mcs.cpp

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/*
   rdesktop: A Remote Desktop Protocol client.
   Protocol services - Multipoint Communications Service
   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"

uint16 mcs_userid;

/* Parse an ASN.1 BER header */
static BOOL
ber_parse_header(STREAM s, int tagval, unsigned int *length)
{
        int tag, len;

        if (tagval > 0xff)
        {
                in_uint16_be(s, tag);
        }
        else
        {
        in_uint8(s, tag)}

        if (tag != tagval)
        {
                error("expected tag %d, got %d\n", tagval, tag);
                return False;
        }

        in_uint8(s, len);

        if (len & 0x80)
        {
                len &= ~0x80;
                *length = 0;
                while (len--)
                        next_be(s, *length);
        }
        else
                *length = len;

        return s_check(s);
}

/* Output an ASN.1 BER header */
static void
ber_out_header(STREAM s, int tagval, int length)
{
        if (tagval > 0xff)
        {
                out_uint16_be(s, tagval);
        }
        else
        {
                out_uint8(s, tagval);
        }

        if (length >= 0x80)
        {
                out_uint8(s, 0x82);
                out_uint16_be(s, length);
        }
        else
                out_uint8(s, length);
}

/* Output an ASN.1 BER integer */
static void
ber_out_integer(STREAM s, int value)
{
        ber_out_header(s, BER_TAG_INTEGER, 2);
        out_uint16_be(s, value);
}

/* Output a DOMAIN_PARAMS structure (ASN.1 BER) */
static void
mcs_out_domain_params(STREAM s, int max_channels, int max_users, int max_tokens, int max_pdusize)
{
        ber_out_header(s, MCS_TAG_DOMAIN_PARAMS, 32);
        ber_out_integer(s, max_channels);
        ber_out_integer(s, max_users);
        ber_out_integer(s, max_tokens);
        ber_out_integer(s, 1);  /* num_priorities */
        ber_out_integer(s, 0);  /* min_throughput */
        ber_out_integer(s, 1);  /* max_height */
        ber_out_integer(s, max_pdusize);
        ber_out_integer(s, 2);  /* ver_protocol */
}

/* Parse a DOMAIN_PARAMS structure (ASN.1 BER) */
static BOOL
mcs_parse_domain_params(STREAM s)
{
        unsigned int length;

        ber_parse_header(s, MCS_TAG_DOMAIN_PARAMS, &length);
        in_uint8s(s, length);

        return s_check(s);
}

/* Send an MCS_CONNECT_INITIAL message (ASN.1 BER) */
static void
mcs_send_connect_initial(STREAM mcs_data)
{
        int datalen = mcs_data->end - mcs_data->data;
        int length = 7 + 3 * 34 + 4 + datalen;
        STREAM s;

        s = iso_init(length + 5);

        ber_out_header(s, MCS_CONNECT_INITIAL, length);
        ber_out_header(s, BER_TAG_OCTET_STRING, 0);     /* calling domain */
        ber_out_header(s, BER_TAG_OCTET_STRING, 0);     /* called domain */

        ber_out_header(s, BER_TAG_BOOLEAN, 1);
        out_uint8(s, 0xff);     /* upward flag */

        mcs_out_domain_params(s, 2, 2, 0, 0xffff);      /* target params */
        mcs_out_domain_params(s, 1, 1, 1, 0x420);       /* min params */
        mcs_out_domain_params(s, 0xffff, 0xfc17, 0xffff, 0xffff);       /* max params */

        ber_out_header(s, BER_TAG_OCTET_STRING, datalen);
        out_uint8p(s, mcs_data->data, datalen);

        s_mark_end(s);
        iso_send(s);
}

/* Expect a MCS_CONNECT_RESPONSE message (ASN.1 BER) */
static BOOL
mcs_recv_connect_response(STREAM mcs_data)
{
        uint8 result;
        unsigned int length;
        STREAM s;

        s = iso_recv();
        if (s == NULL)
                return False;

        ber_parse_header(s, MCS_CONNECT_RESPONSE, &length);

        ber_parse_header(s, BER_TAG_RESULT, &length);
        in_uint8(s, result);
        if (result != 0)
        {
                error("MCS connect: %d\n", result);
                return False;
        }

        ber_parse_header(s, BER_TAG_INTEGER, &length);
        in_uint8s(s, length);   /* connect id */
        mcs_parse_domain_params(s);

        ber_parse_header(s, BER_TAG_OCTET_STRING, &length);
        if (length > mcs_data->size)
        {
                error("MCS data length %d\n", length);
                length = mcs_data->size;
        }

        in_uint8a(s, mcs_data->data, length);
        mcs_data->p = mcs_data->data;
        mcs_data->end = mcs_data->data + length;

