mirror of
https://github.com/v2fly/v2ray-core.git
synced 2024-12-22 18:17:52 -05:00
232 lines
4.8 KiB
Go
232 lines
4.8 KiB
Go
package dns
|
|
|
|
import (
|
|
"context"
|
|
"sync"
|
|
"time"
|
|
|
|
"github.com/miekg/dns"
|
|
"v2ray.com/core"
|
|
"v2ray.com/core/common"
|
|
"v2ray.com/core/common/buf"
|
|
"v2ray.com/core/common/dice"
|
|
"v2ray.com/core/common/net"
|
|
"v2ray.com/core/common/signal"
|
|
"v2ray.com/core/transport/internet/udp"
|
|
)
|
|
|
|
var (
|
|
multiQuestionDNS = map[net.Address]bool{
|
|
net.IPAddress([]byte{8, 8, 8, 8}): true,
|
|
net.IPAddress([]byte{8, 8, 4, 4}): true,
|
|
net.IPAddress([]byte{9, 9, 9, 9}): true,
|
|
}
|
|
)
|
|
|
|
type ARecord struct {
|
|
IPs []net.IP
|
|
Expire time.Time
|
|
}
|
|
|
|
type NameServer interface {
|
|
QueryA(domain string) <-chan *ARecord
|
|
}
|
|
|
|
type PendingRequest struct {
|
|
expire time.Time
|
|
response chan<- *ARecord
|
|
}
|
|
|
|
type UDPNameServer struct {
|
|
sync.Mutex
|
|
address net.Destination
|
|
requests map[uint16]*PendingRequest
|
|
udpServer *udp.Dispatcher
|
|
cleanup *signal.PeriodicTask
|
|
}
|
|
|
|
func NewUDPNameServer(address net.Destination, dispatcher core.Dispatcher) *UDPNameServer {
|
|
s := &UDPNameServer{
|
|
address: address,
|
|
requests: make(map[uint16]*PendingRequest),
|
|
udpServer: udp.NewDispatcher(dispatcher),
|
|
}
|
|
s.cleanup = &signal.PeriodicTask{
|
|
Interval: time.Minute,
|
|
Execute: s.Cleanup,
|
|
}
|
|
common.Must(s.cleanup.Start())
|
|
return s
|
|
}
|
|
|
|
func (s *UDPNameServer) Cleanup() error {
|
|
now := time.Now()
|
|
s.Lock()
|
|
for id, r := range s.requests {
|
|
if r.expire.Before(now) {
|
|
close(r.response)
|
|
delete(s.requests, id)
|
|
}
|
|
}
|
|
s.Unlock()
|
|
return nil
|
|
}
|
|
|
|
func (s *UDPNameServer) AssignUnusedID(response chan<- *ARecord) uint16 {
|
|
var id uint16
|
|
s.Lock()
|
|
|
|
for {
|
|
id = dice.RollUint16()
|
|
if _, found := s.requests[id]; found {
|
|
time.Sleep(time.Millisecond * 500)
|
|
continue
|
|
}
|
|
newError("add pending request id ", id).AtDebug().WriteToLog()
|
|
s.requests[id] = &PendingRequest{
|
|
expire: time.Now().Add(time.Second * 8),
|
|
response: response,
|
|
}
|
|
break
|
|
}
|
|
s.Unlock()
|
|
return id
|
|
}
|
|
|
|
func (s *UDPNameServer) HandleResponse(payload *buf.Buffer) {
|
|
msg := new(dns.Msg)
|
|
err := msg.Unpack(payload.Bytes())
|
|
if err == dns.ErrTruncated {
|
|
newError("truncated message received. DNS server should still work. If you see anything abnormal, please submit an issue to v2ray-core.").AtWarning().WriteToLog()
|
|
} else if err != nil {
|
|
newError("failed to parse DNS response").Base(err).AtWarning().WriteToLog()
|
|
return
|
|
}
|
|
record := &ARecord{
|
|
IPs: make([]net.IP, 0, 16),
|
|
}
|
|
id := msg.Id
|
|
ttl := uint32(3600) // an hour
|
|
