From c8176085df983591dd12f9aaefa87c9dcbae2afd Mon Sep 17 00:00:00 2001
From: Andy Green <andy@warmcat.com>
Date: Mon, 12 Jul 2021 06:12:05 +0100
Subject: [PATCH] vhost: listen: protect listen port transfer between

...vhosts from vh destroy on zero refcount

https://github.com/warmcat/libwebsockets/issues/2343
---
 lib/core-net/vhost.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/lib/core-net/vhost.c b/lib/core-net/vhost.c
index ba0de1768..8fa3d08bd 100644
--- a/lib/core-net/vhost.c
+++ b/lib/core-net/vhost.c
@@ -1349,8 +1349,21 @@ lws_vhost_destroy1(struct lws_vhost *vh)
 						  &v->listen_wsi);
 
 				/* req cx + vh lock */
+				/*
+				 * If the vhost sees it's being destroyed and
+				 * in the unbind the number of wsis bound to
+				 * it falls to zero, it will destroy the
+				 * vhost opportunistically before we can
+				 * complete the transfer.  Add a fake wsi
+				 * bind temporarily to disallow this...
+				 */
+				v->count_bound_wsi++;
 				__lws_vhost_unbind_wsi(wsi);
 				lws_vhost_bind_wsi(v, wsi);
+				/*
+				 * ... remove the fake wsi bind
+				 */
+				v->count_bound_wsi--;
 				break;
 			}
 		} lws_end_foreach_ll(v, vhost_next);