ui: avoid sending framebuffer updates outside client desktop bounds
We plan framebuffer update rects based on the VNC server surface. If the
client doesn't support desktop resize, then the client bounds may differ
from the server surface bounds. VNC clients may become upset if we then
send an update message outside the bounds of the client desktop.
This takes the approach of clamping the rectangles from the worker
thread immediately before sending them. This may sometimes results in
sending a framebuffer update message with zero rectangles.
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20210311182957.486939-3-berrange@redhat.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
diff --git a/ui/vnc-jobs.c b/ui/vnc-jobs.c
index dbbfbef..4562bf8 100644
--- a/ui/vnc-jobs.c
+++ b/ui/vnc-jobs.c
@@ -32,6 +32,7 @@
#include "qemu/sockets.h"
#include "qemu/main-loop.h"
#include "block/aio.h"
+#include "trace.h"
/*
* Locking:
@@ -94,6 +95,8 @@
{
VncRectEntry *entry = g_new0(VncRectEntry, 1);
+ trace_vnc_job_add_rect(job->vs, job, x, y, w, h);
+
entry->rect.x = x;
entry->rect.y = y;
entry->rect.w = w;
@@ -190,6 +193,8 @@
local->zlib = orig->zlib;
local->hextile = orig->hextile;
local->zrle = orig->zrle;
+ local->client_width = orig->client_width;
+ local->client_height = orig->client_height;
}
static void vnc_async_encoding_end(VncState *orig, VncState *local)
@@ -202,6 +207,34 @@
orig->lossy_rect = local->lossy_rect;
}
+static bool vnc_worker_clamp_rect(VncState *vs, VncJob *job, VncRect *rect)
+{
+ trace_vnc_job_clamp_rect(vs, job, rect->x, rect->y, rect->w, rect->h);
+
+ if (rect->x >= vs->client_width) {
+ goto discard;
+ }
+ rect->w = MIN(vs->client_width - rect->x, rect->w);
+ if (rect->w == 0) {
+ goto discard;
+ }
+
+ if (rect->y >= vs->client_height) {
+ goto discard;
+ }
+ rect->h = MIN(vs->client_height - rect->y, rect->h);
+ if (rect->h == 0) {
+ goto discard;
+ }
+
+ trace_vnc_job_clamped_rect(vs, job, rect->x, rect->y, rect->w, rect->h);
+ return true;
+
+ discard:
+ trace_vnc_job_discard_rect(vs, job, rect->x, rect->y, rect->w, rect->h);
+ return false;
+}
+
static int vnc_worker_thread_loop(VncJobQueue *queue)
{
VncJob *job;
@@ -260,14 +293,17 @@
goto disconnected;
}
- n = vnc_send_framebuffer_update(&vs, entry->rect.x, entry->rect.y,
- entry->rect.w, entry->rect.h);
+ if (vnc_worker_clamp_rect(&vs, job, &entry->rect)) {
+ n = vnc_send_framebuffer_update(&vs, entry->rect.x, entry->rect.y,
+ entry->rect.w, entry->rect.h);
- if (n >= 0) {
- n_rectangles += n;
+ if (n >= 0) {
+ n_rectangles += n;
+ }
}
g_free(entry);
}
+ trace_vnc_job_nrects(&vs, job, n_rectangles);
vnc_unlock_display(job->vs->vd);
/* Put n_rectangles at the beginning of the message */
