Add TCPKeepAliveIdle in Sockopt option (#1166)

* Add TCP keep alive idle setting

* Add TCP keep alive idle setting: auto generated

* Add TCP keep alive support in Linux

* Add TCP keep alive support in MacOS, FreeBSD

* Add TCP keep alive support in Windows

* fix bug introduced in adding tcp keep alive adjustment

* embed macOS const to avoid platform inconsistency

* embed macOS const to avoid platform inconsistency(again)

* add TCP Keep Alive support in config

* use sys/unix instead of syscall

Suggestion from:
https://github.com/v2fly/v2ray-core/pull/1395#issuecomment-974761647

* use sys/unix instead of syscall

Suggestion from:
https://github.com/v2fly/v2ray-core/pull/1395#issuecomment-974761647

* Separate TcpKeepAliveIdle and TcpKeepAliveInterval check logic

* Disable tcp keepAlive when TcpKeepAliveIdle < 0 and  TcpKeepAliveInterval <= 0

Co-authored-by: xqzr <34030394+xqzr@users.noreply.github.com>

Co-authored-by: ValdikSS <iam@valdikss.org.ru>
Co-authored-by: Shelikhoo <xiaokangwang@outlook.com>
Co-authored-by: xqzr <34030394+xqzr@users.noreply.github.com>

infra/conf/transport_internet.go

@@ -532,6 +532,7 @@ type SocketConfig struct {
 	DomainStrategy       string      `json:"domainStrategy"`
 	DialerProxy          string      `json:"dialerProxy"`
 	TCPKeepAliveInterval int32       `json:"tcpKeepAliveInterval"`
+	TCPKeepAliveIdle     int32       `json:"tcpKeepAliveIdle"`
 }
 
 // Build implements Buildable.
@@ -579,6 +580,7 @@ func (c *SocketConfig) Build() (*internet.SocketConfig, error) {
 		AcceptProxyProtocol:  c.AcceptProxyProtocol,
 		DialerProxy:          c.DialerProxy,
 		TcpKeepAliveInterval: c.TCPKeepAliveInterval,
+		TcpKeepAliveIdle:     c.TCPKeepAliveIdle,
 	}, nil
 }
 

transport/internet/config.pb.go

@@ -1,6 +1,6 @@
 // Code generated by protoc-gen-go. DO NOT EDIT.
 // versions:
-// 	protoc-gen-go v1.27.1
+// 	protoc-gen-go v1.28.1
 // 	protoc        v3.18.0
 // source: transport/internet/config.proto
 
@@ -423,6 +423,7 @@ type SocketConfig struct {
 	DomainStrategy             DomainStrategy `protobuf:"varint,8,opt,name=domain_strategy,json=domainStrategy,proto3,enum=xray.transport.internet.DomainStrategy" json:"domain_strategy,omitempty"`
 	DialerProxy                string         `protobuf:"bytes,9,opt,name=dialer_proxy,json=dialerProxy,proto3" json:"dialer_proxy,omitempty"`
 	TcpKeepAliveInterval       int32          `protobuf:"varint,10,opt,name=tcp_keep_alive_interval,json=tcpKeepAliveInterval,proto3" json:"tcp_keep_alive_interval,omitempty"`
+	TcpKeepAliveIdle           int32          `protobuf:"varint,11,opt,name=tcp_keep_alive_idle,json=tcpKeepAliveIdle,proto3" json:"tcp_keep_alive_idle,omitempty"`
 }
 
 func (x *SocketConfig) Reset() {
@@ -527,6 +528,13 @@ func (x *SocketConfig) GetTcpKeepAliveInterval() int32 {
 	return 0
 }
 
