From 7e9b45c929bdc07438d02a01a8ef2095004ca02c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Odd=20Str=C3=A5b=C3=B8?= <oddstr13@openshell.no>
Date: Fri, 8 Feb 2019 18:07:58 +0100
Subject: [PATCH] Fixes issue #5744

Initialize UdpContext `_pcb->local_ip.type` with `IPADDR_TYPE_ANY` in dual-stack mode.
---
 libraries/ESP8266WiFi/src/include/UdpContext.h | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/libraries/ESP8266WiFi/src/include/UdpContext.h b/libraries/ESP8266WiFi/src/include/UdpContext.h
index e1be24c13b..3f8623a0d4 100644
--- a/libraries/ESP8266WiFi/src/include/UdpContext.h
+++ b/libraries/ESP8266WiFi/src/include/UdpContext.h
@@ -51,6 +51,12 @@ class UdpContext
     , _tx_buf_offset(0)
     {
         _pcb = udp_new();
+// Defaults to IPADDR_TYPE_V4 (_pcb initialized with all zeroes)
+#if LWIP_IPV4 && LWIP_IPV6
+        _pcb->local_ip.type = IPADDR_TYPE_ANY;
+#elif LWIP_IPV6
+        _pcb->local_ip.type = IPADDR_TYPE_V6;
+#endif
 #ifdef LWIP_MAYBE_XCC
         _mcast_ttl = 1;
 #endif