state.c

经典的unix下telnetd代码

/*
 * suboption()
 *
 *	Look at the sub-option buffer, and try to be helpful to the other
 * side.
 *
 *	Currently we recognize:
 *
 *	Terminal type is
 *	Linemode
 *	Window size
 *	Terminal speed
 */
void
suboption(void)
{
    int subchar;

    DIAG(TD_OPTIONS, {netflush(); printsub('<', subpointer, SB_LEN()+2);});

    subchar = SB_GET();
    switch (subchar) {
    case TELOPT_TSPEED: {
	int xspeed, rspeed;

	if (his_state_is_wont(TELOPT_TSPEED))	/* Ignore if option disabled */
	    break;

	settimer(tspeedsubopt);

	if (SB_EOF() || SB_GET() != TELQUAL_IS)
	    return;

	xspeed = atoi((char *)subpointer);

	while (SB_GET() != ',' && !SB_EOF());
	if (SB_EOF())
	    return;

	rspeed = atoi((char *)subpointer);
	clientstat(TELOPT_TSPEED, xspeed, rspeed);

	break;

    }  /* end of case TELOPT_TSPEED */

    case TELOPT_TTYPE: {		/* Yaaaay! */
	char *tt;

	if (his_state_is_wont(TELOPT_TTYPE))	/* Ignore if option disabled */
	    break;
	settimer(ttypesubopt);

	if (SB_EOF() || SB_GET() != TELQUAL_IS) {
	    return;		/* ??? XXX but, this is the most robust */
	}

	tt = terminaltype;

	while ((tt < (terminaltype + sizeof terminaltype-1)) &&
	       !SB_EOF()) {
	    int c;

	    c = SB_GET();
	    if (isupper(c)) {
		c = tolower(c);
	    }
	    *tt++ = c;    /* accumulate name */
	}
	*tt = 0;
	break;
    }  /* end of case TELOPT_TTYPE */

    case TELOPT_NAWS: {
	int xwinsize, ywinsize;

	if (his_state_is_wont(TELOPT_NAWS))	/* Ignore if option disabled */
	    break;

	if (SB_EOF())
	    return;
	xwinsize = SB_GET() << 8;
	if (SB_EOF())
	    return;
	xwinsize |= SB_GET();
	if (SB_EOF())
	    return;
	ywinsize = SB_GET() << 8;
	if (SB_EOF())
	    return;
	ywinsize |= SB_GET();
	clientstat(TELOPT_NAWS, xwinsize, ywinsize);

	break;

    }  /* end of case TELOPT_NAWS */

    case TELOPT_STATUS: {
	int mode;

	if (SB_EOF())
	    break;
	mode = SB_GET();
	switch (mode) {
	case TELQUAL_SEND:
	    if (my_state_is_will(TELOPT_STATUS))
		send_status();
	    break;

	case TELQUAL_IS:
	    break;

	default:
	    break;
	}
	break;
    }  /* end of case TELOPT_STATUS */

    case TELOPT_XDISPLOC: {
	if (SB_EOF() || SB_GET() != TELQUAL_IS)
	    return;
	settimer(xdisplocsubopt);
	subpointer[SB_LEN()] = '\0';
	esetenv("DISPLAY", (char *)subpointer, 1);
	break;
    }  /* end of case TELOPT_XDISPLOC */

#ifdef	TELOPT_NEW_ENVIRON
    case TELOPT_NEW_ENVIRON:
#endif
    case TELOPT_OLD_ENVIRON: {
	int c;
	char *cp, *varp, *valp;

	if (SB_EOF())
	    return;
	c = SB_GET();
	if (c == TELQUAL_IS) {
	    if (subchar == TELOPT_OLD_ENVIRON)
		settimer(oenvironsubopt);
	    else
		settimer(environsubopt);
	} else if (c != TELQUAL_INFO) {
	    return;
	}

#ifdef	TELOPT_NEW_ENVIRON
	if (subchar == TELOPT_NEW_ENVIRON) {
	    while (!SB_EOF()) {
		c = SB_GET();
		if ((c == NEW_ENV_VAR) || (c == ENV_USERVAR))
		    break;
	    }
	} else
#endif
	    {
#ifdef	ENV_HACK
		/*
		 * We only want to do this if we haven't already decided
		 * whether or not the other side has its VALUE and VAR
		 * reversed.
		 */
		if (env_ovar < 0) {
		    int last = -1;		/* invalid value */
		    int empty = 0;
		    int got_var = 0, got_value = 0, got_uservar = 0;

