guacamole-spice-protocol/src/protocols/rdp/client.c

/*
 * Copyright (C) 2013 Glyptodon LLC
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

#define _XOPEN_SOURCE 500

#include "config.h"

#include "client.h"
#include "guac_handlers.h"
#include "guac_pointer_cursor.h"
#include "rdp_bitmap.h"
#include "rdp_gdi.h"
#include "rdp_glyph.h"
#include "rdp_keymap.h"
#include "rdp_pointer.h"

#include <errno.h>
#include <pthread.h>
#include <stdlib.h>
#include <string.h>
#include <sys/select.h>

#include <freerdp/cache/bitmap.h>
#include <freerdp/cache/brush.h>
#include <freerdp/cache/glyph.h>
#include <freerdp/cache/offscreen.h>
#include <freerdp/cache/palette.h>
#include <freerdp/cache/pointer.h>
#include <freerdp/channels/channels.h>
#include <freerdp/constants.h>
#include <freerdp/freerdp.h>
#include <freerdp/input.h>
#include <guacamole/audio.h>
#include <guacamole/client.h>
#include <guacamole/error.h>
#include <guacamole/protocol.h>
#include <guacamole/socket.h>

#ifdef ENABLE_WINPR
#include <winpr/wtypes.h>
#else
#include "compat/winpr-wtypes.h"
#endif

#ifdef HAVE_FREERDP_ADDIN_H
#include <freerdp/addin.h>
#endif

#ifdef HAVE_FREERDP_CLIENT_CHANNELS_H
#include <freerdp/client/channels.h>
#endif

/* Client plugin arguments */
const char* GUAC_CLIENT_ARGS[] = {
    "hostname",
    "port",
    "domain",
    "username",
    "password",
    "width",
    "height",
    "initial-program",
    "color-depth",
    "disable-audio",
    "enable-printing",
    "enable-drive",
    "drive-path",
    "console",
    "console-audio",
    "server-layout",
    "security",
    "ignore-cert",
    "disable-auth",
    "remote-app-name",
    "remote-app-command",
    NULL
};

enum RDP_ARGS_IDX {

    IDX_HOSTNAME,
    IDX_PORT,
    IDX_DOMAIN,
    IDX_USERNAME,
    IDX_PASSWORD,
    IDX_WIDTH,
    IDX_HEIGHT,
    IDX_INITIAL_PROGRAM,
    IDX_COLOR_DEPTH,
    IDX_DISABLE_AUDIO,
    IDX_ENABLE_PRINTING,
    IDX_ENABLE_DRIVE,
    IDX_DRIVE_PATH,
    IDX_CONSOLE,
    IDX_CONSOLE_AUDIO,
    IDX_SERVER_LAYOUT,
    IDX_SECURITY,
    IDX_IGNORE_CERT,
    IDX_DISABLE_AUTH,
    IDX_REMOTE_APP_NAME,
    IDX_REMOTE_APP_COMMAND,
    RDP_ARGS_COUNT
};

int __guac_receive_channel_data(freerdp* rdp_inst, int channelId, UINT8* data, int size, int flags, int total_size) {
    return freerdp_channels_data(rdp_inst, channelId, data, size, flags, total_size);
}

BOOL rdp_freerdp_pre_connect(freerdp* instance) {

    rdpContext* context = instance->context;
    guac_client* client = ((rdp_freerdp_context*) context)->client;
    rdpChannels* channels = context->channels;
    rdpBitmap* bitmap;
    rdpGlyph* glyph;
    rdpPointer* pointer;
    rdpPrimaryUpdate* primary;
    CLRCONV* clrconv;

    rdp_guac_client_data* guac_client_data =
        (rdp_guac_client_data*) client->data;

#ifdef HAVE_FREERDP_REGISTER_ADDIN_PROVIDER
    /* Init FreeRDP add-in provider */
    freerdp_register_addin_provider(freerdp_channels_load_static_addin_entry, 0);
#endif

    /* Load clipboard plugin */
    if (freerdp_channels_load_plugin(channels, instance->settings,
                "cliprdr", NULL))
        guac_client_log_error(client, "Failed to load cliprdr plugin.");

