telnet.c

putty

		send_opt(telnet, (*o)->send, option);
		activate_option(telnet, *o);
		break;
	      case REALLY_INACTIVE:
		send_opt(telnet, (*o)->nsend, option);
		break;
	    }
	    return;
	} else if ((*o)->option == option && (*o)->nak == cmd) {
	    switch (telnet->opt_states[(*o)->index]) {
	      case REQUESTED:
		telnet->opt_states[(*o)->index] = INACTIVE;
		refused_option(telnet, *o);
		break;
	      case ACTIVE:
		telnet->opt_states[(*o)->index] = INACTIVE;
		send_opt(telnet, (*o)->nsend, option);
		option_side_effects(telnet, *o, 0);
		break;
	      case INACTIVE:
	      case REALLY_INACTIVE:
		break;
	    }
	    return;
	}
    }
    /*
     * If we reach here, the option was one we weren't prepared to
     * cope with. If the request was positive (WILL or DO), we send
     * a negative ack to indicate refusal. If the request was
     * negative (WONT / DONT), we must do nothing.
     */
    if (cmd == WILL || cmd == DO)
        send_opt(telnet, (cmd == WILL ? DONT : WONT), option);
}

static void process_subneg(Telnet telnet)
{
    unsigned char b[2048], *p, *q;
    int var, value, n;
    char *e;

    switch (telnet->sb_opt) {
      case TELOPT_TSPEED:
	if (telnet->sb_len == 1 && telnet->sb_buf[0] == TELQUAL_SEND) {
	    char *logbuf;
	    b[0] = IAC;
	    b[1] = SB;
	    b[2] = TELOPT_TSPEED;
	    b[3] = TELQUAL_IS;
	    strcpy((char *)(b + 4), telnet->cfg.termspeed);
	    n = 4 + strlen(telnet->cfg.termspeed);
	    b[n] = IAC;
	    b[n + 1] = SE;
	    telnet->bufsize = sk_write(telnet->s, (char *)b, n + 2);
	    logevent(telnet->frontend, "server:\tSB TSPEED SEND");
	    logbuf = dupprintf("client:\tSB TSPEED IS %s", telnet->cfg.termspeed);
	    logevent(telnet->frontend, logbuf);
	    sfree(logbuf);
	} else
	    logevent(telnet->frontend, "server:\tSB TSPEED <something weird>");
	break;
      case TELOPT_TTYPE:
	if (telnet->sb_len == 1 && telnet->sb_buf[0] == TELQUAL_SEND) {
	    char *logbuf;
	    b[0] = IAC;
	    b[1] = SB;
	    b[2] = TELOPT_TTYPE;
	    b[3] = TELQUAL_IS;
	    for (n = 0; telnet->cfg.termtype[n]; n++)
		b[n + 4] = (telnet->cfg.termtype[n] >= 'a'
			    && telnet->cfg.termtype[n] <=
			    'z' ? telnet->cfg.termtype[n] + 'A' -
			    'a' : telnet->cfg.termtype[n]);
	    b[n + 4] = IAC;
	    b[n + 5] = SE;
	    telnet->bufsize = sk_write(telnet->s, (char *)b, n + 6);
	    b[n + 4] = 0;
	    logevent(telnet->frontend, "server:\tSB TTYPE SEND");
	    logbuf = dupprintf("client:\tSB TTYPE IS %s", b + 4);
	    logevent(telnet->frontend, logbuf);
	    sfree(logbuf);
	} else
	    logevent(telnet->frontend, "server:\tSB TTYPE <something weird>\r\n");
	break;
      case TELOPT_OLD_ENVIRON:
      case TELOPT_NEW_ENVIRON:
	p = telnet->sb_buf;
	q = p + telnet->sb_len;
	if (p < q && *p == TELQUAL_SEND) {
	    char *logbuf;
	    p++;
	    logbuf = dupprintf("server:\tSB %s SEND", telopt(telnet->sb_opt));
	    logevent(telnet->frontend, logbuf);
	    sfree(logbuf);
	    if (telnet->sb_opt == TELOPT_OLD_ENVIRON) {
		if (telnet->cfg.rfc_environ) {
		    value = RFC_VALUE;
		    var = RFC_VAR;
		} else {
		    value = BSD_VALUE;
		    var = BSD_VAR;
		}
		/*
		 * Try to guess the sense of VAR and VALUE.
		 */
		while (p < q) {
		    if (*p == RFC_VAR) {
			value = RFC_VALUE;
			var = RFC_VAR;
		    } else if (*p == BSD_VAR) {
			value = BSD_VALUE;
			var = BSD_VAR;
		    }
		    p++;
		}
	    } else {
		/*
		 * With NEW_ENVIRON, the sense of VAR and VALUE
		 * isn't in doubt.
		 */
		value = RFC_VALUE;
		var = RFC_VAR;
	    }
	    b[0] = IAC;
	    b[1] = SB;
	    b[2] = telnet->sb_opt;
	    b[3] = TELQUAL_IS;
	    n = 4;
	    e = telnet->cfg.environmt;
	    while (*e) {
		b[n++] = var;
		while (*e && *e != '\t')
		    b[n++] = *e++;
		if (*e == '\t')
		    e++;
		b[n++] = value;
		while (*e)
		    b[n++] = *e++;
		e++;
	    }
	    if (*telnet->cfg.username) {
		b[n++] = var;
		b[n++] = 'U';
		b[n++] = 'S';
		b[n++] = 'E';
		b[n++] = 'R';
		b[n++] = value;
		e = telnet->cfg.username;
		while (*e)
		    b[n++] = *e++;
	    }
	    b[n++] = IAC;
	    b[n++] = SE;
	    telnet->bufsize = sk_write(telnet->s, (char *)b, n);
	    logbuf = dupprintf("client:\tSB %s IS %s%s%s%s",
			       telopt(telnet->sb_opt),
			       *telnet->cfg.username ? "USER=" : "",
			       telnet->cfg.username,
			       *telnet->cfg.username ? " " : "",
			       n == 6 ? "<nothing>" :
			       (*telnet->cfg.environmt ? "<stuff>" : ""));
	    logevent(telnet->frontend, logbuf);
	    sfree(logbuf);
	}
	break;
    }
}

