fix: shorten VLAN link names to fit into the limit of 15 characters

Fixes #7679

This should be no-op if the link name is <= 10 chars, but with
predictable interface names based on MAC addresses, they have to be
shortened to make some space for VLAN ID.

Signed-off-by: Andrey Smirnov <andrey.smirnov@siderolabs.com>

internal/app/machined/pkg/controllers/network/address_config.go

@@ -293,7 +293,7 @@ func (ctrl *AddressConfigController) processDevicesConfiguration(logger *zap.Log
 				address := network.AddressSpecSpec{
 					Address:     ipPrefix,
 					Scope:       nethelpers.ScopeGlobal,
-					LinkName:    fmt.Sprintf("%s.%d", device.Interface(), vlan.ID()),
+					LinkName:    nethelpers.VLANLinkName(device.Interface(), vlan.ID()),
 					ConfigLayer: network.ConfigMachineConfiguration,
 					Flags:       nethelpers.AddressFlags(nethelpers.AddressPermanent),
 				}

internal/app/machined/pkg/controllers/network/cmdline.go

@@ -351,7 +351,7 @@ func ParseCmdlineNetwork(cmdline *procfs.Cmdline) (CmdlineNetworking, error) {
 			Protocol: nethelpers.VLANProtocol8021Q,
 		}
 
-		vlanName = fmt.Sprintf("%s.%d", phyDevice, vlanID)
+		vlanName = nethelpers.VLANLinkName(phyDevice, uint16(vlanID))
 
 		linkSpecUpdated := false
 

internal/app/machined/pkg/controllers/network/link_config.go

@@ -358,7 +358,7 @@ func (ctrl *LinkConfigController) processDevicesConfiguration(logger *zap.Logger
 		}
 
 		for _, vlan := range device.Vlans() {
-			vlanName := fmt.Sprintf("%s.%d", device.Interface(), vlan.ID())
+			vlanName := nethelpers.VLANLinkName(device.Interface(), vlan.ID())
 
 			linkMap[vlanName] = &network.LinkSpecSpec{
 				Name:        device.Interface(),
@@ -403,7 +403,7 @@ type vlaner interface {
 }
 
 func vlanLink(link *network.LinkSpecSpec, linkName string, vlan vlaner) {
-	link.Name = fmt.Sprintf("%s.%d", linkName, vlan.ID())
+	link.Name = nethelpers.VLANLinkName(linkName, vlan.ID())
 	link.Logical = true
 	link.Up = true
 	link.MTU = vlan.MTU()

internal/app/machined/pkg/controllers/network/operator_config.go

@@ -17,6 +17,7 @@ import (
 	"go.uber.org/zap"
 
 	talosconfig "github.com/siderolabs/talos/pkg/machinery/config/config"
+	"github.com/siderolabs/talos/pkg/machinery/nethelpers"
 	"github.com/siderolabs/talos/pkg/machinery/resources/network"
 )
 
@@ -176,7 +177,7 @@ func (ctrl *OperatorConfigController) Run(ctx context.Context, r controller.Runt
 
 						specs = append(specs, network.OperatorSpecSpec{
 							Operator:  network.OperatorDHCP4,
-							LinkName:  fmt.Sprintf("%s.%d", device.Interface(), vlan.ID()),
+							LinkName:  nethelpers.VLANLinkName(device.Interface(), vlan.ID()),
 							RequireUp: true,
 							DHCP4: network.DHCP4OperatorSpec{
 								RouteMetric: routeMetric,
@@ -193,7 +194,7 @@ func (ctrl *OperatorConfigController) Run(ctx context.Context, r controller.Runt
 
 						specs = append(specs, network.OperatorSpecSpec{
 							Operator:  network.OperatorDHCP6,
-							LinkName:  fmt.Sprintf("%s.%d", device.Interface(), vlan.ID()),
+							LinkName:  nethelpers.VLANLinkName(device.Interface(), vlan.ID()),
 							RequireUp: true,
 							DHCP6: network.DHCP6OperatorSpec{
 								RouteMetric: routeMetric,

internal/app/machined/pkg/controllers/network/operator_vip_config.go

@@ -19,6 +19,7 @@ import (
 
 	"github.com/siderolabs/talos/internal/app/machined/pkg/controllers/network/operator/vip"
 	talosconfig "github.com/siderolabs/talos/pkg/machinery/config/config"
+	"github.com/siderolabs/talos/pkg/machinery/nethelpers"
 	"github.com/siderolabs/talos/pkg/machinery/resources/network"
 )
 
