Propagete NEWADDR for unnumbered interfaces

[pimvanpelt]

linux-cp and lcpng do not honor address additions/deletions on unnumbered interfaces. Take the following example:

root@vpp0-3:/usr/share/vpp/api# vppctl lcp lcp-sync-unnumbered on
root@vpp0-3:/usr/share/vpp/api# ip -br a
lo               UNKNOWN        127.0.0.1/8 ::1/128 
loop0            UNKNOWN        192.168.10.3/32 2001:678:d78:200::3/128 fe80::dcad:ff:fe00:0/64 
e0               UP             192.168.10.3/32 2001:678:d78:200::3/128 fe80::5054:ff:fef0:1130/64 
e1               DOWN           
e2               DOWN           
e3               DOWN           
root@vpp0-3:/usr/share/vpp/api# ip addr add 192.0.2.1/32 dev loop0
root@vpp0-3:/usr/share/vpp/api# ip -br a
lo               UNKNOWN        127.0.0.1/8 ::1/128 
loop0            UNKNOWN        192.168.10.3/32 192.0.2.1/32 2001:678:d78:200::3/128 fe80::dcad:ff:fe00:0/64 
e0               UP             192.168.10.3/32 2001:678:d78:200::3/128 fe80::5054:ff:fef0:1130/64 
e1               DOWN           
e2               DOWN           
e3               DOWN           
root@vpp0-3:/usr/share/vpp/api# ip -br a
lo               UNKNOWN        127.0.0.1/8 ::1/128 
loop0            UNKNOWN        192.168.10.3/32 192.0.2.1/32 2001:678:d78:200::3/128 fe80::dcad:ff:fe00:0/64 
e0               UP             192.168.10.3/32 2001:678:d78:200::3/128 fe80::5054:ff:fef0:1130/64 
e1               DOWN           
e2               DOWN           
e3               DOWN           
root@vpp0-3:/usr/share/vpp/api# vppctl show int addr
GigabitEthernet10/0/0 (up): 
  unnumbered, use loop0
  L3 192.168.10.3/32
  L3 192.0.2.1/32
  L3 2001:678:d78:200::3/128
GigabitEthernet10/0/1 (dn):
GigabitEthernet10/0/2 (dn):
GigabitEthernet10/0/3 (dn):
local0 (dn):
loop0 (up):
  L3 192.168.10.3/32
  L3 192.0.2.1/32
  L3 2001:678:d78:200::3/128
tap0 (up):
tap1 (up):
tap2 (up):
tap3 (up):
tap4 (up):

LCP will consume the addition of NEWADDR/DELADDR for loop0; and e0, because it's unnumbered on loop0, will receive the IPv4 address in VPP, but not Linux.

Two possible solutions:

1. Propagate the NEWADDR/DELADDR to all unnumbered interfaces keyed off of the loop0 interface (change to linux-cp)
2. Generate a new ip[46]_add_del_interface_address_callback_t to notify all watches of new addresses on unnumbered interfaces