feat: allow overriding stream handlers

Adds a `force` flag to `libp2p.handle` that means the method will
not throw if a handler already exists for the protocol being handled.

Fixes #2928

packages/interface-internal/src/registrar/index.ts

@@ -1,56 +1,25 @@
-import type { Connection, Stream, Topology } from '@libp2p/interface'
+import type { StreamHandler, StreamHandlerOptions, StreamHandlerRecord, Topology, IncomingStreamData } from '@libp2p/interface'
 
-export interface IncomingStreamData {
+export type {
   /**
-   * The stream that has been opened
+   * @deprecated This type should be imported from @libp2p/interface directly
    */
-  stream: Stream
+  IncomingStreamData,
 
   /**
-   * The connection that the stream was opened on
+   * @deprecated This type should be imported from @libp2p/interface directly
    */
-  connection: Connection
-}
-
-export interface StreamHandler {
-  (data: IncomingStreamData): void
-}
-
-export interface StreamHandlerOptions {
-  /**
-   * How many incoming streams can be open for this protocol at the same time on each connection
-   *
-   * @default 32
-   */
-  maxInboundStreams?: number
-
-  /**
-   * How many outgoing streams can be open for this protocol at the same time on each connection
-   *
-   * @default 64
-   */
-  maxOutboundStreams?: number
-
-  /**
-   * If true, allow this protocol to run on limited connections (e.g.
-   * connections with data or duration limits such as circuit relay
-   * connections)
-   *
-   * @default false
-   */
-  runOnLimitedConnection?: boolean
-}
+  StreamHandler,
 
-export interface StreamHandlerRecord {
   /**
-   * The handler that was registered to handle streams opened on the protocol
+   * @deprecated This type should be imported from @libp2p/interface directly
    */
-  handler: StreamHandler
+  StreamHandlerOptions,
 
   /**
-   * The options that were used to register the stream handler
+   * @deprecated This type should be imported from @libp2p/interface directly
    */
-  options: StreamHandlerOptions
+  StreamHandlerRecord
 }
 
 export interface Registrar {

packages/interface/src/index.ts

@@ -620,7 +620,8 @@ export interface Libp2p<T extends ServiceMap = ServiceMap> extends Startable, Ty
    *
    * `libp2p.handle(protocols, handler, options)`
    *
-   * In the event of a new handler for the same protocol being added, the first one is discarded.
+   * In the event of a new handler for the same protocol being added and error
+   * will be thrown. Pass `force: true` to override this.
    *
    * @example
    *

packages/interface/src/stream-handler/index.ts

@@ -1,11 +1,21 @@
 import type { Connection, Stream } from '../connection/index.js'
 
 export interface IncomingStreamData {
+  /**
+   * The newly opened stream
+   */
   stream: Stream
+
+  /**
+   * The connection the stream was opened on
+   */
   connection: Connection
 }
 
 export interface StreamHandler {
+  /**
+   * A callback function that accepts the incoming stream data
+   */
   (data: IncomingStreamData): void
 }
 
@@ -29,9 +39,22 @@ export interface StreamHandlerOptions {
    * transferred or how long it can be open for.
    */
   runOnLimitedConnection?: boolean
+
+  /**
+   * If `true`, and a handler is already registered for the specified
+   * protocol(s), the existing handler will be discarded.
+   */
+  force?: true
 }
 
 export interface StreamHandlerRecord {
+  /**
+   * The handler that was registered to handle streams opened on the protocol
+   */
   handler: StreamHandler
+
+  /**
+   * The options that were used to register the stream handler
+   */
   options: StreamHandlerOptions
 }

