owasp-amass/amass · error

integer parsing failed

Error message

integer parsing failed

What it means

ParseInts is a flag.Value implementation for comma-separated integer list flags. Set first rejects an empty string with this error, then parses each comma-separated token with strconv.Atoi; any token that is not a plain integer aborts the whole flag, guaranteeing the resulting []int contains only valid values.

Source

Thrown at internal/afmt/parse.go:69

func (p *ParseInts) String() string {
	if p == nil {
		return ""
	}
	var builder strings.Builder
	for i, n := range *p {
		if i > 0 {
			builder.WriteRune(',')
		}
		builder.WriteString(strconv.Itoa(n))
	}
	return builder.String()
}

// Set implements the flag.Value interface.
func (p *ParseInts) Set(s string) error {
	if s == "" {
		return fmt.Errorf("integer parsing failed")
	}

	nums := strings.Split(s, ",")
	for _, n := range nums {
		i, err := strconv.Atoi(strings.TrimSpace(n))
		if err != nil {
			return err
		}
		*p = append(*p, i)
	}
	return nil
}

func (p *ParseIPs) String() string {
	if p == nil {
		return ""
	}
	var builder strings.Builder

View on GitHub (pinned to 79299dce87)

Solutions

1. Ensure the value is non-empty and every comma-separated token is a plain integer, e.g. "80,443,8080".
2. Remove range tokens ("1-100"); enumerate each integer explicitly.
3. Verify the shell variable feeding the flag is set before invocation.

Example fix

// before
-ports "80,8443-8444"    // integer parsing failed (range token)
// after
-ports "80,8443"         // enumerate each port explicitly

func validateIntsFlag(value string) error {
	if strings.TrimSpace(value) == "" {
		return errors.New("flag requires a non-empty integer list")
	}
	for _, n := range strings.Split(value, ",") {
		if _, err := strconv.Atoi(strings.TrimSpace(n)); err != nil {
			return fmt.Errorf("token %q is not an integer", n)
		}
	}
	return nil
}

func isIntList(s string) bool {
	for _, n := range strings.Split(s, ",") {
		if _, err := strconv.Atoi(strings.TrimSpace(n)); err != nil { return false }
	}
	return strings.TrimSpace(s) != ""
}

When it happens

Trigger: Calling Set("") on a *ParseInts (empty flag value), or any non-empty input where a token fails strconv.Atoi after trimming: "80,abc,443", range tokens like "1-100", tokens with stray characters, or integers out of int range.

Common situations: Port lists written with ranges ("8443-8444") which this parser does not expand, empty environment variables in scripts, copy-paste with extra whitespace or punctuation.

Understand the failure class

Background: "unknown output mode", "invalid value for flag", "expects true/false": fixing invalid flag value errors in CLI tools — this error's family across 24 libraries.

Related errors

• String parsing failed
• %s is not a valid IP address or range
• ASN parsing failed
• IP address parsing failed
• IP address parsing failed

AI-assisted analysis of owasp-amass/amass@79299dce87 (2026-09-06). Data as JSON: /api/errors/f2cb90c597574beb. Report an issue: GitHub.