From 4651c5b41a4c9aa3a71a06eec8dbddd415d511d5 Mon Sep 17 00:00:00 2001
From: Manoj Surudwad <manoj.surudwad@nutanix.com>
Date: Mon, 9 Dec 2024 17:05:26 +0530
Subject: [PATCH] fix: validates CONTROL_PLANE_ENDPOINT_IP and NUTANIX_ENDPOINT
 are distinct

---
 pkg/webhook/cluster/nutanix_validator.go      | 123 ++++++++++++++++++
 .../cluster/{vaiidator.go => validator.go}    |   1 +
 2 files changed, 124 insertions(+)
 create mode 100644 pkg/webhook/cluster/nutanix_validator.go
 rename pkg/webhook/cluster/{vaiidator.go => validator.go} (89%)

diff --git a/pkg/webhook/cluster/nutanix_validator.go b/pkg/webhook/cluster/nutanix_validator.go
new file mode 100644
index 000000000..7eee86997
--- /dev/null
+++ b/pkg/webhook/cluster/nutanix_validator.go
@@ -0,0 +1,123 @@
+// Copyright 2024 Nutanix. All rights reserved.
+// SPDX-License-Identifier: Apache-2.0
+
+package cluster
+
+import (
+	"context"
+	"fmt"
+	"net"
+	"net/http"
+	"net/url"
+
+	v1 "k8s.io/api/admission/v1"
+	clusterv1 "sigs.k8s.io/cluster-api/api/v1beta1"
+	ctrlclient "sigs.k8s.io/controller-runtime/pkg/client"
+	"sigs.k8s.io/controller-runtime/pkg/webhook/admission"
+
+	"github.com/nutanix-cloud-native/cluster-api-runtime-extensions-nutanix/api/v1alpha1"
+	"github.com/nutanix-cloud-native/cluster-api-runtime-extensions-nutanix/api/variables"
+	"github.com/nutanix-cloud-native/cluster-api-runtime-extensions-nutanix/common/pkg/capi/utils"
+)
+
+type nutanixValidator struct {
+	client  ctrlclient.Client
+	decoder admission.Decoder
+}
+
+func NewNutanixValidator(
+	client ctrlclient.Client, decoder admission.Decoder,
+) *nutanixValidator {
+	return &nutanixValidator{
+		client:  client,
+		decoder: decoder,
+	}
+}
+
+func (a *nutanixValidator) Validator() admission.HandlerFunc {
+	return a.validate
+}
+
+func (a *nutanixValidator) validate(
+	ctx context.Context,
+	req admission.Request,
+) admission.Response {
+	if req.Operation == v1.Delete {
+		return admission.Allowed("")
+	}
+
+	cluster := &clusterv1.Cluster{}
+	err := a.decoder.Decode(req, cluster)
+	if err != nil {
+		return admission.Errored(http.StatusBadRequest, err)
+	}
+
+	if cluster.Spec.Topology == nil {
+		return admission.Allowed("")
+	}
+
+	if utils.GetProvider(cluster) != "nutanix" {
+		return admission.Allowed("")
+	}
+
+	clusterConfig, err := variables.UnmarshalClusterConfigVariable(cluster.Spec.Topology.Variables)
+	if err != nil {
+		return admission.Denied(
+			fmt.Errorf("failed to unmarshal cluster topology variable %q: %w",
+				v1alpha1.ClusterConfigVariableName,
+				err).Error(),
+		)
+	}
+
+	if clusterConfig.Nutanix != nil {
+		// Check if Prism Central and Control Plane IP are same.
+		if err := checkIfPrismCentralAndControlPlaneIPSame(
+			clusterConfig.Nutanix.PrismCentralEndpoint.URL,
+			clusterConfig.Nutanix.ControlPlaneEndpoint.Host,
+		); err != nil {
+			return admission.Denied(err.Error())
+		}
+	}
+
+	return admission.Allowed("")
+}
+
+// checkIfPrismCentralAndControlPlaneIPSame checks if Prism Central and Control Plane IP are same.
+// It compares strictly IP addresses(no FQDN) and doesn't involve any network calls.
+// This is a temporary check until we have a better way to handle this by reserving IPs
+// using IPAM provider.
+func checkIfPrismCentralAndControlPlaneIPSame(
+	pcRawURL string,
+	controlPlaneEndpointHost string,
+) error {
+	controlPlaneEndpointIP := net.ParseIP(controlPlaneEndpointHost)
+	if controlPlaneEndpointIP == nil {
+		// controlPlaneEndpointIP is strictly accepted as an IP address from user so
+		// if it is not an IP address, it is invalid.
+		return fmt.Errorf("invalid Nutanix control plane endpoint IP %q",
+			controlPlaneEndpointHost)
+	}
+
+	pcURL, err := url.ParseRequestURI(pcRawURL)
+	if err != nil {
+		return fmt.Errorf("failed to parse Prism Central URL %q: %w",
+			pcURL,
+			err)
+	}
+
+	pcHost, _, err := net.SplitHostPort(pcURL.Host)
+	if err != nil {
+		return fmt.Errorf("failed to parse Prism Central host %q: %w",
+			pcURL.Host,
+			err)
+	}
+
+	pcIP := net.ParseIP(pcHost)
+	// PC URL can contain IP/FQDN, so compare only if PC is an IP address.
+	if pcIP != nil && pcIP.Equal(controlPlaneEndpointIP) {
+		return fmt.Errorf("prism central and control plane endpoint cannot have the same IP %q",
+			pcIP)
+	}
+
+	return nil
+}
diff --git a/pkg/webhook/cluster/vaiidator.go b/pkg/webhook/cluster/validator.go
similarity index 89%
rename from pkg/webhook/cluster/vaiidator.go
rename to pkg/webhook/cluster/validator.go
index 3eae0a7dc..adbddae27 100644
--- a/pkg/webhook/cluster/vaiidator.go
+++ b/pkg/webhook/cluster/validator.go
@@ -11,5 +11,6 @@ import (
 func NewValidator(client ctrlclient.Client, decoder admission.Decoder) admission.Handler {
 	return admission.MultiValidatingHandler(
 		NewClusterUUIDLabeler(client, decoder).Validator(),
+		NewNutanixValidator(client, decoder).Validator(),
 	)
 }