fix null protocol dereference when closing session

Thanks to Christopher Baker for pointing out that when we close a session,
if the close is coming before a protocol was negotiated for the connection
or when the protocol was otherwise left at NULL, we'll blow a segfault.

This implements his proposed fix.

Reported-by: Christopher Baker <me@christopherbaker.net>
Signed-off-by: Andy Green <andy@warmcat.com>

diff --git a/lib/libwebsockets.c b/lib/libwebsockets.c
index b3e6023..a857bea 100644 (file)
--- a/lib/libwebsockets.c
+++ b/lib/libwebsockets.c
@@ -187,7 +187,8 @@ libwebsocket_close_and_free_session(struct libwebsocket_context *this,
 
        /* tell the user it's all over for this guy */
 
-       if (wsi->protocol->callback && old_state == WSI_STATE_ESTABLISHED)
+       if (wsi->protocol && wsi->protocol->callback &&
+                                            old_state == WSI_STATE_ESTABLISHED)
                wsi->protocol->callback(this, wsi, LWS_CALLBACK_CLOSED,
                                                      wsi->user_space, NULL, 0);