static void do_telnet_read(Telnet telnet, char *buf, int len)
{
    char *outbuf = NULL;
    int outbuflen = 0, outbufsize = 0;

#define ADDTOBUF(c) do { \
    if (outbuflen >= outbufsize) { \
	outbufsize = outbuflen + 256; \
        outbuf = sresize(outbuf, outbufsize, char); \
    } \
    outbuf[outbuflen++] = (c); \
} while (0)

    while (len--) {
	int c = (unsigned char) *buf++;

	switch (telnet->state) {
	  case TOP_LEVEL:
	  case SEENCR:
	    if (c == NUL && telnet->state == SEENCR)
		telnet->state = TOP_LEVEL;
	    else if (c == IAC)
		telnet->state = SEENIAC;
	    else {
		if (!telnet->in_synch)
		    ADDTOBUF(c);

#if 1
		/* I can't get the F***ing winsock to insert the urgent IAC
		 * into the right position! Even with SO_OOBINLINE it gives
		 * it to recv too soon. And of course the DM byte (that
		 * arrives in the same packet!) appears several K later!!
		 *
		 * Oh well, we do get the DM in the right place so I'll
		 * just stop hiding on the next 0xf2 and hope for the best.
		 */
		else if (c == DM)
		    telnet->in_synch = 0;
#endif
		if (c == CR && telnet->opt_states[o_they_bin.index] != ACTIVE)
		    telnet->state = SEENCR;
		else
		    telnet->state = TOP_LEVEL;
	    }
	    break;
	  case SEENIAC:
	    if (c == DO)
		telnet->state = SEENDO;
	    else if (c == DONT)
		telnet->state = SEENDONT;
	    else if (c == WILL)
		telnet->state = SEENWILL;
	    else if (c == WONT)
		telnet->state = SEENWONT;
	    else if (c == SB)
		telnet->state = SEENSB;
	    else if (c == DM) {
		telnet->in_synch = 0;
		telnet->state = TOP_LEVEL;
	    } else {
		/* ignore everything else; print it if it's IAC */
		if (c == IAC) {
		    ADDTOBUF(c);
		}
		telnet->state = TOP_LEVEL;
	    }
	    break;
	  case SEENWILL:
	    proc_rec_opt(telnet, WILL, c);
	    telnet->state = TOP_LEVEL;
	    break;
	  case SEENWONT:
	    proc_rec_opt(telnet, WONT, c);
	    telnet->state = TOP_LEVEL;
	    break;
	  case SEENDO:
	    proc_rec_opt(telnet, DO, c);
	    telnet->state = TOP_LEVEL;
	    break;
	  case SEENDONT:
	    proc_rec_opt(telnet, DONT, c);
	    telnet->state = TOP_LEVEL;
	    break;
	  case SEENSB:
	    telnet->sb_opt = c;
	    telnet->sb_len = 0;
	    telnet->state = SUBNEGOT;
	    break;
	  case SUBNEGOT:
	    if (c == IAC)
		telnet->state = SUBNEG_IAC;
	    else {
	      subneg_addchar:
		if (telnet->sb_len >= telnet->sb_size) {
		    telnet->sb_size += SB_DELTA;
		    telnet->sb_buf = sresize(telnet->sb_buf, telnet->sb_size,
					     unsigned char);
		}
		telnet->sb_buf[telnet->sb_len++] = c;
