chore: decrease direct udp read memory used for no-windows platform

adapter/outbound/base.go

@@ -220,7 +220,7 @@ func NewConn(c net.Conn, a C.ProxyAdapter) C.Conn {
 }
 
 type packetConn struct {
-	net.PacketConn
+	N.EnhancePacketConn
 	chain                   C.Chain
 	adapterName             string
 	connID                  string
@@ -242,15 +242,27 @@ func (c *packetConn) AppendToChains(a C.ProxyAdapter) {
 }
 
 func (c *packetConn) LocalAddr() net.Addr {
-	lAddr := c.PacketConn.LocalAddr()
+	lAddr := c.EnhancePacketConn.LocalAddr()
 	return N.NewCustomAddr(c.adapterName, c.connID, lAddr) // make quic-go's connMultiplexer happy
 }
 
+func (c *packetConn) Upstream() any {
+	return c.EnhancePacketConn
+}
+
+func (c *packetConn) WriterReplaceable() bool {
+	return true
+}
+
+func (c *packetConn) ReaderReplaceable() bool {
+	return true
+}
+
 func newPacketConn(pc net.PacketConn, a C.ProxyAdapter) C.PacketConn {
 	if _, ok := pc.(syscall.Conn); !ok { // exclusion system conn like *net.UDPConn
 		pc = N.NewDeadlinePacketConn(pc) // most conn from outbound can't handle readDeadline correctly
 	}
-	return &packetConn{pc, []string{a.Name()}, a.Name(), utils.NewUUIDV4().String(), parseRemoteDestination(a.Addr())}
+	return &packetConn{N.NewEnhancePacketConn(pc), []string{a.Name()}, a.Name(), utils.NewUUIDV4().String(), parseRemoteDestination(a.Addr())}
 }
 
 func parseRemoteDestination(addr string) string {

adapter/outbound/direct.go

@@ -3,8 +3,6 @@ package outbound
 import (
 	"context"
 	"errors"
-	"net"
-
 	"github.com/Dreamacro/clash/component/dialer"
 	"github.com/Dreamacro/clash/component/resolver"
 	C "github.com/Dreamacro/clash/constant"
@@ -39,11 +37,7 @@ func (d *Direct) ListenPacketContext(ctx context.Context, metadata *C.Metadata,
 	if err != nil {
 		return nil, err
 	}
-	return newPacketConn(&directPacketConn{pc}, d), nil
-}
-
-type directPacketConn struct {
-	net.PacketConn
+	return newPacketConn(pc, d), nil
 }
 
 func NewDirect() *Direct {

common/net/packet.go

@@ -0,0 +1,68 @@
+package net
+
+import (
+	"net"
+
+	"github.com/Dreamacro/clash/common/pool"
+)
+
+type EnhancePacketConn interface {
+	net.PacketConn
+	WaitReadFrom() (data []byte, put func(), addr net.Addr, err error)
+	Upstream() any
+}
+
+func NewEnhancePacketConn(pc net.PacketConn) EnhancePacketConn {
+	if udpConn, isUDPConn := pc.(*net.UDPConn); isUDPConn {
+		return &enhanceUDPConn{UDPConn: udpConn}
+	}
+	return &enhancePacketConn{PacketConn: pc}
+}
+
+type enhancePacketConn struct {
+	net.PacketConn
+}
+
+func (c *enhancePacketConn) WaitReadFrom() (data []byte, put func(), addr net.Addr, err error) {
+	return waitReadFrom(c.PacketConn)
+}
+
+func (c *enhancePacketConn) Upstream() any {
+	return c.PacketConn
+}
+
+func (c *enhancePacketConn) WriterReplaceable() bool {
+	return true
+}
+
+func (c *enhancePacketConn) ReaderReplaceable() bool {
+	return true
+}
+
+func (c *enhanceUDPConn) Upstream() any {
+	return c.UDPConn
+}
+
+func (c *enhanceUDPConn) WriterReplaceable() bool {
+	return true
+}
+
+func (c *enhanceUDPConn) ReaderReplaceable() bool {
+	return true
+}
+
+func waitReadFrom(pc net.PacketConn) (data []byte, put func(), addr net.Addr, err error) {
+	readBuf := pool.Get(pool.UDPBufferSize)
+	put = func() {
+		_ = pool.Put(readBuf)
+	}
+	var readN int
+	readN, addr, err = pc.ReadFrom(readBuf)
+	if readN > 0 {
+		data = readBuf[:readN]
+	} else {
+		put()
+		put = nil
+	}
+	return
+}

