));
				interrupt();
				break;

			case BREAK:
				DIAG(TD_OPTIONS,
					printoption("td: recv IAC", c));
				sendbrk();
				break;

			/*
			 * Are You There?
			 */
			case AYT:
				DIAG(TD_OPTIONS,
					printoption("td: recv IAC", c));
				recv_ayt();
				break;

			/*
			 * Abort Output
			 */
			case AO:
			    {
				DIAG(TD_OPTIONS,
					printoption("td: recv IAC", c));
				ptyflush();	/* half-hearted */
				init_termbuf();

				if (slctab[SLC_AO].sptr &&
				    *slctab[SLC_AO].sptr != (cc_t)(_POSIX_VDISABLE)) {
				    *pfrontp++ =
					(unsigned char)*slctab[SLC_AO].sptr;
				}

				netclear();	/* clear buffer back */
				*nfrontp++ = IAC;
				*nfrontp++ = DM;
				neturg = nfrontp-1; /* off by one XXX */
				DIAG(TD_OPTIONS,
					printoption("td: send IAC", DM));
				break;
			    }

			/*
			 * Erase Character and
			 * Erase Line
			 */
			case EC:
			case EL:
			    {
				cc_t ch;

				DIAG(TD_OPTIONS,
					printoption("td: recv IAC", c));
				ptyflush();	/* half-hearted */
				init_termbuf();
				if (c == EC)
					ch = *slctab[SLC_EC].sptr;
				else
					ch = *slctab[SLC_EL].sptr;
				if (ch != (cc_t)(_POSIX_VDISABLE))
					*pfrontp++ = (unsigned char)ch;
				break;
			    }

			/*
			 * Check for urgent data...
			 */
			case DM:
				DIAG(TD_OPTIONS,
					printoption("td: recv IAC", c));
				SYNCHing = stilloob(net);
				settimer(gotDM);
				break;


			/*
			 * Begin option subnegotiation...
			 */
			case SB:
				state = TS_SB;
				SB_CLEAR();
				continue;

			case WILL:
				state = TS_WILL;
				continue;

			case WONT:
				state = TS_WONT;
				continue;

			case DO:
				state = TS_DO;
				continue;

			case DONT:
				state = TS_DONT;
				continue;
			case EOR:
				if (his_state_is_will(TELOPT_EOR))
					doeof();
				break;

			/*
			 * Handle RFC 10xx Telnet linemode option additions
			 * to command stream (EOF, SUSP, ABORT).
			 */
			case xEOF:
				doeof();
				break;

			case SUSP:
				sendsusp();
				break;

			case ABORT:
				sendbrk();
				break;

			case IAC:
				*pfrontp++ = c;
				break;
			}
			state = TS_DATA;
			break;

		case TS_SB:
			if (c == IAC) {
				state = TS_SE;
			} else {
				SB_ACCUM(c);
			}
			break;

		case TS_SE:
			if (c != SE) {
				if (c != IAC) {
					/*
					 * bad form of suboption negotiation.
					 * handle it in such a way as to avoid
					 * damage to local state.  Parse
					 * suboption buffer found so far,
					 * then treat remaining stream as
					 * another command sequence.
					 */

					/* for DIAGNOSTICS */
					SB_ACCUM(IAC);
					SB_ACCUM(c);
					subpointer -= 2;

					SB_TERM();
					suboption();
					state = TS_IAC;
					goto gotiac;
				}
				SB_ACCUM(c);
				state = TS_SB;
			} else {
				/* for DIAGNOSTICS */
				SB_ACCUM(IAC);
				SB_ACCUM(SE);
				subpointer -= 2;

				SB_TERM();
				suboption();	/* handle sub-option */
				state = TS_DATA;
			}
			break;

		case TS_WILL:
			willoption(c);
			state = TS_DATA;
			continue;

		case TS_WONT:
			wontoption(c);
			state = TS_DATA;
			continue;

		case TS_DO:
			dooption(c);
			state = TS_DATA;
			continue;

		case TS_DONT:
			dontoption(c);
			state = TS_DATA;
			continue;

		default:
			syslog(LOG_ERR, "telnetd: panic state=%d\n", state);
			printf("telnetd: panic state=%d\n", state);
			exit(1);
		}
	}
#if	defined(CRAY2) && defined(UNICOS5)
	if (!linemode) {
		char	xptyobuf[BUFSIZ+NETSLOP];
		char	xbuf2[BUFSIZ];
		register char *cp;
		int n = pfrontp - opfrontp, oc;
		bcopy(opfrontp, xptyobuf, n);
		pfrontp = opfrontp;
		pfrontp += term_input(xptyobuf, pfrontp, n, BUFSIZ+NETSLOP,
					xbuf2, &oc, BUFSIZ);
		for (cp = xbuf2; oc > 0; --oc)
			if ((*nfrontp++ = *cp++) == IAC)
				*nfrontp++ = IAC;
	}
#endif	/* defined(CRAY2) && defined(UNICOS5) */
}  /* end of telrcv */