packages/libp2p/src/libp2p.ts

@@ -16,15 +16,14 @@ import { ConnectionMonitor } from './connection-monitor.js'
 import { CompoundContentRouting } from './content-routing.js'
 import { DefaultPeerRouting } from './peer-routing.js'
 import { RandomWalk } from './random-walk.js'
-import { DefaultRegistrar } from './registrar.js'
+import { Registrar } from './registrar.js'
 import { DefaultTransportManager } from './transport-manager.js'
 import { DefaultUpgrader } from './upgrader.js'
 import { userAgent } from './user-agent.js'
 import * as pkg from './version.js'
 import type { Components } from './components.js'
 import type { Libp2p as Libp2pInterface, Libp2pInit } from './index.js'
-import type { PeerRouting, ContentRouting, Libp2pEvents, PendingDial, ServiceMap, AbortOptions, ComponentLogger, Logger, Connection, NewStreamOptions, Stream, Metrics, PeerId, PeerInfo, PeerStore, Topology, Libp2pStatus, IsDialableOptions, DialOptions, PublicKey, Ed25519PeerId, Secp256k1PeerId, RSAPublicKey, RSAPeerId, URLPeerId, Ed25519PublicKey, Secp256k1PublicKey } from '@libp2p/interface'
-import type { StreamHandler, StreamHandlerOptions } from '@libp2p/interface-internal'
+import type { PeerRouting, ContentRouting, Libp2pEvents, PendingDial, ServiceMap, AbortOptions, ComponentLogger, Logger, Connection, NewStreamOptions, Stream, Metrics, PeerId, PeerInfo, PeerStore, Topology, Libp2pStatus, IsDialableOptions, DialOptions, PublicKey, Ed25519PeerId, Secp256k1PeerId, RSAPublicKey, RSAPeerId, URLPeerId, Ed25519PublicKey, Secp256k1PublicKey, StreamHandler, StreamHandlerOptions } from '@libp2p/interface'
 
 export class Libp2p<T extends ServiceMap = ServiceMap> extends TypedEventEmitter<Libp2pEvents> implements Libp2pInterface<T> {
   public peerId: PeerId
@@ -132,7 +131,7 @@ export class Libp2p<T extends ServiceMap = ServiceMap> extends TypedEventEmitter
     }
 
     // Create the Registrar
-    this.configureComponent('registrar', new DefaultRegistrar(this.components))
+    this.configureComponent('registrar', new Registrar(this.components))
 
     // Addresses {listen, announce, noAnnounce}
     this.configureComponent('addressManager', new AddressManager(this.components, init.addresses))

packages/libp2p/src/registrar.ts

@@ -1,8 +1,8 @@
 import { InvalidParametersError } from '@libp2p/interface'
 import merge from 'merge-options'
 import * as errorsJs from './errors.js'
-import type { IdentifyResult, Libp2pEvents, Logger, PeerUpdate, TypedEventTarget, PeerId, PeerStore, Topology } from '@libp2p/interface'
-import type { StreamHandlerOptions, StreamHandlerRecord, Registrar, StreamHandler } from '@libp2p/interface-internal'
+import type { IdentifyResult, Libp2pEvents, Logger, PeerUpdate, TypedEventTarget, PeerId, PeerStore, Topology, StreamHandlerRecord, StreamHandlerOptions } from '@libp2p/interface'
+import type { Registrar as RegistrarInterface, StreamHandler } from '@libp2p/interface-internal'
 import type { ComponentLogger } from '@libp2p/logger'
 
 export const DEFAULT_MAX_INBOUND_STREAMS = 32
@@ -18,7 +18,7 @@ export interface RegistrarComponents {
 /**
  * Responsible for notifying registered protocols of events in the network.
  */
-export class DefaultRegistrar implements Registrar {
+export class Registrar implements RegistrarInterface {
   private readonly log: Logger
   private readonly topologies: Map<string, Map<string, Topology>>
   private readonly handlers: Map<string, StreamHandlerRecord>
@@ -73,7 +73,7 @@ export class DefaultRegistrar implements Registrar {
    * Registers the `handler` for each protocol
    */
   async handle (protocol: string, handler: StreamHandler, opts?: StreamHandlerOptions): Promise<void> {
-    if (this.handlers.has(protocol)) {
+    if (this.handlers.has(protocol) && opts?.force !== true) {
       throw new errorsJs.DuplicateProtocolHandlerError(`Handler already registered for protocol ${protocol}`)
     }
 

packages/libp2p/test/registrar/errors.spec.ts

@@ -9,10 +9,10 @@ import { MemoryDatastore } from 'datastore-core/memory'
 import { stubInterface } from 'sinon-ts'
 import { defaultComponents } from '../../src/components.js'
 import { DefaultConnectionManager } from '../../src/connection-manager/index.js'
-import { DefaultRegistrar } from '../../src/registrar.js'
+import { Registrar } from '../../src/registrar.js'
 import type { Components } from '../../src/components.js'
 import type { Upgrader, ConnectionGater, PeerId } from '@libp2p/interface'
-import type { Registrar, TransportManager } from '@libp2p/interface-internal'
+import type { TransportManager } from '@libp2p/interface-internal'
 
