From 97b8abf16cb5ebca14f71f0036eef50c9cd88a9c Mon Sep 17 00:00:00 2001
From: James Smith <jsmith@ecoscentric.com>
Date: Tue, 24 Jul 2012 10:34:09 -0600
Subject: [PATCH] Fix bug #36857: tcp_listen_dual_with_backlog() only works
 with ANY address

Change-Id: I092a4c9978d88040214fc44a4c4b353be618d76c
---
 src/core/tcp.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/src/core/tcp.c b/src/core/tcp.c
index 05e7c7d8..a0cbb159 100644
--- a/src/core/tcp.c
+++ b/src/core/tcp.c
@@ -591,11 +591,12 @@ tcp_listen_dual_with_backlog(struct tcp_pcb *pcb, u8_t backlog)
 {
   struct tcp_pcb *lpcb;
 
-  if (!ipX_addr_isany(PCB_ISIPV6(pcb), &pcb->local_ip)) {
-    return NULL;
-  }
   lpcb = tcp_listen_with_backlog(pcb, backlog);
-  if (lpcb != NULL) {
+  if ((lpcb != NULL) &&
+      ipX_addr_isany(PCB_ISIPV6(pcb), &pcb->local_ip)) {
+    /* The default behavior is to accept connections on either
+     * IPv4 or IPv6, if not bound. */
+    /* @see NETCONN_FLAG_IPV6_V6ONLY for changing this behavior */
     ((struct tcp_pcb_listen*)lpcb)->accept_any_ip_version = 1;
   }
   return lpcb;