pim-anycast-rp: Add limited support for secondary addresses.

Anycast requires that the lo interface be associated with multiple
addresses. One is the anycast IP address (which is the same on all RPs
participating in RP redundancy) and the second is the unique IP address
that will be used as the router id by routing protocols.

To accomodate that we maintain a list of secondary addresses per-pim iface
and allow any of them to be the RP address. This lets the I_am_RP macro
succeed on anycast RPs.

Note that the support is limited i.e. we don't actually advertise a
secondary list to the neighbors. This is assuming the anycast IP will never
be used as a router id i.e. will never be an RPF neighbor.

Sample output:
==============
dell-s6000-04# sh ip pim interface lo
Interface : lo
State     : up
Address   : 100.1.1.1 (primary)
            100.1.1.2
            100.1.1.3
            100.1.2.1
>>>>>>> SNIP >>>>>>>>>>>>>>>
dell-s6000-04# sh ip pim interface lo json
{
  "lo":{
    "name":"lo",
    "state":"up",
    "address":"100.1.1.1",
    "index":1,
    "lanDelayEnabled":true,
    "secondaryAddressList":[
      "100.1.1.2",
      "100.1.1.3",
      "100.1.2.1"
    ],
>>>>>>> SNIP >>>>>>>>>>>>>>>
dell-s6000-04#sh ip pim rp-info
RP address       group/prefix-list   OIF         I am RP
100.1.2.1        224.0.0.0/4         lo          yes
dell-s6000-04#

Signed-off-by: Anuradha Karuppiah <anuradhak@cumulusnetworks.com>
Acked-by: Donald Sharp <sharpd@cumulusnetworks.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/pimd/pim_rp.h b/pimd/pim_rp.h
index 1e1912ff96..b32228ed49 100644
--- a/pimd/pim_rp.h
+++ b/pimd/pim_rp.h
@@ -32,8 +32,9 @@ int pim_rp_config_write (struct vty *vty);
 
 int pim_rp_setup (void);
 
-void pim_rp_check_rp (struct in_addr old, struct in_addr new);
 int pim_rp_i_am_rp (struct in_addr group);
+void pim_rp_check_on_if_add(struct pim_interface *pim_ifp);
+void pim_i_am_rp_re_evaluate(void);
 
 int pim_rp_check_is_my_ip_address (struct in_addr group, struct in_addr dest_addr);