table: implement Clone() to copy pathattributes in Path struct

In some cases, we need to modify pathattributes in Path and creates an
update message based on it. Clone() is used to avoid chaning the
pathattributes in the table.

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>

2 files changed, 45 insertions, 19 deletions

diff --git a/table/path.go b/table/path.go
index e7536f22..846c7e16 100644
--- a/table/path.go
+++ b/table/path.go
@@ -18,7 +18,6 @@ package table
 import (
 	"fmt"
 	"github.com/osrg/gobgp/packet"
-	//"github.com/osrg/gobgp/utils"
 	"net"
 	"reflect"
 )
@@ -27,7 +26,6 @@ type Path interface {
 	String() string
 	GetPathAttrs() []bgp.PathAttributeInterface
 	GetPathAttr(int) (int, bgp.PathAttributeInterface)
-	//	clone(forWithdrawal bool) Path
 	getRouteFamily() RouteFamily
 	setSource(source *PeerInfo)
 	getSource() *PeerInfo
@@ -41,6 +39,7 @@ type Path interface {
 	getPrefix() net.IP
 	setMedSetByTargetNeighbor(medSetByTargetNeighbor bool)
 	getMedSetByTargetNeighbor() bool
+	Clone() Path
 }
 
 type PathDefault struct {
@@ -74,6 +73,18 @@ func NewPathDefault(rf RouteFamily, source *PeerInfo, nlri bgp.AddrPrefixInterfa
 	return path
 }
 
+// create new PathAttributes
+func (pd *PathDefault) Clone() Path {
+	copiedAttrs := append([]bgp.PathAttributeInterface(nil), pd.pathAttrs...)
+	for i, attr := range copiedAttrs {
+		t, v := reflect.TypeOf(attr), reflect.ValueOf(attr)
+		newAttrObjp := reflect.New(t.Elem())
+		newAttrObjp.Elem().Set(v.Elem())
+		copiedAttrs[i] = newAttrObjp.Interface().(bgp.PathAttributeInterface)
+	}
+	return CreatePath(pd.source, pd.nlri, copiedAttrs, pd.withdraw)
+}
+
 func (pd *PathDefault) getRouteFamily() RouteFamily {
 	return pd.routeFamily
 }
@@ -152,23 +163,6 @@ func (pd *PathDefault) GetPathAttr(pattrType int) (int, bgp.PathAttributeInterfa
 	return -1, nil
 }
 
-// func (pi *PathDefault) clone(forWithdrawal bool) Path {
-// 	pathAttrs := utils.NewOrderedMap()
-// 	if !forWithdrawal {
-// 		pathAttrs = pi.getPathAttributeMap()
-// 	}
-// 	def := NewPathDefault(pi.getRouteFamily(), pi.getSource(), pi.GetNlri(), pi.getSourceVerNum(),
-// 		pi.getNexthop(), forWithdrawal, pathAttrs, pi.getMedSetByTargetNeighbor())
-// 	switch pi.getRouteFamily() {
-// 	case RF_IPv4_UC:
-// 		return &IPv4Path{PathDefault: def}
-// 	case RF_IPv6_UC:
-// 		return &IPv6Path{PathDefault: def}
-// 	default:
-// 		return def
-// 	}
-//}
-
 // return Path's string representation
 func (pi *PathDefault) String() string {
 	str := fmt.Sprintf("IPv4Path Source: %d, ", pi.getSourceVerNum())
diff --git a/table/table_manager_test.go b/table/table_manager_test.go
index c0abcd84..c9d6e22a 100644
--- a/table/table_manager_test.go
+++ b/table/table_manager_test.go
@@ -2239,6 +2239,38 @@ func TestProcessBGPUpdate_multiple_nlri_ipv6(t *testing.T) {
 
 }
 
+func TestModifyPathAttribute(t *testing.T) {
+	tm := NewTableManager()
+
+	bgpMessage := update_fromR1()
+	peer := peerR1()
+	pList, wList, err := tm.ProcessUpdate(peer, bgpMessage)
+	assert.Equal(t, len(pList), 1)
+	assert.Equal(t, len(wList), 0)
+	assert.NoError(t, err)
+
+	path0 := pList[0]
+	path1 := path0.Clone()
+
+	_, attr1 := path1.GetPathAttr(bgp.BGP_ATTR_TYPE_MULTI_EXIT_DISC)
+	mx1 := attr1.(*bgp.PathAttributeMultiExitDisc)
+	original := mx1.Value
+	mx1.Value++
+
+	table := tm.Tables[RF_IPv4_UC]
+	dest := table.getDestination(table.tableKey(path0.GetNlri()).String()).(*IPv4Destination)
+	path2 := dest.getKnownPathList()
+	_, attr2 := path2[0].GetPathAttr(bgp.BGP_ATTR_TYPE_MULTI_EXIT_DISC)
+	mx2 := attr2.(*bgp.PathAttributeMultiExitDisc)
+	assert.Equal(t, original, mx2.Value)
+
+	path3 := path0
+	_, attr3 := path3.GetPathAttr(bgp.BGP_ATTR_TYPE_MULTI_EXIT_DISC)
+	mx3 := attr3.(*bgp.PathAttributeMultiExitDisc)
+	mx3.Value++
+	assert.Equal(t, mx2.Value, mx3.Value)
+}
+
 func update_fromR1() *bgp.BGPMessage {
 
 	origin := bgp.NewPathAttributeOrigin(0)