 describe('registrar errors', () => {
   let components: Components
@@ -35,7 +35,7 @@ describe('registrar errors', () => {
       maxConnections: 1000,
       inboundUpgradeTimeout: 1000
     })
-    registrar = new DefaultRegistrar(components)
+    registrar = new Registrar(components)
   })
 
   it('should fail to register a protocol if no multicodec is provided', () => {

packages/libp2p/test/registrar/protocols.spec.ts

@@ -5,15 +5,13 @@ import pDefer from 'p-defer'
 import { createLibp2p } from '../../src/index.js'
 import type { Components } from '../../src/components.js'
 import type { Libp2p } from '@libp2p/interface'
+import type { Registrar } from '@libp2p/interface-internal'
 
 describe('registrar protocols', () => {
   let libp2p: Libp2p
+  let registrar: Registrar
 
-  afterEach(async () => {
-    await libp2p?.stop()
-  })
-
-  it('should be able to register and unregister a handler', async () => {
+  beforeEach(async () => {
     const deferred = pDefer<Components>()
 
     libp2p = await createLibp2p({
@@ -25,9 +23,14 @@ describe('registrar protocols', () => {
     })
 
     const components = await deferred.promise
+    registrar = components.registrar
+  })
 
-    const registrar = components.registrar
+  afterEach(async () => {
+    await libp2p?.stop()
+  })
 
+  it('should be able to register and unregister a handler', async () => {
     expect(registrar.getProtocols()).to.not.have.any.keys(['/echo/1.0.0', '/echo/1.0.1'])
 
     const echoHandler = (): void => {}
@@ -43,4 +46,38 @@ describe('registrar protocols', () => {
       '/echo/1.0.1'
     ])
   })
+
+  it('should error if registering two handlers for the same protocol', async () => {
+    const echoHandler = (): void => {}
+    await libp2p.handle('/echo/1.0.0', echoHandler)
+
+    await expect(libp2p.handle('/echo/1.0.0', echoHandler)).to.eventually.be.rejected
+      .with.property('name', 'DuplicateProtocolHandlerError')
+  })
+
+  it('should error if registering two handlers for the same protocols', async () => {
+    const echoHandler = (): void => {}
+    await libp2p.handle('/echo/1.0.0', echoHandler)
+
+    await expect(libp2p.handle(['/echo/2.0.0', '/echo/1.0.0'], echoHandler)).to.eventually.be.rejected
+      .with.property('name', 'DuplicateProtocolHandlerError')
+  })
+
+  it('should not error if force-registering two handlers for the same protocol', async () => {
+    const echoHandler = (): void => {}
+    await libp2p.handle('/echo/1.0.0', echoHandler)
+
+    await expect(libp2p.handle('/echo/1.0.0', echoHandler, {
+      force: true
+    })).to.eventually.be.ok
+  })
+
+  it('should not error if force-registering two handlers for the same protocols', async () => {
+    const echoHandler = (): void => {}
+    await libp2p.handle('/echo/1.0.0', echoHandler)
+
+    await expect(libp2p.handle(['/echo/2.0.0', '/echo/1.0.0'], echoHandler, {
+      force: true
+    })).to.eventually.be.ok
+  })
 })

packages/libp2p/test/registrar/registrar.spec.ts

@@ -8,9 +8,8 @@ import { peerIdFromPrivateKey } from '@libp2p/peer-id'
 import { expect } from 'aegir/chai'
 import pDefer from 'p-defer'
 import { stubInterface } from 'sinon-ts'
-import { DefaultRegistrar } from '../../src/registrar.js'
+import { Registrar } from '../../src/registrar.js'
 import type { TypedEventTarget, Libp2pEvents, PeerId, PeerStore, Topology, Peer, Connection } from '@libp2p/interface'
-import type { Registrar } from '@libp2p/interface-internal'
 import type { StubbedInstance } from 'sinon-ts'
 
 const protocol = '/test/1.0.0'
@@ -31,7 +30,7 @@ describe('registrar topologies', () => {
     peerStore = stubInterface<PeerStore>()
     events = new TypedEventEmitter<Libp2pEvents>()
 
-    registrar = new DefaultRegistrar({
+    registrar = new Registrar({
       peerId,
       peerStore,
       events,