chore: share RelayDnsPacket function code

adapter/outbound/dns.go

@@ -4,7 +4,6 @@ import (
 	"context"
 	"fmt"
 	"net"
-	"net/netip"
 	"time"
 
 	"github.com/metacubex/mihomo/common/pool"
@@ -12,8 +11,6 @@ import (
 	"github.com/metacubex/mihomo/component/resolver"
 	C "github.com/metacubex/mihomo/constant"
 	"github.com/metacubex/mihomo/log"
-
-	D "github.com/miekg/dns"
 )
 
 type Dns struct {
@@ -79,12 +76,12 @@ func (d *dnsPacketConn) ReadFrom(p []byte) (n int, addr net.Addr, err error) {
 }
 
 func (d *dnsPacketConn) WriteTo(p []byte, addr net.Addr) (n int, err error) {
-	ctx, cancel := context.WithTimeout(d.ctx, time.Second*5)
+	ctx, cancel := context.WithTimeout(d.ctx, resolver.DefaultDnsRelayTimeout)
 	defer cancel()
 
-	buf := pool.Get(2048)
+	buf := pool.Get(resolver.SafeDnsPacketSize)
 	put := func() { _ = pool.Put(buf) }
-	buf, err = RelayDnsPacket(ctx, p, buf)
+	buf, err = resolver.RelayDnsPacket(ctx, p, buf)
 	if err != nil {
 		put()
 		return 0, err
@@ -110,7 +107,11 @@ func (d *dnsPacketConn) Close() error {
 }
 
 func (*dnsPacketConn) LocalAddr() net.Addr {
-	return net.UDPAddrFromAddrPort(netip.MustParseAddrPort("127.0.0.1:53"))
+	return &net.UDPAddr{
+		IP:   net.IPv4(127, 0, 0, 1),
+		Port: 53,
+		Zone: "",
+	}
 }
 
 func (*dnsPacketConn) SetDeadline(t time.Time) error {
@@ -139,22 +140,3 @@ func NewDnsWithOption(option DnsOption) *Dns {
 		},
 	}
 }
-
-// copied from listener/sing_mux/dns.go
-func RelayDnsPacket(ctx context.Context, payload []byte, target []byte) ([]byte, error) {
-	msg := &D.Msg{}
-	if err := msg.Unpack(payload); err != nil {
-		return nil, err
-	}
-
-	r, err := resolver.ServeMsg(ctx, msg)
-	if err != nil {
-		m := new(D.Msg)
-		m.SetRcode(msg, D.RcodeServerFailure)
-		return m.PackBuffer(target)
-	}
-
-	r.SetRcode(msg, r.Rcode)
-	r.Compress = true
-	return r.PackBuffer(target)
-}

component/resolver/relay.go

@@ -0,0 +1,88 @@
+package resolver
+
+import (
+	"context"
+	"encoding/binary"
+	"io"
+	"net"
+	"time"
+
+	"github.com/metacubex/mihomo/common/pool"
+
+	D "github.com/miekg/dns"
+)
+
+const DefaultDnsReadTimeout = time.Second * 10
+const DefaultDnsRelayTimeout = time.Second * 5
+
+const SafeDnsPacketSize = 2 * 1024 // safe size which is 1232 from https://dnsflagday.net/2020/, so 2048 is enough
+
+func RelayDnsConn(ctx context.Context, conn net.Conn) error {
+	buff := pool.Get(pool.UDPBufferSize)
+	defer func() {
+		_ = pool.Put(buff)
+		_ = conn.Close()
+	}()
+	for {
+		if conn.SetReadDeadline(time.Now().Add(DefaultDnsReadTimeout)) != nil {
+			break
+		}
+
+		length := uint16(0)
+		if err := binary.Read(conn, binary.BigEndian, &length); err != nil {
+			break
+		}
+
+		if int(length) > len(buff) {
+			break
+		}
+
+		n, err := io.ReadFull(conn, buff[:length])
+		if err != nil {
+			break
+		}
+
+		err = func() error {
+			ctx, cancel := context.WithTimeout(ctx, DefaultDnsRelayTimeout)
+			defer cancel()
+			inData := buff[:n]
+			msg, err := RelayDnsPacket(ctx, inData, buff)
+			if err != nil {
+				return err
+			}
+
+			err = binary.Write(conn, binary.BigEndian, uint16(len(msg)))
+			if err != nil {
+				return err
+			}
+
+			_, err = conn.Write(msg)
+			if err != nil {
+				return err
+			}
+			return nil
+		}()
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func RelayDnsPacket(ctx context.Context, payload []byte, target []byte) ([]byte, error) {
+	msg := &D.Msg{}
+	if err := msg.Unpack(payload); err != nil {
+		return nil, err
+	}
+
+	r, err := ServeMsg(ctx, msg)
+	if err != nil {
+		m := new(D.Msg)
+		m.SetRcode(msg, D.RcodeServerFailure)
+		return m.PackBuffer(target)
+	}
+
+	r.SetRcode(msg, r.Rcode)
+	r.Compress = true
+	return r.PackBuffer(target)
+}

listener/sing_tun/dns.go

@@ -2,29 +2,21 @@ package sing_tun
 
 import (
 	"context"
-	"encoding/binary"
-	"io"
 	"net"
 	"net/netip"
 	"sync"
 	"time"
 
-	"github.com/metacubex/mihomo/common/pool"
 	"github.com/metacubex/mihomo/component/resolver"
 	"github.com/metacubex/mihomo/listener/sing"
 	"github.com/metacubex/mihomo/log"
 
-	D "github.com/miekg/dns"
-
 	"github.com/sagernet/sing/common/buf"
 	"github.com/sagernet/sing/common/bufio"
 	M "github.com/sagernet/sing/common/metadata"
 	"github.com/sagernet/sing/common/network"
 )
 
