int proxy_http_negotiate (ProxySocket *p, int change)
{
    if (p->state == PROXY_STATE_NEW) {
	/* we are just beginning the proxy negotiate process,
	 * so we'll send off the initial bits of the request.
	 * for this proxy method, it's just a simple HTTP
	 * request
	 */
	char *buf, dest[512];
	char *username, *password;

	sk_getaddr(p->remote_addr, dest, lenof(dest));

	buf = dupprintf("CONNECT %s:%i HTTP/1.1\r\nHost: %s:%i\r\n",
			dest, p->remote_port, dest, p->remote_port);
	sk_write(p->sub_socket, buf, strlen(buf));
	sfree(buf);

	username = conf_get_str(p->conf, CONF_proxy_username);
	password = conf_get_str(p->conf, CONF_proxy_password);
	if (username[0] || password[0]) {
	    char *buf, *buf2;
	    int i, j, len;
	    buf = dupprintf("%s:%s", username, password);
	    len = strlen(buf);
	    buf2 = snewn(len * 4 / 3 + 100, char);
	    sprintf(buf2, "Proxy-Authorization: Basic ");
	    for (i = 0, j = strlen(buf2); i < len; i += 3, j += 4)
		base64_encode_atom((unsigned char *)(buf+i),
				   (len-i > 3 ? 3 : len-i), buf2+j);
	    strcpy(buf2+j, "\r\n");
	    sk_write(p->sub_socket, buf2, strlen(buf2));
	    sfree(buf);
	    sfree(buf2);
	}

static int adb_receive(Plug plug, int urgent, char *data, int len)
{
    Adb adb = (Adb) plug;
    if (adb->state == STATE_SENT_HELLO) {
        if (data[0]=='O') { // OKAY
            sk_write(adb->s,"0006shell:",10);
            adb->state = STATE_ASKED_FOR_SHELL; // wait for shell start response
        } else {
             if (data[0]=='F') {
                handle_fail(adb, data, len);
            } else {
                connection_fatal(adb->frontend, "Bad response after initial send");
            }
            return 0;
        }
    } else if (adb->state == STATE_ASKED_FOR_SHELL) {
        if (data[0]=='O') { //OKAY
            adb->state = STATE_CONNECTED; // shell started, switch to terminal mode
        } else {
            if (data[0]=='F') {
                handle_fail(adb, data, len);
            } else {
                connection_fatal(adb->frontend, "Bad response waiting for shell start");
            }
            return 0;
        }
    } else if (adb->state == STATE_WAITING_FOR_ERROR_MESSAGE) {
        do_fatal(adb, data, len);
    } else {
        c_write(adb, data, len);
    }
    return 1;
}

/*
 * Called to send data down the rlogin connection.
 */
static int rlogin_send(void *handle, char *buf, int len)
{
    Rlogin rlogin = (Rlogin) handle;

    if (rlogin->s == NULL)
	return 0;

    if (rlogin->prompt) {
        /*
         * We're still prompting for a username, and aren't talking
         * directly to the network connection yet.
         */
        int ret = get_userpass_input(rlogin->prompt,
                                     (unsigned char *)buf, len);
        if (ret >= 0) {
            rlogin_startup(rlogin, rlogin->prompt->prompts[0]->result);
            /* that nulls out rlogin->prompt, so then we'll start sending
             * data down the wire in the obvious way */
        }
    } else {
        rlogin->bufsize = sk_write(rlogin->s, buf, len);
    }

    return rlogin->bufsize;
}

int main(int argc, char *argv[])
{

	if (argc < 2) {
		usage();
	} else {
		/* Version command */
		if (argv[1][0] == 'v') {
			printf("%s\n", programVersion);
			return 1;
		}
		if (argc > 2) {
			/* Cmd Read / Write / version */
			switch (argv[2][0]) {
			case 'r':
			case 'R':
				sk_read(argc, argv);
				break;

			case 'w':
			case 'W':
				sk_write(argc, argv);
				break;
			}
		}

	}

	return 1;

}

int proxy_socks5_selectchap(Proxy_Socket p)
{
    if (p->cfg.proxy_username[0] || p->cfg.proxy_password[0]) {
	char chapbuf[514];
	int ulen;
	chapbuf[0] = '\x01'; /* Version */
	chapbuf[1] = '\x02'; /* Number of attributes sent */
	chapbuf[2] = '\x11'; /* First attribute - algorithms list */
	chapbuf[3] = '\x01'; /* Only one CHAP algorithm */
	chapbuf[4] = '\x85'; /* ...and it's HMAC-MD5, the core one */
	chapbuf[5] = '\x02'; /* Second attribute - username */

	ulen = strlen(p->cfg.proxy_username);
	if (ulen > 255) ulen = 255; if (ulen < 1) ulen = 1;

