Avoid invalid read when buffer is full

nread is an unsigned value and was overflowing causing
buffer read issues
add null terminator at end only if full msg has been read

Signed-off-by: Tom Flynn <tom.flynn@gmail.com>

libopflex/comms/CommunicationPeer.cpp

@@ -190,9 +190,7 @@ void CommunicationPeer::readBufNoNull(char* buffer, size_t nread) {
         return;
     }
 
-    buffer[nread++] = '\0';
-
-    while ((--nread > 0) && connected_) {
+    while ((nread != 0 && --nread > 0) && connected_) {
         size_t chunk_size = readChunk(buffer);
         if (chunk_size == 0) {
             break;

libopflex/comms/transport/PlainText.cpp

@@ -89,6 +89,10 @@ void Cb< PlainText >::on_read(uv_stream_t * h, ssize_t nread, uv_buf_t const * b
                 (buf->len > static_cast< size_t >(nread))
             );
         } else {
+            // add null terminator to indicate end of message
+            if (nread && buf->len != (size_t)nread) {
+                buf->base[nread++] = '\0';
+            }
             peer->readBufNoNull(buf->base, nread);
         }
     }