First Commmit

experimental/libbox/neighbor_linux.go

@@ -0,0 +1,88 @@
+//go:build linux
+
+package libbox
+
+import (
+	"net"
+	"net/netip"
+	"slices"
+	"time"
+
+	"github.com/sagernet/sing-box/route"
+	E "github.com/sagernet/sing/common/exceptions"
+
+	"github.com/mdlayher/netlink"
+	"golang.org/x/sys/unix"
+)
+
+func SubscribeNeighborTable(listener NeighborUpdateListener) (*NeighborSubscription, error) {
+	entries, err := route.ReadNeighborEntries()
+	if err != nil {
+		return nil, E.Cause(err, "initial neighbor dump")
+	}
+	table := make(map[netip.Addr]net.HardwareAddr)
+	for _, entry := range entries {
+		table[entry.Address] = entry.MACAddress
+	}
+	listener.UpdateNeighborTable(tableToIterator(table))
+	connection, err := netlink.Dial(unix.NETLINK_ROUTE, &netlink.Config{
+		Groups: 1 << (unix.RTNLGRP_NEIGH - 1),
+	})
+	if err != nil {
+		return nil, E.Cause(err, "subscribe neighbor updates")
+	}
+	subscription := &NeighborSubscription{
+		done: make(chan struct{}),
+	}
+	go subscription.loop(listener, connection, table)
+	return subscription, nil
+}
+
+func (s *NeighborSubscription) loop(listener NeighborUpdateListener, connection *netlink.Conn, table map[netip.Addr]net.HardwareAddr) {
+	defer connection.Close()
+	for {
+		select {
+		case <-s.done:
+			return
+		default:
+		}
+		err := connection.SetReadDeadline(time.Now().Add(3 * time.Second))
+		if err != nil {
+			return
+		}
+		messages, err := connection.Receive()
+		if err != nil {
+			if nerr, ok := err.(net.Error); ok && nerr.Timeout() {
+				continue
+			}
+			select {
+			case <-s.done:
+				return
+			default:
+			}
+			continue
+		}
+		changed := false
+		for _, message := range messages {
+			address, mac, isDelete, ok := route.ParseNeighborMessage(message)
+			if !ok {
+				continue
+			}
+			if isDelete {
+				if _, exists := table[address]; exists {
+					delete(table, address)
+					changed = true
+				}
+			} else {
+				existing, exists := table[address]
+				if !exists || !slices.Equal(existing, mac) {
+					table[address] = mac
+					changed = true
+				}
+			}
+		}
+		if changed {
+			listener.UpdateNeighborTable(tableToIterator(table))
+		}
+	}
+}