Gateway API: support TLS termination with TLSRoute/TCPRoute (#5481)

Adds support for TLS termination with the TLS
listener protocol. Envoy is configured to terminate
TLS and then to proxy TCP traffic to the backend.

Closes #5461.

Signed-off-by: Steve Kriss <krisss@vmware.com>

changelogs/unreleased/5481-skriss-minor.md

@@ -0,0 +1,22 @@
+## Gateway API: Support TLS termination with TLSRoute and TCPRoute
+
+Contour now supports using TLSRoute and TCPRoute in combination with TLS termination.
+To use this feature, create a Gateway with a Listener like the following:
+
+```yaml
+- name: tls-listener
+  protocol: TLS
+  port: 5000
+  tls:
+    mode: Terminate
+    certificateRefs:
+    - name: tls-cert-secret
+  allowedRoutes:
+    namespaces:
+      from: All
+---
+```
+
+It is then possible to attach either 1+ TLSRoutes, or a single TCPRoute, to this Listener.
+If using TLSRoute, traffic can be routed to a different backend based on SNI.
+If using TCPRoute, all traffic is forwarded to the backend referenced in the route.

internal/dag/builder_test.go

@@ -921,7 +921,7 @@ func TestDAGInsertGatewayAPI(t *testing.T) {
 			},
 			want: listeners(),
 		},
-		"TLS Listener with TLS.Mode=Terminate is invalid": {
+		"TLS Listener with TLS.Mode=Terminate is invalid if certificateRef is not specified": {
 			gatewayclass: validClass,
 			gateway: &gatewayapi_v1beta1.Gateway{
 				ObjectMeta: metav1.ObjectMeta{
@@ -935,9 +935,6 @@ func TestDAGInsertGatewayAPI(t *testing.T) {
 						Protocol: gatewayapi_v1beta1.TLSProtocolType,
 						TLS: &gatewayapi_v1beta1.GatewayTLSConfig{
 							Mode: ref.To(gatewayapi_v1beta1.TLSModeTerminate),
-							CertificateRefs: []gatewayapi_v1beta1.SecretObjectReference{
-								gatewayapi.CertificateRef(sec1.Name, sec1.Namespace),
-							},
 						},
 						AllowedRoutes: &gatewayapi_v1beta1.AllowedRoutes{
 							Namespaces: &gatewayapi_v1beta1.RouteNamespaces{

internal/dag/gatewayapi_processor.go

@@ -544,25 +544,27 @@ func (p *GatewayAPIProcessor) computeListener(
 	case gatewayapi_v1beta1.TLSProtocolType:
 		// The TLS protocol is used for TCP traffic encrypted with TLS.
 		// Gateway API allows TLS to be either terminated at the proxy
-		// or passed through to the backend, but the former requires using
-		// TCPRoute to route traffic since the underlying protocol is TCP
-		// not HTTP, which Contour doesn't support. Therefore, we only
-		// support "Passthrough" with the TLS protocol, which requires
-		// the use of TLSRoute to route to backends since the traffic is
-		// still encrypted.
-
+		// or passed through to the backend.
 		if listener.TLS == nil {
 			addInvalidListenerCondition(fmt.Sprintf("Listener.TLS is required when protocol is %q.", listener.Protocol))
 			return false, nil
 		}
 
-		if listener.TLS.Mode == nil || *listener.TLS.Mode != gatewayapi_v1beta1.TLSModePassthrough {
-			addInvalidListenerCondition(fmt.Sprintf("Listener.TLS.Mode must be %q when protocol is %q.", gatewayapi_v1beta1.TLSModePassthrough, listener.Protocol))
-			return false, nil
-		}
-
-		if len(listener.TLS.CertificateRefs) != 0 {
-			addInvalidListenerCondition(fmt.Sprintf("Listener.TLS.CertificateRefs cannot be defined when Listener.TLS.Mode is %q.", gatewayapi_v1beta1.TLSModePassthrough))
+		switch {
+		case listener.TLS.Mode == nil || *listener.TLS.Mode == gatewayapi_v1beta1.TLSModeTerminate:
+			// Resolve the TLS secret.
+			if listenerSecret = p.resolveListenerSecret(listener.TLS.CertificateRefs, string(listener.Name), gwAccessor); listenerSecret == nil {
+				// If TLS was configured on the Listener, but the secret ref is invalid, don't allow any
+				// routes to be bound to this listener since it can't serve TLS traffic.
+				return false, nil
+			}
+		case *listener.TLS.Mode == gatewayapi_v1beta1.TLSModePassthrough:
+			if len(listener.TLS.CertificateRefs) != 0 {
+				addInvalidListenerCondition(fmt.Sprintf("Listener.TLS.CertificateRefs cannot be defined when Listener.TLS.Mode is %q.", gatewayapi_v1beta1.TLSModePassthrough))
+				return false, nil
+			}
+		default:
+			addInvalidListenerCondition(fmt.Sprintf("Listener.TLS.Mode must be %q or %q.", gatewayapi_v1beta1.TLSModeTerminate, gatewayapi_v1beta1.TLSModePassthrough))
 			return false, nil
 		}
 	}
@@ -588,7 +590,7 @@ func (p *GatewayAPIProcessor) getListenerRouteKinds(listener gatewayapi_v1beta1.
 		case gatewayapi_v1beta1.HTTPSProtocolType:
 			return []gatewayapi_v1beta1.Kind{KindHTTPRoute, KindGRPCRoute}
 		case gatewayapi_v1beta1.TLSProtocolType:
-			return []gatewayapi_v1beta1.Kind{KindTLSRoute}
+			return []gatewayapi_v1beta1.Kind{KindTLSRoute, KindTCPRoute}
 		case gatewayapi_v1beta1.TCPProtocolType:
 			return []gatewayapi_v1beta1.Kind{KindTCPRoute}
 		}
@@ -627,7 +629,7 @@ func (p *GatewayAPIProcessor) getListenerRouteKinds(listener gatewayapi_v1beta1.
 			)
 			continue
 		}
-		if routeKind.Kind == KindTCPRoute && listener.Protocol != gatewayapi_v1beta1.TCPProtocolType {
+		if routeKind.Kind == KindTCPRoute && listener.Protocol != gatewayapi_v1beta1.TCPProtocolType && listener.Protocol != gatewayapi_v1beta1.TLSProtocolType {
 			gwAccessor.AddListenerCondition(
 				string(listener.Name),
 				gatewayapi_v1beta1.ListenerConditionResolvedRefs,
@@ -1654,7 +1656,13 @@ func (p *GatewayAPIProcessor) computeTCPRouteForListener(route *gatewayapi_v1alp
 		return false
 	}
 
-	p.dag.Listeners[listener.dagListenerName].TCPProxy = &proxy
+	if listener.tlsSecret != nil {
+		secure := p.dag.EnsureSecureVirtualHost(listener.dagListenerName, "*")
+		secure.Secret = listener.tlsSecret
+		secure.TCPProxy = &proxy
+	} else {
+		p.dag.Listeners[listener.dagListenerName].TCPProxy = &proxy
+	}
 
 	return true
 }