	chapbuf[6] = ulen;
	memcpy(chapbuf+7, p->cfg.proxy_username, ulen);

	sk_write(p->sub_socket, chapbuf, ulen + 7);
	p->chap_num_attributes = 0;
	p->chap_num_attributes_processed = 0;
	p->chap_current_attribute = -1;
	p->chap_current_datalen = 0;

	p->state = 8;
    } else 
	plug_closing(p->plug, "Proxy error: Server chose "
		     "CHAP authentication but we didn't offer it!",
		 PROXY_ERROR_GENERAL, 0);
    return 1;
}

static void process_subneg(Telnet telnet)
{
    unsigned char *b, *p, *q;
    int var, value, n, bsize;
    char *e, *eval, *ekey, *user;

    switch (telnet->sb_opt) {
      case TELOPT_TSPEED:
	if (telnet->sb_len == 1 && telnet->sb_buf[0] == TELQUAL_SEND) {
	    char *logbuf;
	    char *termspeed = conf_get_str(telnet->conf, CONF_termspeed);
	    b = snewn(20 + strlen(termspeed), unsigned char);
	    b[0] = IAC;
	    b[1] = SB;
	    b[2] = TELOPT_TSPEED;
	    b[3] = TELQUAL_IS;
	    strcpy((char *)(b + 4), termspeed);
	    n = 4 + strlen(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", termspeed);
	    logevent(telnet->frontend, logbuf);
	    sfree(logbuf);
	    sfree(b);
	} else

/*
 * Called to send data down the raw connection.
 */
static int raw_send(char *buf, int len)
{
    if (s == NULL)
	return 0;

    raw_bufsize = sk_write(s, buf, len);

    return raw_bufsize;
}

static int sk_proxy_write(Socket s, const char *data, int len) {
	Proxy_Socket ps = (Proxy_Socket) s;

	if (ps->state != PROXY_STATE_ACTIVE) {
		bufchain_add(&ps->pending_output_data, data, len);
		return bufchain_size(&ps->pending_output_data);
	}
	return sk_write(ps->sub_socket, data, len);
}

static int sk_proxy_write (Socket s, const void *data, int len)
{
    ProxySocket *ps = FROMFIELD(s, ProxySocket, sockvt);

    if (ps->state != PROXY_STATE_ACTIVE) {
	bufchain_add(&ps->pending_output_data, data, len);
	return bufchain_size(&ps->pending_output_data);
    }
    return sk_write(ps->sub_socket, data, len);
}

static void send_opt(Telnet telnet, int cmd, int option)
{
    unsigned char b[3];

    b[0] = IAC;
    b[1] = cmd;
    b[2] = option;
    telnet->bufsize = sk_write(telnet->s, (char *)b, 3);
    log_option(telnet, "client", cmd, option);
}

static size_t sk_proxy_write (Socket *s, const void *data, size_t len)
{
    ProxySocket *ps = container_of(s, ProxySocket, sock);

    if (ps->state != PROXY_STATE_ACTIVE) {
	bufchain_add(&ps->pending_output_data, data, len);
	return bufchain_size(&ps->pending_output_data);
    }
    return sk_write(ps->sub_socket, data, len);
}

/*
 * Called to send data down the adb connection.
 */
static int adb_send(void *handle, char *buf, int len)
{
    Adb adb = (Adb) handle;

    if (adb->s == NULL)
        return 0;

    adb->bufsize = sk_write(adb->s, buf, len);

    return adb->bufsize;
}

/*
 * Called to send data down the rlogin connection.
 */
static int rlogin_send(void *handle, char *buf, int len)
{
    Rlogin rlogin = (Rlogin) handle;

    if (rlogin->s == NULL)
	return 0;

    rlogin->bufsize = sk_write(rlogin->s, buf, len);

    return rlogin->bufsize;
}

/*
 * Call this when proxy negotiation is complete, so that this
 * socket can begin working normally.
 */
void proxy_activate(Proxy_Socket p)
{
  void *data;
  int len;
  long output_before, output_after;

  p->state = PROXY_STATE_ACTIVE;

  /* we want to ignore new receive events until we have sent
   * all of our buffered receive data.
   */
  sk_set_frozen(p->sub_socket, 1);

  /* how many bytes of output have we buffered? */
  output_before = bufchain_size(&p->pending_oob_output_data) +
                  bufchain_size(&p->pending_output_data);
  /* and keep track of how many bytes do not get sent. */
  output_after = 0;

  /* send buffered OOB writes */
  while (bufchain_size(&p->pending_oob_output_data) > 0) {
    bufchain_prefix(&p->pending_oob_output_data, &data, &len);
    output_after += sk_write_oob(p->sub_socket, data, len);
    bufchain_consume(&p->pending_oob_output_data, len);
  }

