1db3056594
Classify DNS names as apex domains or hostnames using the Public Suffix List (golang.org/x/net/publicsuffix). Correctly handles multi-level TLDs like .co.uk and .com.au.
62 lines
1.4 KiB
Go
62 lines
1.4 KiB
Go
// Package config provides application configuration via Viper.
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package config
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import (
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"fmt"
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"strings"
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"golang.org/x/net/publicsuffix"
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)
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// ClassifyTarget determines whether a DNS name is an apex domain
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// (eTLD+1) or a hostname (subdomain of an eTLD+1). Returns
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// "domain" or "hostname". Returns an error if the name is itself
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// a public suffix (e.g. "co.uk") or otherwise invalid.
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func ClassifyTarget(name string) (string, error) {
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// Normalize: lowercase, strip trailing dot.
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name = strings.ToLower(strings.TrimSuffix(name, "."))
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if name == "" {
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return "", fmt.Errorf("empty target name")
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}
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apex, err := publicsuffix.EffectiveTLDPlusOne(name)
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if err != nil {
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return "", fmt.Errorf(
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"invalid target %q: %w", name, err,
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)
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}
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if name == apex {
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return "domain", nil
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}
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return "hostname", nil
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}
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// classifyTargets splits a list of DNS names into apex domains
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// and hostnames using the Public Suffix List.
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func classifyTargets(
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targets []string,
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) (domains, hostnames []string, err error) {
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for _, target := range targets {
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kind, classifyErr := ClassifyTarget(target)
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if classifyErr != nil {
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return nil, nil, classifyErr
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}
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switch kind {
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case "domain":
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domains = append(domains, strings.ToLower(
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strings.TrimSuffix(target, "."),
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))
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case "hostname":
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hostnames = append(hostnames, strings.ToLower(
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strings.TrimSuffix(target, "."),
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))
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}
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}
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return domains, hostnames, nil
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}
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