refactor: Modular inbounds/outbounds

common/listener/listener.go

@@ -0,0 +1,136 @@
+package listener
+
+import (
+	"context"
+	"net"
+	"sync/atomic"
+
+	"github.com/sagernet/sing-box/adapter"
+	"github.com/sagernet/sing-box/common/settings"
+	"github.com/sagernet/sing-box/option"
+	"github.com/sagernet/sing/common"
+	E "github.com/sagernet/sing/common/exceptions"
+	"github.com/sagernet/sing/common/logger"
+	M "github.com/sagernet/sing/common/metadata"
+	N "github.com/sagernet/sing/common/network"
+)
+
+type Listener struct {
+	ctx                      context.Context
+	logger                   logger.ContextLogger
+	network                  []string
+	listenOptions            option.ListenOptions
+	connHandler              adapter.ConnectionHandlerEx
+	packetHandler            adapter.PacketHandlerEx
+	oobPacketHandler         adapter.OOBPacketHandlerEx
+	threadUnsafePacketWriter bool
+	disablePacketOutput      bool
+	setSystemProxy           bool
+	systemProxySOCKS         bool
+
+	tcpListener          net.Listener
+	systemProxy          settings.SystemProxy
+	udpConn              *net.UDPConn
+	udpAddr              M.Socksaddr
+	packetOutbound       chan *N.PacketBuffer
+	packetOutboundClosed chan struct{}
+	shutdown             atomic.Bool
+}
+
+type Options struct {
+	Context                  context.Context
+	Logger                   logger.ContextLogger
+	Network                  []string
+	Listen                   option.ListenOptions
+	ConnectionHandler        adapter.ConnectionHandlerEx
+	PacketHandler            adapter.PacketHandlerEx
+	OOBPacketHandler         adapter.OOBPacketHandlerEx
+	ThreadUnsafePacketWriter bool
+	DisablePacketOutput      bool
+	SetSystemProxy           bool
+	SystemProxySOCKS         bool
+}
+
+func New(
+	options Options,
+) *Listener {
+	return &Listener{
+		ctx:                      options.Context,
+		logger:                   options.Logger,
+		network:                  options.Network,
+		listenOptions:            options.Listen,
+		connHandler:              options.ConnectionHandler,
+		packetHandler:            options.PacketHandler,
+		oobPacketHandler:         options.OOBPacketHandler,
+		threadUnsafePacketWriter: options.ThreadUnsafePacketWriter,
+		disablePacketOutput:      options.DisablePacketOutput,
+		setSystemProxy:           options.SetSystemProxy,
+		systemProxySOCKS:         options.SystemProxySOCKS,
+	}
+}
+
+func (l *Listener) Start() error {
+	if common.Contains(l.network, N.NetworkTCP) {
+		_, err := l.ListenTCP()
+		if err != nil {
+			return err
+		}
+		go l.loopTCPIn()
+	}
+	if common.Contains(l.network, N.NetworkUDP) {
+		_, err := l.ListenUDP()
+		if err != nil {
+			return err
+		}
+		l.packetOutboundClosed = make(chan struct{})
+		l.packetOutbound = make(chan *N.PacketBuffer, 64)
+		go l.loopUDPIn()
+		if !l.disablePacketOutput {
+			go l.loopUDPOut()
+		}
+	}
+	if l.setSystemProxy {
+		listenPort := M.SocksaddrFromNet(l.tcpListener.Addr()).Port
+		var listenAddrString string
+		listenAddr := l.listenOptions.Listen.Build()
+		if listenAddr.IsUnspecified() {
+			listenAddrString = "127.0.0.1"
+		} else {
+			listenAddrString = listenAddr.String()
+		}
+		systemProxy, err := settings.NewSystemProxy(l.ctx, M.ParseSocksaddrHostPort(listenAddrString, listenPort), l.systemProxySOCKS)
+		if err != nil {
+			return E.Cause(err, "initialize system proxy")
+		}
+		err = systemProxy.Enable()
+		if err != nil {
+			return E.Cause(err, "set system proxy")
+		}
+		l.systemProxy = systemProxy
+	}
+	return nil
+}
+
+func (l *Listener) Close() error {
+	l.shutdown.Store(true)
+	var err error
+	if l.systemProxy != nil && l.systemProxy.IsEnabled() {
+		err = l.systemProxy.Disable()
+	}
+	return E.Errors(err, common.Close(
+		l.tcpListener,
+		common.PtrOrNil(l.udpConn),
+	))
+}
+
+func (l *Listener) TCPListener() net.Listener {
+	return l.tcpListener
+}
+
+func (l *Listener) UDPConn() *net.UDPConn {
+	return l.udpConn
+}
+
+func (l *Listener) ListenOptions() option.ListenOptions {
+	return l.listenOptions
+}

common/listener/listener_go121.go

@@ -0,0 +1,11 @@
+//go:build go1.21
+
+package listener
+
+import "net"
+
+const go121Available = true
+
+func setMultiPathTCP(listenConfig *net.ListenConfig) {
+	listenConfig.SetMultipathTCP(true)
+}