  /* send buffered normal writes */
  while (bufchain_size(&p->pending_output_data) > 0) {
    bufchain_prefix(&p->pending_output_data, &data, &len);
    output_after += sk_write(p->sub_socket, data, len);
    bufchain_consume(&p->pending_output_data, len);
  }

  /* if we managed to send any data, let the higher levels know. */
  if (output_after < output_before)
    plug_sent(p->plug, output_after);

  /* if we were asked to flush the output during
   * the proxy negotiation process, do so now.
   */
  if (p->pending_flush)
    sk_flush(p->sub_socket);

  /* if we have a pending EOF to send, send it */
  if (p->pending_eof)
    sk_write_eof(p->sub_socket);

  /* if the backend wanted the socket unfrozen, try to unfreeze.
   * our set_frozen handler will flush buffered receive data before
   * unfreezing the actual underlying socket.
   */
  if (!p->freeze)
    sk_set_frozen((Socket)p, 0);
}

/*
 * Called to send data down the raw connection.
 */
static int raw_send(void *handle, char *buf, int len)
{
    Raw raw = (Raw) handle;

    if (raw->s == NULL)
	return 0;

    raw->bufsize = sk_write(raw->s, buf, len);

    return raw->bufsize;
}

void pfd_confirm(Socket s)
{
    struct PFwdPrivate *pr;

    if (s == NULL)
	return;

    pr = (struct PFwdPrivate *) sk_get_private_ptr(s);
    pr->ready = 1;
    sk_set_frozen(s, 0);
    sk_write(s, NULL, 0);
}

/*
 * Called to set the size of the window
 */
static void rlogin_size(void)
{
    char b[12] = { '\xFF', '\xFF', 0x73, 0x73, 0, 0, 0, 0, 0, 0, 0, 0 };

    if (s == NULL)
	return;
    
    b[6] = cols >> 8;
    b[7] = cols & 0xFF;
    b[4] = rows >> 8;
    b[5] = rows & 0xFF;
    rlogin_bufsize = sk_write(s, b, 12);
    return;
}

static void rlogin_startup(Rlogin rlogin, const char *ruser)
{
    char z = 0;
    char *p;
    sk_write(rlogin->s, &z, 1);
    sk_write(rlogin->s, rlogin->cfg.localusername,
             strlen(rlogin->cfg.localusername));
    sk_write(rlogin->s, &z, 1);
    sk_write(rlogin->s, ruser,
             strlen(ruser));
    sk_write(rlogin->s, &z, 1);
    sk_write(rlogin->s, rlogin->cfg.termtype,
             strlen(rlogin->cfg.termtype));
    sk_write(rlogin->s, "/", 1);
    for (p = rlogin->cfg.termspeed; isdigit((unsigned char)*p); p++) continue;
    sk_write(rlogin->s, rlogin->cfg.termspeed, p - rlogin->cfg.termspeed);
    rlogin->bufsize = sk_write(rlogin->s, &z, 1);

    rlogin->prompt = NULL;
}

static void rlogin_startup(Rlogin rlogin, const char *ruser)
{
    char z = 0;
    char *p;

    sk_write(rlogin->s, &z, 1);
    p = conf_get_str(rlogin->conf, CONF_localusername);
    sk_write(rlogin->s, p, strlen(p));
    sk_write(rlogin->s, &z, 1);
    sk_write(rlogin->s, ruser, strlen(ruser));
    sk_write(rlogin->s, &z, 1);
    p = conf_get_str(rlogin->conf, CONF_termtype);
    sk_write(rlogin->s, p, strlen(p));
    sk_write(rlogin->s, "/", 1);
    p = conf_get_str(rlogin->conf, CONF_termspeed);
    sk_write(rlogin->s, p, strspn(p, "0123456789"));
    rlogin->bufsize = sk_write(rlogin->s, &z, 1);

    rlogin->prompt = NULL;
}

/*
 * Called to set the size of the window
 */
static void rlogin_size(void *handle, int width, int height)
{
    Rlogin rlogin = (Rlogin) handle;
    char b[12] = { '\xFF', '\xFF', 0x73, 0x73, 0, 0, 0, 0, 0, 0, 0, 0 };

    rlogin->term_width = width;
    rlogin->term_height = height;

    if (rlogin->s == NULL || !rlogin->cansize)
	return;

    b[6] = rlogin->term_width >> 8;
    b[7] = rlogin->term_width & 0xFF;
    b[4] = rlogin->term_height >> 8;
    b[5] = rlogin->term_height & 0xFF;
    rlogin->bufsize = sk_write(rlogin->s, b, 12);
    return;
}