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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,74 @@ | ||
| package dns | ||
|
|
||
| import ( | ||
| "context" | ||
| "fmt" | ||
| "net" | ||
| "time" | ||
|
|
||
| "github.com/miekg/dns" | ||
| "github.com/rkonfj/toh/spec" | ||
| ) | ||
|
|
||
| var dnsClient *dns.Client = &dns.Client{} | ||
|
|
||
| var DefaultResolver Resolver = Resolver{ | ||
| Servers: []string{"8.8.8.8:53", "223.5.5.5:53"}, | ||
| Exchange: func(dnServer string, r *dns.Msg) (resp *dns.Msg, err error) { | ||
| dnsLookupCtx, cancel := context.WithTimeout(context.Background(), 25*time.Second) | ||
| defer cancel() | ||
| resp, _, err = dnsClient.ExchangeContext(dnsLookupCtx, r, dnServer) | ||
| return | ||
| }, | ||
| } | ||
|
|
||
| type Resolver struct { | ||
| Servers []string | ||
| Exchange func(dnServer string, r *dns.Msg) (*dns.Msg, error) | ||
| } | ||
|
|
||
| func LookupIP4(host string) (ips []net.IP, err error) { | ||
| return DefaultResolver.LookupIP(host, dns.TypeA) | ||
| } | ||
|
|
||
| func LookupIP6(host string) (ips []net.IP, err error) { | ||
| return DefaultResolver.LookupIP(host, dns.TypeAAAA) | ||
| } | ||
|
|
||
| func (r *Resolver) LookupIP(host string, t uint16) (ips []net.IP, err error) { | ||
| ip := net.ParseIP(host) | ||
| if ip != nil { | ||
| ips = append(ips, ip) | ||
| return | ||
| } | ||
| query := &dns.Msg{} | ||
| query.SetQuestion(dns.Fqdn(host), t) | ||
| var resp *dns.Msg | ||
| for _, dnServer := range r.Servers { | ||
| resp, err = r.Exchange(dnServer, query) | ||
| if err == nil { | ||
| break | ||
| } | ||
| } | ||
| if err != nil { | ||
| return | ||
| } | ||
| for _, a := range resp.Answer { | ||
| if a.Header().Rrtype == dns.TypeA { | ||
| ips = append(ips, a.(*dns.A).A) | ||
| } | ||
| if a.Header().Rrtype == dns.TypeAAAA { | ||
| ips = append(ips, a.(*dns.AAAA).AAAA) | ||
| } | ||
| } | ||
| if len(ips) == 0 { | ||
| if t == dns.TypeA { | ||
| err = spec.ErrDNSTypeANotFound | ||
| } else if t == dns.TypeAAAA { | ||
| err = spec.ErrDNSTypeAAAANotFound | ||
| } else { | ||
| err = fmt.Errorf("resolve %s : no type %s was found", host, dns.Type(t)) | ||
| } | ||
| } | ||
| return | ||
| } |