go-bgp

commit b279623885dd86032d8478f50aa68dd50a36b2f7
parent 45d38afd3229304a1d6893ed350bd33edb47f7ce
Author: atomic <atomic@2f30.org>
Date:   Tue, 17 Feb 2015 06:54:29 +0100

added general structure of the bgp message parser

Diffstat:
A
bgp/bgp.go
 | 
134
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
A
bgp/bgp_test.go
 | 
9
+++++++++

2 files changed, 143 insertions(+), 0 deletions(-)
diff --git a/bgp/bgp.go b/bgp/bgp.go
@@ -0,0 +1,134 @@
+package bgp
+
+import (
+	"bytes"
+	"encoding/binary"
+	"fmt"
+	"io/ioutil"
+)
+
+type uint128 struct {
+	H uint64
+	L uint64
+}
+
+// magic numbers explained
+const (
+	MinMsgLen       = 19
+	MinNotifiMsgLen = 21
+)
+
+// bgp msg types
+const (
+	_ = iota
+	OPEN
+	UPDATE
+	NOTIFICATION
+	KEEPALIVE
+)
+
+type BgpHdr struct {
+	Marker uint128
+	Len    uint16
+	Type   uint8
+}
+
+type BgpMsg struct {
+	h BgpHdr
+}
+
+type BgpOpenMsg struct {
+	Hdr    BgpHdr
+	Ver    uint8
+	MyAs   uint16
+	Htime  uint16
+	BgpId  uint32
+	OptLen uint8
+	Opt    []byte
+}
+
+type BgpUpdateMsg struct {
+	Hdr               BgpHdr
+	UnfRoutesLen      uint16
+	WithdRoutes       []byte
+	TotalPathAttrLen  uint16
+	NetLayerReachInfo []byte
+}
+type BgpNotifiMsg struct {
+	Hdr        BgpHdr
+	ErrCode    uint8
+	ErrSubCode uint8
+	Data       []byte
+}
+
+type BgpKeepaliveMsg struct {
+	Hdr BgpHdr
+}
+
+func parse(b []byte) (interface{}, error) {
+	var h BgpHdr
+
+	// parse header
+	buf := bytes.NewReader(b)
+	err := binary.Read(buf, binary.BigEndian, &h.Marker)
+
+	err = binary.Read(buf, binary.BigEndian, &h.Len)
+	err = binary.Read(buf, binary.BigEndian, &h.Type)
+
+	switch h.Type {
+	case OPEN:
+		var m BgpOpenMsg
+		m.Hdr = h
+
+		err = binary.Read(buf, binary.BigEndian, &m.Ver)
+		err = binary.Read(buf, binary.BigEndian, &m.MyAs)
+		err = binary.Read(buf, binary.BigEndian, &m.Htime)
+		err = binary.Read(buf, binary.BigEndian, &m.BgpId)
+		err = binary.Read(buf, binary.BigEndian, &m.OptLen)
+
+		if m.OptLen > 0 {
+			m.Opt = make([]byte, m.OptLen)
+			err = binary.Read(buf, binary.BigEndian, &m.Opt)
+		}
+		return m, nil
+
+	case UPDATE:
+		var m BgpUpdateMsg
+		m.Hdr = h
+
+		if h.Len == MinMsgLen {
+			return m, nil
+		}
+
+		err = binary.Read(buf, binary.BigEndian, &m.UnfRoutesLen)
+		if m.UnfRoutesLen > 0 {
+			m.WithdRoutes = make([]byte, m.UnfRoutesLen)
+			err = binary.Read(buf, binary.BigEndian, &m.WithdRoutes)
+		}
+
+		err = binary.Read(buf, binary.BigEndian, &m.TotalPathAttrLen)
+		if m.TotalPathAttrLen > 0 {
+			m.NetLayerReachInfo = make([]byte, m.TotalPathAttrLen)
+			err = binary.Read(buf, binary.BigEndian, &m.NetLayerReachInfo)
+		}
+		return m, nil
+
+	case NOTIFICATION:
+		var m BgpNotifiMsg
+		m.Hdr = h
+
+		err = binary.Read(buf, binary.BigEndian, &m.ErrCode)
+		err = binary.Read(buf, binary.BigEndian, &m.ErrSubCode)
+
+		if h.Len > MinNotifiMsgLen {
+			m.Data = make([]byte, h.Len-MinNotifiMsgLen)
+			err = binary.Read(buf, binary.BigEndian, &m.ErrSubCode)
+		}
+
+		return m, nil
+
+	case KEEPALIVE:
+		return BgpKeepaliveMsg{h}, nil
+	}
+	return nil, err
+}
diff --git a/bgp/bgp_test.go b/bgp/bgp_test.go
@@ -0,0 +1,9 @@
+package bgp
+
+import (
+	"testing"
+)
+
+func TestParse(t *testing.T) {
+	t.Fatal("Test not implemented")
+}