Function normalize_allowed_domains 

pub fn normalize_allowed_domains(
    domains: Vec<String>,
    label: &str,
) -> Result<Vec<String>, Error>

Normalize a whole allowlist, sorted and deduplicated.

label names the configuration surface in the error message so the operator can find the offending entry (for example "http_request.allowed_domains"). Fails if any entry is not a valid domain, hostname, IPv4, or IPv6 address.

Errors

Returns an error naming every rejected entry when one or more entries fail normalize_domain.