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| 1 | +package msgmux |
| 2 | + |
| 3 | +// For some reason golangci-lint has a false positive on the sort order of the |
| 4 | +// imports for the new "maps" package... We need the nolint directive here to |
| 5 | +// ignore that. |
| 6 | +// |
| 7 | +//nolint:gci |
| 8 | +import ( |
| 9 | + "fmt" |
| 10 | + "maps" |
| 11 | + "sync" |
| 12 | + |
| 13 | + "github.com/btcsuite/btcd/btcec/v2" |
| 14 | + "github.com/lightningnetwork/lnd/fn" |
| 15 | + "github.com/lightningnetwork/lnd/lnwire" |
| 16 | +) |
| 17 | + |
| 18 | +var ( |
| 19 | + // ErrDuplicateEndpoint is returned when an endpoint is registered with |
| 20 | + // a name that already exists. |
| 21 | + ErrDuplicateEndpoint = fmt.Errorf("endpoint already registered") |
| 22 | + |
| 23 | + // ErrUnableToRouteMsg is returned when a message is unable to be |
| 24 | + // routed to any endpoints. |
| 25 | + ErrUnableToRouteMsg = fmt.Errorf("unable to route message") |
| 26 | +) |
| 27 | + |
| 28 | +// EndpointName is the name of a given endpoint. This MUST be unique across all |
| 29 | +// registered endpoints. |
| 30 | +type EndpointName = string |
| 31 | + |
| 32 | +// PeerMsg is a wire message that includes the public key of the peer that sent |
| 33 | +// it. |
| 34 | +type PeerMsg struct { |
| 35 | + lnwire.Message |
| 36 | + |
| 37 | + // PeerPub is the public key of the peer that sent this message. |
| 38 | + PeerPub btcec.PublicKey |
| 39 | +} |
| 40 | + |
| 41 | +// Endpoint is an interface that represents a message endpoint, or the |
| 42 | +// sub-system that will handle processing an incoming wire message. |
| 43 | +type Endpoint interface { |
| 44 | + // Name returns the name of this endpoint. This MUST be unique across |
| 45 | + // all registered endpoints. |
| 46 | + Name() EndpointName |
| 47 | + |
| 48 | + // CanHandle returns true if the target message can be routed to this |
| 49 | + // endpoint. |
| 50 | + CanHandle(msg PeerMsg) bool |
| 51 | + |
| 52 | + // SendMessage handles the target message, and returns true if the |
| 53 | + // message was able being processed. |
| 54 | + SendMessage(msg PeerMsg) bool |
| 55 | +} |
| 56 | + |
| 57 | +// MsgRouter is an interface that represents a message router, which is generic |
| 58 | +// sub-system capable of routing any incoming wire message to a set of |
| 59 | +// registered endpoints. |
| 60 | +type Router interface { |
| 61 | + // RegisterEndpoint registers a new endpoint with the router. If a |
| 62 | + // duplicate endpoint exists, an error is returned. |
| 63 | + RegisterEndpoint(Endpoint) error |
| 64 | + |
| 65 | + // UnregisterEndpoint unregisters the target endpoint from the router. |
| 66 | + UnregisterEndpoint(EndpointName) error |
| 67 | + |
| 68 | + // RouteMsg attempts to route the target message to a registered |
| 69 | + // endpoint. If ANY endpoint could handle the message, then nil is |
| 70 | + // returned. Otherwise, ErrUnableToRouteMsg is returned. |
| 71 | + RouteMsg(PeerMsg) error |
| 72 | + |
| 73 | + // Start starts the peer message router. |
| 74 | + Start() |
| 75 | + |
| 76 | + // Stop stops the peer message router. |
| 77 | + Stop() |
| 78 | +} |
| 79 | + |
| 80 | +// sendQuery sends a query to the main event loop, and returns the response. |
| 81 | +func sendQuery[Q any, R any](sendChan chan fn.Req[Q, R], queryArg Q, |
| 82 | + quit chan struct{}) fn.Result[R] { |
| 83 | + |
| 84 | + query, respChan := fn.NewReq[Q, R](queryArg) |
| 85 | + |
| 86 | + if !fn.SendOrQuit(sendChan, query, quit) { |
| 87 | + return fn.Errf[R]("router shutting down") |
