sing-box/outbound/dns.go
2024-05-21 15:12:03 +08:00

256 lines
6.4 KiB
Go

package outbound
import (
"context"
"encoding/binary"
"net"
"os"
"github.com/sagernet/sing-box/adapter"
C "github.com/sagernet/sing-box/constant"
"github.com/sagernet/sing-dns"
"github.com/sagernet/sing/common"
"github.com/sagernet/sing/common/buf"
"github.com/sagernet/sing/common/bufio"
"github.com/sagernet/sing/common/canceler"
M "github.com/sagernet/sing/common/metadata"
N "github.com/sagernet/sing/common/network"
"github.com/sagernet/sing/common/task"
mDNS "github.com/miekg/dns"
)
var _ adapter.Outbound = (*DNS)(nil)
type DNS struct {
myOutboundAdapter
}
func NewDNS(router adapter.Router, tag string) *DNS {
return &DNS{
myOutboundAdapter{
protocol: C.TypeDNS,
network: []string{N.NetworkTCP, N.NetworkUDP},
router: router,
tag: tag,
},
}
}
func (d *DNS) DialContext(ctx context.Context, network string, destination M.Socksaddr) (net.Conn, error) {
return nil, os.ErrInvalid
}
func (d *DNS) ListenPacket(ctx context.Context, destination M.Socksaddr) (net.PacketConn, error) {
return nil, os.ErrInvalid
}
func (d *DNS) NewConnection(ctx context.Context, conn net.Conn, metadata adapter.InboundContext) error {
metadata.Destination = M.Socksaddr{}
defer conn.Close()
for {
err := d.handleConnection(ctx, conn, metadata)
if err != nil {
return err
}
}
}
func (d *DNS) handleConnection(ctx context.Context, conn net.Conn, metadata adapter.InboundContext) error {
var queryLength uint16
err := binary.Read(conn, binary.BigEndian, &queryLength)
if err != nil {
return err
}
if queryLength == 0 {
return dns.RCodeFormatError
}
buffer := buf.NewSize(int(queryLength))
defer buffer.Release()
_, err = buffer.ReadFullFrom(conn, int(queryLength))
if err != nil {
return err
}
var message mDNS.Msg
err = message.Unpack(buffer.Bytes())
if err != nil {
return err
}
metadataInQuery := metadata
go func() error {
response, err := d.router.Exchange(adapter.WithContext(ctx, &metadataInQuery), &message)
if err != nil {
return err
}
responseBuffer := buf.NewPacket()
defer responseBuffer.Release()
responseBuffer.Resize(2, 0)
n, err := response.PackBuffer(responseBuffer.FreeBytes())
if err != nil {
return err
}
responseBuffer.Truncate(len(n))
binary.BigEndian.PutUint16(responseBuffer.ExtendHeader(2), uint16(len(n)))
_, err = conn.Write(responseBuffer.Bytes())
return err
}()
return nil
}
func (d *DNS) NewPacketConnection(ctx context.Context, conn N.PacketConn, metadata adapter.InboundContext) error {
metadata.Destination = M.Socksaddr{}
var reader N.PacketReader = conn
var counters []N.CountFunc
var cachedPackets []*N.PacketBuffer
for {
reader, counters = N.UnwrapCountPacketReader(reader, counters)
if cachedReader, isCached := reader.(N.CachedPacketReader); isCached {
packet := cachedReader.ReadCachedPacket()
if packet != nil {
cachedPackets = append(cachedPackets, packet)
continue
}
}
if readWaiter, created := bufio.CreatePacketReadWaiter(reader); created {
readWaiter.InitializeReadWaiter(N.ReadWaitOptions{})
return d.newPacketConnection(ctx, conn, readWaiter, counters, cachedPackets, metadata)
}
break
}
fastClose, cancel := common.ContextWithCancelCause(ctx)
timeout := canceler.New(fastClose, cancel, C.DNSTimeout)
var group task.Group
group.Append0(func(ctx context.Context) error {
for {
var message mDNS.Msg
var destination M.Socksaddr
var err error
if len(cachedPackets) > 0 {
packet := cachedPackets[0]
cachedPackets = cachedPackets[1:]
for _, counter := range counters {
counter(int64(packet.Buffer.Len()))
}
err = message.Unpack(packet.Buffer.Bytes())
packet.Buffer.Release()
if err != nil {
cancel(err)
return err
}
destination = packet.Destination
} else {
buffer := buf.NewPacket()
destination, err = conn.ReadPacket(buffer)
if err != nil {
buffer.Release()
cancel(err)
return err
}
for _, counter := range counters {
counter(int64(buffer.Len()))
}
err = message.Unpack(buffer.Bytes())
buffer.Release()
if err != nil {
cancel(err)
return err
}
timeout.Update()
}
metadataInQuery := metadata
go func() error {
response, err := d.router.Exchange(adapter.WithContext(ctx, &metadataInQuery), &message)
if err != nil {
cancel(err)
return err
}
timeout.Update()
responseBuffer, err := dns.TruncateDNSMessage(&message, response, 1024)
if err != nil {
cancel(err)
return err
}
err = conn.WritePacket(responseBuffer, destination)
if err != nil {
cancel(err)
}
return err
}()
}
})
group.Cleanup(func() {
conn.Close()
})
return group.Run(fastClose)
}
func (d *DNS) newPacketConnection(ctx context.Context, conn N.PacketConn, readWaiter N.PacketReadWaiter, readCounters []N.CountFunc, cached []*N.PacketBuffer, metadata adapter.InboundContext) error {
ctx = adapter.WithContext(ctx, &metadata)
fastClose, cancel := common.ContextWithCancelCause(ctx)
timeout := canceler.New(fastClose, cancel, C.DNSTimeout)
var group task.Group
group.Append0(func(ctx context.Context) error {
for {
var (
message mDNS.Msg
destination M.Socksaddr
err error
buffer *buf.Buffer
)
if len(cached) > 0 {
packet := cached[0]
cached = cached[1:]
for _, counter := range readCounters {
counter(int64(packet.Buffer.Len()))
}
err = message.Unpack(packet.Buffer.Bytes())
packet.Buffer.Release()
if err != nil {
cancel(err)
return err
}
destination = packet.Destination
} else {
buffer, destination, err = readWaiter.WaitReadPacket()
if err != nil {
cancel(err)
return err
}
for _, counter := range readCounters {
counter(int64(buffer.Len()))
}
err = message.Unpack(buffer.Bytes())
buffer.Release()
if err != nil {
cancel(err)
return err
}
timeout.Update()
}
metadataInQuery := metadata
go func() error {
response, err := d.router.Exchange(adapter.WithContext(ctx, &metadataInQuery), &message)
if err != nil {
cancel(err)
return err
}
timeout.Update()
responseBuffer, err := dns.TruncateDNSMessage(&message, response, 1024)
if err != nil {
cancel(err)
return err
}
err = conn.WritePacket(responseBuffer, destination)
if err != nil {
cancel(err)
}
return err
}()
}
})
group.Cleanup(func() {
conn.Close()
})
return group.Run(fastClose)
}