feat(plugin-meetings): reachability- add detection of symmetric NAT

packages/@webex/plugin-meetings/src/reachability/clusterReachability.ts

@@ -6,7 +6,7 @@ import {convertStunUrlToTurn, convertStunUrlToTurnTls} from './util';
 import EventsScope from '../common/events/events-scope';
 
 import {CONNECTION_STATE, Enum, ICE_GATHERING_STATE} from '../constants';
-import {ClusterReachabilityResult} from './reachability.types';
+import {ClusterReachabilityResult, NatType} from './reachability.types';
 
 // data for the Events.resultReady event
 export type ResultEventData = {
@@ -22,9 +22,14 @@ export type ClientMediaIpsUpdatedEventData = {
   clientMediaIPs: string[];
 };
 
+export type NatTypeUpdatedEventData = {
+  natType: NatType;
+};
+
 export const Events = {
   resultReady: 'resultReady', // emitted when a cluster is reached successfully using specific protocol
   clientMediaIpsUpdated: 'clientMediaIpsUpdated', // emitted when more public IPs are found after resultReady was already sent for a given protocol
+  natTypeUpdated: 'natTypeUpdated', // emitted when NAT type is determined
 } as const;
 
 export type Events = Enum<typeof Events>;
@@ -41,6 +46,7 @@ export class ClusterReachability extends EventsScope {
   private pc?: RTCPeerConnection;
   private defer: Defer; // this defer is resolved once reachability checks for this cluster are completed
   private startTimestamp: number;
+  private srflxIceCandidates: RTCIceCandidate[] = [];
   public readonly isVideoMesh: boolean;
   public readonly name;
 
@@ -290,6 +296,44 @@ export class ClusterReachability extends EventsScope {
     }
   }
 
+  /**
+   * Determines NAT Type.
+   *
+   * @param {RTCIceCandidate} candidate
+   * @returns {void}
+   */
+  private determineNatType(candidate: RTCIceCandidate) {
+    this.srflxIceCandidates.push(candidate);
+
+    if (this.srflxIceCandidates.length > 1) {
+      const portsFound: Record<string, Set<number>> = {};
+
+      this.srflxIceCandidates.forEach((c) => {
+        const key = `${c.address}:${c.relatedPort}`;
+        if (!portsFound[key]) {
+          portsFound[key] = new Set();
+        }
+        portsFound[key].add(c.port);
+      });
+
+      Object.entries(portsFound).forEach(([, ports]) => {
+        if (ports.size > 1) {
+          // Found candidates with the same address and relatedPort, but different ports
+          this.emit(
+            {
+              file: 'clusterReachability',
+              function: 'determineNatType',
+            },
+            Events.natTypeUpdated,
+            {
+              natType: NatType.SymmetricNat,
+            }
+          );
+        }
+      });
+    }
+  }
+
   /**
    * Registers a listener for the icecandidate event
    *
@@ -308,6 +352,8 @@ export class ClusterReachability extends EventsScope {
       if (e.candidate) {
         if (e.candidate.type === CANDIDATE_TYPES.SERVER_REFLEXIVE) {
           this.saveResult('udp', latencyInMilliseconds, e.candidate.address);
+
+          this.determineNatType(e.candidate);
         }
 
         if (e.candidate.type === CANDIDATE_TYPES.RELAY) {

packages/@webex/plugin-meetings/src/reachability/index.ts

@@ -23,11 +23,13 @@ import {
   ReachabilityResultsForBackend,
   TransportResultForBackend,
   GetClustersTrigger,
+  NatType,
 } from './reachability.types';
 import {
   ClientMediaIpsUpdatedEventData,
   ClusterReachability,
   Events,
+  NatTypeUpdatedEventData,
   ResultEventData,
 } from './clusterReachability';
 import EventsScope from '../common/events/events-scope';
@@ -64,6 +66,7 @@ export default class Reachability extends EventsScope {
   resultsCount = {videoMesh: {udp: 0}, public: {udp: 0, tcp: 0, xtls: 0}};
   startTime = undefined;
   totalDuration = undefined;
+  natType = NatType.Unknown;
 
   protected lastTrigger?: string;
 
@@ -309,6 +312,7 @@ export default class Reachability extends EventsScope {
       reachability_vmn_tcp_failed: 0,
       reachability_vmn_xtls_success: 0,
       reachability_vmn_xtls_failed: 0,
+      natType: this.natType,
     };
 
     const updateStats = (clusterType: 'public' | 'vmn', result: ClusterReachabilityResult) => {
@@ -967,6 +971,13 @@ export default class Reachability extends EventsScope {
         }
       );
 
+      this.clusterReachability[key].on(
+        Events.natTypeUpdated,
+        async (data: NatTypeUpdatedEventData) => {
+          this.natType = data.natType;
+        }
+      );
+
       this.clusterReachability[key].start(); // not awaiting on purpose
     });
   }

packages/@webex/plugin-meetings/src/reachability/reachability.types.ts

@@ -7,6 +7,11 @@ export type TransportResult = {
   clientMediaIPs?: string[];
 };
 
+export enum NatType {
+  Unknown = 'unknown',
+  SymmetricNat = 'symmetric-nat',
+}
+
 // reachability result for a specific media cluster
 export type ClusterReachabilityResult = {
   udp: TransportResult;
@@ -27,6 +32,7 @@ export type ReachabilityMetrics = {
   reachability_vmn_tcp_failed: number;
   reachability_vmn_xtls_success: number;
   reachability_vmn_xtls_failed: number;
+  natType: NatType;
 };
 
