feat: support link altnames/aliases

At the moment, we don't use/support aliases, but we might in the future.

Altnames are filled out by `systemd-udevd`.

This PR has two parts:

* show aliases & altnames in `LinkStatus`
* match links by aliases/altnames when we configure
  addresses/routes/links

This should make a transition to `systemd-udevd` less painful if the
previous link name is in `altNames`.

Forked rtnetlink for jsimonetti/rtnetlink#241

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

api/resource/definitions/network/network.proto

@@ -184,6 +184,8 @@ message LinkStatusSpec {
   BondMasterSpec bond_master = 28;
   WireguardSpec wireguard = 29;
   bytes permanent_addr = 30;
+  string alias = 31;
+  repeated string alt_names = 32;
 }
 
 // NfTablesAddressMatch describes the match on the IP address.

go.mod

@@ -104,7 +104,7 @@ require (
 	github.com/hetznercloud/hcloud-go/v2 v2.17.0
 	github.com/insomniacslk/dhcp v0.0.0-20240829085014-a3a4c1f04475
 	github.com/jeromer/syslogparser v1.1.0
-	github.com/jsimonetti/rtnetlink/v2 v2.0.2
+	github.com/jsimonetti/rtnetlink/v2 v2.0.3-0.20241216183107-2d6e9f8ad3f2
 	github.com/jxskiss/base62 v1.1.0
 	github.com/klauspost/compress v1.17.11
 	github.com/klauspost/cpuid/v2 v2.2.9

go.sum

@@ -414,8 +414,8 @@ github.com/jsimonetti/rtnetlink v0.0.0-20210525051524-4cc836578190/go.mod h1:NmK
 github.com/jsimonetti/rtnetlink v0.0.0-20211022192332-93da33804786/go.mod h1:v4hqbTdfQngbVSZJVWUhGE/lbTFf9jb+ygmNUDQMuOs=
 github.com/jsimonetti/rtnetlink v1.3.5 h1:hVlNQNRlLDGZz31gBPicsG7Q53rnlsz1l1Ix/9XlpVA=
 github.com/jsimonetti/rtnetlink v1.3.5/go.mod h1:0LFedyiTkebnd43tE4YAkWGIq9jQphow4CcwxaT2Y00=
-github.com/jsimonetti/rtnetlink/v2 v2.0.2 h1:ZKlbCujrIpp4/u3V2Ka0oxlf4BCkt6ojkvpy3nZoCBY=
-github.com/jsimonetti/rtnetlink/v2 v2.0.2/go.mod h1:7MoNYNbb3UaDHtF8udiJo/RH6VsTKP1pqKLUTVCvToE=
+github.com/jsimonetti/rtnetlink/v2 v2.0.3-0.20241216183107-2d6e9f8ad3f2 h1:4pspWog/mjnfv+B3rjEUfCoFL80T7J8ojK9ay8ApPCM=
+github.com/jsimonetti/rtnetlink/v2 v2.0.3-0.20241216183107-2d6e9f8ad3f2/go.mod h1:7MoNYNbb3UaDHtF8udiJo/RH6VsTKP1pqKLUTVCvToE=
 github.com/json-iterator/go v1.1.12 h1:PV8peI4a0ysnczrg+LtxykD8LfKY9ML6u2jnxaEnrnM=
 github.com/json-iterator/go v1.1.12/go.mod h1:e30LSqwooZae/UwlEbR2852Gd8hjQvJoHmT4TnhNGBo=
 github.com/jxskiss/base62 v1.1.0 h1:A5zbF8v8WXx2xixnAKD2w+abC+sIzYJX+nxmhA6HWFw=

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

@@ -11,12 +11,14 @@ import (
 	"net"
 	"net/netip"
 	"os"
+	"slices"
 
 	"github.com/cosi-project/runtime/pkg/controller"
 	"github.com/cosi-project/runtime/pkg/resource"
 	"github.com/cosi-project/runtime/pkg/safe"
 	"github.com/jsimonetti/rtnetlink/v2"
 	"github.com/mdlayher/arp"
+	"github.com/siderolabs/go-pointer"
 	"go.uber.org/zap"
 	"go4.org/netipx"
 	"golang.org/x/sys/unix"
@@ -117,12 +119,28 @@ func (ctrl *AddressSpecController) Run(ctx context.Context, r controller.Runtime
 }
 
 func resolveLinkName(links []rtnetlink.LinkMessage, linkName string) uint32 {
+	if linkName == "" {
+		return 0 // should never match
+	}
+
+	// first, lookup by name
 	for _, link := range links {
 		if link.Attributes.Name == linkName {
 			return link.Index
 		}
 	}
 
