api/grpc_server: Avoid index error when invalid set-med value

Currently, with a invalid "set-med" value in a policy action, GoBGP will
raise panic of "index out of range" because the unmatched regular
expression is not handled.

This patch fixes to handle errors during parsing the given med value.

Signed-off-by: IWASE Yusuke <iwase.yusuke0@gmail.com>

1 files changed, 12 insertions, 5 deletions

diff --git a/api/grpc_server.go b/api/grpc_server.go
index 161bc826..5b10b055 100644
--- a/api/grpc_server.go
+++ b/api/grpc_server.go
@@ -1606,17 +1606,24 @@ func toStatementApi(s *config.Statement) *Statement {
 				Communities: s.Actions.BgpActions.SetCommunity.SetCommunityMethod.CommunitiesList}
 		}(),
 		Med: func() *MedAction {
-			if len(string(s.Actions.BgpActions.SetMed)) == 0 {
+			medStr := strings.TrimSpace(string(s.Actions.BgpActions.SetMed))
+			if len(medStr) == 0 {
+				return nil
+			}
+			re := regexp.MustCompile("([+-]?)(\\d+)")
+			matches := re.FindStringSubmatch(medStr)
+			if len(matches) == 0 {
 				return nil
 			}
-			exp := regexp.MustCompile("^(\\+|\\-)?(\\d+)$")
-			elems := exp.FindStringSubmatch(string(s.Actions.BgpActions.SetMed))
 			action := MedActionType_MED_REPLACE
-			switch elems[1] {
+			switch matches[1] {
 			case "+", "-":
 				action = MedActionType_MED_MOD
 			}
-			value, _ := strconv.Atoi(string(s.Actions.BgpActions.SetMed))
+			value, err := strconv.Atoi(matches[1] + matches[2])
+			if err != nil {
+				return nil
+			}
 			return &MedAction{
 				Value: int64(value),
 				Type:  action,