GODRIVER-3054 Handshake connection should not use legacy for LB

mongo/integration/handshake_test.go

@@ -20,6 +20,7 @@ import (
 	"go.mongodb.org/mongo-driver/mongo/integration/mtest"
 	"go.mongodb.org/mongo-driver/version"
 	"go.mongodb.org/mongo-driver/x/bsonx/bsoncore"
+	"go.mongodb.org/mongo-driver/x/mongo/driver/wiremessage"
 )
 
 func TestHandshakeProse(t *testing.T) {
@@ -199,3 +200,50 @@ func TestHandshakeProse(t *testing.T) {
 		})
 	}
 }
+
+func TestLoadBalancedConnectionHandshake(t *testing.T) {
+	mt := mtest.New(t)
+
+	lbopts := mtest.NewOptions().ClientType(mtest.Proxy).Topologies(
+		mtest.LoadBalanced)
+
+	mt.RunOpts("LB connection handshake uses OP_MSG", lbopts, func(mt *mtest.T) {
+		// Ping the server to ensure the handshake has completed.
+		err := mt.Client.Ping(context.Background(), nil)
+		require.NoError(mt, err, "Ping error: %v", err)
+
+		messages := mt.GetProxiedMessages()
+		handshakeMessage := messages[:1][0]
+
+		hello := handshake.LegacyHello
+		if os.Getenv("REQUIRE_API_VERSION") == "true" {
+			hello = "hello"
+		}
+
+		assert.Equal(mt, hello, handshakeMessage.CommandName)
+		assert.Equal(mt, wiremessage.OpMsg, handshakeMessage.Sent.OpCode)
+	})
+
+	opts := mtest.NewOptions().ClientType(mtest.Proxy).Topologies(
+		mtest.ReplicaSet,
+		mtest.Sharded,
+		mtest.Single,
+		mtest.ShardedReplicaSet)
+
+	mt.RunOpts("non-LB connection handshake uses OP_QUERY", opts, func(mt *mtest.T) {
+		// Ping the server to ensure the handshake has completed.
+		err := mt.Client.Ping(context.Background(), nil)
+		require.NoError(mt, err, "Ping error: %v", err)
+
+		messages := mt.GetProxiedMessages()
+		handshakeMessage := messages[:1][0]
+
+		hello := handshake.LegacyHello
+		if os.Getenv("REQUIRE_API_VERSION") == "true" {
+			hello = "hello"
+		}
+
+		assert.Equal(mt, hello, handshakeMessage.CommandName)
+		assert.Equal(mt, wiremessage.OpQuery, handshakeMessage.Sent.OpCode)
+	})
+}

x/mongo/driver/operation/hello.go

@@ -575,8 +575,8 @@ func (h *Hello) StreamResponse(ctx context.Context, conn driver.StreamerConnecti
 // loadBalanced is False. If this is the case, then the drivers MUST use legacy
 // hello for the first message of the initial handshake with the OP_QUERY
 // protocol
-func isLegacyHandshake(srvAPI *driver.ServerAPIOptions, deployment driver.Deployment) bool {
-	return srvAPI == nil && deployment.Kind() != description.LoadBalanced
+func isLegacyHandshake(srvAPI *driver.ServerAPIOptions, loadbalanced bool) bool {
+	return srvAPI == nil && !loadbalanced
 }
 
 func (h *Hello) createOperation() driver.Operation {
@@ -592,7 +592,7 @@ func (h *Hello) createOperation() driver.Operation {
 		ServerAPI: h.serverAPI,
 	}
 
-	if isLegacyHandshake(h.serverAPI, h.d) {
+	if isLegacyHandshake(h.serverAPI, h.loadBalanced) {
 		op.Legacy = driver.LegacyHandshake
 	}
 
@@ -616,7 +616,7 @@ func (h *Hello) GetHandshakeInformation(ctx context.Context, _ address.Address,
 		ServerAPI: h.serverAPI,
 	}
 
-	if isLegacyHandshake(h.serverAPI, deployment) {
+	if isLegacyHandshake(h.serverAPI, h.loadBalanced) {
 		op.Legacy = driver.LegacyHandshake
 	}