		    /*
		     * The other side might have its VALUE and VAR values
		     * reversed.  To be interoperable, we need to determine
		     * which way it is.  If the first recognized character
		     * is a VAR or VALUE, then that will tell us what
		     * type of client it is.  If the fist recognized
		     * character is a USERVAR, then we continue scanning
		     * the suboption looking for two consecutive
		     * VAR or VALUE fields.  We should not get two
		     * consecutive VALUE fields, so finding two
		     * consecutive VALUE or VAR fields will tell us
		     * what the client is.
		     */
		    SB_SAVE();
		    while (!SB_EOF()) {
			c = SB_GET();
			switch(c) {
			case OLD_ENV_VAR:
			    if (last < 0 || last == OLD_ENV_VAR
				|| (empty && (last == OLD_ENV_VALUE)))
				goto env_ovar_ok;
			    got_var++;
			    last = OLD_ENV_VAR;
			    break;
			case OLD_ENV_VALUE:
			    if (last < 0 || last == OLD_ENV_VALUE
				|| (empty && (last == OLD_ENV_VAR)))
				goto env_ovar_wrong;
			    got_value++;
			    last = OLD_ENV_VALUE;
			    break;
			case ENV_USERVAR:
			    /* count strings of USERVAR as one */
			    if (last != ENV_USERVAR)
				got_uservar++;
			    if (empty) {
				if (last == OLD_ENV_VALUE)
				    goto env_ovar_ok;
				if (last == OLD_ENV_VAR)
				    goto env_ovar_wrong;
			    }
			    last = ENV_USERVAR;
			    break;
			case ENV_ESC:
			    if (!SB_EOF())
				c = SB_GET();
			    /* FALL THROUGH */
			default:
			    empty = 0;
			    continue;
			}
			empty = 1;
		    }
		    if (empty) {
			if (last == OLD_ENV_VALUE)
			    goto env_ovar_ok;
			if (last == OLD_ENV_VAR)
			    goto env_ovar_wrong;
		    }
		    /*
		     * Ok, the first thing was a USERVAR, and there
		     * are not two consecutive VAR or VALUE commands,
		     * and none of the VAR or VALUE commands are empty.
		     * If the client has sent us a well-formed option,
		     * then the number of VALUEs received should always
		     * be less than or equal to the number of VARs and
		     * USERVARs received.
		     *
		     * If we got exactly as many VALUEs as VARs and
		     * USERVARs, the client has the same definitions.
		     *
		     * If we got exactly as many VARs as VALUEs and
		     * USERVARS, the client has reversed definitions.
		     */
		    if (got_uservar + got_var == got_value) {
		    env_ovar_ok:
			env_ovar = OLD_ENV_VAR;
			env_ovalue = OLD_ENV_VALUE;
		    } else if (got_uservar + got_value == got_var) {
		    env_ovar_wrong:
			env_ovar = OLD_ENV_VALUE;
			env_ovalue = OLD_ENV_VAR;
			DIAG(TD_OPTIONS, {
			    output_data("ENVIRON VALUE and VAR are reversed!\r\n");
			});

		    }
		}
		SB_RESTORE();
#endif

		while (!SB_EOF()) {
		    c = SB_GET();
		    if ((c == env_ovar) || (c == ENV_USERVAR))
			break;
		}
	    }

	if (SB_EOF())
	    return;

	cp = varp = (char *)subpointer;
	valp = 0;

	while (!SB_EOF()) {
	    c = SB_GET();
	    if (subchar == TELOPT_OLD_ENVIRON) {
		if (c == env_ovar)
		    c = NEW_ENV_VAR;
		else if (c == env_ovalue)
		    c = NEW_ENV_VALUE;
	    }
	    switch (c) {

	    case NEW_ENV_VALUE:
		*cp = '\0';
		cp = valp = (char *)subpointer;
		break;

	    case NEW_ENV_VAR:
	    case ENV_USERVAR:
		*cp = '\0';
		if(envvarok(varp)) {
		    if (valp)
			esetenv(varp, valp, 1);
		    else
			unsetenv(varp);
		}
		cp = varp = (char *)subpointer;
		valp = 0;
		break;

