GUACAMOLE-1196: Add VNC protocol support for updating display size.

src/protocols/vnc/client.c

@@ -106,11 +106,16 @@ int guac_client_init(guac_client* client) {
     guac_vnc_client* vnc_client = guac_mem_zalloc(sizeof(guac_vnc_client));
     client->data = vnc_client;
 
+    vnc_client->vnc_display = guac_vnc_display_update_alloc(client);
+
 #ifdef ENABLE_VNC_TLS_LOCKING
     /* Initialize the TLS write lock */
     pthread_mutex_init(&vnc_client->tls_lock, NULL);
 #endif
 
+    /* Initialize the message lock. */
+    pthread_mutex_init(&(vnc_client->message_lock), NULL);
+
     /* Init clipboard */
     vnc_client->clipboard = guac_common_clipboard_alloc();
 
@@ -209,6 +214,11 @@ int guac_vnc_client_free_handler(guac_client* client) {
     pthread_mutex_destroy(&(vnc_client->tls_lock));
 #endif
 
+    /* Clean up the message lock. */
+    pthread_mutex_destroy(&(vnc_client->message_lock));
+
+    guac_vnc_display_update_free(vnc_client->vnc_display);
+
     /* Free generic data struct */
     guac_mem_free(client->data);
 

src/protocols/vnc/display.c

@@ -20,6 +20,7 @@
 #include "config.h"
 
 #include "client.h"
+#include "display.h"
 #include "common/iconv.h"
 #include "common/surface.h"
 #include "vnc.h"
@@ -30,6 +31,7 @@
 #include <guacamole/mem.h>
 #include <guacamole/protocol.h>
 #include <guacamole/socket.h>
+#include <guacamole/timestamp.h>
 #include <rfb/rfbclient.h>
 #include <rfb/rfbproto.h>
 
@@ -153,6 +155,88 @@ void guac_vnc_copyrect(rfbClient* client, int src_x, int src_y, int w, int h, in
 
 }
 
+guac_vnc_display* guac_vnc_display_update_alloc(guac_client* client) {
+
+    guac_vnc_display* display = guac_mem_alloc(sizeof(guac_vnc_display));
+    display->client = client;
+
+    /* No requests have been made */
+    display->last_request = guac_timestamp_current();
+    display->requested_width  = 0;
+    display->requested_height = 0;
+
+    return display;
+
+}
+
+void guac_vnc_display_update_free(guac_vnc_display* display) {
+    guac_mem_free(display);
+}
+
+/**
+ * This function does the actual work of updating the display size if adequate
+ * time has passed since the last update and the size is actually different.
+*
+ * @param display
+ *     The data structure that contains information used for determing if and
+ *     when display updates should be allowed.
+ *
+ * @param rfb_client
+ *     A pointer to the VNC (RFB) client.
+ */
+static void guac_vnc_display_update_size(guac_vnc_display* display,
+        rfbClient* rfb_client) {
+
+    int width = display->requested_width;
+    int height = display->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 - display->last_request <= GUAC_COMMON_DISPLAY_UPDATE_INTERVAL)
+        return;
+
+    /* Do NOT send requests unless the size will change */
+    if (rfb_client != NULL
+            && width == rfb_client->screen.width
+            && height == rfb_client->screen.height)
+        return;
+
+    /* Send the display size update. */
+    guac_vnc_client* vnc_client = (guac_vnc_client*) display->client->data;
+    pthread_mutex_lock(&(vnc_client->message_lock));
+    SendExtDesktopSize(rfb_client, width, height);
+    display->last_request = now;
+    pthread_mutex_unlock(&(vnc_client->message_lock));
+
+}
+
+void guac_vnc_display_set_size(guac_vnc_display* display,
+        rfbClient* rfb_client, int width, int height) {
+
+    /* Fit width within bounds, adjusting height to maintain aspect ratio */
+    guac_common_display_fit(&width, &height);
+
+    /* Fit height within bounds, adjusting width to maintain aspect ratio */
+    guac_common_display_fit(&height, &width);
+
+    /* Width must be even */
+    if (width % 2 == 1)
+        width -= 1;
+
+    /* Store deferred size */
+    display->requested_width = width;
+    display->requested_height = height;
+
+    /* Send display update notification if possible */
+    guac_vnc_display_update_size(display, rfb_client);
+
+}
+
 void guac_vnc_set_pixel_format(rfbClient* client, int color_depth) {
     client->format.trueColour = 1;
     switch(color_depth) {
@@ -205,4 +289,3 @@ rfbBool guac_vnc_malloc_framebuffer(rfbClient* rfb_client) {
     /* Use original, wrapped proc */
     return vnc_client->rfb_MallocFrameBuffer(rfb_client);
 }
-

