feat: implement multicast setting

Add a multicast option to LinkSpec that can be configured to explicitly declare the state of the multicast flag.

Signed-off-by: Bryan Lee <me@bryanl.ee>
(cherry picked from commit 6db06f4)

Author: 6ixfalls

api/resource/definitions/network/network.proto

@@ -251,6 +251,7 @@ message LinkSpecSpec {
   WireguardSpec wireguard = 13;
   talos.resource.definitions.enums.NetworkConfigLayer config_layer = 14;
   bytes hardware_address = 15;
+  bool multicast = 16;
 }
 
 // LinkStatusSpec describes status of rendered secrets.

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

@@ -634,6 +634,27 @@ func (ctrl *LinkSpecController) syncLink(ctx context.Context, r controller.Runti
 			logger.Info("changed hardware address for the link", zap.String("hwaddr", net.HardwareAddr(link.TypedSpec().HardwareAddress).String()))
 		}
 
+		// sync multicast flag if it's set in the spec
+		if link.TypedSpec().Multicast != nil && ((existing.Flags&unix.IFF_MULTICAST == unix.IFF_MULTICAST) != *link.TypedSpec().Multicast) {
+			flags := uint32(0)
+
+			if *link.TypedSpec().Multicast {
+				flags = unix.IFF_MULTICAST
+			}
+
+			if err := conn.Link.Set(&rtnetlink.LinkMessage{
+				Family: existing.Family,
+				Type:   existing.Type,
+				Index:  existing.Index,
+				Flags:  flags,
+				Change: unix.IFF_MULTICAST,
+			}); err != nil {
+				return fmt.Errorf("error changing multicast flag for %q: %w", link.TypedSpec().Name, err)
+			}
+
+			logger.Info("changed multicast flag for the link", zap.Bool("multicast", *link.TypedSpec().Multicast))
+		}
+
 		// sync master index (for links which are bridge or bond slaves)
 		var masterIndex uint32
 

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

@@ -22,6 +22,7 @@ import (
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 	"github.com/stretchr/testify/suite"
+	"golang.org/x/sys/unix"
 	"golang.zx2c4.com/wireguard/wgctrl/wgtypes"
 
 	networkadapter "github.com/siderolabs/talos/internal/app/machined/pkg/adapters/network"
@@ -94,6 +95,35 @@ func (suite *LinkSpecSuite) TestDummy() {
 		asrt.Equal(newHardwareAddr, net.HardwareAddr(r.TypedSpec().HardwareAddr))
 	})
 
+	// check default multicast behavior (disabled on dummy interfaces)
+	ctest.AssertResource(suite, dummyInterface, func(r *network.LinkStatus, asrt *assert.Assertions) {
+		asrt.Equal(r.TypedSpec().Flags&unix.IFF_MULTICAST == unix.IFF_MULTICAST, false)
+	})
+
+	// attempt to change multicast flag
+	ctest.UpdateWithConflicts(suite, dummy, func(r *network.LinkSpec) error {
+		r.TypedSpec().Multicast = new(bool)
+		*r.TypedSpec().Multicast = true
+
+		return nil
+	})
+
+	ctest.AssertResource(suite, dummyInterface, func(r *network.LinkStatus, asrt *assert.Assertions) {
+		asrt.Equal(r.TypedSpec().Flags&unix.IFF_MULTICAST == unix.IFF_MULTICAST, true)
+	})
+
+	// attempt to disable multicast
+	ctest.UpdateWithConflicts(suite, dummy, func(r *network.LinkSpec) error {
+		r.TypedSpec().Multicast = new(bool)
+		*r.TypedSpec().Multicast = false
+
+		return nil
+	})
+
+	ctest.AssertResource(suite, dummyInterface, func(r *network.LinkStatus, asrt *assert.Assertions) {
+		asrt.Equal(r.TypedSpec().Flags&unix.IFF_MULTICAST == unix.IFF_MULTICAST, false)
+	})
+
 	suite.Require().NoError(suite.State().TeardownAndDestroy(suite.Ctx(), dummy.Metadata()))
 
 	ctest.AssertNoResource[*network.LinkSpec](suite, dummyInterface)

pkg/machinery/api/resource/definitions/network/network.pb.go

@@ -70,7 +70,7 @@ const (
 	LinkAllMulti                          // ALLMULTI
 	LinkMaster                            // MASTER
 	LinkSlave                             // SLAVE
-	LinkMulticase                         // MULTICAST
+	LinkMulticast                         // MULTICAST
 	LinkPortsel                           // PORTSEL
 	LinKAutoMedia                         // AUTOMEDIA
 	LinkDynamic                           // DYNAMIC

pkg/machinery/api/resource/definitions/network/network_vtproto.pb.go

@@ -64,6 +64,9 @@ type LinkSpecSpec struct {
 
 	// Configuration layer.
 	ConfigLayer ConfigLayer `yaml:"layer" protobuf:"14"`
+
+	// Multicast indicates whether the multicast flag should be set on the interface to the value.
+	Multicast *bool `yaml:"multicast,omitempty" protobuf:"16"`
 }
 
 // BondSlave contains a bond's master name and slave index.

pkg/machinery/nethelpers/arpalltargets_enumer.go

@@ -8781,6 +8781,7 @@ LinkSpecSpec describes spec for the link.
 | wireguard | [WireguardSpec](#talos.resource.definitions.network.WireguardSpec) |  |  |
 | config_layer | [talos.resource.definitions.enums.NetworkConfigLayer](#talos.resource.definitions.enums.NetworkConfigLayer) |  |  |
 | hardware_address | [bytes](#bytes) |  |  |
+| multicast | [bool](#bool) |  |  |