| 88 | + } |
| 89 | + |
| 90 | + return fn.NewResult(fn.RecvResp(respChan, nil, quit)) |
| 91 | +} |
| 92 | + |
| 93 | +// sendQueryErr is a helper function based on sendQuery that can be used when |
| 94 | +// the query only needs an error response. |
| 95 | +func sendQueryErr[Q any](sendChan chan fn.Req[Q, error], queryArg Q, |
| 96 | + quitChan chan struct{}) error { |
| 97 | + |
| 98 | + return fn.ElimEither( |
| 99 | + fn.Iden, fn.Iden, |
| 100 | + sendQuery(sendChan, queryArg, quitChan).Either, |
| 101 | + ) |
| 102 | +} |
| 103 | + |
| 104 | +// EndpointsMap is a map of all registered endpoints. |
| 105 | +type EndpointsMap map[EndpointName]Endpoint |
| 106 | + |
| 107 | +// MultiMsgRouter is a type of message router that is capable of routing new |
| 108 | +// incoming messages, permitting a message to be routed to multiple registered |
| 109 | +// endpoints. |
| 110 | +type MultiMsgRouter struct { |
| 111 | + startOnce sync.Once |
| 112 | + stopOnce sync.Once |
| 113 | + |
| 114 | + // registerChan is the channel that all new endpoints will be sent to. |
| 115 | + registerChan chan fn.Req[Endpoint, error] |
| 116 | + |
| 117 | + // unregisterChan is the channel that all endpoints that are to be |
| 118 | + // removed are sent to. |
| 119 | + unregisterChan chan fn.Req[EndpointName, error] |
| 120 | + |
| 121 | + // msgChan is the channel that all messages will be sent to for |
| 122 | + // processing. |
| 123 | + msgChan chan fn.Req[PeerMsg, error] |
| 124 | + |
| 125 | + // endpointsQueries is a channel that all queries to the endpoints map |
| 126 | + // will be sent to. |
| 127 | + endpointQueries chan fn.Req[Endpoint, EndpointsMap] |
| 128 | + |
| 129 | + wg sync.WaitGroup |
| 130 | + quit chan struct{} |
| 131 | +} |
| 132 | + |
| 133 | +// NewMultiMsgRouter creates a new instance of a peer message router. |
| 134 | +func NewMultiMsgRouter() *MultiMsgRouter { |
| 135 | + return &MultiMsgRouter{ |
| 136 | + registerChan: make(chan fn.Req[Endpoint, error]), |
| 137 | + unregisterChan: make(chan fn.Req[EndpointName, error]), |
| 138 | + msgChan: make(chan fn.Req[PeerMsg, error]), |
| 139 | + endpointQueries: make(chan fn.Req[Endpoint, EndpointsMap]), |
| 140 | + quit: make(chan struct{}), |
| 141 | + } |
| 142 | +} |
| 143 | + |
| 144 | +// Start starts the peer message router. |
| 145 | +func (p *MultiMsgRouter) Start() { |
| 146 | + log.Infof("Starting Router") |
| 147 | + |
| 148 | + p.startOnce.Do(func() { |
| 149 | + p.wg.Add(1) |
| 150 | + go p.msgRouter() |
| 151 | + }) |
| 152 | +} |
| 153 | + |
| 154 | +// Stop stops the peer message router. |
| 155 | +func (p *MultiMsgRouter) Stop() { |
| 156 | + log.Infof("Stopping Router") |
| 157 | + |
| 158 | + p.stopOnce.Do(func() { |
| 159 | + close(p.quit) |
| 160 | + p.wg.Wait() |
| 161 | + }) |
| 162 | +} |
| 163 | + |
| 164 | +// RegisterEndpoint registers a new endpoint with the router. If a duplicate |
| 165 | +// endpoint exists, an error is returned. |
| 166 | +func (p *MultiMsgRouter) RegisterEndpoint(endpoint Endpoint) error { |
| 167 | + return sendQueryErr(p.registerChan, endpoint, p.quit) |
| 168 | +} |
| 169 | + |
| 170 | +// UnregisterEndpoint unregisters the target endpoint from the router. |
| 171 | +func (p *MultiMsgRouter) UnregisterEndpoint(name EndpointName) error { |
| 172 | + return sendQueryErr(p.unregisterChan, name, p.quit) |
| 173 | +} |
| 174 | + |
| 175 | +// RouteMsg attempts to route the target message to a registered endpoint. If |
| 176 | +// ANY endpoint could handle the message, then nil is returned. |
