From f2d8e6801e88a84b1e57da72d078d7569598a5f5 Mon Sep 17 00:00:00 2001
From: "Ondrej Zajicek (work)" <santiago@crfreenet.org>
Date: Mon, 5 Nov 2018 22:03:21 +0100
Subject: [PATCH] Filter: Make ifname attribute modifiable

Allow to change an interface associated with a route by setting
ifname attribute. It will also change the route to a direct one.
---
 doc/bird.sgml   |  3 ++-
 filter/config.Y |  2 +-
 filter/filter.c | 14 ++++++++++++++
 nest/iface.c    |  7 ++++---
 4 files changed, 21 insertions(+), 5 deletions(-)

diff --git a/doc/bird.sgml b/doc/bird.sgml
index fdfae2a6..72c386f2 100644
--- a/doc/bird.sgml
+++ b/doc/bird.sgml
@@ -1606,7 +1606,8 @@ regarded as empty bgppath/*clist for most purposes.
 	<tag><label id="rta-ifname"><m/string/ ifname</tag>
 	Name of the outgoing interface. Sink routes (like blackhole, unreachable
 	or prohibit) and multipath routes have no interface associated with
-	them, so <cf/ifname/ returns an empty string for such routes. Read-only.
+	them, so <cf/ifname/ returns an empty string for such routes. Setting it
+	would also change route to a direct one (remove gateway).
 
 	<tag><label id="rta-ifindex"><m/int/ ifindex</tag>
 	Index of the outgoing interface. System wide index of the interface. May
diff --git a/filter/config.Y b/filter/config.Y
index 93ad8d8b..d865d11f 100644
--- a/filter/config.Y
+++ b/filter/config.Y
@@ -852,7 +852,7 @@ static_attr:
  | SOURCE  { $$ = f_new_static_attr(T_ENUM_RTS,   SA_SOURCE,	0); }
  | SCOPE   { $$ = f_new_static_attr(T_ENUM_SCOPE, SA_SCOPE,	1); }
  | DEST    { $$ = f_new_static_attr(T_ENUM_RTD,   SA_DEST,	1); }
- | IFNAME  { $$ = f_new_static_attr(T_STRING,     SA_IFNAME,	0); }
+ | IFNAME  { $$ = f_new_static_attr(T_STRING,     SA_IFNAME,	1); }
  | IFINDEX { $$ = f_new_static_attr(T_INT,        SA_IFINDEX,	0); }
  ;
 
diff --git a/filter/filter.c b/filter/filter.c
index edf54ec0..f308e7fd 100644
--- a/filter/filter.c
+++ b/filter/filter.c
@@ -1002,6 +1002,20 @@ interpret(struct f_inst *what)
 	rta->hostentry = NULL;
 	break;
 
+      case SA_IFNAME:
+	{
+	  struct iface *ifa = if_find_by_name(v1.val.s);
+	  if (!ifa)
+	    runtime( "Invalid iface name" );
+
+	  rta->dest = RTD_UNICAST;
+	  rta->nh.gw = IPA_NONE;
+	  rta->nh.iface = ifa;
+	  rta->nh.next = NULL;
+	  rta->hostentry = NULL;
+	}
+	break;
+
       default:
 	bug("Invalid static attribute access (%x)", res.type);
       }
diff --git a/nest/iface.c b/nest/iface.c
index 9462b634..23a82ac5 100644
--- a/nest/iface.c
+++ b/nest/iface.c
@@ -449,7 +449,7 @@ if_find_by_name(char *name)
   struct iface *i;
 
   WALK_LIST(i, iface_list)
-    if (!strcmp(i->name, name))
+    if (!strcmp(i->name, name) && !(i->flags & IF_SHUTDOWN))
       return i;
   return NULL;
 }
@@ -459,8 +459,9 @@ if_get_by_name(char *name)
 {
   struct iface *i;
 
-  if (i = if_find_by_name(name))
-    return i;
+  WALK_LIST(i, iface_list)
+    if (!strcmp(i->name, name))
+      return i;
 
   /* No active iface, create a dummy */
   i = mb_allocz(if_pool, sizeof(struct iface));