mirror of https://github.com/slackhq/nebula.git
126 lines
2.6 KiB
Go
126 lines
2.6 KiB
Go
package nebula
|
|
|
|
import (
|
|
"fmt"
|
|
"net"
|
|
"strconv"
|
|
"sync"
|
|
|
|
"github.com/miekg/dns"
|
|
)
|
|
|
|
// This whole thing should be rewritten to use context
|
|
|
|
var dnsR *dnsRecords
|
|
|
|
type dnsRecords struct {
|
|
sync.RWMutex
|
|
dnsMap map[string]string
|
|
hostMap *HostMap
|
|
}
|
|
|
|
func newDnsRecords(hostMap *HostMap) *dnsRecords {
|
|
return &dnsRecords{
|
|
dnsMap: make(map[string]string),
|
|
hostMap: hostMap,
|
|
}
|
|
}
|
|
|
|
func (d *dnsRecords) Query(data string) string {
|
|
d.RLock()
|
|
if r, ok := d.dnsMap[data]; ok {
|
|
d.RUnlock()
|
|
return r
|
|
}
|
|
d.RUnlock()
|
|
return ""
|
|
}
|
|
|
|
func (d *dnsRecords) QueryCert(data string) string {
|
|
ip := net.ParseIP(data[:len(data)-1])
|
|
if ip == nil {
|
|
return ""
|
|
}
|
|
iip := ip2int(ip)
|
|
hostinfo, err := d.hostMap.QueryVpnIP(iip)
|
|
if err != nil {
|
|
return ""
|
|
}
|
|
q := hostinfo.GetCert()
|
|
if q == nil {
|
|
return ""
|
|
}
|
|
cert := q.Details
|
|
c := fmt.Sprintf("\"Name: %s\" \"Ips: %s\" \"Subnets %s\" \"Groups %s\" \"NotBefore %s\" \"NotAFter %s\" \"PublicKey %x\" \"IsCA %t\" \"Issuer %s\"", cert.Name, cert.Ips, cert.Subnets, cert.Groups, cert.NotBefore, cert.NotAfter, cert.PublicKey, cert.IsCA, cert.Issuer)
|
|
return c
|
|
}
|
|
|
|
func (d *dnsRecords) Add(host, data string) {
|
|
d.Lock()
|
|
d.dnsMap[host] = data
|
|
d.Unlock()
|
|
}
|
|
|
|
func parseQuery(m *dns.Msg, w dns.ResponseWriter) {
|
|
for _, q := range m.Question {
|
|
switch q.Qtype {
|
|
case dns.TypeA:
|
|
l.Debugf("Query for A %s", q.Name)
|
|
ip := dnsR.Query(q.Name)
|
|
if ip != "" {
|
|
rr, err := dns.NewRR(fmt.Sprintf("%s A %s", q.Name, ip))
|
|
if err == nil {
|
|
m.Answer = append(m.Answer, rr)
|
|
}
|
|
}
|
|
case dns.TypeTXT:
|
|
a, _, _ := net.SplitHostPort(w.RemoteAddr().String())
|
|
b := net.ParseIP(a)
|
|
// We don't answer these queries from non nebula nodes or localhost
|
|
//l.Debugf("Does %s contain %s", b, dnsR.hostMap.vpnCIDR)
|
|
if !dnsR.hostMap.vpnCIDR.Contains(b) && a != "127.0.0.1" {
|
|
return
|
|
}
|
|
l.Debugf("Query for TXT %s", q.Name)
|
|
ip := dnsR.QueryCert(q.Name)
|
|
if ip != "" {
|
|
rr, err := dns.NewRR(fmt.Sprintf("%s TXT %s", q.Name, ip))
|
|
if err == nil {
|
|
m.Answer = append(m.Answer, rr)
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
func handleDnsRequest(w dns.ResponseWriter, r *dns.Msg) {
|
|
m := new(dns.Msg)
|
|
m.SetReply(r)
|
|
m.Compress = false
|
|
|
|
switch r.Opcode {
|
|
case dns.OpcodeQuery:
|
|
parseQuery(m, w)
|
|
}
|
|
|
|
w.WriteMsg(m)
|
|
}
|
|
|
|
func dnsMain(hostMap *HostMap) {
|
|
|
|
dnsR = newDnsRecords(hostMap)
|
|
|
|
// attach request handler func
|
|
dns.HandleFunc(".", handleDnsRequest)
|
|
|
|
// start server
|
|
port := 53
|
|
server := &dns.Server{Addr: ":" + strconv.Itoa(port), Net: "udp"}
|
|
l.Debugf("Starting DNS responder at %d\n", port)
|
|
err := server.ListenAndServe()
|
|
defer server.Shutdown()
|
|
if err != nil {
|
|
l.Errorf("Failed to start server: %s\n ", err.Error())
|
|
}
|
|
}
|