src/protocols/rdp/channels/disp.c

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

#include "channels/disp.h"
#include "plugins/channels.h"
#include "rdp.h"
#include "settings.h"

#include <freerdp/client/disp.h>
#include <freerdp/freerdp.h>
#include <freerdp/event.h>
#include <guacamole/client.h>
#include <guacamole/timestamp.h>

#include <stdlib.h>
#include <string.h>

guac_rdp_disp* guac_rdp_disp_alloc() {

    guac_rdp_disp* disp = malloc(sizeof(guac_rdp_disp));

    /* Not yet connected */
    disp->disp = NULL;

    /* No requests have been made */
    disp->last_request = guac_timestamp_current();
    disp->requested_width  = 0;
    disp->requested_height = 0;
    disp->reconnect_needed = 0;

    return disp;

}

void guac_rdp_disp_free(guac_rdp_disp* disp) {
    free(disp);
}

/**
 * Callback which associates handlers specific to Guacamole with the
 * DispClientContext instance allocated by FreeRDP to deal with received
 * Display Update (client-initiated dynamic display resizing) messages.
 *
 * This function is called whenever a channel connects via the PubSub event
 * system within FreeRDP, but only has any effect if the connected channel is
 * the Display Update channel. This specific callback is registered with the
 * PubSub system of the relevant rdpContext when guac_rdp_disp_load_plugin() is
 * called.
 *
 * @param context
 *     The rdpContext associated with the active RDP session.
 *
 * @param e
 *     Event-specific arguments, mainly the name of the channel, and a
 *     reference to the associated plugin loaded for that channel by FreeRDP.
 */
static void guac_rdp_disp_channel_connected(rdpContext* context,
        ChannelConnectedEventArgs* e) {

    guac_client* client = ((rdp_freerdp_context*) context)->client;
    guac_rdp_client* rdp_client = (guac_rdp_client*) client->data;
    guac_rdp_disp* guac_disp = rdp_client->disp;

    /* Ignore connection event if it's not for the Display Update channel */
    if (strcmp(e->name, DISP_DVC_CHANNEL_NAME) != 0)
        return;

    /* Init module with current display size */
    guac_rdp_disp_set_size(guac_disp, rdp_client->settings,
            context->instance, guac_rdp_get_width(context->instance),
            guac_rdp_get_height(context->instance));

    /* Store reference to the display update plugin once it's connected */
    DispClientContext* disp = (DispClientContext*) e->pInterface;
    guac_disp->disp = disp;

    guac_client_log(client, GUAC_LOG_DEBUG, "Display update channel "
            "will be used for display size changes.");

}

void guac_rdp_disp_load_plugin(rdpContext* context) {

    /* Subscribe to and handle channel connected events */
    PubSub_SubscribeChannelConnected(context->pubSub,
        (pChannelConnectedEventHandler) guac_rdp_disp_channel_connected);

    /* Add "disp" channel */
    guac_freerdp_dynamic_channel_collection_add(context->settings, "disp", NULL);

}

/**
 * Fits a given dimension within the allowed bounds for Display Update
 * messages, adjusting the other dimension such that aspect ratio is
 * maintained.
 *
 * @param a The dimension to fit within allowed bounds.
 *
 * @param b
 *     The other dimension to adjust if and only if necessary to preserve
 *     aspect ratio.
 */
static void guac_rdp_disp_fit(int* a, int* b) {

    int a_value = *a;
    int b_value = *b;

    /* Ensure first dimension is within allowed range */
    if (a_value < GUAC_RDP_DISP_MIN_SIZE) {

        /* Adjust other dimension to maintain aspect ratio */
        int adjusted_b = b_value * GUAC_RDP_DISP_MIN_SIZE / a_value;
        if (adjusted_b > GUAC_RDP_DISP_MAX_SIZE)
            adjusted_b = GUAC_RDP_DISP_MAX_SIZE;

        *a = GUAC_RDP_DISP_MIN_SIZE;
        *b = adjusted_b;

    }
    else if (a_value > GUAC_RDP_DISP_MAX_SIZE) {

        /* Adjust other dimension to maintain aspect ratio */
        int adjusted_b = b_value * GUAC_RDP_DISP_MAX_SIZE / a_value;
        if (adjusted_b < GUAC_RDP_DISP_MIN_SIZE)
            adjusted_b = GUAC_RDP_DISP_MIN_SIZE;

        *a = GUAC_RDP_DISP_MAX_SIZE;
        *b = adjusted_b;

    }

}

void guac_rdp_disp_set_size(guac_rdp_disp* disp, guac_rdp_settings* settings,
        freerdp* rdp_inst, int width, int height) {

    /* Fit width within bounds, adjusting height to maintain aspect ratio */
    guac_rdp_disp_fit(&width, &height);

    /* Fit height within bounds, adjusting width to maintain aspect ratio */
    guac_rdp_disp_fit(&height, &width);

    /* Width must be even */
    if (width % 2 == 1)
        width -= 1;

    /* Store deferred size */
    disp->requested_width = width;
    disp->requested_height = height;

    /* Send display update notification if possible */
    guac_rdp_disp_update_size(disp, settings, rdp_inst);

}

void guac_rdp_disp_update_size(guac_rdp_disp* disp,
        guac_rdp_settings* settings, freerdp* rdp_inst) {

    int width = disp->requested_width;
    int height = disp->requested_height;

    /* Do not update size if no requests have been received */
    if (width == 0 || height == 0)
        return;

    guac_timestamp now = guac_timestamp_current();

    /* Limit display update frequency */
    if (now - disp->last_request <= GUAC_RDP_DISP_UPDATE_INTERVAL)
        return;

    /* Do NOT send requests unless the size will change */
    if (rdp_inst != NULL
            && width == guac_rdp_get_width(rdp_inst)
            && height == guac_rdp_get_height(rdp_inst))
        return;

    disp->last_request = now;

    if (settings->resize_method == GUAC_RESIZE_RECONNECT) {

        /* Update settings with new dimensions */
        settings->width = width;
        settings->height = height;

        /* Signal reconnect */
        disp->reconnect_needed = 1;

    }

    else if (settings->resize_method == GUAC_RESIZE_DISPLAY_UPDATE) {
        DISPLAY_CONTROL_MONITOR_LAYOUT monitors[1] = {{
            .Flags  = 0x1, /* DISPLAYCONTROL_MONITOR_PRIMARY */
            .Left = 0,
            .Top = 0,
            .Width  = width,
            .Height = height,
            .PhysicalWidth = 0,
            .PhysicalHeight = 0,
            .Orientation = 0,
            .DesktopScaleFactor = 0,
            .DeviceScaleFactor = 0
        }};

        /* Send display update notification if display channel is connected */
        if (disp->disp != NULL)
            disp->disp->SendMonitorLayout(disp->disp, 1, monitors);
    }

}

int guac_rdp_disp_reconnect_needed(guac_rdp_disp* disp) {
    return disp->reconnect_needed;
}

void guac_rdp_disp_reconnect_complete(guac_rdp_disp* disp) {
    disp->reconnect_needed = 0;
    disp->last_request = guac_timestamp_current();
}