package tcping import ( "context" "fmt" "net" "strings" "time" ) func timeIt(f func() interface{}) (int64, interface{}) { startAt := time.Now() res := f() endAt := time.Now() return endAt.UnixNano() - startAt.UnixNano(), res } // UseCustomeDNS will set the dns to default DNS resolver for global func UseCustomeDNS(dns []string) { resolver := net.Resolver{ PreferGo: true, Dial: func(ctx context.Context, network, address string) (conn net.Conn, err error) { for _, addr := range dns { if conn, err = net.Dial("udp", addr+":53"); err != nil { continue } else { return conn, nil } } return }, } net.DefaultResolver = &resolver } // FormatIP - trim spaces and format IP // // IP - the provided IP // // string - return "" if the input is neither valid IPv4 nor valid IPv6 // return IPv4 in format like "192.168.9.1" // return IPv6 in format like "[2002:ac1f:91c5:1::bd59]" func FormatIP(IP string) string { host := strings.Trim(IP, "[ ]") if parseIP := net.ParseIP(host); parseIP != nil && parseIP.To4() == nil { host = fmt.Sprintf("[%s]", host) } return host }