Subject: [PATCH] Check response existence on upgrade
From: [email-masked]
Date: Thu, 4 May 2017 21:47:38 +0200

When a connection upgrade is requested and when the
request sent an error reply, the response is most of
the time already sent when the test on
connection->response->upgrade_handler is made, leading
to dereferencing NULL.

Two possibilities exist:

  NULL == connection->response || NULL == connection->response->upgrade_handler

or

  NULL != connection->response && NULL == connection->response->upgrade_handler

The first is prefered because it is probably safer to close the connection
in that case.

Upstream-Status: Accepted [https://gnunet.org/git/libmicrohttpd.git/commit/?id=b4216c60fdb5b48f6cfec416301fc63a1167e6cd]

Change-Id: Ie6e7fc165f7fe3635ade0952bb34a0b937d38716
Signed-off-by: José Bollo <[email-masked]>
Signed-off-by: José Bollo <[email-masked]>
---
 src/microhttpd/connection.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/microhttpd/connection.c b/src/microhttpd/connection.c
index 4753d6e..91a4492 100644
--- a/src/microhttpd/connection.c
+++ b/src/microhttpd/connection.c
@@ -882,7 +882,7 @@ keepalive_possible (struct MHD_Connection *connection)
 #ifdef UPGRADE_SUPPORT
     if ( (MHD_str_equal_caseless_ (end,
                                    "upgrade")) &&
-         (NULL == connection->response->upgrade_handler) )
+         (NULL == connection->response || NULL == connection->response->upgrade_handler) )
       return MHD_NO;
 #endif /* UPGRADE_SUPPORT */
 
-- 
2.9.3