fix: ipv6 is not supported when using dns service discovery

Both server class and monitoring class split the address string on ":" and
assumed it would return address and port tuple. To handle IPv6 addresses
we need to use the number at the end of the address and keep the ipv6
address from being split. I consolidated the logic into ServerDescription
getters.

NODE-2671

src/sdam/monitor.ts

@@ -15,6 +15,7 @@ import {
   ServerHeartbeatSucceededEvent,
   ServerHeartbeatFailedEvent
 } from './events';
+import { Server } from './server';
 
 const kServer = Symbol('server');
 const kMonitorId = Symbol('monitorId');
@@ -47,7 +48,7 @@ class Monitor extends EventEmitter {
   [kCancellationToken]: any;
   [kMonitorId]: any;
 
-  constructor(server: any, options: any) {
+  constructor(server: Server, options: any) {
     super(options);
     this[kServer] = server;
     this[kConnection] = undefined;
@@ -73,12 +74,11 @@ class Monitor extends EventEmitter {
     });
 
     // TODO: refactor this to pull it directly from the pool, requires new ConnectionPool integration
-    const addressParts = server.description.address.split(':');
     const connectOptions = Object.assign(
       {
         id: '<monitor>',
-        host: addressParts[0],
-        port: parseInt(addressParts[1], 10),
+        host: server.description.host,
+        port: server.description.port,
         connectionType: Connection
       },
       server.s.options,

src/sdam/server.ts

@@ -102,11 +102,7 @@ class Server extends EventEmitter {
 
     // create the connection pool
     // NOTE: this used to happen in `connect`, we supported overriding pool options there
-    const addressParts = this.description.address.split(':');
-    const poolOptions = Object.assign(
-      { host: addressParts[0], port: parseInt(addressParts[1], 10) },
-      options
-    );
+    const poolOptions = Object.assign({ host: description.host, port: description.port }, options);
 
     this.s.pool = new ConnectionPool(poolOptions);
     relayEvents(
@@ -150,7 +146,7 @@ class Server extends EventEmitter {
     });
   }
 
-  get description() {
+  get description(): ServerDescription {
     return this.s.description;
   }
 

src/sdam/server_description.ts

@@ -43,7 +43,7 @@ const ISMASTER_FIELDS = [
  * Internal type, not meant to be directly instantiated
  */
 class ServerDescription {
-  address: any;
+  address: string;
   error: any;
   roundTripTime: any;
   lastUpdateTime: any;
@@ -135,6 +135,16 @@ class ServerDescription {
     return WRITABLE_SERVER_TYPES.has(this.type);
   }
 
+  get host() {
+    const chopLength = `:${this.port}`.length;
+    return this.address.slice(0, -chopLength);
+  }
+
+  get port() {
+    const port = this.address.split(':').pop();
+    return port ? Number.parseInt(port, 10) : port;
+  }
+
   /**
    * Determines if another `ServerDescription` is equal to this one per the rules defined
    * in the {@link https://github.com/mongodb/specifications/blob/master/source/server-discovery-and-monitoring/server-discovery-and-monitoring.rst#serverdescription|SDAM spec}

test/unit/sdam/monitoring.test.js

@@ -4,14 +4,13 @@ const { ServerType } = require('../../../src/sdam/common');
 const { Topology } = require('../../../src/sdam/topology');
 const { Monitor } = require('../../../src/sdam/monitor');
 const { expect } = require('chai');
+const { ServerDescription } = require('../../../src/sdam/server_description');
 
 class MockServer {
   constructor(options) {
     this.s = {};
-    this.description = {
-      type: ServerType.Unknown,
-      address: `${options.host}:${options.port}`
-    };
+    this.description = new ServerDescription(`${options.host}:${options.port}`);
+    this.description.type = ServerType.Unknown;
   }
 }
 
@@ -192,6 +191,7 @@ describe('monitoring', function() {
       });
 
       const server = new MockServer(mockServer.address());
+      server.description = new ServerDescription(server.description.address);
       const monitor = new Monitor(server, {
         heartbeatFrequencyMS: 250,
         minHeartbeatFrequencyMS: 50

test/unit/sdam/server_description.test.js

@@ -41,4 +41,10 @@ describe('ServerDescription', function() {
       });
     });
   });
+
+  it('should sensibly parse an ipv6 address', function() {
+    const description = new ServerDescription('abcd:f::abcd:abcd:abcd:abcd:27017');
+    expect(description.host).to.equal('abcd:f::abcd:abcd:abcd:abcd');
+    expect(description.port).to.equal(27017);
+  });
 });