@@ -118,7 +119,7 @@ func (ctrl *OperatorVIPConfigController) Run(ctx context.Context, r controller.R
 
 				for _, vlan := range device.Vlans() {
 					if vlan.VIPConfig() != nil {
-						linkName := fmt.Sprintf("%s.%d", device.Interface(), vlan.ID())
+						linkName := nethelpers.VLANLinkName(device.Interface(), vlan.ID())
 						if spec, specErr := handleVIP(ctx, vlan.VIPConfig(), linkName, logger); specErr != nil {
 							specErrors = multierror.Append(specErrors, specErr)
 						} else {

internal/app/machined/pkg/controllers/network/route_config.go

@@ -307,7 +307,7 @@ func (ctrl *RouteConfigController) processDevicesConfiguration(logger *zap.Logge
 		}
 
 		for _, vlan := range device.Vlans() {
-			vlanLinkName := fmt.Sprintf("%s.%d", device.Interface(), vlan.ID())
+			vlanLinkName := nethelpers.VLANLinkName(device.Interface(), vlan.ID())
 
 			for _, route := range vlan.Routes() {
 				routeSpec, err := convert(vlanLinkName, route)

pkg/machinery/nethelpers/vlan.go

@@ -0,0 +1,32 @@
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+package nethelpers
+
+import (
+	"crypto/sha256"
+	"fmt"
+)
+
+const maxLinkNameLength = 15
+
+// VLANLinkName builds a VLAN link name out of the base device name and VLAN ID.
+//
+// The function takes care of the maximum length of the link name.
+func VLANLinkName(base string, vlanID uint16) string {
+	// VLAN ID is actually 12-bit, so the allowed values are 0-4095.
+	// In ".%d" format, vlanID can be up to 5 characters long.
+	if len(base)+5 <= maxLinkNameLength {
+		return fmt.Sprintf("%s.%d", base, vlanID)
+	}
+
+	// If the base name is too long, we need to truncate it, but simply
+	// truncating might lead to ambiguous link name, so take some hash of the original
+	// name.
+	prefix := base[:4]
+
+	hash := sha256.Sum256([]byte(base))
+
+	return fmt.Sprintf("%s%x.%d", prefix, hash[:(maxLinkNameLength-len(prefix)-5)/2], vlanID)
+}

pkg/machinery/nethelpers/vlan_test.go

@@ -0,0 +1,70 @@
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+package nethelpers_test
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+
+	"github.com/siderolabs/talos/pkg/machinery/nethelpers"
+)
+
+func TestVLANLinkName(t *testing.T) {
+	t.Parallel()
+
+	for _, test := range []struct {
+		base   string
+		vlanID uint16
+
+		expected string
+	}{
+		{
+			base:   "eth0",
+			vlanID: 1,
+
+			expected: "eth0.1",
+		},
+		{
+			base:   "en9s0",
+			vlanID: 4095,
+
+			expected: "en9s0.4095",
+		},
+		{
+			base:   "0123456789",
+			vlanID: 4095,
+
+			expected: "0123456789.4095",
+		},
+		{
+			base:   "enx12545f8c99cd",
+			vlanID: 25,
+
+			expected: "enx1ee6413.25",
+		},
+		{
+			base:   "enx12545f8c99cd",
+			vlanID: 4095,
+
+			expected: "enx1ee6413.4095",
+		},
+		{
+			base:   "enx12545f8c99ce",
+			vlanID: 4095,
+
+			expected: "enx1ef972f.4095",
+		},
+	} {
+		test := test
+
+		t.Run(fmt.Sprintf("%s.%d", test.base, test.vlanID), func(t *testing.T) {
+			t.Parallel()
+
+			assert.Equal(t, test.expected, nethelpers.VLANLinkName(test.base, test.vlanID))
+		})
+	}
+}