packet: support cisco-ish flowspec tcp-flag serializing

// same as juniper matching ack+syn
$ gobgp global rib -a ipv4-flowspec match tcp-flags ack syn then discard
// [NEW] same as cisco matching ack+syn
$ gobgp global rib -a ipv4-flowspec match tcp-flags 'ack&syn' then discard

Signed-off-by: ISHIDA Wataru <ishida.wataru@lab.ntt.co.jp>

1 files changed, 9 insertions, 9 deletions

diff --git a/packet/bgp.go b/packet/bgp.go
index 3dd18be3..aeab46f8 100644
--- a/packet/bgp.go
+++ b/packet/bgp.go
@@ -2107,19 +2107,19 @@ func flowSpecTcpFlagParser(rf RouteFamily, args []string) (FlowSpecComponentInte
 		ss = append(ss, v)
 	}
 	protos := strings.Join(ss, "|")
-	exp := regexp.MustCompile(fmt.Sprintf("^%s (((%s) )*)(%s)$", FlowSpecNameMap[FLOW_SPEC_TYPE_TCP_FLAG], protos, protos))
+	exp := regexp.MustCompile(fmt.Sprintf("^%s ((((%s)\\&)*(%s) )*(((%s)\\&)*(%s)))$", FlowSpecNameMap[FLOW_SPEC_TYPE_TCP_FLAG], protos, protos, protos, protos))
 	elems := exp.FindStringSubmatch(strings.Join(args, " "))
+	if len(elems) < 1 {
+		return nil, fmt.Errorf("invalid flag format")
+	}
 	items := make([]*FlowSpecComponentItem, 0)
-	if elems[1] != "" {
-		for _, v := range strings.Split(elems[1], " ") {
-			p, ok := TCPFlagValueMap[v]
-			if !ok {
-				continue
-			}
-			items = append(items, NewFlowSpecComponentItem(0, int(p)))
+	for _, v := range strings.Split(elems[1], " ") {
+		flag := 0
+		for _, e := range strings.Split(v, "&") {
+			flag |= int(TCPFlagValueMap[e])
 		}
+		items = append(items, NewFlowSpecComponentItem(0, flag))
 	}
-	items = append(items, NewFlowSpecComponentItem(0, int(TCPFlagValueMap[elems[4]])))
 	return NewFlowSpecComponent(FLOW_SPEC_TYPE_TCP_FLAG, items), nil
 }