    /* If audio enabled, choose an encoder */
    if (guac_client_data->settings.audio_enabled) {

        guac_client_data->audio = guac_audio_stream_alloc(client, NULL);

        /* If an encoding is available, load the sound plugin */
        if (guac_client_data->audio != NULL) {

            /* Load sound plugin */
            if (freerdp_channels_load_plugin(channels, instance->settings,
                        "guacsnd", guac_client_data->audio))
                guac_client_log_error(client,
                        "Failed to load guacsnd plugin.");

        }
        else
            guac_client_log_info(client,
                    "No available audio encoding. Sound disabled.");

    } /* end if audio enabled */

    /* Load filesystem if drive enabled */
    if (guac_client_data->settings.drive_enabled) {
        guac_client_data->filesystem =
            guac_rdp_fs_alloc(guac_client_data->settings.drive_path);
    }

    /* If RDPDR required, load it */
    if (guac_client_data->settings.printing_enabled
        || guac_client_data->settings.drive_enabled) {

        /* Load RDPDR plugin */
        if (freerdp_channels_load_plugin(channels, instance->settings,
                    "guacdr", client))
            guac_client_log_error(client,
                    "Failed to load guacdr plugin.");

    }

    /* Load RAIL plugin if RemoteApp in use */
    if (guac_client_data->settings.remote_app_name != NULL
        || guac_client_data->settings.remote_app_command != NULL) {

#ifdef LEGACY_FREERDP
        RDP_PLUGIN_DATA* plugin_data = malloc(sizeof(RDP_PLUGIN_DATA) * 2);

        plugin_data[0].size = sizeof(RDP_PLUGIN_DATA);
        plugin_data[0].data[0] = guac_client_data->settings.remote_app_name;
        plugin_data[0].data[1] = guac_client_data->settings.remote_app_command; 
        plugin_data[0].data[2] = NULL;
        plugin_data[0].data[3] = NULL;

        plugin_data[1].size = 0;

        /* Attempt to load rail */
        if (freerdp_channels_load_plugin(channels, instance->settings,
                    "rail", plugin_data))
            guac_client_log_error(client, "Failed to load rail plugin.");
#else
        /* Attempt to load rail */
        if (freerdp_channels_load_plugin(channels, instance->settings,
                    "rail", instance->settings))
            guac_client_log_error(client, "Failed to load rail plugin.");
#endif

    }

    /* Init color conversion structure */
    clrconv = calloc(1, sizeof(CLRCONV));
    clrconv->alpha = 1;
    clrconv->invert = 0;
    clrconv->rgb555 = 0;
    clrconv->palette = calloc(1, sizeof(rdpPalette));
    ((rdp_freerdp_context*) context)->clrconv = clrconv;

    /* Init FreeRDP cache */
    instance->context->cache = cache_new(instance->settings);

    /* Set up bitmap handling */
    bitmap = calloc(1, sizeof(rdpBitmap));
    bitmap->size = sizeof(guac_rdp_bitmap);
    bitmap->New = guac_rdp_bitmap_new;
    bitmap->Free = guac_rdp_bitmap_free;
    bitmap->Paint = guac_rdp_bitmap_paint;
    bitmap->Decompress = guac_rdp_bitmap_decompress;
    bitmap->SetSurface = guac_rdp_bitmap_setsurface;
    graphics_register_bitmap(context->graphics, bitmap);
    free(bitmap);

    /* Set up glyph handling */
    glyph = calloc(1, sizeof(rdpGlyph));
    glyph->size = sizeof(guac_rdp_glyph);
    glyph->New = guac_rdp_glyph_new;
    glyph->Free = guac_rdp_glyph_free;
    glyph->Draw = guac_rdp_glyph_draw;
    glyph->BeginDraw = guac_rdp_glyph_begindraw;
    glyph->EndDraw = guac_rdp_glyph_enddraw;
    graphics_register_glyph(context->graphics, glyph);
    free(glyph);

