server: handle over 4096 byte size message

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Signed-off-by: FUJITA Tomonori <[email protected]>

packet/bgp.go

@@ -2584,7 +2584,8 @@ type BGPBody interface {
 }
 
 const (
-	BGP_HEADER_LENGTH = 19
+	BGP_HEADER_LENGTH      = 19
+	BGP_MAX_MESSAGE_LENGTH = 4096
 )
 
 type BGPHeader struct {

packet/validate.go

@@ -1,6 +1,7 @@
 package bgp
 
 import (
+	"encoding/binary"
 	"github.com/osrg/gobgp/config"
 	"net"
 	"strconv"
@@ -139,3 +140,12 @@ func ValidateFlags(t BGPAttrType, flags uint8) (bool, string) {
 	}
 	return true, ""
 }
+
+func ValidateBGPMessage(m *BGPMessage) error {
+	if m.Header.Len > BGP_MAX_MESSAGE_LENGTH {
+		buf := make([]byte, 2)
+		binary.BigEndian.PutUint16(buf, m.Header.Len)
+		return NewMessageError(BGP_ERROR_MESSAGE_HEADER_ERROR, BGP_ERROR_SUB_BAD_MESSAGE_LENGTH, buf, "too long length")
+	}
+	return nil
+}

server/fsm.go

@@ -225,6 +225,9 @@ func (h *FSMHandler) recvMessageWithError() error {
 
 	var fmsg *fsmMsg
 	m, err := bgp.ParseBGPBody(hd, bodyBuf)
+	if err == nil {
+		err = bgp.ValidateBGPMessage(m)
+	}
 	if err != nil {
 		log.WithFields(log.Fields{
 			"Topic": "Peer",