+func (x *SocketConfig) GetTcpKeepAliveIdle() int32 {
+	if x != nil {
+		return x.TcpKeepAliveIdle
+	}
+	return 0
+}
+
 var File_transport_internet_config_proto protoreflect.FileDescriptor
 
 var file_transport_internet_config_proto_rawDesc = []byte{
@@ -579,7 +587,7 @@ var file_transport_internet_config_proto_rawDesc = []byte{
 	0x12, 0x30, 0x0a, 0x13, 0x74, 0x72, 0x61, 0x6e, 0x73, 0x70, 0x6f, 0x72, 0x74, 0x4c, 0x61, 0x79,
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+	0x78, 0x79, 0x22, 0xc1, 0x04, 0x0a, 0x0c, 0x53, 0x6f, 0x63, 0x6b, 0x65, 0x74, 0x43, 0x6f, 0x6e,
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@@ -609,27 +617,30 @@ var file_transport_internet_config_proto_rawDesc = []byte{
 	0x35, 0x0a, 0x17, 0x74, 0x63, 0x70, 0x5f, 0x6b, 0x65, 0x65, 0x70, 0x5f, 0x61, 0x6c, 0x69, 0x76,
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+	0x70, 0x72, 0x6f, 0x74, 0x6f, 0x33,
 }
 
 var (

transport/internet/config.proto

@@ -94,4 +94,6 @@ message SocketConfig {
   string dialer_proxy = 9;
 
   int32 tcp_keep_alive_interval = 10;
+
+  int32 tcp_keep_alive_idle = 11;
 }

transport/internet/sockopt_darwin.go

@@ -1,16 +1,16 @@
 package internet
 
 import (
-	"syscall"
+	"golang.org/x/sys/unix"
 )
 
 const (
-	// TCP_FASTOPEN is the socket option on darwin for TCP fast open.
-	TCP_FASTOPEN = 0x105
 	// TCP_FASTOPEN_SERVER is the value to enable TCP fast open on darwin for server connections.
 	TCP_FASTOPEN_SERVER = 0x01
 	// TCP_FASTOPEN_CLIENT is the value to enable TCP fast open on darwin for client connections.
-	TCP_FASTOPEN_CLIENT = 0x02
+	TCP_FASTOPEN_CLIENT = 0x02 // nolint: revive,stylecheck
+	// syscall.TCP_KEEPINTVL is missing on some darwin architectures.
+	sysTCP_KEEPINTVL = 0x101 // nolint: revive,stylecheck
 )
 
 func applyOutboundSocketOptions(network string, address string, fd uintptr, config *SocketConfig) error {
@@ -20,10 +20,30 @@ func applyOutboundSocketOptions(network string, address string, fd uintptr, conf
 			tfo = TCP_FASTOPEN_CLIENT
 		}
 		if tfo >= 0 {
-			if err := syscall.SetsockoptInt(int(fd), syscall.IPPROTO_TCP, TCP_FASTOPEN, tfo); err != nil {
+			if err := unix.SetsockoptInt(int(fd), unix.IPPROTO_TCP, unix.TCP_FASTOPEN, tfo); err != nil {
 				return err
 			}
 		}
+
+		if config.TcpKeepAliveIdle > 0 || config.TcpKeepAliveInterval > 0 {
+			if config.TcpKeepAliveIdle > 0 {
+				if err := unix.SetsockoptInt(int(fd), unix.IPPROTO_TCP, unix.TCP_KEEPALIVE, int(config.TcpKeepAliveInterval)); err != nil {
+					return newError("failed to set TCP_KEEPINTVL", err)
+				}
+			}
+			if config.TcpKeepAliveInterval > 0 {
+				if err := unix.SetsockoptInt(int(fd), unix.IPPROTO_TCP, sysTCP_KEEPINTVL, int(config.TcpKeepAliveIdle)); err != nil {
+					return newError("failed to set TCP_KEEPIDLE", err)
+				}
+			}
+			if err := unix.SetsockoptInt(int(fd), unix.SOL_SOCKET, unix.SO_KEEPALIVE, 1); err != nil {
+				return newError("failed to set SO_KEEPALIVE", err)
+			}
+		} else if config.TcpKeepAliveInterval < 0 || config.TcpKeepAliveIdle < 0 {
+			if err := unix.SetsockoptInt(int(fd), unix.SOL_SOCKET, unix.SO_KEEPALIVE, 0); err != nil {
+				return newError("failed to unset SO_KEEPALIVE", err)
+			}
+		}
 	}
 