    /* Set up pointer handling */
    pointer = calloc(1, sizeof(rdpPointer));
    pointer->size = sizeof(guac_rdp_pointer);
    pointer->New = guac_rdp_pointer_new;
    pointer->Free = guac_rdp_pointer_free;
    pointer->Set = guac_rdp_pointer_set;
#ifdef HAVE_RDPPOINTER_SETNULL
    pointer->SetNull = guac_rdp_pointer_set_null;
#endif
#ifdef HAVE_RDPPOINTER_SETDEFAULT
    pointer->SetDefault = guac_rdp_pointer_set_default;
#endif
    graphics_register_pointer(context->graphics, pointer);
    free(pointer);

    /* Set up GDI */
    instance->update->EndPaint = guac_rdp_gdi_end_paint;
    instance->update->Palette = guac_rdp_gdi_palette_update;
    instance->update->SetBounds = guac_rdp_gdi_set_bounds;

    primary = instance->update->primary;
    primary->DstBlt = guac_rdp_gdi_dstblt;
    primary->PatBlt = guac_rdp_gdi_patblt;
    primary->ScrBlt = guac_rdp_gdi_scrblt;
    primary->MemBlt = guac_rdp_gdi_memblt;
    primary->OpaqueRect = guac_rdp_gdi_opaquerect;

    pointer_cache_register_callbacks(instance->update);
    glyph_cache_register_callbacks(instance->update);
    brush_cache_register_callbacks(instance->update);
    bitmap_cache_register_callbacks(instance->update);
    offscreen_cache_register_callbacks(instance->update);
    palette_cache_register_callbacks(instance->update);

    /* Init channels (pre-connect) */
    if (freerdp_channels_pre_connect(channels, instance)) {
        guac_protocol_send_error(client->socket,
                "Error initializing RDP client channel manager",
                GUAC_PROTOCOL_STATUS_INTERNAL_ERROR);
        guac_socket_flush(client->socket);
        return FALSE;
    }

    return TRUE;

}

BOOL rdp_freerdp_post_connect(freerdp* instance) {

    rdpContext* context = instance->context;
    guac_client* client = ((rdp_freerdp_context*) context)->client;
    rdpChannels* channels = instance->context->channels;

    /* Init channels (post-connect) */
    if (freerdp_channels_post_connect(channels, instance)) {
        guac_protocol_send_error(client->socket,
                "Error initializing RDP client channel manager",
                GUAC_PROTOCOL_STATUS_INTERNAL_ERROR);
        guac_socket_flush(client->socket);
        return FALSE;
    }

    /* Client handlers */
    client->free_handler = rdp_guac_client_free_handler;
    client->handle_messages = rdp_guac_client_handle_messages;
    client->mouse_handler = rdp_guac_client_mouse_handler;
    client->key_handler = rdp_guac_client_key_handler;
    client->clipboard_handler = rdp_guac_client_clipboard_handler;

    /* File transfer handlers */
    client->file_handler = rdp_guac_client_file_handler;
    client->blob_handler = rdp_guac_client_blob_handler;
    client->end_handler = rdp_guac_client_end_handler;
    client->ack_handler = rdp_guac_client_ack_handler;

    return TRUE;

}

BOOL rdp_freerdp_authenticate(freerdp* instance, char** username,
        char** password, char** domain) {

    rdpContext* context = instance->context;
    guac_client* client = ((rdp_freerdp_context*) context)->client;

    /* Warn if connection is likely to fail due to lack of credentials */
    guac_client_log_info(client,
            "Authentication requested but username or password not given");
    return TRUE;

}

BOOL rdp_freerdp_verify_certificate(freerdp* instance, char* subject,
        char* issuer, char* fingerprint) {

    rdpContext* context = instance->context;
    guac_client* client = ((rdp_freerdp_context*) context)->client;
    rdp_guac_client_data* guac_client_data =
        (rdp_guac_client_data*) client->data;

    /* Bypass validation if ignore_certificate given */
    if (guac_client_data->settings.ignore_certificate) {
        guac_client_log_info(client, "Certificate validation bypassed");
        return TRUE;
    }

    guac_client_log_info(client, "Certificate validation failed");
    return FALSE;

}

void rdp_freerdp_context_new(freerdp* instance, rdpContext* context) {
    context->channels = freerdp_channels_new();
}

void rdp_freerdp_context_free(freerdp* instance, rdpContext* context) {
    /* EMPTY */
}

void __guac_rdp_client_load_keymap(guac_client* client,
        const guac_rdp_keymap* keymap) {

    rdp_guac_client_data* guac_client_data =
        (rdp_guac_client_data*) client->data;

