client: set TCP_USER_TIMEOUT socket option for linux

Signed-off-by: zhangzujian <zhangzujian.7@gmail.com>

Author: zhangzujian

client/client.go

@@ -353,6 +353,12 @@ func (o *ovsdbClient) tryEndpoint(ctx context.Context, u *url.URL) (string, erro
 		return "", fmt.Errorf("failed to open connection: %w", err)
 	}
 
+	if o.options.timeout != 0 {
+		if err = setTCPUserTimeout(c, o.options.timeout); err != nil {
+			return "", fmt.Errorf("failed to set TCP_USER_TIMEOUT: %v", err)
+		}
+	}
+
 	o.createRPC2Client(c)
 
 	serverDBNames, err := o.listDbs(ctx)

client/syscall_linux.go

@@ -0,0 +1,36 @@
+//go:build linux
+// +build linux
+
+// from https://github.com/grpc/grpc-go/internal/syscall/syscall_linux.go
+
+package client
+
+import (
+	"fmt"
+	"net"
+	"syscall"
+	"time"
+
+	"golang.org/x/sys/unix"
+)
+
+// setTCPUserTimeout sets the TCP user timeout on a connection's socket
+func setTCPUserTimeout(conn net.Conn, timeout time.Duration) error {
+	tcpconn, ok := conn.(*net.TCPConn)
+	if !ok {
+		// not a TCP connection. exit early
+		return nil
+	}
+	rawConn, err := tcpconn.SyscallConn()
+	if err != nil {
+		return fmt.Errorf("error getting raw connection: %v", err)
+	}
+	err = rawConn.Control(func(fd uintptr) {
+		err = syscall.SetsockoptInt(int(fd), syscall.IPPROTO_TCP, unix.TCP_USER_TIMEOUT, int(timeout/time.Millisecond))
+	})
+	if err != nil {
+		return fmt.Errorf("error setting option on socket: %v", err)
+	}
+
+	return nil
+}

client/syscall_nonlinux.go

@@ -0,0 +1,14 @@
+//go:build !linux
+// +build !linux
+
+package client
+
+import (
+	"net"
+	"time"
+)
+
+// setTCPUserTimeout is a no-op function under non-linux environments
+func setTCPUserTimeout(conn net.Conn, timeout time.Duration) error {
+	return nil
+}

go.mod

@@ -13,6 +13,7 @@ require (
 	github.com/ovn-kubernetes/libovsdb v0.8.1
 	github.com/prometheus/client_golang v1.23.2
 	github.com/stretchr/testify v1.11.1
+	golang.org/x/sys v0.39.0
 	golang.org/x/text v0.32.0
 )
 
@@ -55,7 +56,6 @@ require (
 	github.com/xeipuuv/gojsonschema v1.2.0 // indirect
 	go.yaml.in/yaml/v2 v2.4.3 // indirect
 	golang.org/x/crypto v0.46.0 // indirect
-	golang.org/x/sys v0.39.0 // indirect
 	google.golang.org/protobuf v1.36.10 // indirect
 	gopkg.in/yaml.v2 v2.4.0 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect