Add 'primary' configuration option.

sysdep/unix/krt.Y

@@ -68,6 +68,7 @@ kif_proto_start: proto_start DEVICE {
      cf_kif = this_proto = proto_config_new(&proto_unix_iface, sizeof(struct kif_config));
      this_proto->preference = DEF_PREF_DIRECT;
      THIS_KIF->scan_time = 60;
+     init_list(&THIS_KIF->primary);
      krt_if_construct(THIS_KIF);
    }
  ;
@@ -81,6 +82,13 @@ kif_item:
       /* Scan time of 0 means scan on startup only */
       THIS_KIF->scan_time = $3;
    }
+ | PRIMARY TEXT prefix_or_ipa {
+     struct kif_primary_item *kpi = cfg_alloc(sizeof (struct kif_primary_item));
+     kpi->pattern = $2;
+     kpi->prefix = $3.addr;
+     kpi->pxlen = $3.len;
+     add_tail(&THIS_KIF->primary, &kpi->n);
+   }
  ;
 
 CF_CODE

sysdep/unix/krt.h

@@ -86,10 +86,18 @@ void krt_got_route_async(struct krt_proto *p, struct rte *e, int new);
 
 extern struct protocol proto_unix_iface;
 
+struct kif_primary_item {
+  node n;
+  byte *pattern;
+  ip_addr prefix;
+  int pxlen;
+};
+
 struct kif_config {
   struct proto_config c;
   struct krt_if_params iface;
   int scan_time;		/* How often we re-scan interfaces */
+  list primary;			/* Preferences for primary addresses */
 };
 
 struct kif_proto {