AdguardTeam/AdGuardHome · error

parsing option code: %w

Error message

parsing option code: %w

What it means

Returned by parseDHCPOption when the first token of a 'code:type[:value]' option string fails to parse as an 8-bit unsigned decimal integer. DHCPv4 option codes must be 0–255; values like 256, 0x42, 'code', or an empty token trigger this.

Source

Thrown at internal/dhcpd/options_unix.go:184

func parseDHCPOption(s string) (code dhcpv4.OptionCode, val dhcpv4.OptionValue, err error) {
	defer func() { err = errors.Annotate(err, "invalid option string %q: %w", s) }()

	s = strings.TrimSpace(s)
	parts := strings.SplitN(s, " ", 3)

	var valStr string
	if pl := len(parts); pl < 3 {
		if pl < 2 || parts[1] != typDel {
			return nil, nil, errors.Error("bad option format")
		}
	} else {
		valStr = parts[2]
	}

	var code64 uint64
	code64, err = strconv.ParseUint(parts[0], 10, 8)
	if err != nil {
		return nil, nil, fmt.Errorf("parsing option code: %w", err)
	}

	val, err = parseDHCPOptionVal(parts[1], valStr)
	if err != nil {
		// Don't wrap an error since it's informative enough as is and there
		// also the deferred annotation.
		return nil, nil, err
	}

	return dhcpv4.GenericOptionCode(code64), val, nil
}

// prepareOptions builds the set of DHCP options according to host requirements
// document and values from conf.
func (s *v4Server) prepareOptions() {
	// Set default values of host configuration parameters listed in Appendix A
	// of RFC-2131.
	s.implicitOpts = dhcpv4.OptionsFromList(

View on GitHub (pinned to b41aefbe51)

Solutions

1. Use a decimal option code in 0–255 (convert hex from vendor docs, e.g. 0x2A → 42)
2. Ensure the string is 'code:type' or 'code:type:value' with no leading/trailing spaces
3. Look up the IANA DHCPv4 option registry to confirm the numeric code

Example fix

// before
"0x42:hex:68656c6c6f"
// -> parsing option code: strconv.ParseUint: parsing "0x42": invalid syntax

// after
"66:hex:68656c6c6f"

func optionCodeOK(s string) bool {
	v, err := strconv.ParseUint(strings.TrimSpace(s), 10, 8)
	return err == nil && v <= 255
}

When it happens

Trigger: Submitting an option string like '300:ip:1.2.3.4', '0x42:hex:ab', or a malformed split where the code token is empty or non-numeric.

Common situations: Vendor option tables listing codes above 255 or in hex; typos; extra spaces producing an empty first token when splitting on ':'.

Related errors

• decoding hex: %w
• parsing ip at index %d: %w
• decoding dur: %w
• decoding u%d: %w
• decoding bool: %w

AI-assisted analysis of AdguardTeam/AdGuardHome@b41aefbe51 (2026-08-27). Data as JSON: /api/errors/01b3fe8a469f6480. Report an issue: GitHub.