src/protocols/vnc/display.h

@@ -26,8 +26,36 @@
 #include <rfb/rfbproto.h>
 
 /**
- * Callback invoked by libVNCServer when it receives a new binary image data.
- * the VNC server. The image itself will be stored in the designated sub-
+ * Display size update module for VNC.
+ */
+typedef struct guac_vnc_display {
+
+    /**
+     * The guac_client instance handling the relevant VNC connection.
+     */
+    guac_client* client;
+
+    /**
+     * The timestamp of the last display update request, or 0 if no request
+     * has been sent yet.
+     */
+    guac_timestamp last_request;
+
+    /**
+     * The last requested screen width, in pixels.
+     */
+    int requested_width;
+
+    /**
+     * The last requested screen height, in pixels.
+     */
+    int requested_height;
+
+} guac_vnc_display;
+
+/**
+ * Callback invoked by libVNCServer when it receives a new binary image data
+ * from the VNC server. The image itself will be stored in the designated sub-
  * rectangle of client->framebuffer.
  *
  * @param client
@@ -84,6 +112,52 @@ void guac_vnc_update(rfbClient* client, int x, int y, int w, int h);
 void guac_vnc_copyrect(rfbClient* client, int src_x, int src_y, int w, int h,
         int dest_x, int dest_y);
 
+/**
+ * Allocates a new VNC display update module, which will keep track of the data
+ * needed to handle display updates.
+ *
+ * @param client
+ *     The guac_client instance handling the relevant VNC connection.
+ *
+ * @return
+ *     A newly-allocated VNC display update module.
+ */
+guac_vnc_display* guac_vnc_display_update_alloc(guac_client* client);
+
+/**
+ * Frees the resources associated with the data structure that keeps track of
+ * items related to VNC display updates. Only resources specific to Guacamole
+ * are freed. Resources that are part of the rfbClient will be freed separately.
+ * If no resources are currently allocated for Display Update support, this
+ * function has no effect.
+ *
+ * @param display
+ *     The display update module to free.
+ */
+void guac_vnc_display_update_free(guac_vnc_display* display);
+
+/**
+ * Attempts to set the display size of the remote server to the size requested
+ * by the client, usually as part of a client (browser) resize, if supported by
+ * both the VNC client and the remote server.
+ *
+ * @param display
+ *     The VNC display update object that tracks information related to display
+ *     update requests.
+ *
+ * @param rfb_client
+ *     The data structure containing the VNC client that is used by this
+ *     connection.
+ *
+ * @param width
+ *     The width that is being requested, in pixels.
+ *
+ * @param height
+ *     The height that is being requested, in pixels.
+ */
+void guac_vnc_display_set_size(guac_vnc_display* display, rfbClient* rfb_client,
+        int width, int height);
+
 /**
  * Sets the pixel format to request of the VNC server. The request will be made
  * during the connection handshake with the VNC server using the values

src/protocols/vnc/input.c

@@ -21,6 +21,7 @@
 
 #include "common/cursor.h"
 #include "common/display.h"
+#include "display.h"
 #include "vnc.h"
 
 #include <guacamole/recording.h>
@@ -64,3 +65,14 @@ int guac_vnc_user_key_handler(guac_user* user, int keysym, int pressed) {
     return 0;
 }
 
+int guac_vnc_user_size_handler(guac_user* user, int width, int height) {
+
+    guac_vnc_client* vnc_client = (guac_vnc_client*) user->client->data;
+    rfbClient* rfb_client = vnc_client->rfb_client;
+
+    /* Send display update */
+    guac_vnc_display_set_size(vnc_client->vnc_display, rfb_client, width, height);
+
+    return 0;
+
+}

src/protocols/vnc/input.h

@@ -34,5 +34,9 @@ guac_user_mouse_handler guac_vnc_user_mouse_handler;
  */
 guac_user_key_handler guac_vnc_user_key_handler;
 
-#endif
+/**
+ * Handler for Guacamole user resize events.
+ */
+guac_user_size_handler guac_vnc_user_size_handler;
 
+#endif // GUAC_VNC_INPUT_H

src/protocols/vnc/user.c

@@ -91,6 +91,9 @@ int guac_vnc_user_join_handler(guac_user* user, int argc, char** argv) {
             user->file_handler = guac_vnc_sftp_file_handler;
 #endif
 
+        /* Handle display size changes. */
+        user->size_handler = guac_vnc_user_size_handler;
+
     }
 
     /**

src/protocols/vnc/vnc.h

@@ -26,6 +26,7 @@
 #include "common/display.h"
 #include "common/iconv.h"
 #include "common/surface.h"
+#include "display.h"
 #include "settings.h"
 
 #include <guacamole/client.h>
@@ -63,6 +64,11 @@ typedef struct guac_vnc_client {
     pthread_mutex_t tls_lock;
 #endif
 
+    /**
+     * Lock which synchronizes messages sent to VNC server.
+     */
+    pthread_mutex_t message_lock;
+
     /**
      * The underlying VNC client.
      */
@@ -135,6 +141,11 @@ typedef struct guac_vnc_client {
      */
     guac_iconv_write* clipboard_writer;
 
+    /**
+     * VNC display update module.
+     */
+    guac_vnc_display* vnc_display;
+
 } guac_vnc_client;
 
 /**