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

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

2 files changed, 251 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
+}
diff --git a/table/message_test.go b/table/message_test.go
new file mode 100644
index 00000000..ce29d899
--- /dev/null
+++ b/table/message_test.go
@@ -0,0 +1,142 @@
+// 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"
+	"github.com/stretchr/testify/assert"
+	"reflect"
+	"testing"
+)
+
+func updateMsg1(as []uint16) *bgp.BGPMessage {
+	origin := bgp.NewPathAttributeOrigin(0)
+	aspathParam := []bgp.AsPathParamInterface{bgp.NewAsPathParam(2, as)}
+	aspath := bgp.NewPathAttributeAsPath(aspathParam)
+	nexthop := bgp.NewPathAttributeNextHop("192.168.50.1")
+	med := bgp.NewPathAttributeMultiExitDisc(0)
+
+	pathAttributes := []bgp.PathAttributeInterface{
+		origin,
+		aspath,
+		nexthop,
+		med,
+	}
+
+	nlri := []bgp.NLRInfo{*bgp.NewNLRInfo(24, "10.10.10.0")}
+	return bgp.NewBGPUpdateMessage([]bgp.WithdrawnRoute{}, pathAttributes, nlri)
+}
+
+func TestAs4PathNonAsTrans(t *testing.T) {
+	as := []uint16{65000, 4000, 40001}
+	m := updateMsg1(as).Body.(*bgp.BGPUpdate)
+	originalAsPath := m.PathAttributes[1]
+	UpdatePathAttrs4ByteAs(m)
+	assert.Equal(t, reflect.TypeOf(m.PathAttributes[0]).String(), "*bgp.PathAttributeOrigin")
+	assert.Equal(t, reflect.TypeOf(m.PathAttributes[1]).String(), "*bgp.PathAttributeAsPath")
+	assert.Equal(t, reflect.TypeOf(m.PathAttributes[2]).String(), "*bgp.PathAttributeNextHop")
+	assert.Equal(t, reflect.TypeOf(m.PathAttributes[3]).String(), "*bgp.PathAttributeMultiExitDisc")
+
+	asAttr := m.PathAttributes[1].(*bgp.PathAttributeAsPath)
+	assert.Equal(t, len(asAttr.Value), 1)
+	for _, param := range asAttr.Value {
+		asParam := param.(*bgp.As4PathParam)
+		for i, v := range asParam.AS {
+			assert.Equal(t, v, as[i])
+		}
+	}
+	UpdatePathAttrs2ByteAs(m)
+	assert.Equal(t, m.PathAttributes[1], originalAsPath)
+}
+
+func TestAsPathAsTrans(t *testing.T) {
+	as := []uint16{65000, 4000, bgp.AS_TRANS, bgp.AS_TRANS, 40001}
+	m := updateMsg1(as).Body.(*bgp.BGPUpdate)
+
+	m.PathAttributes = append(m.PathAttributes, m.PathAttributes[3])
+	as4 := []uint32{400000, 300000}
+	aspathParam := []*bgp.As4PathParam{bgp.NewAs4PathParam(2, as4)}
+	m.PathAttributes[3] = bgp.NewPathAttributeAs4Path(aspathParam)
+	assert.Equal(t, len(m.PathAttributes), 5)
+
+	originalAsPath := m.PathAttributes[1]
+	originalAs4Path := m.PathAttributes[3]
+	UpdatePathAttrs4ByteAs(m)
+	assert.Equal(t, len(m.PathAttributes), 4)
+
+	assert.Equal(t, reflect.TypeOf(m.PathAttributes[0]).String(), "*bgp.PathAttributeOrigin")
+	assert.Equal(t, reflect.TypeOf(m.PathAttributes[1]).String(), "*bgp.PathAttributeAsPath")
+	assert.Equal(t, reflect.TypeOf(m.PathAttributes[2]).String(), "*bgp.PathAttributeNextHop")
+	assert.Equal(t, reflect.TypeOf(m.PathAttributes[3]).String(), "*bgp.PathAttributeMultiExitDisc")
+
+	newAS := []uint32{65000, 4000, 400000, 300000, 40001}
+	asAttr := m.PathAttributes[1].(*bgp.PathAttributeAsPath)
+	assert.Equal(t, len(asAttr.Value), 1)
+	for _, param := range asAttr.Value {
+		asParam := param.(*bgp.As4PathParam)
+		for i, v := range asParam.AS {
+			assert.Equal(t, v, newAS[i])
+		}
+	}
+	UpdatePathAttrs2ByteAs(m)
+	assert.Equal(t, len(m.PathAttributes), 5)
+	assert.Equal(t, m.PathAttributes[1], originalAsPath)
+	assert.Equal(t, m.PathAttributes[4], originalAs4Path)
+}
+
+func TestAs4PathUnchanged(t *testing.T) {
+	as4 := []uint32{65000, 4000, 500000, 400010}
+	m := updateMsg1([]uint16{}).Body.(*bgp.BGPUpdate)
+	aspathParam := []bgp.AsPathParamInterface{bgp.NewAs4PathParam(2, as4)}
+	m.PathAttributes[1] = bgp.NewPathAttributeAsPath(aspathParam)
+	UpdatePathAttrs4ByteAs(m)
+	assert.Equal(t, len(m.PathAttributes), 4)
+
+	assert.Equal(t, reflect.TypeOf(m.PathAttributes[0]).String(), "*bgp.PathAttributeOrigin")
+	assert.Equal(t, reflect.TypeOf(m.PathAttributes[1]).String(), "*bgp.PathAttributeAsPath")
+	assert.Equal(t, reflect.TypeOf(m.PathAttributes[2]).String(), "*bgp.PathAttributeNextHop")
+	assert.Equal(t, reflect.TypeOf(m.PathAttributes[3]).String(), "*bgp.PathAttributeMultiExitDisc")
+
+	asAttr := m.PathAttributes[1].(*bgp.PathAttributeAsPath)
+	assert.Equal(t, len(asAttr.Value), 1)
+	for _, param := range asAttr.Value {
+		asParam := param.(*bgp.As4PathParam)
+		for i, v := range asParam.AS {
+			assert.Equal(t, v, as4[i])
+		}
+	}
+}
+
+func TestAsPathUnchanged(t *testing.T) {
+	as := []uint16{65000, 4000, 5000, 4001}
+	m := updateMsg1(as).Body.(*bgp.BGPUpdate)
+	UpdatePathAttrs2ByteAs(m)
+	assert.Equal(t, len(m.PathAttributes), 4)
+
+	assert.Equal(t, reflect.TypeOf(m.PathAttributes[0]).String(), "*bgp.PathAttributeOrigin")
+	assert.Equal(t, reflect.TypeOf(m.PathAttributes[1]).String(), "*bgp.PathAttributeAsPath")
+	assert.Equal(t, reflect.TypeOf(m.PathAttributes[2]).String(), "*bgp.PathAttributeNextHop")
+	assert.Equal(t, reflect.TypeOf(m.PathAttributes[3]).String(), "*bgp.PathAttributeMultiExitDisc")
+
+	asAttr := m.PathAttributes[1].(*bgp.PathAttributeAsPath)
+	assert.Equal(t, len(asAttr.Value), 1)
+	for _, param := range asAttr.Value {
+		asParam := param.(*bgp.AsPathParam)
+		for i, v := range asParam.AS {
+			assert.Equal(t, v, as[i])
+		}
+	}
+}