Add support for private gateway (#154)

This change adds support for TCPRoutes when using a private gateway
class. This is similar to annotating services today. It also moves the
gateway classes to the Helm chart as it makes things a lot simpler for
the end user as they no longer have to define them.

Signed-off-by: Philip Laine <philip.laine@gmail.com>

internal/gatewayutil/gatewayutil.go

@@ -0,0 +1,64 @@
+package gatewayutil
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"strings"
+
+	"k8s.io/apimachinery/pkg/types"
+	"sigs.k8s.io/controller-runtime/pkg/client"
+	gwv1 "sigs.k8s.io/gateway-api/apis/v1"
+
+	netbirdiov1 "github.com/netbirdio/kubernetes-operator/api/v1"
+)
+
+func GetParentGateway(ctx context.Context, k8sClient client.Client, parent gwv1.ParentReference, namespace, controllerName string) (*gwv1.Gateway, error) {
+	if parent.Namespace != nil {
+		namespace = string(*parent.Namespace)
+	}
+	gw := &gwv1.Gateway{}
+	err := k8sClient.Get(ctx, types.NamespacedName{Namespace: namespace, Name: string(parent.Name)}, gw)
+	if err != nil {
+		return nil, err
+	}
+	gwc := &gwv1.GatewayClass{}
+	err = k8sClient.Get(ctx, client.ObjectKey{Name: string(gw.Spec.GatewayClassName)}, gwc)
+	if err != nil {
+		return nil, err
+	}
+	if string(gwc.Spec.ControllerName) != controllerName {
+		return nil, nil
+	}
+
+	// TODO (phillebaba): Enforce allowed routes in gateway.
+
+	return gw, nil
+}
+
+func GetGatewayRoutingPeer(ctx context.Context, k8sClient client.Client, gw gwv1.Gateway) (*netbirdiov1.NBRoutingPeer, error) {
+	routingPeerName, err := GetRoutingPeerName(gw.Spec.Listeners)
+	if err != nil {
+		return nil, err
+	}
+	nbrp := &netbirdiov1.NBRoutingPeer{}
+	err = k8sClient.Get(ctx, types.NamespacedName{Namespace: gw.Namespace, Name: routingPeerName}, nbrp)
+	if err != nil {
+		return nil, err
+	}
+	return nbrp, nil
+}
+
+func GetRoutingPeerName(listeners []gwv1.Listener) (string, error) {
+	if len(listeners) > 1 {
+		return "", errors.New("netbird Gateway only supports a single listener")
+	}
+	group, kind, ok := strings.Cut(string(listeners[0].Protocol), "/")
+	if !ok {
+		return "", fmt.Errorf("invalid protocol %s, expected gateway.netbird.io/NBRoutingPeer", listeners[0].Protocol)
+	}
+	if group != "gateway.netbird.io" || kind != "NBRoutingPeer" {
+		return "", fmt.Errorf("invalid group %s and kind %s, expected gateway.netbird.io/NBRoutingPeer", group, kind)
+	}
+	return string(listeners[0].Name), nil
+}