revert regex implementation

protocols/bgp/packet/large_community.go

@@ -2,13 +2,10 @@ package packet
 
 import (
 	"fmt"
-	"regexp"
 	"strconv"
 	"strings"
 )
 
-var largeCommunityRegEx = regexp.MustCompile("^\\(?\\d+,\\d+,\\d+\\)?$")
-
 type LargeCommunity struct {
 	GlobalAdministrator uint32
 	DataPart1           uint32
@@ -20,12 +17,13 @@ func (c LargeCommunity) String() string {
 }
 
 func ParseLargeCommunityString(s string) (com LargeCommunity, err error) {
-	if !largeCommunityRegEx.Match([]byte(s)) {
-		return com, fmt.Errorf("malformed large community string %s", s)
-	}
 	s = strings.Trim(s, "()")
 	t := strings.Split(s, ",")
 
+	if len(t) != 3 {
+		return com, fmt.Errorf("can not parse large community %s", s)
+	}
+
 	v, err := strconv.ParseUint(t[0], 10, 32)
 	if err != nil {
 		return com, err