zebra: NetBSD: get IPSRCSEL preference value from kernel

fetch the address preference value from the kernel through
SIOCGIFADDRPREF and pass it to quagga through connected_add_ipv4,
which stores it in struct connected->preference.

IPSRCSEL is a NetBSD kernel option(4), documented in in_getifa(9) and
is available since NetBSD 4.0 but not enabled in default GENERIC.

1 files changed, 3 insertions, 0 deletions

diff --git a/lib/if.h b/lib/if.h
index 28faddf3..1b29f470 100644
--- a/lib/if.h
+++ b/lib/if.h
@@ -175,6 +175,9 @@ struct connected
 
   /* scope value, Linux only */
   unsigned scope;
+
+  /* address preference, NetBSD >=4.0 with option IPSRCSEL, in_getifa(9) */
+  int preference;
 };
 
 /* Does the destination field contain a peer address? */