newError("handling response for id ", id, " content: ", msg).AtDebug().WriteToLog()
|
|
|
|
s.Lock()
|
|
request, found := s.requests[id]
|
|
if !found {
|
|
s.Unlock()
|
|
return
|
|
}
|
|
delete(s.requests, id)
|
|
s.Unlock()
|
|
|
|
for _, rr := range msg.Answer {
|
|
switch rr := rr.(type) {
|
|
case *dns.A:
|
|
record.IPs = append(record.IPs, rr.A)
|
|
if rr.Hdr.Ttl < ttl {
|
|
ttl = rr.Hdr.Ttl
|
|
}
|
|
case *dns.AAAA:
|
|
record.IPs = append(record.IPs, rr.AAAA)
|
|
if rr.Hdr.Ttl < ttl {
|
|
ttl = rr.Hdr.Ttl
|
|
}
|
|
}
|
|
}
|
|
record.Expire = time.Now().Add(time.Second * time.Duration(ttl))
|
|
|
|
request.response <- record
|
|
close(request.response)
|
|
}
|
|
|
|
func (s *UDPNameServer) buildAMsg(domain string, id uint16) *dns.Msg {
|
|
msg := new(dns.Msg)
|
|
msg.Id = id
|
|
msg.RecursionDesired = true
|
|
msg.Question = []dns.Question{
|
|
{
|
|
Name: dns.Fqdn(domain),
|
|
Qtype: dns.TypeA,
|
|
Qclass: dns.ClassINET,
|
|
}}
|
|
if multiQuestionDNS[s.address.Address] {
|
|
msg.Question = append(msg.Question, dns.Question{
|
|
Name: dns.Fqdn(domain),
|
|
Qtype: dns.TypeAAAA,
|
|
Qclass: dns.ClassINET,
|
|
})
|
|
}
|
|
|
|
return msg
|
|
}
|
|
|
|
func msgToBuffer(msg *dns.Msg) (*buf.Buffer, error) {
|
|
buffer := buf.New()
|
|
if err := buffer.Reset(func(b []byte) (int, error) {
|
|
writtenBuffer, err := msg.PackBuffer(b)
|
|
return len(writtenBuffer), err
|
|
}); err != nil {
|
|
return nil, err
|
|
}
|
|
return buffer, nil
|
|
}
|
|
|
|
func (s *UDPNameServer) QueryA(domain string) <-chan *ARecord {
|
|
response := make(chan *ARecord, 1)
|
|
id := s.AssignUnusedID(response)
|
|
|
|
msg := s.buildAMsg(domain, id)
|
|
b, err := msgToBuffer(msg)
|
|
if err != nil {
|
|
newError("failed to build A query for domain ", domain).Base(err).WriteToLog()
|
|
s.Lock()
|
|
delete(s.requests, id)
|
|
s.Unlock()
|
|
close(response)
|
|
return response
|
|
}
|
|
|
|
ctx, cancel := context.WithCancel(context.Background())
|
|
s.udpServer.Dispatch(ctx, s.address, b, s.HandleResponse)
|
|
|
|
go func() {
|
|
for i := 0; i < 2; i++ {
|
|
time.Sleep(time.Second)
|
|
s.Lock()
|
|
_, found := s.requests[id]
|
|
s.Unlock()
|
|
if !found {
|
|
break
|
|
}
|
|
b, _ := msgToBuffer(msg)
|
|
s.udpServer.Dispatch(ctx, s.address, b, s.HandleResponse)
|
|
}
|
|
cancel()
|
|
}()
|
|
|
|
return response
|
|
}
|
|
|
|
type LocalNameServer struct {
|
|
}
|
|
|
|
func (*LocalNameServer) QueryA(domain string) <-chan *ARecord {
|
|
response := make(chan *ARecord, 1)
|
|
|
|
go func() {
|
|
defer close(response)
|
|
|
|
ips, err := net.LookupIP(domain)
|
|
if err != nil {
|
|
newError("failed to lookup IPs for domain ", domain).Base(err).AtWarning().WriteToLog()
|
|
return
|
|
}
|
|
|
|
response <- &ARecord{
|
|
IPs: ips,
|
|
Expire: time.Now().Add(time.Hour),
|
|
}
|
|
}()
|
|
|
|
return response
|
|
}
|