        return s_check_end(s);
}

/* Send an EDrq message (ASN.1 PER) */
static void
mcs_send_edrq(void)
{
        STREAM s;

        s = iso_init(5);

        out_uint8(s, (MCS_EDRQ << 2));
        out_uint16_be(s, 1);    /* height */
        out_uint16_be(s, 1);    /* interval */

        s_mark_end(s);
        iso_send(s);
}

/* Send an AUrq message (ASN.1 PER) */
static void
mcs_send_aurq(void)
{
        STREAM s;

        s = iso_init(1);

        out_uint8(s, (MCS_AURQ << 2));

        s_mark_end(s);
        iso_send(s);
}

/* Expect a AUcf message (ASN.1 PER) */
static BOOL
mcs_recv_aucf(uint16 * mcs_userid)
{
        uint8 opcode, result;
        STREAM s;

        s = iso_recv();
        if (s == NULL)
                return False;

        in_uint8(s, opcode);
        if ((opcode >> 2) != MCS_AUCF)
        {
                error("expected AUcf, got %d\n", opcode);
                return False;
        }

        in_uint8(s, result);
        if (result != 0)
        {
                error("AUrq: %d\n", result);
                return False;
        }

        if (opcode & 2)
                in_uint16_be(s, *mcs_userid);

        return s_check_end(s);
}

/* Send a CJrq message (ASN.1 PER) */
static void
mcs_send_cjrq(uint16 chanid)
{
        STREAM s;

        s = iso_init(5);

        out_uint8(s, (MCS_CJRQ << 2));
        out_uint16_be(s, mcs_userid);
        out_uint16_be(s, chanid);

        s_mark_end(s);
        iso_send(s);
}

/* Expect a CJcf message (ASN.1 PER) */
static BOOL
mcs_recv_cjcf(void)
{
        uint8 opcode, result;
        STREAM s;

        s = iso_recv();
        if (s == NULL)
                return False;

        in_uint8(s, opcode);
        if ((opcode >> 2) != MCS_CJCF)
        {
                error("expected CJcf, got %d\n", opcode);
                return False;
        }

        in_uint8(s, result);
        if (result != 0)
        {
                error("CJrq: %d\n", result);
                return False;
        }

        in_uint8s(s, 4);        /* mcs_userid, req_chanid */
        if (opcode & 2)
                in_uint8s(s, 2);        /* join_chanid */

        return s_check_end(s);
}

/* Initialise an MCS transport data packet */
STREAM
mcs_init(int length)
{
        STREAM s;

        s = iso_init(length + 8);
        s_push_layer(s, mcs_hdr, 8);

        return s;
}

/* Send an MCS transport data packet */
void
mcs_send(STREAM s)
{
        uint16 length;

        s_pop_layer(s, mcs_hdr);
        length = s->end - s->p - 8;
        length |= 0x8000;

        out_uint8(s, (MCS_SDRQ << 2));
        out_uint16_be(s, mcs_userid);
        out_uint16_be(s, MCS_GLOBAL_CHANNEL);
        out_uint8(s, 0x70);     /* flags */
        out_uint16_be(s, length);

        iso_send(s);
}

/* Receive an MCS transport data packet */
STREAM
mcs_recv(void)
{
        uint8 opcode, appid, length;
        STREAM s;

        s = iso_recv();
        if (s == NULL)
                return NULL;

        in_uint8(s, opcode);
        appid = opcode >> 2;
        if (appid != MCS_SDIN)
        {
                if (appid != MCS_DPUM)
                {
                        error("expected data, got %d\n", opcode);
                }
                return NULL;
        }

        in_uint8s(s, 5);        /* userid, chanid, flags */
        in_uint8(s, length);
        if (length & 0x80)
                in_uint8s(s, 1);        /* second byte of length */

        return s;
}

/* Establish a connection up to the MCS layer */
BOOL
mcs_connect(char *server, STREAM mcs_data)
{
        if (!iso_connect(server))
        {
                return False;
        }

        mcs_send_connect_initial(mcs_data);
        if (!mcs_recv_connect_response(mcs_data))
                goto error;

        mcs_send_edrq();

        mcs_send_aurq();
        if (!mcs_recv_aucf(&mcs_userid))
                goto error;

        mcs_send_cjrq(mcs_userid + 1001);
        if (!mcs_recv_cjcf())
                goto error;

        mcs_send_cjrq(MCS_GLOBAL_CHANNEL);
        if (!mcs_recv_cjcf())
                goto error;

        return True;

      error:
        iso_disconnect();
        return False;
}

/* Disconnect from the MCS layer */
void
mcs_disconnect(void)
{
        iso_disconnect();
}

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