    /* Get mapping */
    const guac_rdp_keysym_desc* mapping = keymap->mapping;

    /* If parent exists, load parent first */
    if (keymap->parent != NULL)
        __guac_rdp_client_load_keymap(client, keymap->parent);

    /* Log load */
    guac_client_log_info(client, "Loading keymap \"%s\"", keymap->name);

    /* Load mapping into keymap */
    while (mapping->keysym != 0) {

        /* Copy mapping */
        GUAC_RDP_KEYSYM_LOOKUP(guac_client_data->keymap, mapping->keysym) =
            *mapping;

        /* Next keysym */
        mapping++;

    }

}

int guac_client_init(guac_client* client, int argc, char** argv) {

    rdp_guac_client_data* guac_client_data;
    guac_rdp_settings* settings;

    freerdp* rdp_inst;

    /* Validate number of arguments received */
    if (argc != RDP_ARGS_COUNT) {

        guac_protocol_send_error(client->socket,
                "Wrong argument count received.",
                GUAC_PROTOCOL_STATUS_INVALID_PARAMETER);
        guac_socket_flush(client->socket);

        guac_error = GUAC_STATUS_BAD_ARGUMENT;
        guac_error_message = "Wrong argument count received";

        return 1;
    }

    /* Allocate client data */
    guac_client_data = malloc(sizeof(rdp_guac_client_data));

    /* Init random number generator */
    srandom(time(NULL));

    /* Init client */
    freerdp_channels_global_init();
    rdp_inst = freerdp_new();
    rdp_inst->PreConnect = rdp_freerdp_pre_connect;
    rdp_inst->PostConnect = rdp_freerdp_post_connect;
    rdp_inst->Authenticate = rdp_freerdp_authenticate;
    rdp_inst->VerifyCertificate = rdp_freerdp_verify_certificate;
    rdp_inst->ReceiveChannelData = __guac_receive_channel_data;

    /* Allocate FreeRDP context */
#ifdef LEGACY_FREERDP
    rdp_inst->context_size = sizeof(rdp_freerdp_context);
#else
    rdp_inst->ContextSize = sizeof(rdp_freerdp_context);
#endif
    rdp_inst->ContextNew  = (pContextNew) rdp_freerdp_context_new;
    rdp_inst->ContextFree = (pContextFree) rdp_freerdp_context_free;
    freerdp_context_new(rdp_inst);

    /* Set settings */
    settings = &(guac_client_data->settings);

    /* Console */
    settings->console         = (strcmp(argv[IDX_CONSOLE], "true") == 0);
    settings->console_audio   = (strcmp(argv[IDX_CONSOLE_AUDIO], "true") == 0);

    /* Certificate and auth */
    settings->ignore_certificate = (strcmp(argv[IDX_IGNORE_CERT], "true") == 0);
    settings->disable_authentication = (strcmp(argv[IDX_DISABLE_AUTH], "true") == 0);

    /* NLA security */
    if (strcmp(argv[IDX_SECURITY], "nla") == 0) {
        guac_client_log_info(client, "Security mode: NLA");
        settings->security_mode = GUAC_SECURITY_NLA;
    }

    /* TLS security */
    else if (strcmp(argv[IDX_SECURITY], "tls") == 0) {
        guac_client_log_info(client, "Security mode: TLS");
        settings->security_mode = GUAC_SECURITY_TLS;
    }

    /* RDP security */
    else if (strcmp(argv[IDX_SECURITY], "rdp") == 0) {
        guac_client_log_info(client, "Security mode: RDP");
        settings->security_mode = GUAC_SECURITY_RDP;
    }

    /* ANY security (allow server to choose) */
    else if (strcmp(argv[IDX_SECURITY], "any") == 0) {
        guac_client_log_info(client, "Security mode: ANY");
        settings->security_mode = GUAC_SECURITY_ANY;
    }

    /* If nothing given, default to RDP */
    else {
        guac_client_log_info(client, "No security mode specified. Defaulting to RDP.");
        settings->security_mode = GUAC_SECURITY_RDP;
    }