/*
 * The will/wont/do/dont state machines are based on Dave Borman's
 * Telnet option processing state machine.
 *
 * These correspond to the following states:
 *	my_state = the last negotiated state
 *	want_state = what I want the state to go to
 *	want_resp = how many requests I have sent
 * All state defaults are negative, and resp defaults to 0.
 *
 * When initiating a request to change state to new_state:
 * 
 * if ((want_resp == 0 && new_state == my_state) || want_state == new_state) {
 *	do nothing;
 * } else {
 *	want_state = new_state;
 *	send new_state;
 *	want_resp++;
 * }
 *
 * When receiving new_state:
 *
 * if (want_resp) {
 *	want_resp--;
 *	if (want_resp && (new_state == my_state))
 *		want_resp--;
 * }
 * if ((want_resp == 0) && (new_state != want_state)) {
 *	if (ok_to_switch_to new_state)
 *		want_state = new_state;
 *	else
 *		want_resp++;
 *	send want_state;
 * }
 * my_state = new_state;
 *
 * Note that new_state is implied in these functions by the function itself.
 * will and do imply positive new_state, wont and dont imply negative.
 *
 * Finally, there is one catch.  If we send a negative response to a
 * positive request, my_state will be the positive while want_state will
 * remain negative.  my_state will revert to negative when the negative
 * acknowlegment arrives from the peer.  Thus, my_state generally tells
 * us not only the last negotiated state, but also tells us what the peer
 * wants to be doing as well.  It is important to understand this difference
 * as we may wish to be processing data streams based on our desired state
 * (want_state) or based on what the peer thinks the state is (my_state).
 *
 * This all works fine because if the peer sends a positive request, the data
 * that we receive prior to negative acknowlegment will probably be affected
 * by the positive state, and we can process it as such (if we can; if we
 * can't then it really doesn't matter).  If it is that important, then the
 * peer probably should be buffering until this option state negotiation
 * is complete.
 *
 */
	void
send_do(option, init)
	int option, init;
{
	if (init) {
		if ((do_dont_resp[option] == 0 && his_state_is_will(option)) ||
		    his_want_state_is_will(option))
			return;
		/*
		 * Special case for TELOPT_TM:  We send a DO, but pretend
		 * that we sent a DONT, so that we can send more DOs if
		 * we want to.
		 */
		if (option == TELOPT_TM)
			set_his_want_state_wont(option);
		else
			set_his_want_state_will(option);
		do_dont_resp[option]++;
	}
	(void) sprintf(nfrontp, (char *)doopt, option);
	nfrontp += sizeof (dont) - 2;

	DIAG(TD_OPTIONS, printoption("td: send do", option));
}

#ifdef	AUTHENTICATION
extern void auth_request();
#endif
#ifdef	LINEMODE
extern void doclientstat();
#endif
#ifdef	ENCRYPTION
extern void encrypt_send_support();
#endif	/* ENCRYPTION */

	void
willoption(option)
	int option;
{
	int changeok = 0;
	void (*func)() = 0;

	/*
	 * process input from peer.
	 */

	DIAG(TD_OPTIONS, printoption("td: recv will", option));

	if (do_dont_resp[option]) {
		do_dont_resp[option]--;
		if (do_dont_resp[option] && his_state_is_will(option))
			do_dont_resp[option]--;
	}
	if (do_dont_resp[option] == 0) {
	    if (his_want_state_is_wont(option)) {
		switch (option) {

		case TELOPT_BINARY:
			init_termbuf();
			tty_binaryin(1);
			set_termbuf();
			changeok++;
			break;

		case TELOPT_ECHO:
			/*
			 * See comments below for more info.
			 */
			not42 = 0;	/* looks like a 4.2 system */
			break;

		case TELOPT_TM:
#if	defined(LINEMODE) && defined(KLUDGELINEMODE)
			/*
			 * This telnetd implementation does not really
			 * support timing marks, it just uses them to
			 * support the kludge linemode stuff.  If we
			 * receive a will or wont TM in response to our
			 * do TM request that may have been sent to
			 * determine kludge linemode support, process
			 * it, otherwise TM should get a negative
			 * response back.
			 */
			/*
			 * Handle the linemode kludge stuff.
			 * If we are not currently supporting any
			 * linemode at all, then we assume that this
			 * is the client telling us to use kludge
			 * linemode in response to our query.  Set the
			 * linemode type that is to be supported, note
			 * that the client wishes to use linemode, and
			 * eat the will TM as though it never arrived.
			 */
			if (lmodetype < KLUDGE_LINEMODE) {
				lmodetype = KLUDGE_LINEMODE;
				clientstat(TELOPT_LINEMODE, WILL, 0);
				send_wont(TELOPT_SGA, 1);
			} else if (lmodetype == NO_AUTOKLUDGE) {
				lmodetype = KLUDGE_OK;
			}
#endif	/* defined(LINEMODE) && defined(KLUDGELINEMODE) */
			/*
			 * We never respond to a WILL TM, and
			 * we leave the state WONT.
			 */
			return;