 /**

packages/@webex/plugin-meetings/test/unit/spec/reachability/clusterReachability.ts

@@ -9,23 +9,27 @@ import {
   ResultEventData,
   Events,
   ClientMediaIpsUpdatedEventData,
+  NatTypeUpdatedEventData,
 } from '@webex/plugin-meetings/src/reachability/clusterReachability'; // replace with actual path
+import { NatType } from 'packages/@webex/plugin-meetings/dist/reachability/reachability.types';
 
 describe('ClusterReachability', () => {
   let previousRTCPeerConnection;
   let clusterReachability;
   let fakePeerConnection;
   let gatherIceCandidatesSpy;
 
-  const emittedEvents: Record<Events, (ResultEventData | ClientMediaIpsUpdatedEventData)[]> = {
+  const emittedEvents: Record<Events, (ResultEventData | ClientMediaIpsUpdatedEventData | NatTypeUpdatedEventData)[]> = {
     [Events.resultReady]: [],
     [Events.clientMediaIpsUpdated]: [],
+    [Events.natTypeUpdated]: [],
   };
   const FAKE_OFFER = {type: 'offer', sdp: 'fake sdp'};
 
   const resetEmittedEvents = () => {
     emittedEvents[Events.resultReady].length = 0;
     emittedEvents[Events.clientMediaIpsUpdated].length = 0;
+    emittedEvents[Events.natTypeUpdated].length = 0;
   };
   beforeEach(() => {
     fakePeerConnection = {
@@ -56,6 +60,10 @@ describe('ClusterReachability', () => {
     clusterReachability.on(Events.clientMediaIpsUpdated, (data: ClientMediaIpsUpdatedEventData) => {
       emittedEvents[Events.clientMediaIpsUpdated].push(data);
     });
+
+    clusterReachability.on(Events.natTypeUpdated, (data: NatTypeUpdatedEventData) => {
+      emittedEvents[Events.natTypeUpdated].push(data);
+    });
   });
 
   afterEach(() => {
@@ -440,5 +448,43 @@ describe('ClusterReachability', () => {
         xtls: {result: 'reachable', latencyInMilliseconds: 40},
       });
     });
+
+    it('determines correctly if symmetric-nat is detected', async () => {
+      const promise = clusterReachability.start();
+
+      // generate candidates with duplicate addresses
+      await clock.tickAsync(10);
+      fakePeerConnection.onicecandidate({candidate: {type: 'srflx', address: 'somePublicIp1', relatedPort: 3478, port: 1000}});
+
+      // check events emitted: there shouldn't be any natTypeUpdated emitted
+      assert.equal(emittedEvents[Events.natTypeUpdated].length, 0);
+
+      await clock.tickAsync(10);
+      fakePeerConnection.onicecandidate({candidate: {type: 'srflx', address: 'somePublicIp1', relatedPort: 3478, port: 2000}});
+
+      // should emit natTypeUpdated event
+      assert.equal(emittedEvents[Events.natTypeUpdated].length, 1);
+      assert.deepEqual(emittedEvents[Events.natTypeUpdated][0], {
+        natType: 'symmetric-nat',
+      });
+
+      // send also a relay candidate so that the reachability check finishes
+      fakePeerConnection.onicecandidate({candidate: {type: 'relay', address: 'someTurnRelayIp'}});
+      fakePeerConnection.onicecandidate({
+        candidate: {type: 'relay', address: 'someTurnRelayIp', port: 443},
+      });
+
+      await promise;
+
+      assert.deepEqual(clusterReachability.getResult(), {
+        udp: {
+          result: 'reachable',
+          latencyInMilliseconds: 10,
+          clientMediaIPs: ['somePublicIp1'],
+        },
+        tcp: {result: 'reachable', latencyInMilliseconds: 20},
+        xtls: {result: 'reachable', latencyInMilliseconds: 20},
+      });
+    });
   });
 });

packages/@webex/plugin-meetings/test/unit/spec/reachability/index.ts

@@ -2156,6 +2156,7 @@ describe('getReachabilityMetrics', () => {
       reachability_vmn_tcp_failed: 0,
       reachability_vmn_xtls_success: 0,
       reachability_vmn_xtls_failed: 0,
+      natType: 'unknown'
     });
   });
 
@@ -2223,6 +2224,7 @@ describe('getReachabilityMetrics', () => {
         reachability_vmn_tcp_failed: 1,
         reachability_vmn_xtls_success: 0,
         reachability_vmn_xtls_failed: 0,
+        natType: 'unknown'
       }
     );
   });
@@ -2284,6 +2286,7 @@ describe('getReachabilityMetrics', () => {
         reachability_vmn_tcp_failed: 0,
         reachability_vmn_xtls_success: 0,
         reachability_vmn_xtls_failed: 0,
+        natType: 'unknown'
       }
     );
   });
@@ -2345,6 +2348,7 @@ describe('getReachabilityMetrics', () => {
         reachability_vmn_tcp_failed: 3,
         reachability_vmn_xtls_success: 1,
         reachability_vmn_xtls_failed: 1,
+        natType: 'unknown'
       }
     );
   });