Stop Windows PuTTY becoming unresponsive if server floods us.

[PuTTY.git] / windows / window.c

diff --git a/windows/window.c b/windows/window.c
index 6ee534348160f59365057de3411829659b50a12c..ebcecac7053b7cb795ef28b546bf350f90abb936 100644 (file)
--- a/windows/window.c
+++ b/windows/window.c
@@ -888,12 +888,34 @@ int WINAPI WinMain(HINSTANCE inst, HINSTANCE prev, LPSTR cmdline, int show)
        } else
            sfree(handles);
 
-       if (PeekMessage(&msg, NULL, 0, 0, PM_REMOVE)) {
+       while (PeekMessage(&msg, NULL, 0, 0, PM_REMOVE)) {
            if (msg.message == WM_QUIT)
                goto finished;         /* two-level break */
 
            if (!(IsWindow(logbox) && IsDialogMessage(logbox, &msg)))
                DispatchMessage(&msg);
+
+            /*
+             * WM_NETEVENT messages seem to jump ahead of others in
+             * the message queue. I'm not sure why; the docs for
+             * PeekMessage mention that messages are prioritised in
+             * some way, but I'm unclear on which priorities go where.
+             *
+             * Anyway, in practice I observe that WM_NETEVENT seems to
+             * jump to the head of the queue, which means that if we
+             * were to only process one message every time round this
+             * loop, we'd get nothing but NETEVENTs if the server
+             * flooded us with data, and stop responding to any other
+             * kind of window message. So instead, we keep on round
+             * this loop until we've consumed at least one message
+             * that _isn't_ a NETEVENT, or run out of messages
+             * completely (whichever comes first). And we don't go to
+             * run_toplevel_callbacks (which is where the netevents
+             * are actually processed, causing fresh NETEVENT messages
+             * to appear) until we've done this.
+             */
+            if (msg.message != WM_NETEVENT)
+                break;
        }
 
         run_toplevel_callbacks();
@@ -2234,9 +2256,10 @@ static LRESULT CALLBACK WndProc(HWND hwnd, UINT message,
                 * Flush the line discipline's edit buffer in the
                 * case where local editing has just been disabled.
                 */
-               ldisc_configure(ldisc, conf);
-               if (ldisc)
+               if (ldisc) {
+                    ldisc_configure(ldisc, conf);
                    ldisc_send(ldisc, NULL, 0, 0);
+                }
                if (pal)
                    DeleteObject(pal);
                logpal = NULL;