From 91268fa0ba49446d9a15c75bd53599f8bd5e2470 Mon Sep 17 00:00:00 2001
From: David Wragg <david@wragg.org>
Date: Fri, 5 Sep 2014 12:51:41 +0100
Subject: [PATCH] Check that 'iptables -w' is supported before using it

'-w' was only introduced in a recent version of iptables.  It means
"Wait for the xtables lock", so it seems reasonable to proceed without
it for older versions.
---
 weaver/weave | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/weaver/weave b/weaver/weave
index 4b323d7a..4928526b 100755
--- a/weaver/weave
+++ b/weaver/weave
@@ -49,9 +49,16 @@ create_bridge() {
 }
 
 add_nat_rule() {
-    if ! iptables -w -t nat -C $1 >/dev/null 2>&1
+    if [ -z "$CHECKED_IPTABLES_W" ] ; then
+        if iptables -S -w >/dev/null 2>&1 ; then
+            IPTABLES_W=-w
+        fi
+        CHECKED_IPTABLES_W=1
+    fi
+
+    if ! iptables $IPTABLES_W -t nat -C $1 >/dev/null 2>&1
     then
-        iptables -w -t nat -A $1 >/dev/null
+        iptables $IPTABLES_W -t nat -A $1 >/dev/null
     fi
 }