viewer: exit when user specifies both -via and -listen parameters


git-svn-id: svn://svn.code.sf.net/p/tigervnc/code/trunk@5048 3789f03b-4d11-0410-bbf8-ca57d06f2519
diff --git a/vncviewer/vncviewer.cxx b/vncviewer/vncviewer.cxx
index 8e9622a..6cf1d89 100644
--- a/vncviewer/vncviewer.cxx
+++ b/vncviewer/vncviewer.cxx
@@ -444,7 +444,15 @@
 
   Socket *sock = NULL;
 
-  if(listenMode) {
+  /* Specifying -via and -listen together is nonsense */
+  if (listenMode && strlen(via.getValueStr()) > 0) {
+    vlog.error("Parameters -listen and -via are incompatible");
+    fl_alert("Parameters -listen and -via are incompatible");
+    exit_vncviewer();
+    return 1;
+  }
+
+  if (listenMode) {
     try {
       int port = 5500;
       if (isdigit(vncServerName[0]))