Crash of mosquitto broker on Windows when client disconnects from websocket connection

[krismattheus]

There is a bug in the callback_mqtt function in websockets.c, that causes a crash of the mosquitto broker on Windows when a client closes its websocket connection.

mosquitto/src/websockets.c

Line 249 in 19fbbd8

if(mosq->sock > 0){

should be changed to:

if((int)mosq->sock > 0){
or
if(mosq->sock != INVALID_SOCKET){

A socket on Windows is an unsigned int, so this test succeeds even when the value is INVALID_SOCKET.
This invalid test causes the HASH_DELETE to be called again when the socket is already closed. This causes the crash. After changing the code the crash no longer happens.

Some extra info:
We use mosquitto version 1.5.5 and libwebsockets 3.0.1

[ralight]

Thanks, that's fixed in my local branch and will be pushed as part of 1.5.6 shortly.