iso.cpp

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/*
   rdesktop: A Remote Desktop Protocol client.
   Protocol services - ISO layer
   Copyright (C) Matthew Chapman 1999-2002
   
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.
   
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
   
   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

#include "rdesktop.h"

/* Send a self-contained ISO PDU */
static void
iso_send_msg(uint8 code)
{
        STREAM s;

        s = tcp_init(11);

        out_uint8(s, 3);        /* version */
        out_uint8(s, 0);        /* reserved */
        out_uint16_be(s, 11);   /* length */

        out_uint8(s, 6);        /* hdrlen */
        out_uint8(s, code);
        out_uint16(s, 0);       /* dst_ref */
        out_uint16(s, 0);       /* src_ref */
        out_uint8(s, 0);        /* class */

        s_mark_end(s);
        tcp_send(s);
}

/* Receive a message on the ISO layer, return code */
static STREAM
iso_recv_msg(uint8 * code)
{
        STREAM s;
        uint16 length;
        uint8 version;

        s = tcp_recv(4);
        if (s == NULL)
        {
                return NULL;
        }

        in_uint8(s, version);
        if (version != 3)
        {
                error("TPKT v%d\n", version);
                return NULL;
        }

        in_uint8s(s, 1);        /* pad */
        in_uint16_be(s, length);

        s = tcp_recv(length - 4);
        if (s == NULL)
                return NULL;

        in_uint8s(s, 1);        /* hdrlen */
        in_uint8(s, *code);

        if (*code == ISO_PDU_DT)
        {
                in_uint8s(s, 1);        /* eot */
                return s;
        }

        in_uint8s(s, 5);        /* dst_ref, src_ref, class */
        return s;
}

/* Initialise ISO transport data packet */
STREAM
iso_init(int length)
{
        STREAM s;

        s = tcp_init(length + 7);
        s_push_layer(s, iso_hdr, 7);

        return s;
}

/* Send an ISO data PDU */
void
iso_send(STREAM s)
{
        uint16 length;

        s_pop_layer(s, iso_hdr);
        length = s->end - s->p;

        out_uint8(s, 3);        /* version */
        out_uint8(s, 0);        /* reserved */
        out_uint16_be(s, length);

        out_uint8(s, 2);        /* hdrlen */
        out_uint8(s, ISO_PDU_DT);       /* code */
        out_uint8(s, 0x80);     /* eot */

        tcp_send(s);
}

/* Receive ISO transport data packet */
STREAM
iso_recv(void)
{
        STREAM s;
        uint8 code;

        s = iso_recv_msg(&code);
        if (s == NULL)
                return NULL;

        if (code != ISO_PDU_DT)
        {
                error("expected DT, got 0x%x\n", code);
                return NULL;
        }

        return s;
}

/* Establish a connection up to the ISO layer */
BOOL
iso_connect(char *server)
{
        uint8 code;

        if (!tcp_connect(server))
                return False;

        iso_send_msg(ISO_PDU_CR);

        if (iso_recv_msg(&code) == NULL)
        {
                return False;
        }

        if (code != ISO_PDU_CC)
        {
                error("expected CC, got 0x%x\n", code);
                tcp_disconnect();
                return False;
        }

        return True;
}

/* Disconnect from the ISO layer */
void
iso_disconnect(void)
{
        iso_send_msg(ISO_PDU_DR);
        tcp_disconnect();
}

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