common/listener/listener_go123.go

@@ -0,0 +1,16 @@
+//go:build go1.23
+
+package listener
+
+import (
+	"net"
+	"time"
+)
+
+func setKeepAliveConfig(listener *net.ListenConfig, idle time.Duration, interval time.Duration) {
+	listener.KeepAliveConfig = net.KeepAliveConfig{
+		Enable:   true,
+		Idle:     idle,
+		Interval: interval,
+	}
+}

common/listener/listener_nongo121.go

@@ -0,0 +1,10 @@
+//go:build !go1.21
+
+package listener
+
+import "net"
+
+const go121Available = false
+
+func setMultiPathTCP(listenConfig *net.ListenConfig) {
+}

common/listener/listener_nongo123.go

@@ -0,0 +1,15 @@
+//go:build !go1.23
+
+package listener
+
+import (
+	"net"
+	"time"
+
+	"github.com/sagernet/sing/common/control"
+)
+
+func setKeepAliveConfig(listener *net.ListenConfig, idle time.Duration, interval time.Duration) {
+	listener.KeepAlive = idle
+	listener.Control = control.Append(listener.Control, control.SetKeepAlivePeriod(idle, interval))
+}

common/listener/listener_tcp.go

@@ -0,0 +1,85 @@
+package listener
+
+import (
+	"net"
+	"time"
+
+	"github.com/sagernet/sing-box/adapter"
+	C "github.com/sagernet/sing-box/constant"
+	"github.com/sagernet/sing-box/log"
+	E "github.com/sagernet/sing/common/exceptions"
+	M "github.com/sagernet/sing/common/metadata"
+	N "github.com/sagernet/sing/common/network"
+
+	"github.com/metacubex/tfo-go"
+)
+
+func (l *Listener) ListenTCP() (net.Listener, error) {
+	var err error
+	bindAddr := M.SocksaddrFrom(l.listenOptions.Listen.Build(), l.listenOptions.ListenPort)
+	var tcpListener net.Listener
+	var listenConfig net.ListenConfig
+	if l.listenOptions.TCPKeepAlive >= 0 {
+		keepIdle := time.Duration(l.listenOptions.TCPKeepAlive)
+		if keepIdle == 0 {
+			keepIdle = C.TCPKeepAliveInitial
+		}
+		keepInterval := time.Duration(l.listenOptions.TCPKeepAliveInterval)
+		if keepInterval == 0 {
+			keepInterval = C.TCPKeepAliveInterval
+		}
+		setKeepAliveConfig(&listenConfig, keepIdle, keepInterval)
+	}
+	if l.listenOptions.TCPMultiPath {
+		if !go121Available {
+			return nil, E.New("MultiPath TCP requires go1.21, please recompile your binary.")
+		}
+		setMultiPathTCP(&listenConfig)
+	}
+	if l.listenOptions.TCPFastOpen {
+		var tfoConfig tfo.ListenConfig
+		tfoConfig.ListenConfig = listenConfig
+		tcpListener, err = tfoConfig.Listen(l.ctx, M.NetworkFromNetAddr(N.NetworkTCP, bindAddr.Addr), bindAddr.String())
+	} else {
+		tcpListener, err = listenConfig.Listen(l.ctx, M.NetworkFromNetAddr(N.NetworkTCP, bindAddr.Addr), bindAddr.String())
+	}
+	if err == nil {
+		l.logger.Info("tcp server started at ", tcpListener.Addr())
+	}
+	//nolint:staticcheck
+	if l.listenOptions.ProxyProtocol || l.listenOptions.ProxyProtocolAcceptNoHeader {
+		return nil, E.New("Proxy Protocol is deprecated and removed in sing-box 1.6.0")
+	}
+	l.tcpListener = tcpListener
+	return tcpListener, err
+}
+
+func (l *Listener) loopTCPIn() {
+	tcpListener := l.tcpListener
+	var metadata adapter.InboundContext
+	for {
+		conn, err := tcpListener.Accept()
+		if err != nil {
+			//nolint:staticcheck
+			if netError, isNetError := err.(net.Error); isNetError && netError.Temporary() {
+				l.logger.Error(err)
+				continue
+			}
+			if l.shutdown.Load() && E.IsClosed(err) {
+				return
+			}
+			l.tcpListener.Close()
+			l.logger.Error("tcp listener closed: ", err)
+			continue
+		}
+		//nolint:staticcheck
+		metadata.InboundDetour = l.listenOptions.Detour
+		//nolint:staticcheck
+		metadata.InboundOptions = l.listenOptions.InboundOptions
+		metadata.Source = M.SocksaddrFromNet(conn.RemoteAddr()).Unwrap()
+		metadata.OriginDestination = M.SocksaddrFromNet(conn.LocalAddr()).Unwrap()
+		ctx := log.ContextWithNewID(l.ctx)
+		l.logger.InfoContext(ctx, "inbound connection from ", metadata.Source)
+		go l.connHandler.NewConnectionEx(ctx, conn, metadata, nil)
+	}
+}