 	return nil
@@ -36,10 +56,29 @@ func applyInboundSocketOptions(network string, fd uintptr, config *SocketConfig)
 			tfo = TCP_FASTOPEN_SERVER
 		}
 		if tfo >= 0 {
-			if err := syscall.SetsockoptInt(int(fd), syscall.IPPROTO_TCP, TCP_FASTOPEN, tfo); err != nil {
+			if err := unix.SetsockoptInt(int(fd), unix.IPPROTO_TCP, unix.TCP_FASTOPEN, tfo); err != nil {
 				return err
 			}
 		}
+		if config.TcpKeepAliveIdle > 0 || config.TcpKeepAliveInterval > 0 {
+			if config.TcpKeepAliveIdle > 0 {
+				if err := unix.SetsockoptInt(int(fd), unix.IPPROTO_TCP, unix.TCP_KEEPALIVE, int(config.TcpKeepAliveInterval)); err != nil {
+					return newError("failed to set TCP_KEEPINTVL", err)
+				}
+			}
+			if config.TcpKeepAliveInterval > 0 {
+				if err := unix.SetsockoptInt(int(fd), unix.IPPROTO_TCP, sysTCP_KEEPINTVL, int(config.TcpKeepAliveIdle)); err != nil {
+					return newError("failed to set TCP_KEEPIDLE", err)
+				}
+			}
+			if err := unix.SetsockoptInt(int(fd), unix.SOL_SOCKET, unix.SO_KEEPALIVE, 1); err != nil {
+				return newError("failed to set SO_KEEPALIVE", err)
+			}
+		} else if config.TcpKeepAliveInterval < 0 || config.TcpKeepAliveIdle < 0 {
+			if err := unix.SetsockoptInt(int(fd), unix.SOL_SOCKET, unix.SO_KEEPALIVE, 0); err != nil {
+				return newError("failed to unset SO_KEEPALIVE", err)
+			}
+		}
 	}
 
 	return nil

transport/internet/sockopt_freebsd.go

@@ -140,6 +140,25 @@ func applyOutboundSocketOptions(network string, address string, fd uintptr, conf
 				return newError("failed to set TCP_FASTOPEN_CONNECT=", tfo).Base(err)
 			}
 		}
+		if config.TcpKeepAliveIdle > 0 || config.TcpKeepAliveInterval > 0 {
+			if config.TcpKeepAliveIdle > 0 {
+				if err := syscall.SetsockoptInt(int(fd), syscall.IPPROTO_TCP, syscall.TCP_KEEPIDLE, int(config.TcpKeepAliveIdle)); err != nil {
+					return newError("failed to set TCP_KEEPIDLE", err)
+				}
+			}
+			if config.TcpKeepAliveInterval > 0 {
+				if err := syscall.SetsockoptInt(int(fd), syscall.IPPROTO_TCP, syscall.TCP_KEEPINTVL, int(config.TcpKeepAliveInterval)); err != nil {
+					return newError("failed to set TCP_KEEPINTVL", err)
+				}
+			}
+			if err := syscall.SetsockoptInt(int(fd), syscall.SOL_SOCKET, syscall.SO_KEEPALIVE, 1); err != nil {
+				return newError("failed to set SO_KEEPALIVE", err)
+			}
+		} else if config.TcpKeepAliveInterval < 0 || config.TcpKeepAliveIdle < 0 {
+			if err := syscall.SetsockoptInt(int(fd), syscall.SOL_SOCKET, syscall.SO_KEEPALIVE, 0); err != nil {
+				return newError("failed to unset SO_KEEPALIVE", err)
+			}
+		}
 	}
 
