[NET-6417] Add validation of MeshGateway name + listeners (#20425)

* Add validation of MeshGateway name + listeners

* Adds test for ValidateMeshGateway

* Fixes data fetcher test for gatewayproxy

---------

Co-authored-by: Nathan Coleman <nathan.coleman@hashicorp.com>

internal/mesh/internal/controllers/gatewayproxy/fetcher/data_fetcher_test.go

@@ -69,9 +69,14 @@ func (suite *dataFetcherSuite) setupWithTenancy(tenancy *pbresource.Tenancy) {
 		).
 		Write(suite.T(), suite.client)
 
-	suite.meshGateway = resourcetest.Resource(pbmesh.MeshGatewayType, "mesh-gateway-1").
+	suite.meshGateway = resourcetest.Resource(pbmesh.MeshGatewayType, "mesh-gateway").
 		WithData(suite.T(), &pbmesh.MeshGateway{
 			GatewayClassName: "gateway-class-1",
+			Listeners: []*pbmesh.MeshGatewayListener{
+				{
+					Name: "wan",
+				},
+			},
 		}).
 		Write(suite.T(), suite.client)
 

internal/mesh/internal/types/mesh_gateway.go

@@ -4,6 +4,12 @@
 package types
 
 import (
+	"errors"
+	"fmt"
+
+	"github.com/hashicorp/go-multierror"
+
+	"github.com/hashicorp/consul/internal/mesh/internal/controllers/meshgateways"
 	"github.com/hashicorp/consul/internal/resource"
 	pbmesh "github.com/hashicorp/consul/proto-public/pbmesh/v2beta1"
 )
@@ -15,6 +21,24 @@ func RegisterMeshGateway(r resource.Registry) {
 		Scope:    resource.ScopePartition,
 		ACLs:     nil, // TODO NET-6416
 		Mutate:   nil, // TODO NET-6418
-		Validate: nil, // TODO NET-6417
+		Validate: resource.DecodeAndValidate(validateMeshGateway),
 	})
 }
+
+func validateMeshGateway(res *DecodedMeshGateway) error {
+	var merr error
+
+	if res.GetId().GetName() != meshgateways.GatewayName {
+		merr = multierror.Append(merr, fmt.Errorf("invalid gateway name, must be %q", meshgateways.GatewayName))
+	}
+
+	if len(res.GetData().Listeners) != 1 {
+		merr = multierror.Append(merr, errors.New("invalid listeners, must have exactly one listener"))
+	}
+
+	if len(res.GetData().Listeners) > 0 && (res.GetData().Listeners[0].GetName() != meshgateways.WANPortName) {
+		merr = multierror.Append(merr, fmt.Errorf("invalid listener name, must be %q", meshgateways.WANPortName))
+	}
+
+	return merr
+}

internal/mesh/internal/types/mesh_gateway_test.go

@@ -0,0 +1,97 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: BUSL-1.1
+
+package types
+
+import (
+	"github.com/hashicorp/consul/internal/resource"
+	"testing"
+
+	"github.com/hashicorp/consul/internal/resource/resourcetest"
+	pbmesh "github.com/hashicorp/consul/proto-public/pbmesh/v2beta1"
+	"github.com/hashicorp/consul/sdk/testutil"
+	"github.com/stretchr/testify/require"
+)
+
+func TestValidateMeshGateway(t *testing.T) {
+	type testcase struct {
+		mgwName   string
+		mgw       *pbmesh.MeshGateway
+		expectErr string
+	}
+
+	run := func(t *testing.T, tc testcase) {
+		res := resourcetest.Resource(pbmesh.MeshGatewayType, tc.mgwName).
+			WithData(t, tc.mgw).
+			Build()
+
+		err := resource.DecodeAndValidate(validateMeshGateway)(res)
+
+		if tc.expectErr == "" {
+			require.NoError(t, err)
+		} else {
+			testutil.RequireErrorContains(t, err, tc.expectErr)
+		}
+	}
+
+	cases := map[string]testcase{
+		"happy path": {
+			mgwName: "mesh-gateway",
+			mgw: &pbmesh.MeshGateway{
+				Listeners: []*pbmesh.MeshGatewayListener{
+					{
+						Name: "wan",
+					},
+				},
+			},
+			expectErr: "",
+		},
+		"wrong name for mesh-gateway": {
+			mgwName: "my-mesh-gateway",
+			mgw: &pbmesh.MeshGateway{
+				Listeners: []*pbmesh.MeshGatewayListener{
+					{
+						Name: "wan",
+					},
+				},
+			},
+			expectErr: "invalid gateway name, must be \"mesh-gateway\"",
+		},
+		"too many listeners on mesh-gateway": {
+			mgwName: "mesh-gateway",
+			mgw: &pbmesh.MeshGateway{
+				Listeners: []*pbmesh.MeshGatewayListener{
+					{
+						Name: "obi",
+					},
+					{
+						Name: "wan",
+					},
+				},
+			},
+			expectErr: "invalid listeners, must have exactly one listener",
+		},
+		"zero listeners on mesh-gateway": {
+			mgwName:   "mesh-gateway",
+			mgw:       &pbmesh.MeshGateway{},
+			expectErr: "invalid listeners, must have exactly one listener",
+		},
+		"incorrect listener name on mesh-gateway": {
+			mgwName: "mesh-gateway",
+			mgw: &pbmesh.MeshGateway{
+				Listeners: []*pbmesh.MeshGatewayListener{
+					{
+						Name: "kenobi",
+					},
+				},
+			},
+			expectErr: "invalid listener name, must be \"wan\"",
+		},
+	}
+
+	for name, tc := range cases {
+		t.Run(name, func(t *testing.T) {
+			run(t, tc)
+		})
+	}
+}