Adding support for empty AS paths

protocols/bgp/packet/path_attributes.go

@@ -452,6 +452,10 @@ func ParseASPathStr(asPathString string) (*PathAttribute, error) {
 	newSegmentNeeded := true
 	currentSegment := -1
 	for _, asn := range strings.Split(asPathString, " ") {
+		if asn == "" {
+			continue
+		}
+
 		if isBeginOfASSet(asn) {
 			currentType = ASSet
 			newSegmentNeeded = true

protocols/bgp/packet/path_attributes_test.go

@@ -1298,6 +1298,15 @@ func TestParseASPathStr(t *testing.T) {
 		wantFail bool
 		expected *PathAttribute
 	}{
+		{
+			name:     "Empty AS Path",
+			input:    "",
+			wantFail: false,
+			expected: &PathAttribute{
+				TypeCode: ASPathAttr,
+				Value:    ASPath{},
+			},
+		},
 		{
 			name:     "Simple AS_SEQUENCE",
 			input:    "3320 15169",

protocols/bgp/server/update_sender_add_path.go

@@ -41,6 +41,10 @@ func (u *UpdateSenderAddPath) AddPath(pfx net.Prefix, p *route.Path) error {
 				Next: &packet.PathAttribute{
 					TypeCode: packet.NextHopAttr,
 					Value:    p.BGPPath.NextHop,
+					Next: &packet.PathAttribute{
+						TypeCode: packet.LocalPrefAttr,
+						Value:    p.BGPPath.LocalPref,
+					},
 				},
 			},
 		},