go_tab-magic/pkg/resolver/resolver.go
Matt Burchett 0418dcefc0 Fixing
2018-11-30 14:21:31 -06:00

98 lines
2.1 KiB
Go

package resolver
import (
"encoding/json"
"errors"
"fmt"
"log"
"strings"
"git.linuxrocker.com/mattburchett/go_tab-magic/pkg/config"
"git.linuxrocker.com/mattburchett/go_tab-magic/pkg/model"
"github.com/miekg/dns"
)
// LookupName returns IPv4 address from A record or error.
func lookupName(fqdn, serverAddr string) (string, error) {
m := &dns.Msg{}
m.SetQuestion(dns.Fqdn(fqdn), dns.TypeA)
in, err := dns.Exchange(m, serverAddr)
if err != nil {
return "", err
}
if len(in.Answer) < 1 {
return "", errors.New("no Answer")
}
if a, ok := in.Answer[0].(*dns.A); ok {
ip := a.A.String()
return ip, nil
}
return "", errors.New("no A record returned")
}
func PerformZoneTransfer(config config.Config) []string {
data := make([]string, 0)
// Do the transfer
for _, i := range config.Domains {
server := fmt.Sprintf("%s:%d", config.Resolver, config.ResolverPort)
tr := dns.Transfer{}
m := &dns.Msg{}
m.SetAxfr(dns.Fqdn(i))
in, err := tr.In(m, server)
if err != nil {
log.Fatal(err)
}
for ex := range in {
for _, a := range ex.RR {
var ip, hostname, txt string
switch v := a.(type) {
case *dns.TXT:
txt = string(v.Txt[0])
hostname = v.Hdr.Name
cip, err := lookupName(strings.TrimRight(v.Hdr.Name, "."), server)
if err != nil || cip == "" {
continue
}
ip = cip
case *dns.A:
ip = v.A.String()
hostname = v.Hdr.Name
case *dns.CNAME:
cip, err := lookupName(v.Target, server)
if err != nil || cip == "" {
continue
}
ip = cip
hostname = v.Hdr.Name
default:
continue
}
data = append(data, fmt.Sprintf("%v %v %v", strings.TrimRight(hostname, "."), ip, txt))
}
}
}
// fmt.Println(data)
// resultsToJSON(data)
return data
}
func resultsToJSON(data []string) {
jsonData := make([][]byte, 0)
for _, i := range data {
splitStrings := strings.Split(i, " ")
hostname := splitStrings[0]
ip := splitStrings[1]
txt := splitStrings[2]
dns := &model.Results{IP: ip, Hostname: hostname, TXT: txt}
b, err := json.Marshal(dns)
if err != nil {
fmt.Println(err)
}
jsonData = append(jsonData, b)
}
}