source: vbox/trunk/src/VBox/RDP/client/channels.c@ 8794

/* -*- c-basic-offset: 8 -*-
   rdesktop: A Remote Desktop Protocol client.
   Protocol services - Virtual channels
   Copyright (C) Erik Forsberg <[email protected]> 2003
   Copyright (C) Matthew Chapman 2003-2005

   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"

#define MAX_CHANNELS                    6
#define CHANNEL_CHUNK_LENGTH            1600
#define CHANNEL_FLAG_FIRST              0x01
#define CHANNEL_FLAG_LAST               0x02
#define CHANNEL_FLAG_SHOW_PROTOCOL      0x10

extern BOOL g_use_rdp5;
extern BOOL g_encryption;

VCHANNEL g_channels[MAX_CHANNELS];
unsigned int g_num_channels;

/* FIXME: We should use the information in TAG_SRV_CHANNELS to map RDP5
   channels to MCS channels.

   The format of TAG_SRV_CHANNELS seems to be

   global_channel_no (uint16le)
   number_of_other_channels (uint16le)
   ..followed by uint16les for the other channels.
*/

VCHANNEL *
channel_register(char *name, uint32 flags, void (*callback) (STREAM))
{
        VCHANNEL *channel;

        if (!g_use_rdp5)
                return NULL;

        if (g_num_channels >= MAX_CHANNELS)
        {
                error("Channel table full, increase MAX_CHANNELS\n");
                return NULL;
        }

        channel = &g_channels[g_num_channels];
        channel->mcs_id = MCS_GLOBAL_CHANNEL + 1 + g_num_channels;
        strncpy(channel->name, name, 8);
        channel->flags = flags;
        channel->process = callback;
        g_num_channels++;
        return channel;
}

STREAM
channel_init(VCHANNEL * channel, uint32 length)
{
        STREAM s;

        s = sec_init(g_encryption ? SEC_ENCRYPT : 0, length + 8);
        s_push_layer(s, channel_hdr, 8);
        return s;
}

void
channel_send(STREAM s, VCHANNEL * channel)
{
        uint32 length, flags;
        uint32 thislength, remaining;
        uint8 *data;

        /* first fragment sent in-place */
        s_pop_layer(s, channel_hdr);
        length = s->end - s->p - 8;

        DEBUG_CHANNEL(("channel_send, length = %d\n", length));

        thislength = MIN(length, CHANNEL_CHUNK_LENGTH);
/* Note: In the original clipboard implementation, this number was
   1592, not 1600. However, I don't remember the reason and 1600 seems
   to work so.. This applies only to *this* length, not the length of
   continuation or ending packets. */
        remaining = length - thislength;
        flags = (remaining == 0) ? CHANNEL_FLAG_FIRST | CHANNEL_FLAG_LAST : CHANNEL_FLAG_FIRST;
        if (channel->flags & CHANNEL_OPTION_SHOW_PROTOCOL)
                flags |= CHANNEL_FLAG_SHOW_PROTOCOL;

        out_uint32_le(s, length);
        out_uint32_le(s, flags);
        data = s->end = s->p + thislength;
        DEBUG_CHANNEL(("Sending %d bytes with FLAG_FIRST\n", thislength));
        sec_send_to_channel(s, g_encryption ? SEC_ENCRYPT : 0, channel->mcs_id);

        /* subsequent segments copied (otherwise would have to generate headers backwards) */
        while (remaining > 0)
        {
                thislength = MIN(remaining, CHANNEL_CHUNK_LENGTH);
                remaining -= thislength;
                flags = (remaining == 0) ? CHANNEL_FLAG_LAST : 0;
                if (channel->flags & CHANNEL_OPTION_SHOW_PROTOCOL)
                        flags |= CHANNEL_FLAG_SHOW_PROTOCOL;

                DEBUG_CHANNEL(("Sending %d bytes with flags %d\n", thislength, flags));

                s = sec_init(g_encryption ? SEC_ENCRYPT : 0, thislength + 8);
                out_uint32_le(s, length);
                out_uint32_le(s, flags);
                out_uint8p(s, data, thislength);
                s_mark_end(s);
                sec_send_to_channel(s, g_encryption ? SEC_ENCRYPT : 0, channel->mcs_id);

                data += thislength;
        }
}

void
channel_process(STREAM s, uint16 mcs_channel)
{
        uint32 length, flags;
        uint32 thislength;
        VCHANNEL *channel = NULL;
        unsigned int i;
        STREAM in;

        for (i = 0; i < g_num_channels; i++)
        {
                channel = &g_channels[i];
                if (channel->mcs_id == mcs_channel)
                        break;
        }

        if (i >= g_num_channels)
                return;

        in_uint32_le(s, length);
        in_uint32_le(s, flags);
        if ((flags & CHANNEL_FLAG_FIRST) && (flags & CHANNEL_FLAG_LAST))
        {
                /* single fragment - pass straight up */
                channel->process(s);
        }
        else
        {
                /* add fragment to defragmentation buffer */
                in = &channel->in;
                if (flags & CHANNEL_FLAG_FIRST)
                {
                        if (length > in->size)
                        {
                                in->data = (uint8 *) xrealloc(in->data, length);
                                in->size = length;
                        }
                        in->p = in->data;
                }

                thislength = MIN(s->end - s->p, in->data + in->size - in->p);
                memcpy(in->p, s->p, thislength);
                in->p += thislength;

                if (flags & CHANNEL_FLAG_LAST)
                {
                        in->end = in->p;
                        in->p = in->data;
                        channel->process(in);
                }
        }
}