shadow1ng/fscan · error

parser_invalid_end_ip

Error message

parser_invalid_end_ip

What it means

In parseIPRangeString, for full-format ranges (end contains '.'), the end part is parsed with net.ParseIP. If invalid, 'parser_invalid_end_ip' is returned with the offending string. It means the right side of the '-' range is not a parseable IP address.

Source

Thrown at common/parsers/parsers.go:363

	}

	startIPStr := strings.TrimSpace(parts[0])
	endIPStr := strings.TrimSpace(parts[1])

	startIP := net.ParseIP(startIPStr)
	if startIP == nil {
		return nil, fmt.Errorf("%s", i18n.Tr("parser_invalid_start_ip", startIPStr))
	}

	// 处理简写格式 (如: 192.168.1.1-100)
	if len(endIPStr) < 4 || !strings.Contains(endIPStr, ".") {
		return parseIPShortRange(startIPStr, endIPStr)
	}

	// 处理完整格式 (如: 192.168.1.1-192.168.1.100)
	endIP := net.ParseIP(endIPStr)
	if endIP == nil {
		return nil, fmt.Errorf("%s", i18n.Tr("parser_invalid_end_ip", endIPStr))
	}

	return parseIPFullRange(startIP, endIP)
}

// parseIPShortRange 解析短格式IP范围
func parseIPShortRange(startIPStr, endSuffix string) ([]string, error) {
	endNum, err := strconv.Atoi(endSuffix)
	if err != nil || endNum > 255 {
		return nil, fmt.Errorf("%s", i18n.Tr("parser_invalid_ip_end_val", endSuffix))
	}

	ipParts := strings.Split(startIPStr, ".")
	if len(ipParts) != 4 {
		return nil, fmt.Errorf("%s", i18n.Tr("parser_invalid_ip_fmt", startIPStr))
	}

	prefixIP := strings.Join(ipParts[0:3], ".")

View on GitHub (pinned to 95cc12e753)

Solutions

1. Write the end address as a full dotted-quad IPv4, e.g. 192.168.1.1-192.168.1.254
2. Use shorthand form 192.168.1.1-100 if only the last octet varies (and end is short/undotted)
3. Pre-validate with net.ParseIP(parts[1]) != nil before calling ParseIP

Example fix

// before
ParseIP("192.168.1.1-192.168.1", "")
// after
ParseIP("192.168.1.1-192.168.1.254", "")

func validEndIP(rangeStr string) bool {
	parts := strings.Split(rangeStr, "-")
	return len(parts) == 2 && net.ParseIP(strings.TrimSpace(parts[1])) != nil
}

if !validEndIP(rangeStr) {
	return fmt.Errorf("end of %q is not an IP", rangeStr)
}
_, err := parsers.ParseIP(rangeStr, "")

When it happens

Trigger: parseIPRangeString receiving ranges like '192.168.1.1-192.168.1' or '192.168.1.1-.100' where the end token fails net.ParseIP (and is long enough / dotted enough to skip the shorthand path).

Common situations: Truncated end addresses in hand-written target lists, copy-paste errors dropping an octet, or scripts substituting variables that resolve to empty/malformed ends.

Understand the failure class

Background: "Must be a positive integer", "Invalid value", "Unsupported": the invalid-argument-value error family, when a library rejects the value you pass — this error's family across 35 libraries.

Related errors

• parser_ip_range_failed: %w
• parser_invalid_start_ip
• parser_cidr_failed: %w
• parser_invalid_ip_range_fmt
• parser_ip_range_failed: %w

AI-assisted analysis of shadow1ng/fscan@95cc12e753 (2026-09-06). Data as JSON: /api/errors/7611e01432230c1a. Report an issue: GitHub.