common/net/packet_posix.go

@@ -0,0 +1,64 @@
+//go:build !windows
+
+package net
+
+import (
+	"io"
+	"net"
+	"strconv"
+	"syscall"
+
+	"github.com/Dreamacro/clash/common/pool"
+)
+
+type enhanceUDPConn struct {
+	*net.UDPConn
+	rawConn syscall.RawConn
+}
+
+func (c *enhanceUDPConn) WaitReadFrom() (data []byte, put func(), addr net.Addr, err error) {
+	if c.rawConn == nil {
+		c.rawConn, _ = c.UDPConn.SyscallConn()
+	}
+	var readErr error
+	err = c.rawConn.Read(func(fd uintptr) (done bool) {
+		readBuf := pool.Get(pool.UDPBufferSize)
+		put = func() {
+			_ = pool.Put(readBuf)
+		}
+		var readFrom syscall.Sockaddr
+		var readN int
+		readN, _, _, readFrom, readErr = syscall.Recvmsg(int(fd), readBuf, nil, 0)
+		if readN > 0 {
+			data = readBuf[:readN]
+		} else {
+			put()
+			put = nil
+		}
+		if readErr == syscall.EAGAIN {
+			return false
+		}
+		if readFrom != nil {
+			switch from := readFrom.(type) {
+			case *syscall.SockaddrInet4:
+				ip := from.Addr // copy from.Addr; ip escapes, so this line allocates 4 bytes
+				addr = &net.UDPAddr{IP: ip[:], Port: from.Port}
+			case *syscall.SockaddrInet6:
+				ip := from.Addr // copy from.Addr; ip escapes, so this line allocates 16 bytes
+				addr = &net.UDPAddr{IP: ip[:], Port: from.Port, Zone: strconv.FormatInt(int64(from.ZoneId), 10)}
+			}
+		}
+		if readN == 0 {
+			readErr = io.EOF
+		}
+		return true
+	})
+	if err != nil {
+		return
+	}
+	if readErr != nil {
+		err = readErr
+		return
+	}
+	return
+}

common/net/packet_windows.go

@@ -0,0 +1,15 @@
+//go:build windows
+
+package net
+
+import (
+	"net"
+)
+
+type enhanceUDPConn struct {
+	*net.UDPConn
+}
+
+func (c *enhanceUDPConn) WaitReadFrom() (data []byte, put func(), addr net.Addr, err error) {
+	return waitReadFrom(c.UDPConn)
+}

constant/adapters.go

@@ -81,7 +81,7 @@ type Conn interface {
 }
 
 type PacketConn interface {
-	net.PacketConn
+	N.EnhancePacketConn
 	Connection
 	// Deprecate WriteWithMetadata because of remote resolve DNS cause TURN failed
 	// WriteWithMetadata(p []byte, metadata *Metadata) (n int, err error)

tunnel/connection.go

@@ -7,7 +7,6 @@ import (
 	"time"
 
 	N "github.com/Dreamacro/clash/common/net"
-	"github.com/Dreamacro/clash/common/pool"
 	C "github.com/Dreamacro/clash/constant"
 	"github.com/Dreamacro/clash/log"
 )
@@ -27,18 +26,16 @@ func handleUDPToRemote(packet C.UDPPacket, pc C.PacketConn, metadata *C.Metadata
 	return nil
 }
 
-func handleUDPToLocal(packet C.UDPPacket, pc net.PacketConn, key string, oAddr, fAddr netip.Addr) {
-	buf := pool.Get(pool.UDPBufferSize)
+func handleUDPToLocal(packet C.UDPPacket, pc N.EnhancePacketConn, key string, oAddr, fAddr netip.Addr) {
 	defer func() {
 		_ = pc.Close()
 		closeAllLocalCoon(key)
 		natTable.Delete(key)
-		_ = pool.Put(buf)
 	}()
 
 	for {
 		_ = pc.SetReadDeadline(time.Now().Add(udpTimeout))
-		n, from, err := pc.ReadFrom(buf)
+		data, put, from, err := pc.WaitReadFrom()
 		if err != nil {
 			return
 		}
@@ -54,7 +51,8 @@ func handleUDPToLocal(packet C.UDPPacket, pc net.PacketConn, key string, oAddr,
 			}
 		}
 
-		_, err = packet.WriteBack(buf[:n], fromUDPAddr)
+		_, err = packet.WriteBack(data, fromUDPAddr)
+		put()
 		if err != nil {
 			return
 		}

tunnel/statistic/tracker.go

@@ -186,6 +186,16 @@ func (ut *udpTracker) ReadFrom(b []byte) (int, net.Addr, error) {
 	return n, addr, err
 }
 
+func (ut *udpTracker) WaitReadFrom() (data []byte, put func(), addr net.Addr, err error) {
+	data, put, addr, err = ut.PacketConn.WaitReadFrom()
+	download := int64(len(data))
+	if ut.pushToManager {
+		ut.manager.PushDownloaded(download)
+	}
+	ut.DownloadTotal.Add(download)
+	return
+}
+
 func (ut *udpTracker) WriteTo(b []byte, addr net.Addr) (int, error) {
 	n, err := ut.PacketConn.WriteTo(b, addr)
 	upload := int64(n)