| 177 | +func (p *MultiMsgRouter) RouteMsg(msg PeerMsg) error { |
| 178 | + return sendQueryErr(p.msgChan, msg, p.quit) |
| 179 | +} |
| 180 | + |
| 181 | +// Endpoints returns a list of all registered endpoints. |
| 182 | +func (p *MultiMsgRouter) endpoints() fn.Result[EndpointsMap] { |
| 183 | + return sendQuery(p.endpointQueries, nil, p.quit) |
| 184 | +} |
| 185 | + |
| 186 | +// msgRouter is the main goroutine that handles all incoming messages. |
| 187 | +func (p *MultiMsgRouter) msgRouter() { |
| 188 | + defer p.wg.Done() |
| 189 | + |
| 190 | + // endpoints is a map of all registered endpoints. |
| 191 | + endpoints := make(map[EndpointName]Endpoint) |
| 192 | + |
| 193 | + for { |
| 194 | + select { |
| 195 | + // A new endpoint was just sent in, so we'll add it to our set |
| 196 | + // of registered endpoints. |
| 197 | + case newEndpointMsg := <-p.registerChan: |
| 198 | + endpoint := newEndpointMsg.Request |
| 199 | + |
| 200 | + log.Infof("MsgRouter: registering new "+ |
| 201 | + "Endpoint(%s)", endpoint.Name()) |
| 202 | + |
| 203 | + // If this endpoint already exists, then we'll return |
| 204 | + // an error as we require unique names. |
| 205 | + if _, ok := endpoints[endpoint.Name()]; ok { |
| 206 | + log.Errorf("MsgRouter: rejecting "+ |
| 207 | + "duplicate endpoint: %v", |
| 208 | + endpoint.Name()) |
| 209 | + |
| 210 | + newEndpointMsg.Resolve(ErrDuplicateEndpoint) |
| 211 | + |
| 212 | + continue |
| 213 | + } |
| 214 | + |
| 215 | + endpoints[endpoint.Name()] = endpoint |
| 216 | + |
| 217 | + newEndpointMsg.Resolve(nil) |
| 218 | + |
| 219 | + // A request to unregister an endpoint was just sent in, so |
| 220 | + // we'll attempt to remove it. |
| 221 | + case endpointName := <-p.unregisterChan: |
| 222 | + delete(endpoints, endpointName.Request) |
| 223 | + |
| 224 | + log.Infof("MsgRouter: unregistering "+ |
| 225 | + "Endpoint(%s)", endpointName.Request) |
| 226 | + |
| 227 | + endpointName.Resolve(nil) |
| 228 | + |
| 229 | + // A new message was just sent in. We'll attempt to route it to |
| 230 | + // all the endpoints that can handle it. |
| 231 | + case msgQuery := <-p.msgChan: |
| 232 | + msg := msgQuery.Request |
| 233 | + |
| 234 | + // Loop through all the endpoints and send the message |
| 235 | + // to those that can handle it the message. |
| 236 | + var couldSend bool |
| 237 | + for _, endpoint := range endpoints { |
| 238 | + if endpoint.CanHandle(msg) { |
| 239 | + log.Tracef("MsgRouter: sending "+ |
| 240 | + "msg %T to endpoint %s", msg, |
| 241 | + endpoint.Name()) |
| 242 | + |
| 243 | + sent := endpoint.SendMessage(msg) |
| 244 | + couldSend = couldSend || sent |
| 245 | + } |
| 246 | + } |
| 247 | + |
| 248 | + var err error |
| 249 | + if !couldSend { |
| 250 | + log.Tracef("MsgRouter: unable to route "+ |
| 251 | + "msg %T", msg) |
| 252 | + |
| 253 | + err = ErrUnableToRouteMsg |
| 254 | + } |
| 255 | + |
| 256 | + msgQuery.Resolve(err) |
| 257 | + |
| 258 | + // A query for the endpoint state just came in, we'll send back |
| 259 | + // a copy of our current state. |
| 260 | + case endpointQuery := <-p.endpointQueries: |
| 261 | + endpointsCopy := make(EndpointsMap, len(endpoints)) |
| 262 | + maps.Copy(endpointsCopy, endpoints) |
| 263 | + |
| 264 | + endpointQuery.Resolve(endpointsCopy) |
| 265 | + |
| 266 | + case <-p.quit: |
| 267 | + return |
| 268 | + } |
| 269 | + } |
| 270 | +} |
| 271 | + |
| 272 | +// A compile time check to ensure MultiMsgRouter implements the MsgRouter |
| 273 | +// interface. |
| 274 | +var _ Router = (*MultiMsgRouter)(nil) |
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