XTLS/Xray-core · error

invalid padding lenth/gap parameter: %s

Error message

invalid padding lenth/gap parameter: %s

What it means

Error "invalid padding lenth/gap parameter: %s" thrown in XTLS/Xray-core.

Source

Thrown at proxy/vless/encryption/common.go:231

	l = int(h[3])<<8 | int(h[4])
	if h[0] != 23 || h[1] != 3 || h[2] != 3 {
		l = 0
	}
	if l < 17 || l > 16640 { // TLS 1.3 max record: 16384 + 256 (RFC 8446 §5.2)
		err = errors.New("invalid header: " + fmt.Sprintf("%v", h[:5])) // DO NOT CHANGE: relied by client's Read()
	}
	return
}

func ParsePadding(padding string, paddingLens, paddingGaps *[][3]int) (err error) {
	if padding == "" {
		return
	}
	maxLen := 0
	for i, s := range strings.Split(padding, ".") {
		x := strings.Split(s, "-")
		if len(x) < 3 || x[0] == "" || x[1] == "" || x[2] == "" {
			return errors.New("invalid padding lenth/gap parameter: " + s)
		}
		y := [3]int{}
		if y[0], err = strconv.Atoi(x[0]); err != nil {
			return
		}
		if y[1], err = strconv.Atoi(x[1]); err != nil {
			return
		}
		if y[2], err = strconv.Atoi(x[2]); err != nil {
			return
		}
		if i == 0 && (y[0] < 100 || y[1] < 18+17 || y[2] < 18+17) {
			return errors.New("first padding length must not be smaller than 35")
		}
		if i%2 == 0 {
			*paddingLens = append(*paddingLens, y)
			maxLen += max(y[1], y[2])
		} else {

View on GitHub (pinned to 7d214f8b09)

When it happens

Trigger: Thrown at proxy/vless/encryption/common.go:231 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of XTLS/Xray-core@7d214f8b09 (2026-08-15). Data as JSON: /api/errors/0d3e12271cbd8649. Report an issue: GitHub.