From 391cc95300b4ec55f185d9e5fd60b4152f9df268 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Maxime=20Soul=C3=A9?= <btik-git@scoubidou.com>
Date: Mon, 26 Feb 2024 17:07:32 +0100
Subject: [PATCH] Add RouteChange API
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Signed-off-by: Maxime Soulé <btik-git@scoubidou.com>
---
 handle_unspecified.go  |  4 +++
 netlink_unspecified.go |  4 +++
 route_linux.go         | 15 ++++++++++
 route_test.go          | 67 +++++++++++++++++++++++++++++++++++++++++-
 4 files changed, 89 insertions(+), 1 deletion(-)

diff --git a/handle_unspecified.go b/handle_unspecified.go
index d0966680..3fe03642 100644
--- a/handle_unspecified.go
+++ b/handle_unspecified.go
@@ -263,6 +263,10 @@ func (h *Handle) RouteAppend(route *Route) error {
 	return ErrNotImplemented
 }
 
+func (h *Handle) RouteChange(route *Route) error {
+	return ErrNotImplemented
+}
+
 func (h *Handle) RouteDel(route *Route) error {
 	return ErrNotImplemented
 }
diff --git a/netlink_unspecified.go b/netlink_unspecified.go
index adac048f..0f6fde25 100644
--- a/netlink_unspecified.go
+++ b/netlink_unspecified.go
@@ -204,6 +204,10 @@ func RouteAppend(route *Route) error {
 	return ErrNotImplemented
 }
 
+func RouteChange(route *Route) error {
+	return ErrNotImplemented
+}
+
 func RouteDel(route *Route) error {
 	return ErrNotImplemented
 }
diff --git a/route_linux.go b/route_linux.go
index 99467df3..8c274414 100644
--- a/route_linux.go
+++ b/route_linux.go
@@ -790,6 +790,21 @@ func (h *Handle) RouteAddEcmp(route *Route) error {
 	return err
 }
 
+// RouteChange will add a route to the system.
+// Equivalent to: `ip route change $route`
+func RouteChange(route *Route) error {
+	return pkgHandle.RouteChange(route)
+}
+
+// RouteChange will add a route to the system.
+// Equivalent to: `ip route change $route`
+func (h *Handle) RouteChange(route *Route) error {
+	flags := unix.NLM_F_REPLACE | unix.NLM_F_ACK
+	req := h.newNetlinkRequest(unix.RTM_NEWROUTE, flags)
+	_, err := h.routeHandle(route, req, nl.NewRtMsg())
+	return err
+}
+
 // RouteReplace will add a route to the system.
 // Equivalent to: `ip route replace $route`
 func RouteReplace(route *Route) error {
diff --git a/route_test.go b/route_test.go
index a862bbb5..67497e24 100644
--- a/route_test.go
+++ b/route_test.go
@@ -331,6 +331,72 @@ func TestRoute6AddDel(t *testing.T) {
 	}
 }
 
+func TestRouteChange(t *testing.T) {
+	tearDown := setUpNetlinkTest(t)
+	defer tearDown()
+
+	// get loopback interface
+	link, err := LinkByName("lo")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// bring the interface up
+	if err := LinkSetUp(link); err != nil {
+		t.Fatal(err)
+	}
+
+	// add a gateway route
+	dst := &net.IPNet{
+		IP:   net.IPv4(192, 168, 0, 0),
+		Mask: net.CIDRMask(24, 32),
+	}
+
+	ip := net.IPv4(127, 1, 1, 1)
+	route := Route{LinkIndex: link.Attrs().Index, Dst: dst, Src: ip}
+
+	if err := RouteChange(&route); err == nil {
+		t.Fatal("Route added while it should fail")
+	}
+
+	if err := RouteAdd(&route); err != nil {
+		t.Fatal(err)
+	}
+	routes, err := RouteList(link, FAMILY_V4)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(routes) != 1 {
+		t.Fatal("Route not added properly")
+	}
+
+	ip = net.IPv4(127, 1, 1, 2)
+	route = Route{LinkIndex: link.Attrs().Index, Dst: dst, Src: ip}
+	if err := RouteChange(&route); err != nil {
+		t.Fatal(err)
+	}
+
+	routes, err = RouteList(link, FAMILY_V4)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if len(routes) != 1 || !routes[0].Src.Equal(ip) {
+		t.Fatal("Route not changed properly")
+	}
+
+	if err := RouteDel(&route); err != nil {
+		t.Fatal(err)
+	}
+	routes, err = RouteList(link, FAMILY_V4)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(routes) != 0 {
+		t.Fatal("Route not removed properly")
+	}
+}
+
 func TestRouteReplace(t *testing.T) {
 	tearDown := setUpNetlinkTest(t)
 	defer tearDown()
@@ -390,7 +456,6 @@ func TestRouteReplace(t *testing.T) {
 	if len(routes) != 0 {
 		t.Fatal("Route not removed properly")
 	}
-
 }
 
 func TestRouteAppend(t *testing.T) {