Monitor network changes and restart engine on detection (#1904)

2026-10-23 22:09:09 +02:00 · 2024-05-07 18:50:34 +02:00
parent 2e0047daea
commit 920877964f
38 changed files with 1027 additions and 190 deletions
@@ -0,0 +1,215 @@
+package networkmonitor
+
+import (
+	"context"
+	"fmt"
+	"net"
+	"net/netip"
+	"time"
+
+	log "github.com/sirupsen/logrus"
+
+	"github.com/netbirdio/netbird/client/internal/routemanager"
+)
+
+const (
+	unreachable = 0
+	incomplete  = 1
+	probe       = 2
+	delay       = 3
+	stale       = 4
+	reachable   = 5
+	permanent   = 6
+	tbd         = 7
+)
+
+const interval = 10 * time.Second
+
+func checkChange(ctx context.Context, nexthopv4 netip.Addr, intfv4 *net.Interface, nexthopv6 netip.Addr, intfv6 *net.Interface, callback func()) error {
+	var neighborv4, neighborv6 *routemanager.Neighbor
+	{
+		initialNeighbors, err := getNeighbors()
+		if err != nil {
+			return fmt.Errorf("get neighbors: %w", err)
+		}
+
+		if n, ok := initialNeighbors[nexthopv4]; ok {
+			neighborv4 = &n
+		}
+		if n, ok := initialNeighbors[nexthopv6]; ok {
+			neighborv6 = &n
+		}
+	}
+	log.Debugf("Network monitor: initial IPv4 neighbor: %v, IPv6 neighbor: %v", neighborv4, neighborv6)
+
+	ticker := time.NewTicker(interval)
+	defer ticker.Stop()
+
+	for {
+		select {
+		case <-ctx.Done():
+			return ctx.Err()
+		case <-ticker.C:
+			if changed(nexthopv4, intfv4, neighborv4, nexthopv6, intfv6, neighborv6) {
+				callback()
+				return nil
+			}
+		}
+	}
+}
+
+func changed(
+	nexthopv4 netip.Addr,
+	intfv4 *net.Interface,
+	neighborv4 *routemanager.Neighbor,
+	nexthopv6 netip.Addr,
+	intfv6 *net.Interface,
+	neighborv6 *routemanager.Neighbor,
+) bool {
+	neighbors, err := getNeighbors()
+	if err != nil {
+		log.Errorf("network monitor: error fetching current neighbors: %v", err)
+		return false
+	}
+	if neighborChanged(nexthopv4, neighborv4, neighbors) || neighborChanged(nexthopv6, neighborv6, neighbors) {
+		return true
+	}
+
+	routes, err := getRoutes()
+	if err != nil {
+		log.Errorf("network monitor: error fetching current routes: %v", err)
+		return false
+	}
+
+	if routeChanged(nexthopv4, intfv4, routes) || routeChanged(nexthopv6, intfv6, routes) {
+		return true
+	}
+
+	return false
+}
+
+// routeChanged checks if the default routes still point to our nexthop/interface
+func routeChanged(nexthop netip.Addr, intf *net.Interface, routes map[netip.Prefix]routemanager.Route) bool {
+	if !nexthop.IsValid() {
+		return false
+	}
+
+	var unspec netip.Prefix
+	if nexthop.Is6() {
+		unspec = netip.PrefixFrom(netip.IPv6Unspecified(), 0)
+	} else {
+		unspec = netip.PrefixFrom(netip.IPv4Unspecified(), 0)
+	}
+
+	if r, ok := routes[unspec]; ok {
+		if r.Nexthop != nexthop || compareIntf(r.Interface, intf) != 0 {
+			intf := "<nil>"
+			if r.Interface != nil {
+				intf = r.Interface.Name
+			}
+			log.Infof("network monitor: default route changed: %s via %s (%s)", r.Destination, r.Nexthop, intf)
+			return true
+		}
+	} else {
+		log.Infof("network monitor: default route is gone")
+		return true
+	}
+
+	return false
+
+}
+
+func neighborChanged(nexthop netip.Addr, neighbor *routemanager.Neighbor, neighbors map[netip.Addr]routemanager.Neighbor) bool {
+	if neighbor == nil {
+		return false
+	}
+
+	// TODO: consider non-local nexthops, e.g. on point-to-point interfaces
+	if n, ok := neighbors[nexthop]; ok {
+		if n.State != reachable && n.State != permanent {
+			log.Infof("network monitor: neighbor %s (%s) is not reachable: %s", neighbor.IPAddress, neighbor.LinkLayerAddress, stateFromInt(n.State))
+			return true
+		} else if n.InterfaceIndex != neighbor.InterfaceIndex {
+			log.Infof(
+				"network monitor: neighbor %s (%s) changed interface from '%s' (%d) to '%s' (%d): %s",
+				neighbor.IPAddress,
+				neighbor.LinkLayerAddress,
+				neighbor.InterfaceAlias,
+				neighbor.InterfaceIndex,
+				n.InterfaceAlias,
+				n.InterfaceIndex,
+				stateFromInt(n.State),
+			)
+			return true
+		}
+	} else {
+		log.Infof("network monitor: neighbor %s (%s) is gone", neighbor.IPAddress, neighbor.LinkLayerAddress)
+		return true
+	}
+
+	return false
+}
+
+func getNeighbors() (map[netip.Addr]routemanager.Neighbor, error) {
+	entries, err := routemanager.GetNeighbors()
+	if err != nil {
+		return nil, fmt.Errorf("get neighbors: %w", err)
+	}
+
+	neighbours := make(map[netip.Addr]routemanager.Neighbor, len(entries))
+	for _, entry := range entries {
+		neighbours[entry.IPAddress] = entry
+	}
+
+	return neighbours, nil
+}
+
+func getRoutes() (map[netip.Prefix]routemanager.Route, error) {
+	entries, err := routemanager.GetRoutes()
+	if err != nil {
+		return nil, fmt.Errorf("get routes: %w", err)
+	}
+
+	routes := make(map[netip.Prefix]routemanager.Route, len(entries))
+	for _, entry := range entries {
+		routes[entry.Destination] = entry
+	}
+
+	return routes, nil
+}
+
+func stateFromInt(state uint8) string {
+	switch state {
+	case unreachable:
+		return "unreachable"
+	case incomplete:
+		return "incomplete"
+	case probe:
+		return "probe"
+	case delay:
+		return "delay"
+	case stale:
+		return "stale"
+	case reachable:
+		return "reachable"
+	case permanent:
+		return "permanent"
+	case tbd:
+		return "tbd"
+	default:
+		return "unknown"
+	}
+}
+
+func compareIntf(a, b *net.Interface) int {
+	if a == nil && b == nil {
+		return 0
+	}
+	if a == nil {
+		return -1
+	}
+	if b == nil {
+		return 1
+	}
+	return a.Index - b.Index
+}