 	if config.Tproxy.IsEnabled() {
@@ -170,6 +189,25 @@ func applyInboundSocketOptions(network string, fd uintptr, config *SocketConfig)
 				return newError("failed to set TCP_FASTOPEN=", tfo).Base(err)
 			}
 		}
+		if config.TcpKeepAliveIdle > 0 || config.TcpKeepAliveInterval > 0 {
+			if config.TcpKeepAliveIdle > 0 {
+				if err := syscall.SetsockoptInt(int(fd), syscall.IPPROTO_TCP, syscall.TCP_KEEPIDLE, int(config.TcpKeepAliveIdle)); err != nil {
+					return newError("failed to set TCP_KEEPIDLE", err)
+				}
+			}
+			if config.TcpKeepAliveInterval > 0 {
+				if err := syscall.SetsockoptInt(int(fd), syscall.IPPROTO_TCP, syscall.TCP_KEEPINTVL, int(config.TcpKeepAliveInterval)); err != nil {
+					return newError("failed to set TCP_KEEPINTVL", err)
+				}
+			}
+			if err := syscall.SetsockoptInt(int(fd), syscall.SOL_SOCKET, syscall.SO_KEEPALIVE, 1); err != nil {
+				return newError("failed to set SO_KEEPALIVE", err)
+			}
+		} else if config.TcpKeepAliveInterval < 0 || config.TcpKeepAliveIdle < 0 {
+			if err := syscall.SetsockoptInt(int(fd), syscall.SOL_SOCKET, syscall.SO_KEEPALIVE, 0); err != nil {
+				return newError("failed to unset SO_KEEPALIVE", err)
+			}
+		}
 	}
 
 	if config.Tproxy.IsEnabled() {

transport/internet/sockopt_linux.go

@@ -58,9 +58,23 @@ func applyOutboundSocketOptions(network string, address string, fd uintptr, conf
 			}
 		}
 
-		if config.TcpKeepAliveInterval != 0 {
+		if config.TcpKeepAliveInterval > 0 || config.TcpKeepAliveIdle > 0 {
-			if err := syscall.SetsockoptInt(int(fd), syscall.IPPROTO_TCP, syscall.TCP_KEEPINTVL, int(config.TcpKeepAliveInterval)); err != nil {
+			if config.TcpKeepAliveInterval > 0 {
-				return newError("failed to set TCP_KEEPINTVL", err)
+				if err := syscall.SetsockoptInt(int(fd), syscall.IPPROTO_TCP, syscall.TCP_KEEPINTVL, int(config.TcpKeepAliveInterval)); err != nil {
+					return newError("failed to set TCP_KEEPINTVL", err)
+				}
+			}
+			if config.TcpKeepAliveIdle > 0 {
+				if err := syscall.SetsockoptInt(int(fd), syscall.IPPROTO_TCP, syscall.TCP_KEEPIDLE, int(config.TcpKeepAliveIdle)); err != nil {
+					return newError("failed to set TCP_KEEPIDLE", err)
+				}
+			}
+			if err := syscall.SetsockoptInt(int(fd), syscall.SOL_SOCKET, syscall.SO_KEEPALIVE, 1); err != nil {
+				return newError("failed to set SO_KEEPALIVE", err)
+			}
+		} else if config.TcpKeepAliveInterval < 0 || config.TcpKeepAliveIdle < 0 {
+			if err := syscall.SetsockoptInt(int(fd), syscall.SOL_SOCKET, syscall.SO_KEEPALIVE, 0); err != nil {
+				return newError("failed to unset SO_KEEPALIVE", err)
 			}
 		}
 	}
@@ -88,9 +102,23 @@ func applyInboundSocketOptions(network string, fd uintptr, config *SocketConfig)
 			}
 		}
 
-		if config.TcpKeepAliveInterval != 0 {
+		if config.TcpKeepAliveInterval > 0 || config.TcpKeepAliveIdle > 0 {
-			if err := syscall.SetsockoptInt(int(fd), syscall.IPPROTO_TCP, syscall.TCP_KEEPINTVL, int(config.TcpKeepAliveInterval)); err != nil {
+			if config.TcpKeepAliveInterval > 0 {
-				return newError("failed to set TCP_KEEPINTVL", err)
+				if err := syscall.SetsockoptInt(int(fd), syscall.IPPROTO_TCP, syscall.TCP_KEEPINTVL, int(config.TcpKeepAliveInterval)); err != nil {
+					return newError("failed to set TCP_KEEPINTVL", err)
+				}
+			}
+			if config.TcpKeepAliveIdle > 0 {
+				if err := syscall.SetsockoptInt(int(fd), syscall.IPPROTO_TCP, syscall.TCP_KEEPIDLE, int(config.TcpKeepAliveIdle)); err != nil {
+					return newError("failed to set TCP_KEEPIDLE", err)
+				}
+			}
+			if err := syscall.SetsockoptInt(int(fd), syscall.SOL_SOCKET, syscall.SO_KEEPALIVE, 1); err != nil {
+				return newError("failed to set SO_KEEPALIVE", err)
+			}
+		} else if config.TcpKeepAliveInterval < 0 || config.TcpKeepAliveIdle < 0 {
+			if err := syscall.SetsockoptInt(int(fd), syscall.SOL_SOCKET, syscall.SO_KEEPALIVE, 0); err != nil {
+				return newError("failed to unset SO_KEEPALIVE", err)
 			}
 		}
 	}