+	// then, lookup by alias/altname
+	for _, link := range links {
+		if pointer.SafeDeref(link.Attributes.Alias) == linkName {
+			return link.Index
+		}
+
+		if slices.Index(link.Attributes.AltNames, linkName) != -1 {
+			return link.Index
+		}
+	}
+
 	return 0
 }
 

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

@@ -238,6 +238,74 @@ func (suite *AddressSpecSuite) TestDummy() {
 	}
 }
 
+func (suite *AddressSpecSuite) TestDummyAlias() {
+	dummyInterface := suite.uniqueDummyInterface()
+	dummyAlias := suite.uniqueDummyInterface()
+
+	suite.T().Logf("dummyInterface: %s, dummyAlias: %s", dummyInterface, dummyAlias)
+
+	conn, err := rtnetlink.Dial(nil)
+	suite.Require().NoError(err)
+
+	defer conn.Close() //nolint:errcheck
+
+	dummy := network.NewAddressSpec(network.NamespaceName, "dummy/10.0.0.5/8")
+	*dummy.TypedSpec() = network.AddressSpecSpec{
+		Address:     netip.MustParsePrefix("10.0.0.5/8"),
+		LinkName:    dummyAlias, // use alias name instead of the actual interface name
+		Family:      nethelpers.FamilyInet4,
+		Scope:       nethelpers.ScopeGlobal,
+		ConfigLayer: network.ConfigDefault,
+		Flags:       nethelpers.AddressFlags(nethelpers.AddressPermanent),
+	}
+
+	// it's fine to create the address before the interface is actually created
+	for _, res := range []resource.Resource{dummy} {
+		suite.Require().NoError(suite.state.Create(suite.ctx, res), "%v", res.Spec())
+	}
+
+	// create dummy interface
+	suite.Require().NoError(
+		conn.Link.New(
+			&rtnetlink.LinkMessage{
+				Type: unix.ARPHRD_ETHER,
+				Attributes: &rtnetlink.LinkAttributes{
+					Name: dummyInterface,
+					MTU:  1400,
+					Info: &rtnetlink.LinkInfo{
+						Kind: "dummy",
+					},
+				},
+			},
+		),
+	)
+
+	iface, err := net.InterfaceByName(dummyInterface)
+	suite.Require().NoError(err)
+
+	// set alias name
+	suite.Require().NoError(
+		conn.Link.Set(
+			&rtnetlink.LinkMessage{
+				Index: uint32(iface.Index),
+				Attributes: &rtnetlink.LinkAttributes{
+					Alias: &dummyAlias,
+				},
+			},
+		),
+	)
+
+	defer conn.Link.Delete(uint32(iface.Index)) //nolint:errcheck
+
+	suite.Assert().NoError(
+		retry.Constant(3*time.Second, retry.WithUnits(100*time.Millisecond)).Retry(
+			func() error {
+				return suite.assertLinkAddress(dummyInterface, "10.0.0.5/8")
+			},
+		),
+	)
+}
+
 func (suite *AddressSpecSuite) TearDownTest() {
 	suite.T().Log("tear down")
 

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

@@ -183,27 +183,42 @@ func (ctrl *LinkConfigController) Run(ctx context.Context, r controller.Runtime,
 			return fmt.Errorf("error listing link statuses: %w", err)
 		}
 
+	outer:
 		for _, item := range list.Items {
 			linkStatus := item.(*network.LinkStatus) //nolint:forcetypeassert
 
-			if _, configured := configuredLinks[linkStatus.Metadata().ID()]; !configured {
-				if linkStatus.TypedSpec().Physical() {
-					var ids []string
+			if _, configured := configuredLinks[linkStatus.Metadata().ID()]; configured {
+				continue
+			}
 
-					ids, err = ctrl.apply(ctx, r, []network.LinkSpecSpec{
-						{
-							Name:        linkStatus.Metadata().ID(),
-							Up:          true,
-							ConfigLayer: network.ConfigDefault,
-						},
-					})
-					if err != nil {
-						return fmt.Errorf("error applying default link up: %w", err)
-					}
+			if linkStatus.TypedSpec().Alias != "" {
+				if _, configured := configuredLinks[linkStatus.TypedSpec().Alias]; configured {
+					continue
+				}
+			}
 
-					for _, id := range ids {
-						touchedIDs[id] = struct{}{}
-					}
+			for _, altName := range linkStatus.TypedSpec().AltNames {
+				if _, configured := configuredLinks[altName]; configured {
+					continue outer
+				}
+			}
+
+			if linkStatus.TypedSpec().Physical() {
+				var ids []string
+
+				ids, err = ctrl.apply(ctx, r, []network.LinkSpecSpec{
+					{
+						Name:        linkStatus.Metadata().ID(),
+						Up:          true,
+						ConfigLayer: network.ConfigDefault,
+					},
+				})
+				if err != nil {
+					return fmt.Errorf("error applying default link up: %w", err)
+				}
+
+				for _, id := range ids {
+					touchedIDs[id] = struct{}{}
 				}
 			}
 		}

