From e90f005a1066075f0d79531ede763fadb51f61ee 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 | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/lib/core-net/vhost.c b/lib/core-net/vhost.c
index 0ba451cdb..852155bd6 100644
--- a/lib/core-net/vhost.c
+++ b/lib/core-net/vhost.c
@@ -1272,8 +1272,23 @@ lws_vhost_destroy1(struct lws_vhost *vh)
 
 				if (v->lserv_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(vh->lserv_wsi);
 					lws_vhost_bind_wsi(v, v->lserv_wsi);
+
+					/*
+					 * ... remove the fake wsi bind
+					 */
+					v->count_bound_wsi--;
+
 					vh->lserv_wsi = NULL;
 				}