// Copyright (c) Tailscale Inc & AUTHORS // SPDX-License-Identifier: BSD-3-Clause package netmap import ( "cmp" "fmt" "net/netip" "reflect" "slices" "sync" "time" "tailscale.com/tailcfg" "tailscale.com/types/ptr" ) // NodeMutation is the common interface for types that describe // the change of a node's state. type NodeMutation interface { NodeIDBeingMutated() tailcfg.NodeID Apply(*tailcfg.Node) } type mutatingNodeID tailcfg.NodeID func (m mutatingNodeID) NodeIDBeingMutated() tailcfg.NodeID { return tailcfg.NodeID(m) } // NodeMutationDERPHome is a NodeMutation that says a node // has changed its DERP home region. type NodeMutationDERPHome struct { mutatingNodeID DERPRegion int } func (m NodeMutationDERPHome) Apply(n *tailcfg.Node) { n.DERP = fmt.Sprintf("127.3.3.40:%v", m.DERPRegion) } // NodeMutation is a NodeMutation that says a node's endpoints have changed. type NodeMutationEndpoints struct { mutatingNodeID Endpoints []netip.AddrPort } func (m NodeMutationEndpoints) Apply(n *tailcfg.Node) { n.Endpoints = slices.Clone(m.Endpoints) } // NodeMutationOnline is a NodeMutation that says a node is now online or // offline. type NodeMutationOnline struct { mutatingNodeID Online bool } func (m NodeMutationOnline) Apply(n *tailcfg.Node) { n.Online = ptr.To(m.Online) } // NodeMutationLastSeen is a NodeMutation that says a node's LastSeen // value should be set to the current time. type NodeMutationLastSeen struct { mutatingNodeID LastSeen time.Time } func (m NodeMutationLastSeen) Apply(n *tailcfg.Node) { n.LastSeen = ptr.To(m.LastSeen) } var peerChangeFields = sync.OnceValue(func() []reflect.StructField { var fields []reflect.StructField rt := reflect.TypeOf((*tailcfg.PeerChange)(nil)).Elem() for i := 0; i < rt.NumField(); i++ { fields = append(fields, rt.Field(i)) } return fields }) // NodeMutationsFromPatch returns the NodeMutations that // p describes. If p describes something not yet supported // by a specific NodeMutation type, it returns (nil, false). func NodeMutationsFromPatch(p *tailcfg.PeerChange) (_ []NodeMutation, ok bool) { if p == nil || p.NodeID == 0 { return nil, false } var ret []NodeMutation rv := reflect.ValueOf(p).Elem() for i, sf := range peerChangeFields() { if rv.Field(i).IsZero() { continue } switch sf.Name { default: // Unhandled field. return nil, false case "NodeID": continue case "DERPRegion": ret = append(ret, NodeMutationDERPHome{mutatingNodeID(p.NodeID), p.DERPRegion}) case "Endpoints": ret = append(ret, NodeMutationEndpoints{mutatingNodeID(p.NodeID), slices.Clone(p.Endpoints)}) case "Online": ret = append(ret, NodeMutationOnline{mutatingNodeID(p.NodeID), *p.Online}) case "LastSeen": ret = append(ret, NodeMutationLastSeen{mutatingNodeID(p.NodeID), *p.LastSeen}) } } return ret, true } // MutationsFromMapResponse returns all the discrete node mutations described // by res. It returns ok=false if res contains any non-patch field as defined // by mapResponseContainsNonPatchFields. func MutationsFromMapResponse(res *tailcfg.MapResponse, now time.Time) (ret []NodeMutation, ok bool) { if now.IsZero() { now = time.Now() } if mapResponseContainsNonPatchFields(res) { return nil, false } // All that remains is PeersChangedPatch, OnlineChange, and LastSeenChange. for _, p := range res.PeersChangedPatch { deltas, ok := NodeMutationsFromPatch(p) if !ok { return nil, false } ret = append(ret, deltas...) } for nid, v := range res.OnlineChange { ret = append(ret, NodeMutationOnline{mutatingNodeID(nid), v}) } for nid, v := range res.PeerSeenChange { if v { ret = append(ret, NodeMutationLastSeen{mutatingNodeID(nid), now}) } } slices.SortStableFunc(ret, func(a, b NodeMutation) int { return cmp.Compare(a.NodeIDBeingMutated(), b.NodeIDBeingMutated()) }) return ret, true } // mapResponseContainsNonPatchFields reports whether res contains only "patch" // fields set (PeersChangedPatch primarily, but also including the legacy // PeerSeenChange and OnlineChange fields). // // It ignores any of the meta fields that are handled by PollNetMap before the // peer change handling gets involved. // // The purpose of this function is to ask whether this is a tricky enough // MapResponse to warrant a full netmap update. When this returns false, it // means the response can be handled incrementally, patching up the local state. func mapResponseContainsNonPatchFields(res *tailcfg.MapResponse) bool { return res.Node != nil || res.DERPMap != nil || res.DNSConfig != nil || res.Domain != "" || res.CollectServices != "" || res.PacketFilter != nil || res.PacketFilters != nil || res.UserProfiles != nil || res.Health != nil || res.SSHPolicy != nil || res.TKAInfo != nil || res.DomainDataPlaneAuditLogID != "" || res.Debug != nil || res.ControlDialPlan != nil || res.ClientVersion != nil || res.Peers != nil || res.PeersRemoved != nil || // PeersChanged is too coarse to be considered a patch. Also, we convert // PeersChanged to PeersChangedPatch in patchifyPeersChanged before this // function is called, so it should never be set anyway. But for // completedness, and for tests, check it too: res.PeersChanged != nil || res.DefaultAutoUpdate != "" || res.MaxKeyDuration > 0 }