fix(NODE-3413): accept tls=false in mongodb+srv connection strings (#2886)

Author: addaleax

src/connection_string.ts

@@ -232,7 +232,9 @@ export function parseOptions(
   if (isSRV) {
     // SRV Record is resolved upon connecting
     mongoOptions.srvHost = hosts[0];
-    options.tls = true;
+    if (!url.searchParams.has('tls') && !url.searchParams.has('ssl')) {
+      options.tls = true;
+    }
   }
 
   const urlOptions = new CaseInsensitiveMap();

test/unit/core/mongodb_srv.test.js

@@ -38,8 +38,14 @@ describe('mongodb+srv', function () {
                 expect(result).to.exist;
                 // Implicit SRV options must be set.
                 expect(options.directConnection).to.be.false;
-                expect(options.tls).to.be.true;
                 const testOptions = test[1].options;
+                if (testOptions && 'tls' in testOptions) {
+                  expect(options).to.have.property('tls', testOptions.tls);
+                } else if (testOptions && 'ssl' in testOptions) {
+                  expect(options).to.have.property('tls', testOptions.ssl);
+                } else {
+                  expect(options.tls).to.be.true;
+                }
                 if (testOptions && testOptions.replicaSet) {
                   expect(options).to.have.property('replicaSet', testOptions.replicaSet);
                 }

test/unit/mongo_client_options.test.js

@@ -229,6 +229,19 @@ describe('MongoOptions', function () {
   it('srvHost saved to options for later resolution', function () {
     const options = parseOptions('mongodb+srv://server.example.com/');
     expect(options).has.property('srvHost', 'server.example.com');
+    expect(options).has.property('tls', true);
+  });
+
+  it('ssl= can be used to set tls=false', function () {
+    const options = parseOptions('mongodb+srv://server.example.com/?ssl=false');
+    expect(options).has.property('srvHost', 'server.example.com');
+    expect(options).has.property('tls', false);
+  });
+
+  it('tls= can be used to set tls=false', function () {
+    const options = parseOptions('mongodb+srv://server.example.com/?tls=false');
+    expect(options).has.property('srvHost', 'server.example.com');
+    expect(options).has.property('tls', false);
   });
 
   it('supports ReadPreference option in url', function () {