table: fix potential panics in tableKey

It is possible for a call from other Table methods for an interface that does
not match the tables route family to reach the type assertion and panic. This
change better reflects the intention of the code by checking the concrete type
using a type switch instead.

1 files changed, 7 insertions, 9 deletions

diff --git a/table/table.go b/table/table.go
index b26095f8..9d8edf40 100644
--- a/table/table.go
+++ b/table/table.go
@@ -291,18 +291,16 @@ func (t *Table) setDestination(dst *Destination) {
 }
 
 func (t *Table) tableKey(nlri bgp.AddrPrefixInterface) string {
-	switch t.routeFamily {
-	case bgp.RF_IPv4_UC:
+	switch T := nlri.(type) {
+	case *bgp.IPAddrPrefix:
 		b := make([]byte, 5)
-		ip := nlri.(*bgp.IPAddrPrefix)
-		copy(b, ip.Prefix.To4())
-		b[4] = ip.Length
+		copy(b, T.Prefix.To4())
+		b[4] = T.Length
 		return *(*string)(unsafe.Pointer(&b))
-	case bgp.RF_IPv6_UC:
+	case *bgp.IPv6AddrPrefix:
 		b := make([]byte, 17)
-		ip := nlri.(*bgp.IPv6AddrPrefix)
-		copy(b, ip.Prefix.To16())
-		b[16] = ip.Length
+		copy(b, T.Prefix.To16())
+		b[16] = T.Length
 		return *(*string)(unsafe.Pointer(&b))
 	}
 	return nlri.String()