		telnet->state = SUBNEGOT;	/* in case we came here by goto */
	    }
	    break;
	  case SUBNEG_IAC:
	    if (c != SE)
		goto subneg_addchar;   /* yes, it's a hack, I know, but... */
	    else {
		process_subneg(telnet);
		telnet->state = TOP_LEVEL;
	    }
	    break;
	}
    }

    if (outbuflen)
	c_write(telnet, outbuf, outbuflen);
    sfree(outbuf);
}

static void telnet_log(Plug plug, int type, SockAddr addr, int port,
		       const char *error_msg, int error_code)
{
    Telnet telnet = (Telnet) plug;
    char addrbuf[256], *msg;

    sk_getaddr(addr, addrbuf, lenof(addrbuf));

    if (type == 0)
	msg = dupprintf("Connecting to %s port %d", addrbuf, port);
    else
	msg = dupprintf("Failed to connect to %s: %s", addrbuf, error_msg);

    logevent(telnet->frontend, msg);
}

static int telnet_closing(Plug plug, const char *error_msg, int error_code,
			  int calling_back)
{
    Telnet telnet = (Telnet) plug;

    if (telnet->s) {
        sk_close(telnet->s);
        telnet->s = NULL;
	notify_remote_exit(telnet->frontend);
    }
    if (error_msg) {
	logevent(telnet->frontend, error_msg);
	connection_fatal(telnet->frontend, "%s", error_msg);
    }
    /* Otherwise, the remote side closed the connection normally. */
    return 0;
}

static int telnet_receive(Plug plug, int urgent, char *data, int len)
{
    Telnet telnet = (Telnet) plug;
    if (urgent)
	telnet->in_synch = TRUE;
    do_telnet_read(telnet, data, len);
    return 1;
}

static void telnet_sent(Plug plug, int bufsize)
{
    Telnet telnet = (Telnet) plug;
    telnet->bufsize = bufsize;
}

/*
 * Called to set up the Telnet connection.
 *
 * Returns an error message, or NULL on success.
 *
 * Also places the canonical host name into `realhost'. It must be
 * freed by the caller.
 */
static const char *telnet_init(void *frontend_handle, void **backend_handle,
			       Config *cfg,
			       char *host, int port, char **realhost,
			       int nodelay, int keepalive)
{
    static const struct plug_function_table fn_table = {
	telnet_log,
	telnet_closing,
	telnet_receive,
	telnet_sent
    };
    SockAddr addr;
    const char *err;
    Telnet telnet;

    telnet = snew(struct telnet_tag);
    telnet->fn = &fn_table;
    telnet->cfg = *cfg;		       /* STRUCTURE COPY */
    telnet->s = NULL;
    telnet->echoing = TRUE;
    telnet->editing = TRUE;
    telnet->activated = FALSE;
    telnet->sb_buf = NULL;
    telnet->sb_size = 0;
    telnet->frontend = frontend_handle;
    telnet->term_width = telnet->cfg.width;
    telnet->term_height = telnet->cfg.height;