-const DefaultDnsReadTimeout = time.Second * 10
-const DefaultDnsRelayTimeout = time.Second * 5
-
 type ListenerHandler struct {
 	*sing.ListenerHandler
 	DnsAdds []netip.AddrPort
@@ -45,61 +37,11 @@ func (h *ListenerHandler) ShouldHijackDns(targetAddr netip.AddrPort) bool {
 func (h *ListenerHandler) NewConnection(ctx context.Context, conn net.Conn, metadata M.Metadata) error {
 	if h.ShouldHijackDns(metadata.Destination.AddrPort()) {
 		log.Debugln("[DNS] hijack tcp:%s", metadata.Destination.String())
-		buff := pool.Get(pool.UDPBufferSize)
-		defer func() {
-			_ = pool.Put(buff)
-			_ = conn.Close()
-		}()
-		for {
-			if conn.SetReadDeadline(time.Now().Add(DefaultDnsReadTimeout)) != nil {
-				break
-			}
-
-			length := uint16(0)
-			if err := binary.Read(conn, binary.BigEndian, &length); err != nil {
-				break
-			}
-
-			if int(length) > len(buff) {
-				break
-			}
-
-			n, err := io.ReadFull(conn, buff[:length])
-			if err != nil {
-				break
-			}
-
-			err = func() error {
-				ctx, cancel := context.WithTimeout(ctx, DefaultDnsRelayTimeout)
-				defer cancel()
-				inData := buff[:n]
-				msg, err := RelayDnsPacket(ctx, inData, buff)
-				if err != nil {
-					return err
-				}
-
-				err = binary.Write(conn, binary.BigEndian, uint16(len(msg)))
-				if err != nil {
-					return err
-				}
-
-				_, err = conn.Write(msg)
-				if err != nil {
-					return err
-				}
-				return nil
-			}()
-			if err != nil {
-				return err
-			}
-		}
-		return nil
+		return resolver.RelayDnsConn(ctx, conn)
 	}
 	return h.ListenerHandler.NewConnection(ctx, conn, metadata)
 }
 
-const SafeDnsPacketSize = 2 * 1024 // safe size which is 1232 from https://dnsflagday.net/2020/, so 2048 is enough
-
 func (h *ListenerHandler) NewPacketConnection(ctx context.Context, conn network.PacketConn, metadata M.Metadata) error {
 	if h.ShouldHijackDns(metadata.Destination.AddrPort()) {
 		log.Debugln("[DNS] hijack udp:%s from %s", metadata.Destination.String(), metadata.Source.String())
@@ -114,7 +56,7 @@ func (h *ListenerHandler) NewPacketConnection(ctx context.Context, conn network.
 		rwOptions := network.ReadWaitOptions{
 			FrontHeadroom: network.CalculateFrontHeadroom(conn),
 			RearHeadroom:  network.CalculateRearHeadroom(conn),
-			MTU:           SafeDnsPacketSize,
+			MTU:           resolver.SafeDnsPacketSize,
 		}
 		readWaiter, isReadWaiter := bufio.CreatePacketReadWaiter(conn)
 		if isReadWaiter {
@@ -126,7 +68,7 @@ func (h *ListenerHandler) NewPacketConnection(ctx context.Context, conn network.
 				dest     M.Socksaddr
 				err      error
 			)
-			_ = conn.SetReadDeadline(time.Now().Add(DefaultDnsReadTimeout))
+			_ = conn.SetReadDeadline(time.Now().Add(resolver.DefaultDnsReadTimeout))
 			readBuff = nil // clear last loop status, avoid repeat release
 			if isReadWaiter {
 				readBuff, dest, err = readWaiter.WaitReadPacket()
@@ -147,15 +89,15 @@ func (h *ListenerHandler) NewPacketConnection(ctx context.Context, conn network.
 				return err
 			}
 			go func() {
-				ctx, cancel := context.WithTimeout(ctx, DefaultDnsRelayTimeout)
+				ctx, cancel := context.WithTimeout(ctx, resolver.DefaultDnsRelayTimeout)
 				defer cancel()
 				inData := readBuff.Bytes()
 				writeBuff := readBuff
 				writeBuff.Resize(writeBuff.Start(), 0)
-				if len(writeBuff.FreeBytes()) < SafeDnsPacketSize { // only create a new buffer when space don't enough
+				if len(writeBuff.FreeBytes()) < resolver.SafeDnsPacketSize { // only create a new buffer when space don't enough
 					writeBuff = rwOptions.NewPacketBuffer()
 				}
-				msg, err := RelayDnsPacket(ctx, inData, writeBuff.FreeBytes())
+				msg, err := resolver.RelayDnsPacket(ctx, inData, writeBuff.FreeBytes())
 				if writeBuff != readBuff {
 					readBuff.Release()
 				}
@@ -182,21 +124,3 @@ func (h *ListenerHandler) NewPacketConnection(ctx context.Context, conn network.
 	}
 	return h.ListenerHandler.NewPacketConnection(ctx, conn, metadata)
 }
-
-func RelayDnsPacket(ctx context.Context, payload []byte, target []byte) ([]byte, error) {
-	msg := &D.Msg{}
-	if err := msg.Unpack(payload); err != nil {
-		return nil, err
-	}
-
-	r, err := resolver.ServeMsg(ctx, msg)
-	if err != nil {
-		m := new(D.Msg)
-		m.SetRcode(msg, D.RcodeServerFailure)
-		return m.PackBuffer(target)
-	}
-
-	r.SetRcode(msg, r.Rcode)
-	r.Compress = true
-	return r.PackBuffer(target)
-}