Validate API specs before loading them (TykTechnologies#2515)

This adds  validation checks before loading,  only tcp spec check
is implemented to ensure listening port is provided to avod
crashing the gateway.

Other checks can be added in different PR as it is beyond the scope
of this PR

Fixes TykTechnologies#2511
Fixes TykTechnologies#2480

gateway/api_definition.go

@@ -210,6 +210,29 @@ func (s *APISpec) Release() {
 	// release all other resources associated with spec
 }
 
+// Validate returns nil if s is a valid spec and an error stating why the spec is not valid.
+func (s *APISpec) Validate() error {
+	// For tcp services we need to make sure we can bind to the port.
+	switch s.Protocol {
+	case "tcp", "tls":
+		return s.validateTCP()
+	default:
+		return s.validateHTTP()
+	}
+}
+
+func (s *APISpec) validateTCP() error {
+	if s.ListenPort == 0 {
+		return errors.New("missing listening port")
+	}
+	return nil
+}
+
+func (s *APISpec) validateHTTP() error {
+	// NOOP
+	return nil
+}
+
 // APIDefinitionLoader will load an Api definition from a storage
 // system.
 type APIDefinitionLoader struct{}

gateway/proxy_muxer_test.go

@@ -136,6 +136,21 @@ func TestTCPDial_with_service_discovery(t *testing.T) {
 	}
 }
 
+func TestTCP_missing_port(t *testing.T) {
+	ts := StartTest()
+	defer ts.Close()
+	BuildAndLoadAPI(func(spec *APISpec) {
+		spec.Name = "no -listen-port"
+		spec.Protocol = "tcp"
+	})
+	apisMu.RLock()
+	n := len(apiSpecs)
+	apisMu.RUnlock()
+	if n != 0 {
+		t.Errorf("expected 0 apis to be loaded got %d", n)
+	}
+}
+
 func TestCheckPortWhiteList(t *testing.T) {
 	base := config.Global()
 	cases := []struct {

gateway/server.go

@@ -268,10 +268,9 @@ func buildConnStr(resource string) string {
 
 func syncAPISpecs() (int, error) {
 	loader := APIDefinitionLoader{}
-
 	apisMu.Lock()
 	defer apisMu.Unlock()
-
+	var s []*APISpec
 	if config.Global().UseDBAppConfigs {
 		connStr := buildConnStr("/system/apis")
 		tmpSpecs, err := loader.FromDashboardService(connStr, config.Global().NodeSecret)
@@ -280,35 +279,43 @@ func syncAPISpecs() (int, error) {
 			return 0, err
 		}
 
-		apiSpecs = tmpSpecs
+		s = tmpSpecs
 
 		mainLog.Debug("Downloading API Configurations from Dashboard Service")
 	} else if config.Global().SlaveOptions.UseRPC {
 		mainLog.Debug("Using RPC Configuration")
 
 		var err error
-		apiSpecs, err = loader.FromRPC(config.Global().SlaveOptions.RPCKey)
+		s, err = loader.FromRPC(config.Global().SlaveOptions.RPCKey)
 		if err != nil {
 			return 0, err
 		}
 	} else {
-		apiSpecs = loader.FromDir(config.Global().AppPath)
+		s = loader.FromDir(config.Global().AppPath)
 	}
 
-	mainLog.Printf("Detected %v APIs", len(apiSpecs))
+	mainLog.Printf("Detected %v APIs", len(s))
 
 	if config.Global().AuthOverride.ForceAuthProvider {
-		for i := range apiSpecs {
-			apiSpecs[i].AuthProvider = config.Global().AuthOverride.AuthProvider
+		for i := range s {
+			s[i].AuthProvider = config.Global().AuthOverride.AuthProvider
 		}
 	}
 
 	if config.Global().AuthOverride.ForceSessionProvider {
-		for i := range apiSpecs {
-			apiSpecs[i].SessionProvider = config.Global().AuthOverride.SessionProvider
+		for i := range s {
+			s[i].SessionProvider = config.Global().AuthOverride.SessionProvider
 		}
 	}
-
+	var filter []*APISpec
+	for _, v := range s {
+		if err := v.Validate(); err != nil {
+			mainLog.Infof("Skipping loading spec:%q because it failed validation with error:%v", v.Name, err)
+			continue
+		}
+		filter = append(filter, v)
+	}
+	apiSpecs = filter
 	return len(apiSpecs), nil
 }