common/listener/listener_udp.go

@@ -0,0 +1,153 @@
+package listener
+
+import (
+	"net"
+	"os"
+
+	"github.com/sagernet/sing/common/buf"
+	"github.com/sagernet/sing/common/control"
+	E "github.com/sagernet/sing/common/exceptions"
+	M "github.com/sagernet/sing/common/metadata"
+	N "github.com/sagernet/sing/common/network"
+)
+
+func (l *Listener) ListenUDP() (net.PacketConn, error) {
+	bindAddr := M.SocksaddrFrom(l.listenOptions.Listen.Build(), l.listenOptions.ListenPort)
+	var lc net.ListenConfig
+	var udpFragment bool
+	if l.listenOptions.UDPFragment != nil {
+		udpFragment = *l.listenOptions.UDPFragment
+	} else {
+		udpFragment = l.listenOptions.UDPFragmentDefault
+	}
+	if !udpFragment {
+		lc.Control = control.Append(lc.Control, control.DisableUDPFragment())
+	}
+	udpConn, err := lc.ListenPacket(l.ctx, M.NetworkFromNetAddr(N.NetworkUDP, bindAddr.Addr), bindAddr.String())
+	if err != nil {
+		return nil, err
+	}
+	l.udpConn = udpConn.(*net.UDPConn)
+	l.udpAddr = bindAddr
+	l.logger.Info("udp server started at ", udpConn.LocalAddr())
+	return udpConn, err
+}
+
+func (l *Listener) UDPAddr() M.Socksaddr {
+	return l.udpAddr
+}
+
+func (l *Listener) PacketWriter() N.PacketWriter {
+	return (*packetWriter)(l)
+}
+
+func (l *Listener) loopUDPIn() {
+	defer close(l.packetOutboundClosed)
+	var buffer *buf.Buffer
+	if !l.threadUnsafePacketWriter {
+		buffer = buf.NewPacket()
+		defer buffer.Release()
+		buffer.IncRef()
+		defer buffer.DecRef()
+	}
+	if l.oobPacketHandler != nil {
+		oob := make([]byte, 1024)
+		for {
+			if l.threadUnsafePacketWriter {
+				buffer = buf.NewPacket()
+			} else {
+				buffer.Reset()
+			}
+			n, oobN, _, addr, err := l.udpConn.ReadMsgUDPAddrPort(buffer.FreeBytes(), oob)
+			if err != nil {
+				if l.threadUnsafePacketWriter {
+					buffer.Release()
+				}
+				if l.shutdown.Load() && E.IsClosed(err) {
+					return
+				}
+				l.udpConn.Close()
+				l.logger.Error("udp listener closed: ", err)
+				return
+			}
+			buffer.Truncate(n)
+			l.oobPacketHandler.NewPacketEx(buffer, oob[:oobN], M.SocksaddrFromNetIP(addr).Unwrap())
+		}
+	} else {
+		for {
+			if l.threadUnsafePacketWriter {
+				buffer = buf.NewPacket()
+			} else {
+				buffer.Reset()
+			}
+			n, addr, err := l.udpConn.ReadFromUDPAddrPort(buffer.FreeBytes())
+			if err != nil {
+				if l.threadUnsafePacketWriter {
+					buffer.Release()
+				}
+				if l.shutdown.Load() && E.IsClosed(err) {
+					return
+				}
+				l.udpConn.Close()
+				l.logger.Error("udp listener closed: ", err)
+				return
+			}
+			buffer.Truncate(n)
+			l.packetHandler.NewPacketEx(buffer, M.SocksaddrFromNetIP(addr).Unwrap())
+		}
+	}
+}
+
+func (l *Listener) loopUDPOut() {
+	for {
+		select {
+		case packet := <-l.packetOutbound:
+			destination := packet.Destination.AddrPort()
+			_, err := l.udpConn.WriteToUDPAddrPort(packet.Buffer.Bytes(), destination)
+			packet.Buffer.Release()
+			N.PutPacketBuffer(packet)
+			if err != nil {
+				if l.shutdown.Load() && E.IsClosed(err) {
+					return
+				}
+				l.udpConn.Close()
+				l.logger.Error("udp listener write back: ", destination, ": ", err)
+				return
+			}
+			continue
+		case <-l.packetOutboundClosed:
+		}
+		for {
+			select {
+			case packet := <-l.packetOutbound:
+				packet.Buffer.Release()
+				N.PutPacketBuffer(packet)
+			default:
+				return
+			}
+		}
+	}
+}
+
+type packetWriter Listener
+
+func (w *packetWriter) WritePacket(buffer *buf.Buffer, destination M.Socksaddr) error {
+	packet := N.NewPacketBuffer()
+	packet.Buffer = buffer
+	packet.Destination = destination
+	select {
+	case w.packetOutbound <- packet:
+		return nil
+	default:
+		buffer.Release()
+		N.PutPacketBuffer(packet)
+		if w.shutdown.Load() {
+			return os.ErrClosed
+		}
+		w.logger.Trace("dropped packet to ", destination)
+		return nil
+	}
+}
+
+func (w *packetWriter) WriteIsThreadUnsafe() {
+}