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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,87 @@ | ||
| package dns | ||
|
|
||
| import ( | ||
| "context" | ||
| "net" | ||
| "time" | ||
| ) | ||
|
|
||
| var ( | ||
| dnsCache = make(map[string]bool) | ||
| dnsResolver = &net.Resolver{} | ||
| ) | ||
|
|
||
| func init() { | ||
| //dnsResolver.PreferGo = true | ||
| dnsResolver.StrictErrors = false | ||
| } | ||
|
|
||
| func noSuchHostDNSError(err error) bool { | ||
| dnsErr, ok := err.(*net.DNSError) | ||
| if !ok { | ||
| // not a DNSError | ||
| return false | ||
| } | ||
| return dnsErr.Err == "no such host" | ||
| } | ||
|
|
||
| // HasRecords does NS, CNAME, A, and AAAA lookups with a timeout | ||
| // returns error when no NS found, does not use TLDPlus1 | ||
| func HasRecords(domain string, timeout time.Duration) (bool, error) { | ||
| ctx, cancel := context.WithTimeout(context.Background(), timeout) | ||
| defer cancel() | ||
|
|
||
| // first check for NS | ||
| ns, err := dnsResolver.LookupNS(ctx, domain) | ||
| if err != nil && !noSuchHostDNSError(err) { | ||
| //fmt.Println("NS error ", err) | ||
| return false, err | ||
| } | ||
| if len(ns) > 0 { | ||
| //fmt.Printf("Found %d NS for %s\n", len(ns), domain) | ||
| return true, nil | ||
| } | ||
|
|
||
| // next check for CNAME | ||
| cname, err := dnsResolver.LookupCNAME(ctx, domain) | ||
| if err != nil && !noSuchHostDNSError(err) { | ||
| //fmt.Println("cname error ", err) | ||
| return false, err | ||
| } | ||
| if len(cname) > 2 { | ||
| //fmt.Printf("found CNAME %s for %s\n", cname, domain) | ||
| return true, nil | ||
| } | ||
|
|
||
| // next check for IP | ||
| addrs, err := dnsResolver.LookupHost(ctx, domain) | ||
| if err != nil && !noSuchHostDNSError(err) { | ||
| //fmt.Println("ip error ", err) | ||
| return false, err | ||
| } | ||
| if len(addrs) > 0 { | ||
| //fmt.Printf("Found %d IPs for %s\n", len(addrs), domain) | ||
| return true, nil | ||
| } | ||
|
|
||
| //fmt.Printf("Found no DNS records for %s\n", domain) | ||
| return false, nil | ||
| } | ||
|
|
||
| // HasRecordsCache returns true if the domain has no DNS records (at the tldplus1 level) | ||
| // uses a cache to store results to prevent lots of DNS lookups | ||
| func HasRecordsCache(domain string, timeout time.Duration) (bool, error) { | ||
| domain, err := TLDPlus1(domain) | ||
| if err != nil { | ||
| return false, err | ||
| } | ||
| hasDNS, found := dnsCache[domain] | ||
| if found { | ||
| return hasDNS, nil | ||
| } | ||
| hasRecords, err := HasRecords(domain, timeout) | ||
| if err != nil { | ||
| dnsCache[domain] = hasRecords | ||
| } | ||
| return hasRecords, err | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,42 @@ | ||
| package dns | ||
|
|
||
| import ( | ||
| "net/http" | ||
| "time" | ||
|
|
||
| "github.com/weppos/publicsuffix-go/publicsuffix" | ||
| ) | ||
|
|
||
| var ( | ||
| suffixListFindOptions = &publicsuffix.FindOptions{ | ||
| IgnorePrivate: true, | ||
| DefaultRule: publicsuffix.DefaultRule, | ||
| } | ||
| suffixListURL = "https://publicsuffix.org/list/public_suffix_list.dat" | ||
| suffixList = publicsuffix.DefaultList | ||
| nsCache = make(map[string]bool) | ||
| ) | ||
|
|
||
| // UpdatePublicSuffixList gets a new copy of the public suffix list from the internat and updates the built in copy with the new rules | ||
| func UpdatePublicSuffixList(timeout time.Duration) error { | ||
| suffixListParseOptions := &publicsuffix.ParserOption{ | ||
| PrivateDomains: !suffixListFindOptions.IgnorePrivate, | ||
| } | ||
| client := http.Client{ | ||
| Timeout: timeout, | ||
| } | ||
| resp, err := client.Get(suffixListURL) | ||
| if err != nil { | ||
| return err | ||
| } | ||
| defer resp.Body.Close() | ||
| newSuffixList := publicsuffix.NewList() | ||
| newSuffixList.Load(resp.Body, suffixListParseOptions) | ||
| suffixList = newSuffixList | ||
| return err | ||
| } | ||
|
|
||
| // TLDPlus1 returns TLD+1 of domain | ||
| func TLDPlus1(domain string) (string, error) { | ||
| return publicsuffix.DomainFromListWithOptions(suffixList, domain, suffixListFindOptions) | ||
| } |
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