	    case ENV_ESC:
		if (SB_EOF())
		    break;
		c = SB_GET();
		/* FALL THROUGH */
	    default:
		*cp++ = c;
		break;
	    }
	}
	*cp = '\0';
	if(envvarok(varp)) {
	    if (valp)
		esetenv(varp, valp, 1);
	    else
		unsetenv(varp);
	}
	break;
    }  /* end of case TELOPT_NEW_ENVIRON */
#ifdef AUTHENTICATION
    case TELOPT_AUTHENTICATION:
	if (SB_EOF())
	    break;
	switch(SB_GET()) {
	case TELQUAL_SEND:
	case TELQUAL_REPLY:
	    /*
	     * These are sent by us and cannot be sent by
	     * the client.
	     */
	    break;
	case TELQUAL_IS:
	    auth_is(subpointer, SB_LEN());
	    break;
	case TELQUAL_NAME:
	    auth_name(subpointer, SB_LEN());
	    break;
	}
	break;
#endif
#ifdef ENCRYPTION
    case TELOPT_ENCRYPT:
	if (SB_EOF())
	    break;
	switch(SB_GET()) {
	case ENCRYPT_SUPPORT:
	    encrypt_support(subpointer, SB_LEN());
	    break;
	case ENCRYPT_IS:
	    encrypt_is(subpointer, SB_LEN());
	    break;
	case ENCRYPT_REPLY:
	    encrypt_reply(subpointer, SB_LEN());
	    break;
	case ENCRYPT_START:
	    encrypt_start(subpointer, SB_LEN());
	    break;
	case ENCRYPT_END:
	    encrypt_end();
	    break;
	case ENCRYPT_REQSTART:
	    encrypt_request_start(subpointer, SB_LEN());
	    break;
	case ENCRYPT_REQEND:
	    /*
	     * We can always send an REQEND so that we cannot
	     * get stuck encrypting.  We should only get this
	     * if we have been able to get in the correct mode
	     * anyhow.
	     */
	    encrypt_request_end();
	    break;
	case ENCRYPT_ENC_KEYID:
	    encrypt_enc_keyid(subpointer, SB_LEN());
	    break;
	case ENCRYPT_DEC_KEYID:
	    encrypt_dec_keyid(subpointer, SB_LEN());
	    break;
	default:
	    break;
	}
	break;
#endif

    default:
	break;
    }  /* end of switch */

}  /* end of suboption */

void
doclientstat(void)
{
    clientstat(TELOPT_LINEMODE, WILL, 0);
}

#define	ADD(c)	 *ncp++ = c
#define	ADD_DATA(c) { *ncp++ = c; if (c == SE || c == IAC) *ncp++ = c; }

void
send_status(void)
{
    unsigned char statusbuf[256];
    unsigned char *ncp;
    unsigned char i;

    ncp = statusbuf;

    netflush();	/* get rid of anything waiting to go out */

    ADD(IAC);
    ADD(SB);
    ADD(TELOPT_STATUS);
    ADD(TELQUAL_IS);

    /*
     * We check the want_state rather than the current state,
     * because if we received a DO/WILL for an option that we
     * don't support, and the other side didn't send a DONT/WONT
     * in response to our WONT/DONT, then the "state" will be
     * WILL/DO, and the "want_state" will be WONT/DONT.  We
     * need to go by the latter.
     */
    for (i = 0; i < (unsigned char)NTELOPTS; i++) {
	if (my_want_state_is_will(i)) {
	    ADD(WILL);
	    ADD_DATA(i);
	}
	if (his_want_state_is_will(i)) {
	    ADD(DO);
	    ADD_DATA(i);
	}
    }

    if (his_want_state_is_will(TELOPT_LFLOW)) {
	ADD(SB);
	ADD(TELOPT_LFLOW);
	if (flowmode) {
	    ADD(LFLOW_ON);
	} else {
	    ADD(LFLOW_OFF);
	}
	ADD(SE);

	if (restartany >= 0) {
	    ADD(SB);
	    ADD(TELOPT_LFLOW);
	    if (restartany) {
		ADD(LFLOW_RESTART_ANY);
	    } else {
		ADD(LFLOW_RESTART_XON);
	    }
	    ADD(SE);
	}
    }


    ADD(IAC);
    ADD(SE);

    writenet(statusbuf, ncp - statusbuf);
    netflush();	/* Send it on its way */

    DIAG(TD_OPTIONS,
	 {printsub('>', statusbuf, ncp - statusbuf); netflush();});
}