table: add helper functions to modify PathAttributes for 4 and 2 byte AS.

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

1 files changed, 109 insertions, 0 deletions

diff --git a/table/message.go b/table/message.go
new file mode 100644
index 00000000..35eb501a
--- /dev/null
+++ b/table/message.go
@@ -0,0 +1,109 @@
+// Copyright (C) 2014 Nippon Telegraph and Telephone Corporation.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+// implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package table
+
+import (
+	"github.com/osrg/gobgp/packet"
+)
+
+func UpdatePathAttrs2ByteAs(msg *bgp.BGPUpdate) error {
+	var asAttr *bgp.PathAttributeAsPath
+	for _, attr := range msg.PathAttributes {
+		switch attr.(type) {
+		case *bgp.PathAttributeAsPath:
+			asAttr = attr.(*bgp.PathAttributeAsPath)
+		}
+	}
+
+	as4pathParam := make([]*bgp.As4PathParam, 0)
+	for i, param := range asAttr.Value {
+		asParam, y := param.(*bgp.As4PathParam)
+		if !y {
+			continue
+		}
+
+		newAs := make([]uint32, 0)
+		oldAs := make([]uint16, len(asParam.AS))
+		for j := 0; j < len(asParam.AS); j++ {
+			if asParam.AS[j] > (1<<16)-1 {
+				oldAs[j] = bgp.AS_TRANS
+				newAs = append(newAs, asParam.AS[j])
+			} else {
+				oldAs[j] = uint16(asParam.AS[j])
+			}
+		}
+		asAttr.Value[i] = bgp.NewAsPathParam(asParam.Type, oldAs)
+		if len(newAs) > 0 {
+			as4pathParam = append(as4pathParam, bgp.NewAs4PathParam(asParam.Type, newAs))
+		}
+	}
+	if len(as4pathParam) > 0 {
+		msg.PathAttributes = append(msg.PathAttributes, bgp.NewPathAttributeAs4Path(as4pathParam))
+	}
+	return nil
+}
+
+func UpdatePathAttrs4ByteAs(msg *bgp.BGPUpdate) error {
+	newPathAttrs := make([]bgp.PathAttributeInterface, 0)
+	var asAttr *bgp.PathAttributeAsPath
+	var as4Attr *bgp.PathAttributeAs4Path
+
+	for _, attr := range msg.PathAttributes {
+		switch attr.(type) {
+		case *bgp.PathAttributeAsPath:
+			asAttr = attr.(*bgp.PathAttributeAsPath)
+			newPathAttrs = append(newPathAttrs, attr)
+		case *bgp.PathAttributeAs4Path:
+			as4Attr = attr.(*bgp.PathAttributeAs4Path)
+		default:
+			newPathAttrs = append(newPathAttrs, attr)
+		}
+	}
+
+	AS := make([]uint32, 0)
+	if as4Attr != nil {
+		for _, p := range as4Attr.Value {
+			AS = append(AS, p.AS...)
+		}
+		msg.PathAttributes = newPathAttrs
+	}
+
+	transIdx := 0
+	for i, param := range asAttr.Value {
+		asParam, y := param.(*bgp.AsPathParam)
+		if !y {
+			continue
+		}
+
+		newAS := make([]uint32, len(asParam.AS))
+		for j := 0; j < len(asParam.AS); j++ {
+			if asParam.AS[j] == bgp.AS_TRANS {
+				if transIdx == len(AS) {
+					//return error
+				}
+				newAS[j] = AS[transIdx]
+				transIdx++
+			} else {
+				newAS[j] = uint32(asParam.AS[j])
+			}
+		}
+		asAttr.Value[i] = bgp.NewAs4PathParam(asParam.Type, newAS)
+	}
+	if len(AS) != transIdx {
+		//return error
+	}
+	return nil
+}