Fix MTU adjustment in case of remote vlan mechanism

The MTU should be updated in connection context based on the base interface MTU

Relates PR: networkservicemesh/sdk-vpp/pull/656

Signed-off-by: Laszlo Kiraly <laszlo.kiraly@est.tech>

pkg/networkservice/mechanisms/vlan/client.go

@@ -30,12 +30,14 @@ import (
 	"github.com/networkservicemesh/api/pkg/api/networkservice"
 	"github.com/networkservicemesh/api/pkg/api/networkservice/mechanisms/cls"
 	vlanmech "github.com/networkservicemesh/api/pkg/api/networkservice/mechanisms/vlan"
+	"github.com/networkservicemesh/sdk/pkg/networkservice/core/chain"
 	"github.com/networkservicemesh/sdk/pkg/networkservice/core/next"
 	"github.com/networkservicemesh/sdk/pkg/tools/log"
 	"github.com/networkservicemesh/sdk/pkg/tools/postpone"
 	"github.com/pkg/errors"
 	"google.golang.org/grpc"
 
+	"github.com/networkservicemesh/sdk-ovs/pkg/networkservice/mechanisms/vlan/mtu"
 	"github.com/networkservicemesh/sdk-ovs/pkg/tools/ifnames"
 	ovsutil "github.com/networkservicemesh/sdk-ovs/pkg/tools/utils"
 )
@@ -51,7 +53,10 @@ type vlanClient struct {
 
 // NewClient returns a client chain element implementing VLAN breakout for NS client
 func NewClient(bridgeName string, l2Connections map[string]*ovsutil.L2ConnectionPoint) networkservice.NetworkServiceClient {
-	return &vlanClient{bridgeName: bridgeName, l2Connections: l2Connections}
+	return chain.NewNetworkServiceClient(
+		mtu.NewClient(l2Connections),
+		&vlanClient{bridgeName: bridgeName, l2Connections: l2Connections},
+	)
 }
 
 func (c *vlanClient) Request(ctx context.Context, request *networkservice.NetworkServiceRequest, opts ...grpc.CallOption) (*networkservice.Connection, error) {

pkg/networkservice/mechanisms/vlan/mtu/client.go

@@ -0,0 +1,89 @@
+// Copyright (c) 2022 Nordix Foundation.
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at:
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package mtu
+
+import (
+	"context"
+
+	"github.com/pkg/errors"
+	"google.golang.org/grpc"
+	"google.golang.org/protobuf/types/known/emptypb"
+
+	"github.com/networkservicemesh/api/pkg/api/networkservice"
+	"github.com/networkservicemesh/api/pkg/api/networkservice/mechanisms/vlan"
+	"github.com/networkservicemesh/sdk/pkg/networkservice/core/next"
+	"github.com/networkservicemesh/sdk/pkg/tools/log"
+	"github.com/networkservicemesh/sdk/pkg/tools/postpone"
+
+	ovsutil "github.com/networkservicemesh/sdk-ovs/pkg/tools/utils"
+)
+
+const (
+	viaLabel = "via"
+)
+
+type mtuClient struct {
+	l2Connections map[string]*ovsutil.L2ConnectionPoint
+}
+
+// NewClient - returns client chain element to manage vlan MTU
+func NewClient(l2Connections map[string]*ovsutil.L2ConnectionPoint) networkservice.NetworkServiceClient {
+	return &mtuClient{
+		l2Connections: l2Connections,
+	}
+}
+
+func (m *mtuClient) Request(ctx context.Context, request *networkservice.NetworkServiceRequest, opts ...grpc.CallOption) (*networkservice.Connection, error) {
+	postponeCtxFunc := postpone.ContextWithValues(ctx)
+	logger := log.FromContext(ctx).WithField("vlanClient", "Request")
+
+	conn, err := next.Client(ctx).Request(ctx, request, opts...)
+	if err != nil {
+		return nil, err
+	}
+
+	if mechanism := vlan.ToMechanism(conn.GetMechanism()); mechanism != nil {
+		viaSelector, ok := conn.GetLabels()[viaLabel]
+		if !ok {
+			return conn, nil
+		}
+		l2Point, ok := m.l2Connections[viaSelector]
+		if !ok {
+			return conn, nil
+		}
+		localMTU, err := getMTU(l2Point, logger)
+		if err != nil {
+			closeCtx, cancelClose := postponeCtxFunc()
+			defer cancelClose()
+			if _, closeErr := m.Close(closeCtx, conn, opts...); closeErr != nil {
+				err = errors.Wrapf(err, "connection closed with error: %s", closeErr.Error())
+			}
+			return nil, err
+		}
+		if localMTU > 0 && (conn.GetContext().GetMTU() > localMTU || conn.GetContext().GetMTU() == 0) {
+			if conn.GetContext() == nil {
+				conn.Context = &networkservice.ConnectionContext{}
+			}
+			conn.GetContext().MTU = localMTU
+		}
+	}
+	return conn, nil
+}
+
+func (m *mtuClient) Close(ctx context.Context, conn *networkservice.Connection, opts ...grpc.CallOption) (*emptypb.Empty, error) {
+	return next.Client(ctx).Close(ctx, conn, opts...)
+}

pkg/networkservice/mechanisms/vlan/mtu/common.go

@@ -0,0 +1,42 @@
+// Copyright (c) 2022 Nordix Foundation.
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at:
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package mtu
+
+import (
+	"github.com/networkservicemesh/sdk/pkg/tools/log"
+	"github.com/pkg/errors"
+	"github.com/vishvananda/netlink"
+
+	ovsutil "github.com/networkservicemesh/sdk-ovs/pkg/tools/utils"
+)
+
+func getMTU(l2CP *ovsutil.L2ConnectionPoint, logger log.Logger) (uint32, error) {
+	if l2CP.Interface == "" {
+		return 0, nil
+	}
+	link, err := netlink.LinkByName(l2CP.Interface)
+	if err != nil {
+		return 0, nil
+	}
+	mtu := link.Attrs().MTU
+	logger.Infof("Get MTU of interface %s  %d", l2CP.Interface, mtu)
+	if mtu >= 0 && mtu <= 65535 {
+		return uint32(mtu), nil
+	}
+
+	return 0, errors.New("invalid MTU value")
+}

pkg/networkservice/mechanisms/vlan/mtu/doc.go

@@ -0,0 +1,18 @@
+// Copyright (c) 2022 Nordix Foundation.
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at:
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package mtu computes the mtu for the vlan interface and adds it to context
+package mtu