fix link id for p2p interfaces router lsa type 3 link

[Remi Locherer]

Hi,

when ospfd originates LSAs for p2p interfaces it puts the interface
address into the link id field where it should use the network address.

The issue was reported by Mitchell Krome on tech@ and one part of the
problem was fixed in rde_spf.c revision 1.77.
--> https://marc.info/?t=155392640800001&r=1&w=2

This diff fixes the LSAs ospfd sends out.

OK?

Remi


Index: ospfe.c
===================================================================
RCS file: /cvs/src/usr.sbin/ospfd/ospfe.c,v
retrieving revision 1.103
diff -u -p -r1.103 ospfe.c
--- ospfe.c     27 Sep 2018 12:34:06 -0000      1.103
+++ ospfe.c     22 Apr 2019 08:47:36 -0000
@@ -908,7 +908,8 @@ orig_rtr_lsa(struct area *area)
                                        rtr_link.id = nbr->addr.s_addr;
                                        rtr_link.data = 0xffffffff;
                                } else {
-                                       rtr_link.id = iface->addr.s_addr;
+                                       rtr_link.id = iface->addr.s_addr &
+                                                     iface->mask.s_addr;
                                        rtr_link.data = iface->mask.s_addr;
                                }
                                rtr_link.type = LINK_TYPE_STUB_NET;