From c3335b504403136ef8deb81cb034480a65ca2815 Mon Sep 17 00:00:00 2001
From: Ondrej Zajicek <santiago@crfreenet.org>
Date: Fri, 16 Feb 2024 18:44:40 +0100
Subject: [PATCH] Static: Allow to define both nexthop and interface

Allow to define both nexthop and interface using iproute2-like syntax,
e.g.: route 10.0.0.0/16 via 10.1.0.1 dev "eth0";

Now we can avoid to use link-local scope hack (e.g. 10.1.0.1%eth0)
for cases where both nexthop and interface have to be defined.

Thanks to Marcin Saklak for the suggestion.
---
 doc/bird.sgml         | 12 ++++++++++--
 proto/static/config.Y |  3 +++
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/doc/bird.sgml b/doc/bird.sgml
index 3861a595..76ca7f75 100644
--- a/doc/bird.sgml
+++ b/doc/bird.sgml
@@ -5940,6 +5940,12 @@ options (<cf/bfd/ and <cf/weight 1/), the second nexthop has just <cf/weight 2/.
 	that BFD protocol also has to be configured, see <ref id="bfd" name="BFD">
 	section for details. Default value is no.
 
+	<tag><label id="static-route-dev">dev <m/text/</tag>
+	The outgoing interface associated with the nexthop. Useful for
+	link-local nexthop addresses or when multiple interfaces use the same
+	network prefix. By default, the outgoing interface is resolved from the
+	nexthop address.
+
 	<tag><label id="static-route-mpls">mpls <m/num/[/<m/num/[/<m/num/[...]]]</tag>
 	MPLS labels that should be pushed to packets forwarded by the route.
 	The option could be used for both IP routes (on MPLS ingress routers)
@@ -6120,7 +6126,8 @@ protocol static {
 		via 198.51.100.20 bfd	# BFD-controlled next hop
 		via 192.0.2.1;
 	route 203.0.113.0/24 blackhole; # Sink route
-	route 10.2.0.0/24 via "arc0";	# Secondary network
+	route 10.2.0.0/24 via "arc0";	# Direct route
+	route 10.2.2.0/24 via 192.0.2.1 dev "eth0" onlink; # Route with both nexthop and iface
 	route 192.168.10.0/24 via 198.51.100.100 {
 		ospf_metric1 = 20;	# Set extended attribute
 	};
@@ -6139,7 +6146,8 @@ protocol static {
 	route 2001:db8:10::/48 via 2001:db8:1::1;	# Route with global nexthop
 	route 2001:db8:20::/48 via fe80::10%eth0;	# Route with link-local nexthop
 	route 2001:db8:30::/48 via fe80::20%'eth1.60';	# Iface with non-alphanumeric characters
-	route 2001:db8:40::/48 via "eth2";		# Direct route to eth2
+	route 2001:db8:40::/48 via fe80::30 dev "eth1";	# Another link-local nexthop
+	route 2001:db8:50::/48 via "eth2";		# Direct route to eth2
 	route 2001:db8::/32 unreachable;		# Unreachable route
 	route ::/0 via 2001:db8:1::1 bfd;		# BFD-controlled default route
 }
diff --git a/proto/static/config.Y b/proto/static/config.Y
index 215681e8..e746b63c 100644
--- a/proto/static/config.Y
+++ b/proto/static/config.Y
@@ -87,6 +87,9 @@ stat_nexthop:
       this_snh->via = IPA_NONE;
       this_snh->iface = if_get_by_name($2);
     }
+  | stat_nexthop DEV TEXT {
+      this_snh->iface = if_get_by_name($3);
+    }
   | stat_nexthop MPLS label_stack {
     this_snh->mls = $3;
   }