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

@@ -410,11 +410,15 @@ func (suite *LinkConfigSuite) TestDefaultUp() {
 		),
 	)
 
-	for _, link := range []string{"eth0", "eth1", "eth2", "eth3", "eth4"} {
+	for _, link := range []string{"eth5", "eth1", "eth2", "eth3", "eth4"} {
 		linkStatus := network.NewLinkStatus(network.NamespaceName, link)
 		linkStatus.TypedSpec().Type = nethelpers.LinkEther
 		linkStatus.TypedSpec().LinkState = true
 
+		if link == "eth5" {
+			linkStatus.TypedSpec().AltNames = []string{"eth0"}
+		}
+
 		suite.Require().NoError(suite.state.Create(suite.ctx, linkStatus))
 	}
 

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

@@ -8,6 +8,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"slices"
 
 	"github.com/cosi-project/runtime/pkg/controller"
 	"github.com/cosi-project/runtime/pkg/resource"
@@ -159,13 +160,31 @@ func SortBonds(items *safe.List[*network.LinkSpec]) {
 	})
 }
 
-func findLink(links []rtnetlink.LinkMessage, name string) *rtnetlink.LinkMessage {
+func findLink(links []rtnetlink.LinkMessage, name string, allowAliases bool) *rtnetlink.LinkMessage {
+	if name == "" {
+		return nil // should never match
+	}
+
 	for i, link := range links {
 		if link.Attributes.Name == name {
 			return &links[i]
 		}
 	}
 
+	if !allowAliases {
+		return nil
+	}
+
+	for i, link := range links {
+		if pointer.SafeDeref(link.Attributes.Alias) == name {
+			return &links[i]
+		}
+
+		if slices.Index(link.Attributes.AltNames, name) != -1 {
+			return &links[i]
+		}
+	}
+
 	return nil
 }
 
@@ -202,7 +221,7 @@ func (ctrl *LinkSpecController) syncLink(ctx context.Context, r controller.Runti
 	case resource.PhaseTearingDown:
 		// TODO: should we bring link down if it's physical and the spec was torn down?
 		if link.TypedSpec().Logical {
-			existing := findLink(*links, link.TypedSpec().Name)
+			existing := findLink(*links, link.TypedSpec().Name, false) // logical links don't have aliases
 
 			if existing != nil {
 				if err := conn.Link.Delete(existing.Index); err != nil {
@@ -226,7 +245,7 @@ func (ctrl *LinkSpecController) syncLink(ctx context.Context, r controller.Runti
 			return fmt.Errorf("error removing finalizer: %w", err)
 		}
 	case resource.PhaseRunning:
-		existing := findLink(*links, link.TypedSpec().Name)
+		existing := findLink(*links, link.TypedSpec().Name, !link.TypedSpec().Logical) // allow aliases for physical links
 
 		var existingRawLinkData []byte
 
@@ -312,7 +331,7 @@ func (ctrl *LinkSpecController) syncLink(ctx context.Context, r controller.Runti
 
 			// VLAN settings should be set on interface creation (parent + VLAN settings)
 			if link.TypedSpec().ParentName != "" {
-				parent := findLink(*links, link.TypedSpec().ParentName)
+				parent := findLink(*links, link.TypedSpec().ParentName, true) // allow aliases for physical links/parents
 				if parent == nil {
 					// parent doesn't exist yet, skip it
 					return nil
@@ -353,7 +372,7 @@ func (ctrl *LinkSpecController) syncLink(ctx context.Context, r controller.Runti
 				return fmt.Errorf("error listing links: %w", err)
 			}
 
-			existing = findLink(*links, link.TypedSpec().Name)
+			existing = findLink(*links, link.TypedSpec().Name, false) // link is created by name
 			if existing == nil {
 				return fmt.Errorf("created link %q not found in the link list", link.TypedSpec().Name)
 			}
@@ -596,15 +615,15 @@ func (ctrl *LinkSpecController) syncLink(ctx context.Context, r controller.Runti
 
 		bondMasterName := link.TypedSpec().BondSlave.MasterName
 		if bondMasterName != "" {
-			if master := findLink(*links, bondMasterName); master != nil {
+			if master := findLink(*links, bondMasterName, false); master != nil { // bond master can't be an alias
 				masterName = bondMasterName
 				masterIndex = master.Index
 			}
 		}
 
 		bridgeMasterName := link.TypedSpec().BridgeSlave.MasterName
 		if bridgeMasterName != "" {
-			if master := findLink(*links, bridgeMasterName); master != nil {
+			if master := findLink(*links, bridgeMasterName, false); master != nil { // bridge master can't be an alias
 				masterName = bridgeMasterName
 				masterIndex = master.Index
 			}