85 lines
1.9 KiB
Go
85 lines
1.9 KiB
Go
package resolver
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import (
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"errors"
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"fmt"
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"log"
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"strings"
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"git.linuxrocker.com/mattburchett/go_tab-magic/pkg/utils"
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"git.linuxrocker.com/mattburchett/go_tab-magic/pkg/config"
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"github.com/miekg/dns"
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)
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// LookupName returns IPv4 address from A record or error.
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func lookupName(fqdn, serverAddr string, debug bool) (string, error) {
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if debug {
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defer utils.LogElapsedTime("Lookup Name")
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}
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m := &dns.Msg{}
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m.SetQuestion(dns.Fqdn(fqdn), dns.TypeA)
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in, err := dns.Exchange(m, serverAddr)
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if err != nil {
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return "", err
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}
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if len(in.Answer) < 1 {
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return "", errors.New("no Answer")
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}
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if a, ok := in.Answer[0].(*dns.A); ok {
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ip := a.A.String()
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return ip, nil
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}
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return "", errors.New("no A record returned")
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}
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// PerformZoneTransfer performs zone transfers and gathers a list from config.Domains
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func PerformZoneTransfer(config config.Config, debug bool) []string {
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if debug {
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defer utils.LogElapsedTime("Perform Zone Transfer")
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}
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data := make([]string, 0)
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// Do the transfer
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for _, i := range config.Domains {
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server := fmt.Sprintf("%s:%d", config.Resolver, config.ResolverPort)
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tr := dns.Transfer{}
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m := &dns.Msg{}
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m.SetAxfr(dns.Fqdn(i))
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in, err := tr.In(m, server)
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if err != nil {
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log.Fatal(err)
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}
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for ex := range in {
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for _, a := range ex.RR {
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var ip, hostname, txt string
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switch v := a.(type) {
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case *dns.TXT:
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txt = string(v.Txt[0])
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hostname = v.Hdr.Name
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cip, err := lookupName(strings.TrimRight(v.Hdr.Name, "."), server, debug)
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if err != nil || cip == "" {
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continue
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}
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ip = cip
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case *dns.A:
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ip = v.A.String()
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hostname = v.Hdr.Name
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case *dns.CNAME:
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cip, err := lookupName(v.Target, server, debug)
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if err != nil || cip == "" {
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continue
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}
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ip = cip
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hostname = v.Hdr.Name
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default:
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continue
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}
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data = append(data, fmt.Sprintf("%v %v %v", strings.TrimRight(hostname, "."), ip, txt))
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}
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}
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}
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return data
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}
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