ospf6d: ospfv3-setsocket-retry.patch

ospf6d: ospfv3-setsocket-retry.patch

SYMPTOM:

With quagga running on Linux, 'ifdown <if-name>' followed by 'ifup <ifname>
can cause OSPFv3 to not receive Hello packets on the interface.

ISSUE:

Operating System's interface IPv6 readiness may not be guaranteed at the
time of interface-up event. Thats because the ipv6 components in an OS may
also be listening to the same interface-up event that (in this case) is
relayed to OSPFv3.

In this failure case, setsockopt with option IPV6_JOIN_GROUP on the interface
returned EINVAL.

Error logs -
OSPF6: Zebra Interface state change: swp1 index 3 flags 11043 metric 1 mtu 1500
OSPF6: Interface Event swp1: [InterfaceUp]
OSPF6: Network: setsockopt (20) on ifindex 3 failed: Invalid argument

FIX:

To take care of this possible race condition, any address-family related
setting should be retried. Given it's a rare condition and window of this
race should be short, the patch adds a limited retry mechanism for the
IPV6 membership setting on the socket.

Signed-off-by: Vipin Kumar <vipin@cumulusnetworks.com>
Reviewed-by: Dinesh Dutt <ddutt@cumulusnetworks.com>
             Satish Ashok <sashok@cumulusnetworks.com>