ctdb-scripts: Wait until IPv6 addresses are not "tentative"

There are a few potential failure modes when adding an IPv6 address.
It takes a little while of duplicate address detection to complete, so
wait for a while.  After a timeout, also need to check to see if
duplicate address detection failed - if it did then actually drop the
IP address.

This really needs some careful thinking.  If CTDB disappears on a node
but the node's IP addresses are still on interfaces then the above
failure mode could cause the takeover nodes to become banned.

Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>

1 files changed, 23 insertions, 0 deletions

diff --git a/ctdb/config/functions b/ctdb/config/functions
index b9f3638a7d..23cb2364e3 100755
--- a/ctdb/config/functions
+++ b/ctdb/config/functions
@@ -869,6 +869,29 @@ add_ip_to_iface ()
 	echo "Failed to add $_ip/$_maskbits on dev $_iface"
 	return 1
     }
+
+    # Wait 5 seconds for IPv6 addresses to stop being tentative...
+    if [ -z "$_bcast" ] ; then
+	for _x in $(seq 1 10) ; do
+	    ip addr show to "${_ip}/128" | grep -q "tentative" || break
+	    sleep 0.5
+	done
+
+	# If the address was a duplicate then it won't be on the
+	# interface so flag an error.
+	_t=$(ip addr show to "${_ip}/128")
+	case "$_t" in
+	    "")
+		echo "Failed to add $_ip/$_maskbits on dev $_iface"
+		return 1
+		;;
+	    *tentative*|*dadfailed*)
+		echo "Failed to add $_ip/$_maskbits on dev $_iface"
+		ip addr del "$_ip/$_maskbits" dev "$_iface"
+		return 1
+		;;
+	esac
+    fi
 }
 
 delete_ip_from_iface()