    /* Set hostname */
    settings->hostname = strdup(argv[IDX_HOSTNAME]);

    /* If port specified, use it */
    settings->port = RDP_DEFAULT_PORT;
    if (argv[IDX_PORT][0] != '\0')
        settings->port = atoi(argv[IDX_PORT]);

    /* Use optimal width unless overridden */
    settings->width = client->info.optimal_width * 96 / client->info.optimal_resolution;
    if (argv[IDX_WIDTH][0] != '\0')
        settings->width = atoi(argv[IDX_WIDTH]);

    /* Use default width if given width is invalid. */
    if (settings->width <= 0) {
        settings->width = RDP_DEFAULT_WIDTH;
        guac_client_log_error(client,
                "Invalid width: \"%s\". Using default of %i.",
                argv[IDX_WIDTH], settings->width);
    }

    /* Round width down to nearest multiple of 4 */
    settings->width = settings->width & ~0x3;

    /* Use optimal height unless overridden */
    settings->height = client->info.optimal_height * 96 / client->info.optimal_resolution;
    if (argv[IDX_HEIGHT][0] != '\0')
        settings->height = atoi(argv[IDX_HEIGHT]);

    /* Use default height if given height is invalid. */
    if (settings->height <= 0) {
        settings->height = RDP_DEFAULT_HEIGHT;
        guac_client_log_error(client,
                "Invalid height: \"%s\". Using default of %i.",
                argv[IDX_WIDTH], settings->height);
    }

    /* Domain */
    settings->domain = NULL;
    if (argv[IDX_DOMAIN][0] != '\0')
        settings->domain = strdup(argv[IDX_DOMAIN]);

    /* Username */
    settings->username = NULL;
    if (argv[IDX_USERNAME][0] != '\0')
        settings->username = strdup(argv[IDX_USERNAME]);

    /* Password */
    settings->password = NULL;
    if (argv[IDX_PASSWORD][0] != '\0')
        settings->password = strdup(argv[IDX_PASSWORD]);

    /* Initial program */
    settings->initial_program = NULL;
    if (argv[IDX_INITIAL_PROGRAM][0] != '\0')
        settings->initial_program = strdup(argv[IDX_INITIAL_PROGRAM]);

    /* RemoteApp name */
    settings->remote_app_name = NULL;
    if (argv[IDX_REMOTE_APP_NAME][0] != '\0')
        settings->remote_app_name = strdup(argv[IDX_REMOTE_APP_NAME]);

    /* RemoteApp command */
    settings->remote_app_command = NULL;
    if (argv[IDX_REMOTE_APP_COMMAND][0] != '\0')
        settings->remote_app_command = strdup(argv[IDX_REMOTE_APP_COMMAND]);

    /* Session color depth */
    settings->color_depth = RDP_DEFAULT_DEPTH;
    if (argv[IDX_COLOR_DEPTH][0] != '\0')
        settings->color_depth = atoi(argv[IDX_COLOR_DEPTH]);

    /* Use default depth if given depth is invalid. */
    if (settings->color_depth == 0) {
        settings->color_depth = RDP_DEFAULT_DEPTH;
        guac_client_log_error(client,
                "Invalid color-depth: \"%s\". Using default of %i.",
                argv[IDX_WIDTH], settings->color_depth);
    }

    /* Audio enable/disable */
    guac_client_data->settings.audio_enabled =
        (strcmp(argv[IDX_DISABLE_AUDIO], "true") != 0);

    /* Printing enable/disable */
    guac_client_data->settings.printing_enabled =
        (strcmp(argv[IDX_ENABLE_PRINTING], "true") == 0);

    /* Drive enable/disable */
    guac_client_data->settings.drive_enabled =
        (strcmp(argv[IDX_ENABLE_DRIVE], "true") == 0);

    guac_client_data->settings.drive_path = strdup(argv[IDX_DRIVE_PATH]);

    /* Store client data */
    guac_client_data->rdp_inst = rdp_inst;
    guac_client_data->bounded = FALSE;
    guac_client_data->mouse_button_mask = 0;
    guac_client_data->current_surface = GUAC_DEFAULT_LAYER;
    guac_client_data->clipboard = NULL;
    guac_client_data->audio = NULL;
    guac_client_data->filesystem = NULL;

