chore: better keepalive handle

common/net/tcp_keepalive.go

@@ -0,0 +1,23 @@
+package net
+
+import (
+	"net"
+	"runtime"
+	"time"
+)
+
+var (
+	KeepAliveIdle     = 0 * time.Second
+	KeepAliveInterval = 0 * time.Second
+	DisableKeepAlive  = false
+)
+
+func TCPKeepAlive(c net.Conn) {
+	if tcp, ok := c.(*net.TCPConn); ok {
+		if runtime.GOOS == "android" || DisableKeepAlive {
+			_ = tcp.SetKeepAlive(false)
+		} else {
+			tcpKeepAlive(tcp)
+		}
+	}
+}

common/net/tcp_keepalive_go122.go

@@ -4,9 +4,7 @@ package net
 
 import "net"
 
-func TCPKeepAlive(c net.Conn) {
-	if tcp, ok := c.(*net.TCPConn); ok {
-		_ = tcp.SetKeepAlive(true)
-		_ = tcp.SetKeepAlivePeriod(KeepAliveInterval)
-	}
+func tcpKeepAlive(tcp *net.TCPConn) {
+	_ = tcp.SetKeepAlive(true)
+	_ = tcp.SetKeepAlivePeriod(KeepAliveInterval)
 }

common/net/tcp_keepalive_go123.go

@@ -4,12 +4,16 @@ package net
 
 import "net"
 
-func TCPKeepAlive(c net.Conn) {
-	if tcp, ok := c.(*net.TCPConn); ok {
-		_ = tcp.SetKeepAliveConfig(net.KeepAliveConfig{
-			Enable:   true,
-			Idle:     KeepAliveIdle,
-			Interval: KeepAliveInterval,
-		})
+func tcpKeepAlive(tcp *net.TCPConn) {
+	config := net.KeepAliveConfig{
+		Enable:   true,
+		Idle:     KeepAliveIdle,
+		Interval: KeepAliveInterval,
 	}
+	if !SupportTCPKeepAliveCount() {
+		// it's recommended to set both Idle and Interval to non-negative values in conjunction with a -1
+		// for Count on those old Windows if you intend to customize the TCP keep-alive settings.
+		config.Count = -1
+	}
+	_ = tcp.SetKeepAliveConfig(config)
 }

common/net/tcp_keepalive_go123_unix.go

@@ -0,0 +1,15 @@
+//go:build go1.23 && unix
+
+package net
+
+func SupportTCPKeepAliveIdle() bool {
+	return true
+}
+
+func SupportTCPKeepAliveInterval() bool {
+	return true
+}
+
+func SupportTCPKeepAliveCount() bool {
+	return true
+}

common/net/tcp_keepalive_go123_windows.go

@@ -0,0 +1,63 @@
+//go:build go1.23 && windows
+
+// copy and modify from golang1.23's internal/syscall/windows/version_windows.go
+
+package net
+
+import (
+	"errors"
+	"sync"
+	"syscall"
+
+	"github.com/metacubex/mihomo/constant/features"
+
+	"golang.org/x/sys/windows"
+)
+
+var (
+	supportTCPKeepAliveIdle     bool
+	supportTCPKeepAliveInterval bool
+	supportTCPKeepAliveCount    bool
+)
+
+var initTCPKeepAlive = sync.OnceFunc(func() {
+	s, err := windows.WSASocket(syscall.AF_INET, syscall.SOCK_STREAM, syscall.IPPROTO_TCP, nil, 0, windows.WSA_FLAG_NO_HANDLE_INHERIT)
+	if err != nil {
+		// Fallback to checking the Windows version.
+		major, build := features.WindowsMajorVersion, features.WindowsBuildNumber
+		supportTCPKeepAliveIdle = major >= 10 && build >= 16299
+		supportTCPKeepAliveInterval = major >= 10 && build >= 16299
+		supportTCPKeepAliveCount = major >= 10 && build >= 15063
+		return
+	}
+	defer windows.Closesocket(s)
+	var optSupported = func(opt int) bool {
+		err := windows.SetsockoptInt(s, syscall.IPPROTO_TCP, opt, 1)
+		return !errors.Is(err, syscall.WSAENOPROTOOPT)
+	}
+	supportTCPKeepAliveIdle = optSupported(windows.TCP_KEEPIDLE)
+	supportTCPKeepAliveInterval = optSupported(windows.TCP_KEEPINTVL)
+	supportTCPKeepAliveCount = optSupported(windows.TCP_KEEPCNT)
+})
+
+// SupportTCPKeepAliveIdle indicates whether TCP_KEEPIDLE is supported.
+// The minimal requirement is Windows 10.0.16299.
+func SupportTCPKeepAliveIdle() bool {
+	initTCPKeepAlive()
+	return supportTCPKeepAliveIdle
+}
+
+// SupportTCPKeepAliveInterval indicates whether TCP_KEEPINTVL is supported.
+// The minimal requirement is Windows 10.0.16299.
+func SupportTCPKeepAliveInterval() bool {
+	initTCPKeepAlive()
+	return supportTCPKeepAliveInterval
+}
+
+// SupportTCPKeepAliveCount indicates whether TCP_KEEPCNT is supported.
+// supports TCP_KEEPCNT.
+// The minimal requirement is Windows 10.0.15063.
+func SupportTCPKeepAliveCount() bool {
+	initTCPKeepAlive()
+	return supportTCPKeepAliveCount
+}

common/net/tcpip.go

@@ -4,12 +4,6 @@ import (
 	"fmt"
 	"net"
 	"strings"
-	"time"
-)
-
-var (
-	KeepAliveIdle     = 0 * time.Second
-	KeepAliveInterval = 0 * time.Second
 )
 
 func SplitNetworkType(s string) (string, string, error) {