fix: limit observed addresses in address manager

This is done in the identify protocol but the address manager
should guard itself against misuse.

packages/libp2p/src/address-manager.ts

@@ -32,6 +32,11 @@ export interface AddressManagerInit {
    * A list of string multiaddrs to add to the list of announced addresses
    */
   appendAnnounce?: string[]
+
+  /**
+   * Limits the number of observed addresses we will store
+   */
+  maxObservedAddresses?: number
 }
 
 export interface AddressManagerComponents {
@@ -103,6 +108,7 @@ export class AddressManager implements AddressManagerInterface {
   private readonly announceFilter: AddressFilter
   private readonly ipDomainMappings: Map<string, DNSMapping>
   private readonly publicAddressMappings: Map<string, PublicAddressMapping[]>
+  private readonly maxObservedAddresses: number
 
   /**
    * Responsible for managing the peer addresses.
@@ -122,6 +128,7 @@ export class AddressManager implements AddressManagerInterface {
     this.ipDomainMappings = new Map()
     this.publicAddressMappings = new Map()
     this.announceFilter = init.announceFilter ?? defaultAddressFilter
+    this.maxObservedAddresses = init.maxObservedAddresses ?? 10
 
     // this method gets called repeatedly on startup when transports start listening so
     // debounce it so we don't cause multiple self:peer:update events to be emitted
@@ -192,6 +199,10 @@ export class AddressManager implements AddressManagerInterface {
    * Add peer observed addresses
    */
   addObservedAddr (addr: Multiaddr): void {
+    if (this.observed.size === this.maxObservedAddresses) {
+      return
+    }
+
     addr = stripPeerId(addr, this.components.peerId)
     const addrString = addr.toString()
 

packages/libp2p/src/config.ts

@@ -10,7 +10,8 @@ const DefaultConfig: Libp2pInit = {
     listen: [],
     announce: [],
     noAnnounce: [],
-    announceFilter: (multiaddrs: Multiaddr[]) => multiaddrs
+    announceFilter: (multiaddrs: Multiaddr[]) => multiaddrs,
+    maxObservedAddresses: 10
   },
   connectionManager: {
     resolvers: {

packages/libp2p/test/addresses/address-manager.spec.ts

@@ -130,6 +130,26 @@ describe('Address Manager', () => {
     expect(am.getObservedAddrs()).to.have.lengthOf(1)
   })
 
+  it('should limit observed addresses', () => {
+    const am = new AddressManager({
+      peerId,
+      transportManager: stubInterface<TransportManager>(),
+      peerStore,
+      events,
+      logger: defaultLogger()
+    }, {
+      announceFilter: stubInterface<AddressFilter>()
+    })
+
+    expect(am.getObservedAddrs()).to.be.empty()
+
+    for (let i = 0; i < 100; i++) {
+      am.addObservedAddr(multiaddr(`/ip4/123.123.123.123/tcp/392${i}`))
+    }
+
+    expect(am.getObservedAddrs()).to.have.lengthOf(10)
+  })
+
   it('should allow duplicate listen addresses', () => {
     const ma = multiaddr('/ip4/0.0.0.0/tcp/0')
     const am = new AddressManager({