    /* Main socket needs to be threadsafe */
    guac_socket_require_threadsafe(client->socket);

    /* Recursive attribute for locks */
    pthread_mutexattr_init(&(guac_client_data->attributes));
    pthread_mutexattr_settype(&(guac_client_data->attributes),
            PTHREAD_MUTEX_RECURSIVE);

    /* Init RDP lock */
    pthread_mutex_init(&(guac_client_data->rdp_lock),
           &(guac_client_data->attributes));

    /* Clear keysym state mapping and keymap */
    memset(guac_client_data->keysym_state, 0,
            sizeof(guac_rdp_keysym_state_map));

    memset(guac_client_data->keymap, 0,
            sizeof(guac_rdp_static_keymap));

    client->data = guac_client_data;
    ((rdp_freerdp_context*) rdp_inst->context)->client = client;

    /* Pick keymap based on argument */
    settings->server_layout = NULL;
    if (argv[IDX_SERVER_LAYOUT][0] != '\0')
        settings->server_layout =
            guac_rdp_keymap_find(argv[IDX_SERVER_LAYOUT]);

    /* If no keymap requested, use default */
    if (settings->server_layout == NULL)
        settings->server_layout = guac_rdp_keymap_find(GUAC_DEFAULT_KEYMAP);

    /* Load keymap into client */
    __guac_rdp_client_load_keymap(client, settings->server_layout);

    /* Push desired settings to FreeRDP */
    guac_rdp_push_settings(settings, rdp_inst);

    /* Connect to RDP server */
    if (!freerdp_connect(rdp_inst)) {

        guac_protocol_send_error(client->socket,
                "Error connecting to RDP server",
                GUAC_PROTOCOL_STATUS_INTERNAL_ERROR);
        guac_socket_flush(client->socket);

        guac_error = GUAC_STATUS_BAD_STATE;
        guac_error_message = "Error connecting to RDP server";

        return 1;
    }

    /* Pull actual settings back from FreeRDP */
    guac_rdp_pull_settings(rdp_inst, settings);

    /* Send connection name */
    guac_protocol_send_name(client->socket, settings->hostname);

    /* Send size */
    guac_protocol_send_size(client->socket, GUAC_DEFAULT_LAYER,
            settings->width, settings->height);

    /* Create glyph surfaces */
    guac_client_data->opaque_glyph_surface = cairo_image_surface_create(
            CAIRO_FORMAT_RGB24, settings->width, settings->height);

    guac_client_data->trans_glyph_surface = cairo_image_surface_create(
            CAIRO_FORMAT_ARGB32, settings->width, settings->height);

    /* Set default pointer */
    guac_common_set_pointer_cursor(client);

    /* Success */
    return 0;

}

int guac_rdp_clip_rect(rdp_guac_client_data* data, int* x, int* y, int* w, int* h) {

    if (data->bounded) {

        /* Get rect coordinates */
        int clipped_left   = *x;
        int clipped_top    = *y;
        int clipped_right  = clipped_left + *w - 1;
        int clipped_bottom = clipped_top  + *h - 1;

        /* Clip left */
        if      (clipped_left < data->bounds_left)  clipped_left = data->bounds_left;
        else if (clipped_left > data->bounds_right) return 1;

        /* Clip right */
        if      (clipped_right < data->bounds_left)  return 1;
        else if (clipped_right > data->bounds_right) clipped_right = data->bounds_right;

        /* Clip top */
        if      (clipped_top < data->bounds_top)    clipped_top = data->bounds_top;
        else if (clipped_top > data->bounds_bottom) return 1;

        /* Clip bottom */
        if      (clipped_bottom < data->bounds_top)    return 1;
        else if (clipped_bottom > data->bounds_bottom) clipped_bottom = data->bounds_bottom;

        /* Store new rect dimensions */
        *x = clipped_left;
        *y = clipped_top;
        *w = clipped_right  - clipped_left + 1;
        *h = clipped_bottom - clipped_top  + 1;

    }

    return 0;

}