ae8de95d89
Merge in DNS/adguard-home from 2234-move-to-internal to master
Squashed commit of the following:
commit d26a288cabeac86f9483fab307677b1027c78524
Author: Eugene Burkov <e.burkov@adguard.com>
Date: Fri Oct 30 12:44:18 2020 +0300
* all: move internal Go packages to internal/
Closes #2234.
130 lines
2.9 KiB
Go
130 lines
2.9 KiB
Go
package home
|
|
|
|
import (
|
|
"encoding/binary"
|
|
"strings"
|
|
"time"
|
|
|
|
"github.com/AdguardTeam/AdGuardHome/internal/dnsforward"
|
|
"github.com/AdguardTeam/golibs/cache"
|
|
"github.com/AdguardTeam/golibs/log"
|
|
"github.com/miekg/dns"
|
|
)
|
|
|
|
// RDNS - module context
|
|
type RDNS struct {
|
|
dnsServer *dnsforward.Server
|
|
clients *clientsContainer
|
|
ipChannel chan string // pass data from DNS request handling thread to rDNS thread
|
|
|
|
// Contains IP addresses of clients to be resolved by rDNS
|
|
// If IP address is resolved, it stays here while it's inside Clients.
|
|
// If it's removed from Clients, this IP address will be resolved once again.
|
|
// If IP address couldn't be resolved, it stays here for some time to prevent further attempts to resolve the same IP.
|
|
ipAddrs cache.Cache
|
|
}
|
|
|
|
// InitRDNS - create module context
|
|
func InitRDNS(dnsServer *dnsforward.Server, clients *clientsContainer) *RDNS {
|
|
r := RDNS{}
|
|
r.dnsServer = dnsServer
|
|
r.clients = clients
|
|
|
|
cconf := cache.Config{}
|
|
cconf.EnableLRU = true
|
|
cconf.MaxCount = 10000
|
|
r.ipAddrs = cache.New(cconf)
|
|
|
|
r.ipChannel = make(chan string, 256)
|
|
go r.workerLoop()
|
|
return &r
|
|
}
|
|
|
|
// Begin - add IP address to rDNS queue
|
|
func (r *RDNS) Begin(ip string) {
|
|
now := uint64(time.Now().Unix())
|
|
expire := r.ipAddrs.Get([]byte(ip))
|
|
if len(expire) != 0 {
|
|
exp := binary.BigEndian.Uint64(expire)
|
|
if exp > now {
|
|
return
|
|
}
|
|
// TTL expired
|
|
}
|
|
expire = make([]byte, 8)
|
|
const ttl = 1 * 60 * 60
|
|
binary.BigEndian.PutUint64(expire, now+ttl)
|
|
_ = r.ipAddrs.Set([]byte(ip), expire)
|
|
|
|
if r.clients.Exists(ip, ClientSourceRDNS) {
|
|
return
|
|
}
|
|
|
|
log.Tracef("rDNS: adding %s", ip)
|
|
select {
|
|
case r.ipChannel <- ip:
|
|
//
|
|
default:
|
|
log.Tracef("rDNS: queue is full")
|
|
}
|
|
}
|
|
|
|
// Use rDNS to get hostname by IP address
|
|
func (r *RDNS) resolve(ip string) string {
|
|
log.Tracef("Resolving host for %s", ip)
|
|
|
|
req := dns.Msg{}
|
|
req.Id = dns.Id()
|
|
req.RecursionDesired = true
|
|
req.Question = []dns.Question{
|
|
{
|
|
Qtype: dns.TypePTR,
|
|
Qclass: dns.ClassINET,
|
|
},
|
|
}
|
|
var err error
|
|
req.Question[0].Name, err = dns.ReverseAddr(ip)
|
|
if err != nil {
|
|
log.Debug("Error while calling dns.ReverseAddr(%s): %s", ip, err)
|
|
return ""
|
|
}
|
|
|
|
resp, err := r.dnsServer.Exchange(&req)
|
|
if err != nil {
|
|
log.Debug("Error while making an rDNS lookup for %s: %s", ip, err)
|
|
return ""
|
|
}
|
|
if len(resp.Answer) == 0 {
|
|
log.Debug("No answer for rDNS lookup of %s", ip)
|
|
return ""
|
|
}
|
|
ptr, ok := resp.Answer[0].(*dns.PTR)
|
|
if !ok {
|
|
log.Debug("not a PTR response for %s", ip)
|
|
return ""
|
|
}
|
|
|
|
log.Tracef("PTR response for %s: %s", ip, ptr.String())
|
|
if strings.HasSuffix(ptr.Ptr, ".") {
|
|
ptr.Ptr = ptr.Ptr[:len(ptr.Ptr)-1]
|
|
}
|
|
|
|
return ptr.Ptr
|
|
}
|
|
|
|
// Wait for a signal and then synchronously resolve hostname by IP address
|
|
// Add the hostname:IP pair to "Clients" array
|
|
func (r *RDNS) workerLoop() {
|
|
for {
|
|
var ip string
|
|
ip = <-r.ipChannel
|
|
|
|
host := r.resolve(ip)
|
|
if len(host) == 0 {
|
|
continue
|
|
}
|
|
|
|
_, _ = r.clients.AddHost(ip, host, ClientSourceRDNS)
|
|
}
|
|
}
|