state.c

linux下telnet服务端的源码实现

  DEBUG(debug_options, 1, printsub ('<', subpointer, SB_LEN () + 2));

  subchar = SB_GET ();
  switch (subchar)
    {
    case TELOPT_TSPEED:
      {
	register 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:
      {				
	static struct obstack stk;
	char *p;
	
	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 */

	if (terminaltype)
	  free (terminaltype);
	
	obstack_init (&stk);
	while (!SB_EOF ())
	  {
	    int c = tolower (SB_GET ());
	    obstack_1grow (&stk, c);
	  }
	obstack_1grow (&stk, 0);
	p = obstack_finish (&stk);
	terminaltype = xstrdup (p);
	obstack_free (&stk, NULL);
	break;
      }				/* end of case TELOPT_TTYPE */

    case TELOPT_NAWS:
      {
	register 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_LINEMODE:
      {
	register int request;

	/* Ignore if option disabled */
	if (his_state_is_wont (TELOPT_LINEMODE)) 
	  break;
	/*
	 * Process linemode suboptions.
	 */
	if (SB_EOF ())
	  break;		/* garbage was sent */
	request = SB_GET ();	/* get will/wont */

	if (SB_EOF ())
	  break;		/* another garbage check */

	if (request == LM_SLC)
	  {			/* SLC is not preceeded by WILL or WONT */
	    /*
	     * Process suboption buffer of slc's
	     */
	    start_slc (1);
	    do_opt_slc (subpointer, subend - subpointer);
	    end_slc (0);
	    break;
	  }
	else if (request == LM_MODE)
	  {
	    if (SB_EOF ())
	      return;
	    useeditmode = SB_GET ();	/* get mode flag */
	    clientstat (LM_MODE, 0, 0);
	    break;
	  }

	if (SB_EOF ())
	  break;
	switch (SB_GET ())
	  {			/* what suboption? */
	  case LM_FORWARDMASK:
	    /*
	     * According to spec, only server can send request for
	     * forwardmask, and client can only return a positive response.
	     * So don't worry about it.
	     */

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

    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';
	setenv ("DISPLAY", (char *) subpointer, 1);
	break;
      }				/* end of case TELOPT_XDISPLOC */

#ifdef	TELOPT_NEW_ENVIRON
    case TELOPT_NEW_ENVIRON:
#endif
    case TELOPT_OLD_ENVIRON:
      {
	register int c;
	register 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)
	      {
		register 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;
		    DEBUG(debug_options, 1,
			  debug_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 (valp)
		  (void) setenv (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 (valp)
	  (void) setenv (varp, valp, 1);
	else
	  unsetenv (varp);
	break;
      }				/* end of case TELOPT_NEW_ENVIRON */
#if	defined(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 /* ENCRYPTION */

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

}				/* end of suboption */

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

void
send_status ()
{
#define ADD(c) \
        do { \
                if (ep > ncp) \
                        *ncp++ = c; \
                else \
                        goto trunc; \
        } while (0)
#define ADD_DATA(c) \
        do { \
                ADD(c); if (c == SE || c == IAC) ADD(c); \
        } while (0)

  unsigned char statusbuf[256];
  unsigned char *ep;
  register unsigned char *ncp;
  register unsigned char i;

  ncp = statusbuf;
  ep = statusbuf + sizeof (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);
	}
    }

  if (his_want_state_is_will (TELOPT_LINEMODE))
    {
      unsigned char *cp, *cpe;
      int len;

      ADD (SB);
      ADD (TELOPT_LINEMODE);
      ADD (LM_MODE);
      ADD_DATA (editmode);
      ADD (SE);

      ADD (SB);
      ADD (TELOPT_LINEMODE);
      ADD (LM_SLC);
      start_slc (0);
      send_slc ();
      len = end_slc (&cp);
      for (cpe = cp + len; cp < cpe; cp++)
	ADD_DATA (*cp);
      ADD (SE);
    }

  ADD (IAC);
  ADD (SE);

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

  DEBUG(debug_options, 1, printsub ('>', statusbuf, ncp - statusbuf));
  return;

trunc:
  /* XXX bark? */
  return;
#undef ADD
#undef ADD_DATA
}