From 7b4a20f64eba19ce98f5dfa9b325c5bf87890bd1 Mon Sep 17 00:00:00 2001
From: Mario Kicherer <dev@kicherer.org>
Date: Thu, 10 Oct 2024 15:03:27 +0200
Subject: [PATCH] coap_join_mcast_group_intf: fix interface selection on
 windows

---
 src/coap_net.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/src/coap_net.c b/src/coap_net.c
index 24b3c7fa33..9c323e2819 100644
--- a/src/coap_net.c
+++ b/src/coap_net.c
@@ -4706,7 +4706,14 @@ coap_join_mcast_group_intf_lkd(coap_context_t *ctx, const char *group_name,
       }
     }
   }
-#endif /* ! _WIN32 */
+#else /* _WIN32 */
+  /*
+   * On Windows this function ignores the ifname variable so we unset this
+   * variable on this platform in any case in order to enable the interface
+   * selection from the bind address below.
+   */
+  ifname = 0;
+#endif /* _WIN32 */
 
   /* Add in mcast address(es) to appropriate interface */
   for (ainfo = resmulti; ainfo != NULL; ainfo = ainfo->ai_next) {