From bd5868794c6dd936127424873eb1fc1521b2b7c2 Mon Sep 17 00:00:00 2001
From: Yutaro Hayakawa <yutaro.hayakawa@isovalent.com>
Date: Wed, 5 Jul 2023 12:56:08 +0900
Subject: [PATCH] Support fibmatch flag for RouteGetWithOptions

Support `ip route get fibmatch` equivalent with RouteGetWithOptions by
adding FIBMatch flag to RouteGetOptions.

Signed-off-by: Yutaro Hayakawa <yutaro.hayakawa@isovalent.com>
---
 route_linux.go | 16 +++++++++-----
 route_test.go  | 59 ++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 69 insertions(+), 6 deletions(-)

diff --git a/route_linux.go b/route_linux.go
index b1ef181..aacc44c 100644
--- a/route_linux.go
+++ b/route_linux.go
@@ -1320,12 +1320,13 @@ func deserializeRoute(m []byte) (Route, error) {
 // RouteGetOptions contains a set of options to use with
 // RouteGetWithOptions
 type RouteGetOptions struct {
-	Iif     string
-	Oif     string
-	VrfName string
-	SrcAddr net.IP
-	UID     *uint32
-	Mark    int
+	Iif      string
+	Oif      string
+	VrfName  string
+	SrcAddr  net.IP
+	UID      *uint32
+	Mark     int
+	FIBMatch bool
 }
 
 // RouteGetWithOptions gets a route to a specific destination from the host system.
@@ -1361,6 +1362,9 @@ func (h *Handle) RouteGetWithOptions(destination net.IP, options *RouteGetOption
 		msg.Src_len = bitlen
 	}
 	msg.Flags = unix.RTM_F_LOOKUP_TABLE
+	if options != nil && options.FIBMatch {
+		msg.Flags |= unix.RTM_F_FIB_MATCH
+	}
 	req.AddData(msg)
 
 	rtaDst := nl.NewRtAttr(unix.RTA_DST, destinationData)
diff --git a/route_test.go b/route_test.go
index 2eb6891..d4d584f 100644
--- a/route_test.go
+++ b/route_test.go
@@ -2019,3 +2019,62 @@ func TestRouteFWMarkOption(t *testing.T) {
 		t.Fatal(routes)
 	}
 }
+
+func TestRouteGetFIBMatchOption(t *testing.T) {
+	tearDown := setUpNetlinkTest(t)
+	defer tearDown()
+
+	err := LinkAdd(&Dummy{LinkAttrs{Name: "eth0"}})
+	if err != nil {
+		t.Fatal(err)
+	}
+	link, err := LinkByName("eth0")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err = LinkSetUp(link); err != nil {
+		t.Fatal(err)
+	}
+	addr := &Addr{
+		IPNet: &net.IPNet{
+			IP:   net.IPv4(192, 168, 0, 2),
+			Mask: net.CIDRMask(24, 32),
+		},
+	}
+	if err = AddrAdd(link, addr); err != nil {
+		t.Fatal(err)
+	}
+
+	route := &Route{
+		LinkIndex: link.Attrs().Index,
+		Gw:        net.IPv4(192, 168, 1, 1),
+		Dst: &net.IPNet{
+			IP:   net.IPv4(192, 168, 2, 0),
+			Mask: net.CIDRMask(24, 32),
+		},
+		Flags: int(FLAG_ONLINK),
+	}
+
+	err = RouteAdd(route)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	routes, err := RouteGetWithOptions(net.IPv4(192, 168, 2, 1), &RouteGetOptions{FIBMatch: true})
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if len(routes) != 1 {
+		t.Fatalf("More than one route matched %v", routes)
+	}
+
+	if len(routes[0].ListFlags()) != 1 {
+		t.Fatalf("More than one route flag returned %v", routes[0].ListFlags())
+	}
+
+	flag := routes[0].ListFlags()[0]
+	if flag != "onlink" {
+		t.Fatalf("Unexpected flag %s returned", flag)
+	}
+}