From 9801c5efcf8c1774d9c807ebd5d27ac7049ad993 Mon Sep 17 00:00:00 2001
From: Michal Srb <michalsrb@gmail.com>
Date: Wed, 29 Mar 2017 17:00:30 +0300
Subject: Fix checkNoWait logic in SSecurityPlain.

Currently it proceeds only if there aren't enough data in queue and then it blocks waiting.
Also the required amount to receive from network is (ulen + plen), not (ulen + plen + 2).

This allowed not authenticated clients to deny service to everyone.

diff --git a/common/rfb/SSecurityPlain.cxx b/common/rfb/SSecurityPlain.cxx
index f5a5cc7..0531549 100644
--- a/common/rfb/SSecurityPlain.cxx
+++ b/common/rfb/SSecurityPlain.cxx
@@ -92,7 +92,7 @@ bool SSecurityPlain::processMsg(SConnection* sc)
   }
 
   if (state == 1) {
-    if (is->checkNoWait(ulen + plen + 2))
+    if (!is->checkNoWait(ulen + plen))
       return false;
     state = 2;
     pw = new char[plen + 1];