Add call validation, and fix flaky call validation tests

Previously, we only validated that a timeout was set, not that a
servicename was specified when making an outbound call.

Add validation, and do it before we get a connection. This avoids
creating a connection that will not be used.

Previously, we would create a connection, do validation, and close the
connection immediately. On the inbound side, this led to a new
connection that was closed almost immediately, and so sometimes the test
would cause a:
"Failed to add connection to peer" "connection is in an invalid state"

By doing validation before we create a connection we make TestNoTimeout
less flaky, while also returning errors earlier and faster.

connection_test.go

@@ -314,13 +314,24 @@ func TestNoTimeout(t *testing.T) {
 
 		ctx := context.Background()
 		_, _, _, err := raw.Call(ctx, ts.Server(), ts.HostPort(), "svc", "Echo", []byte("Headers"), []byte("Body"))
-		require.NotNil(t, err)
 		assert.Equal(t, ErrTimeoutRequired, err)
 
 		ts.AssertRelayStats(relay.NewMockStats())
 	})
 }
 
+func TestNoServiceNaming(t *testing.T) {
+	testutils.WithTestServer(t, nil, func(ts *testutils.TestServer) {
+		ctx, cancel := NewContext(time.Second)
+		defer cancel()
+
+		_, _, _, err := raw.Call(ctx, ts.Server(), ts.HostPort(), "", "Echo", []byte("Headers"), []byte("Body"))
+		assert.Equal(t, ErrNoServiceName, err)
+
+		ts.AssertRelayStats(relay.NewMockStats())
+	})
+}
+
 func TestServerBusy(t *testing.T) {
 	testutils.WithTestServer(t, nil, func(ts *testutils.TestServer) {
 		ts.Register(ErrorHandlerFunc(func(ctx context.Context, call *InboundCall) error {

outbound.go

@@ -47,8 +47,9 @@ func (c *Connection) beginCall(ctx context.Context, serviceName, methodName stri
 	}
 
 	deadline, ok := ctx.Deadline()
-	// No deadline was set, we should not support no deadlines.
 	if !ok {
+		// This case is handled by validateCall, so we should
+		// never get here.
 		return nil, ErrTimeoutRequired
 	}
 	timeToLive := deadline.Sub(now)
@@ -214,10 +215,6 @@ func (call *OutboundCall) createStatsTags(connectionTags map[string]string, call
 
 // writeMethod writes the method (arg1) to the call
 func (call *OutboundCall) writeMethod(method []byte) error {
-	if len(method) > maxMethodSize {
-		return call.failed(ErrMethodTooLarge)
-	}
-
 	call.statsReporter.IncCounter("outbound.calls.send", call.commonStatsTags, 1)
 	return NewArgWriter(call.arg1Writer()).Write(method)
 }
@@ -369,3 +366,19 @@ func (response *OutboundCallResponse) doneReading(unexpected error) {
 
 	response.mex.shutdown()
 }
+
+func validateCall(ctx context.Context, serviceName, methodName string, callOpts *CallOptions) error {
+	if serviceName == "" {
+		return ErrNoServiceName
+	}
+
+	if len(methodName) > maxMethodSize {
+		return ErrMethodTooLarge
+	}
+
+	if _, ok := ctx.Deadline(); !ok {
+		return ErrTimeoutRequired
+	}
+
+	return nil
+}

peer.go

@@ -455,6 +455,10 @@ func (p *Peer) BeginCall(ctx context.Context, serviceName, methodName string, ca
 	}
 	callOptions.RequestState.AddSelectedPeer(p.HostPort())
 
+	if err := validateCall(ctx, serviceName, methodName, callOptions); err != nil {
+		return nil, err
+	}
+
 	conn, err := p.GetConnection(ctx)
 	if err != nil {
 		return nil, err