fixes osrg#2645 Panic when adding FlowspecComponentItem with to large value

Author: aelg

pkg/packet/bgp/bgp.go

@@ -4374,13 +4374,10 @@ func NewFlowSpecComponentItem(op uint8, value uint64) *FlowSpecComponentItem {
 					return uint32(i)
 				}
 			}
-			// return invalid order
-			return 4
+			// Return 8 octet order
+			return 3
 		}()
 	}
-	if order > 3 {
-		return nil
-	}
 	v.Op = uint8(uint32(v.Op) | order<<4)
 	return v
 }

pkg/packet/bgp/bgp_test.go

@@ -18,6 +18,7 @@ package bgp
 import (
 	"bytes"
 	"encoding/binary"
+	"math"
 	"net"
 	"os"
 	"path/filepath"
@@ -443,6 +444,28 @@ func Test_FlowSpecNlri(t *testing.T) {
 	assert.Equal(n1, n2)
 }
 
+func Test_NewFlowSpecComponentItemLength(t *testing.T) {
+	item := NewFlowSpecComponentItem(0, 0)
+	assert.Equal(t, 1, item.Len())
+	item = NewFlowSpecComponentItem(0, math.MaxUint8)
+	assert.Equal(t, 1, item.Len())
+
+	item = NewFlowSpecComponentItem(0, math.MaxUint8+1)
+	assert.Equal(t, 2, item.Len())
+	item = NewFlowSpecComponentItem(0, math.MaxUint16)
+	assert.Equal(t, 2, item.Len())
+
+	item = NewFlowSpecComponentItem(0, math.MaxUint16+1)
+	assert.Equal(t, 4, item.Len())
+	item = NewFlowSpecComponentItem(0, math.MaxUint32)
+	assert.Equal(t, 4, item.Len())
+
+	item = NewFlowSpecComponentItem(0, math.MaxUint32+1)
+	assert.Equal(t, 8, item.Len())
+	item = NewFlowSpecComponentItem(0, math.MaxUint64)
+	assert.Equal(t, 8, item.Len())
+}
+
 func Test_LinkBandwidthExtended(t *testing.T) {
 	assert := assert.New(t)
 	exts := make([]ExtendedCommunityInterface, 0)