Set SO_REUSEADDR on UDP socket for scan

cmd/jag/commands/scan.go

@@ -14,12 +14,14 @@ import (
 	"os"
 	"sort"
 	"strings"
+	"syscall"
 	"time"
 
 	"github.com/manifoldco/promptui"
 	"github.com/spf13/cobra"
 	"github.com/toitlang/jaguar/cmd/jag/directory"
 	"github.com/toitware/ubjson"
+	"golang.org/x/sys/unix"
 	"gopkg.in/yaml.v2"
 )
 
@@ -236,7 +238,20 @@ func scan(ctx context.Context, ds deviceSelect, port uint) ([]Device, error) {
 		return []Device{*dev}, nil
 	}
 
-	pc, err := net.ListenPacket("udp4", fmt.Sprintf(":%d", port))
+	listenConfig := net.ListenConfig{
+		Control: func(network, address string, c syscall.RawConn) error {
+			var opErr error
+			err := c.Control(func(fd uintptr) {
+				opErr = unix.SetsockoptInt(int(fd), unix.SOL_SOCKET, unix.SO_REUSEADDR, 1)
+			})
+			if err != nil {
+				return err
+			}
+			return opErr
+		},
+	}
+
+	pc, err := listenConfig.ListenPacket(context.Background(), "udp4", fmt.Sprintf(":%d", port))
 	if err != nil {
 		return nil, err
 	}

go.mod

@@ -44,6 +44,7 @@ require (
 	go.uber.org/multierr v1.11.0 // indirect
 	golang.org/x/exp v0.0.0-20231110203233-9a3e6036ecaa // indirect
 	golang.org/x/net v0.18.0
+	golang.org/x/sys v0.14.0 // indirect
 	golang.org/x/term v0.14.0
 	golang.org/x/tools v0.15.0 // indirect
 	google.golang.org/genproto/googleapis/rpc v0.0.0-20231120223509-83a465c0220f // indirect