transport/internet/sockopt_windows.go

@@ -25,6 +25,15 @@ func applyOutboundSocketOptions(network string, address string, fd uintptr, conf
 		if err := setTFO(syscall.Handle(fd), config.ParseTFOValue()); err != nil {
 			return err
 		}
+		if config.TcpKeepAliveIdle > 0 {
+			if err := syscall.SetsockoptInt(syscall.Handle(fd), syscall.SOL_SOCKET, syscall.SO_KEEPALIVE, 1); err != nil {
+				return newError("failed to set SO_KEEPALIVE", err)
+			}
+		} else if config.TcpKeepAliveIdle < 0 {
+			if err := syscall.SetsockoptInt(syscall.Handle(fd), syscall.SOL_SOCKET, syscall.SO_KEEPALIVE, 0); err != nil {
+				return newError("failed to unset SO_KEEPALIVE", err)
+			}
+		}
 	}
 
 	return nil
@@ -35,6 +44,15 @@ func applyInboundSocketOptions(network string, fd uintptr, config *SocketConfig)
 		if err := setTFO(syscall.Handle(fd), config.ParseTFOValue()); err != nil {
 			return err
 		}
+		if config.TcpKeepAliveIdle > 0 {
+			if err := syscall.SetsockoptInt(syscall.Handle(fd), syscall.SOL_SOCKET, syscall.SO_KEEPALIVE, 1); err != nil {
+				return newError("failed to set SO_KEEPALIVE", err)
+			}
+		} else if config.TcpKeepAliveIdle < 0 {
+			if err := syscall.SetsockoptInt(syscall.Handle(fd), syscall.SOL_SOCKET, syscall.SO_KEEPALIVE, 0); err != nil {
+				return newError("failed to unset SO_KEEPALIVE", err)
+			}
+		}
 	}
 
 	return nil

transport/internet/system_dialer.go

@@ -69,10 +69,14 @@ func (d *DefaultSystemDialer) Dial(ctx context.Context, src net.Address, dest ne
 			Dest: destAddr,
 		}, nil
 	}
-
+	goStdKeepAlive := time.Duration(0)
+	if sockopt != nil && sockopt.TcpKeepAliveIdle != 0 {
+		goStdKeepAlive = time.Duration(-1)
+	}
 	dialer := &net.Dialer{
 		Timeout:   time.Second * 16,
 		LocalAddr: resolveSrcAddr(dest.Network, src),
+		KeepAlive: goStdKeepAlive,
 	}
 
 	if sockopt != nil || len(d.controllers) > 0 {

transport/internet/system_listener.go

@@ -7,6 +7,7 @@ import (
 	"strconv"
 	"strings"
 	"syscall"
+	"time"
 
 	"github.com/pires/go-proxyproto"
 	"github.com/xtls/xray-core/common/net"
@@ -50,6 +51,9 @@ func (dl *DefaultListener) Listen(ctx context.Context, addr net.Addr, sockopt *S
 		network = addr.Network()
 		address = addr.String()
 		lc.Control = getControlFunc(ctx, sockopt, dl.controllers)
+		if sockopt != nil && sockopt.TcpKeepAliveIdle != 0 {
+			lc.KeepAlive = time.Duration(-1)
+		}
 	case *net.UnixAddr:
 		lc.Control = nil
 		network = addr.Network()