Filter: Allow setting the 'onlink' route attribute in filters

Add static route attribute to set onlink flag for route next hop. Can be
used to build a dynamically routed IP-in-IP overlay network. Usage:

     ifname = "tunl0";
     onlink = true;
     gw = bgp_next_hop;

diff --git a/doc/bird.sgml b/doc/bird.sgml
index 50657ebf872a69b86d8faee5c2d5cd2cdd203776..001fcbd40af6f785af91d23c74a9f9a8e7ce34ee 100644 (file)
--- a/doc/bird.sgml
+++ b/doc/bird.sgml
@@ -1816,6 +1816,14 @@ Common route attributes are:
        creation/removal. Zero is returned for routes with undefined outgoing
        interfaces. Read-only.
 
+       <tag><label id="rta-onlink"><m/bool/ onlink</tag>
+       Onlink flag means that the specified nexthop is accessible on the
+       interface regardless of IP prefixes configured on the interface.
+       The attribute can be used to configure such next hops by first setting
+       <cf/onlink = true/ and <cf/ifname/, and then setting <cf/gw/. Possible
+       use case for setting this flag is to automatically build overlay IP-IP
+       networks on linux.
+
        <tag><label id="rta-weight"><m/int/ weight</tag>
        Multipath weight of route next hops. Valid values are 1-256. Reading
        returns the weight of the first next hop, setting it sets weights of all

diff --git a/filter/config.Y b/filter/config.Y
index 1d9d9aa970ee1b7734f727ef80ee334578537d09..a1e5e9f17fd4bb31213b6ccdf3b063b009800d90 100644 (file)
--- a/filter/config.Y
+++ b/filter/config.Y
@@ -305,7 +305,7 @@ CF_KEYWORDS(FUNCTION, PRINT, PRINTN, UNSET, RETURN,
        IF, THEN, ELSE, CASE,
        FOR, IN, DO,
        TRUE, FALSE, RT, RO, UNKNOWN, GENERIC,
-       FROM, GW, NET, MASK, PROTO, SOURCE, SCOPE, DEST, IFNAME, IFINDEX, WEIGHT, GW_MPLS,
+       FROM, GW, NET, MASK, PROTO, SOURCE, SCOPE, DEST, IFNAME, IFINDEX, WEIGHT, GW_MPLS, ONLINK,
        PREFERENCE,
        ROA_CHECK, ASN, SRC, DST,
        IS_V4, IS_V6,
@@ -795,6 +795,7 @@ static_attr:
  | WEIGHT  { $$ = f_new_static_attr(T_INT,        SA_WEIGHT,   0); }
  | PREFERENCE { $$ = f_new_static_attr(T_INT,    SA_PREF,      0); }
  | GW_MPLS { $$ = f_new_static_attr(T_INT,        SA_GW_MPLS,  0); }
+ | ONLINK  { $$ = f_new_static_attr(T_BOOL,       SA_ONLINK,   0); }
  ;
 
 term:

diff --git a/filter/data.h b/filter/data.h
index 700609e9de8cc2ef88aef2565281d9f41f07b64a..b3767f7bc7d58df3150297923d0551f8cb6f88c1 100644 (file)
--- a/filter/data.h
+++ b/filter/data.h
@@ -102,6 +102,7 @@ enum f_sa_code {
   SA_WEIGHT,
   SA_PREF,
   SA_GW_MPLS,
+  SA_ONLINK,
 } PACKED;
 
 /* Static attribute definition (members of struct rta) */

diff --git a/filter/f-inst.c b/filter/f-inst.c
index 2d2a30e4f7da5a2150e360086dddee76e9091409..e4b47ff48499fed83a4a103b82ebe8d4a66812f8 100644 (file)
--- a/filter/f-inst.c
+++ b/filter/f-inst.c
@@ -694,6 +694,7 @@
       case SA_WEIGHT:  RESULT(sa.f_type, i, rta->nh.weight + 1); break;
       case SA_PREF:    RESULT(sa.f_type, i, rta->pref); break;
       case SA_GW_MPLS: RESULT(sa.f_type, i, rta->nh.labels ? rta->nh.label[0] : MPLS_NULL); break;
+      case SA_ONLINK:  RESULT(sa.f_type, i, rta->nh.flags & RNF_ONLINK ? 1 : 0); break;
 
       default:
        bug("Invalid static attribute access (%u/%u)", sa.f_type, sa.sa_code);
@@ -720,8 +721,8 @@
       case SA_GW:
        {
          ip_addr ip = v1.val.ip;
-         struct iface *ifa = ipa_is_link_local(ip) ? rta->nh.iface : NULL;
-         neighbor *n = neigh_find((*fs->rte)->src->proto, ip, ifa, 0);
+         struct iface *ifa = ipa_is_link_local(ip) || (rta->nh.flags & RNF_ONLINK) ? rta->nh.iface : NULL;
+         neighbor *n = neigh_find((*fs->rte)->src->proto, ip, ifa, (rta->nh.flags & RNF_ONLINK) ? NEF_ONLINK : 0);
          if (!n || (n->scope == SCOPE_HOST))
            runtime( "Invalid gw address" );
 
@@ -801,6 +802,15 @@
        rta->pref = v1.val.i;
        break;
 
+      case SA_ONLINK:
+       {
+         if (v1.val.i)
+           rta->nh.flags |= RNF_ONLINK;
+         else
+           rta->nh.flags &= ~RNF_ONLINK;
+       }
+       break;
+
       default:
        bug("Invalid static attribute access (%u/%u)", sa.f_type, sa.sa_code);
       }