From 75faf5bb77706267feb0438803c2b318130c9916 Mon Sep 17 00:00:00 2001
From: Lubomir Rintel <lkundrak@v3.sk>
Date: Thu, 16 Mar 2017 13:55:14 +0000
Subject: [PATCH] route-manager: add routine to query route shadowing for a
 link

If a route is shadowed by another route to the same network it's a good
indication we're multihoming and want to disable the Strict RP filtering.
---
 src/nm-route-manager.c | 27 +++++++++++++++++++++++++++
 src/nm-route-manager.h |  1 +
 2 files changed, 28 insertions(+)

diff --git a/src/nm-route-manager.c b/src/nm-route-manager.c
index a8778e2a7d..13cb032724 100644
--- a/src/nm-route-manager.c
+++ b/src/nm-route-manager.c
@@ -967,6 +967,33 @@ nm_route_manager_route_flush (NMRouteManager *self, int ifindex)
 	return success;
 }
 
+/**
+ * nm_route_manager_ip4_routes_shadowed:
+ * @ifindex: Interface index
+ *
+ * Returns: %TRUE if some other link has a route to the same destination
+ *   with a lower metric.
+ */
+gboolean
+nm_route_manager_ip4_routes_shadowed (NMRouteManager *self, int ifindex)
+{
+	NMRouteManagerPrivate *priv = NM_ROUTE_MANAGER_GET_PRIVATE (self);
+	RouteIndex *index = priv->ip4_routes.index;
+	const NMPlatformIP4Route *route;
+	guint i;
+
+	for (i = 1; i < index->len; i++) {
+		route = (const NMPlatformIP4Route *) index->entries[i];
+
+		if (route->ifindex != ifindex)
+			continue;
+		if (_v4_route_dest_cmp (route, (const NMPlatformIP4Route *) index->entries[i - 1]) == 0)
+			return TRUE;
+	}
+
+	return FALSE;
+}
+
 /*****************************************************************************/
 
 static gboolean
diff --git a/src/nm-route-manager.h b/src/nm-route-manager.h
index d12f025603..181d794ee5 100644
--- a/src/nm-route-manager.h
+++ b/src/nm-route-manager.h
@@ -38,6 +38,7 @@ gboolean nm_route_manager_ip4_route_sync (NMRouteManager *self, int ifindex, con
 gboolean nm_route_manager_ip6_route_sync (NMRouteManager *self, int ifindex, const GArray *known_routes, gboolean ignore_kernel_routes, gboolean full_sync);
 gboolean nm_route_manager_route_flush (NMRouteManager *self, int ifindex);
 
+gboolean nm_route_manager_ip4_routes_shadowed (NMRouteManager *self, int ifindex);
 void nm_route_manager_ip4_route_register_device_route_purge_list (NMRouteManager *self, GArray *device_route_purge_list);
 
 NMRouteManager *nm_route_manager_get (void);